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Credit: Brookhaven National Laboratory
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Interview of Sam Aronson by David Zierler on June 23, 2020
Niels Bohr Library & Archives, American Institute of Physics,
College Park, MD USA,
For multiple citations, "AIP" is the preferred abbreviation for the location.
In this interview, David Zierler, Oral Historian for AIP, interviews Samuel Aronson, Director Emeritus of Brookhaven National Laboratory. He discusses his more recent work as director of the RIKEN Institute and his involvement with the National Offshore Wind R&D Consortium. Aronson recounts his childhood on Long Island, and he describes the impact of Sputnik on him personally and on the country generally. He describes his undergraduate education at Columbia and the relationship he developed with Mel Schwartz, and he discusses Schwartz’s collaborations with Leon Lederman and Jack Steinberger. Aronson describes his decision to pursue his graduate degree at Princeton, and his interest in working at the Princeton-Pennsylvania Accelerator Center. He discusses his involvement in the study of the decay of neutral K mesons into a pion and an electron and a neutrino. Aronson recounts his work with Valentine Telegdi at the Fermi Institute, and he describes Telegdi’s research at the ZDS in Argonne in kaons. He discusses his faculty appointment at the University of Wisconsin and his research on neutral kaons, and he describes the fundamental and concurrent work going on at Brookhaven and SLAC. Aronson explains the origins of his collaboration with Ephraim Fischbach on the Fifth Force, and he describes his attraction in moving to Brookhaven where the ISABELLE proton-proton collider was in development. He describes the Relativistic Heavy Ion Collider and PHENIX program, and he explains his promotions and increasing responsibilities culminating in his being named director of Brookhaven. Aronson discusses the rise of cosmology from within the field of particle physics, and he describes the role of DOE in supporting basic science at the lab. At the end of the interview, Aronson shares his views on the future of particle physics and some major outstanding questions that will continue to animate the field.
Okay. This is David Zierler, oral historian for the American Institute of Physics. It is June 23, 2020. It is my great pleasure to be here with Dr. Samuel Aronson. Sam, thank you so much for being with me today.
You're welcome, David. Thanks for the offer.
Okay. All right, so to start, please tell me your title and institutional affiliation.
Well, I spent most of my career affiliated with Brookhaven National Laboratory, from which I’m retired and on some sort of emeritus status and representing the lab in only one external organization at the moment. So most of my work is focused elsewhere to the extent that I’m still trying to keep busy.
What kinds of things have you been involved with since you went emeritus?
Well, for a while I continued at the lab as the director not of the laboratory, but after that, the director of the RIKEN Institute. I don't know if you're familiar with that.
Yeah, mm-hmm [yes].
Okay. I succeeded Nick Samios, who was also a lab director, and also a director of the RIKEN Institute, and did that for maybe three years. So although I retired in 2015, I was still doing that job into 2016 and then informally stopped working at the lab as well as being retired.
Now before the pandemic, would you still go in?
Only very occasionally. The work that I was doing even before the pandemic for the lab had to do with an external organization called the National Offshore Wind R&D Consortium, which is a partner effort between Brookhaven and Stony Brook University. It has DOE funding as well as NYSERDA funding from the State of New York. So I serve on the board. Before the pandemic we met for board meetings and other large meetings in Manhattan, but since then it’s been all phone. We canceled several in-person meetings, and most of the rest is usually by phone anyway.
Right, right. So that aspect hasn’t changed too much for you.
No, not much at all.
All right. So Sam, let’s take it right now back to the beginning. Let’s start with your parents. Where are your parents from?
My parents were born where I was born, in Huntington, New York here on Long Island.
What were your parents’ professions?
My father was a partner together with his brother and brother-in-law in a furniture business that had grown out of a business that my grandfather started, selling farming equipment and seeds and fertilizer and so on and that sort of turned into a general store. Then they had washing machines and other appliances and eventually carpets and furniture, and by the time I came along, it was a furniture store.
Was your mom involved in the business also?
No. My mother was a homemaker most of her life. Earlier in life she played the piano in local bands, gave piano lessons. After my father passed away, she volunteered at local schools.
Socioeconomically, was your family-- Would you consider your upbringing pretty middle class?
Yes, I would.
Did you go to public schools throughout childhood?
Yeah. The town of Huntington has two school districts, and I went to one of those based on where we lived.
Mm-hmm [yes], mm-hmm [yes]. When did you start to exhibit interest in math and science? Early on?
Yeah, I would say so. Not so clearly focused in the direction I wound up going, but it always attracted me, especially scientific work, experimental scientific work.
Were you interested in physics specifically growing up?
You know, I would say not, but maybe what the turning point for that was in 1957 I was in the tenth grade and Sputnik went up.
Then everybody’s hair was on fire and new courses in physics and mathematics were introduced at the high school level. I was halfway through high school biology in the tenth grade, and suddenly I was in advanced science classes. In fact, that was the end of my biology education, but the start of my real focus on physics. I hung out with a bunch of guys who were nerds like me also and we were all in that class, so it seemed to… Just going along with the flow there seemed to make sense.
So Sputnik really had that immediate impact even on your own education in high school.
Absolutely. I mean, the country took it seriously. They were already behind in the space race. What were they going to do?
Right, right. Do you remember? What was the challenge of Sputnik in terms of how the United States responded from your vantage point as a tenth grader?
It was all about getting into space from my vantage point. There were military and political consequences and concerns, But actually orbiting the Earth was a step ahead and I think the US wanted its edge back. So they marshaled all the students who had a proclivity for that and started to educate them in a completely different way in very short time.
Did you have good physics teachers in high school?
No. My physics class, the teacher was also the football coach.
The best teacher I had in high school was actually my math teacher, who was suddenly teaching us calculus. He actually didn't know calculus very well, but he was his own man and decided that after class or during lunch or something, we would get together with him and together we’d figure out calculus. So he let himself let us into kind of a curiosity-based study of calculus. I never forgot that. I never forgot that the barrier between teachers and students is artificial even in high school, but people who were comfortable in their own skin on that side of the curtain could open it easily.
That’s a real act of humility also on the part of a teacher.
When you were thinking about college programs, were you thinking specifically about physics, or you majored later on?
Later on. Well, no. I would say by the time I got to college—and I’m not sure how this happened—I knew that I wanted to major in physics. Even a physics major where I went to college didn't start taking any physics classes until the second semester or maybe the beginning of sophomore year. I don't remember now. But I had plenty of time to… Oh, there’s one thing I should say.
When I was applying to schools, most of my friends applied—this was their wish school—to MIT. My father had the wisdom to tell me not to do that. He had been educated in a liberal arts college in upstate New York up until the Depression forced him to come home and work in the family business, and he thought I was never going to get that kind of grounding in the classics and the broader view of Western thought and so on. So he encouraged me to go to a liberal arts school.
Interesting. Knowing that you wanted to pursue science, he still thought the liberal arts--
Yeah, for sure.
He knew where I was headed, but he wanted me to get a general education first. So I wound up going to Columbia College in New York City where they had at that time (and still have) a core curriculum, which there’s a massive amount of reading of philosophy and history and Western civilization, and other courses as well. I found out I was a pretty good writer taking English there. I found out that I was actually pretty good at solving physics problems just by helping other kids figure them out. That sort of came naturally to me. I’m talking about mechanics, statics, so nothing too deep, but I understood how the math went with the problems and that was the key to solving the problems. In fact, today I’m tutoring a high school student who is struggling with statistics and probability. He wants to go into a business course when he goes to college, but I can still help him decode word problems and how to deal with them. So that’s something that I always had.
Your father’s advice served you well, it sounds.
It did. It certainly did. I think my life is much richer, intellectually richer for sure, for having that background. So yeah, I owe—that to my father.
So you only declared physics, what, as a sophomore, a junior?
I was a physics major coming out of my freshman year, so as a sophomore, yes.
Who were some of the professors in the department that you became close with as an undergraduate?
The one that I became closest to and with whom I had at least part of my scientific career working together with later on in life was Mel Schwartz, a Nobel Prize winner. He was a very down-to-earth, very smart guy. I enjoyed working with him. When I connected with him later, I was an assistant professor at the University of Wisconsin. He came to give a talk on an experiment that he had done at Brookhaven National Laboratory, which I had not interacted with before except maybe a class trip in high school. That experiment sounded fascinating to me. I was at that time working on experiments at Fermilab, also in particle beams as this experiment was, and I could see a way to do this experiment better at Fermilab. So I talked to him afterwards and we wound up doing a couple of experiments at Fermilab. As a guy coming up for tenure at the University, that was not a smart move. I should have worked with tenured professors on whatever they were doing, but I didn't have the sense of career at that point, maybe never have. But in that case, I followed the physics that interested me rather than signing up as a soldier in somebody else’s experiment.
What were Mel’s research projects during your undergraduate years? What was he working on at that time?
Well, in my undergraduate years he was working with Leon Lederman and Jack Steinberger, who were also on the faculty there, and others on a muon-neutrino experiment at Brookhaven. Actually, I should say a neutrino experiment because they got the Nobel Prize for discovering that there was more than one kind of neutrino. The one associated with the electrons and found in beta decay, and the one that was associated with muon interactions and muon decay was different. That experiment was a big early step toward what we call The Standard Model. At that time, quarks were new. I was trying to understand the current level, which is essentially still the current level of understanding about subatomic, subnuclear physics and was not working on an experiment as an undergraduate. In fact, my undergraduate lab work was as a research assistant in a solid state lab. That’s where there was a job.
Oh! Who ran that lab?
A young faculty member named Sven Hartmann. I was working in his lab in the fall of 1963 and one of Hartmann’s grad students (a Brazilian guy named Rama Gazzinelli) burst into the Lab and said Kennedy’s been killed. The next thing I remember is having left the lab and was walking around the Columbia campus in a daze, like everyone else, talking about nothing else. I interacted with Sven Hartmann, many years later when I was working with another Columbia grad who was then a physics professor at Purdue. Sven was a tenured professor and Physics Department Chairman at Purdue at that time. I’ll get back to that day at Purdue later…
Did you have any summer internships at Brookhaven or any of the other national labs?
No, I didn't. I worked back here on Long Island one, maybe two summers, as a surveyor’s assistant, which had not much to do with it except I wound up surveying long beam lines later on, so maybe it helped. But I didn't really have a physics position anywhere. The closest thing I had to it was toward the end of my college career, I worked for a small company on Long Island called TRG. It was a research and development private for-profit company. They had a Navy contract to find methods to acoustically quiet down the Navy ships that needed sonar to do their work because that pounding, that vibration of the part of the hull under the water actually was noise for sonar. So they had a solution to try. I worked on that first in their lab one summer in a little setup in their lab that simulated a little piece of the bottom of a ship. It had a vibrating thing on it and an accelerometer, and we tried various mechanical attachments to this that would resonate at the frequency that the sonar used. We were trying to get cancellation of the ship’s vibration at that frequency.
The second summer we worked on a destroyer out of Newport, Rhode Island for about ten days actually testing this because it seemed to work in the lab. So I spent… That was a lot of fun, actually. It had nothing to do with physics per se except the very basic mechanics of physics. But it was a pleasure being out past the 1000-fathom curve in the Atlantic Ocean steaming around in circles and playing with this equipment. It was not so different from physics experiments I did for most of the rest of my career in terms of instrumentation, staying up all night on shifts, all kinds of stuff. Plus I got to tell the captain when to stop and start the ship and what direction, what speed to go at because I needed that data. So that was a lot of fun as a kid.
Was there a senior thesis at Columbia?
So I’m curious, Sam. As you were thinking about graduate school, how well did you identify yourself either in terms of wanting to pursue theory or experimentation as a graduate student?
I knew from informal… let me call them seminars that were conducted by some theorists at Columbia at the time on the quark model. I knew from that that… And I’m not sure I can explain why, but I knew from that that my path was not in the direction of theoretical physics. It was experimental. I think my favorite course as an undergraduate physics student was actually a physics lab course where I somehow fell very naturally into that to the point where the person teaching the lab part of that course asked me to try out on my own some new equipment that he was thinking about for demonstrating other physics properties. So I did some off-the-clock, if you want to call it that, little experiments and figured out the outcome just from what I knew about mechanics, and those became a lab assignments for future generations. So that’s what turned me on and so that’s the direction I took.
I did very well academically in physics in college. When it was time to start thinking about grad school, Mel Schwartz, who had taken over as undergraduate advisor from Allan Sachs, encouraged me to stay at Columbia, so I knew I was doing something right. But in fact, I wanted to go to Princeton. Why? Because Princeton and the University of Pennsylvania had a small accelerator, a proton synchrotron with a 3 GeV beam energy that seemed more than anything at Columbia that I could do experiments with in particle physics, which got me turned on from learning about the quark model. So I thought being able to access a functioning synchrotron at a high enough energy to do significant experiments was a good idea.
Mm-hmm [yes]. Sam, did you ever consider Stanford and all the excitement that was happening with the development of SLAC during that time?
No, I didn’t consider that. I was not focused on the wider world. I was still just following my nose, but it was stuff that I thought I’d like to do. I did do some interesting experiments at the synchrotron that was called PPA, the Princeton-Pennsylvania Accelerator Center, and from those experiments I got invited by someone at the University of Chicago to be a post-doc in his group. So it sort of clicked, but without me actually planning anything about my career or taking a broader look, which I could regret nowadays if I wanted to, but in fact, I don't think I was equipped to take that kind of synoptic view of my career and decide what to do as a graduate student. So I just did what I thought was interesting.
Was there a particular professor that you also wanted to work with at Princeton, or it was really the synchrotron that attracted you?
I wanted to work with Val Fitch or Jim Cronin, and that didn't work out. I wound up working for a couple of assistant professors in physics, one of whom moved on from Princeton and the other of whom, who was my thesis advisor, kind of lost interest in the experiment I was doing. Jim Cronin was interested in it, and I’ll tell you a story about where that went later. But I wound up basically building the key piece of equipment and doing all the analysis sort of unsupervised. I think that’s what got me the post-doc at University of Chicago. I sort of knew what to do, self-taught in terms of being a post-doc.
What was the piece of equipment that you built?
Actually, there were two. One was a Marx generator, a device that would generate very short half-million volt pulses. In those days, there were already spark chambers being used for particle physics, electronic devices to detect where the tracks from collisions or decays were. We had the idea—or it wasn’t my idea, but there was an idea around to build a…instead of a lot of thin gaps for a stack of spark chamber gaps to follow the trajectory of particles, to build one single very wide gap with a very high voltage that would be able to see the tracks in one gap. I’m not sure what was so important about that, and it didn't become a popular alternative to thin gap spark chambers. I don't know how many—probably not many other wide-gap spark chamber experiments were built and used, but I got a good piece of physics out of it, and I got to learn how to run a lathe because the summer before grad school started at Princeton, I spent it there, often in the machine shop at the PPA learning how to do stuff from a machinist there. That all came in handy for building that piece of equipment. I built a prototype; it worked. I built another one that was high enough performance to work in this experiment. I also took the lead in building this wide-gap spark chamber. So that led to an experiment… Tell me if I’m going off the track here.
No, this is great. No, this is great.
That led to an experiment where we studied the decay of neutral K mesons into a pion and an electron and a neutrino, Ke3 decay it’s called. The reason it was interesting was that a student who was ahead of me had done this experiment with charged kaons decaying in the same mode and got a result for the form factor for the decay. We can go into discussing that later, I think. So some important parameter that told you something about the interactions that were involved basically measured on a scatter plot the density of that scatter plot of multiple independent events, and he got a value for this parameter. Meanwhile, out in Chicago at Argonne National Laboratory—somebody else did an experiment with neutral kaons and got a different answer. That was surprising and…
How did you find out about this?
I actually found out about this during the experiment, I think from Jim Cronin, who organized a very small get-together involving me and the student who was ahead of me. Separately, we had done both charged and neutral Ke3 decay and got basically the same answer within statistical errors for this form factor, whereas the guy—maybe I shouldn't mention his name—out in Chicago got a statistically very different result for neutral Ke3 decay.
The reason I don't want to mention his name is he gave me one of the biggest scares of my life at that time by coming to this meeting and throwing his graduate student under the bus, basically giving up defending his result and saying it was his student’s fault. I’m a student at that time. I’m a grad student and it never occurred to me that that’s how people would behave. It’s a very competitive field. But the groups were small. It was really you knew everybody and what they could do, what they couldn't do, and the same in all the other groups that you were competing with. So that was a rude awakening about the politics of physics for me.
So, in the end, the result that I got, which agreed with the locally obtained result by the other student, that was the answer, but the statistics weren't great and it’s been measured much better since then. I never worked there again, by the way. PPA closed down in 197, a few years after I left grad school. Like everyone else in the particle physics community, my focus was on bigger accelerators, and the positions I took in Chicago at the Fermi Institute there as a post-doc and then in Wisconsin in Madison as an assistant professor—all the work I was interested in was at the ZGS at Argonne National Laboratory and Fermilab. We did some good experiments at both of those, but the only thing… I’m coming back to Stanford for one second.
One of my group leader’s former students was Dave Fryberger, a physicist at SLAC and he sometimes came back and worked on these experiments because he had an attachment to that group. When it came time to analyze the data for experiments that we were doing at Argonne—and by the time there was Fermilab, it was not this way, but certainly from Argonne—we didn't have enough computing power available to us at either Argonne or at University of Chicago to analyze the stuff that we were doing. But at Stanford was a very big (for those days) IBM 360 that could analyze the data, so I became the digital link between Chicago and Stanford because I would schlep out there with boxes of data tapes and analyze them.
People are still going to wherever the widest bandwidth and the fastest computers are, so that’s what we were doing, chasing the hardware.
Sam, I want to step back just a second. I’m curious how you developed your dissertation topic. How did that come about?
The two assistant professors I worked for as a grad student knew wanted to do a K0e3 experiment to see if they could understand why the result from the previous experiment at Argonne was not consistent with the other one (with charged K mesons) that had been done at Princeton. So I didn't come up with the idea to do that experiment. I worked for them and we started down that path. I just finished it; I didn't start it.
What were some of the major research questions that not only you in your specific research, but more broadly in your field—what were some of the major research questions that were going on during that time?
One of them was very close to what I was working on because it involved neutral K mesons, which are very interesting beasts. They come in two different types, particle and anti-particle, but they mix quantum mechanically to produce two observable K0s that have different decay modes and very different lifetimes, one very long and one very short. It was very important to understand and exploit that quantum property. For example, you could do experiments to measure the mass difference between these two different particles using the oscillations… the interference effectively between the long- and short-lived neutral K mesons as they decayed. You could study interactions of neutral K mesons with nuclei by doing regeneration experiments, which means you take a beam of long-lived K mesons that travel a long way. At Fermilab, I think our beam line was a couple of hundred meters long. So all the short-lived kaons are decayed away, but when you run the long-lived kaons through material – because of different interaction probabilities of the particle and its anti-particle – you get a different mix of long-lived and short-lived ones, regenerating some of the short-lived ones coming out of that piece of material. Then you can observe the decay of the long- and short-lived K0 and the oscillatory behavior of the decay rate with distance.
There’s a very small difference in the masses, so you get very long oscillation waves in this quantum interference between the two different decay times. It was a wonderful kind of microscope to look at particles which are close in mass and have at least some decay modes in common.
Well, I have to go back to Fitch and Cronin for a moment. They won the Nobel Prize for discovering the violation of CP symmetry because some of the long-lived K mesons, which are not supposed to decay into two pions, do so because of this mixing. So that mixing is only possible if this principle is broken in weak decay of particles. But you asked me a wider ranging question…
It was the general question about the broader research questions that you specifically in the field were thinking of in that time period.
The other one that I meant to mention was the experimental exploration of the quark model, leading to the discovery of heavier mesons and baryons than the proton and the neutron. The quark model allowed for different families of quarks and leptons, the different mass scales that led to particles like the neutron and proton, but unstable, heavier, and with particular predictable decay moments. Much of this work was done with bubble chambers at the highest accelerator beam energy available.
How did Professor Chen get to be your advisor? How did that play out?
Not so well. I was disappointed to be left what I thought was holding the bag on this experiment because it was a lot of work and I spent a lot of time taking 24-hour shifts in that experiment, or finding colleagues at the synchrotron who would mind it while I went and, you know, got something to eat or whatever. He also didn't participate in the data analysis and interpretation and was working on other experiments by that time. He moved on to Michigan State University from Princeton and later moved on MSU as well. He was a strange guy and didn't work particularly well with others. One thing, though, thinking of Chen brought to mind Herb Chen, one of my fellow students at Princeton. Herb went on to become a very productive and well-known neutrino physicist.
Oh, okay. Yeah.
Herb was a bit ahead of me. He introduced me to Monte Carlo programs used to simulate experimental outcomes and design experimental set-ups to maximize performance for particular interactions and decays. He died quite young, tragically, of leukemia. I thought he was the smartest…both the brightest and the most driven physicist in my graduate school class at Princeton, and I expected great things of him—and he did do great things, but cut short.
Where did he go on after Princeton?
We stayed in touch. We were friends during graduate school. I took him sailing once or twice, and I think probably his presence there in the class made it—and others that I was friendly with in that small class of maybe 20, 25 grad students in physics. There was a lot of camaraderie. A number of us were working at PPA.
[Chuckles] Sam, how did the opportunity at the Fermi Institute come about for you?
That was in the person of Valentine Telegdi.
Oh, yeah. Yeah.
You know that name?
He was a professor at the Enrico Fermi Institute at the University of Chicago and was doing experiments both in neutral kaon physics and in muonium, measuring properties of muonium using a cyclotron in the basement of the Fermi Institute in Chicago. So given my background, I took the path towards Argonne and kaon decays, but a number of grad students or post-docs in that group worked on both. I didn't. Most of the post-docs were former students of Telegdi’s and he was a bit of a tyrant. Some of them were afraid of him, but he seemed to treat me with a little bit more… with a nicer demeanor because I was from out of town.
I believe he hired me or offered me a job because he came to Princeton to give a colloquium. He probably learned—and I never bothered to follow this up and figure this out. He probably learned from Jim Cronin about the experiment I was working on and why I was doing it and had done it pretty much on my own, because one of the things he said to me when I first met him, which was at Princeton, that he understood that I basically finished it single-handed. I said yes and he said, “Well, I have a small group and I’m trying to do two different things at once. That sounds like you would fit in there,” and I did.
This was a pretty exciting time to be at the Fermi Institute.
Yes. Nambu was the big theorist there at the time.
Right, right. Was the phrase string theory bandied about in those early years, or this comes later on?
Later. Later, at least for me.
I mean it evolved out of quantum field theory and other ingredients, but I never heard the term string theory till much later.
Mm-hmm [yes], mm-hmm [yes]. Your appointment at the Fermi Institute—was the idea that you would pursue your own research, or were you going to be slotted into an existing research project?
I joined that group because of Telegdi’s ongoing program at the ZGS in Argonne in kaons because I was still interested in pursuing that, especially the experiments that were then possible when one understood this interplay between K0s and anti-K0s and how that manifested itself through the quantum interference. So I really wanted to work on that. At that time… This comes a little bit later. We were working on regeneration experiments. At the beginning of that, he had done some K0 experiments at the ZGS. I think this thing really reached maturity when we were able to go to Fermilab with much higher energy beams and much more copious production of K0 mesons. But he was already interested in the same thing as an experimentalist but with a decidedly more theoretical bent than his students and post-docs, including me. But that was exactly what I wanted to be working on, so I didn't create a new line of research till I got to the faculty at Wisconsin.
It sounds like there was no need for you to. You couldn't have come up with a better research group if you started it from scratch.
Well, that’s certainly true, but that was dumb luck. I mean what brought me and Val together was completely above my pay grade, but it turned out we were simpatico and interested in the same topics on the kaons. I was not interested in cyclotron work on muonium, which was much more advanced, advanced enough for Telegdi to have gotten himself into several muonium battles with Vernon Hughes at Yale, among others. Telegdi got into a lot of battles and he generally held his own.
Who was on the opposing side? What kind of battles are you talking about?
The publication of Madame Wu’s discovery of parity violation. Telegdi and collaborators were on the same trail and delivered a paper with a similar result to Phys Rev Letters on the same time scale. He suspected that Columbia rigged this so that they published Madame Wu’s paper and not his, so he got into a battle with… I don't know if he got into a battle with T. D. Lee on this parity violation experiment, but he certainly did with Leon Lederman. There was a note on Val’s corkboard over his desk from Leon about “burying the hatchet.” I don't remember the exact words, but that was a prized possession. [Laughter] Anyway.
So muonium I was not interested in, and working at the ZGS was not the easiest way to do that (K0) work. It might have been easier to do it at the AGS in Brookhaven, but we didn't do it. Brookhaven’s AGS synchrotron was famous for the stuff that Fitch and Cronin did and Schwartz, Lederman and Steinberger on neutrinos and so on, but it was certainly a higher energy and higher flux machine than the ZGS.
Sam, what was the research culture like at the Fermi Institute? Was it collaborative? Would people hang out at the cafeteria? Would they share their research with each other?
To me it seemed like that spirit lived within groups, which were rather separate. That’s how I saw it. All the people I consulted with were affiliated either with Val personally or in Val’s group or formerly in Val’s group, and I think it was the same with other research groups there as well. There were some internal rivalries on use of the cyclotron, on results, and so on. It was kind of a competitive place internally, I thought. I’m not sure that’s a bad thing because eventually you're going to… If nothing else, it’s good training in physics combat because you wind up doing that eventually when breakthroughs like parity violation come along and you…
Right, right. Did you feel any institutional connection to the physics program, the University of Chicago Department of Physics? Was there any kind of collaboration, or did it feel like a totally separate world?
It felt totally separate to me as a post-doc.
So there weren't professors that had dual appointments? It wasn’t like that?
Yes. Yes, there were, but there seemed to be quite a split between… The Fermi Institute was its own thing, even though it was populated with people like Telegdi and Cronin and others who had faculty appointments but also were research group leaders at the Institute.
Was this a particularly productive time for you in terms of publishing and presenting at conferences? Was that a big component of your time at the Fermi Institute?
It was a component. I gave some lectures on results that we arrived at—well, both at the ZGS and at Fermilab on K0 decays. I was very active in the analysis of that data in those days and very interested in the results, which led me into a really strange space later… I mean decades later. We’ll talk about that later. But I would say… I gave lectures at the APS meetings. I gave some colloquia at other universities, not a lot, but… I’d have to look at the full-blown version of my CV to see how many I did give. I was never very good about keeping track of that, but I would guess that during my four years I gave on the order of 10 or 12 lectures. One of the experiments… Well, the experiments that we were doing at both that I spoke mostly about were these regeneration experiments with neutral kaons, and those are long, hard experiments. I worked with some great people there, and the rate of publication was not the kind of factory-style publication organization that you see in experiments that have 500 or 2,000 physicists working on them nowadays. But in those days, there wasn’t the same division of labor, so I would say that in general there were less opportunities for giving talks. That’s how I saw it.
In terms of… Did you have a set limit on your time at the Fermi Institute, or you were sort of looking for your next opportunity and then left when that came available?
Yes, the latter. I was looking for an academic position. It was hard to make the transition to an academic position at the University of Chicago from the Fermi Institute, although some people did. I stayed four years as a post-doc and senior post-doc in Chicago and then moved to Madison where there was an assistant professor position in the particle physics group open. That’s where I met Lee Pondrom, whose name came up in the first line of your message.
Yes, yes. Sam, I’m curious. At this point, was that sort of an unexpected turn for you in terms of your trajectory and interest after Fermi Institute? Did you kind of think that you would end up like at a Brookhaven or a Fermilab or an Argonne kind of place?
Or were you specifically looking for a faculty appointment?
I was. I felt comfortable teaching. I thought that was important, actually, to the research part of my career.
And at Fermi Institute there was no teaching, I assume.
No, there wasn’t. It was at the university.
And except for internal seminars, there was nothing that looked academic there. Of course, some of those seminar leaders were people like Enrico Fermi, so not a bad place to be. [Chuckles] Lee must have told you that story about him as a grad student at University of Chicago watching Fermi give lectures off the cuff and thinking, “Well, when I grow up, I’ll be like that, too!” [Laughs] I love that story.
That’s great. The early ’70s was a pretty tough time in the job market for faculty positions.
Yeah. So wandering ahead and not thinking much about career opportunities, I went to what I felt was a very good group with a very diverse portfolio on physics research and experimental physics. Dave Cline was there and Dick Prepost, who worked at SLAC a lot, was there and Lee, others. I thought it was a great group.
What I didn't realize and didn't get much mentoring on in those days was that I had joined a department that was 50-strong in terms of physics faculty, 48 of whom were tenured, and there were two of us assistant professors, the other being Clint Sprott. Times being tough, it finally became clear that only one of us was going to get that job. I didn't get it; Clint did. He was sort of the heir apparent to the research in another area—not elementary particle physics, but in…more like the precursors to fusion containment, that kind of plasma physics. There was a grand old man in that field, Don Kerst, who I didn't interact with much, but it was clear that Clint was the future of that field at Wisconsin at that time. The particle physics group was so strong that it didn't need a successor. It had lots of them and lots of good faculty. Don Reeder was there. Ugo Camerini. It was, I think, asymmetric in terms of opportunity because of the needs of the department. The particle physics group made a valiant effort on my behalf, but it didn't work out. So I had to leave and find another job.
Did you take on graduate students when you were at Wisconsin?
Yes. I had three. I was interested in new kinds of detector technology to apply to physics, so we built some prototype chambers called drift chambers. That was a hot new topic in instrumentation in those days. They participated with me in some experiments that I worked on. One of them, Greg Bock, worked on the regeneration experiments and wound up with a big position at Fermilab eventually. Of the three students I had, he was the one who was drawn to the stuff that I was still doing as a professor at Wisconsin together with the Telegdi group and other collaborators on bigger and better regeneration experiments at Fermilab. Greg turned out to be very good. Another one, Dave Hedin, worked on the pi-mu atom experiment and wrote his thesis on the result. He moved on to a faculty position at Northern Illinois University and continues to do research at Fermilab. Bock worked with me on the regeneration experiments analysis as well, and that brings me a little closer to this strange turn that kaon physics took in my career later. But I don't want to get off the track you were on.
Yeah, we’ll return to that, but just to stay with the narrative, first I’m curious. How closely were you following the big… you know, the research that was coming out of SLAC in 1974, 1975? Was that relevant for your work?
I think it was relevant to everybody in particle physics because of the simultaneous discovery at Brookhaven and SLAC of charm particles carrying the charm quantum number. The person who was leading the effort at Brookhaven, Sam Ting, and Burt Richter at SLAC.
Richter would go on to win the Nobel Prize for this.
Yeah, that’s right, as did Sam Ting.
There was a lot of combat there. They’re both very combative people, and…
And Sam is often considered more of an outsider for a lot of reasons. You know, he has some controversial ideas.
Oh, yes. I understand what you're saying. Yes, that’s right. Back in these days, I think he was just a hard-driving particle experimentalist primarily. I have a Sam Ting story, if I can make a small diversion.
In 1973, I think, I went to Erice for a summer conference. Erice was a long-lasting, maybe still lasting site in Sicily for meetings run by Nino Zichichi in all kinds of fields, particle physics being the initial one. So I went there for that, and one of the speakers at that time was Sam Ting. He gave a talk on his work. I went up to him during the break and asked him a question which I can't remember now—some detail that I didn't understand about getting from step A to step B. So I snagged him at coffee and said, “What about this?” He said, “Well, that’s an extremely interesting question. Why don't you save it for the question and answer period when I finish?” So I did and I asked my question which he told me was very interesting. When he answered it in public, he said, “No, that’s a trivial detail. It doesn't actually matter.” He needed somebody to throw him a softball, I guess, or thought he might. He was actually wonderful as a lecturer, if you could keep up with him. He usually showed up at lectures with maybe a hundred slides — This is back in the days of all the slides were on foils, handwritten foils.
He would come with a stack like this and he’d include them all in a talk. We had no idea where he was after slide 75, but he just kept chugging along. Quite a guy. Anyway, he came back into my life later when I was at Brookhaven a little bit, but that’s also another story. So that’s the end of that diversion on Erice and my first encounter with Sam Ting. So again, I’m taking you off the narrative.
So on the narrative, what do you see… What was your most impactful research while you were at Wisconsin?
It turned out to be a follow-on to our work on K0 regeneration but its impact came when I was already at Brookhaven, and that’s where neutral kaons meet proposed new forces of physics.
So we can move on to Brookhaven, then.
Well, I can tell you what I worked on together at Fermilab while I was still at Wisconsin was on the experiments I did with Mel Schwartz after that colloquium he gave at Wisconsin. I knew that I was working in a beam line at Fermilab which would be the perfect place to do that experiment that he tried and couldn't quite do at Brookhaven and talked about at a higher energy where it would be easier and with more particles.
Mel was looking at a particular corner of… I don't know how to… Ah, yes, how to put that. He was looking at kaon decays into pions and muons and neutrinos, pi-mu decay it was called. He was looking at the events in which the pion and the muon came out with a very, very low relative velocity in the same direction. Some of the K decays emitted the pion and muon bound together. So-called pi-mu atoms. Why is this interesting? Because if there were an interaction between pions and muons, muons only feel the electromagnetic and weak interactions, not the strong nuclear interaction and we can forget about gravity. But if there were some hint of strong interactions in the muon or some other new physics, that would have had some effect on the rate at which pi-mu atoms are produced in that experiment in this one corner of phase space where they come out together and they form a small unstable pi-mu atom. And the question is how many of those are produced per billion K meson decays.
There’s a calculation for that that tells you what the rate is supposed to be. That was done by a theorist named Robin Staffin. He got an answer based on conventional physics that is dominated by the electrical attraction between the pion and the muon and got an answer. A discrepancy between that calculation and the measured rate of pi-mu production would tell you something else is going on.
Mel was doing an experiment at Brookhaven to measure the rate and couldn't find enough pi-mu atoms to see if there was a discrepancy. They got a result that was consistent with very large errors with Staffin’s calculation.
So my big idea was, well, we can do it with more energy and more statistics. I designed a system of magnets, simple magnets but with an unusual orientation among them. In between two of them was a conversion plate, a very thin piece of material that would dissociate any pi-mu atoms that came by, and then with them separated, you can measure their momentum and direction in detectors, which we already had in the experiment there. You could identify them cleanly with little background and more statistics and find out what the production rate of those things actually was.
I worked on that experiment with students and also with Bruce Winstein, who was a fellow post-doc in Telegdi’s group at the Fermi Institute and wound up making that jump to the faculty. Very bright guy, also now gone due to cancer. But he had a long and influential career at the University and at Fermilab.
We acquired and set up those magnets and the converter. We ran the experiment and actually were able to identify 300 pi-mu atoms, which was a massive increase in statistics over what Mel had gotten at Brookhaven and with very low background. We got the answer that comes out of the calculation based on conventional physics. In other words, there was no new physics.
The next thing I’m going to tell you about is also something that turned out not to be interesting from the point of view of possible new physics, but also had a lot of impact. I thought doing that experiment was the best thing that I did while I was at Wisconsin. I suggested to Mel that we do it. I designed what had to be added to the apparatus, and it worked. It was a lot of fun. So Mel and I worked together for a couple of years on that while I was still at Wisconsin, and then eventually also at Brookhaven.
So after that’s over, we move to… We’re going to go to Brookhaven by way of Purdue because I had a friend at Purdue, Ephraim Fischbach. Does that name ring a bell?
He was a year ahead of me at Columbia, physics theorist.
Did you work with him at Columbia?
No. We never worked together until I was at Brookhaven. But it had echoes of this regeneration stuff we did at Fermilab in it. The reason we’re going to take a detour through Purdue is because there I got back together with Ephraim, who invited me to come and knew I was looking for a job and he wanted to get me on the faculty there. That was such a riven faculty that professors were pulling me into their offices to tell me in private how bad so-and-so was in the department.
It happened to me more than once in a single day and I said, “Well, this sounds like the Hatfields and the McCoys. What would I want to do this for after having just been screwed out of a permanent position at Wisconsin?” I had a brief exit interview with the physics chair, Sven Hartmann and told him about the sociology of the particle physics groups. I was also applying to Brookhaven because my family… I mean my personal family in Chicago. I had married and we had two children by that time. We were leaving Madison for wherever, and we had lived near her parents for all that time, all that decade I spent in Chicago.
Your wife is from Chicago?
No, she was from Milwaukee. She passed away ten years ago. Her folks lived in Milwaukee, and we went to visit them either from Chicago or from Madison during the time that my two kids were born. So coming back to Long Island seemed like it would be a thing to do if there was a good job here at Brookhaven. By then I understood—or maybe I was just turned off to academia because of the situation in Wisconsin that I stepped into. But at that point I saw my future at a lab, not at an academic institution. I spent a lot of time while we were in Madison basically back and forth every week to Fermilab.
That was hard on my family, and I didn't want to do that again, I wanted to be living close to whatever I was doing. I wanted to be at a lab and being able to see my folks more regularly also was appealing. They certainly wanted to see their grandkids.
Sam, I’m curious. In going back and forth from Fermilab, at some point, I mean even if that opportunity had worked out for you at Wisconsin, maybe you would have considered, you know, in terms of your research, in terms of work-life balance that sort of being full-time at a national lab was more appropriate for you anyway.
I probably would have come to that conclusion. In fact, before I left Wisconsin, I was offered another job at the University of Wisconsin out at their synchrotron light source in Stoughton, just south of Madison, to run that facility, or to train for running that facility. I had no interest in that. I still wanted to do physics. I wasn’t interested in that kind of physics. But if I had stayed at Wisconsin in an academic position, I probably would eventually have wanted to go to a national lab near there or someplace. I don't think in the end… Looking back on it, I don't think teaching attracted me as much as research did.
Mm-hmm [yes], mm-hmm [yes]. Was there something about Brookhaven specifically in terms of the research that was going on there and what you were working on that made it a natural fit, beyond just the location?
What Brookhaven was doing… Well, I got offers from pretty much every experimental physics group to join whatever it is they were doing at the time, but what they hired me to do was to work on the development of a new proton-proton collider called ISABELLE at Brookhaven.
Yeah. What is ISABELLE? What does that mean?
ISA is Intersecting Storage Accelerator, so it got called ISABELLE. Eventually it was called something else, but eventually, irony of all ironies, it was canceled by the Department of Energy so they could leapfrog it and build a super collider, which was then canceled during the Clinton administration. Anyway. So that’s two generations of colliders that disappeared from my life and eventually from the US.
So ISABELLE got scrapped before it was productive?
Yeah, it got scrapped during the design and early construction phase because we had technical problems with the superconducting magnets needed for the accelerator. They were building superconducting magnets with niobium wire, and the way that they were trying to do it at Brookhaven—and this was the way it was when I got there—was with a machine that, if it were smaller, would make shoelaces, you know, flat, woven objects, a bigger one, and they were weaving these copper-jacketed niobium wires together into a matrix. That was going to be the conductor in the superconducting magnets, and it never worked right. They never could get one… They did build one working prototype on site. As soon as they tried to industrialize the process, we never saw a good magnet again, and DOE decided to cut its losses at that point. Left behind quite a legacy that turned into Brookhaven’s advantage much later while I was there. So… I’m sorry. I’ve lost the thread again. What were we just talking about before?
Well, so we were talking about how ISABELLE was scrapped in the design phase.
Yeah. So the reason I took that job was for all the personal reasons that we talked about, and also for the excitement of building a collider that could do, at that time, world-class science with colliding protons. So I worked on designing the experimental areas for that accelerator, and that’s when Sam Ting popped up again because he wanted a special built one at an empty intersection region where he could do his thing, which he eventually did at CERN. In any case ISABELLE fell apart because of pulling the funding.
I wondered what I was going to be doing with myself after that. I was still involved, though, with analyzing regeneration data from Fermilab and pi-mu atom data from Fermilab with students, not students from here but based around Fermilab. One of my ex-graduate students, Greg Bock, was at Fermilab by then with a job at the lab, and another three graduate students, two of whom worked for Mel Schwartz and one of whom worked for me, were the team that did both the pi-mu atom experiment and sort of the last phases of the regeneration experiments with K mesons that I was involved.
So analyzing that data at that point was mostly me and Greg Bock working on it. We published a paper—this was with a large cylinder filled with liquid hydrogen that we were using as a regenerator. We were doing regeneration off of protons, basically, measuring regeneration parameters over a very wide range of energies because you could get those energies at Fermilab, and Greg and I were finding something odd about them. There seemed to be an energy dependence in the regeneration probability that didn't make any sense. I still don't know the answer to it. We published it that way, and that’s the way it stands in the literature.
But meanwhile, I’m talking to my reacquainted friend Ephraim Fischbach about this and he has a brilliant idea. He was, at that time, studying, looking at the century old Eötvös experiment on weak equivalence with a torsion balance to measure the different inertial versus gravitational masses of different materials. He came up with a result that there’s no difference, which is the equivalence principle background. That’s the Holy Grail for the equivalence principle.
Why is it the Holy Grail, Sam? Why is it the Holy Grail of the equivalence principle?
Because if not, if there’s a difference and you get different results from different materials, then there is no perfect equivalence between inertial mass and gravitational mass. So Ephraim is looking at that experiment with his students at Purdue and finding, if you look at the data that Eötvös published carefully and plot them against something related to the baryon content of the different atomic nuclei, you find out that you get a fairly statistically significant signal that it isn't equivalent. There’s either something other than gravity going on or some other new physics going on.
Ephraim’s thought about the energy dependence of the data that we had taken at Fermilab had to do with this because we were underground as compared to conventional beam line experiments which are on the surface. This beam line actually dived a few degrees into the ground. The presence of that mass rang a bell with him and this Eötvös experiment data, and he started to calculate potential effects. We took these results to Frank Yang. We took them to bunches of other people to see what this could be and didn't get anywhere. But he came up with numbers out of this that seemed to indicate that this was the same thing going on that the Eötvös experiment had going on.
This all happened in 1985, or mostly all happened in 1985. In 1986, I was taking a sabbatical from Brookhaven to work at CERN for a half a year, with my family, to live in Geneva. I went to CERN in January of 1986, the same day that the New York Times had this finding which had been just published in Physical Review Letters on the front page: “Scientists Discover New Force in Nature,” because what had seemed like it was consistent with was a shorter range non 1/r2 potential, but a slightly different force with a shorter range that was causing this effect. Both in… Well, that one was all about the gravity experiments that were done in Hungary, but that paper also alluded to the energy dependence of the regeneration data as a possible related phenomenon.
Suddenly I’m in Europe and I’m famous, or at least locally available. I’m getting calls from newspapers because I’m one of the authors on this paper, and I’m getting calls from journalists who want to talk about it, or getting invited to universities in Europe to give talks about this.
Sam, did you have any idea that this would gain the traction that it did? Was that apparent to you?
I’ll tell you that one of the most exciting things that happened to me in physics was a phone call I had late one night with Ephraim in which he said he was able to make sense out of these two completely disparate experiments with the same idea.
Do you remember… What year would this have been when you got this call?
’84 or ’85, because we published that paper at the end… We submitted it in late ’85. We spent quite a long time working on it. When it came out, two experiments were done fairly quickly, one at Brookhaven having nothing to do with me and one at the University of Washington done by a nuclear physicist named Paul Boynton, which seemed to mirror this effect—I mean, seemed to come up with results that were consistent with an asymmetry. Then we were really off to the races, and lots of people got into this. I think we spent… This was not my entire occupation, but it was mostly Ephraim’s entire occupation. We spent more than a decade dealing with and explaining results that came in or trying to understand results that came in because after the first two positive ones, all the rest of them were negative.
Which told you what?
Well, it told me that there was something wrong with the first two experiments. [Chuckling] But we had a very interesting correspondence while I was at CERN and all this was breaking news. I saved the emails from that correspondence, and I wound up giving them to Allan Franklin. Do you know that name? He’s a historian of physics.
I sure do. I talked to him.
He wrote a book called The Rise and the Fall of the Fifth Force.
So there’s a lot…
How did you know Allan? How did you get in touch with him?
Princeton. He was an assistant professor at Princeton and worked at the PPA, so I knew him from those days. So what else am I wanting to tell you about this?
You're in CERN and you get this call…
No. I wanted to move on from this, so we spent a long time, including me spending a couple of years actually collaborating with Paul Boynton in Seattle. I built some equipment at Brookhaven that would help make for a better experiment. It was basically a three-dimensional magnetic shield with multiple Helmholtz coils in different directions. I did that and went there, worked with him, analyzed data with him. I even wrote the draft of a second publication, but somehow that all fell apart around that time. I’m not sure whether it was personal—I mean him and his family—or what, but I could never get him to work on that manuscript.
In any case, the evidence finally mounted up to the point where people regarded this as just a mistake in either an accidental happening in the way you plot Eötvös’s data or something wrong with those experiments that Boynton couldn't reproduce with improved versions of it, and which Peter Thieberger, who is the author of the other one at Brookhaven, didn't pursue.
So that was another thing that I did that didn't yield a new physics result, but what it did do is interesting. People got so excited about this that they worked really, really hard on it, and other people at the University of Washington (Eric Adelberger, Chris Stubbs, others) did a different kind of experiment, and although confirmed that there was no effect there, managed to push the level of… the limits on new forces in this distance range, which was somewhere between a meter and 20 meters would have been the range of this effect. They had put the error bars on that so low that a whole area of this mystery…this search for new forces was eliminated. People subsequently looked for new forces on the millimeter scale in other ways. That force that we discovered was one that didn't exist, but the fallout from it produced a lot of progress in that particular field. [Chuckles]
What was the source of the fallout, Sam? What do you think that was about?
People wanted to nail that down. It looked like… I mean we all know there are four forces in nature. A fifth force of any kind, the person with the right theory or the right experiment would get a prize for that.
So it would have been revolutionary. That’s why it was so exciting to hear Ephraim telling me for the first time that these two effects might be consistent.
And this immediately was a holy smokes moment for you? As soon as he said that, you realized the import of what he was telling you?
Yeah. And we put a lot of our time and effort into chasing that, thankfully, but it was worth it. The whole thing was worth it even though it turns out not to be the case because that’s how science advances, you know. You’d love to see that in the standard model of particle physics because everybody has a theory of where the new physics is lurking in there, and so far there isn't, after decades, any real progress, even with the Large Hadron Collider where people have looked for evidence of supersymmetry and a whole new class of particles which are partners of the particles that we know and love—absolutely no evidence from that, no evidence from searching for deviations from Newtonian gravity, although that’s still one of the potential hanging chads from dark energy. So you know, something that breaks the model is everybody’s Holy Grail, and this would have been outstanding if it had been true. [Chuckles]
So in terms of the productivity, in terms of how the science moves forward even though the fifth force here wasn’t discovered, just so I understand, does this suggest that there isn't a fifth force to be found, or simply that what you were after proved not to be the fifth force?
It’s not proof that one doesn't exist. It’s just not in the range where we looked. I mean even if you decided Eötvös’s experiment or the two experiments that were done after our paper came out were wrong in some way, it doesn't prove that there’s no fifth force. It proves only that no one’s found it so far.
What are the theoretical--
That’s the thing about the scientific method. You can always… What do I want to say? You can always prove that a theory is wrong, but you can never prove that one is right…
…because you haven't tested it under all conceivable conditions.
Sure. So Sam, on that note, it would be so useful to just hear your perspective. What are the theoretical underpinnings that suggest that the fifth force…that it is there?
That there is one there?
I think there are a number of possibilities, including some of these particle physics new physics searches that would produce an additional force. You know, parallel universes, that kind of stuff—there could be leakage from another coexisting universe on top of ours. There are lots of different smoke and mirrors kind of explanations that no one can say…because it’s very hard to do those measurements…can say that they don't exist. So my perspective is that this is still an interesting subject to explore, but not going over the ground that we plowed. It’s looking for newer technology. You know, look at LIGO. I mean, finding black hole collisions across light-years—that’s a piece of equipment! I don't know. Maybe something on the larger or more precise scale would have to be used to find something that’s subtle enough to have eluded the experiments that were tried and failed in the decade or more after our paper came out.
So you think it’s still very much worth pursuing… this line of research.
I do. I think it is, and it’s one of the reasons why we got excited about dark energy, because if there’s a possibility that there’s something wrong with the theory of gravity on some distance scales, that might explain the dark… I mean, there are a number of independent ways of detecting and measuring dark energy parameters, and they all seem consistent—you know, cosmic microwave background radiation and pulsars versus distance… I mean distance observed astronomically, and so on. Also, gravitational lensing by intermediate dark matter that you can't see is something that works and would have a bearing on the distribution of matter in the universe, most of which is actually dark matter—that is, nobody has detected that so far and had it stand up to scrutiny.
Long after this, when I’m back at Brookhaven and have done work at RHIC and wound up as chairman of the physics department, I tried to start a cosmology and astrophysics group at Brookhaven, which has never worked in that area. I had an ally in that who was a nuclear physicist at the lab, Morgan May. He and I started a colloquium series on this subject, the hot topics in cosmology. He recruited some young astrophysicists to work on this, and there is a group there now. So as an administrator, one of my proudest accomplishments is getting Brookhaven into that business.
Sam, can you tell me about some of the project that initially attracted you to Brookhaven, and in particular, I’m curious where the ISABELLE project fits into all of this?
Yes, let me go back to what brought me to Brookhaven in the first place. It was to work on ISABELLE which was intended to be a proton-proton collider with 200GeV beam energy. I was asked to lead the effort of designing the experimental halls. I did this with a visit to CERN to look at their collider’s halls and by assembling a group of high energy physics colleagues from various accelerator labs and universities. ISABELLE was canceled a few years after I took that job – a combination of technical difficulties with the superconducting ring magnets and attendant cost overruns. The US high energy community’s plan was to build from scratch in a new location a much higher energy proton collider named the Superconducting Super Collider (SSC). As I think I mentioned earlier, the SSC was also canceled a few years later. Meanwhile CERN was planning and is currently running a collider called the Large Hadron Collider (LHC). Although somewhat lower in energy than the SSC, it has the compelling advantage of having actually been built! The US ceded to Europe the energy frontier in particle physics.
What then? In my spare time I was working on a series of neutrino experiments with a collaboration, whose principal institutions were Brookhaven, U. Pennsylvania and Brown. For the longer term, the options were to join one of the groups coalescing around ideas for experiments at SSC in Texas or working on what would replace ISABELLE at Brookhaven. It was to be a pair of superconducting rings for accelerating and colliding beams of heavy ions – a nuclear physics machine called the Relativistic Heavy Ion Collider (RHIC). I chose to work on and do research at RHIC, though it was a departure from particle physics. It was interesting physics, important for the future of the Lab and working near home was a real plus.
What are some of the bigger questions for which the RHIC was designed to answer, and in turn, what new questions arose as a result of some of RHIC’s most significant outcomes?
High energy heavy ion collisions provide a way to explore nuclear physics at very high temperature (around 2 trillion degrees but for a very brief time in a very small piece of matter) and to look for a phase of nuclear matter called the Quark-Gluon Plasma. QGP was a theorized state in which at high enough temperature the protons and neutrons involved in the ion collisions would “melt” into a large plasma of nucleon components – quarks and gluons — a phase not seen in nature but thought to be the state of the universe a microsecond or so after the Big Bang and before the temperature dropped to the point at which quarks and gluons condensed into the baryons that make up ordinary matter. Groups were also coalescing around experimental proposals to search for this transition and study the properties of QGP.
And who were some of the leading figures driving this work?
The advent of RHIC attracted the interest of nuclear theorists and experimentalists (and a noticeable number of particle physicists like myself). Groups from all over the US and the wider nuclear physics world responded to the call for proposals for the initial experiments at RHIC. Eventually 8 or 9 such proposals for the RHIC experimental program were presented to the lab.
At that time, Mel Schwartz had been invited by Nick Samios to become the Associate Lab Director for particle and nuclear physics and it was his job to craft an experimental program which could support 4 experiments in the RHIC collision halls (the same collision halls envisioned and built for ISABELLE). Given the proposals that were presented, the idea was to merge the existing group proposals into a smaller number, meant to include the ideas and approaches of the original proposals.
And where did you fit in with all of this?
I was working with one of the initial proposals which would focus on leptons and photons (so-called penetrating probes) as indicators of QGP. There were three groups, each with their own proposal, going down this penetrating probes path. Mel’s plan was to merge these three groups into a single experimental team with a merged proposal.
Each of these groups had their own spokesperson and the matchmaking between them proved to be “interesting.” After a meeting of the program committee Mel asked someone who was involved in but not leading one of the groups. He asked me to take on the job being the founding spokesperson and project director of this 3-headed beast and developing with members of all the teams a design to which everyone (or most everyone) could sign on. This was not easy but fun (mostly) and we eventually built one of the two large detectors for the first round of experiments at RHIC, the other large detector is called STAR. Ours was called PHENIX – an acronym like most physics detector names, but we all like the “rising from the ashes” implication, both for RHIC rising from the ashes of ISABELLE and I suppose PHENIX itself rising from the ashes of 3 different groups and proposals.
It was clear that PHENIX had showed significant promise.
Because of the protracted mating dance, PHENIX got a later start than STAR. PHENIX quickly selected a real nuclear physicist as scientific spokesperson – Shoji Nagamiya from Columbia and the leader of one of the 3 separate proposals (not the one I had been working on). I retained the project director title and Shoji and I made a good team. RHIC started producing physics with a first run in 2000 and in the next 15 years confirmed the existence of the QGP with all 4 experiments providing results important to that and many other discoveries. As with most physics programs at the forefront of opening a new area, more questions than answers were generated. It was as if we had bumped into a previously unknown continent and were now mapping its coastline. What lay inland…? When the LHC came online several years later, they also developed a heavy ion program like RHIC’s. The higher beam energy opened up experimental techniques not easily accessible to RHIC, so this was a valuable addition to the new front in nuclear physics. RHIC has more than enough energy to explore the phase transition between hadronic nuclear matter and QGP, so the LHC with higher energy could reach higher temperatures – above the phase transition.
Sam, I want to get back to this idea of the “what if” questions with the SSC, when the SSC didn't play out, right?
So my question is, conceivably, if you 're operating at that high of an energy that the SSC was conceiving, could that have been the place where this fifth force might have been discovered? Would that be relevant for this line of inquiry?
I don’t think so. At any rate, no one was proposing to do something like this. I’m not sure that building fixed-target beams at somewhat higher energy and then doing hydrogen regeneration again would be a likely bet to see something or to solve this problem because in the intervening time, the torsion balances and torsion pendula have eliminated so much of the search space. I’m more thinking it’s something else and not a Yukawa-type potential. The size of this room is the interaction length, and I think you might get better regeneration measurements or prove that the thing that we saw at Fermilab as a function of energy dependence was also wrong, but I don't think there’s been much interest in pursuing regeneration or the things you can do with regeneration in a long time.
So if not higher energy beams, what do you see as the most productive technological advance that might get closer to discovering this fifth force?
If Newtonian gravity is not right on the cosmic scale at some low level and is the actual explanation of what looks like dark energy to us, that would beg the question of an additional force or an indication that gravitational theory doesn't work over such a length scale, all other evidence to the contrary notwithstanding. So, some deviation in gravitational forces might be the best way and you can… You know, when you're dealing with black holes and similar phenomena, you're dealing with really high gravitational energy in collapsed stars and so on, so it might not be a more precise balance. It might be something that you only get to see (if it exists), but with a better understanding of how to map the universe as a function of time. I don't know. I really haven't tried to come up with an explanation. You need a different theory in order to know what to build. If it’s not a perturbation of the 1/r2 gravitational force, something else that is possibly violating the equivalence principle or producing what we call dark energy parameters that are currently seen, depending on which one of those it is, you might build very different experiments to try to get a better handle on it. I think a lot of progress has been made in gravitational lensing in the past… Yeah, I was paying attention to this…well, since we tried to start that group in the physics department, and that’s 15 years ago.
The cosmology and instrumentation effort at the Lab is involved with LSST, and dark energy is a central element of the LSST research program.
Sam, I want to ask you about the development of cosmology at Brookhaven, right? Clearly, it’s fascinating to me how many particle physicists develop an interest in cosmology as a natural transition in their research agenda and their career.
You know, I think I know the answer to that question.
They all grew up with telescopes as their first toy instrumentation.
Yeah! You're not the first to tell me that. Absolutely. So my question is--
Right! [Laughs] So my question is why… I mean aside from the inertia of if you're happy at Brookhaven, that makes sense, but why start from scratch at a place that is not known for cosmology, has no infrastructure for cosmology, right? Why is that the more productive avenue of effort, to build something out of whole cloth as opposed to joining a group or even an institution that has deeper roots in cosmology? What’s your thinking in terms of putting this together for the next phase of your career?
Well, in part it was institutional, including institutional push-back. The push-back primarily came from Peter Paul, a senior nuclear physicist at Stony Brook then serving in the director’s office as the Acting Director during the search for Director Jack Marburger’s successor and then as Deputy Director for Science and Technology. Peter wasn’t wrong – there was a chance of overreaching here, but I thought I could see accelerator-based particle physics becoming unaffordable. It was going to continue to be a hard slog at higher and higher energies to find where and how the standard model of particle physics breaks down. And we had (and still have) a world-class Instrumentation Division at Brookhaven, and that group--
Does that include telescopes?
We built at Brookhaven for the LSST camera’s focal plane. We built a modular focal plane with CCD detectors and temperature control and much higher resolution and… That’s what we brought to the table for LSST. That high-resolution fast focal plane is a key piece to LSST’s science missions, involving imaging the entire sky visible from its location in South America many times over. It’s a sign (by no means the first) of this field emulating ground-based particle physics – large multi-institutional collaborations forming to put together the analytical and instrumentational expertise to tackle the next big physics challenge.
It’s true we had to go out and get some people who are experienced in cosmology or astrophysics along with the native enthusiasm and existing skill sets at Brookhaven, but what we could do is over time, I thought, find a way to evolve our big effort in particle physics more in that direction with the help of the Instrumentation Division. I would say even 10 or 15 years later it’s not clear that it will be sustainable, but I just thought it was a missing element that might come to be the main game that the fundamental physics talent at the lab and instrumentation talent at the lab could home in on. One thing I didn't want to do was lose that Instrumentation Division.
Not that I was in charge of it, but I just knew it was one of the crown jewels.
Sam, were the kinds of questions you were asking about your own interests—could you extrapolate to Brookhaven writ large? In other words, if you saw some areas of particle physics fizzling out and you wanted to move on to cosmology, did that suggest sort of larger even existential questions about where Brookhaven should be headed itself?
Absolutely! I mean I didn't really get into this up to my neck until I was in the Director’s Office, but all the national labs have existential challenges. Brookhaven’s strong suit is fundamental science, you know, really lab science in new areas—not just physics. There’s a powerful effort going on with the new light source in all kinds of material science and biological science. The lab pioneered a number of things that it doesn't have anymore, but which it survived. When I was in the Director’s Office, I saw Brookhaven as… Although its weak suit is applied physics compared to a number of the other national labs (Oak Ridge in particular) I didn't see… I saw Brookhaven as needing that, but not whether it was going to keep it sustainable.
What it’s always been good at is large state-of-the-art user facilities. There are many more… For every physicist that works at Brookhaven, there are probably ten physicists or chemists or biologists or whatever coming to the lab to work, get data using the lab’s research facilities. So large user facilities seem to be important, and not one, but two in two different fields. I don't think any other lab really has that. It’s why I pushed so hard, although I inherited the initial push on this from my predecessor as director—pushed so hard on getting the second…getting the new version of the light source. I’m not even sure that I was decisive in that, but I got the right people at the right time to work on it.
And Sam, I’m curious. As you're charting this transition not only for your own interest but as it is going to be impacting the lab as a whole, where is DOE in this? Do you need like… Does there need to be broader institutional support and buy-in for these major strategic shifts in the overall direction of the lab?
Yeah, there does need to be. I think, though, it’s actually driven by the labs and not by the DOE. I think DOE’s heart is in the right place and it knows how to track or support experiments…big initiatives, rather. I’m thinking right now about Jim Yeck. Do you know who that is?
I’ve heard the name, yeah.
He was the federal project director, working at DOE for RHIC. Then he moved on elsewhere and now he’s… I got him to come back to be the assistant project director for this new light source. People at the lab have now gotten him back a third time to do the next big thing, which is the Electron-Ion Collider, a spinoff of RHIC. That has just gotten the critical decision on siting an electron-ion collider, and it’s going to be at Brookhaven. But that took a collaboration between Jefferson Lab and Brookhaven, both labs being well-positioned to compete for it.
So when we first started to talk about that, I was still director then. I called the director at Jefferson Lab and said, “There’s either going to be one Electron-Ion Collider or none in this country,” because you can't afford to build two, “and we need to work together on this wherever it goes.”
What kind of numbers are we talking about budget-wise? This is, what, a $10 billion project?
No. Probably half that or less. [Interruption] So I made a pitch to him that we had to cooperate on doing this. We, in the end, put together an international steering committee, including lots of people from both labs. We had a lot of the physics equivalent or the accelerator equivalent of bar fights over various design details and various big issues about how to build this thing. Accelerator physics is another strong suit of both Brookhaven and Jefferson, and the fact is that we had more stuff on the ground than they did in the form of RHIC. So I knew it was going to cost less to do here than there, but I wasn’t confident that cost would be the driver.
You know, a senator can zoom in at the last minute and cut a deal with the administration. Sen. Everett from Illinois appears to have helped Fermilab get sited in Illinois—by agreeing to support Lyndon Johnson’s Great Society legislation. I worried about something like that affecting the outcome.
What I always assumed would be the savior of Brookhaven in the long term was a fundamental physics user facility and…let’s call it a material science based user facility. The lab already had a light source—in fact, invented the modern light source, the synchrotron light source—and it already had RHIC. Both of them had a future if we could pull off that hat trick, and in the end, it seems like the lab did it and it’s taken until just now to make that happen. So just not waiting for the good news to come in, but proactively figuring out who needed to be on board at other labs to do what is how all these things happen.
And Sam, did you see that as your primary mandate as lab director from 2006 to 2012 to anticipate and to stay ahead of the curve? Is that primarily the job?
Yes, I think so. It may not be the way DOE sees its relationship to the national labs. I think all those technical innovations together with changing scientific priorities, those come from the ground up and not from a master plan in the DOE Office of Science.
The DOE programming leadership is by and large committed to supporting the science mission within federal budget constraints and recognizes good initiatives when they see them. Every year the Office of Science calls in the leadership of each laboratory to give a presentation for the future and a strategic plan foreach lab. Every year the Office of Science has this pile of strategic plans at the laboratory level but doesn’t then seem to develop DOE level policy and planning from that input. Everything seems to me to be done piecemeal. Not that I think it’s a bad thing! I think the long-term direction and priority should be driven by the scientific and technical developments.
Right. What do you see as your… What are your key achievements as laboratory director?
I think that’s it, actually. We also tried something during my tenure there that was more internal. Also in the name of preservation of the lab, we tried a variety of ways to change the culture there to make it more collaborative, more efficient, more strategic and safer. I had consultants helping us do this and we had town hall meetings in the auditorium a bunch of times. I learned how hard it is to get people to change behaviors that they’ve learned over decades. Some of it took hold, but much of it in the face of “Well, but we always did it this way.” It’s looking backward all the time to the [mythical] good old days. It was at best a good first step.
When I became director, I arranged for the director and the associate directors to participate with some outside consulting in a reading course on business strategy—you know, something like trying to learn a foreign language in middle age. But it was, I think, helpful in building coherence in that group, and it, I think, put some people who are entrepreneurially and academically inclined—it put some of them in positions to think more about this and do things that had some benefit. It’s an institutional process, not a particular outcome.
So I guess to continue on with that question, what are the things that you set in motion that continue to define Brookhaven’s research agenda even eight years later?
I think it’s what I did to keep the electron-ion collider alive when there was a lively debate in the nuclear physics community about the next big scientific initiative. So having the idea that maybe we could get two major user facilities in different fields and build on those—I mean, the two that are in progress right now (the new light source is running and the electron-ion collider is about to begin construction). That vision/plan won't be a reality till probably 2030 at the earliest. DOE is heavily investing in Brookhaven on both. I think you have to look at a national lab in two ways – with a mission (science and technology discovery and innovation) and as a business based on its strengths and capabilities (diverse fundamental science and accelerator technology). Call it the BNL family business. You have to tend to the family business or nobody’s doing the scientific discovery out in Upton.
Right. [Chuckles] When 2012 came along, when did you know it was time to step down? How did that play out? Is that a normal time of tenure for laboratory director?
Nowadays it is, although across the labs and back in the day, whenever that was, some lab directors served longer terms, some for 15 or 20 years. Now six years or seven years is about as long as people serve, and I think I know why. It’s the interaction between the contractors and the Department of Energy, and the person in the crossfire is the lab director. The lab director is accountable to DOE for meeting all the metrics but does not have control over the purse strings and cannot solve problems at the lab level without DOE approval. This in turn is due to DOE’s accountability to fund work at the lab as appropriated in the budget. So, if I want to solve a problem over here and I have to use money from over there to do it, I can't do that without… You know, I won't say an act of Congress, but in fact it is; without a very long conversation that will eventually come up against appropriations laws. So it’s very tough. You're given a lot of responsibility and not a commensurate amount of authority. That’s the burnout factor, in my view. I think it just becomes a very hard slog after a while and you forget all the daydreams you had about being able to run this whole thing. If you're lucky, you accomplish something. But when a particular field that’s a major part of some national lab’s program starts to lose funding because the DOE’s assessment is that it’s been taken over by Europe or Japan, or because there’s no more affordable gain left in it, that lab has an existential problem.
Right, right. And your subsequent position as senior advisor. Do laboratory directors have like a kitchen cabinet? Is that the kind of role where this is here where you're still there? You're providing insight. You're providing perspective based on your experiences. Is that what that role essentially is?
No. I’m sorry to tell you that that role was a non-role. That was just some way to continue affiliation with the Director’s Office but it didn't really provide much…or asked for much advice by the current director. Directors, they’re like CEOs. I did the same thing. I didn't expect that role when I was given it, and it left me feeling not useful at the lab. You know, whatever I had done before might speak for itself, but I was no longer not only in control, but I was no longer needed at the table. I know that my predecessor didn't consult with the director he replaced. I didn't consult with him. The present director didn't consult with me, although we did work closely together – he was the deputy director for science and technology throughout almost all of my tenure as director. It’s just a maybe valuable resource, but it wasn’t called on during my year as senior advisor. On the other hand directors do often have people at the lab as informal advisors in specific areas.
Well, maybe on the positive side of that, it did free you up to go back to what you had gotten into the business in the first place for, which was doing science.
In a way it did. It left me with a smaller domain of people who were all doing the same science that I had spent the last decade and a half doing, so that was good.
Eventually, when I retired from the lab, I got into something completely different at Stony Brook University. I think it’s more economic development than it is science and technology.
Yeah, it’s an interesting appointment, the Technology and Society Department.
[Unintelligible] Yes, but appropriate to my goals at that point.
So this is beyond physics.
What I’m doing with that is to try to help rural communities that are off the grid in Africa. Why in Africa? Well, we happened to see an opportunity and get a suggestion from the guy who runs the Turkana Basin Institute in Kenya, Richard Leakey. I know Richard from here because he has a joint appointment at Stony Brook, and one of my oldest friends from Stony Brook is the director of this institute. A colleague of mine—Ben Hsiao from the chemistry department at Stony Brook—and I sat down with Richard Leakey and we came up with an idea to do something we thought might be useful. I’m still working on that.
We’re fundraising, trying to make something happen that would help people at the bottom of the socioeconomic pyramid develop the skills and tools to realize their own aspirations. We’ve assembled a small interdisciplinary team and that’s what we’re trying to do.
It’s another common theme, Sam, of, you know, particle physicists of your generation emphasizing the importance of reinventing yourself to apply your research and your expertise in new areas. It’s fascinating how… I mean, it’s fascinating both in terms of what it says about the state of high energy particle physics, and it’s also interesting in the sense of how physicists, first of all, never really retire, right?
They just… [Laughs] It’s an amazing thing, right? But there are new— opportunities. There are new places where you can continually make an impact. It’s a special thing to hear all of these perspectives.
Yeah. As a retiree I think about this with two aphorisms in mind. One is that there’s no shortage of work for people who don't need to get paid, and the other is that you can do wonderful things if you don't care who gets the credit. So that’s the only portfolio I’m taking into this job. It’s not even largely R&D. I mean there are things we can do that are applied…or tweaking appliances that will work with direct current or survive in arid northern Kenya or whatever, but that’s about as esoteric as the science gets. It’s more about people, actually, which is how I spent the end of my physics career; it was basically more about people because, as a friend of mine said, “You're still doing physics, but you're using different instruments,” by which he meant people.
That’s right. That’s right.
So, it’s more of a carryover from what I did as a department chair or director, whereas I got into it thinking it would be more of a carryover from my interest in science and technology.
Well, Sam, now that we’ve gotten to the present day, I want to ask you for the last portion of our conversation a few retrospective questions that assess sort of your overall recollections in the field. The first is it sort of straddles both a retrospective question and a forward-looking question, and that is you were—I don't know what the right word is. Serendipity? Lucky? Good timing? But you came of age intellectually, right, at some truly exciting moments both in terms of how Sputnik captured the American imagination and really supercharged your own education and career right to the point when you decided to focus on particle physics at arguably the most impactful time in the entire 20th century, right at the time in your career when it was sort of most useful. You weren't too young, and you weren't too old right when these things were happening, right? So to use your powers of extrapolation, to the extent that you were a beneficiary of being there at the right time, do you see a second golden age in particle physics in the 21st century? What would it look like to get there?
I’m not very optimistic about it if we’re talking about particle physics as it’s been practiced because to actually take theories in current play to a point where you can test them would take energies that no one at present knows how to create on the Earth.
You mean even SSC times ten.
Right. If you talk about string theory, which we mentioned earlier, it seems like all of its predictions are out of reach of anything that I can extrapolate from the work I’ve experienced during my career. It’s a lack of imagination on my part, but it seems to be a widespread lack because no one’s got an idea for how to test most of the stuff, including the people who invented it. I know theoretical physicists who say it’s not even science because you can't test it. So, I don't know how to take us to… I don't know what it would take to do it. Maybe it’s bigger and better telescopes or other probes like LIGO of the universe. There’s enough energy there and enough interesting sources to look at or to watch collide with each other to maybe make progress on that. I don't know. I’m sorry to have this pessimistic view of the field that I’ve been in for so long, but it’s actually been stuck for a long time, too. In fact—
But is it possible that it’s been stuck because all of the fundamental discoveries have already been made, or is that not even how science works? You never think that you’ve sort of reached the end point on anything.
Actually, at the end of the 19th century, Lord Raleigh said, “Well, we’ve figured it all out.”
Then came 1905, you know. So that’s a dangerous game to play, prognostication, especially about the future.
So if the going assumption is there’s always more to find and yet you're pessimistic that we have a pathway to get there, what do you think the more important element is? Is it advances in technology, or is it the next Einstein, the next Feynman, whoever the next giant is, genius, visionary, whatever you want to say, that’s going to think of things in a novel way that no one has thought about before that, absent technological change, might actually change the paradigm and reopen that possibility for a new golden age in particle physics?
I took a course at Barnard when I was in college. It was basically a history of science course taught by a physicist named Dan Greenberg, and he made a point that stuck with me this whole time, which was that there’s this interesting interplay between ideas and instrumentation. If Kepler had had modern techniques and modern astrometric data, he’d never have found Kepler’s laws because there are all kinds of second and third order effects that mess it up, and if you have precise enough data, you can see that. So, it’s hard to untangle the two.
I think the paradigm that’s being pushed right now, which is string theory or super string theory, is… I don't see any… This could be just from lack of attention on my part, but I don't see any other pathways that are being blazed in new ideas. And the instruments we have right now are not capable of doing more than looking for better data or contradictions to the current model of the universe that we have. When we’re at a point where that interplay between ideas and verification through instruments doesn't seem connected anymore, something… There’s another quote from Einstein. He said that solving a problem takes a higher level of intelligence than the thinking that got us into the problem in the first place. You know what I'm saying?
Or what he was saying? [Chuckles]
Something that connects what people can actually do and what ideas people can actually have seemed like it’s not close enough without something on a different plane that re-forges that ability to have that interplay. I don't know what that is, but… I don't have any buts. I don't know what that is.
Mm-hmm [yes], mm-hmm [yes]. Well, by force of nature, I have to end discussions on a positive note and so I must ask, looking forward, what are the things… Besides… It’s wonderful to hear that you can put your expertise to sort of more humanitarian, on-the-ground uses, right? But more broadly for physics as a whole, what are you optimistic about? Where can the various fields be headed that would be foundational for the next generation of physicists coming up?
If people finally understood the century-old question of superconductivity and how it actually works such that it incorporates what people are able to measure about high-temperature superconductors and maybe extend that, that could have a revolutionary impact on the planet in terms of transport of energy, extracting energy from wind, and so on. That’s more about the quality of life on planet Earth, which we’re busy trying to destroy right now. But it’s not… And a lot of people have worked on this problem and it’s not solved. That’s something I think that’s within the realm of current theory and experimentation, and that work still goes on. The light source at Argonne, the new light source at Brookhaven are both very valuable tools in pushing that forward. It sounds a little bit too much like applied physics maybe, but in fact, there is some deep science that we don't understand. I mean, how does superconductivity work?
So there are questions to be answered. They just don't seem to have the grandeur of, you know, how does the universe work? It’s a little piece of that puzzle, but that may be… Until some higher level of thinking comes along, that may be what we do. And it certainly has benefits both in new physics knowledge and practical applications. We need to do something to save the place or we won't get the chance to do the higher level of thinking in the future. I’m sorry. Best I can do.
That’s great. That’s great. It’s been really great talking with you today. I want to thank you so much for sharing your perspective and insight with me. It’s been a pleasure.
I enjoyed talking with you. Good questions. I like your questions.
Great, great. Mission accomplished!