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Credit: Lawrence Berkeley National Laboratory
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Interview of Murdock (Gil) Gilchriese by David Zierler on April 5, 2021,
Niels Bohr Library & Archives, American Institute of Physics,
College Park, MD USA,
For multiple citations, "AIP" is the preferred abbreviation for the location.
Interview with Murdock Gilchriese, Senior Physicist at Lawrence Berkeley National Lab. He discusses his contribution to the major project, LUX-ZEPLIN (LZ) and the broader search for dark matter, he recounts his parents’ missionary work, and his upbringing in Los Angeles and then in Tucson. Gilchriese describes his early interests in science and his undergraduate experience at the University of Arizona, where he developed is expertise in experimental high energy physics. He discusses his graduate work at SLAC where he worked with Group B headed by David Leith, and he describes his research in hadron spectroscopy. Gilchriese explains his postdoctoral appointment at the University of Pennsylvania sited at Fermilab to do neutrino physics before he accepted his first faculty position at Cornell to help create an e+/e- collider and the CLEO experiment. He discusses the inherent risk of leaving Cornell to work for the SSC project with the central design group, and then as head of the Research Division. Gilchriese describes his subsequent work on the solenoidal detector and his transfer to Berkeley Lab to succeed George Trilling and to join the ATLAS collaboration. He explains the migration of talent and ideas from the SSC to CERN and discusses the research overlap of ATLAS and CMS and how this accelerated the discovery of the Higgs. Gilchriese describes his next interest in getting into cosmology and searching for dark matter as a deep underground science endeavor, and he explains why advances in the field have been so difficult to achieve. At the end of the interview, Gilchriese describes his current work on CMB-S4, his advisory work helping LBNL navigate the pandemic, and he reflects on the key advances in hardware that have pushed experimental physics forward during his career.
Okay. This is David Zierler, oral historian for the American Institute of Physics. It is April 5th, 2021. I'm delighted to be here with Dr. Murdock Gilchriese. Gil, it's great to see you. Thank you so much for joining me.
Thank you, David.
To start, right to basics. I know you go by Gil. How long has that been your nickname?
[laugh] It's been my nickname for about 50 years. So when I-- my parents called me Murdock, but then I went off to actually to graduate school, I said, “Well, you know, Murdock's kind of a challenging name.” So, I switched to Gil.
Are you named after someone? Is there a Murdock in your family?
No, it's a Scottish name. My father was very enamored with his ancestry in Scotland, and so it's a Scottish name. So, he gave me a few other names, which maybe I should have used. Gordon and Douglas are my middle names.
Ah, there's the G.D. from your CV.
Right, right. So anyway, Gil is a lot easier to say than Murdock, so.
[laugh] Gil, on a more official level, what is your title and institutional affiliation?
Yeah, I'm a senior scientist, senior physicist, at Lawrence Berkeley National Lab. And I've been at the lab since 1990, the beginning of 1990. So quite a few years.
Now, as a senior scientist, what does that title connote?
So that's the laboratory equivalent of, as close as you can get to tenure at a national, DOE national laboratory. So it's similar to a tenured faculty position at a university. And so that's what it primarily is. It means you have the ability to potentially, if you figure them out, lead research efforts and have a group of people working for you, for example.
Gil, to give a sense both of the hierarchy in the organization, who reports to you and who do you report to, and where is your work overall in the lab?
Yeah so, I'm a few layers below the lab director. So, there's typically an associate laboratory director that covers multiple areas of the lab, and there's a division director that covers, in my case, the so-called physics division because of the history of the LBL. The LBNL. And I report to that person. So, I'm a few layers below the lab director. And then in the senior scientist position, typically there are postdocs, other kinds of scientists, research scientists or staff scientists or other types that report to the senior scientist. So, it depends a little bit on what you're doing and how many people are needed to carry out the research, but that's what you do.
Gil, a question we're all dealing with right now. How has your science and the lab in general dealt with the pandemic and remote work over this past year-plus?
That's a great question. So overall, the laboratory has done very well I would say. And there have been, at least as of last week, there have been 48 cases of laboratory employees unfortunately getting COVID, but none of those have been cause by associations or contact at the laboratory. They've all come from the community. And so that's one of the best records, I'd say, in the country. All those people are fine.
And so the lab is-- When COVID hit, it basically went back to a few hundred people to just sort of keep the lights on, so to speak, and then over time it gradually added, and it got up to about 1/3 of the regular population on a given day. And then when the COVID took off a few months ago, that was backed off to about 1/4. So, the typical occupancy at the lab now is about 1/4 what it was pre-pandemic. But people are clever, and some people come in in the morning and some people come in in the afternoon, and some people come in on Saturday. So, there are about 2,000 people a week, different people a week, that come to the lab. And before that, it was more like 4,500. Before COVID. So I actually—maybe this is more than you want to know—I took a brief few months, if you look at the CV, and tried to co-lead how the lab was kind of organized itself to get back to work under the circumstances. And so, I worked with the lab director and the operations lead and there was a whole crew of people trying to figure out, what do you do? [laugh] And it worked at the operation side of Lawrence Berkeley Lab, the people who you don't see often in research, but maintain all of the stuff and systems and so on, they're really fantastic. So, it worked out very well, I would say, compared to maybe other places. And it's continuing to work out pretty well.
And Gil, what about for you and your own research? To what extent is remote data analysis--
So, one of the projects that I was involved in at that time, I was the project director for this dark matter experiment called the LUX-ZEPLIN, the LZ, which is an acronym of acronyms. And it's an experiment that's a mile deep in a former gold mine in South Dakota. And we were just at the peak of installation, that is putting all the parts together, in South Dakota when COVID started. And so the number of people that could go there and actually work on putting things together was severely restricted. It was an international collaboration, so we had people, say, from England and Portugal who would regularly visit, and they would stay for months and help. But they couldn't come, and we had fortunately hired some local people to help us put things together, and of course they could do it, but it was very challenging, and things got slowed down a lot. For a while, they got slowed down completely because the laboratory in South Dakota, like many places, shut down for a while. But then it slowly came back up, but it's been very challenging over the last year. There's been steady progress, but not as fast as people would like.
And now that we're starting to hopefully peek around the corner of the pandemic, what are the things that you're looking forward to jumping back into? What things are on pause and what things are going to be just sort of brand-new? From scratch?
Yeah so, I think what's been on, sort of on pause, are all of these projects that I and other people at the laboratory are involved in. People have done a great job in trying to keep things going by Zoom and email and it's really quite remarkable. Nevertheless, there are things that you have to do in person and so we're looking forward to getting back to those things. And being able to travel in particular, which has been very, very challenging to get permission to travel or people want to travel. That's really the key, because scientists like me, where their things happen all over the world, in Europe, in South Dakota, Antarctica, Chile [laugh]. So you have to be able to travel, and within the United States, typically you work in large collaborations so you visit, you have to visit your collaborating institutions once in a while. So that's the part that's really been missing, I would say, that has impacted things the most.
And Gil, for you as you look to the future, is your work of the nature, where automatically, if you have the opportunity to go in every day, you would? Or are there aspects of your job where you can do part of your work remotely, going into the future?
Yeah, so for me, you know, in my current old age, so to speak, yes, I can do most of my work, almost all of it, in fact, remotely. And I was working remotely part time even before the pandemic. But the thing that you can't do is the personal connection, or we have things that are being built at various companies or institutes and typically you would go there and kick the tires, right? And that's really, really important to do. To establish those personal connections that, yeah, you can try to do that over Zoom, but it's very challenging.
Right, right. Well, let's take it all the way back to the beginning. Let's start with your parents. Tell me a little bit about them and where they're from.
Yeah, so my parents were both born outside the United States. One was born in Canada in a little town near Toronto, but came to the United States when he was about three in the 1920s. And my mother was born in what is now Malawi in Africa. And which was called something different when she was born. It was Nyasaland. And she eventually came to the United States when she was going to college. Nursing school in fact. And so, both my parents were born outside the United States, but they came to the Los Angeles area for different reasons. So that's where I was born, in Glendale, California.
How many generations do each of your parents go back in respectively Canada and Malawi?
Well, in Canada it goes back quite a ways, partly. And the, I don't know if it's true, but the story that I was always told as a kid is that the Revolutionary War—they were loyalists—and so they didn't want to stay in the United States so they [both laugh] so they went to Canada. So probably is true. And then I think there was other people from Scotland that came to Canada later. And my mother's side was also from Britain, from Cornwall. And her father was a medical missionary in Malawi, and so-- But before that, it's all in Britain in various parts of Cornwall and England and Scotland.
Was that area a British colony?
Yeah. It was a British colony, and my mother's father was a-- he established places where people could receive medical care, and also religious instruction in fact. But there are some really interesting stories like, you know, leopards under the bed and [both laugh] monkeys in the house and having a father who had to-- there was a rogue elephant, had to kill an elephant.
How old was your mom when she left?
She was about 18.
Did she ever return?
No, never returned.
Where did your parents meet?
They met in LA, in the vicinity of Los Angeles. Eventually, they got married and they spent a year as missionaries, actually, on the Navajo reservation in Arizona, northeastern Arizona, and then came back to Glendale. And so that's--
What were your parents' subsequent professions?
My mother was a nurse forever, and my father was mostly unemployed, actually. He was self-employed for most of his life, or not employed. He was an amateur historian of the American west, and he just had a fascination with this from his teenage years, and one of the things that's not well-known is that a lot of the people who live, say, in Arizona or New Mexico or wherever, move to Los Angeles in their later years. And so he would interview-- he would go meet these old people, and there are museums that he would go to. Finally, he connected with the secretary for Wyatt Earp, who is a well-known name, and that person eventually gave my father all of the stuff that he had gotten from Wyatt Earp. Including hand-drawn maps of all of his gun battles.
Diaries, letters. In principle, one of Wyatt Earp's revolvers, you know, badges, sheriff's badges and things like that. After this person died. And so, my father had that collection, but he also collected books on the American west and collected material on the American west, but you know, it was more like a hobby because he wasn't employed by anybody to do this initially. About 1963, he actually got employment, but in Arizona at the University of Arizona as a field historian—part of their system was to collect material about the history of Arizona, and he'd already started doing that as an amateur, and so that's what he did.
And the family moved out to Arizona at that point?
Yeah, we moved when I was about 13, moved from Glendale to Tucson. And so, he was employed there. My mother was a nurse at a local hospital.
Gil, when did you start to get interested in science?
In high school. So I got really interested, I remember this distinctly, when I was a sophomore in high school. And I started, it's both through the courses in the high school, which were pretty typical, but I also got interested in high energy physics by reading books, you know, popular books on physics in those days. This was in the ‘60s. ‘60s, early ‘70s. ‘60s. You know, I remember, one book that I remember, if you know David Livingston?
He was a-- yeah. So, he wrote a popular book and I read that book and I said, “Hey, this is really great.” I remember this distinctly – it was really great stuff. I'd sort of like to do that, and for whatever reason, that inspired me to take physics courses and whatever I could do at the high school level. And calculus and all this stuff. And so I really knew from when I was like 16 and I was reading about quarks and from something from Murray Gell-Mann or something. And my god, this is really great stuff. So that's when I really started to have an interest.
Between cost and proximity, was the University of Arizona really just an easy decision for you?
Yeah. So, it was cost. My parents were not rich. And my father worked there…
Did you get tuition as a --
Yeah, my father worked there, and so yeah, and I think one of the reasons he went there is because of that. And yeah, so that was it. Also, so... And in fact, looking back on it, I'm sure-- University of Arizona was really out in the boondocks [laugh] in those days. It was before all of the-- Being a center for astronomy was, it was just starting to be that, and so that whole culture was just being developed.
Did you declare a physics major right away?
You know, actually I didn't. And I got into-- I started off in nuclear engineering, and then I had a professor who said, “Well, you know, nuclear engineering just does nuclear engineering, and you sound like you're interested in more than that.” So, I switched to physics, which I hadn't quite appreciated what the difference until I found out. And then I switched pretty early, as a freshman or a sophomore into physics.
Gil, did you gravitate more towards the theory side of things or experimentation as an undergrad?
All the way.
All the way, yeah. Theory is—certainly in those days, and still—it's the smartest people go into theoretical physics. And you know, I was pretty smart, but I was not that smart. And of course, it takes you a while to figure that out. But I was really attracted to building things, and so I started working in physics labs when I was a sophomore. And you know, they asked me to build stuff, right? And I didn't know what I was building, but I started building things and then it graduated to helping. There was a very small high energy physics group at the University of Arizona, and they had an experiment, cosmic ray experiment, on a local mountain which is about, I forget, 9,300 feet high. So, this required building some instrumentation for that experiment and going up the mountain and putting it together. And so, I remember that. And building the instrumentation was a lot of fun. And going up the mountain is a different kind of fun, because you had to worry about bears or lightning was the biggie. We got hit by lightning and that wiped out a computer. I do remember that. The building got hit by lightning. So that's where I learned, you know, I really felt satisfied, because by the time I was a senior, I was building things, I was working on my own, I was actually writing computer programs in Fortran in those days. Running on old, in those days, the best computers. You know, CDC something, right? And so I was going that. I was sort of working alone, you know, after a while. People would say, “Well, we need this done, so go off and do it.” And I would go off and do it. Had an office in the laboratory as a senior. And it was a lot of fun.
Gil, were there any professors that you were particularly close with or were very formative for your intellectual development as an undergraduate?
Yeah, there were three professors there. And the most distinguished one who's no longer alive was a gentleman named Ted Bowen. And they'd all sort of been involved in, had learned in in some cases, Berkeley actually. And later as part of my undergraduate work, they had an experiment at the Bevatron at LBL, which was still running in those days, and so I went out to Berkeley. That was my first visit to Berkeley as an undergraduate working for the University of Arizona on this experiment that they were doing there. And so that was a fun experience as well, as you can imagine.
What was the experiment? What did you do for it?
So you know, I pretty much was a body taking shifts. The experiment was some kaon back scattering experiment, if I remember correctly, off a hydrogen target. And I don't remember much about it, honestly, except for working in the Bevatron and changing gas bottles, or doing all the menial things you do when you're an undergraduate. But I remember the experience going there, and the fog rolling in, you know? You don't get a lot of fog in Tucson. [laugh] So that was very interesting.
Gil, on the social side of things, being an undergraduate in the late ‘60s and early ‘70s, did University of Arizona, did it see a lot of campus protests, that kind of thing?
Yeah. In the high school too, I would say. There were both, I think, protests related to Vietnam of course and also the whole, you know, racial awakening, if I could call it that? It was also very, very visible there. Arizona was not, unlike Berkeley, was not a hotbed of protest, however. It had a much more conservative student body, and so it was quite interesting to go to Berkeley [laugh] and see the difference. At least very briefly, at least, it was quite interesting.
Gil, when you were thinking about graduate programs, how well-defined was your interest and identity as a physicist? In other words, did you know what professors you wanted to work with? What programs you wanted to work in?
No, I didn't know what professors, but I pretty much knew sort of where I wanted to go. And so you know, I applied to a bunch of places, and I don't actually remember other than two. I applied to Stanford and I applied to Berkeley. And the reason was, there were accelerators at Stanford and certainly a history of accelerators, because I'd seen it in Bevatron in Berkeley. And so that was the major motivation. Go someplace that's connected with an accelerator, physics atmosphere.
So, the plan was to apply to a physics department but then work at either Berkeley Lab or SLAC?
Yeah. Although, you know, when you're that age, it wasn't quite so clear as that sounds like. But basically yes. I wanted to go some-- the professors that I worked with as an undergraduate said, “Well, you know, if you really want to do this, then you've got to go to an accelerator laboratory that has experience with accelerators and doing physics.”
Why the focus on accelerator physics, Gil? What was captivating about that to you?
It was partly because that's pretty much where the field was. At that time. And you know, the things that came later, like non-accelerator experiments, they were really tiny in people's views. And so that was a time when accelerator-based experiments were the place to be. And so, I applied to Berkeley and applied to Stanford, and if I remember correctly, I got into both, but I picked Stanford, and honestly, I don't quite remember why Stanford as opposed to Berkeley. But I think it was--
Did you check out Stanford at all?
No, not really. I think it was mostly because Berkeley was-- accelerator-based physics was clearly on its way out, right? And Stanford wasn't. Stanford really was, you know, in the ‘70s, was “Whoa,” that was a great place to be. Yeah. So that was pretty much the deciding feature.
Did you know at all about the divide or the tensions between the physics faculty and the SLAC faculty?
No. No. And in fact, when I got to Stanford, even-- I'm a lowly graduate student, right? I didn't see this divide at all. And in fact, I didn't see any kind of division. It was great. There were all these people, you know, and I was basically interviewed, right, by all of the group leads at SLAC and some of whom were professors at Stanford. And it was fantastic to talk to these people. It was just amazing. You know? The collection of good people that Panofsky put together, right, was amazing.
Gil, coming from a big state school, Stanford is obviously a step up. Did you feel well-prepared relative to some of your fellow students who were coming from maybe places like Princeton or MIT?
I struggled some. I did okay. You know, fortunately at Arizona, there was a lot of flexibility, and I had taken graduate courses in mathematics, for example. In group theory and stuff like that. So, I'd seen a little bit of the rigor from graduate school, but not as much, so you know. I did okay, but I wasn't... I was clearly not as well-prepared as some of my peers. But it was okay. I was holding my own. Wasn't hanging on by my fingertips, quite.
What was the initial group that you joined at SLAC?
So, I joined a group, what was called—you know, they used to be by letters, as you may know. So, I joined group B, which David Leith headed, who was a really young physicist. He wasn't much older than me, actually. But he had a very dynamic and large group who were primarily building things, building experiments. In those days, what amounted to a big experiment. Today it's not, of course, so big. So he had one of the largest groups and I was attracted to this partly because, you know, it's just, it was personal in some way? And there was a lot of building, instrumentation work going on, and that's what I had done previously as an undergraduate, and so it was a fit. You know, looking back, you could say, “Well, you know, you screwed up—" Or I screwed up. Should have joined Burt Richter's group and worked on SPEAR and discovered the J/psi and you know, I could have well done that, but I didn't help discover that. But I will say, in terms of education, it didn't make a whole lot of difference frankly. SLAC was an incredible place to work in the 70s. It was just--
And did you find yourself spending most of your time at SLAC? Or how much were you in the department?
So, I spent as much time as I could at SLAC. Because I liked it, you know? It wasn't for me, there wasn't any actual physical work going on at Stanford. It was all classes and studying. And all the physical work was at SLAC. And so as soon as possible, I bailed out of Stanford [laugh] and stationed myself at SLAC, and so that you could be in the laboratory and actually build stuff.
And what are the mechanics in terms of having a thesis committee? Having a graduate advisor and ultimately a thesis committee, if you're spending all of this time at SLAC and not the department?
Yeah, it wasn't a problem. The integration was pretty good, and so the only problem with my thesis was that the miserable experiment that we were working on took forever.
This was what? The kaon scattering?
It was a large-aperture spectrometer for hadron spectroscopy. And so, it involved a solenoidal superconducting magnet, liquid hydrogen target, and a bunch of spark chambers and proportional chambers and also a dipole magnet it was always, for those days, it was quite complicated. And it did not come together quickly. And so what happened was, people said, “Well, you've got to graduate, so let's concoct an experiment [laugh] with what we've got.” And so that's what happened. Basically, by just using the dipole magnet and doing some kaon scattering experiments, which you know, frankly they're not very luminous or memorable at all. But just doing the experiment, doing the analysis, and writing up the thesis was of course a very valuable thing.
Gil, what were some of the theoretical components to kaon scattering that might have been relevant to the experimental work?
Yeah, not much actually. And looking back in hindsight, they were trying to test various hypotheses for all this complicated-- You know, hadrons are very complicated objects, and so they're always kind of duality and all of these kinds of concepts that were prevalent in those days. But if you look back from today, it was eh, you know, it wasn't very relevant, let's put it that way, to the future of the field. Relevant to my future [both laugh], not so relevant to the future of the field.
SLAC, of course, during these years had many eminent visitors come through and check out what was going on. Who might have been interested in the kaon scattering experiments?
Almost nobody, you know? Almost nobody.
Feynman wasn't interested?
No, Feynman wasn't interested. He was all in, you know, he was appropriately interested in the J/psi, and before that of course in the electron scattering experiments that helped show that quarks exist.
What about Bjorken?
Bjorken was somewhat more interested. He was very broadly interested, and in those days, was a young guy. But you know they frankly, what I did was generated to get me to graduate [laugh] and it didn't have a lot of interest from the theoretical community.
Who was your advisor and who else was on your thesis committee?
So David Leith was the advisor. And Fred Gilman. Do you know Fred Gilman?
I know him well.
Yeah, he was one of the people on the committee. I think Stan Wojcicki was on the committee, who I later worked with, or for. In my different phase. I remember Fred Gilman asked me a question that I screwed up. [laugh] But you know, I still escaped.
I'm sure he was very nice about it.
Oh, he was very nice about it. Yeah. Fred is a very nice man.
Gil, who were some of your contemporaries at SLAC?
Yeah, so I don't know who, they're people who basically went off in other directions. So, Jim Siegrist wasn't exactly a contemporary. He worked off-- we didn't work in the same group, obviously. And he was a younger person, little bit younger person. There's a physicist who is now at SLAC, Rafe Schindler, who was also sort of a contemporary. But a lot of the people that I worked with went off, and I don't know what happened to them. They didn't stay in the field.
Gil, of course you weren't in Burt Richter's group, but I wonder if you had a front-row seat to all of the excitement in November 1974?
Sure. Oh yeah.
What was that like as you were witnessing these events?
It was amazing. The auditorium was full, the announcing of these things, the speed with which they came out. In those days, I remember seeing-- In the thing that I did, we used in those days pretty fancy computer graphics to look at event reconstruction, and had these big consoles, right? Because there weren't-- you didn't have powerful computers. I remember Richter sitting at one of these as part of a publicity thing, in the paper. But the thing that you most remember is the speed of the results coming out, and how the auditorium is filled. And okay, a little later it's filled up again, you know? And so, it's really quite amazing. And you could sense that this was really, as I said, a revolution in the thinking. It was really quite apparent.
After you defended, what opportunities did you have? What postdocs were you looking at?
So, I wanted to get away from SLAC just to broaden my horizons, and I didn't want to leave the country. So that pretty much-- and if I wanted to do accelerator physics, that sort of left two alternatives, right? Fermilab or Brookhaven. Fermilab in those days was much more, you know, wide open. And I also wanted to switch to something that was different from what I had been doing. Also, there was a feature that a student graduated a couple years before me, Brig Williams, University of Pennsylvania now. And so, he invited me to apply to the University of Pennsylvania doing neutrino physics at Fermilab basically. Along with Al Mann, who you surely are aware of.
Al Mann was the head of the group. And I said, “Well, you know...” I didn't really quite understand the field. I got to say it takes me forever to understand things. So anyway, so I accepted the University of Pennsylvania and I also interviewed with some other people doing neutrino physics like Barry Barish. I remember going down to Caltech and there was a lot of competition. You know, neutral currents, are there neutral currents, all this kind of stuff. There was a lot of competition in those days between people doing neutrino physics among the people doing neutrino physics at Fermilab. Rubbia-Barish, for example. So anyway, so I went to the University of Pennsylvania briefly. [laugh]
How long did you stay there?
I lived at Fermilab, even though I was employed by the University of Pennsylvania. And it was about a year. It was a very intense year, though. We were doing this experiment that had been partly setup and that climbed, Rubbia and Mann had developed at Fermilab, and we were doing experiments beyond that. And so, you know, as usual, I was involved in the hardware side and a little bit in the analysis side, but initially the hardware, because you know that's what first year postdocs do, mostly. And so, I dived into that and tried to understand that. And it was, there were a few interesting moments will Al Mann, shall we say? He fired me once. He rehired me the next day. Because I was, what's the right word? I was intense. And so one thing, the thing that he didn't like, was they had some complicated data acquisition system that in those days was like bins with modules and cables and all this stuff. And so I couldn't understand what somebody...the guy who'd come before me had done. I couldn't understand it at all. So I just took it all apart and put it all back together. And he said, “Holy crap, it's never going to come back together or work.” And so he was very unhappy. And so he indicated, “Well, you know, maybe you should seek employment elsewhere.” But then the next day he reconsidered and so in the end of course, I put it back together and it worked fine. And we got along pretty well.
Gil, what was the state of play with neutrino experimentation at that point?
Yeah so there were anomalies, so-called anomalies, and things that people didn't quite understand. And the whole picture that we have today, which is quite clear except for neutrino oscillations maybe, it just didn't exist. And so, people are sort of fumbling around, if I could call it that. Trying to figure out what is going on. And so that was the feeling that I got. And so you're basically poking around and trying to do experiments, and there were competing experiments, you know, Barish and company were upstream of the experiment that I was working on, and basically just doing neutrino scattering, analyzing the results and trying to understand how this fits into what was becoming the Standard Model. And so there was a lot of interest, particularly initially. And actually-- but even over the course of a year, it had waned, I would say, in the community because people realized that things are pretty standard. And also, guys like Rubbia of course had gone off and left this interesting field and were going off to p-bar-p activities at CERN, for example.
Did you ever have the opportunity to visit CERN?
So later, yeah, many times. But that's sort of after the SSC, when that was, yeah, so if you want to follow the chronology after.
That comes later.
We need to stop at Cornell and a few other places first.
[laugh] How did the opportunity at Cornell come available for you?
So, in those days, people would actually hire assistant professors with very little experience, which certainly applied to me. So, there were jobs like MIT, Cornell, other places.
Oh, so this was a faculty position at Cornell?
Yeah, faculty position. So, I, you know, I said, “Well, why not?” [laugh] So, I applied to a faculty position at MIT and Cornell and probably other places, but those are the two that I remember. And you know the MIT one they said no. Cornell in the end said yes after inviting me out, talking to me, and so on. And so I went from a postdoc for a year, into assistant professor at Cornell. It just took a year to do that after graduating.
What research projects did you get involved with at Cornell?
Oh, that was a lot of fun. It was incredible. So, what they'd done is they were in the process of creating an e+e- collider there, as well as building the major experiment, CLEO. And so, I just jumped into building CLEO. And eventually not just building but operating and doing physics analysis for that for about eight years. And that was an incredible experience. I also was teaching. I was an okay teacher, not the best I would say. But you know, so I was basically a faculty member over here on one part of the campus then you know after you teach, you walk a little bit to the other side of the campus where the accelerator was. And go to work. Come back at night, go to work. Work on the Saturday. Saturdays in those days were classes and all of the senior physicists would work on Saturdays. It was fantastic. There were a bunch of the oldest people who were running the place, many of them had worked during WWII, either on the Manhattan Project or other projects, and they had this like holy-- you got to work every day except Sunday, but you should really work Sunday too. [both laugh] And it was fantastic. It really resonated with me, because I like to work.
How far along was the CLEO detector by the time you joined?
It was just starting, really. And you know the design, the basic design had been proposed, but all of the construction was just starting when I got there, and so for example, I worked on the drift chamber. The tracking chamber. Which was a very interesting experience. And so, we started that from scratch. And one of my jobs there was there were thousands and thousands of holes in this aluminum plate, and aluminum plates between which the wires were strung. And so, one of my jobs was to shepherd getting all of these holes drilled and at a company in Rochester. Which I did. So I used to go up to Rochester and go into this company, and I'd device some gauges that I could see, well, you know, did they really put the holes in the right spot? And I then followed it through to construction, finishing, all of that, putting it in place, wiring it up, getting all the electronics going, taking data. Doing physics analysis. I was physics analysis coordinator for the group for a while. It was fun.
Do you know the backstory of why Cornell got the CLEO detector?
Not so much, really. I know that they were NSF-funded, in part. And, of course, in those days, in terms of these high energy physics, NSF would fund the three Cs, right? Cornell, Columbia, and Chicago. And the NSF wanted to remain, what's the right word? Credible. I don't know what the right word is. They wanted to have some role in high energy physics, and so Cornell was part of that role. At least, that's what I understand.
How much teaching responsibility did you have?
I had a full course load. In those days, there was not much relief.
Oh, you were a busy guy.
Oh yeah, I was really busy. And I had not done-- I had done some teaching as a graduate student, but not much. And they were kind to me at the beginning, to sort of ease me into teaching. I found teaching very challenging. But you know, you learn right? And anyway, this concept of the like, you know, you buy people out, you know, that didn't exist, right? And what are you talking about? [laugh] You do the teaching and if you can't get the work done, come back at night and come back on the weekends and get it done.
How did Cornell get involved in b physics?
Well, it was just the reality of the size of the storage ring. That's what they could do, and you know, the tunnel that they had, existing tunnel that they had, that's what they could do. And with the existing technology, or work any technology in fact, given the bend radius. So that's how they got started.
Who were some of Cornell's competitors at that time in b physics?
So it was competition from Germany, who was trying to do similar kinds of things.
At DESY, you mean?
DESY, yeah. And then of course later, you know, SLAC, and in Japan with Belel and so on. But that came later. So it was a very interesting time to discover the first b meson and so on. That was a lot of fun. I remember, I remember there was like a handful of credible events, and so it was a very interesting time.
Did you take on many graduate students when you were a professor at Cornell?
I was a junior professor, so you know, most of the students were taken on by the senior professors, full professors. But I wasn't very old right? So, I assisted the senior professors in mentoring the students. It was okay. I was all right. But it was interesting because they were only a few years younger than I was. We were all just working like crazy all the time.
Not that you had many places to compare it to, but was the Cornell physics department, was that a good place to be a junior professor? Was it a supportive environment? Collaborative?
Oh yeah. It was great. For me, it was incredible. I mean the department was supportive. They were very, they really understood the need to work hard, right? Because the accelerator is there. I think the other feature was the management of the particle physics side. Boyce McDaniel, you may not know that name much.
I know that name, sure.
He was an amazing guy. He was one of the most no-nonsense people, no-bullshit people that I ever, ever worked with.
Gil, was there a sense of a hierarchy between theory and experiment among the faculty at Cornell?
Yeah, you know, sure. You know, when you've got Hans Bethe and Ken Wilson. Ken Wilson was like, he was the most-- I've met a lot of Nobel prize winners. But he was like… whoa. He was thinking somewhere else where I don't exist, and you could tell--
You mean just his raw intellect? It would just radiate off of him?
Yeah. Yeah. It was like, you know, it was like talking to some alien person. I don't know. I don't know how to describe. But it wasn't like there was a big separation. All these people were accessible. And for example, I remember I was-- one of the things you do as a junior faculty is arrange seminars and sort of teaching things, and I asked Wilson. I went up to Wilson and said, “Hey, you know, could you sort of give us a pedestrian's view of what it is that you're doing?” And he said, “Okay, I'll do that.” And so, no transparencies in those days. He just got up on the blackboard and started from the beginning. Or the whiteboard. And just laid it all out. And it was amazing. So, there wasn't a lot of separation between these guys and the side-- there was a lot of mingling of the people.
Gil, was your sense that unlike a place like Harvard, that Cornell really supported its junior faculty and that the default was to move toward promotion?
Oh yeah. Absolutely. Absolutely. In fact, they were extremely encouraging. All of them like Daniel, Berkelman, Gittelman and Silverman. All of the “-men.” All the senior guys who'd been around forever. They were incredibly supportive. It was just-- it was great. There was no, you know, we're not testing this guy and see if he meets the criteria. We're trying to help him get tenure. Which I eventually did. But they were very, very supportive. It was a great working environment.
I'm trying to foreshadow to exactly how much risk you took on when you decided to jump into SSC with two feet.
It was a lot of risk, actually.
Yeah, yeah. I mean you were leaving a tenure job at that point.
That's right. And that's right, yeah.
So to set the stage, how active were you in sort of the high energy physics community? Were you involved in SSC planning going all the way back to '82?
Yeah. Well, I was involved on the experimental side way back from the, I would say, mid-80s.
Who were some of your key contacts in SSC planning from the beginning?
So, you know, we were-- some of this was at Cornell, and so Maury Tigner, who you surely know about.
Was very involved in the accelerator side, even before going to Berkeley. And there were a lot of workshops and so on, and I was really interested in this. I was always trying to, you know, work really hard on the stuff that I'm doing for Cornell, but I was always kind of interested in what could we do in the future? So, I got involved in these workshops for instrumentation. There were a lot of challenges, instrumentation challenges at the SSC. You know, you didn't know how to do things. And so there were many workshops and I got interested in that. And then I decided to just, let's put together a concept for an experiment. Draw it up. A cartoon. What's in it. So, I was one of the people who started to do that. And then I just got sucked into this. [laugh] You know, the work particularly on what are the experimental concepts and what are the instrumentation challenges and tried to-- I was one of the early leaders in trying to formulate and document and study what are the instrumentation challenges. What can't you do and what do you have to do? Which there are a lot of because of the intensity of the SSC.
Gil, what compelled you-- Did you go on leave initially? Or did you just fully resign your position?
Yes. No, I went on sabbatical leave. So, Maury-- so the thing is, Maury Tigner, and there's of course a huge story there that I'm sure you know, about forming an SSC central design group that was...eventually went to Berkeley. And he formed that group with a few people. Stan Wojcicki, Dave Jackson. Some others. And then he was trying to attract people to do work on the SSC, right? On sabbatical leave or in some cases hiring. But a lot of people on leave, on sabbatical. And so, I had one, I'd been there long enough to have such a leave coming up. And so, I did that. And with his urging-- And there was another feature, you know, I'd gotten married. My wife was trying to find a job, and I think couldn't find a job in Ithaca. Found a really nice job at Lawrence Livermore Lab [laugh] and so we moved and I was on sabbatical leave working for Tigner some, but also Stan Wojcicki, who--
So physically, in 1987, you were already in Berkeley?
Yeah. And so, we just moved and we had always-- We were trying to think ahead and said, “Well, you know, are we ever going to move back, you know?” My wife couldn't-- Ithaca is a very small town, right? In those days, finding positions that would be there were very challenging, and she had a really good job at Livermore. Anyway, we ended up buying a house, right? But anyway, I was on leave and working with the central design group. Some for Tigner on some accelerator-based problems, but mostly with Stan Wojcicki on trying to organize the experimental side. And in particular, what money, what DOE money would go where on detector R&D. Which everybody knew was important to figure out how to build these experiments.
Gil, of course the autopsy of the SSC is somewhat of a cottage industry. I'm curious from your perspective, what early warning signs did you see from the R&D angle that suggested maybe this thing was not viable long term?
Well, technically there were none. And the challenges in the SSC and the fact of its demise had nothing to do with the ability to technically do it. And I think, you know, the fact that the LHC has been an incredible success and the luminosity that they've achieved is remarkable. You know, it shows that the technical issues could all be overcome. It was really the management and financial issues that doomed the SSC. But in the early days of the Central Design Group, those didn't exist. The Central Design Group was-- you know, Cornell was a fantastic place to work. So was SLAC and so on. But the Central Design Group is the only group, large entity that I've worked with, where the sum of the parts was greater than each. it was some kind of synergy that Maury Tigner and Wojcicki and Jackson put together that just made more-- you know, the end product was more than the sum of the parts. And it was a fantastic--
Who were some of the key people you worked with during this period?
So it was Tigner, it mostly was Wojcicki, a little bit with Dave Jackson. But what I mostly did was eventually work with a committee of experts from around the country and around the world on detector R&D. And this committee had been convened to sort of guide the distribution of funding on detector R&D. And so Wojcicki was the real official lead, but I was the guy who was doing most of the actual work. Because Stan was very busy in the politics and the other things.
And what is the actual work? What does your day-to-day look like for this?
So early on, there were some problems that Tigner wanted to have fixed like what happens, what are the sort of seismic or ground distribution problems with this monstrous accelerator anyway. But so that was just like a problem. But then for the R&D, it was really studying and documenting what it is, what would you like to build and why can't you build it and what do you have to do to figure out how to build it? And most of this revolved around radiation damage or intensity from the luminosity. And so, I did with some other folks put together reports on radiation damage at the LHC, put together reports on what, by tracking system, by electronics, by calorimetry, by muon identification, what do you need to do to actually build an experiment at the SSC? And then there was a lot of work involved in-- we had an august committee of experts. Abe Seiden, Veljko Radica, you know, Brig Williams. Whole bunch of people whose names I'll eventually be able to remember. There was really a committee of complete experts on all of these different pieces of the experiment. It was the best committee that I've ever-- standing, long-term committee that I've ever been involved in because the DOE had fortunately, in these it's like remarkable today, there was like a lot of money. [laugh] And where do you put this money? And so that took up a lot of time to both have the committee meetings, preparations for these committee meetings, documents, prepare documents, figure out what it is, workshops. We tried to arrange workshops in each part of the experiment.
Gil, to what extent were you involved with discussions about what new physics would be discovered as a result of the SSC? Were people talking about the Higgs? Were people talking about supersymmetry?
Yeah, the Higgs, I was involved mostly with the Higgs because Ian Hinchliffe at LBL and you know Eichten, Hinchliffe, and Lane had written this epic, comprehensive picture of SSC physics. And I worked a little bit with Ian on, you know, how do you actually do this in particular areas? But most of my activities were more mundane in terms of instrumentation and trying to get the R&D off the ground, which we did, of how you solve these technical problems to allow experiments to be done at the SSC. It was very rewarding. All of the ideas, concepts that were originated in those days are now, or have been, or will be, implemented at the LHC. Pixel detectors, high speed silicon detectors, liquid argon calorimetry, you know, segmented scintillation calorimetry. Even silicon tungsten calorimetry, I think it's going to be implemented. And all of the electronics system development, ASIC development. Integrated circuit development that everybody realized was critical. It was amazing.
Gil, talking about finding the Higgs in ‘88-89, I wonder if you had ever thought back to not being in Burt Richter's group at SLAC and this time around before things went south, if you had picked the right horse.
Yeah, yeah, yeah. You know, the Higgs was, well, the difference was the Higgs was, there were actually predictions for the Higgs, which in those days were not anywhere near as crisp as they turned out to be. And so, I think there was a lot of feeling that the Higgs would be a much higher mass than it ended up being. [laugh] But what was clear in terms of the horse, the SSC would have been the pre-eminent accelerator in the world, right? That's a pretty easy horse to get on. Till it falls off a cliff.
And what were the circumstances of you being head of the research division at SSC?
That was a second choice. So when Texas was selected, and then there was a selection of different management, Roy Schwitters, you know, I could have gone back to Cornell. Cornell would have been happy to take me back.
And you were on leave the whole time? Or what was your status?
Yeah, I had to resign. Eventually I had to resign and so, you know, you can't be on leave forever. But they would have taken me back. But I decided, you know, go for it, basically. And so I became employed by the SSC laboratory and commuted to Texas from California every week. [laugh] And so Schwitters, he asked other people to be head of the research division. They all turned him down. And so I was there-- and so I became that. It was not a great fit, I would say, looking back at it.
Were things trending toward shopping for real estate near Waxahachie? Or Dallas?
I tried. I tried, you know, my wife tried to get a job there. Didn't work. And also, as things evolved, my-- let me say, my desire to work in that organization waned quickly. And you've surely read or talked to other people about these days. You know, the transition from a group that was very tightly well-organized, greater than the sum of its parts, which was a central design group, to the SSC laboratory, which was absolute chaos, just unbelievable chaos. Was even for a young, naive person—which I was—was pretty apparent. And so, it became pretty clear that I would like to bail and not work there. And part of what I did in accepting things was, you know, I'd spent years working on this project. I wanted to make it work, right? And so that was part of the motivation for going to Texas, was to make it work. But it was a very, very challenging working environment.
And so then your subsequent involvement with the solenoidal detector, this is a pivot away? This is your exit strategy?
Yeah so basically what happened was, you know, I worked for the SSC lab, I tried to hire people because there was nothing there, right, to establish a division that would support experiments, and it was clear I was not the right kind of person both from my perspective and also the lab's perspective, and so eventually as you know, they hired Fred Gilman. He was not the right person either. [laugh] But he was certainly older and more experienced than I was in some respects. And so, then I had to find a job, and fortunately Pierre Oddone, we'd interviewed, and others in Berkeley. You know, I'd associated with him and George Trilling and other people in Berkeley, and so they sort of knew of me and when I became jobless effectively-- I didn't have a job for a brief time, they hired me in 1990. Pierre did. And so, then the question is, you know, what do I do? I can't work on the SSC. The laboratory infrastructure from Berkeley, it doesn't make any sense. But you could work on the experiments, and of course I knew all about the experiments and had actually drawn the picture for what the solenoidal detector collaboration should look like.
And why would this be at Berkeley and not in Texas, if it's oriented toward the SSC?
Yeah, so it was a collaboration. George Trilling was the spokesperson. And there was nothing in Texas, right? There weren't in terms of people. All the people were in existing labs, universities, and around the world, and so it was pretty easy to design an experiment for Texas initially without being in Texas. And so George Trilling was the spokesperson, and I became the project manager basically for SDC. And so that's what happened initially when I came to Berkeley.
What was the nature of that research? What was the solenoidal detector all about?
So, it was intended to be the first general-purpose experiment at the SSC. So in those days, there had been great success from the collider detector facility, CDF at Fermilab. And which was in a similar spirit. A predecessor, if you like. And so, the SDC was intended to be that, with a big collaboration, do all the possible physics with a general purpose detector, and do it first. So that was the, you know-- it would do anything. Higgs physics, supersymmetry, you know, new bosons, anything, right? So, it was supposed to do all of that kind of physics. And to be the flagship experiment at the SSC.
What were some things that came out of this research?
Yeah, so part of it was a continuation of the instrumentation research that was initiated during the CDG days. So that research had advanced quite a lot in terms of not just really basic R&D, but design of subsystems. Silicon subsystems, tracking subsystems, and different types, calorimeters. So basically, we took these pieces and put them together in SDC. So there was silicon tracking, a big amount of silicon tracking, which was just like a revolution in those days. Gas chamber tracking, solenoidal magnet, segmented scintillation calorimetry, and then using acres of detectors for muon detection outside of iron. Pretty conventional. But even by those standards-- but the difficulty was the number of elements in the radiation damage were tremendous, but they'd all been studied by these instrumentation groups. So there were proposed solutions for every one of these pieces. So we put them together at SDC. And I helped put them together, basically.
And Gil, to what extent was SDC decoupled from the cancellation of SSC? In other words, could that research have gone on even when Waxahachie was kaput?
It did. Yeah, it did, so in the sense that what happened was, all of these concepts apply to any high luminosity hadron collider. And so they were all later applied at the LHC, either in ATLAS or CMS.
And what's your employment status at this point? What was the name on your paycheck?
So I was hired as a senior scientist in 1990. And I became-- I worked for George Trilling. When the SSC was killed, he decided to retire. And he retired and I became the head of the group that he had formed. Which was the most powerful group in the country in terms of both, let me say, scientific capability and technical capability. So essentially all of that went—after a lot of tears—went from the SDC at the SSC to ATLAS at the LHC. And there was a process, you know, are we doing ATLAS? Are we doing CMS? As you know. There was a group of people including George Trilling that sort of negotiated with CERN about US participation for the LHC. And so the Berkeley group transitioned over a period of a year plus from working on SDC to working on ATLAS.
And when did you get involved first with ATLAS?
Oh, right at the beginning because once George retired and I became group leader—it was my job to make everybody in the group viable in terms of working on ATLAS, which was pretty easy actually because they're all really smart people. So, we just made that transition. It was very hard because people were deeply invested in the SSC and SDC.
It was really-- But you know, you've got to look to the future, and so that transition was made, and we began to work on ATLAS. There were some associations of some of the people who'd done postdocs at CERN with the head of the ATLAS group, Peter Jenni and others. And so, there was a natural connection there. Not for me, because I had never worked at CERN, but for a lot of the people that were in the group.
Did you have much interaction with Trilling before he retired?
Oh yeah, yeah. George was an amazing man. He's certainly, of all the people that I worked with, he had the most impact on my thinking.
In what way?
He, first of all he was just an amazingly kind, stable, sensible person. Somebody used to joke he had the best legal mind in Berkeley. But he was, his methodology of studying things and writing, particularly writing, really had a big impact on me. It's hard to describe, actually, but he was very thoughtful, very clear. You know, some people were very smart, but it's really difficult to understand what it is that they're saying, you know?
Not because they're smart, it's just that they don't communicate clearly. George was an amazingly clear communicator. And in writing in particular he was a stickler for every word counts. In those days I would work for him, and I did a lot of stuff with him, so I would write documents, send them to him for comments. They'd come back and they'd look like they were just bleeding. [laugh] And so I slowly learned how to write clearly and concisely. And it's carried over forever. But he was a mentor in the sense of, how do you deal with people? He had the best group in the country working on this stuff, and so he transferred some of that to me, and I tried to continue it for 14 years. [laugh]
Gil, what was your initial work for ATLAS, and how did that contribute to the overall mission of ATLAS?
Yeah. So initially, for me it was a challenge, for a couple of reasons. One is I had never worked at CERN and the European way of doing things. And I worked a lot in the American way of doing things, which certainly in those days and today too, although less so now, were quite different. So I was challenged. The other feature was that we had to decide what it is we as a group at Berkeley were going to do, and it was pretty clear because of the history of the instrumentation and R&D that had been done for the SSC. So we jumped into silicon detectors and pixel-- silicon pixel detectors, which in ATLAS are two different subsystems. And did both. As well as some of the physics analysis. The initial proposals, one of the people from Berkeley was the guy who presented the physicist case for ATLAS to the world, for example. Kevin Einsweiler. So we jumped into-- and I particularly jumped into, parts of the silicon tracking and pixel tracking. Particularly the pixel tracking. Which people had done a lot of work on but were still very, very early in R&D. And so, we did a lot of that basic R&D, both on electronics, detectors, and where I ended up because of my interests mostly was in trying to figure out how to build the-- how do you hold all of these detectors up with absolutely no material? [laugh] And so we invented—we established, not invented. We established at Berkeley a capability to make carbon composite structures. Which exist today and it's being used in the ATLAS upgrades. And so I helped do that. And because we needed some way to actually hold all this great stuff together and cool it off and things like that. So we established that capability, and we made parts and shipped them to CERN and then installed them in the detector, in ATLAS.
Gil, to the extent that you saw these developments in national terms, I wonder how much you thought about how after the SSC the United States essentially ceded leadership to CERN in high energy physics?
And that this was work was a way for American ingenuity, American leadership, to continue to contribute?
Yeah, so the situation was that because of this development, the SSC experimental development was ahead of where CERN was. A lot more resources had been put into it, and it was a lot closer to reality than what CERN had. And so all of the groups—the people, the thinking, the techniques that had been developed through this instrumentation R&D phase and then the SDC phase and other experiments that were proposed at the SSC. They all were directly transferrable into the LHC. And so the feature was that they were advanced. More advanced than the concepts that the European side had. So there was some friction, and in the end, you know, I think it really benefitted the LHC program to get all of this technical advancement that the US had primarily led into those experiments. And of course, they worked extremely well in the end.
Gil, to what extent was there concern that LHC was not operating at the energy levels envisioned by the SSC, and that that-- GILCHRIESE: A lot.
--might hamstring new physics?
Yeah, there was a lot of initial concern because you know, people did not believe that either you couldn't obtain the luminosity, and if you did obtain it, that the experiments would still function. [laugh] But to go back a little bit on that front, somewhat amusing thing. There were in the SSC days, there were these Snowmass workshops every two years, which were actually at Snowmass instead of some other godforsaken place, and these attracted the whole community. And so, I remember very distinctly in 1984 there were presentations on how to do experiments at high luminosity hadron colliders that, you know, a luminosity of 10^33, which is what the SSC goal was. And Leon Lederman and others, who were very smart people—Leon was an amazing man—they simply didn't believe this was possible. They were too old. It was a really bad thing to say, but they were just too old. And I remember he was sitting in front of me when someone was presenting an idea that he didn't believe would work, and he wrote in his-- he took notes-- he wrote in his thing, you know, “Crap.” or “Won't work.” or I don't remember the exact words. Because I was sitting right behind and watching him write this stuff down. Anyway, the point is that the SSC was 10^33, LHC was 10^34. People didn't believe in the 10^34. And furthermore, I didn't believe that you could do sustained experiments at that. And of course, they were wrong. And so, but it took a while. What was the alternative? Well, the alternative was to give up, but nobody's going to give up. And so, I think really put their efforts behind trying to make things that would work at that really high luminosity. And now today of course, eh, you know, piece of cake. 10^34. 10^33? What are you talking about? That's so easy. But it wasn't in the 80s, early 90s. It was viewed by many smart people as being impossible.
What were some of the administrative responsibilities heading the ATLAS group from LBL?
Yeah, so, part of it was just sustain people who had permanent jobs at LBL, but also recruit postdocs and so on. It was challenging to recruit postdocs, because a postdoc coming in could only work on instrumentation, right? It took forever from 1993 to when the LHC turned on. And so what we did is, there were still activities working on the CDF at Fermilab, so people would do instrumentation then do data analysis on CDF. And so have the full range of postdoc kind of things, graduate student kind of things. And so it was trying to get that. The other feature was-- it was actually to organize ATLAS into projects that delivered stuff. Lot of engineers, technicians. We had… I forget. At one point I was nominally organizing something like 40 or 50 people. You know, when we were full-scale building. So, it was a big range of people from technicians doing thousands of the same thing every day to these senior scientists who were driving things or wanting to drive things. It worked really well, and why did it work well? Well, really smart people all headed toward the same goal. It didn't require a lot of management, shall we say.
Gil, as you emphasized earlier, it was not the technical challenges of the SSC. It was management, bureaucracy, and budgeting. This of course raises the question: given the complexity of the collaboration at CERN, I mean, how many countries as a joint European shared project, with the United States involved? It would seem that the administrative, the budgetary challenges at CERN, would have dwarfed what the SSC had to deal with. So, what was the difference? How did the LHC succeed?
Yeah, yeah, that's a really good question.
I'm thinking now, just if you compare the vaccine rollout in the United States versus the EU, right?
[laugh] Yeah. Yeah, the problem is, it's different, I would say. Different. So, there was a lot of apprehension about what you say. Because we had gone from-- the SDC had actually gone through formal DOE reviews. It was very organized, right? It was very structured. The costs were well-known. Now you go to the LHC, and it's got all these countries and they have to provide money or stuff and you know, there's no real cost estimate. [laugh] It looked like quasi-organized chaos to a lot of us. But what eventually-- and it took forever. It took years for me to appreciate this, is that it's a very strong way of working when you have many, many countries who all feel responsible and don't want to be the one that lets down the other countries [laugh] and CERN does an incredible job of managing all of these different countries and funding sources, right? And so it took me a long time, many years in fact, to appreciate that the so-called European way of doing things, you know... There's independence in these countries, but you're all working together. It worked. And it really worked well. I mean the LHC, the LHC experiments, are, they're amazing. And so, in the end it worked really well, and in fact that model is superior to the US model right now.
From your vantage point, where was the redundancy if at all, and where was the synergy, between ATLAS and CMS?
Yeah, that's an interesting question. So, I think there clearly was a lot of overlap in capabilities. Extreme overlap. Which I think turned out to be very useful. So in the sense that people were trying to do exactly the same kind of physics analysis. Also fighting some of the very similar technical challenges. And so, there was, in the early days, there was a lot of competition, I would say. Today, for example, I think there's much less competition. In fact, some of the technical developments are shared between the two experiments now. And that wasn't the case when we did it in the 90s or 2000s, early 2000s. But I think the competition is a really powerful stimulus to getting work done. It really works.
Even internal competition.
Yeah, it really, really works. it's great. You have to balance that against being absurd and not sharing information, for example.
Would you say that that accelerated the discovery of the Higgs?
Oh absolutely, yeah. I would say there was just-- it was competition at the technical level and exchange of information, and then once you have data, there's just, you know, “we don't want those CMS guys to do this first!” And of course, CERN handled this pretty well. They wanted things to come out together right. And given the importance of the discovery and let me say early evidence, which was not overwhelming. It wasn't the J/psi, right? So having both experiments come out at the same time was very important.
Gil, looking at the chronology when you stepped down as the head of the ATLAS group and when the LHC construction ended, when it was completed in 2008, was that coincidental or not?
No. So, I got tired, frankly, of both the head of the group and going to CERN.
I would have thought, though, that once the LHC is operational, that's when the fun begins.
Yeah, well, it's true, except my inclination is more on the, you know, early phases of things, shall we say?
Build it and let others analyze it.
That's pretty much it, yeah. You know, people, wiser people than I, can do both. But for me--
To what extent did the ATLAS group change under your successor?
I would say not too much. The gentleman Ian Hinchliffe, who took over was a really smart guy. He's a theorist, so he had much less connection with the technical stuff but because all the technical stuff had been done, you know, that was a good phase transition. It was analysis and for analysis, he was amazing. He partly wrote the bible on how to do [laugh] analysis at a hadron collider.
So, it was actually probably pretty good timing that your successor--
It was pretty good timing, yeah. Right. Right.
What did you do next?
So, I wanted to do some-- I didn't want to go anywhere. I didn't want to travel. I was really tired.
You had logged enough flight miles at that point.
Yeah, well, I got some back later. But anyway. So, I decided I really needed a complete change of, what's the right word? Direction. So, there was-- So I looked around and there were two possibilities. One was to work on what's generally called cosmology, you know? Experiments related to looking at the sky. And the other was deep underground experiments. Dark matter in particular. And so for various reasons, mostly practical reasons, I chose the latter. There was a gentleman at LBL, Kevin Lesko, who with others was proposing this deep underground science and engineering laboratory in South Dakota, and that looked like a lot of fun, you know? It's completely different than what I'd done. And he was again trying to organize a group to design this and cost it out and get it approved. And it was a group that was based near, not on, the campus specifically, but in UC Berkeley-owned space that was right next to campus. And so again, it was one of these things where it was like forming an initial idea, getting people together, what does it look like? And so anyway, I sort of volunteered, and then he asked me to sort of take over the experimental coordination side of this, which was sort of right up my alley, right? Even though I didn't know shit about [laugh] deep underground experiments. But I learned. So again, it was similar to what I'd done for the CDG, in fact. It was talk with different groups, get conceptual designs for different kinds of experiments so that we could do a cost estimate and write proposals to the NSF, in this case, to build this laboratory. Go to South Dakota, understand what's going on there. So, it was a lot of fun, and also the really great food, because you're right next to the Berkeley campus, and for lunch you can go out and get whatever you want. So again, we did this. Made a proposal. In the end it's, as you know, the National Science Board decided not to do this. That it wasn't appropriate for the NSF. But it was a lot of fun, actually.
Gil, the search for dark matter is, it's great because it's very much an all hands on deck kind of proposition across physics. That you have people from every-which subfield looking for dark matter. What was your sense--
No, David. Yeah, no.
Yeah nowadays. But what was your sense in the relatively early days? What was the deep underground science collaboration? What was its contribution going to be? Uniquely for the search to dark matter?
Yeah, so in those days, there were small-scale dark matter experiments, but also in other deep sites to shield them, as you know, from cosmic rays. And it was clear, which may be wrong, but it was clear then that you need to scale up these experiments by a lot. You know, factors of 10, 100. And so that's an interesting proposition. How do you do that? What challenges do you have? How do you get it done? How do you get it approved by some funding agency? So that's, you know, the concentration on scaling up, for example, liquid xenon experiments to look for WIMPs was, you know, everybody thought that was a great idea. And today, because of the history and the lack of discovery, right? It's a much more shotgun approach, but in those days, you know, it was, “Okay, let's make as big as possible experiment to look for WIMP signatures. And let's do that underground.” Liquid xenon was pretty clearly, and still is, for the class of WIMPs that are, you know, GEV-ish and above, was the preferred approach because it could scale and also had all of the low background properties. So the job was-- and of course this happened in Europe. With the xenon collaboration. Which I was not part of, but people I worked with were, and apparently it was rather or maybe is a rather fractious collaboration. But you know, they're very successful. Anyway, it was very clear I think to the community in the US and to the DOE and the NSF that they should scale up from, you know, from ten kilogram to hundreds of kilograms or to tons. And that's basically what we did.
How did this lead to the Sanford work that you did?
Yeah so, the deep underground science and engineering lab did a nation-wide search for sites, for such a lab, and basically asked people to bid, right? And there were sites considered in California, Colorado, in addition to the former home state line in South Dakota. Home state won this competition and why did it win? Well, South Dakota and a gentleman there, T. Denny Sanford, they put their money where their mouth was, and they really put a lot of money behind this idea. $125+ million or something. So that money and the initiation that they provided basically created this capability to do underground science in South Dakota. And because Mr. Sanford provided 70 initially or later more, it got named Sanford Lab because of that. It started, and so it started from nothing, which is as you probably can tell, is appealing to me. And you know, so establishing that and then when the NSF bailed, the DOE agreed to take this over, and Kevin Lesko was the chief and I was the deputy, for the DOE funding of getting a laboratory continued and building it up.
Gil, just to zoom out a little bit on that point, so the story of DOE getting into the business of supporting astrophysics and cosmology, you know if we take it back to Ray Orbach and his support for Saul Perlmutter, was your sense that at this point, LBNL's overall research mission had transferred primarily from high energy physics to astrophysics and cosmology? Or not necessarily?
No, no, it was a very gradual transition, I would say.
Was the dark matter research still on the early part of this transition?
It was later.
So later, so-- Sometimes, and even though DOE is a mission-oriented agency, it's really where do the physicists’ feet want to go, right? And so, some of the physicists at LBL—Gerson Goldhaber for example, who had done particle, traditional particle physics, transitioned to cosmology and frankly, the unexpected discovery of dark energy just like it was revolutionized, what the field has done and in particular what LBL has done. You know, without that discovery, we'd still be just doing accelerator-based mostly experiments I would say. So, it happened just because people wanted to go off in some different direction. And I suspect the DOE went along with that because they were smart people or maybe they went along with that because they didn't know they were going along with that? I don't know. So [laugh] and then of course once there was some big success, like the discovery of dark energy, or mapping the CMB for example, then it became, you know, that's basic science that office of high energy physics should support. And so LBL has made, and other places have made, but LBL in particular has made this transition where cosmology, astrophysics, is equal if not larger in size to accelerator-based physics. And dark matter is a part of that. Because it doesn't-- some of it needs accelerators, but not most of it. And dark matter started off as a bunch of crazy guys who want to look for dark matter with liquid xenon. or something like that, or crystals, you know? Bernard Sadoulet at UCB was one of the founding fathers and a lot of his postdocs or students went off and became the leads for other dark matter experiments.
You were dual-hatted at Sanford and for the large underground xenon project. In what ways were these separate and in what ways were they interconnected?
Yeah so they were quite interconnected, but the role for Sanford was really a very administrative role, actually. There was a person in South Dakota who runs the lab. It was originally a gentleman named Ron Wheeler, and then it became a gentleman named Mike Headley. They are both very, very accomplished people. They really knew what they were doing. And so they, you know-- our role was to get them money. [laugh] And not to worry about the day-to-day activities at the lab because we were based in Berkeley, and sure, went to South Dakota a lot, but we weren't actually running it. So, our function was more administrative and it was-- so that doesn't take up all your time by a lot, so there was plenty of time to work on the actual experiment that would end up there. In that case, the initial one was locked. So, it was quite a different hat. You put on an administrative hat, okay, how am I going to get the money to there? Is your HR practice okay? And all this kind of stuff. And then you put on another hat, and say, all right, how are you going to [laugh] purify this xenon? You know, so it was related, but it was very different a set of activities.
Between Sanford and XENON and LZ, what was most enjoyable for you scientifically?
Yeah that's a good question. So scientifically, you know, I had never been involved in a dark matter experiment at all. It was completely different from what I'd done. And so, what was most enjoyable for me in that was essentially to learn how it should be done. There's an incredible amount of grungy nuclear physics in all these backgrounds that screw up the dark matter signal. But the most interesting thing for me wasn't so much the scientific result, which was just zero, right? That was the result. It was getting there. It was the journey. It was getting there. How do you do this? And I became project director for the successor to LUX, which was a very pretty obvious thing. The project director was really more like a project manager. And you know, formal DOE project, which I had learned how to do in the ATLAS days, and SDC days. So, I knew how to do all of it. What's the right-- DOE wrangling. And so, it was a pretty obvious choice.
What was the most tantalizing moment, if any, that you were onto something with dark matter, from any of these collaborations? Given today how, you know, difficult it still seems.
Yeah. Unfortunately, we never had a case where some postdoc comes and says, "Hey, I got a signal." You know, we've never had that.
Is that because it's possible dark matter doesn't have a signal to yield?
It's possible, yeah. So you know, it's clear since the days of initiating this at LBL, the thinking has changed. The WIMP signatures that seemed so credible, you know, similar, I would say, but not quite. Oh yeah, the Higgs must exist, right? Not true anymore, and so you know, you're really sort of stuck. There's this momentum which has been realized both at the XENON project to do ten-ish ton scale. Although XENON’s a little smaller than LZ, I've got to say that. If nothing is found by those experiments, then we are really still in the dark, and pardon the expression, and really are scrambling. People are already scrambling, but it'll even be more. So there's no—unlike the Higgs where there was a range of predictions and even supersymmetry, there was a guiding paradigm, a lot of simulations by really smart theorists that said this must exist. Here there's just nothing. You're lost. [laugh] The theoretical guidance is so diverse that it's like having none.
So Gil, here's where I'll ask you to put on your speculator's hat, right? Since we're not anywhere in particular in terms of the theoretical guidance, if you had your hunch, based on what you know, based on how you've approached this problem, what would you guess dark matter is?
Oh man I have no freaking idea. I really don't.
What about the oft-repeated metaphor, you know, you're looking for keys under the streetlamps and you're not looking where it's not light?
Yeah, that's right.
I mean, does that resonate with you?
Yeah, it does. But you've got to have some, how can I say? There's got to be some technically realizable way to get wherever you want to go, and it's clear people now know how to build, you know, really big liquid xenon or liquid argon experiments. Not that they're not challenging, it's just you know, you understand the challenges and maybe you understand how it would go. What you don't really know how to do very well is, okay, maybe it's MEV scale. Holy crap, how do you do that? And so people are really studying this now, and I think there's been a diversion—an explosion of new ideas. If I were a lot younger and not about to retire, the question is, where would I put myself? My money, so to speak? And I don't know.
Well, given all of your experience in detectors, is it possible that all of physics is just building the wrong kind of detector? I mean, the wrong kind of detector is not going to find what you're looking for.
Yeah, that's right. And the problem is, you know, you've got to detect it. Right? You've got to see it in something, and so the question is, what technique? Well, you could say dark matter is undetectable. Well, great guys. That doesn't exactly give me an experimental path [laugh] to finding it. So you have to, basically, it's a matter of—and people are doing this, right? —covering, assume it's a particle, and you're covering the entire mass scale that you can of what that particle or particles might be. That's what people are now doing. And axions, it's an enormous range of particle masses. It's just incredible. I mean it makes the Higgs look like-- [laugh] so remember the Higgs was between 100 Gev and a TEV or something. This one is orders and orders of magnitude worse. So, you now, people are going to devise techniques to explore these regions as best they can, but there's no real theoretical guidance as far as I can tell about which is better.
Gil, just to bring our conversation up to the present, your work on CMB-S4. What is that all about? What have you been doing with CMB?
Yeah, so I'm about to retire. In fact, I was supposed to retire last year, but the pandemic got in the way. You know, it's really true. You know, it would have been terrible to retire and just be utterly bored. Stuck at home. So I agreed, you know, that I gave up the operational responsibilities for LZ to a younger person who had been on board for a number of years, and had sort of been hired to do this, take over. And is doing a great job. So, what am I going to do? Well, I worked a little bit on, as I said, getting the lab back to work with COVID controls. I did that for Mike Witherell for a few months. Sort of got it to a place where people could take over. And then Berkeley Lab last August, the DOE said, “Well, you're the lead laboratory for this cosmic microwave background stage four experiment.” Which we did not expect to be happening. [laugh] There was a competition among SLAC and LBL and Argonne, a little bit of Argonne, Fermilab a little. And we were sure that we would lose this competition, but we didn't. We won. And so now you have to figure out how to get this project off the ground. Some work had been done, but you have to turn it into a DOE project. And so that's what I've mostly been doing over the last year, is trying to help get this thing lined up as a viable DOE project. The science behind this is really interesting. Looking at potential signatures of inflation, which is basically what it's trying to do. it's pretty interesting. Pretty hard to grasp in some sense. Dark matter, well it's sort of like accelerator physics because there's particles bouncing around here, right? But imprinting inflation on gravitational waves is, I'm still struggling to get that in my head, so. But anyway, turning a thing into a DOE project is something I sort of have some experience with and so I've been trying to help them.
Gil, what was it like receiving the Lifetime Achievement Award from the Lab in the middle of a pandemic? Did you give a nice address over Zoom?
I don't know about nice, but I gave a short address, yeah. Yeah I was surprised to receive this award.
How did you take that opportunity to reflect on your career?
Yeah, that's a good question. So, you know, I'm extremely fortunate in the early parts of my career in Berkeley, as I've mentioned, that the mentorship—particularly of George Trilling—and the ability to work with highly-motivated, incredibly smart people. That's really good. That really is, you know, my skill at Berkeley has been to, what can I say? Get all these smart people going in the same direction most of the time. That's really one of my skills. And so that's been quite rewarding, is to see things happen and see things achieved. And the Higgs discovery. Establishing Sanford Lab as a viable entity after, you know, being rejected by the government, so to speak, is kind of important. It'll live for decades and decades and decades. And we'll see about dark matter. Maybe we'll still find something. I don't know. It's not impossible.
Gil, for the last part of our talk, I want to ask a few broadly retrospective questions and then we'll end looking to the future. So as a detector guy, this conversation has been sort of been delightfully aloof from technology and the development of technology over the course of your career. So I wonder if you can reflect on, you know, the amazing growth in computational power, the ability of, you know, advances in lensing, Moore's Law in detectors and things like that? What have been some of the real highlights in technological advances that stick out in your memory as, these are advances that really moved the science forward in a way that it wouldn't have otherwise?
Yeah, that's a really good question. So, I think the one that sticks out in my mind is more in the hardware side. It's the development of integrated circuitry for particle physics. My colleagues had put together a beautiful picture of, you know, these ASICs applications, specific integrated circuits from you know 30 years ago. [laugh] ‘Til now. 35 years ago, ‘til now. And the ability to utilize that kind of, you know, commercial capability, which has evolved, it continues to evolve. And the scale of that from many microns, feature size, to you know, nanometer feature size has allowed people to put more functionality into, you know, per square centimeter into these integrated circuits and make them cheaply, so that they could do all kinds of things. And so, these are the basis of all of the LHC silicon tracking experiments, as well as the detectors. But it's really this incredibly rapid evolution of integrated circuits that has allowed these things to happen both for that and for high-speed data transmission, for example, and fiber transmission, and all of the kind of stuff that we now take for granted. So, seeing that happen has been pretty remarkable in terms of technological advancement. The other aspect you've mentioned, computing, you know, the thing that I've seen over my life is I've gone literally from, you know, punch cards or paper tape [laugh] to where we are today. And it's really interesting. The basic concepts are identical. It's just the magnitude that's really changed, and the ability of networking through the internet is in my lifetime has completely changed how the field works, right? Like today, like Zooming, right? And with incredibly impeccable video clarity. So that, you know, that's changed how things work, but the fundamentals of the computing—you know, you program something and it does something—are still the same. And I think the place where it's way outside my experience but where it's really going to take off is in artificial intelligence, where you don't program something, you program something that figures it out, what it's supposed to do, right? That's basically what it is. Some of that's come into the field, but not very much yet. I think that will become a field unto itself in many, many areas. Not just particle physics, of course.
To the extent that we might be trapped in our own minds, and that's a blockage to understanding dark matter, maybe AI will help.
Yeah maybe. What we really need in my opinion is a really smart theorist. [laugh] We need Mr. Higgs again, so that's what dark matter-- I mean, that's what we really need a direction from some theoretically well-inclined thing, and of course there had been. The WIMPs in particular, axions in particular. But so far it hasn't worked. So, we'll see.
Gil, advances in physics always depend on the interplay between theory and experimentation, so however broadly you want to divide up the increments in your career: every five years, ten years, first half of your career, second half of your career-- roughly speaking, when since you were a graduate student to now, when has theory led experiment, and when has experiment led theory?
Oh man that's a toughie. So in my-- since I was a graduate student, you know, when I was a graduate student, I would say you know, the quarks and gluons, the revolution or evolution was just being taken for granted. And clearly what happened in the 70s, the charm quark discovery basically, in the validation of the b quark then the top quark, you know, and the validation of all that, which was theoretically motivated, you know, was an enormous triumph and it was capped by the Higgs, which is—since it's named after a theorist—it's obviously the theory was ahead of the experiment. So, you know, this is an evolution that's where the experiments have sort of caught up with the theoretical, in my opinion, the theoretical directions that people have postulated. Where experiments have, you know, are dark matter in cosmology, is one area where I think experiments are-- you know, you can argue that because dark matter has not been found that it's not leading, well it is right? It is. Because people are pushing the technological limits and so the experiments, I would say are way ahead of the theorists in dark matter, and dark matter theorists, they're all over the place. They're really not very coherent. And to the extent I understand cosmology, you know, dark energy was clearly [laugh] experiment-driven, right? Nobody had a, you know, show me a theorist who predicted that. And so other aspects, I think, of cosmology are the sort of Standard Model of cosmology now is pretty good, right? And the real next thing is what happens in the very early, very, very early parts of the universe? I think that's a place where experiment at the moment is going to be ahead of theory. In terms of CMB for example. But as you can probably tell, I'm not the right person to give you a grand picture of the field. I'm more of a, what's the right word? A worker who gets things done.
Your perspective is important too.
Gil, last question. Looking to the future, to transpose your looking back, if you had to do it all over again, what would you do? And to think about that in terms of the influence as a mentee that George Trilling had on you. So for young people in the field, people that are pursuing the kinds of physics that you've been involved in, right? As a mentor, as somebody who can perhaps use your powers of extrapolation, to try to figure out where things are headed, what advice do you give younger people in the field in terms of the most interesting things to work on, the places where there's the most room for fundamental discovery? Where Berkeley Lab specifically might be a key player in these things?
Yeah. So it's, you know-- it's going to sound like old people, right? I would say two things. One is, you know, it's very difficult for most young people to have the kind of physics overview that older folks have. Like what's important, right?
You mean because there's just so much more stuff than there was 50 years ago?
Yeah, more stuff. But it's just, you know, if you were to say, “Well, I can do anything I want,” right? What would I do? And so, you know, the question is, what is the area where there's the most, if you were a student, you want something where the field is moving quickly, and it's moving to a place that will change where you go in the future. And people don't always believe this in my opinion, it should be hard. You should at least technically have to struggle to get where you want to go, because then you'll learn something technically as well as scientifically, so to speak. Today I would say that it's pretty clear that accelerator-based physics at the moment is reaching an end in the near future.
You mean absent an ILC or some other grand, new project?
Well, maybe even with. Yeah, you know, the rationale to study Higgs properties at the level of a percent, right? Which is pretty much what they're talking about. Yeah, it's not quite the same as discovering the Higgs. So, I think people-- if I were advising graduate students today, I would advise them to look, you know, dark matter is clearly an area where a discovery could be around the corner. The one where it's clear but you don't quite know how to do it, the one place where you do know how to do things, where fundamental information could exist, is in cosmology. You know, really studying both what amounts to the spatial distribution of matter in the universe, right? That's what people are doing. Whether it's dark or not. As well as very early universe through CMB or other methods, is, you know, I think that's a place where you know how to do it and there's a potential for really discovering things that would change your whole picture of the universe. So that's partly why I decided to, you know, in my waning moment [laugh] yeah, maybe I should just try something new again. And so, try something new that might—long after I leave it—might actually lead to something quite revolutionary. I don't know, did that answer your question?
Indeed it has, and I appreciate your straight-shooting style in answering it.
Gil, it's been a lot of fun interviewing you. I'm so glad we were able to do this. Thank you so much.
You do an excellent job. You're really, really good at this.
Oh, why thank you.