Gerassimos Petratos

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ORAL HISTORIES
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Interviewed by
Catherine Westfall and L. S. Cardman
Interview date
Location
Unknown
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Interview of Gerassimos Petratos by Catherine Westfall and L. S. Cardman on 2014 December 10,Niels Bohr Library & Archives, American Institute of Physics,College Park, MD USA,www.aip.org/history-programs/niels-bohr-library/oral-histories/42903

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Gerassimos Petratos joined the Hall A collaboration at the Thomas Jefferson Accelerator Facility in 1989. This interview explains his work with the collaboration, which included coordinating the organization of the collaboration, overseeing the development of Hall A detectors, and then scheduling experiments and helping with commissioning.

Transcript

Westfall:

Okay. I’ve got the tape recorder on, and I will say for the tape recorder that this is Catherine Westfall. It is the 10th of December 2014. Larry just walked in. I’m with Larry Cardman. Why don’t you, just to make sure that I don't screw it up, why don’t you spell your name for the transcriptionist?

Petratos:

Yes. My name is Gerassimos Petratos, but I go also by the nickname of Makis.

Cardman:

So philosophically, you know Catherine wrote the history you’ve probably seen of the founding of CEBAF, and she’s now coming back to work for us. First, she did a story about the CHL and its construction, but what we’re working on now is a magnum opus about the evolution of the science case and the planning for the experiments and the startup of the program. Eventually it will also cover the execution of the program, you know, what we did through 6 GeV. If life continues happily, she’ll then do one on the 12 GeV project and eventually one on its science, too.

The particular interest in talking with you has to do with getting the Hall A story down straight. You know, in the very early days, I was involved in a rather focused way with Hall C, and so I know a lot about how that collaboration formed and how the equipment got built and all of the players and so on and so forth. My knowledge of Hall A at anything other than the “Ah, that’s what else is happening at the lab level” really doesn't start until just before the commissioning when I got tapped to be temporary Hall A Leader while we were looking for a replacement, which was Kees de Jager. It would be interesting and valuable to get your story, your recollections —

Petratos:

Larry, we got interrupted. I missed the last sentence, what you said there.

Cardman:

It would be useful to get your recollections on how the Hall A collaboration formed and how it came together and worked and developed the plan for who was going to do what of the experimental equipment and exactly what equipment you wanted to build, and then how it all came together with the commissioning and the start of experiments in Hall A. I know you were one of the people who played a serious role in all of that in the early days.

If you ask me, it sort of began at some level with (e,e’p) being one of the core motivations for building the laboratory in the first place, and few-body experiments being another key motivation. There’s this famous quote I have in the back of my head from Erich Vogt that the nuclear physics community in the United States is a little bit like the political spectrum where on the far right there are these electromagnetic physicists who have an interaction they understand and few-body nuclei for which they can do exact calculations and experiments where they know what they’re going to measure and they know how to interpret it and they know what they’re going to learn. On the radical left were the folks, who in those days wanted to build RHIC and thought they could learn something by smashing together heavy ions. So one had, at least as I think about it, electron scattering in general and (e,e’p) and few-body physics in particular as one of the key motivations for building the lab. Dirk Walecka, who was the very early Science Director of the lab, certainly was a strong supporter of that. Jean Mougey was brought here in the very early days as the guru from Saclay who was doing the experiments there that sort of provided the taste of what might be to come that stimulated things. But how did the process of him coming here and people in the community who wanted to do these experiments evolve into the collaboration that built and then ran Hall A?

Petratos:

Yeah. I was not there when the Hall A collaboration started, but I think I was there soon after that.

Cardman:

Very soon after, yeah.

Petratos:

I joined the Hall A collaboration in 1989. I first visited CEBAF in the spring of 1988. I was a graduate student about to graduate, and I got an invitation to a workshop at JLab with subject design of spectrometers at CEBAF. So, I was asked to give a presentation on the spectrometers of SLAC and some special homemade spectrometers we had built to measure electron scattering from the deuteron at 180° with detection of recoil deuterons for elastic scattering at 0°. My thesis was on the structure of the deuteron… the two-body problem. For me it was clear that I was going to work at CEBAF at that time, so I started writing a proposal to measure the form factors of helium-3 and helium-4. I joined the Hall A collaboration. I started traveling to CEBAF. By that time, I had got in a post-doc job with the University of Rochester, and I started attending meetings of the Hall A collaboration. I had one year to do some things, do simulations of the calibration of the two high resolution spectrometers. I was seeing myself down the line ending up in a university which happened and me having graduate students and do experiments there.

So, I don’t know how the Hall A collaboration was formed, but I joined it in an early stage — I believe in 1989 — and I got started. I got involved. I became a member of the coordinating committee of Hall A, the technical committee of Hall A, and then later on, when the apparatus was about to be completed, we had to deal with scheduling the first experiments. Larry was by that time, I believe, deputy associate director.

Cardman:

Yes.

Petratos:

So he asked us to form an Experiment Integration Committee, and so I became a member also of that committee. So, I was very actively involved at that time. By that time, I had moved from a position at Rochester to SLAC, and SLAC was kind enough to give me time and give me funds to travel frequently to Jefferson Lab. I mean what I was going to do at Jefferson Lab was not directly for the benefit of SLAC, but it was indirectly. They knew that was for the benefit of SLAC, too, so I was lucky to be given funds and time. I remember traveling frequently, and also, I was traveling frequently to JLab during my first two years at Kent State from ‘94 to ‘96 with all these committees.

Now it’s some years, but I enjoyed all these years. We were building and designing, thinking how to do experiments with the highest resolution, highest momentum spectrometers in the world, and they turned out to be like this. Finally, they did the experiments that we wanted to do with them.

Then my involvement… Then I got to Kent State in ‘94. By that time, we had already fixed the experimental problem. The Experiment Integration Committee had put in a plan. We sent it to Larry and Larry added his things. What he added was very wise, and sometimes they were different from what we proposed to do. But Larry was right, after all. I guess I have to give you that! [Laughing]

A few experiments were deemed as ones that would fit weekly easily in the first two or three years of the experimental program, and one of them was an experiment that I had proposed on elastic scattering from the deuteron to measure the deuteron elastic structure functions. This was an experiment that… It was, I believe, the third one that ran immediately, a few months after they turned on Hall A. It turned out that the elastic helium-3, helium-4 experiment, for technical reasons, had to run years later. We had to build a high-pressure helium-3, helium-4 cryotarget, and that came later in the program.

So, we had first to build a hydrogen/deuterium target, and that’s where my group played a big role. By that time, I had my group, two very good young people, and they got involved in the development of the cryotarget, in software for Hall A, and in the commissioning of Hall A. The graduate student was Riad Suleiman. He is now a staff member of the Accelerator Division at JLab. Outstanding physicist. Very capable. Also, the post-doc was David Prout, a really outstanding post-doc. These two people helped the beginning in the commissioning, of course with the cryotarget and the software for Hall A. So, this is a summary of my involvement during the first years in Hall A.

I came from Greece in 1980 to do graduate studies. Of course, there was no CEBAF at that time. I had no idea that I could be proposing my own experiments at the national lab in the United States and that this is what life had for me.

One thing maybe that’s of note is that I knew about the ideas for an electron scattering machine because I joined as graduate student The American University group in Washington, D.C., and they were involved in the early discussions and plans for building an electron machine. At that time, I think it was NEAL, National Electron Accelerator Laboratory.

Cardman:

Yes. The SURA proposals.

Petratos:

My first advisor, Benson Chertok, who unfortunately died during my second year as a graduate student — I was his student initially — sent me and other students from American University to a planning meeting for this new machine at Williamsburg. Maybe Larry was there. It was May of 1981. So that was my first exposure to see what became CEBAF.

Cardman:

Not me. In those days I wanted to build a machine at Illinois. It was complementary!

Petratos:

Yes, yes. So, there I got to know that, well, it was not just… My advisor was Jim McCarthy. They were friends and collaborators at SLAC. They wanted to build a 4 GeV machine, probably on the UVA campus, to study what was at that time known as dimensional scaling nuclear chromodynamics. But I realized there were other universities around. There was University of Illinois with Larry behind. There were the MIT colleagues. There were the Argonne colleagues. Oh, there were plenty of people that wanted to do this kind of physics, which I thought, yeah, it was very good idea, okay? I mean everybody was trying to figure out now how nuclei are made, not in terms of nucleons, protons, and neutrons, but in terms of quarks. It was in the actual project to go after, I thought. Well, also I saw how their physics…It was my first conference, workshop or such. Why are people shouting? “No, you are not right! We need 4 GeV machine.” Then I remember other people saying, “No, no, no! 2 GeV will be fine. We don’t really need 4 GeV,” and so on. Oh, it was exciting. So that was my first real meeting, and I remember it right now. Also, there was the first time I went to Williamsburg, a lovely place. Then a year after that in ‘82 I moved to SLAC, where I stayed six years to do my PhD, this experiment there on the two-body nuclear system. So, me doing research later on at CEBAF became a natural evolution of my work at SLAC on elastic, inelastic scattering with electrons from protons, deuterons, nuclei, and so on. So that’s how I got involved into —

Cardman:

You know, if I think about your history there and I think about the evolution of, let me call it the science case for what became CEBAF and I look at where we are now, one big piece of the evolution going from the mid ‘70s to the end of the 6 GeV program is I would call it a transition from a focus on high precision electron scattering to understand the hadronic base description of nuclei to high energy electron scattering to understand the QCD basis for the hadronic description of nuclei. I would have said you were one of the — you know, with Chertok and company at SLAC End Station A — were somewhat of the avant-garde of bringing that twist to the evolution of the program. It’s, to me, a fascinating aspect of the laboratory that having started out with the one motivation and built the machine with many of the characteristics focused on being able to do, for example, (e,e’p) in lead, that we built the right machine. Indeed, it could do both…

Petratos:

Yes. Yes.

Cardman:

…and now has an extended life with higher energies in the smaller distance scales. I would say completing the valence regime understanding of that problem, to use Nathan’s description. Well, we’ll see where it goes.

Something that occurred to me as we were thinking back — we were talking with Bill Bertozzi a little bit ago about Hall A and its evolution. One of the things that came up was a serious technical problem early in the life of Hall A, which was the discovery that the hexapole windings were rotated 90° compared to what they were supposed to be.

Petratos:

Yes.

Cardman:

Something I remember coming out in many, many discussions after that was that in many ways the Hall A spectrometers were designed for lead-208 (e,e’p) as opposed to being designed for the light nuclei, the difference being in one case position resolution matters more, and in the other case angular resolution matters more because of the kinematic broadening. The optics experts pointed out that had we been thinking properly about what we wanted to do in Hall A (focus on lighter nuclei), that we would have designed the dipoles as uniform fields instead of these indexed fields, and we wouldn’t have worried so much about all the multiple corrections in the quadrupoles and so on because what was going to matter was getting good angular resolution from the target to the focal plane. I wonder if any of that impacted you, if there were any discussions of that sort of thing, or if Mougey just sort of dominated with “This is the way we’re going to build it. Live with it.”

Petratos:

Well yeah, there were many discussions, and there was some evolution. When I got in the Hall A collaboration, I believe the design of the Hall A spectrometers was not fixed. Actually, at least one of the spectrometers was not bending in a vertical direction the way Mougey had it.

Cardman:

Initially they were both horizontal.

Petratos:

It was bending in the horizontal direction, and there were chambers in between the magnets. It was not the greatest idea in the world. The spectrometers have to bend upwards. That’s how you do electron scattering.

Cardman:

Won’t you be amused —

Petratos:

There are some things that I had spent ten years of my life at SLAC working on spectrometers. I mean I had designed or modified several spectrometers. There were some flaws in the Hall A spectrometers — even in the Hall C spectrometer (the HMS), which once I dared to say in a user’s meeting. I believe it turned out to be that better than 10-4 optics resolution of Hall A was overkill. I don’t think… Maybe one hypernuclear physics experiment needed this resolution. We compromised the angular resolution of the spectrometer by getting some resolution in position resolution. Figure out where the events came from the target. I then went for angular resolution instead of position resolution. Of course they were not going to do any (e,e’p) experiments. I would have designed the spectrometers to have a good angular resolution and then have an alternate optics tune for position resolution.

Oh, also… Yes. Larry said that the dipole had no parallel plates.

Cardman:

That that would have been better for light nuclear systems because it would have facilitated getting the angular resolution improved.

Petratos:

Yeah. Okay…

Cardman:

No field in there.

Petratos:

At least I could have designed them. So now the cross-section of the two dipoles and the two spectrometers is a trapezoidal shape. I would still make them with a trapezoidal shape, but in the opposite direction. In other words, the big side of the trapezoid now is at the bottom or the top. Both of them are —

Cardman:

Larger radius, yes.

Petratos:

This would have been the best because the way they are now, you lose only about 50% of solid target. I mean 50% of solid target just leads to —

Cardman:

The answer is it gives you better position resolution. Okay? It’s n = ½. It’s a classic.

Petratos:

I’m not sure about this, Larry. Anyway. So, there are some things that because I had started them at SLAC that I thought they were not exactly right. Like in Hall C, for example, the third quadrupole was put before the dipole magnet. That ultimately made the length of the hall much bigger. Less resolution and momentum was obtained by this scheme, but also the length of the hall became bigger. That increased the civil engineering costs. Anyway, there were discussions, yes, on optics. I remember John Domingo not being happy with Jean Mougey’s spectrometers that were moving in the horizontal angle in meetings. There were fun times. At the end, yes, things were built maybe not 100%, say, optimal, but 90-something, and that’s the way science is done. No one does things perfectly.

Cardman:

You don’t know what perfect would be until after you’ve done all of the experiments! [Laughs]

Petratos:

Yeah. A colleague once said you don’t know how to do an experiment unless you do it fast. So yes, now… Though in thinking back, maybe some things we would have done them a little bit differently, but a few things. I mean I think that what we built did what it was supposed to do. We did the experimental program that CEBAF was built to do: parity measurements, few-body form factors, (e,e’p), deep inelastic scattering, learn more about the quark parton model, and more also. More of these things than what we first thought we were going to do.

Cardman:

Can you think of any other burps and hiccups along the road that were interesting bits of the evolution of Hall A?

Petratos:

No. I don’t remember something that I would say all was not done right or it was funny or should not have been done that way. I mean I think if we had to do it all over again, we would have done it 90% the same way. Many good people got involved. I mean the best electron scattering scientists got involved, I’d say, at CEBAF at that time in Hall A. I had the good fortune to work with many distinguished colleagues at CEBAF. I had the fortune to learn electron scattering from colleagues at SLAC, Ray Arnold, Peter Bosted. I had the opportunity to work with Charlie Prescott later on on spin structure experiments. So, I was fortunate to know all these colleagues. They influenced my career. I learned from them. Yes, Larry. Go ahead.

Cardman:

I was going to say one of the things Catherine is interested in is the sociology of the collaborations. So, if I think about Hall B, it’s as close in approximation to a high energy physics collaboration as we have in nuclear physics, though imperfect in that regard. On the one hand, people at least had to sign up for shifts for every experiment whether it was theirs or not, but there were sort of broadly overlapping physics subject areas using CLAS with different subelements. If I think about Hall C, it’s really several, almost independent collaborations with relatively little overlap — you know, the parity guys, the hypernuclear guys, and so on. In Hall A, my characterization would be it’s a few — three, maybe four broadly overlapping collaborations where there are many people in each collaboration who participate in at least one of the other, let me call it sub-collaborations. So for example, the group that’s interested in few-body physics, a group that’s interested in parity violation, a group that’s interested in (e,e’p), and so on. I’d be interested in your thoughts about the characterization and how it works.

Petratos:

Yeah. Our collaboration was a few people, as Larry said it, who wanted to do (e,e’p), a few others to do few-body physics, a few others to do parity violation studies. But the perception in the CEBAF community was, “Oh, these are the classic (e,e’p) guys, so they want to do…” That’s how I was feeling that time, whereas (e,e’p), that’s something that was probably a thing of the past, not a thing of the present. Still we learn from (e,e’p) short-range correlations, how the nuclei interact with each other at the short scales. That’s something that’s of interest to the science that we did.

One thing for Hall A that we knew, and sometimes we thought that we were not that strong because of this, is that we did not have too many in our collaboration, too many of the really big, powerful groups. MIT and Bill Bertozzi was in Hall A. Okay. Maybe he was the biggest name in the collaboration, the senior person from MIT, but our collaboration did not have many MIT’s in it. It had lots of Kent State’s; I can tell you this. I think we had this very complex of inferiority compared to Hall B and Hall C where the big powerhouses were in those collaborations, but then we did well and we got some very good physics out.

Cardman:

I can only tell you when I sat back at the end of the 6 GeV program and looked broadly at what had been accomplished and things that struck me as highlights, you were pretty evenly distributed among the three halls.

Petratos:

Yeah. Well, we did well. Maybe some people thought we were just the (e') folks in the lab and we were going to do (e,e’p). Well, we were not, and at the end we did very little, I believe, (e,e’p). The bulk of the Hall A physics was not (e,e’p). I believe that’s the only — how can I say? — sociological aspect that I have noticed, that I was aware. Well, at some time, I don’t know, since you are asking, we felt and I felt that, well, because our group was not made of too many MIT’s, we were not given a fair shot at workshops, at conferences, at JLab events. We have made this known at one point. There was some unhappiness, but maybe these things happen in other laboratories. Maybe some groups sometimes feel that they are not recognized fully. Their contributions may be ignored and so on. But it was a good environment to do science, and it is still a good environment. I was always happy traveling to the lab. It was a highlight of my life to go to meetings and do experiments there, and I think other colleagues share the same feelings.

Cardman:

And I would say to you it’s my definite impression that Kees did a really first-class job of, on the one hand, keeping the collaboration coherent and moving forward, and on the other hand, putting forward the quality of the science you guys did to the community at large. I can only tell you for sure he did a damn good job of it within the Physics Division.

Petratos:

Yes. Under Kees’s leadership, Hall A was very organized. We knew exactly what we were going to do, how to do it. Things moved on time. You were schedule that one day, and yes, you were starting taking data at that time. I have to say about John Domingo also I remember him in the first time, the first meeting where we still were under design. I remember his common sense and stepping in. When he stepped, he had to stomp. He would say, “Come on, guys. Get serious,” and he was right. We were not serious sometimes, and John made us serious. I think we were fortunate also not only to have Kees as Hall A Leader, but John Domingo also as the Physics Director, and of course Larry named as the Physics Director. As I said, Larry also strengthened for us for the collaboration the Experiment Integration Committee plan. The first few experiments went smoothly, and the program started as it should have started, in a logical, ordered, and started producing sound results.

Cardman:

My recollection is that the broad goal we had set each of the hall collaborations was to come up with a plan for roughly the first year of physics that on the one hand resulted in full commissioning of all of the apparatus and checking it out, and on the other took account of the fact that in the very early days of any new piece of equipment, you have something less than the ultimate performance that you’re going to expect. We tried to set the goal for you guys of, on the one hand, commissioning as quickly as possible, and on the other hand getting out as much good physics as you could in the process. It was sort of interesting watching how each of the three halls worked through that problem. As you said, I think Hall A did a very nice job. It came up to snuff clearly comfortably in a year and was doing some nice stuff on the way.

Westfall:

How about Jean Mougey? You didn’t mention him. Did you overlap with him at all?

Petratos:

Yes, I did overlap a lot. We had many, many discussions. I met him first as a graduate student at SLAC. He came to SLAC to propose an (e,e’p) experiment at SLAC. I don't know… Anyway. He asked me to apply for… I think that was after my talk at the 1980 workshop at JLab on spectrometers. He asked me to apply for a staff position in Hall A, and I got to know him. It turns out that I got twice an offer from Jean Mougey to come to JLab, and the offer was declined. Everyone has done some blunders in their life, so I have done my blunders, too, for not coming there as early as 1989 to Jefferson, to CEBAF at that time. Yes. I think Jean was liked by the Hall A members. His focus was (e,e’p). He tried to steer the design of the apparatus to maximize the efficiency for (e,e’p) experiments, but at the end, the spectrometers were designed for general use. It’s been, I think, a pleasure to have worked with all the CEBAF management all these…Now it’s…Oh god. Is it more than 30 years?

Cardman:

Yes.

Petratos:

Yeah. Now it’s more than 25 years. Yes. Yes, I have good memories from CEBAF and Jefferson Lab and now for something else, and I’m still really involved. I have gotten a sabbatical and a special research leave to come to the lab next year for at least a year for another experiment.

Cardman:

One hopes it continues for at least another decade.

Petratos:

I feel fortunate, Catherine, that I have been part of Jefferson Lab.

Cardman:

Are there any obvious things we haven’t thought about to chat with you about in the Hall A evolution and early days?

Petratos:

No. You asked for our technical decisions. I believe more or less we did things right. I gave you some thoughts on the sociology of the collaboration at that time.

Cardman:

Yes. So, Catherine will arrange to get this interview transcribed. We’ll ship it your way for review, and if in the process you have a few more thoughts, please feel free to pass them on.

Petratos:

Okay. Catherine, if you think of any other questions, please email me. Call me. We can talk on the phone if you want to.

Westfall:

Thank you very much.

Cardman:

Thanks for your time.

Petratos:

Thank you for doing this.

Westfall:

It’s thanks to Larry.

Petratos:

You initiated this, Larry?

Cardman:

This particular interview? Yes.

Petratos:

No, no, no. This…

Westfall:

The history.

Petratos:

The history.

Cardman:

So to be careful, Catherine was originally doing the history program in Hermann’s era, and it sort of got stopped for reasons I don’t even fully understand. Hugh Montgomery (Mont) agreed to restart it, and it’s become my responsibility to oversee it on behalf of the lab. So, I am the liaison. I’m also one of the few people who’s been around for most of it. [Laughs]

Petratos:

Yeah. Maybe, Catherine, I have to tell you a personal story. Larry should remember this. In Hall A, I told you we were feeling like the hall that was not the favorite hall in the administration. If somebody had to get some budget cuts, it was going to be Hall A. At one place, there were rumors that maybe one of the two spectrometers in Hall A would go. I got terrified because for my experiments that I had proposed, I needed two spectrometers to do coincidence between electrons and recoil nuclei. So, in one user meeting — now I don’t remember. I think it was summer of ‘93; I don’t remember. In a user’s meeting, I asked Hermann Grunder. I raised a question. I said, “Are we going to build after all two spectrometers in Hall A? Because there are rumors on the street that maybe one of the two HRS’s will have to go.” Hermann did not like my question, and he said something, “How do you dare to ask these questions? You know the answer. Don’t ask again.” I said, “Hermann, excuse me. I mean I asked a question. Will you say yes or no? Are we going to build two spectrometers or not? Are there any thoughts?” I was a bit naïve. Oh, Hermann dismissed me, and I said, “Hold on. How do you dare to do that? This is a user’s meeting. This is my meeting. I have a right to talk and a right to ask the direct questions.” Oh, Hermann Grunder did not like this. [Laughs] Anyway, that’s one personal thing that I remember. Once I stood out and…

Cardman:

I feel obliged to point out that not only was one spectrometer in Hall A potentially at risk, but all of Hall B. So, it’s hard for me to sit quiet when you claim that you were the stepchild.

Petratos:

Yeah. So, I don’t blame Hermann. Maybe Hermann would say, “This guy talks about one spectrometer in Hall A, and maybe I don’t have money for half of the three halls.”

Cardman:

For what it’s worth, I would tell you it’s my broad understanding that in the very early days, the plan was that Hall C was going to be empty with a $5 million trust fund for experiments to be built in the future, and it was going to be Hall A and Hall B, right?

Petratos:

Yeah.

Cardman:

When it became clear (a) that there was something that made sense to be built in Hall C and that that was going to further strengthen the user community at the lab and so on, and also that the total cost of everything in the experimental equipment and accelerator was slowly going up, they came up with this concept of spinning off half of the experimental equipment, which ended up being one of the two spectrometers in Hall A and all of Hall B, into this outside the new construction project that was called ACE (for additional capital equipment). I actually believe, though I don’t know for sure — this is just rumors I heard way back when — that part of the reason for doing the split the way they did and including a piece of Hall A in it was that of course the (e,e’p) program was one of the primary motivations for building the lab for much of the community.

Petratos:

Yes.

Cardman:

So not including that in what you built would be sacrilegious, and therefore it strengthened the case for doing the additional capital equipment. So, I don’t think it was because people thought the Hall A program was of lesser importance.

Petratos:

Yeah, I don’t think that. Yes.

Cardman:

Okay. I felt obliged to clarify.

Petratos:

Yes. Let me add to this. I knew initially Hall C was not going to get any — now I remember — any spectrometers, general purpose spectrometers.

Cardman:

Nothing!

Petratos:

The workshop that I went to CEBAF, which happened — CEBAF was nothing at that time. It was two trailers in the VARC Building. The workshop was at the only hotel, or at one hotel close to the highway. Years and years ago there were no… VARC had only one room for workshops.

Cardman:

It was probably a Howard Johnson. The Omni wasn’t here then.

Petratos:

Yeah, Howard Johnson. Yes. It’s near the post office. It was a hotel with a conference room near the post office, now near the civic center that they have built, the new… Anyway. So that workshop was to talk about spectrometers, ideas of spatial spectrometers for Hall C. One idea at the time was to get the 8 GeV spectrometer from SLAC and get it to CEBAF to be used in Hall C. I believe that was a serious idea at that time.

Cardman:

Yes.

Petratos:

I believe SLAC had been asked for this; I know it, and the answer was no because SLAC could see down the future that 20 and the 8 GeV spectrometers, they had the most powerful conventional ion-dominated magnets in the world for fixed target spectrometers. They were not going to give them away. They were used in other experiments in [name]’s lab at SLAC on the nuclear spin structure program. So yes, I remember that, that Hall C was not going to get any general [???] spectrometers.

Cardman:

I would note that it’s a good thing that SLAC spectrometer didn’t come here because the one we eventually built had an order of magnitude bigger solid angle.

Petratos:

Yes, yes.

Cardman:

It helps! [Laughs]

Petratos:

It helped. It helped, and saved ultimately the money to power costs because these magnets were 1 megawatt magnets. They were really power hungry, and they were used in a very important science program at SLAC. So, things have worked that way that everybody got their science programs and all the apparatus was used.

Cardman:

And not wanted here! [Laughs]

Petratos:

I was a member of a three-person committee who recommended to dismantle the End Station A spectrometer at SLAC after the Loma Prieta earthquake. They were unsafe. You feel bad, you know, recommending to tear down what others that had got the Nobel Prize. I was staff at SLAC at that time.

Cardman:

Well, we thank you for your time and hope you find with amusement the words you said are words you meant to say.

Petratos:

Thank you.

Westfall:

Thank you very much.

Petratos:

I will scan. You will receive, Catherine, a message from some scanning machine.

Westfall:

Oh, okay. From you.

Petratos:

Yes, from me. Good evening. Thank you.

Westfall:

Thank you. Bye-bye.