Daniel Kennefick interview with Lee Holloway

0:00 So it's 2.30 in the afternoon on the 5th of September. So you were telling me about how you're about to do a high-energy thesis today. Yeah, I spent a sabbatical year in Pisa a number of years ago. I think it was in 1909. And I was working on the CEF photon-antipod-1 collision. And there was a CDF group at Pisa, so I decided to work with them. And while wandering around the laboratory, it turned out to be Alberto Giazzotto's initial attempt to build a seismic isolation stack. I don't know if you've seen pictures or heard about his old idea. It's essentially a compound pendulum, six or seven stages. For example, a simple pendulum at some stages of the meter. You have to damp out the vertical motion as well. So he devised a gas spring, which had quite low frequencies. So he had these sudden tanks of gas springs suspended almost seven meters tall. There's a lot of work involved in the suspension system, and it was quite unbelievable that it worked. Later on, it was abandoned, and anyway, I was exulted. It was a very engaging following.

2:30 So I worked with him just a little bit, and got involved with, I was associated with seismic isolation. I came back here to Illinois, trying to get some money from the NSF application. One of the reviewers said, why should we give away a holiday ticket? Anyway, I did manage to get some money from the university and had a student, a graduate student. We did some experiments on an idea that I had of using an inverted pendulum with the lowest resonant frequency isolation staff. The point is that the lower you can make that lowest resonant frequency, the more damping you'll get because of the... And so on and on and on and on and on and on and on and on and on and on and on and on and on and If you have a mass on top of that, this thing has a resonance frequency. But as you make the mass more and more, the resonance frequency goes down. And if you make the mass too big, it will fall over. So what you want to do is to adjust. The string constant, the restoring force, and the mass, this is going to make that resonant frequency quite low.

5:00 Well, in fact, it works. And I built a prototype device here down in the basement. And we had it suspending 600 kilos. Regularly at a resonant frequency of about 80 millihertz. And then I got involved with the development of sensitive accelerometers in order to apply electronic feedback to the system for additional damping. If you can sense the acceleration of the masses, pump an accelerometer up there, and if you can sense the acceleration, you can... ... and generate an electronic signal to push back and freeze it. Anyway, I kept my interest going and then last year, another sabbatical, seven years later, another sabbatical, they go back to Pisa. So I went back to Pisa and worked with all last year. Convinced them to in fact adopt this inverted pendulum idea. So we did, and it's now been engineered, and we now have prototype devices which are chugging along cheerfully at 50 millihertz. It looks weird. I mean, this thing is six meters tall, and it holds up a ton and a half of junk, which is the main suspension system. And it works. That's my small contribution to the field. So you'd be continuing to work at the Baywood? Yeah, there's not much I can do here from the point of view of actually working on the detector itself.

7:30 It's now in an engineering stage. So I can't do much here. I've been thinking, trying to think about data analysis, waypoint analysis, just on my own. I plan to try to go back to it, retire to semi-retirement over there. What kind of data analysis? I've always been interested in neutron pulsar, trying to pick out a neutron pulsar and all those things. There's only been a fascinating study aware of course of the problems of the motion of the earth around the sun and the secular motion of all kinds of things and so I've been looking into algorithms and how do you and what All of these fields are related to the gravitational power that we use in a signal that we know is expected to be small at best and so we have to look at them for a year or so and during that time the Doppler shift is pretty formidable and since the Doppler shift depends on where the neutron star is with respect to the orbits. We have two linear bins and apply a different algorithm to the linear bin, and then the computational units on the algorithms. Perhaps make a simple problem using the shorter time ranges, sample size, and then patching these shorter time ranges together. I think there's some people at Caltech working on it too.

10:00 Yes, they'll do it. That's really interesting. Hierarchical, it's called hierarchical in the academic dimension. Well, since you're interested in the signals from neutron stars and neutron star binaries. Not binaries. Just the neutron star. Where there's a bump on the neutron star. Yeah, what kind of... has there been any basis on which... Do you have any predictions that have been made as to the source that can be expected for the... Yeah, oh yeah, people have looked at it, and the answer is it's small. You can sort of tell what's at the top. People look to develop the possible source of the form of the element, so you're also saying that the magnetic fields in these things are Then you can ask, what is the highest possible mountain you can have in a neutron star before a starquake from the Pacific? And you can look into solid-state physics, material properties of neutron star matter, and what sort of stresses it can sustain before it can be solved. At least there may be something else in the book. Must be something. Yeah. Anyway, I think it's a fascinating subject. What's the advantages that the signal might be somewhere? Oh yeah. Once you find it, you can point to it with absolute security. I mean, it's there. There's no ambiguity. We have the moon, which imparts another shift to effect.

12:30 So you have three axes, and you just nail it down to the outside of it, so you can actually point to the outside of it, and I think it's fairly clear that the neutron stars that we would observe would be in our own galaxy, so you don't have to look at outer outer space, which makes another point that you should look where the light's shining. You may want to concentrate the initial searches for the center of the galaxy, so you can see what the standards are for the increase in asteroids. So you want to look for all the stars? Yeah. A lot of people, it's not right to look for the light. So you just focus on what you've asked for? Yeah. Yes, the neutron star binders. So I have been going to ASPEN. I don't know how much interest you have. I have been going to ASPEN for what you made of this research, but it probably wasn't as active as... Oh, well, I was in ASPEN last January when they were there and gave a speech about their new thing, and I came home and I talked to Steve. I don't know about it, and you said they were full of beans, so I don't like to argue about it. I'm a poor energy physicist, I don't know. Well, I get it. I've talked with other people, and I think the general consensus of the people I've talked to is that it wasn't. The reaction of, I guess, the afternoon was largely for a lot of what was going on.

15:00 Well, I mean, the reaction was certainly interesting because it had a significant effect on the experimental population. By the way, it's not so bad for Virgo as it is for LIGO because it tends to chop off the higher frequencies where LIGO is the most sensitive. Virgo, by the way, has a much lower. The first stage of LIGO, I think the product frequency is 100 Hz or something like that. So there was certainly great interest in them at Aspen. Yes, certainly. Well, I was going to just ask a couple of questions about Virgo, which is a project I know a lot less about. When is it expected to go online? Oh, the same time as LIGO, more or less, near 2000. These things have some tendency to slip. They're unlucky to get closer to it. Yeah, we're supposed to start building suspension towers. We've occupied the land by using civil construction, but these things take a lot of time. Also, in Italy, things happen that you don't expect.

17:30 It's located near a little town called Cascina, which is about 15-20 miles mainland. It's a farming community, fairly level. So it's convenient to be there. Unlike some of the American sites, choose between tundra and strong. So they're coming along pretty well. And the arm length is about three kilometers? The arm length is three kilometers. What would be the other salient differences between these two? What is the difference between the two? It's not very clear. Perfect. Yeah. So do they have much smaller bin tubes than mathematics? I don't know. I mean, there are no libraries. I mean, the problem is, you see, you have to have a big enough cube in order to get this true life baffled correctly. Because that is a serious problem. You use a stage motor.

20:00 So then China has a network of detectors. Do you know anything about the detectors? Well, certainly there is a communication among the detectors. We certainly correlate timestamps. And there have been talks about having single data families. I don't know how far that's gone, but there is certainly communication going on between LIGO and Virgil. Like, similar to LIGO and Virgil, a bunch of energy physicists. There's the French group from Honesty who are formally working at CERN. The group, of course, they accelerated with the Lennarty and Leibniz picked up the SLC. Yes, that's right. I suppose the experience of psychology, physics, preparatory for building. Absolutely. Preparatory for building, not being afraid of building. Oh, John Sokol himself was a designer. Oh yeah. I mean, also the construction of organization. How do you build something big? How do you organize it? All of that, those techniques are well-developed. My CDF collaboration had 400. It takes a certain amount of skill in how you do it. All these skills transfer naturally over to a big project, like a theory.

22:30 It's a serious problem. I mentioned Lillian Hodeson a moment ago. I used to have the occasion to drive with her back and forth between Fermilab and Geo because she was... We discussed many times the social differences between condensed matter experiments and high energy types and she said that day and night the condensed matter people were sort of in a certain sense very socially She says there's an amazing difference between them. So presumably the gravitational wave, I mean, has it taken over a lot of the Mars? Yeah, with some reluctance, I might say. But, you know, the technique is new. So there's a second wave of clusters now? Yeah, absolutely. Particularly the laser people. They're, you know, you want to put them into a box, you put them into a box. So they were coming from that culture, so it was necessary to give them a side of the scale. Oh yeah, it's now a big science, WBS, huge notebooks for project management. I noticed in the Lago office at Canterbury, there's this huge chart. Yeah, and what group builds this piece of apparatus when it's charging? Virgo is also answered by the fact that they have two separate government agencies, the trans, writing the show, and that makes it a little bit tricky.

25:00 Well, I feel since they're going to contact us, it's going to be a little bit tricky. Do you have any kind of a feeling for the likelihood of getting any attention from that kind of students? I have no clue. Anyway, this will be fun. Yeah, sure. Especially when you're writing a seminar. Just because you know you're probably not going to be around anymore when they detect anything. This is the first one. I hope I can't get in there long. I can't find it. It's a seaside. Oh yeah, hopefully. But of course, you guys are going to be gone somewhere else. Well, thank you very much. Okay.