View from the Inside
Talking with Peter Rosen, Associate Director, Office of High Energy and Nuclear Physics
by Nona Shepard
ES News: The Office of Science has just published its Strategic Plan, which has lots of wonderful, important experiments in it. Peter, we'd like to hear what's important to you about the Plan, and what would you like to tell people about those projects?
Rosen: Of course this is a parochial remark, but I think the Plan underplays the role of High Energy and Nuclear Physics in the Department of Energy. I don't know if it's a fair comparison, but I think of the accelerators we build as analogous to the cathedrals of the medieval world. Those cathedrals are wonderful buildings that were built to the limits of the technology at the time. As achievements, our projects have been at the limits of technology of modern times in the same way.
ES News: That's a romantic way to think of it.
Rosen: Well, our lineage goes all the way back to the Atomic Energy Commission and the Manhattan Project, and so we were present at the founding of nuclear physics. High Energy Physics was something that grew out of nuclear physics in the 1950s and the 1960s and became a separate subject. That's a scientific lineage, if you like, and also a national lineage in the sense of being related to issues of national security and, today, issues of economic strength. I believe that maintaining high energy and nuclear physics at the frontiers of the field is an important element of our national strength.
ES News: How so?
Rosen: The reason I say that is partly because of the science involved. We are dealing with the fundamental properties of matter and energy: What are the fundamental constituents? What are the forces between them? We're driven by very difficult problems that people haven't dealt with before; and inevitably when you do that on the scale on which we work, you invent all kinds of new things to solve your own problems and then, lo and behold, they become applicable all over the place.
The technologies we've developed have spread out into other areas
of science. For example, we are the field that led to the development
of accelerators over a tremendous range of energies for both electrons
and protons and heavy ions, and in turn, those accelerators
have become tremendously useful, from the small cyclotrons
used by hospitals to produce short-lived positron emitters for PET
(positron emission tomography) scans to the proton accelerators used
for certain types of cancer therapy. Accelerator technology is the
basis of the Spallation Neutron Source, and the neutrons you'll get from
it are very important and, likewise, the photons you get from
light sources are very important for material science, biology, and so
on. Similarly proton accelerators can be used for proton radiography,
an important element of science-based stockpile stewardship in Defense
Programs.
ES News: People don't realize how big your projects are.
Rosen: Nor do they realize how difficult they are. Each one is very delicate in a certain sense. You can't just build them, turn on the switch and, lo and behold, they run. It takes a lot of work to get them to run and any little problem somewhere around the ring can cause it not to work as it should. So you have to take a tremendous amount of care, and you have to be watching them all the time, because small changes of one kind or another will interrupt the way they work.
ES News: It sounds like your projects would be bears to run. How do you do it?
Rosen: We've had a lot of experience managing these large physics projects as, over the years, we've built larger and larger projects. Our basic technique is, first of all, to understand very clearly what is involved, and secondly, to watch them on a steady basis. We go out and review them at least every six months and, if we see that things are not moving as well as they should be, take corrective action at that point. It does involve a continuous process of reviewing, keeping in touch, understanding, recognizing.
ES News: Are there lessons from the experience of the SuperCollider, which we started to build and then shut down?
Rosen: Yes, there are lessons from that. It's a very unhappy episode. I think that one of the fundamental mistakes was that the cost of the SuperCollider was allowed to grow. Maybe people can justify it on a technical basis, but from a governmental and political points of view, you can't afford to do that. If you make an estimate that something is going to cost so many dollars, in my view you are making a commitment to build within those dollars. Of course, you've got to allow a little tolerance, a few percentage points off here or there, but not a factor of two or not a factor of 50% or anything like that. It's got to be at the margins where you might have a little flexibility.
ES News: Are you talking about the construction phase or other phases as well?
Rosen: Well, it's a mixture of construction and design. You want to make something that will work, but not necessarily gold-plated. You want something that will achieve not necessarily your ultimate goal but some intermediate goal, which is still a very valuable goal from a scientific point of view. You build to that intermediate goal with the idea that in the future you will be able to upgrade it to a higher energy. There are all those things to take into account. And, as I mentioned, you are doing things people have never done before.
With the SuperCollider, no one had ever made an accelerator with a circumference of 53 miles. The Tevatron is 4 miles around and that was the largest ring until the LEP (Large Electron Positron Collider) ring at CERN (European Laboratory for Particle Physics). That's about 15 or 16 miles in circumference. But, neither one of those is large compared to 53 miles. The magnets used in these projects are not easy to design. They are very special magnets. They are not the kind of thing that you can go and buy off the shelf. So all of those things can add to the cost of the machine.
ES News: How many specialized facilities does your Office direct?
Rosen: This Office is responsible for Fermilab, SLAC (Stanford Linear Accelerator Center), Thomas Jefferson Laboratory, Brookhaven Lab's RHIC (Relativistic Heavy Ion Collider) accelerator, and some smaller accelerators; one at Berkeley, one at Argonne, and one at Oak Ridge.
ES News: You said that not only are these physics experiments important for the national security but for the scientific eminence of the United States as well. How does the International aspect of your program fit in?
Rosen: Well, first of all, science has always been international. In the era before the Second World War, Europe was preeminent in our field; people from the US would go to Europe to study. But with the rise of Hitler in Germany, things began to move over to this side. After the Second World War, certainly, the US was preeminent in the field; participants came from Europe, Japan, and all over. And now, any major accelerator has collaborations of scientists from many parts of the world working at it. For example, the B-Factory at the Stanford Linear Accelerator Center has just commissioned the detector BABAR, which was built by an international collaboration of about 600 scientists, roughly half of which are not from the US.
At CERN, where they are building the Large Hadron Collider (LHC), which will be the world's highest energy proton accelerator when it is completed, the laboratory has always been an international collaboration of European member states; but US physicists have always worked there. At the present time, for example, there are about 200 to 300 US physicists working there. When the LHC is completed, there probably will be about 500 to 600 US physicists working at that laboratory.
ES News: Obviously, your Office is involved in that exchange.
Rosen: Oh yes. There is an international agreement, signed in 1997, that commits DOE to providing $450 million towards the cost of the LHC. The National Science Foundation is providing $81 million.
ES News: Is that in dollars, or people and dollars?
Rosen: It's largely "in kind" in the sense
that certain parts of the accelerator and detectors for the LHC are going
to be designed and built in this country and then shipped to CERN.
In addition, CERN is committed to buying $200 million worth of
materials from the US for other parts of the accelerator. For example,
the magnets are superconducting magnets that need special materials and
a large amount of those materials will be purchased in the United States.
So most of the money is going to be spent in the US, and the goods and
the people will then move over to CERN.
ES News: And International groups come to work at our labs, don't they?
Rosen: Oh yes. At Fermilab, for example, there are two big detectors (Fermilab is the world's highest energy accelerator and it will have that honor until LHC turns on in about 2005 or 2006) and scientists from Europe, Japan, and India are taking part in those experiments. At RHIC, building the two big detectors involved many Europeans, Indians, Chinese, and Japanese physicists and engineers.
The field is very naturally international because the laws of
physics don't change when you cross a border from one country
to another.So, in that respect, I think we're pioneers. I think
we're an example of how different countries can work together effectively
in the pursuit of science. We have a goal, which is to understand
certain things from a scientific point of view and we're capable of working
together. I think that other parts of the international sphere should
look on us as a model to follow.
ES News: Not only are your projects uniting physicists from all over, they're interdisciplinary as well.
Rosen: Yes, they are. I mentioned that
our work has been applied to many other fields. Well, we've also borrowed
back, too. A lot of our detector technology is developed by high
energy physics, but it rests very much on condensed matter physics, or
sometimes it rests on chemistry or some combination
of condensed matter and chemistry. We make use of what other sciences
have to offer to solve the problems that we're interested in.
ES News: Like what?
Rosen: Computing, for example. We have these great big detectors, we record tracks electronically, and we have to reconstruct what happened from all that electronic data. You're dealing with how to go from a set of data to an image of something, and these kind of imaging techniques then find their way into medical imaging. A lot of things depend on either nuclear phenomena or computing techniques similar to the ones we've used or outgrowths of the ones we've used. And computing is becoming more and more important. As detectors and accelerators get bigger and bigger, the scale of computing grows tremendously. It gets to a point where you can't deal with the computing incrementally. You have to change your methods qualitatively, so we're doing things like that as well.
Remember that this field invented the World Wide Web in order to transport vast quantities of scientific data from CERN to other laboratories, including labs in the United States. In many ways, it all goes to prove that dividing sciences up into different areas is okay, but there are a lot of connections between the different branches. From a point of science policy, I think you should pursue them all and apply your resources to all of them to make them move forward together.
ES News: What's new on the research horizon?
Rosen: There's a very exciting idea called the muon collider. Muons are particles that are very similar to electrons, but they're very heavy200 times heavier than an electronas a result of that, they have a lifetime of 2 microseconds. That may seem like a very short lifetime, but in the world of particle physics, it's a very long time. That can get stretched out if the muons are traveling very fast relative to us here on Earth; the special relativity phenomenon of time dilation can stretch them out so the higher energy they have, the longer they will live, or at least we think they live. Scientists want to build circulating beams of muons and make them collide, which is a fascinating idea. We don't know if it is really feasible at this point and there is a lot of work that has to be done to see if it is feasible.
ES News: And to see if it's worthwhile (except intellectually)?
Rosen: From a physics point of view, there are certain very interesting questions that make it worthwhile, if you can do it. The muon decays into an electron and two particles called neutrinos. Neutrinos are particles that react extremely weakly. They can travel through a light year of lead without doing anything. But we are very interested in the properties of these particles, and the muon rings could be a very intense source of these neutrinos. That's like an intermediate stage, you could build a ring that produces neutrinos as you investigate the way of accelerating the muons to higher energies and then making them collide. So that's an idea that has gotten this world very excited. And there are tremendous connections between nuclear physics and high energy physics with the world of cosmology and astrophysics. A lot of processes that go on in stars are nuclear processes, and, in fact, we believe that all the elements were manufactured by supernova explosions, which are giant fusion reactors.
ES News: Have you anything else to tell our readers?
Rosen: Oh, I was going to pick up on your use of the word "romantic" because I think this is a field of people who will go anywhere to do their experiments. And that's a tradition that goes all the way back to Albert Einstein. I think it was the year 1919 when, in order to prove his general theory, he had to observe an eclipse to see the light from stars bending around the sun. So people went to chase the eclipse in order to measure the bending of light, and that was one of his great successes.
People flew in balloons and climbed to the top of mountains in the 1940s and 50s to study the properties of cosmic rays. Astronomers are the same waythey will go to wherever they can get a clear sky.
Our people will burrow into mountains. In fact, in Italy, there's a road from Rome to the eastern coast that goes through the middle of the mountain; and off to the side of the road, underneath that 4,000-foot-high mountain, they built a great big laboratory.
We've had people do experiments in gold mines in South Dakota. We have a big experiment going on right now almost 7,000 feet down in a mine in Canadathe Sudbury Neutrino Observatory. There is another big detector in Japan that is deep inside a mountainthe Super Kamiakande. The Super K consists of a ten-story building filled with 50,000 tons of continuously purified water observed by more than 11,000 giant photo-tubes.
 Peter Rosen (center) deep underground with the crew at the Sudbury Neutrino Observatory |
So, people will go where it's necessary to go to do their experiments. In that sense it is a romantic field, and it's an adventurous field. It's not only intellectually exciting, but it's humanly exciting too. I guess it attracts a special kind of personan adventurous personfor that reason.
ES News: Your enthusiasm is exciting. Do you miss doing the research?
Rosen: Well, I've been involved in this field for more than forty years, and because I'm a theorist, it's relatively easy for me to steal a little time to think about physics. Given all the intense non-physics problems you have to deal withadministrative problems, political problems, people problems, and so onit's therapeutic every now and again to get away into a world where you're in charge and where no one else can intrude into what you're doing. You concentrate very intensively when you get into these things, and someone looking at you might think that you're day dreaming, but you're not. There's a lot going on inside here.
ES News: I'm sure of it. Thanks, Peter, for talking with us.
See the website for more information about the projects and programs of the Office of High Energy and Nuclear Physics.
The New Strategic Plan and accompanying Science Portfolio are available online from the Office of Science website.
To obtain a printed copy of the Strategic Plan, send a request along with your mailing address to Mrs. Silillian Anderson
U.S. Department of Energy
Office of Planning and Analysis (SC-5)
1000 Independence Ave. S.E.
Washington, D.C. 20585
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