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HIGH ENERGY PHYSICS

The long-standing goal of the High Energy Physics program is to improve our understanding of the nature of matter and energy and of the basic forces that govern the world in which we live. One of the major objectives of high energy physics research is to develop a unified description, or single theory, that would describe all the interactions of matter and energy in the universe. Another major objective is to search for the most fundamental constituents of matter. To continue to expand our knowledge in these areas, the program must develop advanced technologies that are used in the accelerators and detectors required to carry out high energy physics research.

Over the years, the program has contributed significantly to the development

of advanced technology in many areas critical to the United States' economy,

such as large-scale computing, high-speed electronics, and low temperature superconductivity. The instruments of high energy physics research and the knowledge gained from this basic research program have found practical

applications in our every day world: in medicine for diagnosis and treatment

of illness, in the food industry for sterilization, in construction for inspection of structural defects, in law enforcement for the analysis of evidence, in computers and computer science, and in the making of computer

chips.

In recent years, high energy physicists have developed an increasingly better understanding of the forces of nature and the unifying connections among them. The four known fundamental forces are the electromagnetic force, the weak

force, the strong force, and the gravitational force. The search for a unified, or single, theory has been a reliable guide to physics research. It is a search for linkages between apparently diverse phenomena in an effort to discover underlying simplicity. A part of the progress in high energy physics has been the conceptual unification of the weak nuclear force and electromagnetic force into a single "electroweak" framework. In addition, a theory of the strong force has emerged which is consistent with experimental results. There is increasing anticipation that the unification of the strong nuclear and the electroweak forces into one "grand unified" framework may be possible, thus reducing the apparent number of forces in nature to two. The ultimate goal is a "super-grand" unification that would bring all of the forces in nature into a single unified framework.

This picture of nature in terms of the electroweak and strong forces and a small set of fundamental constituents of all matter is known as the Standard Model. While the most significant recent experimental results all reinforce the predictions of the Standard Model, there are still unanswered fundamental questions. For instance, have we discovered the ultimate constituents of matter or are there smaller particles inside the families of particles called "leptons" and "quarks" which we currently believe are the fundamental particles? Do we know all the forces of nature? Are all these forces only a manifestation of a single force? How does gravity fit into the Standard

Model?

The ability to carry out forefront, exploratory research in High Energy
Physics, and to pursue the answers to these questions, requires large particle
accelerators, colliding beam devices, and large particle detectors. In the
U.S., DOE supports three accelerator centers: the Fermi National Accelerator
Laboratory (Fermilab), the Stanford Linear Accelerator Center (SLAC), and the
Alternating Gradient Synchrotron (AGS) at Brookhaven National Laboratory

(BNL). Each of these laboratories provides world-unique capabilities and is

operated as a national facility available to qualified experimenters from

around the world on the basis of the scientific merits of their proposals.

The talented physicists attracted by these facilities have continued to conduct landmark research, some of it earning Nobel Prizes for the researchers. To push back the frontiers to new knowledge in this field and to

maintain this pioneering program into the next century, construction of the

Superconducting Super Collider (SSC) is necessary.

The SSC, which will be

discussed later in this statement, will be the largest scientific instrument ever built and will be a beacon for new discovery, scientific training for our youth, and a source of new technology for many decades.

The physicists who are planning and developing experiments to be conducted at

the SSC will continue to be funded under the High Energy Physics program as has been the past practice for other accelerators. Similarly, most of those who will conduct research at the SSC will come from the university community, as is the case at the existing accelerators. More than 75 percent of the research done at V.S. High Energy Physics accelerator facilities is carried out by university-based scientists and graduate students. Their participation is critical to the strength and vitality of the U.S. program, both in the production of research results and in the training not only of new physicists, but also of scientists and engineers in other disciplines.

Before turning to a discussion of the FY 1991 budget request, I would like to summarize some of the recent progress made by the university and laboratory scientists working at the three High Energy Physics accelerator facilities. The capabilities of the Tevatron at Fermilab allow scientists to observe a larger number of particle interactions than at any other facility in the world. Scientists there are searching for an as yet unobserved, but theorized, particle known as the "top quark" whose existence, if verified, would confirm predictions of the Standard Model. Based on analysis of the results of experiments run in 1989, Fermilab investigators have shown that the mass of the top quark must be greater than 78 billion electron volts (GeV). Thus, the search must continue through experiments at even higher energies which are available only at the Tevatron.

At SLAC, the recently completed Stanford Linear Collider (SLC) has demonstrated the concept of linear colliders. Using 50 GeV beams, SLC is providing crucial data on the feasibility of building a next generation of higher energy linear colliders to permit experimentation in a new energy region. The second goal of the SLC is to study the so-called 2° particle, believed to be the "carrier" of the weak nuclear force. Detailed study of this particle provides important tests of the Standard Model including a direct measurement of the number of generations of neutrinos, which are uncharged elementary particles. Thus far, scientists at the SLC have detected more than 500 Zo particles at 7 energy levels. Using these particles, scientists made the first precise measurement of the width and mass of the Zo

and have determined with a high degree of probability that, in conformance with the Standard Model, there are three generations of neutrinos.

At Brookhaven National Laboratory, the Alternating Gradient Synchrotron's (AGS) extensive facilities provide yet another different test of the Standard Model by studying the way (or mode) in which particles called "kaons" decay. Some of these decay modes occur very infrequently and thus are called rare decay modes. Using improved detectors, recent physics results have reduced the upper limits on the rates of decay for these rare decay modes to as low as one in three billion ordinary decays. The Standard Model predicts that these rare decays will occur at a rate lower than one in three billion. Ongoing studies will continue to provide experimental results for comparison with the predictions of the Standard Model.

FY 1991 HIGH ENERGY PHYSICS BUDGET REQUEST

The FY 1991 budget request for High Energy Physics is $621.2 million. Of the total amount, $494.2 million is for Operating Expenses, $88.2 million is for Capital Equipment, and $38.8 million is for Construction. (Tables 2 and 3).

The Operating Expenses request of $494.2 million provides for the continued participation of both experimental and theoretical university scientists and students who are critical to the success of the High Energy Physics program, as well as for the operation of the High Energy Physics accelerators: the Stanford Linear Collider, the Tevatron accelerator/collider, and the AGs. The Tevatron will conclude a major fixed target run which will be followed

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