Limiting technologies for particle beams and high energy physics

Since 1930 the energy of accelerators had grown by an order of magnitude roughly every 7 years. Like all exponential growths, be they human population, the size of computers, or anything else, this eventually will have to come to an end. When will this happen to the growth of the energy of particle accelerators and colliders. Fortunately, as the energy of accelerators has grown the cost per unit energy has decreased almost as fast as has the increase in energy. The result is that while the energy has increased so dramatically the cost per new installation has increased only by roughly an order of magnitude since the 1930's (corrected for inflation), while the number of accelerators operating at the frontier of the field has shrunk. As is shown in the by now familiar Livingston chart this dramatic decrease in cost has been achieved largely by a succession of new technologies, in addition to the more moderate gains in efficiency due to improved design, economies of scale, etc. We are therefore facing two questions: (1) Is there good reason scientifically to maintain the exponential growth, and (2) Are there new technologies in sight which promise continued decreases in unit costs. The answer to the first question is definitely yes; the answer to the second question is maybe

Propagation and Structure of Planar Streamer Fronts

Streamers often constitute the first stage of dielectric breakdown in strong electric fields: a nonlinear ionization wave transforms a non-ionized medium into a weakly ionized nonequilibrium plasma. New understanding of this old phenomenon can be gained through modern concepts of (interfacial) pattern formation. As a first step towards an effective interface description, we determine the front width, solve the selection problem for planar fronts and calculate their properties. Our results are in good agreement with many features of recent three-dimensional numerical simulations. In the present long paper, you find the physics of the model and the interfacial approach further explained. As a first ingredient of this approach, we here analyze planar fronts, their profile and velocity. We encounter a selection problem, recall some knowledge about such problems and apply it to planar streamer fronts. We make analytical predictions on the selected front profile and velocity and confirm them numerically. (abbreviated abstract)Comment: 23 pages, revtex, 14 ps file

Spin motion of electrons in the SLC linac

It is generally expected that the depolarizing effects of the linear accelerator RF fields will be small. Recently Bill Atwood raised the question whether this conclusion is still correct in view of the fact that the particles in the SLC spend a larger fraction of their time at phase angles off crest'' due to BNS damping; since radial fields are in quadrature with the accelerating field this might imply that depolarizing effects are larger. On the other hand, because of the smaller emittance of the SLC relative to the earlier linac radial excursions would be smaller. The anticipation is therefore that the depolarizing effect will again be negligible but it might be worthwhile to update the early calculations of SLAC TN-63-97 revised. This paper discusses these updates

What can we expect from future accelerators

This talk covers a general but highly subjective overview of the expectation for new accelerator development. An updated version of the Livingston chart demonstrates the exponential growth in time of the equivalent laboratory energy of accelerators. A similar Livingston chart pertaining only to electron-positron colliders shows an exponential growth but in the past only one technology - electron-positron storage rings - have been responsible for this development. The question addressed is whether the type of exponential growth reflected by these two charts can be sustained in the future

Future of high energy physics

A rough overview is given of the expectations for the extension of high energy colliders and accelerators into the xtremely high energy range. It appears likely that the SSC or something like it will be the last gasp of the conventional method of producing high energy proton-proton collisions using synchrotron rings with superconducting magnets. It is likely that LEP will be the highest energy e+e/sup -/ colliding beam storage ring built. The future beyond that depends on the successful demonstrations of new technologies. The linear collider offers hope in this respect for some extension in energy for electrons, and maybe even for protons, but is too early to judge whether, by how much, or when such an extension will indeed take place

Concluding talk-seminar on critical issues in development of new linear colliders

The growth of particle colliders is summarized, with their collision energy in the frame of the elementary constituents given for numerous specific machines. The logic concerning the design of electron-positron colliders and definition of parameters are briefly discussed. Several issues are covered which are presently uncertain, including beamstrahlung and interaction among beams of transverse dimensions in the angstrom range. Alternate power sources and their economy are considered as well as superconducting structures. (LEW

What does a beam position monitor monitor

Beam position monitors have been used progressively at SLAC requiring higher and higher accuracy. The assumption is always made that a beam position monitor measures the position of the bunch at the geometrical center between the electrodes at the time of passage of the bunch. There is no experimental evidence either with beams or with wires carrying current pulses that this assumption is incorrect. Yet as energies increase and as the required accuracy moves into the micron range it appears useful to look at this fundamental assumption

Progress report on future accelerators

SLAC intends to pursue high energy physics work in the future along three lines: (1) continued exploration of electron and photon physics on stationary targets; (2) colliding beam physics using electron-positron storage rings; (3) single-pass collider physics with electrons using first the Stanford Linear Collider (SLC) and eventually a single-pass collider operating near the highest practical upper limit for such devices. These long-range plans are discussed