Two-loop self-dual Euler-Heisenberg Lagrangians (II): Imaginary part and Borel analysis

We analyze the structure of the imaginary part of the two-loop Euler-Heisenberg QED effective Lagrangian for a constant self-dual background. The novel feature of the two-loop result, compared to one-loop, is that the prefactor of each exponential (instanton) term in the imaginary part has itself an asymptotic expansion. We also perform a high-precision test of Borel summation techniques applied to the weak-field expansion, and find that the Borel dispersion relations reproduce the full prefactor of the leading imaginary contribution.Comment: 28 pp, 6 eps figure

The laser switched linac and development of a high brilliance electron source

This task originated in 1987 to explore the possibility of accelerating short bursts of electrons by pulsed power. The principal effort of our group was to demonstrate that electrons can be accelerated by picosecond-long electrical pulses which are compressed in a radial transmission line. This goal has new been achieved and our results are presented in this paper. We have achieved a gradient of 45 MV/m across a 250 {mu}m accelerating gap and have accelerated 10{sup 6} electrons in a 1 ps long pulse. The beam emerges from a 500 {mu}m hole and can be refocused to this transverse dimension. The efficiency of the system, is of order {eta} = 2 {times} 10{sup {minus}6} due to the small number of electrons accelerated. If we identify the gap spacing with one half wavelength of the accelerating r.f.,''our device is equivalent to a 600 GHz structure. The principal limitation in the accelerating gradient comes from the H.V. hold-off properties of the semiconductor disks that are used as photoconductive switches. We believe that with better materials a factor of 10 can be gained in the gradient. Similarly, the electron yield can be increased by at least three orders of magnitude if proper photocathodes are used in place of the metallic surface. The more difficult problem is the engineering of a multicell structure using our present design of the single cell. Our plans for the continuation of this work are given. One of the most promising applications of laser switched acceleration is in the operation of a very low emittance electron source. Thus we have turned our attention to this subject, and in particular to building a high brilliance electron source using a superconducting cavity. Also discussed is the possibility of picosecond x-ray sources

Search for anomalous gravitational effects at the Fermilab accelerator. Progress report on E-723

This is a progress report on the results of tests of a gravitational detector operated in the CO area of the Fermilab accelerator in June and July of this year. Our experience so far is that these measurements are feasible and we have set a limit on the ratio of the coupling of a long range to that of the gravitational constant of g/G < 3x10/sup 20/. The sensitivity of the experiment is evaluated to be 0.5x10/sup 6/ times lower than for the test-run and should be achieved during the forthcoming fixed target operating period

Measurement of the Magnetic Birefringence of Neon Gas

11nonenoneR. CAMERON; CANTATORE G.; H.J. HALAMA; D. LAZARUS; A.C. MELISSINOS; P. MICOSSI; A.G. PRODELL; C. RIZZO; G. RUOSO; Y.K. SEMERTZIDIS; E. ZAVATTINIR., Cameron; Cantatore, Giovanni; H. J., Halama; D., Lazarus; A. C., Melissinos; P., Micossi; A. G., Prodell; C., Rizzo; G., Ruoso; Y. K., Semertzidis; E., Zavattin

Theoretical and experimental studies of elementary physics

The experimental high energy physics program is directed toward the execution of experiments that probe the basic constituents of matter and the forces between them. These experiments are carried out at national and international accelerator facilities. At the current time, we are primarily concentrating on the following projects: Direct photon production in hadronic reactions (Fermilab E706); Production of hybrid mesons in the nuclear Coulomb field; The D-Zero experiment at the Tevatron collider; Deep inelastic neutrino- and electron-nucleon scattering at FNAL and SLAC; Nonlinear QED at critical field strengths at SLAC; The Experiments at KEK (AMY, 17keV neutrino); The CDF experiment at the Tevatron collider; and SSC-related detector R D on scintillating tile- and diamond-based calorimetry and microstrip tracking detectors