Plasmas offer the possibility of high acceleration gradients. An intriguing possibility is using the higher plasma densities possible in solids to get extremely high accelerating gradients. Although solid state plasmas might produce high gradients they would face daunting problems. Crystal channeling has been suggested as one mechanism to address these problems. There is no experimental or theoretical guidance on channeling in very intense electron and laser beams. A very high density plasma in the crystal lattice could quench the channeling process. An experiment is currently under way at the A0 PhotoInjector Test Facility at Fermilab to investigate the upper intensity limit for the production of channeling radiation for electrons interacting with thin Si and diamond crystals. An electron beam with up to 10 nC per electron bunch of 10 ps pulse length will permit investigations of the electron-crystal interaction at charge densities several orders of magnitude larger than observed so far and see if the channeling signal quenches as the bunch charge is increased . The photon flux predicted at these experimental conditions results in 3 x 10 9 photons/sr pulse at a photon energy between 15 and 25 keV. An X-ray camera based on a CCD coupled scintillator-screen device has been specially developed to handle the predicted high photon rates. Later stages of the experiment may attempt solid-state plasma acceleration possibly by looking at head-to-tail effects due to the excitation of plasma wakes. *Operated by Universities Research Association, Inc. under contract No. DE-AC0276CHO3000 with the United States Department of Energy **Supported by BMBF contract number 06DA820

A photoinjector is being constructed in order to produce a pulse train of up to 800 electron bunches, each with 8 nC of charge and a 3.5 ps rms bunch length. The spacing between bunches within a train is 1 s and the train repe- tition rate is 1-10 Hz. The desired transverse emittance is 20 mm mrad. An rf photo-gun delivers a bunched 4-5 MeV beam which will be accelerated to 14-18 MeV by a 9- cell superconducting cavity and compressed magnetically. Measurements have been done on the beam delivered by a first prototype rf gun; installation of a new rf gun, the 9-cell cavity, and the bunch compressor is in progress.

Similar to the power leads of accelerator superconducting magnets, the power couplers of accelerator superconducting cavities are components that link room temperature to superfluid helium temperature for the purpose of energy transfer. Instead of conducting kiloamperes of current they guide megawatts of RF power between those two temperatures. In this paper we describe a cryostat designed for testing the performance of these components and measuring their heat loads. A special feature of this cryostat is its minimum liquid inventory that considerably simplifies safety related requirements. This cryostat is part of a Fermilab facility contributing to the international collaboration working on TESLA (TeV Electron Superconducting Linear Accelerator). This facility is now operational and we will be presenting specifications as well as performance data on the cryostat as well as the first pair of power couplers tested with it.

The Tevatron low- beta lattice that allows operation of two independent low- beta insertions is described. The measurement of the beta functions at various locations near the interaction region of the B0 and comparisons to theoretical calculations are reported.< >

A new low β insertion has been designed for the B0 and D0 straight sections of the Tevatron Collider. Each low β insertion consists of 18 superconducting quadrupoles which are powered independently of the Tevatron accelerator magnets to focus the beams at the interaction region. The authors describe the quench behavior of the low β quadrupoles, their power circuits, and their quench protection systems

The Fermilab design of a 5 T, 5 cm aperture superconducting dipole is described, that attempts to integrate essential cryogenic details with a low cold mass, low heat leak magnet containing a coil surrounded by aluminum collars. Operating characteristics of coils made with aluminum collars are presented along with harmonic data obtained from 1 meter long 5 cm aperture collared coils. A summary of results obtained from cold tests of a 7.6 cm aperture, 6 m long aluminum collared coil in an iron vacuum vessel cryostat are reviewed. Results from the measurement of heat leak to 4.5K, 10K, and 80K are discussed for a 12 m prototype cryostat. Calculations are summarized for passively correcting the persistent current sextupole fields.

The construction and operation details of a local absorbed dose microcalorimeter are presented. This calorimeter measures the absorbed dose rate at any desired point within an irradiated medium. The measurement is specific to a sufficiently limited region (2.0 cm in dia, 0.3 cm deep) that the measurement is essentially at a point and no integration or averaging process is necessary to qualify either the absorbed dose, or its rate. The system is sufficiently sensitive to provide about 1% accuracy at dose rates of 50 rads/min. The application of this calorimeter to 10-Mev and 20-Mev incident electrons is described. The use of a secondary standard (Victoreen 25-r chamber) under specified conditions is given together with details of calibration for use with high-energy electrons. The influence of the polarization effect was noted. The Fricke ferrous sulfate dosirieter was also calibrated for these energies of electrons. Samples of dosimeter solution were exposed in a geometry identical with that of the small sensitive region of the calorimeter. A value of G/sub Fe// sup 3+/ of 15.32 plus or minus 0.34 was obtained for 10-Mev electrons, and a value of 15.17 plus or minus 0.28 for 20-Mev electrons. (auth)