[en] Superconducting RF structures such as spoke resonators (1) have been developed which will accelerate very low velocity ions. This opens up the possibility for the use of these resonators in high power proton accelerators at energies as low as the output energies of typical RFQs. Most similar resonators have been used for the acceleration of ions requiring only low RF power input. In new applications such as for the Accelerator Transmutation of Nuclear Wastes (ATW) and Accelerator Production of Tritium (APT), higher RF power will be required because of the larger beam currents. This paper discusses some higher power variable coupler concepts that could be used with these structures.

No abstract available

[en] Beam dynamics calculations for the Accelerator Production of Tritium (APT) proton linac suggest that wakefields, which are excited during beam operation, would not lead to beam-breakup instabilities. However, in the superconducting (SC) radio-frequency (RF) cavities of the APT linac, higher-order modes (HOMs), whose frequencies are below the beam tube cut-off fiequency, can be sufficiently excited by the beam to add significantly to the heat load removed by the helium refrigerator. In this paper, we present a design of an HOM coupler for the APT RF cavities that will remove this power to a resistive load at room temperature.

[en] In the framework of the TESLA project, the horizontal cryostat (CHECHIA) was built to test a superconducting RF cavity equipped with its helium vessel, magnetic shielding, cold tuner, main coupler and higher order modes couplers under realistic conditions before final assembly of eight cavities into TESLA Test Facility cryo-module. The results of the first cold tests in CHECHIA, performed at DESY with a 9-cell cavity (C19) to be used in the TTF injector are presented. Additional measurements of mechanical stability under RF operation (frequency variation with He pressure, Lorentz detuning) and cryogenic and electric measurements of power dissipation are presented. (author)

[en] Nuclear waste assay is an integral element of programs such as safeguards, waste management, and waste disposal. The majority of nuclear waste is packaged in drums and analyzed by various nondestructive assay (NDA) techniques to identify and quantify the radioactive content. Due to various regulations and the public interest in nuclear issues, the analytical results are required to be of high quality and supported by a rigorous Quality Assurance (QA) program. A valuable QA tool is an intercomparison program in which a known sample is analyzed by a number of different facilities. While transuranic waste (TRU) certified NDA teams are evaluated through the Performance Demonstration Program (PDP), low-level waste (LLW) assay specialists have not been afforded a similar opportunity. NDA specialists from throughout the DOE complex were invited to participate in this voluntary drum assay intercomparison study that was organized and facilitated by the Solid Waste Operations and the Safeguards Science and Technology groups at the Los Alamos National Laboratory and by Eberline Services. Each participating NDA team performed six replicate blind measurements of two 55-gallon drums with relatively low-density matrices (a 19.1 kg shredded paper matrix and a 54.4 kg mixed metal, rubber, paper and plastic matrix). This paper presents the results from this study, with an emphasis on discussing the lessons learned as well as desirable follow up programs for the future. The results will discuss the accuracy and precision of the replicate measurements for each NDA team as well as any issues that arose during the effort

[en] In the framework of the TESLA project, the horizontal cryostat (CHECHIA) was built to test a superconducting RF cavity equipped with its helium vessel, magnetic shielding, cold tuner, main coupler and higher order modes couplers under realistic conditions before final assembly of eight cavities into TESLA Test Facility cryo-module. The results of the first cold tests in CHECHIA, performed at DESY with a 9-cell cavity (C19) to be used in the TTF injector are presented. (author)

[en] The stopping power dE/dX of heavy ions in matter was calculated in terms of the Bethe-Bloch formula and by a phenomenological development of the effective charge. The coefficients of development were obtained by means of the least-square method, and by adjusting the calculated values of the stopping power to the experimental data recently reported in the literature. The stopping power of heavy ions in matter can be calculated using the mean value of this parameters with an accuracy comparable with the Northcliff-Schilling tables. (author)

[en] The quench performance, ramp rate dependence, and mechanical behavior of ten full-length, 50-mm-aperture, SSC dipole magnets built at Fermilab are discussed. Cold testing of these magnets shows that the quench plateau established at 4.35 K exceeds the design value by more than 10%, virtually without training

[en] Three Multiwire Proportional Chambers (MWPC) with high rate capability have been constructed for Fermi National Accelerator Laboratory experiment 705 (Charmonium and Direct Photon production by π/sup +-/, p and /bar p/ at 300 GeV/c). Each chamber, with a sensitive area of 308 cm², consists of three anode planes, wound with 12.5 μm diameter gold-plated tungsten/rhenium wire, facing 25 μm graphite-coated kapton cathode planes at a distance of 3 mm. Wire spacing in two of the MWPC (PC-B1 and PC-B2) is 0.75 mm and 1.00 mm in the third one (PC-B3). After a few weeks of running on ''Magic Gas'' with a beam flux of up to /approximately/10⁷ particles/cm²sec, severe damage occurred to the graphite coating. All cathode planes were replaced by aluminized kapton, and the chambers worked successfully for the next 3 months until the end of the run, when a 10% efficiency drop was observed after a total accumulated charge of /approximately/1 C/cm of sense wire. After the end of the run the chambers were disassembled and inspected. A white deposit with a characteristic ''wire pattern'' etched away from the Al coating was observed in the region of the beam spot. 10 refs., 8 figs., 1 tab

No abstract available