No abstract

An interceptive device referred to here as a scraper has been designed and tested for use in a diagnostic device [1]. The scraper will be used to probe a proton beam in order to detect the formation of beam halo [2]. Probing the proton beam exposes the scraper to high heat fluxes on the order of 610 kW/cm 2 . The high-heat flux exposure is cyclic since the beam is probed while in pulsed mode. In order to test the design repetitive high-heat flux testing has been performed on a prototype design of the scraper. This paper describes the design, analysis, and testing of the scraper.

Within the framework of the Advanced Accelerator Applications (AAA) project we are interested in building and testing low-β spoke resonators (cavities). To familiarize us with the specifics of these structures Argonne National Laboratory (ANL) kindly loaned us one of their spoke cavities for evaluation. This is a β=0.291 2-gap resonator at 340 MHz. We benchmarked our computer codes by comparing room temperature measurements of frequency, tuning sensitivity, tuning forces, etc. with our 3D simulation results. The cavity was tested at both 4 K and 2 K. The results showed maximum accelerating gradients of 12.5 MV/m (4 K) and 12.3 MV/m (2 K), which correspond to a peak electric field of 40 MV/m and a peak magnetic field of 1063 Oe. Q 0 values at 5 MV/m also exceeded by more than a factor 2 of present AAA specification. These results encouraged us toward development of spoke cavities for the low energy section (6.7 MeV to 109 MeV) of ADTF (Accelerator-Driven Test Facility) of AAA project.

Flat panel imagers based on amorphous silicon technology (a-Si) for digital radiography are accepted by the medical and industrial community as having several advantages over radiographic film-based systems. Use of Mega-voltage x-rays with these flat panel systems is applicable to both portal imaging for radiotherapy and for nondestructive testing (NDT) and security applications. In the medical field, one potential application that has not been greatly explored is to radiotherapy treatment planning. Currently, such conventional computed tomographic (CT) data acquired at kV energies is used to help delineate tumor targets and normal structures that are to be spared during treatment. CT number accuracy is crucial for radiotherapy dose calculations. Conventional CT scanners operating at kV X-ray energies typically exhibit significant image reconstruction artifacts in the presence of metal implants in human body. Using the X-ray treatment beams, having energies typically ≥6MV, to acquire the CT data may not be practical if it is desired to maintain contrast sensitivity at a sufficiently low dose. Nondestructive testing imaging systems can expand their application space with the development of the higher energy accelerator for use in pipeline, and casting inspection as well as certain cargo screening applications that require more penetration. A new prototype x-band BCL designed to operate up to 1.75 MV has been designed built and tested. The BCL was tested with a prototype portal imager and medical phantoms to determine artifact reductions and a PaxScan 2530HE industrial imager to demonstrate resolution is maintained and penetration is improved.

The Accelerator Driven Test Facility (ADTF) is being developed as a reactor concepts test bed for transmutation of nuclear waste. A 13.3 mA continuous-wave (CW) proton beam will be accelerated to 600 MeV and impinged on a spallation target. The subsequent neutron shower is used to create a nuclear reaction within a subcritical assembly of waste material that reduces the waste half-life from the order of 10 5 years to 10 2 years. Additionally, significant energy is produced that can be used to generate electrical power.The ADTF proton accelerator consists of room-temperature (RT) structures that accelerate the beam to 6.7-MeV and superconducting (SC) elements that boost the beam's energy to 600-MeV. Traditional SC elliptical cavities experience structural difficulties at low energies due to their geometry. Therefore, stiff-structured SC spoke cavities have been adopted for the energy range between 6.7 and 109 MeV. Elliptical cavities are used at the higher energies. This paper describes a multi-spoke-cavity cryomodule concept for ADTF.