Beam-Material Interaction

Th is paper is motivated by the growing importance of better understanding of the phenomena and consequences of high- intensity energetic particle beam interactions with accelerator, generic target , and detector components. It reviews the principal physical processes of fast-particle interactions with matter, effects in materials under irradiation, materials response, related to component lifetime and performance, simulation techniques, and methods of mitigating the impact of radiation on the components and envir onment in challenging current and future applicationComment: 28 pages, contribution to the 2014 Joint International Accelerator School: Beam Loss and Accelerator Protection, Newport Beach, CA, USA , 5-14 Nov 201

Summary of working group g: beam material interaction

For the first time, the workshop on High-Intensity and High-Brightness Hadron Beams (HB2010), held at Morschach, Switzerland and organized by the Paul Scherrer Institute, included a Working group dealing with the interaction between beam and material. Due to the high power beams of existing and future facilities, this topic is already of great relevance for such machines and is expected to become even more important in the future. While more specialized workshops related to topics of radiation damage, activation or thermo - mechanical calculations, already exist, HB2010 provided the occasion to discuss the interplay of these topics, focusing on components like targets, beam dumps and collimators, whose reliability are crucial for a user facility. In addition, a broader community of people working on a variety of issues related to the operation of accelerators could be informed and their interest sparked.Comment: 3 pp. 46th ICFA Advanced Beam Dynamics Workshop HB2010, Sep 27 - Oct 1 2010: Morschach, Switzerlan

Towards the optimal energy of the proton driver for a neutrino factory and muon collider

Cross section data from the HARP experiment for pion production by protons from a tantalum target have been convoluted with the acceptance of the front-end channel for the proposed neutrino factory or muon collider and integrated over the full phase space measured by HARP, to determine the beam-energy dependence of the muon yield. This permits a determination of the optimal beam energy for the proton driver for these projects. The cross section data are corrected for the beam-energy dependent amplification due to the development of hadronic showers in a thick target. The conclusion is that, for constant beam power, the yield is maximum for a beam energy of about 7 GeV, but it is within 10% of this maximum for 4<Tbeam < 11 GeV, and within 20% of the maximum for Tbeam as low as 2 GeV. This result is insensitive to which of the two HARP groups' results are used, and to which pion generator is used to compute the thick target effects

Doping of SiC Crystals during Sublimation Growth and Diffusion

The preparation of SiC crystals doped with various impurities introduced during the process of sublimation growth and diffusion is described. The growth of SiC crystals was carried out by a sublimation-sandwich method, proposed by us in 1970. Crystals of the n- and p-type conductivity with maximum content of electrically active impurities (of the order of 1021 cm−3) were obtained. The solubility values of more than 15 impurities were determined. Special tantalum containers with several temperature zones, allowing to introduce any impurity into SiC practically, are developed. The dependences of the impurities concentration on the temperature, growth rate and seed orientation are found. Diffusion of impurities of boron, aluminum, gallium, beryllium, lithium, nitrogen and phosphorus in silicon carbide polytypes was studied. Diffusion coefficients of these impurities in a wide temperature range are determined. It is shown that for a number of impurities diffusion cannot be described by standard distributions that are explained by the presence of several states of diffusing centers. Fast-diffusing states are atoms located in interstices, as well as centers, including the impurity atom and point defect. The extremely low diffusion mobility of lattice point atoms in the SIC lattice is noted