LAL, Orsay, France
UA9 was operated in the CERN-SPS for more than two years in view of investigating the feasibility of the halo collimation with bent crystals. Silicon crystals 2 mm long with bending angles of about 150 urad were used as primary collimators. The crystal collimation process was steadily achieved through channeling with high efficiency. The crystal orientation was easily set and optimized with the installed goniometer which has an angular reproducibility of about ± 10 μrad. In channeling orientation, the loss rate of the halo particles interacting with the crystal is reduced by a factor of ten, whilst the residual off-momentum halo escaping from the crystal-collimator area is reduced by a factor five. The crystal channeling efficiency of about 75 % is reasonably consistent with simulations and with single pass data collected in the North Area of the SPS. The accumulated observations, shown in this paper, support our expectation that the coherent deflection of the beam halo by a bent crystal should considerably help in enhancing the collimation efficiency in LHC.
IAP, Frankfurt am Main, Germany
GSI, Darmstadt, Germany
Intense ion beams with small phase space occupation (high brilliance) are mandatory to keep beam losses low in high current injector accelerators like those planned for FAIR. The low energy beam transport from the ion source towards the linac has to keep the emittance growth low and has to support the optimization of the ion source tune. The Frankfurt Neutron Source Facility FRANZ is currently under construction. An intense beam of protons (2 MeV, 200 mA) will be used for neutron production using the Li7(p,n)Be7 reaction for studies of the astrophysical s-process. A collimation channel, which can be adjusted to allow the transport of beams with a certain beam emittance, is an ideal tool to optimize the ion source tune in terms of beam brightness. Therefore a collimation channel in the Low Energy Beam Transport section will be used. Through defined apertures and transversal phase space rotation using focusing solenoids the beam halo as well as unwanted H2+ and H3+ fractions will be cut. Theoretical studies which were carried out so far and a first design of the setup will be presented.
CIEMAT, Madrid, Spain
The IFMIF/EVEDA linear accelerator is a 9 MeV, D+ prototype for the validation of the 40 MeV final IFMIF design. The high intensity, 125 mA CW, high power beam (1.125 MW) produces an extremely high thermal load in all the elements intercepting the ions. Independently of the final purpose of each device, if its working conditions imply stopping a non-negligible amount of particles, the associated thermal solicitation greatly determines the design constraints. The present work will summarize a thermo-mechanical design workflow that can be applied to any beam facing element of high current accelerators and its application in beam dump, scrappers and slits design. This approach is based on analysis experiences at the IFMIF/EVEDA project and, while taking into account the particularities of each device, uses the same tools and parameter evaluation criteria for all of them. It has been applied successfully to recent designs, effectively reducing the number of iterations before achieving a valid thermo-mechanical behavior. Results of each design and the concrete advantages of this approach will be detailed.