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A large flux of spallation neutrons will be produced at the European Spallation Source (ESS) by impinging high power proton beam on the tungsten target. Until the 5 MW proton beam is stopped by the spallation target, it travels through a number of beam intercepting devices (BIDs), which include the proton beam window, a multi-wire beam profile monitor, an aperture monitor, the beam entrance window, spallation material and the target shroud. The beam-induced thermo-mechanical loads and the damage dose rate in the BIDs are largely determined by the beam energy and the beam current density. At ESS, the proton beam energy will be commissioned step-wisely, from 570 MeV towards 2 GeV. The beam current density on the BIDs in the target station is equally painted by raster beam optics. The ESS Linac and its beam optics will create rectangular beam profiles on the target with varying beam intensities. In this paper, we study the impacts of different plausible beam intensities and beam energies on the thermo-mechanical loads and radiation damage rates in the BIDs at the ESS target station.
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- T. Papaevangelou
CEA/IRFU, Gif-sur-Yvette, France
- H. Alves, S. Aune, J. Beltramelli, Q. Bertrand, T. Bey, B. Bolzon, N. Chauvin, M. Combet, D. Desforge, M. Desmons, Y. Gauthier, E. Giner-Demange, A. Gomes, F. Gougnaud, F. Harrault, F. J. Iguaz Gutierrez, T.J. Joannem, M. Kebbiri, C. Lahonde-Hamdoun, P. Le Bourlout, Ph. Legou, O. Maillard, A. Marcel, C. Marchand, Y. Mariette, J. Marroncle, V. Nadot, M. Oublaid, G. Perreu, O. Piquet, B. Pottin, Y. Sauce, J. Schwindling, L. Segui, F. Senée, R. Touzery, G. Tsiledakis, O. Tuske, D. Uriot
IRFU, CEA, University Paris-Saclay, Gif-sur-Yvette, France
- I. Dolenc Kittelmann, R.J. Hall-Wilton, C. Höglund, L. Robinson, T.J. Shea, P. Svensson
ESS, Lund, Sweden
- V. Gressier
IRSN, Saint-Paul-Lez-Durance, France
- K. Nikolopoulos
Birmingham University, Birmingham, United Kingdom
- M. Pomorski
CEA/DRT/LIST, Gif-sur-Yvette Cedex, France
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A new type of Beam Loss Monitor (BLM) system is being developed for use in the European Spallation Source (ESS) linac, primarily aiming to cover the low energy part (proton energies between 3-100 MeV). In this region of the linac, typical BLM detectors based on charged particle detection (i.e. Ionization Cham-bers) are not appropriate because the expected particle fields will be dominated by neutrons and photons. Another issue is the photon background due to the RF cavities, which is mainly due to field emission from the electrons from the cavity walls, resulting in brems-strahlung photons. The idea for the ESS neutron sensi-tive BLM system (ESS nBLM) is to use Micromegas detectors specially designed to be sensitive to fast neutrons and insensitive to low energy photons (X and gammas). In addition, the detectors must be insensitive to thermal neutrons, because those neutrons may not be directly correlated to beam losses. The appropriate configuration of the Micromegas operating conditions will allow excellent timing, intrinsic photon back-ground suppression and individual neutron counting, extending thus the dynamic range to very low particle fluxes.
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