Accumulator Ring Design for the European Spallation Source Neutrino Super Beam

University essay from Uppsala universitet/Högenergifysik


In this thesis, the design of a high intensity accumulator ring for the European Spallation Source Neutrino Super Beam (ESSnuSB) is considered. The European Spallation Source (ESS) linear accelerator (Linac), presently being constructed in Lund, Sweden, presents an interesting opportunity to also host an experiment to detect neutrino CP violation. 0.7 ms long H- pulses would be accelerated to 2 GeV and collide with a target, producing pions which then decay into neutrinos. To focus the pions a toroidal magnet (''neutrino horn'') is pulsed with a 350 kA current. The peak current is about 5 μs long, which requires the H- pulses to be shortened to about the same length using an accumulator ring that is located between the linac and the target. The H- would be stripped of their electrons using either a thin carbon foil or a laser beam during injection into the ring. Foil stripping is limited by the lifetime of the foil, which depends on the temperature to which it is heated by the beam. The temperature is simulated in a computer model and the results indicate that it does not rise above the critical temperature (2500 K). The high number of protons (1015) circulating in the ring could cause instabilities due to the collective charge of the particles, known as the space charge effect. The space charge tune shift is calculated for the ESSnuSB and different solutions are discussed. The result of a design accumulator lattice for the ESSnuSB, based on the Spallation Neutron Source, at Oak Ridge National Laboratory, Tennessee, U.S., and made using the computer program Methodical Accelerator Design (MAD), is presented.

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