Source of slow polarized positrons using the brilliant gamma beam at ELI-NP. Converter design and simulations
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- 作者：Nikolay Djourelov ; nikolay.djourelov@eli-np.ro" class="auth_mail" title="E-mail the corresponding author ; Andreea Oprisa ; Victor Leca
- 关键词：Gamma beam ; Slow positron beam ; Polarized positrons ; Simulation
- 刊名：Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment
- 出版年：2016
- 出版时间：11 January 2016
- 年：2016
- 卷：806
- 期：Complete
- 页码：146-153
- 全文大小：4882 K
文摘
Simulations of slow positron (
) source based on interaction of a circularly polarized gamma beam with a W converter were performed. The aim of the study was to propose a converter geometry and to determine the expected slow positron beam intensity and its spot size, and the degree of positron spin polarization, as well. The Monte Carlo simulations by means of GEANT4 were used to estimate the fast positron production and the moderation efficiency of the converter working as a self-moderator, as well. Finite element analysis by means of COMSOL Multiphysics was applied to calculate the fraction of extracted moderated positrons from the converter cells and the quality of the beam formation by focusing. Using the low energy (<3.5 MeV) gamma beam at ELI-NP with intensity of 2.4×1010γ/s the production of a slow positron beam with intensity of 1–2×106/s is predicted. For the optimized converter geometry and in case of 100% circular polarization of the gammas the degree of spin polarization of the slow positron beam is expected to be 33%.
) source based on interaction of a circularly polarized gamma beam with a W converter were performed. The aim of the study was to propose a converter geometry and to determine the expected slow positron beam intensity and its spot size, and the degree of positron spin polarization, as well. The Monte Carlo simulations by means of GEANT4 were used to estimate the fast positron production and the moderation efficiency of the converter working as a self-moderator, as well. Finite element analysis by means of COMSOL Multiphysics was applied to calculate the fraction of extracted moderated positrons from the converter cells and the quality of the beam formation by focusing. Using the low energy (<3.5 MeV) gamma beam at ELI-NP with intensity of 2.4×1010γ/s the production of a slow positron beam with intensity of 1–2×106/s is predicted. For the optimized converter geometry and in case of 100% circular polarization of the gammas the degree of spin polarization of the slow positron beam is expected to be 33%.