关键词: 带电粒子活化/
激光质子加速/
符合测量/
解谱
English Abstract
Charged paricle activation analysis for characterizing parameters of laser-accelerated protons
He Shu-Kai1,Liu Dong-Xiao1,
Jiao Jin-Long1,
Deng Zhi-Gang1,
Teng Jian1,
Zhang Zhi-Meng1,
Hong Wei1,
Gu Yu-Qiu1,
1.Key Laboratory of Plasma Physics, Laser Fusion Research Center, China Academy of Engineering Physics, Mianyang 621900, China;
2.International Fusion Sciences and Applications(IFSA) Collaborative Innovation Center, Shanghai Jiao Tong University, Shanghai 200240, China;
3.Center for Applied Physics and Technology, Peking University, Beijing 100871, China
Fund Project:Project supported by the Science and Technology Development Foundation of China Academy of Engineering Physics (Grant No. 2013A0103003) and the Major Special Scientific Instruments and Equipment Development of Ministry of Science and Technology, China (Grant No. 2012YQ03014206).Received Date:08 May 2017
Accepted Date:18 July 2017
Published Online:05 October 2017
Abstract:The protons accelerated by ultra-high intensity laser have been extensively studied. The most commonly used detectors for measuring laser-driven proton are Tomspon parabola ion energy analyser (TP) and filtered nuclear track detectors, such as radiochromic films (RCF). The TP uses a parallel magneto-electric field to distinguish ions. This conventional technique can precisely identify the species and energy spectra of ions. However, the strong electromagnetic field produced by the laser-plasma interaction has an effect on TP, which results in no spatial resolution of TP. The RCF can give the spatial integration spectrum of proton, but it is easy to be saturated and cannot be reused anymore. In this paper, we present a method based on the traditional charged particle activation analysis and the gamma-gamma coincidence measurement to measure the spectrum of protons accelerated by ultra intense lasers. In this method, a copper plate stack is placed in the proton emission direction. Colliding with MeV proton converts 63Cu in the copper plates into radionuclide 63Zn whose decay can be easily observed and measured. Proton spectrum is then recovered from 63Zn decay counts from layers in the copper stack. The layout of diagnostics and the method to solve proton spectrum are discussed in detail and a self-consistent test is given. This spectrum analysis method is used in a laser-driven proton acceleration experiment carried out on XG-Ⅲ laser facility. The results show that protons up to 18 MeV are obtained, and the spatial integrated spectrum and a laser-proton conversion efficiency of 1.07% are achieved. In conclusion, our method has some advantages as a laser-driven ion diagnostic tool. It has no saturation problem and is not affected by strong electromagnetic fields. The basic principle of charged particle activation analysis is based on nuclear reaction, and can be extended to the measuring of other charged particle beams besides protons, such as deuterons, helium ions produced by ultra-high intensity laser.
Keywords: charged particle activation analysis/
laser-driven proton acceleration/
coincidence measurement/
unfold spectrum
