Design of a pulsed positron system at Trombay

[摘要] We present here the design of a pulsed beam setup to deliver narrow time width positron pulses. The major constituents of the setup include-22Na radioactive source and moderator assembly, ExB deflector for filtering out high energy positron and gamma rays, chopper-prebuncher-buncher assembly for time bunching of the slow positrons. In the ExB section, crossed electric and magnetic fields guide the slow positrons through an off-centered hole in a tungsten block. The initial beam will then be time bunched by using a reflection type chopper and a double gap prebuncher. The main buncheris designed as a quarter wave resonator with base frequency of 150 MHz.To prevent the sagging of the cantilevered inner tube of the resonator, we will support the inner conductor using an alumina post. There will be provision of tuning the frequency by using a tuner made of conducting material. The incident beam energy will be varied by biasing the sample.

[发布机构] Radiochemistry Division, Bhabha Atomic Research Centre, Mumbai; 400085, India^1;Ion Accelerator Development Division, Bhabha Atomic Research Centre, Mumbai; 400085, India^2

[效力级别] 化学

[关键词] Base frequencies;Conducting materials;Crossed electric and magnetic fields;Incident beam energy;Quarter wave resonators;Radioactive sources;Reflection type;Slow positron