Online measurement of the intensity of keV positron beam

The intensity of keV positron beam generated by 22Na slow positron beam device is weak (generally less than 106 e+/s). Therefore, the traditional method of obtaining beam intensity by Faraday cup is no longer applicable. Currently published methods of obtaining beam intensity are relatively deficient and insufficient. In this paper, a new method was developed to obtain the real-time intensity of positron beam, that is, the HPGe detector was used to collect the 511-keV photons emitted from the thick target bombarded by the positrons, combining with the experimental calibration value of HPGe detector for 511-keV photons as a22Na standard point source placed at the collision point of thick carbon target, and with the relevant parameters got by Monte Carlo simulation. Moreover, the method our group developed and the corrected method of others were both applied for online measurement of beam intensity of 4–9 keV positrons colliding with the pure thick targets (Al, Zn, Nb and Pb). Through comparative analyses, the method our group developed could measure positron beam intensity online more accurately.