Measurements Of Proton Beam Flux And Energy Of APEP Using Foil Activation Technique

The proton beam flux and energy are crucial parameters for proton irradiation facilities.Accurate measurement of these parameters greatly impacts the precision of activation experiments,nuclear data measurements,and radiation-resistant tests on electronic devices.The Associated Proton beam Experiment Platform（APEP）is a new proton radiation facility at the China Spallation Neutron Source（CSNS）.However,some of the beam monitoring equipment is not fully equipped for online monitoring.Under experimental conditions that involve long irradiation times,long cooling times,a wide range of proton fluxes,and a Gaussian-like proton energy spectrum with energy spreads ranging from a few percent to tens of percent,the activation technique was employed to measure the proton flux and energy.1)In this study,the proton beam flux of APEP under different beam spot sizes was accurately measured using the activation method.The reactions of ^natTi（p,x）⁴⁸V,^natNi（p,x）⁵⁷Ni,^natCu（p,x）⁵⁸Co,and ²⁷Al（p,x）²⁴Na were selected based on considerations of factors such as activation foil materials,sizes,and half-lives of reaction products.The proton beam flux was measured at seven nominal proton energies ranging from 10 Me V to 70 Me V for beam spot sizes of 20 mm×20 mm and 50 mm×50 mm.The experiments showed that the APEP proton flux ranges from 10⁷-10⁹ p/cm²/s.2)This study proposed a new method using the activity ratio with a stacked-foil target with two or three layers to determine the Gaussian-like proton energy spread for different nominal proton energies.The optimal combinations of Al,Cu,Ti,Ni,Mo,Fe,Nb and In foils was adopted for the proton energies.For a measurement of proton beam energy,three specific reaction processes are chosen from two or three activation foils.By measuring the activity of certain radionuclides of these activation foils,the center energy E₀ and Gaussian energy distribution widthσg can be numerically determined.the measurement results show that the energy between 30 Me V and 80 Me V is less than 10.00%,whereas the energy spread in the range of 10-20 Me V is larger.In summary,this study provides key beam parameters for irradiation experiments at APEP by investigating the practical application of the activation technique in the field of proton beam parameter measurement.The developed method using stacked-foil target for measuring the energy and energy spread for a Gaussian-like proton beam can be applicable for similar proton irradiation facilities.