Energy spectrum measurement of protons below 100 keV in laser acceleration using CR-39 solid track detector

It was proved by experiments that CR-39 solid track detector can't detect protons below 100 keV because of its critical angle in the paper. Hereby, the detection arrangement was improved. The proton energy spectrum below 100 keV was measured by CR-39 solid track detector and Thomson spectrometer in the experiment of laser interaction with 5 μm Al foil. Single particle simulation was used to process data from the magnetic spectrometer, which can avoid the error from fringe magnetic field in spectrometer and improve the precision.