Research On Engineering Prototype Of Transition Radiation Detector For HERD

Supernova,large-scale structure,microwave background radiation,and other observations show that dark matter accounts for 23%of space matter.However,the standard model of particle physics cannot provide suitable dark matter candidate particles,and new physics beyond the standard model itself is required to explain it.The High Energy Cosmic-Radiation Detection（HERD）proposed by our country will operate on the Chinese space station for 10 years.The purpose is to search for signatures of the annihilation/decay products of dark matter particles in the high-energy spectra.To achieve the accuracy of the measurement,HERD proposes to use the transition radiation detector（TRD）to achieve the absolute energy calibration of cosmic ray protons in the Te V energy range.To realize the goal of on-orbit calibration,it is necessary for the detector to have an obvious transition radiation signal,and to meet the target that the on-orbit operating time for more than 5 years.This paper presents a preliminary scheme of a new type of side-on closed transition radiation detector engineering prototype.In order to verify the correctness of the principle,this study first designed a prototype of the side-on transition radiation detector.The performance of the detector such as gain and energy resolution was tested,and the energy calibration of the X-Ray detector based on THGEM was performed using ⁵⁵Fe and high energy electrons.The beam experiment was carried out by the super proton synchrotron of CERN.The detection results of 400 Ge V protons showed that the detection efficiency of the X-Ray detector based on THGEM could be99.8%.In the detection spectrum of the high energy 50 Ge V electron beam,a clear transition radiation signal was seen.Comparing the electron beam results of 20 Ge V,50 Ge V,and 100 Ge V,it is verified that when the Lorentz factor is greater than 10⁴,the radiation is in a saturated state.Using the data processing method of a single electronic channel,the significance of the transition radiation signal can reach 7.35?.Transition radiation detectors have been used in space experiments,but in the past,it was necessary to mount a supplemental gas tank to increase the service life,which caused difficulties for the space mission.To solve the problem of detector life,the preliminary scheme of the engineering prototype adopts the design of the common cavity of the radiator and the X-ray detector to ensure the air-tightness of the TRD.The scheme also reduces the impact of the invalid area on the detection efficiency.The preliminary scheme of the engineering prototype will use a field cage with a wire structure to replace the strip structure in the principle prototype,which can reduce the absorption of radiated photons by the field cage material.The design work of the engineering prototype is initially completed,which can provide a reference for the final scheme of the engineering prototype.