Development Of A Start-time Detector For External Target Facility

As the key detector for time-of-flight resolution at the External Target Facility(ETF),the performance of the start-time detector will directly affect the results of particle identification,which plays an important role in the research of unstable nuclear at ETF.The original start-time detector adopts a scheme which selects plastic scintillator as detection medium and photomultiplier as readout device.In combination with the current and future operation of ETF,the start-time detector needs to be improved.In this paper,a new design scheme of the start-time detector is proposed,and the development and performance test of the prototype of start-time detector are carried out.First,the paper tests the performance of the detector's photoelectric readout devicesilicon photomultiplier(SiPM),including the I-V curve,linear,single photon resolution,gain,the performance parameters of the SiPM are determined,and SensL MicroFC-30035 is finally selected as the photoelectric readout device of the new prototype of start-time detector.Then the performance of the plastic scintillating fiber is measured.Kuraray SCSF-78 J is used,and the core layer attenuation length is 547.5cm,the cladding layer attenuation length is 15.5cm,the light yield is approximately 552 photons/mm.The propagation of light in the fiber is about 17cm/ns,the time resolution of fiber is better than 600 ps,and the corresponding position resolution is better than 7.2cm.Next,the new start-time detector is designed and developed,which include the construction of the start-time detector and the confirmation of the scheme for reading electronics and so on.Finally,the prototype of start-time detector is tested in the beam experiment,by optimizing its multiplicity and time-amplitude correction,the time resolution of the detector in beam test is(150±15)ps,and the corresponding position resolution is(1.8±0.2)cm,it has good time performance while having the function of beam spot reconstruction,besides,particle identification is well achieved by combining other detectors in front of the secondary target.As a new design scheme of the starttime detector,it can be used as a reference.