用于放射性束物理的新型大面积反符合探测技术研究

In order to study the nuclei far from the valley of β stability line even near the drip-line, several charged particle detectors and neutron detectors have been developed at ETF of CSR-RIBLLII. The anti-coincidence veto detector, one of the key detectors at ETF is designed to reject charged particles. As the interesting exotic nuclei are approached to drip-line gradually, the intensity of radioactive ion beams becomes very extremely sparse, and this would be possible to obtain a wrong experiment result if the anti-coincidence veto detector could not suppress or reject the total number of the mixed charged particles effectively. The original anti-coincidence veto detector readout by double PMTs is no longer meet requirements in nuclear physics experiments for their poor veto efficiency to charged particles. . A new-type anti-coincidence veto detector will be developed to increase the veto efficiency and uniformity by using scintillator counter with Wave shift length fibre (WLS) and readout by a new-type photoelectric device named silicon photomultiplier (Si-PMT). Detailed studies will be applied to single Si-PMT and its array, WLS, configuration and dimension of detector, process of detector, absolute light production of detector, etc.al, also to the readout electronics to obtain high veto detection efficiency of charged particles. To Minimum Ionizing Particles (MIPs), this new-type detector will reach a high detection efficiency of 99% at different hit position, and a cosmic ray test and a beam test will be implemented to verify the performance of the new detector to improve the reliability of the exotic nuclear physics experiment.

为了研究远离β稳定线乃至滴线附近的原子核结构与性质，CSR-RIBLLII外靶实验终端发展了一系列探测器，其中Veto探测器用于消除带电粒子的干扰。随着目标奇异核往滴线附件靠近，由于束流强度极低，如果Veto探测器不能有效抑制或消除混入带电粒子总事例数，致使得到的实验结果可能错误。原有基于光倍管读出的Veto探测器由于对带电粒子的探测效率太低等原因已不能满足需求。本项目拟在塑闪材料中埋入波长位移光纤(WLS)，采用一种新型读出器件硅光倍管（Si-PMT），发展一种新的反符合探测技术。通过对Si-PMT及其阵列、WLS、探测器构型尺寸及工艺、探测器绝对光产额和读出电子学等进行细致研究，预计新型探测器样机能大幅提高反符合效率和不同位置的均匀性，对不同击中位置MIPs的探测效率均能好于99%，从而大幅提高奇异核物理实验结果的可靠性。最后，通过宇宙线和束流实验对该样机进行测试验证其实际使用性能。

为了研究远离β稳定线乃至滴线附近的原子核结构与性质，CSR-RIBLLII外靶实验终端发展了一系列探测器，其中Veto探测器用于消除带电粒子的干扰。随着目标奇异核往滴线附件靠近，由于束流强度极低，如果Veto探测器不能有效抑制或消除混入带电粒子总事例数，致使得到的实验结果可能错误。原有基于光倍管读出的Veto探测器由于对带电粒子的探测效率太低等原因已不能满足需求。本项目依托于外靶实验终端，发展了一种新的反符合探测技术，即在塑闪材料中埋入波长位移光纤(WLS)，并采用一种新型读出器件硅光倍管（Si-PMT）读出。项目对Si-PMT和WLS及探测器工艺等进行了细致研究，建立了专用的宇宙射线测试装置平台，得到了新型反符合探测单元能够大幅提高反符合效率和不同位置的均匀性的结论，其对不同击中位置MIPs的探测效率能达到99.9%，好于99%的任务书指标。利用该技术发展的新Veto探测器将大幅提高奇异核物理实验结果的可靠性。