Development of a New-typed Start-time Detector Based on SiPM

In this paper, a new type of start-time detector is developed. The sensitive area of the detector is 60 mm×60 mm, which is divided into two layers of dislocation tightly arranged by 120 plastic scintillating fibers with a diameter of 1mm, and three adjacent fibers are used as one detecting unit that uses the silicon phtotmultiplier to read signals. The work uses ⁹⁰Sr radiation source to test the performance of a single scintillating fiber, the results show that the propagation speed of light in the fiber is about 17 cm/ns, and the corresponding time resolution is better than 600 ps. Besides the test using ⁹⁰Sr source, the detector's performance has also been inspected through the ¹⁵N secondary beam of 240 MeV/u provided by the second radioactive beam line at Lanzhou (RIBLL2) of Institute of Modern Physics, Chinese Academy of Sciences. The in-beam test results show that the time resolution and vertical position resolution of the detector are (150±15) ps and (1.8±0.2) cm respectively. Combined with the detector and other detectors on the RIBLL2 External Target Facility, various isotope particles of 5 ≤ Z ≤ 8 generated in the experiment can be well identified.