Simulations and Test Results of Large Area Continuous. Position Sensitive Diamond Detectors

摘要

Continuous Position Sensitive Diamond Detector (CPSDD) development started by using the single crystal (sc) diamond material. The intrinsic high detection efficiency of sc diamond, providing a high Signal to Noise (S/N) ratio, allowed the full testing of CPSDD with alpha-particles. However, due to the size limitations of sc diamond, the development of Large Area CPSDD (LACPSDD) naturally evolved towards the use of polycrystalline (pc) diamond material, produced by chemical vapor deposition (CVD). The charge generated by the particle or radiation impact is collected through diamond like carbon (DLC) layers and associated metallic electrodes deposited on the sides of the pc diamond plate. The incident particle position can be obtained via charge division measurement by using charge sensitive amplifiers (CSA) connected to each electrode. In this paper we report the improvement in LACPSDD design by showing results obtained for two pc diamond detector (pcDD) structures. The first pcDD has a DLC layer with four electrodes at the corners of the front side, whereas the back side is fully metallized. The second pcDD has DLC layers on both sides of the detector plate, each equipped with two parallel electrode strips, along the x and y axis, respectively. Experimental results on the first pcDD showed an ion rate limitation, caused by the increase in the detector time constant (because of the larger detection area), and a low S/N ratio, due to the specific reduced signal associated with low Charge Collection Efficiency (CCE) of pc diamond. Subsequently, by using an optimized electronics and a better pc diamond (higher CCE), the second pcDD shows a higher S/N ratio, as well as a lower time constant. This paper presents simulation results on the time constant and an analytical evaluation of the S/N ratio, which serve to optimize the pc LACPSDDs. We also show experimental test results with alpha-particles, as well as Ni-54 (1.7 AGeV) and C-12 (11.4 AMeV) ion beams.