In this paper we describe a programme of assessment carried out for the selection, based upon the performance under irradiation, of Lead Tungstate crystals for use in the Forward Tagger device, part of the CLAS12 detector in Hall B at Jefferson Lab. The crystals tested were acquired from SICCAS, the Shanghai Institute of Ceramics, Chinese Academy of Sciences. The tests performed are intended to maximise the performance of the detector within the practicalities of the crystal manufacturing process.
Results of light transmission, before and after gamma ray irradiation, are presented and used to calculate dk, the induced radiation absorption coefficient, at 420 nm, the peak of the Lead Tungstate emission spectrum. Results for the SICCAS crystals are compared with identical measurements carried out on Bogoroditsk samples, which were acquired for the Forward Tagger development program before the closure of the facility.
Also presented are a series of tests performed to determine the feasibility of recovering radiation damage to the crystals using illumination from an LED, with such illumination available in the Forward Tagger from a light monitoring system integral to the detector.
|Number of pages||8|
|Journal||Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment|
|Publication status||Published - 23 Mar 2015|