Development of electron detectors for the BRAND experiment

The advanced version of BRAND-II experiment will utilize a long plastic scintillator bar (100 × 10 × 1) cm3 for the measurement of energy deposited by the electrons originating from neutron decay (direct and Mott-scattered electrons). The commercially available EJ200 scintillator is particularly suitable for this application due to its significant light attenuation length of 380 cm.Two Hamamatsu PMTs (R1828-01) are coupled to the scintillator at both ends via light guide. To enhance light collection, the light guide adapter and three faces of the scintillator are wrapped with a 98% reflective film (3M ESR), while the front face is wrapped with aluminized Mylar. The scintillator was scanned with a 241Am source (59 keV gamma, dia 2 mm) and 207Bi source (two conversion electron line groups around 480 and 1000 keV, dia 0.5 mm). These sources were directly placed on the scintillator front face.Figures show the measured response using 241Am (59 keV gamma) and 207Bi (1 MeV conversion electron), demonstrating an almost uniform distribution with a maximum deviation of approximately 2% along the scintillator.The percentage deviation in the geometrical mean (GM) with respect to the average value is shown as well.