A Scintillating Fiber Hodoscope for a Bremstrahlung Luminosity Monitor at an Electron − Positron Collider
D.H. Brown, D.H. Orlov, G.S. Varner, W.A. Worstell, S.I. Redin
Abstract
The performance of a scintillating fiber (2mm diameter) position sensitive detector (
4.8×4.8
cm
2
active area) for the single bremstrahlung luminosity monitor at the VEPP-2M electron-positron collider in Novosibirsk, Russia is described. Custom electronics is triggered by coincident hits in the X and Y planes of 24 fibers each, and reduces 64 PMT signals to a 10 bit (X,Y) address. Hits are accumulated (10 kHz) in memory and display (few Hz) the VEPP-2M collision vertex. Fitting the strongly peaked distribution (
∼
3-4 mm at 1.6m from the collision vertex of VEPP-2M ) to the expected QED angular distribution yields a background in agreement with an independent determination of the VEPP-2M luminosity.