Collaborative Research: Development of a Particle Tracking System for the Qweak Experiment

George Washington University, Washington DC

Investigators

Abstract

Ohio University will design and build two sets of trigger scintillators for the Qweak experiment at Jefferson Lab. This important new experiment will measure the weak charge of the proton, as a precision test of the running of the weak mixing angle, thus providing a uniquely sensitive probe of physics beyond the Standard Model of particle physics. The trigger scintillators are an essential component of the Qweak particle tracking system, and will be used to start the electronics and to veto neutral particles during the calibration and background measurements. Each scintillator will be 225 cm x 16 cm x 1 cm and made from BC408 or its equivalent. Non-UVT lightguides at each end will provide a mechanically reliable optical coupling joint. UVT rods that are 5.1 cm in diameter and 5 cm long will couple the rectangular lightguide to the photomultiplier tubes. The long edges of the scintillators will be diamond milled and the ends finished to a 600 grit sanded finish. Given the extreme ratio of thickness to length, the scintillator counters must be supported by a frame which is then mountable to the rear chamber package. To reduce radiation damage, this package will be removed from direct view of the beam for the high current running mode. The assembly and testing of the detectors will be done at the Ohio University Institute for Nuclear and Particle Physics by a graduate student and at least one undergraduate student, under the supervision of Professor Opper. The Ohio University group will also develop the fast triggering system which is required for this experiment. When the detectors have been deemed ready for installation, the students will participate in their commissioning at Jefferson Lab.