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Quartz Detectors A. Ahmidouch, NC A&T Hall C 12 GeV Workshop, August 4-5, 2008. Hodoscope S2 Placed at +265 cm from the focal plane, in front of the Lead-Glass calorimeter Quartz detector S2Y: Most dramatic change from the standard HMS hodoscope design Needed to:
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Quartz DetectorsA. Ahmidouch, NC A&THall C 12 GeV Workshop, August 4-5, 2008 Hodoscope S2 Placed at +265 cm from the focal plane, in front of the Lead-Glass calorimeter Quartz detector S2Y: Most dramatic change from the standard HMS hodoscope design Needed to: Provide a clean detection of charged particles 2. Provide a high level of background rejection 3. Provide accurate tracking efficiency determination
Beam envelope: X(-55,60cm) and Y(-50,55cm)10 quartz bars: 115 x 11 x 2.5 cm3 , with 0.5 cm overlap
Completed R&D work so far: • Completed R&D task: Prototype of Quartz Detector • By Dave Mack report 12/16/2007 • Summer 2006: Patrick McCarter NCA&T Undergraduate student worked on: • Use Monte Carlo ntuples to define the size of the detectors • Ordered PMTs for cosmic tests • Selecting the appropriate UV transparent glue
Choice: Artificial fused silica, has good properties: • UV transparent • radiation hard* • low luminescence • BABAR DIRC tests Spectrosil 2000 (St Gobain) and JGS1-UV (Scionix) best choice. Q-Weak uses spectrosil 2000 • Optical uniformity: optical grade polish 25 A rms, flatness 200 mm • Checking with: (many companies…) • Cosmo Optics • Case Corp. • New Rise Optics • Advanced Glass Industries • Use UV sensitive 3-in PMTs, Hamamatsu H6526
*Radiation hardness n-l dependence
Pulse height spectrum • Index of refraction n =1.47 • Threshold velocity bth = 0.68 • Qweak: 150 pe, for 2.5 cm thickness > 60 pe required
To Do List: • Build and test the prototype bar. • Build the 10 + 1(spare) quartz bars with PMTs. • Test quartz detectors. • Deliver the detectors to Hall C and mount them on frame. • Assemble the quartz detector. Not included: • Cables + Electronics • High voltage power supply
Status of funding • NSF-MRI grant: $228,847 • Quartz bars • PMTs + dividers + magnetic shielding • Some travel • Regular NSF grant: • Travel • Student labor
Schedule of Tasks • 2008 Procurement and test of the prototype bar with cosmics • 2008-2009 Procurement of quartz bars and PMTs build the 10+1 bars test with cosmics • 2009-2010 Deliver quartz bars to Jlab and assemble on frame • 2011-2014 Installation in SHMS and commissioning Manpower • Two faculty: AA & SD • One graduate and one undergraduate student (probably more)