Quartz DetectorsA. 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 thestandard HMS hodoscope design

Needed to:

1. Provide a clean detection of charged particles

2. Provide a high level of background rejection

3. Provide accurate tracking efficiency determination

SHMS detector package side view

Quartz detector S2Y

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:

• 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

Completed R&D task: Prototype of Quartz DetectorBy Dave Mack report 12/16/2007

• 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 m

• 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- dependence

Pulse height spectrum

• Index of refraction n =1.47

• Threshold velocity

th = 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)