Slide 1

Collimation and tagging instrumentation for the GlueX photon beamline Richard Jones Igor Senderovich, Anne-Marie Carroll University of Connecticut APS/DNP meeting, Newport Beach, Oct 24-27, 2012 Slide 2 APS/DNP meeting, Newport Beach, Oct. 24-27, 20122 Top View 75 m Tagger Area Experimental Hall D Electron beam / dump Coherent Bremsstrahlung photon beam Solenoid- Based detector Collimator Photon Beam dump Counting House Radiator PairSpectrometer Collimator Cave Beam contains both coherent and incoherent components. Only the coherent component is polarized. Only the coherent component is polarized. Collimation suppresses incoherent part. Eg (GeV) intensity (/GeV) no collimator with collimator Tagging Spectrometer Beamline Overview Slide 3 APS/DNP meeting, Newport Beach, Oct. 24-27, 20123 Tagging spectrometer crystal radiator 12 GeV electrons post-bremsstrahlung electrons focal plane hododscope 500 scint. fibers 2mm x 2mm SiPM readout 3MHz rate/fiber s t = 200ps Slide 4 APS/DNP meeting, Newport Beach, Oct. 24-27, 20124 Photon collimator crystal radiator 12 GeV electrons photon beam collimator (75m downstream) 3.4mm aperture ~5mm RMSphoton spot ~5mm RMS 15% power transmission shielded alcove Slide 5 APS/DNP meeting, Newport Beach, Oct. 24-27, 20125 Collimator requirements x < 200 m dynamic range resolution bandwidth robustness 0.5 nA 5 A 200 m RMS > 60 Hz radiation hardradiation hard stable gainstable gain reliablereliable Slide 6 APS/DNP meeting, Newport Beach, Oct. 24-27, 20126 Collimator design Tungsten pin-cushion design Miller and Walz, NIM 117 (1974) 33-37 measures current due to knock- ons in EM showers 12 cm beam tungsten plates tungsten pins insulating support tungsten pin cushion incident gamma e+ e- charge asymmetry comes from high-energy delta rays knock-ons Slide 7 APS/DNP meeting, Newport Beach, Oct. 24-27, 20127 Beam test April 2011 James McIntyre Brendan Pratt Igor Senderovich +Alex Somov, Hovanes Egyan prototype detector installed in Hall B photon dump area Slide 8 APS/DNP meeting, Newport Beach, Oct. 24-27, 20128 Run conditions beam energy: 3.36 GeV current: 15 nA, 60 nA precollimator: 2.6 mm radiator: 10 -4 radiation lengths, gold stability very good sampling frequency 333kHz Slide 9 APS/DNP meeting, Newport Beach, Oct. 24-27, 20129 Active collimator data sweep collimator horizontally across beam, observe raw currents on wedges Slide 10 APS/DNP meeting, Newport Beach, Oct. 24-27, 201210 Active collimator data near the aperture look at asymmetry raw offsets not removed gain ~ 15% / mm centered at 14.28 cm V right V left V left + V right Slide 11 APS/DNP meeting, Newport Beach, Oct. 24-27, 201211 Active collimator data electronic noise is negligible raw asymmetry signal: moving through beammoving through beam out of beamout of beam Slide 12 APS/DNP meeting, Newport Beach, Oct. 24-27, 201212 Active collimator data results @ 60nA beam noise floor: readout noise floor amplifier bandwidth 18 m @ 600Hz scaling to 0.6nA 130 m @ 120Hz beam noise floor digitization noise floor 3 m @ 600Hz readout noise floor