HBD Gas and QE Monitoring Craig Woody BNL HBD Working Group Meeting October 19, 2005

C.Woody, HBD Working Group Meeting, 10/19/052 HBD Gas System Single pass system for Run 6 Input Output Not initially instrumented

C.Woody, HBD Working Group Meeting, 10/19/053 Gas Monitoring McPherson 234/302 VUV spectrometer Uses pure argon as reference gas (no vacuum) H 2 0 O 2 VUV transmission Gas monitoring near detector (under stairs by labyrinth)

C.Woody, HBD Working Group Meeting, 10/19/054 Oxygen and Water Sensors GE Infrastructure Sensing (GE Panametrics) MIS1 system 6 dual channel inputs One moisture, one oxygen (aux input) per channel Control unit in hand, sensors ordered M2LR moisture probe O2X1 oxygen sensor Will monitor H 2 O and O 2 on common gas input and separately on east and west detector outputs

C.Woody, HBD Working Group Meeting, 10/19/055 Gas Transmission Monitoring  Based on McPherson 234/304 VUV monochrometer  Use high intensity D 2 lamp to provide sufficient current for CsI PMTs operated in photodiode mode  Constant monitor of lamp intensity  Measure common gas input and east and west gas outputs separately using motorized translatable mirror. D 2 Lamp Monochromator Focusing elements Beam Splitter Reference CsI PMT CsI PMTs MgF 2 Window Gas Cells Common input East Output West output MgF 2 Window Motor control Movable Mirror LC switch pA

C.Woody, HBD Working Group Meeting, 10/19/056 System Throughput 12 mm Beam spot at end of 50 cm gas cell (12 mm collimator)

C.Woody, HBD Working Group Meeting, 10/19/057 McPherson System in HBD Lab

C.Woody, HBD Working Group Meeting, 10/19/058 Photocathode currents D2 Lamp Upper Beam Light Coll. Box Lower Beam Slits Monochromater Cross Beam Splitter Flux and PMT current measured at three locations: Output of the light collection box Top flange of cross Lower flange of cross Peak currents are ~ nm with a 30 W D 2 lamp Currents are < 10 pA below 120 nm  Probably will want to use 150 W D 2 lamp (water cooled), but must check efficiency B.Azmoun

C.Woody, HBD Working Group Meeting, 10/19/059 Keithley Current Measuring System

C.Woody, HBD Working Group Meeting, 10/19/0510 Quantum Efficiency Monitoring Two possible methods:  DC UV lamp and measure current Measure current from mesh Cannot easily measure using HV module (100 nA resolution) Could use current switch and series picoammeter, but this complicates the HV distribution system  Pulsed UV lamp and use FEM readout

C.Woody, HBD Working Group Meeting, 10/19/0511 Grounding System HV Supply LV Supply FEM Preamp Board GEM Detector HV Distribution Box +6.5 V -7.0 V MVD Rack return

C.Woody, HBD Working Group Meeting, 10/19/0512 Xenon Flash Lamps Size ~ mm diameter Power: W Energy per pulse: Joules  ~ 2 x photons per pulse in wavelength range nm Time jitter ~ ns Frequency up to 300 Hz Properties Time jitter requires external trigger trigger from PPG (like EMCAL laser) monitor with photodiode (  timing signal) Must provide large attenuation Possible problem with RF noise Possible Problems Can test this with full scale prototype

C.Woody, HBD Working Group Meeting, 10/19/0513 Mounting Install 1” MgF 2 windows