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HBD Gas and QE Monitoring

HBD Gas and QE Monitoring. Craig Woody BNL. HBD Working Group Meeting October 19, 2005. HBD Gas System. Not initially instrumented. Input. Output. Single pass system for Run 6. Gas Monitoring. Gas monitoring near detector (under stairs by labyrinth). H 2 0 O 2 VUV transmission.

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HBD Gas and QE Monitoring

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

  2. HBD Gas System Not initially instrumented Input Output Single pass system for Run 6 C.Woody, HBD Working Group Meeting, 10/19/05

  3. Gas Monitoring Gas monitoring near detector (under stairs by labyrinth) • H20 • O2 • VUV transmission McPherson 234/302 VUV spectrometer Uses pure argon as reference gas (no vacuum) C.Woody, HBD Working Group Meeting, 10/19/05

  4. Oxygen and Water Sensors O2X1 oxygen sensor M2LR moisture probe 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 Will monitor H2O and O2 on common gas input and separately on east and west detector outputs C.Woody, HBD Working Group Meeting, 10/19/05

  5. Focusing elements Beam Splitter Movable Mirror Monochromator Motor control MgF2 Window Reference CsI PMT Gas Cells Common input East Output West output D2 Lamp pA MgF2 Window LC switch pA CsI PMTs Gas Transmission Monitoring • Based on McPherson 234/304 VUV monochrometer • Usehigh intensity D2 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. C.Woody, HBD Working Group Meeting, 10/19/05

  6. System Throughput 12 mm Beam spot at end of 50 cm gas cell (12 mm collimator) C.Woody, HBD Working Group Meeting, 10/19/05

  7. McPherson System in HBD Lab C.Woody, HBD Working Group Meeting, 10/19/05

  8. Upper Beam Light Coll. Box Monochromater Lower Beam Slits Beam Splitter Cross D2 Lamp Photocathode currents • 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 ~ 260 pA @ 160 nm with a 30 W D2 lamp Currents are < 10 pA below 120 nm B.Azmoun  Probably will want to use 150 W D2 lamp (water cooled), but must check efficiency C.Woody, HBD Working Group Meeting, 10/19/05

  9. Keithley Current Measuring System C.Woody, HBD Working Group Meeting, 10/19/05

  10. 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, 10/19/05

  11. Grounding System MVD Rack HV Distribution Box HV Supply FEM GEM Detector Preamp Board LV Supply +6.5 V -7.0 V return C.Woody, HBD Working Group Meeting, 10/19/05

  12. Xenon Flash Lamps Properties • Size ~ 20-30 mm diameter • Power: 10-20 W • Energy per pulse: 0.15-0.5 Joules •  ~ 2 x 1016 photons per pulse • in wavelength range 100-200 nm • Time jitter ~ 100-200 ns • Frequency up to 300 Hz Possible Problems • 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 Can test this with full scale prototype C.Woody, HBD Working Group Meeting, 10/19/05

  13. Mounting Install 1” MgF2 windows C.Woody, HBD Working Group Meeting, 10/19/05

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