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Malek MAZOUZ

Malek MAZOUZ. The 18 th of May 2004. Hall A collaboration meeting. LPSC Grenoble. n-DVCS /E03-106 status report. - Tagger description Electronics Experimental tests Mechanics Simulations. M. Mazouz. Detection in proton array (~20% of efficiency). Detection in Left HRS.

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Malek MAZOUZ

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  1. Malek MAZOUZ The 18th of May 2004 Hall A collaboration meeting LPSC Grenoble n-DVCS/E03-106status report • -Tagger description • Electronics • Experimental tests • Mechanics • Simulations

  2. M. Mazouz Detection in proton array (~20% of efficiency) Detection in Left HRS Detection in PbF2 electromagnetic calorimeter • Mostly sensitive to GPD E(unknown !) • Information about quark orbital angular momentum through models and Ji’s sum rule • Use of a deuterium target • Proton DVCS ( e d e γ p (n) ) is veto-ed by new detector

  3. Tagger M. Mazouz • Two scintillator layers: • 1st layer: 28 scintillators, 9 different shapes • 2nd layer: 29 scintillators, 10 different shapes Proton array

  4. M. Mazouz The 57 scintillators of the tagger

  5. M. Mazouz The light guide is glued to the scintillator using a UV glue

  6. M. Mazouz Scintillator and its guide are wrapped with aluminium and black tedlar

  7. M. Mazouz All tagger scintillators and light guides are glued and wrapped (thanks to Kathy’s hard work!)

  8. To reduce the dynode current: Reduction of the PMT Gain Use of an amplificator(gain~10) LPSC Grenoble designed and tested the PMT bases. M. Mazouz Electronics : LPC Clermont-Ferrand supplied and tested 70 PMTs and determined their characteristics • Hamamatsu R7788 PMT • # of dynodes : 8 • Gain at 650 Volts : 1. 105 • Rise time : 1 ns • Decay time : 2 ns

  9. HV-Signal-DC out Connectors Amplification board HV distribution board LV (+/-5V) daisy chain connectors PMT M. Mazouz 5 cm PMT + base

  10. PMT box At present we are testing the set {PMT+base+light guide+scintillator} M. Mazouz Assembled paddle

  11. M. Mazouz Experimental Tests Scintillator S1 Wire chamber H Wire chamber M Prototype Wire chamber B Scintillator S2

  12. events Amplitude (mV) Amplitude histogram for a paddle (1st layer) Wire chambers Coordinates of each event Paddle light collection map : Relative average Amplitude in this cm² : Number of events in this cm² for each cm² : : Total number of events per paddle M. Mazouz Light collection uniformity

  13. M. Mazouz Light collection uniformity Light collection map for the five different shapes of the first layer. The variation of the light amplitude is about 30% at most. Paddles of the 2nd layer are being tested this week.

  14. M. Mazouz Mechanics: The main shielding : built by the workshop of LPSC Grenoble The middle shielding (between the two scintillator layers) and the light tight cover will be finishednext week.

  15. Studies to be performed: • Background rates in the two scintillator layers • Neutron detection efficiency of the proton array • n-DVCS events distribution in the detector • … M. Mazouz Simulations: The final geometry of the tagger has been introduced in the simulation program GEANT

  16. M. Mazouz Planning : -Delivery time of cables and connectors : next week -Detector Assembly at LPSC Grenoble : 3rd week of June -Shipment to JLAB : End of June -Detector assembly and tests at JLAB: July -Hall A installation: August -Beginning of DVCS experiment: 20th of September -n-DVCS experiment: from October 31sttill November 24th

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