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Hadron Blind Detector Update

Hadron Blind Detector Update. I. Ravinovich WIS. HBD milestones for Run-9. Reach a stable operation of the GEM modules Improve the transmission of the radiator Check the tracking and alignment Space gain equilibration in each module Reverse bias HV settings for each module

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Hadron Blind Detector Update

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  1. Hadron Blind Detector Update I. Ravinovich WIS I. Ravinovich

  2. HBD milestones for Run-9 • Reach a stable operation of the GEM modules • Improve the transmission of the radiator • Check the tracking and alignment • Space gain equilibration in each module • Reverse bias HV settings for each module • Determine hadron MIP response in RB mode • Determine “single” electron response • Determine “double” electron response • Determine hadron Cherenkov response in (++) I. Ravinovich

  3. HBD operation during 500 GeV run • There are NO trips which are related to the GEMs themselves. • There are NO trips due to the sudden gain increase related to the weather changes (P/T). We have 5 sets of HV settings for different P/T values, so HV software takes care of it between the runs if there a need for it. • From time to time there are simultaneous trips in 4 modules WS1, WS2, WS3, and WN5 which are powered by the same 1471N LeCroy PS and the same relay board. This problem will be investigated during the access today and hopefully solved. • Up to now we have 8 dead HV segments on 6 GEMs, 1 was there already at SB, 6 developed in the beginning of run, 1 in the end of March. The resistors have been changed, so the modules are fully operational. Let’s call it “start-up effect”. • Let me remind you that 1 HV segment is 3.6% of the module area, so 8 dead strips correspond to 1.4% of the PHENIX Central Arms acceptance. • One module ES1 is not operational due to the short between the mesh and top GEM. There is nothing that can be done. This module is on the edge of the acceptance, it corresponds to 2.5% dead area of it. I. Ravinovich

  4. The radiator transmission HBD-Ar @ 2.25lpm (straight-through mode, no scrubbing) (2.5hrs. of flow thru cells) HBD-CF4 @ 4.5lpm (Recirculation mode, incl. scrubbing)

  5. Tracking and alignment • Used zero field runs. • HBD was operated in forward bias mode in order to see the hadrons MIP. • The reconstructed hadron tracks in Central Arms are projected to HBD. • Each module was aligned according to the matching in both directions. I. Ravinovich

  6. Space gain equilibration • The module gain non-uniformity over the GEM area originates from the variations of the hole diameter coming from GEM production process, and the gain is a very strong function of the hole diameter. There is nothing that we can do rather than correct it offline for each particular module. I. Ravinovich

  7. HV scans have been performed for each individual module tuning the drift field between the mesh and the top GEM in each case ES1 =-10V Red (+5V), black (0V)‏ green(-5V),blue(-10V), rest(-15V and lower)‏ I. Ravinovich

  8. Hadrons MIP response • Runs in (+-) field. • HBD in reverse bias. • The reconstructed hadron tracks in Central Arms are projected to HBD. • The residual dE/dx charge is very small wrt electron response that will be shown on the next slide, so there is no problem with hadron rejection. I. Ravinovich

  9. Single vs double electron response: used the electrons from Dalitz pairs in the mass region below 150 MeV. The separation between isolated electrons and unresolved doubles is there. The number of p.e. is ~22, more than 50% increase wrt Run-7 value. I. Ravinovich

  10. Cherenkov response of high momentum hadrons • Runs in (++) field. • Reconstructed high momentum hadrons (> 5 GeV/c) are projected to HBD. • Their Cherenkov response is in place. I. Ravinovich

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