1. HBD Status for Run 10 C.Woody For the HBD Group Collaboration Meeting January 15, 2010

2. C.Woody, HBD Status, PHENIX Collaboration Meeting, 1/15/102 HBD East was Removed and Completely Refurbished during the 2009 Shutdown HBD East reinstalled on 10/1/09 HBD East was removed for refurbishing on 8/26/09 Refurbishing was completed in record time (35 days!) All problematic GEMs were either repaired (washed) or replaced All new CsI GEMs were installed using the Rapid Method, which gives minimal exposure inside the glove box

3. C.Woody, HBD Status, PHENIX Collaboration Meeting, 1/15/103 Rapid Method Standard GEMs installed near laminar flow table (cleanest area inside tent) CsI coated GEMs installed inside glove box (minimize exposure time) Same method was used for HBD West which performed much better than the East in Run 9

4. C.Woody, HBD Status, PHENIX Collaboration Meeting, 1/15/104 Problem with EN2 GEMs held voltage well beyond operating, but first transfer gap would not Due to time constraints, we adopted a workaround solution: Go back to old voltage divider with lower voltage in 1 st transfer gap and compensate with higher gain in GEMs Initial testing and diagnosis resulted in some damage to top and middle GEMs (2 partial shorts), but seemed ok After going to full operation at the start of Run 10, EN2 developed several additional shorts Attempted to compensate for this during the last access (1/7). Still has some HV problems, but seems like we can get to an operating voltage that will give an acceptable gain

5. C.Woody, HBD Status, PHENIX Collaboration Meeting, 1/15/105 CsI Quantum Efficiency QE of new photocathodes Scintillation Cube Photocathodes produced over one year ago have not deteriorated in terms of their QE Monitor QE using CF 4 scintillation as a calibrated light source HBD West HBD East B.Azmoun

6. C.Woody, HBD Status, PHENIX Collaboration Meeting, 1/15/106 Gas Transmission Monitor Transmission monitor suffered some aging effects over the last 2 years resulting from operating the system under vacuum All optics were replaced during the 2009 shutdown. Sensitivity is now better than when originally delivered ! Will operate under argon flow from now on B.Azmoun

7. C.Woody, HBD Status, PHENIX Collaboration Meeting, 1/15/107 Gas Transmittance Output ~ 20 ppm H 2 O and ~ 1 ppm O 2 Input ~ 0 ppm H 2 O and O 2 Flow rate ~ 4.75 lpm to each detector B.Azmoun, S.Stoll1/8/10

8. C.Woody, HBD Status, PHENIX Collaboration Meeting, 1/15/108 New Reduced Data Format Old 12 sample format Data volume ~ 20-24 KB/ev New 3 sample format Data volume ~ 7-8 KB/ev S.Bathe Rate: KHz Run Number

9. C.Woody, HBD Status, PHENIX Collaboration Meeting, 1/15/109 Pedestals and Noise ~ 1.5 chs ~ 900 e’s ~ 0.3 pe New format T.Sakaguchi

10. C.Woody, HBD Status, PHENIX Collaboration Meeting, 1/15/1010 Setting Gains Using Scintillation Select on most peripheral events where << 1 Ionization Scintillation 1 p.e. Forward Reverse S.Rolnick

11. C.Woody, HBD Status, PHENIX Collaboration Meeting, 1/15/1011 West Gains BBC Cut 20 S.Rolnick

12. C.Woody, HBD Status, PHENIX Collaboration Meeting, 1/15/1012 East Gains BBC Cut 20 S.Rolnick

13. C.Woody, HBD Status, PHENIX Collaboration Meeting, 1/15/1013 Setting Reverse Bias Voltages (dV Scan) Operating Point Need to set reverse bias voltage to optimize pe collection efficiency and minimize hadron response Requires setting voltage between mesh and top GEM to ~ 5V Applied voltage is ~ 4KV, so this requires high precision (~ 0.1%) and good stability in the HV PS Charged particles Photo electrons -5V -10V -5V -10V -15V ES1 ES2 ES3 ES4 ES5 EN1 EN2 EN3 EN4 EN5 S.Rolnick

14. C.Woody, HBD Status, PHENIX Collaboration Meeting, 1/15/1014 HBD HV Control M.Proissl

15. C.Woody, HBD Status, PHENIX Collaboration Meeting, 1/15/1015 Scintillation in Au-Au Estimate of Npe per pad due to scintillation in Au-Au using Run 7 data Occupancy is high in MB  central collisions ! I.Ravinovich

16. C.Woody, HBD Status, PHENIX Collaboration Meeting, 1/15/1016 per pad with high centrality cut (Run 10) WS3 = 6.9 WS4 = 7.3 WN3 = 7.7 WS4 = 7.9 Effect of Scintillation on Single vs Double Electron Separation =10 Double Single  single ~ 80%  double ~ 76% Monte Carlo Single vs Double Electrons with Scintillation Z.Citron Measured Single and Double Electron Spectra (Run 9) I.Ravinovich ~ 25% decrease due to scintillation in central collisions 3 pad clusters Npe single = 22 pe S.Rolnick

17. C.Woody, HBD Status, PHENIX Collaboration Meeting, 1/15/1017 Electron Backgrounds from Run 9 P.Garg MBERT

18. C.Woody, HBD Status, PHENIX Collaboration Meeting, 1/15/1018 Overall Summary  Both East and West detectors are installed and operational. Gains and dV’s are roughly set  One problematic module seems to be working  Quantum efficiencies are good  Gas quality is good  New FEM code installed and working and data volume is acceptable  Scintillation in Au+Au is high, but looks like it is manageable