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HBD R&D update:

HBD R&D update:. Itzhak Tserruya Upgrades meeting March 10, 2004. Outline. • Simulations • “Practical” R&D - CsI absolute quantum efficiency - Time dependence - GEM operation w/o pumping - HV segmented GEMs - Asymmetric operation • Prototype

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HBD R&D update:

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  1. HBD R&D update: Itzhak Tserruya Upgrades meeting March 10, 2004

  2. Outline • Simulations • “Practical” R&D - CsI absolute quantum efficiency - Time dependence - GEM operation w/o pumping - HV segmented GEMs - Asymmetric operation • Prototype • Outlook

  3. Slow Simulation (detector response) Reconstruction (Fun4All) PISA Simulations The whole machinery exists: - Geometry of HBD-only in PISA  committed to CVS - slow simulation basically using Sasha’s program - event reconstruction in Fun4All framework Fairly well debugged  Ready to be used

  4. Geometry Geometry seems to be in reasonably good shape

  5. p = 20 MeV/c p = 30 MeV/c p = 40 MeV/c p = 50 MeV/c p = 100 MeV/c p = 200 MeV/c p = 300 MeV/c p = 500 MeV/c p = 1000 MeV/c Single electron response: blob shape • Relatively small deformation of the circular shape for low momentum electrons p ≤ 40 MeV/c

  6. Single electron response: npe Cell threshold: 8fC (5pe) , Cluster threshold: 25fC (16fC) • <npe> = 50 • (includes 1cm frame width  10% dead area ) • <npe> = 38 • after correcting for: • - optical transparency mesh (90%) • - optical transparency of GEM (81%) • - smaller dead areas of 5% :

  7. Central HIJING Cell threshold: 8fC (5pe) , Cluster threshold: 25fC (16fC) Central arm combinatorial spectrum w/o HBD rejection HBD response Events look clean enough. HBD could be used to generate clean electron trigger.

  8. Slow Simulation (detector response) Reconstruction (Fun4All) PISA Simulations The whole machinery exists: - Geometry of HBD-only in PISA  committed to CVS - slow simulation basically using Sasha’s program - event reconstruction in Fun4All framework Fairly well debugged  Ready to be used • Three main tasks: • HBD response to single electrons • 2-hit separation & optimization of pad size • Rejection of combinatorial background

  9. CsI Photocathode QE The most attractive option: • Transmissive photocathode • Relatively high QE CF4 & CsI: Very large bandwidth: 6 – 11.5 eV Very large N0 940: 40 pe in a 50cm long radiator (including transparency of mesh and first GEM) electron efficiency > 90%

  10. CsI absolute QE: set-up Rotatable UV mirror Bandwidth: 6.2 – 10.3 eV PMT-2 and CsI have same solid angle C1 optical transparency of mesh (81%) C2 opacity of GEM foil (83.3%) All currents are normalized to I(PMT-1) QE(CsI) = QE(PMT-2) x I(CsI) / I(PMT-2) x C1 x C2

  11. CsI QE: results N0 measured in range 6.2-10 eV = 414 cm-1 in CF4 N0 extrapolated to 11.5 eV (ignoring last measured point) = 915 cm-1 in v.g. agreement with the value of 940 cm-1 used in the proposal (Extrapolation to 0 QE using last point gives N0 = 600 cm-1 )

  12. 2.24.04 -100 V for 30’ 3.1.04 Open detector to air Close with double mylar window and operate w/o pumping 2.21.04 -100 V for 15’ Time dependenceHistory of the CsI + triple GEM that we have been using from Aug. 4, 2003 till March 8, 2004. HV off. Flow Ar/CO2 1.8 to 24.1.2004 spark HV lowered from 480V to 460V on Sept. 9, 2003 Pump, restore CF4 flow and HV on 1.24.04

  13. Other R&D issues expected to be completed during March-May 04 • Test of HV segmented tests (sparking probabilities) already started • GEM operation in realistic conditions, no pumping (no stainless-steel vessel?) already started • Asymmetric operation scheduled in April • GEM test in Au-Au environment (Craig, Bob …) on-going • Test at KEK to measure N0, hadron blindness (SUNY, Tokyo, Weizmann) scheduled in the week of May 18

  14. Prototyping Three steps are planned: • Three panel production * all mechanical parts and jigs have been produced * scheduled end of March • Full size HBD box * all raw materials have been ordered * scheduled in June • GEM frames  minimize frame width * scheduled in April

  15. Conclusions and Outlook • Progress in the hardware and R&D issues • Start on the simulations: • We should be ready to start the final design of the HBD in the summer. • Construction could start soon after that.

  16. Conclusions and Outlook

  17. Conclusion and Outlook • I think that the proof of principle exists. • We still have a number of issues to study: - asymmetric operation of GEMs - HV segmentation - operate without pumping - beam tests …. • But we are ready to start the practical R&D: - design of a real detector. - develop construction and assembly procedures

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