HBD R&D at the WIS Boris Khachaturov, Alexander Kozlov, Ilia Ravinovich and Itzhak Tserruya Weizmann Institute, Israel Mini Workshop on PHENIX upgrade plans, BNL Aug. 5 -6, 2002 6 -Aug-02 Itzhak Tserruya PHENIX Upgrade mini-Workshop 1
Outline The HBD concept Goals of the R&D programme at the WI Set-up and Status Plans 6 -Aug-02 Itzhak Tserruya PHENIX Upgrade mini-Workshop 2
HBD in PHENIX • Compensate magnetic field with inner coil (B=0 for r 50 -60 cm) • Compact HBD in the inner region Specifications * Electron efficiency 90% * Modest rejection ~ 200 * Double hit recognition 90% 6 -Aug-02 HBD Itzhak Tserruya PHENIX Upgrade mini-Workshop 3
Detector Configuration Concept: • Windowless Cherenkov detector • Radiator and detector gas: CF 4 Large bandwidth and large Npe • Transmissive Cs. I photocathode No photon feedback 6 -Aug-02 Itzhak Tserruya PHENIX Upgrade mini-Workshop 4
Cs. I photocathode QE The most attractive option: Transmissive photocathode Relatively high quantum efficiency Very large bandwidth: 6 – 11. 5 e. V Very large N 0 940: 40 pe in a 50 cm radiator 6 -Aug-02 Itzhak Tserruya PHENIX Upgrade mini-Workshop 5
Detector Configuration Novel Concept: • Windowless Cherenkov detector • Radiator and detector gas: CF 4 Large bandwidth and large Npe • Transmissive Cs. I photocathode No photon feedback • No ring image as in RICH or in proximity focus blob image Low granularity • Detector element: multi - GEM High gain 6 -Aug-02 Itzhak Tserruya PHENIX Upgrade mini-Workshop 6
Detector configuration: granularity Pads 6 -Aug-02 Shape: hexagonal Dimension: app. size of the blob (R=1. 8 cm) 2000 pads to cover central arm acceptance Threshold: defined by background Itzhak Tserruya PHENIX Upgrade mini-Workshop 7
Main Goals of the R&D Programme • Demonstrate concept validity * Response to electrons and hadrons (Npe per electron and per mip) * CF 4 scintillation * Demonstrate e-efficiency and double hit recognition. 6 -Aug-02 Itzhak Tserruya PHENIX Upgrade mini-Workshop 8
CF 4 radiator gas / Alternative C 4 F 10 ? CF 4 scintillation parameters: Peak at 163 nm 100 -200 photons/Me. V and d. E/dx = 7 ke. V/cm 20 -30% Cs. I Q. E. . Results: 0. 007 ph/(MIP cm 2) 250 MIPs in one PHENIX arm 10 cm 2 size of the blob Signal / noise > 10! Shades reduce noise by a factor of 3 Timing ? 6 -Aug-02 Itzhak Tserruya PHENIX Upgrade mini-Workshop CF 4 scintillation is not a killing factor 9
Main Goals of the R&D Programme • Demonstrate concept validity * Response to electrons and hadrons (Npe per electron and per mip) * CF 4 scintillation * Demonstrate e-efficiency and double hit recognition. • Generic Detector R&D * Cs. I / CF 4 bandwidth * Gain in GEM * Aging of Cs. I and GEM in CF 4 * Optimize Detector configuration: 3 GEM or 2 GEM + MWPC? * d. E/dx in CF 4 • Monte Carlo simulations 6 -Aug-02 Itzhak Tserruya PHENIX Upgrade mini-Workshop 10
Cosmic ray signals in Ar/CO 2 70 -30 VGEM = 450 V E d = 2. 0 k. V cm – 1 E E i = 4. 5 k. V cm – 1 t = 4. 0 k. V cm – 1 S. Bachman et al. NIM 438 A (1999) 376 Gain: 4 x 104 Mounting & working with GEM 6 -Aug-02 Itzhak Tserruya PHENIX Upgrade mini-Workshop 11
CF 4 + GEM + Cs. I work! 6 -Aug-02 Itzhak Tserruya PHENIX Upgrade mini-Workshop 12
Setup: from the original sketch (end 2001)… Set up: Cherenkov counter for high momentum muons (~min-1) § Detector: double GEM (10 x 10 cm 2) + PCB § Cosmic trigger: 3 layer plastic scintillators + Cherenkov counter (in near future) Electric scheme § Two HV power supplies for more flexibility § Cathode readout 6 -Aug-02 Itzhak Tserruya PHENIX Upgrade mini-Workshop 13
Setup: …to a more elaborated sketch (1. 2002) … • Design almost complete • Manufacturing and order underway 6 -Aug-02 Itzhak Tserruya PHENIX Upgrade mini-Workshop 14
Setup: … to the full design (2. 2002) … Cherenkov cosmic ray trigger Cherenkov light reflected by 16 mirrors, in a pyramid arrangement, onto 4 large PM Mini HBD: CF 4 radiator tank + Multi –Gem detector box Scintillators 6 -Aug-02 Itzhak Tserruya PHENIX Upgrade mini-Workshop 15
Setup: … to real life (7. 28. 02) Cherenkov cosmic ray trigger Cherenkov light reflected by 16 mirrors in a pyramid arrangement onto 4 large PM Mini HBD: CF 4 radiator tank + Multi –Gem detector box Scintillators 6 -Aug-02 Itzhak Tserruya PHENIX Upgrade mini-Workshop 16
The mirror support 6 -Aug-02 Itzhak Tserruya PHENIX Upgrade mini-Workshop 17
The mirrors mounted 6 -Aug-02 Itzhak Tserruya PHENIX Upgrade mini-Workshop 18
Status & plans: Basic equipment to work with GEM is ready: UV source, x-ray and alpha sources Electronics, gas system, monochromator Double GEM detector is working at the WIS in Ar/CO 2 Gain 4. 5· 104 achieved and is consistent with measured at CERN Cs. I photocathodes routinely produced with reproducible results Moving to CF 4 within the next weeks. Cosmic ray trigger Procurement of parts and components completed (only CF 4 radiator tank is missing) Setting-up underway Mini HBD Procurement of parts and components almost completed (only CF 4 radiator tank is missing) Multi-GEM box ready. Simulations Optimize shade configuration to absorb scintillation Granularity 6 -Aug-02 Itzhak Tserruya PHENIX Upgrade mini-Workshop 19
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