Ammosov RPC IHEP

Status of RPC R&Dfor DHCALin IHEP: 

Status of RPC R&D for DHCAL in IHEP Vladimir Ammosov Institute for High Energy Physics Protvino Moscow region, Russia

Content: 

Content 1. RPC design for DHCAL 2. Tests of RPCs - in avalanche mode - in streamer mode 3. Comparison of operation modes 4. Conclusion

RPC design for DHCAL: 

RPC design for DHCAL

RPC design for DHCAL: 

RPC design for DHCAL

RPC design for DHCAL: 

RPC design for DHCAL Dead zones

RPC tests: 

RPC tests Set-up at 18T channel 5 GeV/c h+ beam RPC samples - 1.2, 1.6, 2.0 gaps - 1013 cm window glass - 16 pads of 1x1 cm2 - in tight box Trigger S1S2S3S4 for 2x2 cm2 area Di - preamp+disc

RPC tests: 

RPC tests Gas mixtures RPCs were tested in saturated avalanche and trigger modes For both modes TetraFluoroEthane (TFE) based mixtures were used TFE = freon 134A = C2H2F4 ~ 8 ionizations/mm Saturated avalanche mixtures = TFE/IB/SF6 IB = Iso-C4H10 as quencher, IB fraction = 5% SF6 as streamer suppresor, SF6 fractions = (2-5)% Streamer mixtures = TFE/IB/Ar or N2 IB = Iso-C4H10 as quencher, IB fraction= (5-20)% Ar/N2 as streamer developer, fractions = (2-20)%

RPC in avalanche mode: 

RPC in avalanche mode 1.2 mm gap RPC eff, <m> vs HV - 2% and 5% of SF6 For 2.2 mV Knee 8.2 kV 8.6 kV V 0.6 kV 0.6 kV Thresholds  - 0.6 mV  - 2.2 mV  - 5.0 mV 2.2 mV is best threshold eff >99% low <m> ~ 1.4

RPC in avalanche mode: 

RPC in avalanche mode 1.6 mm gap RPC eff, <m> vs HV - 2% and 5% of SF6 For 2.2 mV Knee 8.8 kV 9.8 kV V 0.8 kV 0.8 kV Thresholds  - 0.6 mV  - 2.2 mV  - 5.0 mV 2.2 mV is best threshold eff >99% low <m> ~ 1.4

RPC in avalanche mode: 

RPC in avalanche mode 2.0 mm gap RPC eff, <m> vs HV - 2% and 5% of SF6 For 2.2 mV Knee 10.0 kV 11.4 kV V 0.8 kV 0.6 kV Thresholds  - 0.6 mV  - 2.2 mV  - 5.0 mV 2.2 mV is best threshold eff >99% low <m> ~ 1.4

RPC in avalanche mode: 

RPC in avalanche mode Typical Q and m distributions 1.2 mm, 2% SF6, 8.4 kV - working point, 2.2 mV thr Mean 2.8 pC RMS 1.6 pC Mean 1.47 RMS 0.58 Q ~ 107 e 2 adj pads

RPC in avalanche mode: 

RPC in avalanche mode <Q> and Q behavior, 2% SF6 1.2 mm 1.6 mm 2.0 mm For all gaps Q/<Q> ~ 1    knee

RPC in avalanche mode: 

RPC in avalanche mode Eff and <m> vs pad spacing No any prominent dependence for 0.3 -1.0 mm spacings

RPC in avalanche mode: 

RPC in avalanche mode Efficiency as a function of trigger position between two adjucent strips

RPC in avalanche mode: 

RPC in avalanche mode <m> vs anode thickness Should be as small as possible

RPC in avalanche mode: 

RPC in avalanche mode Eff and <m> vs beam incident angle No any prominent dependence for 900 - 450 angles

RPC in avalanche mode: 

RPC in avalanche mode Noise is increased as function of E 1.6 mm - ~0.2 Hz/cm2 1.2 mm - ~0.5 Hz/cm2  - 1.2 mm  - 1.6 mm  - 2.0 mm 1.6 mm knee 1.2 mm 2.0 mm Noise

RPC in streamer mode: 

RPC in streamer mode 1.2 mm gap, thr > 50 mV efficiency ~95% No 100% avalanche -streamer transition for any gas mixtures with Ar/N2 additions

RPC in streamer mode: 

RPC in streamer mode 1.2, 1.6, 2.0 mm gaps, thr > 50 mV efficiency ~95% No 100% avalanche -streamer transition for any gas mixtures with Ar/N2 additions Not lucky with streamer  also Q/<Q> ~ 0.6 as for avalanche

RPC in streamer mode: 

RPC in streamer mode Typical Q distributions on knee 1.2 mm 1.6 mm

RPC in streamer mode: 

RPC in streamer mode Eff ~95% and <m> ~ 1.4-1.5 for 200 mV thr 1.2 mm gap

RPC in streamer mode: 

RPC in streamer mode 1.2, 1.6, 2.0 mm gaps, thr > 50 mV Noise ~0.1 Hz/cm2 for 1.2 and 1.6 mm

Comparison of avalanche and streamer modes: 

Comparison of avalanche and streamer modes Rate capability streamer <4-5 Hz/cm2 avalanche <300 Hz/cm2 It is hard to work in streamer mode even for usual beam conditions Streamer is suitable only for very low rates like e+e- FLC

Comparison of avalanche and streamer modes: 

Comparison of avalanche and streamer modes As example, for 1.2 mm gap

Comparison of avalanche and streamer modes: 

Comparison of avalanche and streamer modes Avalanche mode is preferable due to: 1. higher efficiency (>99%) 2. smaller charge deposition (~102) - no observed ageing effects - higher rate capability (~102)

R&D plans: 

R&D plans 1. RPC samples with 64 ch on board March03 2. 40x25 cm2 RPC plane with 512 ch on board ? April03 3. 1 m3 DHCAL prototype June04 - 40 RPC planes of 1 m2 - 400 000(100 000) channels for 1 m2 (0.25 m2) surface in collaboration with ANL, Dubna, Ecol Pol

Conclusion: 

Conclusion 1. RPCs in avalanche mode are in favor to be used for TESLA DHCAL 2. Working conditions: -gas gap 1.2 -1.6 mm - gas mixture TFE/IB/SF6 - average induced charge ~2 pC (107 e) - efficiency > 99% - pad multiplicity ~ 1.5 - rate capability < 300 Hz/cm2 - noise 0.2-0.5 Hz/cm2 3. RO electronics (thr>1-2 mV) is challenge ( cost should be at ~0.1 Euro level)