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RPC Performance vs Front-End: Evolution, Working Mode, and New Electronics

This workshop discusses the evolution of the Resistive Plate Chamber (RPC) technology and its working modes, with a focus on the comparison between streamer and saturated avalanche modes. The performance of front-end electronics is explored, along with the development of new high-performance electronics for RPCs operating in saturated avalanche mode.

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RPC Performance vs Front-End: Evolution, Working Mode, and New Electronics

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  1. RPC performance vs Front-End RPC 2010 Workshop GSI Darmstadt Feb 11th 2010 Roberto Cardarelli INFN Roma Tor Vergata

  2. RPC evolution vs Front-End • 1980 - The RPC was developed in streamer mode • 1993 - R. Cardarelli: “Operation of RESISTIVE PLATE CHAMBER with pure CF3Br”II International Workshop on RESISTIVE PLATE CHAMBERS IN PARTICLE PHYSICS AND ASTROPHYSICS, 15 giugno 1993 Roma2 • 1996 - R. Cardarelli, V. Makeev, R. Santonico: “Avalanche and streamer mode operation of resistive plate chamber”Nuclear Instruments & Methods A382 (1996) 470-474 • 1998 - P. Camarri, R. Cardarelli, ….R. Santonico: “Streamer suppression with SF6 in RPCs operated in avalanche mode”Nuclear Instruments & Methods A414 (1998) 317

  3. RPC signal with binary gas mixture

  4. RPC multi-avalanche • ∑iNi= ∑iN0ieαdiN ≈ 106 (saturated avalanche) - gas HV d1 d2 di +

  5. RPC prompt charge C2H2F4+C4H10+SF6 streamer +SF6 Saturated multi-avalanche Saturated avalanche

  6. RPC working mode vs charge,amplitude and pulse widht working mode prompt charge (pC) width (ns)amplitude (mV) Saturated avalanche 0.1-1 1-20.5-2.5 Saturated multi-avalanche 1-5 3- 52.5-10 Streamer 50-100 30-70100-300

  7. Total charge vs HV streamer Saturated multi-avalanche Saturated avalanche

  8. Front-end electronic vs different working RPC mode • Streamer : discriminator • Saturated multi-avalanche: preamp+discriminator • Saturated avalanche: preamp (highamplification and bandwidth) + discriminator IN THE END If the gas mixture and the gap of the RPC chamber are set, the front-end performance sets the working mode of the RPC

  9. Working mode for MRPC In the MRPC if we have in average only one ionization point in the gas gap, the only two working modes are: • Streamer • Saturated avalanche

  10. High performance electronics for saturated avalanche In order to increase the RPC rate capability we plan to: • decrease the gas amplification by working in saturated avalanche mode (lower HV) • realize new high performance front-end electronics • optimize the gap width/number for high rate operation

  11. New electronics performance • Sensitivity 2 mV/fC • Noise 2 fC RMS • Latch capability 100 pS • B.W. 50 MHz • Power consumption 6 mW • Vth > 15 mV • Qth > 6 fC • Tunable input impedance from a few Ohm to 100 Ohm (maximum)

  12. Simulated amplifier pulse response

  13. CR test with of one RPC equipped with the new front-end electronics HV trigger RPC1 RPC2 Amp. RPC3 RPC4

  14. Efficiency versus HVRED: Amplified signal with Vth = 30 mV (new front-end electronics)BLACK: Unamplified signal with Vth = 1.5 mV (standard ATLAS front-end electronics)At fixed efficiency the new FE works 500-600 V lower 500 V

  15. Average total charge delivered in the gas vs. operating voltage.At the working efficiency there is a gain of about 10 in the delivered charge Saturate multi-avalanche (ATLAS like) New fron-end

  16. Rate capability (GIF) test of RPCs equipped with the new front-end electronics 1 m Scintillators trigger RPC rate = 7 kHz/cm2 from about 1.4 x 106 gamma cm-2 s-1 MDTs Gamma source 18 x 18 cm2 RPC

  17. kHz HV RPC single counting rate (source ON)

  18. HV RPC absorption current (source ON) uAmp

  19. CR efficiency with source ON and OFF Acceptance x Efficiency Source OFF 100 V Source ON (7 kHz/cm2) HV

  20. Conclusions • New RPC Front-End electronics has been developed • The charge threshold is about a factor 10 lower with respect to the present ATLAS Front-End. • The rate capability has been increased accordingly. • An RPC under test at the GIF facility at CERN is operating at full efficiency under full exposure from a 137Cs gamma source at the counting rate of 7 kHz cm-2

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