Heavy-ion collisions p-p data taking

heavy-ion collisions

p-p data taking

highly-saturated avalanche operation

preliminary studies with cosmic rays

• test on 50x50 cm2 RPC

• (Clermont-Ferrand laboratory)

• FEE thresholds set at 10 mV

• efficiency

• the shape of each signal is sampled each ns to study amplitude, timing and released charge:

• streamer comtamination

beam test setup (CERN: GIF + SPS-X5)

beam test: results (I)

• 4 efficiency calculation methods:

• Coincidence Register
• tracking with DWC
• total
• core (higher beam irradiation rate)
• outer circle (lower beam irradiation rate)

• T/p correction:

• HVeff=HV0*(T/T0)*(p0/p)

• with T0=293.15 K, p0=970 mbar

beam test: results (II)

beam test: gas analysis

• during the test  analysis of the exhaust gas were performed both for streamer and maxi-avalanche operation of the RPC

ageing test setup (CERN GIF)

small prototype 1: ageing results

gas mixture modification

• we decrease the SF6 percentage to lower the working point

• beam test on 2 small prototypes (50x50 cm2) to check the performances with the gas mixture:

• 89.7% C2H2F4, 10% C4H10 + 0.3% SF6 – RH=50%

• to make a direct comparison with the gas mixture with 2% SF6:

• performances:
• cluster size: 1.8 (1 cm strip)
• time resolution: 1-2 ns
• efficiency: in all position the efficiency plateau reaches 95-96%
• no significant differences with respect to the gas mixture with 2% SF6
• working HV~10000-10100 V (800 V lower)
• streamer contamination <20%

small prototype 2: results

small prototype 3: results

efficiency plateaux

conclusions

Muon Trigger System

outline

• beam test (X5-SPS) on a pre-production RPC:

• RPC1, 70x270 cm2
• efficiency¤t, cluster size and gas analysis

• ageing test (GIF):

• RPC 50x50 cm2 (small prototype 1)

• beam test (X5-SPS)

• 2 RPC 50x50 cm2 (small prototype 2&3)

• ageing test (GIF):

• 2 RPC 50x50 cm2 (small prototype 2&3)

Signal amplitude with cosmics II

Signal amplitude with cosmics III

beam test, setup - FEE

instability problem (I)

• hp: local discharge

•  the temperature in correspondence of the discharge point should increase appreciably

instability problem (II)

streamer contamination

• % of streamer in the 25 tested positions at 3 different HVeff

• (10000 V, 10100 V and 10200 V)

• obtained with thresholds setting:

• X plane: 8 mV

• Y plane: 80 mV

• the distributions of these values are shown in next slide

streamer contamination distribution