020703 DHCAL

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. Choice of RPC working conditions 2. RO electronics 3. R&D plans 4. Proposal for joint mech. structure

Choice of RPC working conditions: 

Choice of RPC working conditions RPCs with 0.8,1.2, 1.6 and 2.0 gas gaps were tested in saturated avalanche and streamer 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 tests: 

RPC tests Set-up at 18T channel 5 GeV/c h+ beam RPC samples - 0.8, 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

Conclusion for working conditions: 

Conclusion for working conditions 1. RPCs in avalanche mode are in favor to be used for FLC DHCAL 2. Working conditions: -gas gap 1.2 -1.6 mm - gas mixture TFE/IB/SF6 - average induced charge ~4 pC (107 e) - efficiency ~ 99% - pad multiplicity ~ 1.4-1.5 - rate capability < 100 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)

Conclusion for working conditions: 

Conclusion for working conditions V. Gapienko (IHEP) Geant3 simulation of DHCAL response

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 Q ~ 107 e 2 adj pads Mean 2.8 pC RMS 1.6 pC Mean 1.47 RMS 0.58

RPC in streamer mode: 

RPC in streamer mode Typical Q and M distributions, 200 V above knee 1.2 mm gap, TFE/Ar/IB=80/10/10 FWHM=20% RMS/Q=0.6

Comparison of avalanche and streamer modes: 

Comparison of avalanche and streamer modes Eff vs M streamer Ar10 mix 100 mV thr 300 mV thr N210 mix 100 mV thr Avalanche - solid line There is some region for low M (1.1-1.2) with eff~95% comparing with avalanche mode

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)

RPC design for DHCAL: 

RPC design for DHCAL

RO electronics: 

RO electronics General scheme for 64 channel read out Two parts: Conditioning (analog) FPGA (digital)

RO electronics: 

RO electronics Requirements for FLC - All FEE should be on board - One channel < 1 cm2 - Anode PCB with pads should be multi layer PCB

RO electronics: 

RO electronics Steps for design and usage

RO electronics: 

RO electronics Two versions for conditioning 1) IHEP version Preamp(IC)+comparator(IC)+gate(IC) each single channel IC 2) Minsk version special 8 channel chip included preamp, amp and comparator (very sensitive ~0.2 A)

RO electronics: 

RO electronics IHEP version, threshold > 0.5 mV Preamp, 10x Comp, 5 mV Gate, 100-300 ns TTL pos signal for FPGA Was tested successfully in Dec02 beam run as separate board (approach A)

RO electronics: 

RO electronics Test of IHEP version with RPC signals using  source Comparison of counting rate with old, calibrated FEE 1 mV threshold is achieved

RO electronics: 

RO electronics Test of Minsk version with RPC signals using  source Comparison of counting rate with old, calibrated FEE 0.5 mV threshold is achieved

RO electronics: 

RO electronics IHEP version single 6 layer anode PCB for 64 channels Layer meaning 1. Anode pads 2. Shield GND 3. Signal CMOS lines 4. Power layer 5. Shield analog GND 6. Component layer FPGA on the same PCB, out of RPC ALTERA EP1K50 is used as FPGA All components (ICs) in SOT-23-5 packages

RO electronics: 

RO electronics Preliminary tests do not allow to reach lowest threshold - below 5 mV threshold it is channel generation due to the cross talk from the gate with TTL signal to pads. IHEP version single 6 layer anode PCB for 64 channels

RO electronics: 

RO electronics 1. Play with IHEP version (single PCB) to find possible minimal threshold for one RPC plane (64 channels) 2. Use the two PCB approach further - to simulate chamber PCB with signal transportation to find proper impedance etc - to design FEE PCB based on Minsk version 3. For beam tests of 20 layer electromagnetic cal (Dec03) use Minsk version of two PCB approach 4. It is proposed to use for the 1 m3 prototype also two PCB approach. It is planned together with Minsk to design special 16 simplified chip based on on the current Minsk 8 channel analog chip. PLANS

R&D plans: 

R&D plans December 2003 Beam tests of the 20 layer digital ‘E/H' calorimeter with the 64 channel small RPC planes and the 2/4 cm steel sampling June 2004 We are ready for Production and assembly of RPC planes for the 1 m3 DHCAL prototype

R&D plans: 

R&D plans  R=4.5 cm 98% trans. cont.  Digital ‘E/H’ calorimeter with 20 layers sampling: 2/4 cm steel + 0.65 cm RPC plane sensitive area 9x9 cm2 ( 8x8 pads of 1x1 cm2, 1 mm spacing) GEANT3 simulation of transverse containment pe=1,10,40 GeV/c Trans. cont. Diff. distr.

Proposal for joint mech. structure: 

Proposal for joint mech. structure N 1 2 3 4 5 6 7 8 9 10   11 12 13 Item Shape Number of layers Material of absorber Thick of absorber Tolerance for thick Tolerance for flatness Support plate Gap active detector Transverse active area Boarders proposal Rectangular 38 SS ? 20 mm –tsup.pl. 0.1 mm 0.1           mm/m SS, tsup.pl.=2 mm 6-7 mm 500x1500 mm2 top= mm, bottom= mm, left= mm, right= mm Comment Insert to magnet Insert to magnet