November 5, 2004 V.Ammosov ITEP-Moscow, Russian CBM meeting
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IHEP possible participation in CBM TOF system
Vladimir Ammosov
Institute for High Energy Physics
Protvino Moscow region, Russia
November 5, 2004 V.Ammosov ITEP-Moscow, Russian CBM meeting
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CBM challenge for TOF
Item value commentTime resolution ~50 ps for R&D ~80 ps for system Rate capability ~105 Hz/cm2 High granularity 4 cm2
and large scale ~ 100 m2
It is intended to use RPCs in the CBM TOF system.Currently there are no real TOF RPC systems with such
time resolution and rate capability.IHEP group is interested to participate in R&D challenge
and TOF system construction
November 5, 2004 V.Ammosov ITEP-Moscow, Russian CBM meeting
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IHEP TOF group
We were/are busy with RPCs since 1993- ATLAS muon system- HARP TOF system- R&D for hadron calorimer for LC
Group comprises 4 hardware physicists 1 software phys. 2 engineers 2 technicians
November 5, 2004 V.Ammosov ITEP-Moscow, Russian CBM meeting
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Possible solution – multigap RPC
- 2x(2x0.3 mm) chamber - thin (0.6 mm) glass plates- read out in the middle- gas mixture TFE=C2H2F4/IB/SF6=80/5/5 8 ion.cl./mm-saturated avalanche mode IB – quencher SF6 – streamer suppressor <Q> ~1 pC
Reason for multigapt ~ 1/Et ~ 1/Ngap
HARP example
November 5, 2004 V.Ammosov ITEP-Moscow, Russian CBM meeting
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HARP R&D resultst vs pad size
HV plateau ~ 200 V t (ps) = 70+.26ps/cm2 x S for St (ps) = 71+.13ps/cm2 x S for el sum
November 5, 2004 V.Ammosov ITEP-Moscow, Russian CBM meeting
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Obtained eff ~ 98-99% OK
Obtained t ~ 160-180 psis worse
than R&D 130 ps(~sqrt (2) )
HARP RPC TOF system
November 5, 2004 V.Ammosov ITEP-Moscow, Russian CBM meeting
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Our current R&D vision
1 RPC TOF option Intend to continue searching for plastics, glass, enamels
with proper resistivity to reach rate capability up to ~105 Hz/cm2
with required signal, efficiency and noise levels Joint work with INR, ITEP and Western groups within the INTAS-GSI
project for CBM TOF system
2 Si PM as back up TOF forward option Intend to study possibility to reach 50 ps time resolution with scintillator+SiPM
November 5, 2004 V.Ammosov ITEP-Moscow, Russian CBM meeting
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Possible participation in TOF construction
Up to now IHEP still has some infrastructure to- construct RPC detectors- test RPC detectors
We are interested to contribute to these items sizeably
Furthermore participation in design and construction of front-end electronics can be considered
November 5, 2004 V.Ammosov ITEP-Moscow, Russian CBM meeting
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RPC R&DPestov glass
Cathode – SSAnode - window glass (WG) ~8·1012 ·cm or - Pestov glass (BG) ~4·1010 ·cm
Sat. avalanche modeTFE/IB/SF6 = 90/5/5Gap = 1.2 mm
Was tested in 5 Gev h+ beamat IHEP, Protvino
November 5, 2004 V.Ammosov ITEP-Moscow, Russian CBM meeting
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RPC R&DPestov glass
Comparison of efficiency
Thr. 0.6 mVRate 50 Hz/cm2
Level of eff. ~ 90%
Some drop of eff. for WG
Pestov glass
WG
November 5, 2004 V.Ammosov ITEP-Moscow, Russian CBM meeting
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RPC R&DPestov glass
Comparison of average charge
Thr. 0.6 mVRate 50 Hz/cm2
Same level of charges
Drop of charge for WGat high HV
Pestov glass
WG
November 5, 2004 V.Ammosov ITEP-Moscow, Russian CBM meeting
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RPC R&DPestov glass
Comparison of noise
Usual WG RPC with c&a = WG, gap=1.2 mm
Higher level of noise with SS cathode
Higher noise of Pestov glassin working region
Pestov glass
WG
usual WG RPC
November 5, 2004 V.Ammosov ITEP-Moscow, Russian CBM meeting
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RPC R&DPestov glass
Comparison of rate
Thr. 0.6 mV
Pestov glass rate capability ~ 5 kHz/cm2practical maximum whichis available with beam
Pestov glass
usual WG RPC
WG
November 5, 2004 V.Ammosov ITEP-Moscow, Russian CBM meeting
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RPC R&DPestov glass
Comparison of resistivity behavior vs HV
Resistivity is not constant for bakelite and Pestov glass
Window glass
Bakelite
Pestov glass
November 5, 2004 V.Ammosov ITEP-Moscow, Russian CBM meeting
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RPC R&DEpoxy enamel
Cathode and anode are epoxy enamel ETAL-47 with ~1010 ·cm 0.4 mm thick
Sat. avalanche modeTFE/IB/SF6 = 90/5/5Gap = 0.55 mm
Was tested in 5 Gev h+ beamat IHEP, Protvino
November 5, 2004 V.Ammosov ITEP-Moscow, Russian CBM meeting
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RPC R&DEpoxy enamel
Efficiency vs HV
Thr. 1.25 mV
Eff. is ~90% which is reasonablefor 0.55 mm gap
November 5, 2004 V.Ammosov ITEP-Moscow, Russian CBM meeting
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RPC R&DEpoxy enamel
Comparison of noise
Noise for enamel is rather larger
at working HV point 4.9 kVnoise for enamel ~ 200 Hz/cm2
November 5, 2004 V.Ammosov ITEP-Moscow, Russian CBM meeting
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RPC R&DEpoxy enamel
Comparison of rate capability
for enamel up to 10 kHz/cm2 – maximal beam intensity which was available
for usual glass RPC ~100 Hz/cm2
enamel
Usual 1.2mm gapWG RPC
November 5, 2004 V.Ammosov ITEP-Moscow, Russian CBM meeting
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Conclusion
1 RPC TOF option Intend to continue searching for plastics, glass, enamels with proper resistivity to reach rate capability up to ~106 Hz/cm2 with required signal, efficiency and noise levels2 Si PM back up TOF option for small Intend to study possibility to reach 50 ps time resolution with scintillator+SiPM
November 5, 2004 V.Ammosov ITEP-Moscow, Russian CBM meeting
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Si PM option for TOF
P. Buzhan et al., ICFA
Instrum.Bull.23:28-41,2001
SiPM size ~ 1, 9 mm2, ~ 1000 cells of 30x30 2
Max light sensitivity at 570 nm, overall ~14%Each cell works in Geiger mode independently, gain ~106
Developers in Russia: Pulsar + MEPhI (B. Dolgoshein) CPTA (V.Golovin) Dubna (Z.Sadygov)
November 5, 2004 V.Ammosov ITEP-Moscow, Russian CBM meeting
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Si PM option for TOF
For cell intrinsic A/A ~0.1 1,2,3,4 ph. electrons are seen
recovery time <100 ns >10 MHz rate capability
intrinsic t = 100 ps/sqrt (Ncell)
Noise for 1 cell (ph.e.) ~1 MHz,decrease with Ncell increase
t,ps
Ncell
P. Buzhan et al., ICFA
Instrum.Bull.23:28-41,2001