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