MRPC for STAR MTD upgrade

Yongjie Sun

Center of Particle Physics and TechnologyUniversity of Science and Technology of China

2010-10-23 STAR Regional Meeting, Ji'nan, China 2

Index

Introduction R&D on Long-strip MRPC Summary

2010-10-23 STAR Regional Meeting, Ji'nan, China 3

1. Muons: Penetrating Probes

A large area of muon telescope detector (MTD) at mid-rapidity, allows for the detection of

• di-muon pairs from QGP thermal radiation, quarkonia, light vector mesons, possible correlations of quarks and gluons

as resonances in QGP, and Drell-Yan production

• single muons from their semi- leptonic decays of heavy flavor hadrons

• advantages over electrons: no conversion, much less Dalitz decay contribution, less affected by radiative losses in the detector

materials, trigger capability in Au+Au

Z. Xu, BNL LDRD 07-007;L. Ruan et al., Journal of Physics G: Nucl. Part. Phys. 36 (2009) 095001

2010-10-23 STAR Regional Meeting, Ji'nan, China 4

MTD Concept of Design

A detector with long-MRPCs covers thewhole iron bars and leave the gaps in- between uncovered. Acceptance: 45% at ||<0.5

117 modules, 1404 readout strips, 2808 readoutchannels

Long-MRPC detector technology, HPTDCelectronics (same as STAR-TOF)

2010-10-23 STAR Regional Meeting, Ji'nan, China 5

The success of MRPC for STAR TOF

Muon Detector

Time resolution <100ps Efficiency 90%High granularity

2010-10-23 STAR Regional Meeting, Ji'nan, China 6

The multiplicity of muon tracks is quite low To save electronics channels Read out at two ends

Mean time Eliminate the position along the strip Time difference Position information

Easy to build for large area coverage detector

MRPC with Long Strips

2010-10-23 STAR Regional Meeting, Ji'nan, China 7

Gas gaps: 10 x 0.25 mm, in 2 stacks

Glass plates: 0.71 mm

anode

2. First prototype design

Size: 950 x 256 mm2

Read out strip: 25 mm wide, 4 mm gaps between strips

Active area: 870 x 170 mm2

2010-10-23 STAR Regional Meeting, Ji'nan, China 8

Some photos

2010-10-23 STAR Regional Meeting, Ji'nan, China 9

Trigger area: 20 x 5 cm2

Time reference (T0) TOF MRPC was used t

o get 6 segments along the strip.

Gas: 95% Freon + 5% iso-butane HV=±6.4kV

LMRPC

Cosmic ray test

Telescope setup

2010-10-23 STAR Regional Meeting, Ji'nan, China 10

Left end ADC Spectrum Right end ADC SpectrumADC ch ADC ch

Trigger area and ADC spectrum

Cosmic ray test

Trigger area:20 x 5 cm2

STAR TOF MRPC PAD:3.15 x 6.1

cm2

Scheme of the trigger

2010-10-23 STAR Regional Meeting, Ji'nan, China 11

HV plateau

Cosmic ray test

2010-10-23 STAR Regional Meeting, Ji'nan, China 12

signal propagation velocity

Cosmic ray test

TOF MRPC

6 trigger positions along the strip

Time difference of 2 ends vs. position

V-1~59.6±4.9 ps/cm

2010-10-23 STAR Regional Meeting, Ji'nan, China 13

center of the strip

One end of the strip

T-A correlation

T-A correction & Time resolution

Cosmic ray test

2010-10-23 STAR Regional Meeting, Ji'nan, China 14

MWPC5MWPC1 MWPC2

MWPC4

TOF1

252” 73”

TOF2

72” 164”449”

LMRPC

GEMsMWPC3

191”56 3381

TOF370”

Upper stream

Down stream

C1, C2

Beam Energy: 32 GeV

FNAL Beam Test (T963)

Beam test setup

2010-10-23 STAR Regional Meeting, Ji'nan, China 15

Efficiency plateau

FNAL Beam Test (T963)

Time resolution

2010-10-23 STAR Regional Meeting, Ji'nan, China 16

FNAL Beam Test (T963)

Using the tracking, we get the signal propagation velocity:

~ 60ps/cm

The half time difference of 2 ends of a strip:

σΔT/2 ~ 1.1 channel (55ps)

Spatial resolution: ~ 1 cm

Spatial resolution

2010-10-23 STAR Regional Meeting, Ji'nan, China 17

Running in STAR

Run 7 & Run 8

Run 9 & Run 10

2010-10-23 STAR Regional Meeting, Ji'nan, China 18

Run 10 Performance: Time and Spatial Resolution

Cosmic ray trigger:

Total resolution: 109 ps

Start resolution (2 TOF hits): 46 ps

Multiple scattering: 25 ps

MTD intrinsic resolution: 96 ps

System spatial resolution: 2.5 cm, dominated by multiple scattering

L. Li, UT Austin

σ: 109 ps

σ: 2.5 cm

pure muonsaverage pT: ~6 GeV/c

From Lijuan Ruan’s talk at MTD review Sep. 17, 2010

2010-10-23 STAR Regional Meeting, Ji'nan, China 19

Run 9 Performance: Time Resolution

L. Li, UT Austin

σ: 142 ps Include muons from pion, kaon decays and punch-through hadrons

Muon average pT: ~2.5 GeV/c

Total resolution: 142 ps

Start resolution (start detector with TOF electronics readout): 81 ps

Multiple scattering: 70 ps

MTD intrinsic resolution: 94 ps

From Lijuan Ruan’s talk at MTD review Sep. 17, 2010

2010-10-23 STAR Regional Meeting, Ji'nan, China 20

3. Prototype of “real size”

“real size” module: active width ~ 52 cm12 strips: ~4 cm wide Single stack: 6(5) × 0.25 mm gaps

2010-10-23 STAR Regional Meeting, Ji'nan, China 21

Structure — side view

inner glass = 874

Licron electrode = 882

outer glass / honeycomb = 890

PC board = 915

Licron electrode = 551outer glass / honeycomb = 559

PC board = 580

38 6

inner glass = 543

Gas gaps: Prototype I: 250μm × 6Prototype II: 250μm × 5

2010-10-23 STAR Regional Meeting, Ji'nan, China 22

HV plateau of Prototype I (6 gaps)

Adding 2% of SF6 Efficiency: little change Time resolution: improved a lot Quenching the streamer

2010-10-23 STAR Regional Meeting, Ji'nan, China 23

Charge spectrum@±7600V

With more SF6, less streamer achieved.

no SF6 2% SF6 5% SF6

2010-10-23 STAR Regional Meeting, Ji'nan, China 24

Noise rate (Hz/strip)

HV=8000V, Vth=30mV (R134a:C4H10:SF6=93:5:2)

Strip No.

1 2 3 4 5 6 7 8 9 10 11 12

Left 479 253 407 359 310 274 255 252 321 390 259 346

Right

526 280 326 303 163 235 320 266 377 400 280 313

• With HV filter:HV

(+/-) 10MΩ0.5nF

LMRPC

Equivalent to < 1.5 Hz/cm2, comparable to TOF MRPC

2010-10-23 STAR Regional Meeting, Ji'nan, China 25

Prototype II with 5 gaps

Efficiency > 90% over 6300 V Time resolution comparable to Prototype I. (without SF6) Electric field:

kV/cm8.1005cm025.0

2kV3.6

kV/cm7.98

6cm025.0

2kV4.7

5-gap: 6-gap:

2010-10-23 STAR Regional Meeting, Ji'nan, China 26

The first Long-strip MRPCs (10-gap) show very good performance and

were successfully running at STAR from Run7 to Run10. The cosmic ray test :

time resolution: around 70 ps; detection efficiency: higher than 95%.

T963 beam test at FNAL: spatial resolution: less than 1 cm. time resolution and detection efficiency similar to cosmic test

Performance running at STAR: Time resolution <100ps, spatial resolution ~2.5cm

The performances of both “real size” LMRPCs are good enough for the MTD requirements.

Current status: One has been shipped to UT and the other will be shipped out soon. Both to be installed in STAR and running in Run11.

The MTD MRPC mass production project has been approved by NSFC and will start from 2011.

4. Summary

Thank You ！