Preparation of MTD production

Yongjie Sun

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

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Outline

Introduction Design of MRPC for MTD

The first prototype The “real size” prototype

Facilities for the mass production Summary and outlook

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1. STAR MTD

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

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The novel design of MTD

Iron bars as absorber Muon ID by combining

Track matching with MTD spatial resolution Energy loss in TPC Time-of-flight measurement time resolution

MRPC as detector Good timing: < 100 ps Spatial resolution: ~ 1 cm Cost-effective for large area coverage

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The success of MRPC for STAR TOF

Muon Detector

Time resolution <100ps Efficiency 90%High granularity

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The multiplicity of muon tracks is quite low Long strips save electronics channels Read out from 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

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Gas gaps: 10 x 0.25 mm, in 2 stacks

Glass plates: 0.71 mm

anode

2. Prototype design

Size: 950 x 256 mm2

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

Active area: 870 x 170 mm2

The first prototype was constructed in 2006 at USTC.

1.5 cm

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The considerations in the design

10 gaps: for better timing 2.5 cm wide strips: for better track mat

ching The size: limited by the pcb production

technics The edges: sufficient for uniform field a

nd HV protecting.

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Some photos

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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

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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

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HV plateau

Cosmic ray test

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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

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center of the strip

One end of the strip

T-A correlation

T-A correction & Time resolution

Cosmic ray test

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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

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Efficiency plateau

FNAL Beam Test (T963)

Time resolution

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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

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Running in STAR

Run 7 & Run 8

Run 9 & Run 10

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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

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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

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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)

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Prototype of “real size”

“real size” module: active width ~ 52 cm12 strips: 3.8 cm wide, 87 cm long, 0.6 cm in betweenSingle stack: 6(5) × 0.25 mm gaps

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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

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HV plateau of Prototype I (6 gaps)

The efficiency > 90% @ ±7300 V (Vth=30mV) Time resolution ~ 90 ps without SF6

SF6 is helpful for performance enhancement.

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Charge spectrum@±7600V

With more SF6, less streamer achieved.

no SF6 2% SF6 5% SF6

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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

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Prototype II with 5 gaps

Efficiency > 90% @± 6300 V Time resolution comparable to Prototype I.

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3. Facilities for mass production

The same clean room as for STAR TOF with controlled temperature and humidity.

Two new desks for big module construction.

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Electrode production

A separate room for glass cleaning and electrode spraying.

Clean the glass with hot steam and alcohol.

Graphite liquor will be used for painting the electrode.

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Cosmic ray test system

A new cosmic ray system has been setup. Trigger: 20 x 5 cm2

T0: <50 ps 16 TDC + 16 QDC VME based DAQ Gas: Freon + iso-C4H10 + SF6

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Manpower for production

3 professors, 1 lecturer, 2 pos-doc, 1 engineer and 3 graduate students.

2 technicians for module construction. 1 technician for electrode painting.

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

e 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.

The facilities are ready. Mass production can start soon after the final design is confirmed.

4. Summary

Thank You ！

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