Study of the Spatial Resolution and Muon Tomographic Imaging Properties of

Glass RPCs

Qite Li

Peking University

Knowledge is PowerSir Francis Bacon (1561-1626)

Nuclear Knowledge can be the Power of

• Peace• Happiness

• Fear• Frustration

●Uranium 90% (HEU)●Pu-239 93% (WGPu)

●26 kg HEU / 5kg WGPu ●11 cm / 6 cm box

Muon Tomography(MT)

2.3mrad 10mrad 20mrad ~1.1°

~GeV Muon 1/cm2/min

water Fe W10cm

MT Station Examples

Los Alamos (2003): Drift Tubes

Science and Global Security 16 (2008)37–53

INFN : CMS Muon Barrel Chambers

Nucl. Inst. and Meth. A 604 (2009) 738-746.

FIT : Triple GEMs

Nucl. Inst. and Meth. A 652 (2012) 16-20

Requirements of Detectors for MT

• Large Area (~1m2)• High Detction Efficiency (>90%)• High Spatial Resolution (<1mm)

• Cost-effective

RPC

• Resistive Plate Chamber– R. Santonico(in 1980s)

• Large Area• Good Time Solution~1ns

• Acceptable Spatial Resolution– ~1cm

CMS Muon Trigger RPCs by PKU (200

2)

-HV

HV Graphite

Resistive Plate

Working Gas

Resistive Plate

Gruand GraphiteReadout Strips

RPC Brief View

Combination of RPC & Delay-line Readout

90% F134a+9% C4H10+1% SF6

50ml/Min

• Avalenche Signal

General Properties: Signals

• Avalenche +Streamer Signal

General Properties: Detection Efficiency

-HV

Streamer ProfileSigma 7.4±0.2mm

Avalanche ProfileSigma 2.2±0.1mm

Simulation ProfileSigma 2.40mm

Spatial Resolution Measurement

• Residual Method

• ΔX=X2-(X1+X3)/2

Spatial Resolution of Glass RPCs

mmFWHM

mmmm

XXXf

xx

x

xxxx

90.035.2

384.0470.0816.03

2

2

3)2

1()

2

1(

2/)(

223

221

222

2

312

Uniformity

-50mm~-25mm

Res=0.99 mm

-25mm~0mm

Res=0.89 mm

0mm~25mm

Res=0.82 mm

25mm~50mm

Res=0.94 mm

X Y and T readout in ONE RPC

X axis

0.79 mm (FWHM)

for one RPC

Y axis

1.97 mm (FWHM)

for one RPC

Preliminary

Preliminary

MT Station with three 2D-Glass RPCs12+2 channels

1P

2P

RPC 1

RPC 2

RPC 33P

Material

Imaging Result: Empty target

• Empty target

• Mean angle ~15 mrad– Position/Alignment err

or • ~8 mrad

– RPC box, framework• ~10 mrad

Preliminary

Imaging Result: Pb brick 1

• Pb brick 1• 15cm*5.5cm*3.5cm

Preliminary

Imaging Result: Pb brick 2

• Pb brick 2• 24cm*7cm*6cm

Preliminary

Conclusions

• Glass RPCs with LC Delay-line Readout– Simple structrue, stable performance– Efficiency 95~98%– Charge profile measurement

• <1mm(FWHM) in avalenche mode

– Ideal detectors for MT

• MT Station using three 2D-Glass RPCs– Preliminary Test (detection area: 20cm*20cm)– Sensitive to ~cm Pb

MT station with 4 RPCs 3D ImagingComing Soon

Thank You!

Email: Liqt@pku.edu.cn Gmail: Liqt1985@gmail.com

Supervisor: Prof. Yanlin YeEmail: yeyl@pku.edu.cn

Peking University, China