REWARD - Semiconductor Detectors as Radiation Monitors FP7-SEC-2011.1.5-1 / 284845 1

Ulrich ParzefallPhysikalisches Institut, Albert-Ludwigs-Universität, Freiburg, Germany

On behalf of the REWARD Consortium

http://www.reward-project.eu/consortium.html

REWARDWide Area Radiation

Surveillance with Semiconductor Detectors

Partners

Research & Education

Industry End Users

SMELarge

Partners

External Experts

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Introduction• The REWARD idea• Radiation detectors:

Gamma and Neutron systems• Status

Outline

• XIE GmbH is a SME from Freiburg, Germany

• S&C is a SME from Barcelona, Spain

• Vitrociset is a large Italian Company

• Edisoft is a large Portuguese Company

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The REWARD Partners: Industry

• CSIC is the Spanish Research Council of Scientific Investigations

• University in Freiburg, Germany

• ITN is the Portuguese Nuclear and Technological Institute in Lisbon

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The REWARD Partners: Academia

• Civil Protection of the Region of Campania, Italy

(We also work with the Rome Fire Brigade)

• Spanish Civil Protection from Catalunya

• Spanish “Guardia Civil” from Catalunya

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The REWARD Partners: End Users

• Radiation monitoring network: small autonomous mobile units mounted on cars

• Semiconductor sensors for gamma and neutron detection

• (Cd,Zn)Te (CZT) gamma sensor for precise energy measurement (isotope ID)

• Si detector with converter for thermal neutrons

• Geolocation from GPS receiver • Secure communications unit

– Choice of TETRA, GSM (UMTS, …)

• Data get send to and processed in Central Control Room in real time

• Goals: Obtain radiation map (background mapping), discover potential radioactive threats

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The REWARD Concept

Remote Control Station

• Decade of CZT expertise in Freiburg Materials Research Centre (FMF) and spin-off company X-Ray Imaging Europe (XIE)

• CZT System designed for autonomous long-term gamma spectroscopy

• Joint Project with Federal Ministry of Radiation Protection (German “BFS”)

• BFS operates a nationwide network of radiation monitors

• CZT Unit placed on top of Black Forest Mountain near Freiburg

• Successful data taking for many months

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Roots: First Freiburg CZT Radiation Monitoring System

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Long-Term Spectrum from BFS CZT Prototype

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Initial Prototype Gamma Detector System

The core: Coplanar Grid detector

• Two (Cd,Zn)Te sensors (19 x 19 x 5 mm3) in coincidence• FE Read Out Electronics (shielded) and cooling nearby

Sensors

Peltier cooler

Heatpipe

Preamplifiers

• (Cd,Zn)Te sensor on PCB biasing board

• Similar to BFS system• Coplanar Grid anode

structure (removal of hole current contribution)

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2nd Prototype: Gamma Detection System

Coplanar GRID detector

• 2x (Cd,Zn)Te sensors (10 x 10 x 10 mm) in coincidence

• MCA up to 4 MeV (1 keV energy binning)• Temperature stabilization: 20˚C with Peltier cooling• Ideal biasing voltages have to be determined for each

detector• One prototype built, currently testing

Picture of one (Cd,Zn)Te sensor on the PCB biasing board

Sensors

Dissipation box

PCB board forpreamplifiers

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Dissipation box

ConnectorsThermalInsulation

2nd Prototype: Gamma Detection System

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Cs-137 Energy Spectrum, measured with a 1 cm³ CZT CPG at Room Temperature

2nd Prototype: Gamma Detection System

Energy resolution: 1.6%

Reward Project: Geant4 Simulation Results of the Gamma Detection System. FP7-SEC-2011.1.5-1 / 284845

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Implementation of the Gamma Detector in Geant4

XY

Z

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Simulated Photopeak Detection Efficiency

0 1 2 3 40,1

1

10

100

Abs

olut

e E

ffici

ency

(%

)

Source Energy (MeV)

Source at Z axis Source at Y axis Source at XYZ

2x CZT 10x10x10 mm3

0 1 2 3 40,1

1

10

1002x CZT 19,5x19,5x5 mm3

Abs

olut

e E

ffici

ency

(%

)

Source Energy (MeV)

Source at Z axis Source at Y axis Source at XYZ

Determination of photo peak detection efficiency for two CZT sensors working in coincidence for different incident angles of mono-energetic gamma rays

Photo Peak Detection Efficiency

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Neutron Detector System (CNM Barcelona)

REWARD detector boards with 4 silicon sensors and electronic components.

Prototype sensor with 10B layer

Silicon wafer with sensors at CNM

• Neutron detection based on thin silicon sensor and 10B converter layer for slow neutrons

• Reduced thickness to reduce gamma rates

• Si sensor in novel 3D-type layout to increase area and hence efficiency

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• First prototype of neutron detector module

• 4 boards (no sensors mounted) • Central PE block serves as

moderator to increase rate of slow neutrons

Neutron Detector System (CNM Barcelona)

• Neutron detector board with 4 silicon sensors and electronic components

• Several boards used simultaneously to increase efficiency

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Reference Test Case: 137Cs

• „Goiania Incident“ used as one reference scenario

• Radiotherapy 137Cs source stolen from abandoned hospital in Brazil 1987

• Opened, handled and 137Cs powder touched by several people (who were unaware of any risks)

• Nuclear hazard recognised as such after 16 days

• 4 fast deaths, 249 people significantly contaminated, enormous clean-up operation

• Goiania Model source: 5.1 x 1013 Bq of 137Cs behind a shield of Pb, Cu, W, steel Im

ages

fro

m I

AE

A R

epor

t www-pub.iaea.org/mtcd/publications/pdf/pub815_web.pdf

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Reference Test Case: Nuclear Warhead

• Nuclear Warhead scenarios from non-classified sources

• Fetter, S. et al. “Detecting Nuclear Warheads”. Science & Global Security, 1990, Volume 1, pp.225-302.

• Based on typical weapons grade Uranium or Plutonium cores

• Surrounded by tamper and shielding

0 1 2 3 4100

101

102

103

104

105

Co

un

ts

Energy (MeV)

BlackForest

0 1 2 3 4100

101

102

103

104

105

Cou

nts

Energy (MeV)

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Gamma Background

Spectrum (Lab conditions) Spectrum from the Black Forest

Background Experimental Measurements

Measuring time: 140 hours Measuring time: 196 hours

Laboratory Black Forest

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0 1 2 3 40

1

2

3

4

5

6

Cou

nts

Energy (MeV)0 1 2 3 4

0

1

2

3

4

5

6

Cou

nts

Energy (MeV)

Spectrum (Lab conditions) Spectrum from the Black Forest

Background Experimental Measurements

Sampling time: 30 seconds Sampling time: 30 seconds

Laboratory~ 180 counts

Black Forest~ 190 counts

Gamma Background

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Expected System Performance: 137Cs

• Simulated spectra for Goiania type scenario• CZT System 1 (5, 10) m away from source, running for 30s• Can very easily see signal and discriminate against

background, and identify the 137Cs from the 662keV line

0,0 0,1 0,2 0,3 0,4 0,5 0,6 0,7100

101

102

103

104

105

106

107

108

109

Cou

nts

Energy (MeV)

1 meter

5 meters

10 meters

137Cs with Tungsten shielding

Background ~ 190 counts

0,0 0,1 0,2 0,3 0,4 0,5 0,6 0,7100

101

102

103

104

105

106

107

108

109

C

ount

s

Energy (MeV)

Background ~ 190 counts

10 meters

5 meters

1 meter

137Cs with Stainless Steel shielding

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Expected System Performance: Nuclear Warhead

• Simulated spectra for weapons grade Plutonium scenario• CZT System 1 m away from source, running for 30s• Difficult to see signal above background• Situation even worse for weapons grade Uranium

0 1 2 3 40

1

2

3

4

5

Cou

nts

Energy (MeV)

WgPu with DU tamper

Background ~ 190 counts

0 1 2 3 4 50

1

2

3

4

5

Cou

nts

Energy (MeV)

WgPu with Tungsten tamper

Background ~ 190 counts

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• Novel silicon sensors, (Cd,Zn)Te CPG sensors plus IT and

communication technology fused to create radiation detection and

monitoring network• First prototype put together this summer• Commercialisation possible (and desired!)• System well suited to e.g. Goainia scenario. • Nuclear warheads more difficult to detect - would need extra info

from neutron system• Many other use feasible case:

• Monitoring after Fukushima-type incident• Background mapping

Conclusions & Outlook

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BACKUP ONLY FROM HERE

Advertisement: Freiburg is looking to recruit •PhD student to work on Si detectors (ATLAS Tracker Upgrade) Contact Ulrich.Parzefall@cern.ch for details and/or informal enquiries