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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
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• 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
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• 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
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• 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
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• 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
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• 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%
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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
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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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