Laboratorio di Rivelatori di Radiazione e Strumentazione Nucleare Laboratorio di Rivelatori di Radiazione e Strumentazione Nucleare Argomenti per tesi: (per studenti sia BIO che ELN) • Rivelatori di immagini X e gamma per applicazioni nella diagnostica medicale, nell’astronomia X su satellite e nello studio delle materia • Circuiti integrati per l’elaborazione di segnali da rivelatori di radiazione per applicazioni scientifiche e industriali Requisiti: • conoscenze di base di elettronica • attitudine/interesse all’attività sperimentale di laboratorio • buona volontà Dipartimento di Elettronica e Informazione - Sezione di Elettronica
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Laboratorio di Rivelatori di Radiazione
e Strumentazione Nucleare
Laboratorio di Rivelatori di Radiazionee Strumentazione Nucleare
Argomenti per tesi: (per studenti sia BIO che ELN)
• Rivelatori di immagini X e gamma per applicazioni nella
diagnostica medicale, nell’astronomia X su satellite e nello
studio delle materia
• Circuiti integrati per l’elaborazione di segnali da rivelatori
di radiazione per applicazioni scientifiche e industriali
Requisiti:
• conoscenze di base di elettronica
• attitudine/interesse all’attività sperimentale di laboratorio
• buona volontà
Dipartimento di Elettronica e Informazione - Sezione di Elettronica
Application of the SDD in g-ray spectroscopy and imaging
Advantages of SDDs with respect to other photodetectors:
• high quantum efficiency (~ 90 %) @ 565nm of CsI(Tl)• compact, mechanical robust• no statistical spread due to multiplication• low operating voltages • smaller sensitivity to bias and temperature variations • insensitivity to magnetic fields
g-ray
scintillator
SDD
Applications:
• medical imaging• gamma-ray astronomy• homeland security• nuclear physics experiments
Anger Camera based on SDDs
collimator
continuous scintillator CsI(Tl)
monolithic array of photodetectors
photodetector counts
Main advantages (vs. pixellated detectors, e.g. CdTe or CZT):
• spatial resolution (<mm) achieved with ~ 10 times larger photodetector pixel size
1/100 readout channels needed for a given spatial resolution
• good detection efficiency, adjustable vs. energy with scintillator thickness
Main disadvantage
Poorer energy resolution, especially at low energy, due to the scintillator conversion
(although new scintillators like LaBr3 are reducing this gap) and to the electronics noise
added by the several photodetectors used for the light readout
The HICAM gamma camera
The consortium:
• Politecnico di Milano, Italy
• MPI Halbleiterlabor, Germany
• L’ACN, Italy
• Nuclear Fields Holland
• UCL London, UK
• OORR-Bg, Italy
• Hospital San Pau, Barcelona, Spain
• University of Milan, Italy
• Cf Consulting, Italy
features:
• 10x10cm2 FOV
• intrinsic resolution ~ 1mm
• overall resolution ~ 2.5mm @5cm
• energy resolution ~ 10% @140keV
• compactness
• compatibility with MRI
Applications:
• planar clinical studies of spine and small
bones
• intra-operative imaging of breast cancer
and melanoma
• imaging of parathyroid and thyroid
• SPECT measures in test phantoms
• combined HI-CAM and MRI measures
• small animal imaging
(EC contract n. LSHC-CT-2006-037737)
10mm
10mm
1mm insensitive
bonding pads
bus lines
JFET
The SDD photodetector
• 1×5cm2 array
• ~ 20% dead area
• drift time <1us
• ARC transmittance
of 85% at 550nm (CsI(Tl))
scintillation entering side
drift
100cm225cm2
The detection module
The first camera prototype
• five 1×5cm2 modules
• T = -10°C
• flex cables to FE readout
• 1 readout ASIC (25ch)
for the whole camera
CsI(Tl) scintillator, 7mm thick
Roberta Peloso
Politecnico di Milano & INFN
Roberta Peloso
Politecnico di Milano & INFNNSS-MIC 2010, Knoxville, 2 Nov. 2010
~ 20% dead area
Assembly of 20 modules (100cm2 total) in the camera
120 mm
96 mm
Flat cables
to the FE electronics
detector modules
Peltier elements
heat dissipator
Roberta Peloso
Politecnico di Milano & INFN
Roberta Peloso
Politecnico di Milano & INFNNSS-MIC 2010, Knoxville, 2 Nov. 2010
Biasing and readout electronics of the camera
25-channels readout circuit
0.35mm CMOS technology
flex from
detector module
25-channels
readout boards
(x4)
board including biasing
and interface with DAQ
(SPI programming and
data acquisition)
Roberta Peloso
Politecnico di Milano & INFN
Roberta Peloso
Politecnico di Milano & INFNNSS-MIC 2010, Knoxville, 2 Nov. 2010
Data Acquisition System
ADCs
LVD
S in
terfa
ce
ASICs managementFrame event generation
Ethernet frame serviceEthernet control service
Ethernet clientSimple user interfaceProcessing software
PC
Roberta Peloso
Politecnico di Milano & INFN
Roberta Peloso
Politecnico di Milano & INFNNSS-MIC 2010, Knoxville, 2 Nov. 2010
Gamma-ray qualification of the camera: flood irradiation
one unit was no moreoperative during tests
Source: 99Tc (140keV)
A uniform flood is used to derive theuniformity correction map
CsI:Tl10mm
Gamma-ray imaging: first results
99Tc source (140keV)
lead collimator
HICAM detector
Hole Ø=1mm
Pitch=3mm99Tc source placed at 90 cm
Roberta Peloso
Politecnico di Milano & INFN
Roberta Peloso
Politecnico di Milano & INFNNSS-MIC 2010, Knoxville, 2 Nov. 2010
Irradiation with 99Tc through a grid (1)
Reconstruction ofthe gridby means ofcentroid algorithm
Roberta Peloso
Politecnico di Milano & INFN
Roberta Peloso
Politecnico di Milano & INFN
Roberta Peloso
Politecnico di Milano & INFNNSS-MIC 2010, Knoxville, 2 Nov. 2010
Mean FWHM =1.91mm
Mean FWHM =2.01mm
10,8 cm
8,7 cm
Irradiation with 99Tc through a grid (2)
X
Y
Roberta Peloso
Politecnico di Milano & INFN
Roberta Peloso
Politecnico di Milano & INFNNSS-MIC 2010, Knoxville, 2 Nov. 2010
Assembly of the camera head
Roberta Peloso
Politecnico di Milano & INFN
Roberta Peloso
Politecnico di Milano & INFNNSS-MIC 2010, Knoxville, 2 Nov. 2010