Silicon strip detectors for two-dimensional
soft x-ray imaging at normal incidence
Pedro Rato Mendes
LIP Lisbon and University of Algarve, Portugal
Amsterdam, 09-12 September 2002
Outline
• Collaboration members
• Objectives
• Experimental setup
• Energy calibration
• Imaging results
• Conclusions and future work
Pedro Rato Mendes et al.
IWoRID’2002 - Amsterdam
Collaboration members
M. C. Abreu a, G. Baldazzi b, D. Bollini b, E. Cabal Rodriguez c,
W. Dabrowski d, A. Diaz Garcia c, M. Gambaccini e, P. Giubellino f,
M. Gombia b, P. Grybos d, M. Idzik d,f, A. Marzari-Chiesa g, L. M. Montano h,
F. Prino i, L. Ramello i, P. Rato Mendes a, S. Rodrigues a, M. Sitta i, P. Sousa a,
K. Swientek d, A. Taibi e, A. Tuffanelli e, R. Wheadon f, P. Wiacek d
a
b
LIP and University of Algarve, Faro, Portugal
Dipartimento di Fisica dell’Università di Bologna and INFN, Bologna, Italy
c
d
CEADEN, Havana, Cuba
Faculty of Physics and Nuclear Techniques, Academy of Mining and Metallurgy, Cracow, Poland
e
Dipartimento di Fisica dell’Università di Ferrara and INFN, Ferrara, Italy
f
g
Dipartimento di Fisica Sperimentale dell’Università di Torino and INFN, Torino, Italy
h
i
INFN , Torino, Italy
CINVESTAV, Mexico City, Mexico
Dipartimento di Scienze e Tecnologie Avanzate dell’Università del Piemonte Orientale and INFN ,
Alessandria, Italy
Pedro Rato Mendes et al.
IWoRID’2002 - Amsterdam
Objectives
Develop a simple prototype system for 2-D
soft x-ray imaging using silicon strip detectors
• Motivations for this prototype
– spin-off from high-energy physics
– RX64 chip designed for this application
– simple laboratory setup and data-acquisition
– advanced education for young physicists
RX64 and its main applications: talk by L. Ramello, this conference
W. Dabrowski et al., RX64 – A Fully Integrated 64-channel IC for Readout of Silicon Detectors
Used for X-Ray Position Sensitive Measurements, IEEE NSS/MIC 2001, San Diego
Pedro Rato Mendes et al.
IWoRID’2002 - Amsterdam
Experimental setup
• Equipment
– board with 1-sided microstrip detectors and RX64 chips
• 300 m thick Si, 132 strips at 100 m pitch (ITC-IRST, Trento, Italy)
• RX64 chip by W. Dabrowski and collaborators (Cracow, Poland)
• one or two chips per board (64 or 128 channels)
–
–
–
–
PC with NI PCI-DIO-96 interface + LabVIEW 6i software
scanning system controlled by stepper motor
radiation sources (57Co, 109Cd, 241Am for fluorescence)
power supplies, cables
• Two-dimensional image acquisition
– acquire 1-D profiles for each collimator position
– form 2-D image by juxtaposition of 1-D profiles
Pedro Rato Mendes et al.
IWoRID’2002 - Amsterdam
Experimental setup
silicon microstrip detector
PC
National
Instruments
64
PCI-DIO-96
LabVIEW 6i
RX64
- 64 channels (preamp, shaper, discriminator)
- 64 pseudo-random counters (20-bit)
- internal calibration circuit (1 mV to 30 mV)
- I/O on chip (interface with external bus)
Pedro Rato Mendes et al.
RX64
IWoRID’2002 - Amsterdam
First test board (one RX64 chip)
0.6  1.0 cm2
detector
RX64
Pedro Rato Mendes et al.
IWoRID’2002 - Amsterdam
Energy calibration
• Method
– perform discriminator threshold scan
– differentiate integral spectrum
– fit energy peaks on differential spectrum
integral spectrum
Pedro Rato Mendes et al.
differential spectrum
IWoRID’2002 - Amsterdam
Energy calibration
Calibration using Co57 and Cd109 sources
(board with one RX64 chip, average on all channels)
Pedro Rato Mendes et al.
IWoRID’2002 - Amsterdam
Energy calibration
Calibration using Am241 x-ray fluorescence source
(board with two RX64 chips, average on all channels)
Pedro Rato Mendes et al.
IWoRID’2002 - Amsterdam
Scanning system
stepper motor
scanning
radioactive source
Pb collimator
detector board
Pedro Rato Mendes et al.
IWoRID’2002 - Amsterdam
Imaging results – one RX64 chip
300 kBq 109Cd source – 22 keV Ag K x-rays
15 mm thick Pb collimator, 300 µm wide slit
Pb
0.5 mm
thick
scanning
system
microstrip
detector
1.0  1.0 mm2
Pedro Rato Mendes et al.
IWoRID’2002 - Amsterdam
Imaging results – two RX64 chips
300 kBq 109Cd source – 22 keV Ag K x-rays
15 mm thick Pb collimator, 300 µm wide slit
HIGH CONTRAST
8-pin integrated circuit
Pedro Rato Mendes et al.
1.0  1.0 mm2
LOW CONTRAST
snail shell
IWoRID’2002 - Amsterdam
Conclusions
We have built and tested a simple prototype
for 2-D soft x-ray imaging
• Prototype main features
– one-sided silicon microstrip detectors
– simple readout electronics based on RX64 chip
– simple 2-D scanning system
• Future developments
– larger area sensors / more readout chips
– new chip version with two thresholds
– x-ray tube as radiation source
Pedro Rato Mendes et al.
IWoRID’2002 - Amsterdam