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Performances of a Performances of a pixel ionization pixel ionization
chamber to monitor chamber to monitor a voxel scan hadron a voxel scan hadron
beambeam
A.Boriano A.Boriano 33, F.Bourhaleb , F.Bourhaleb 2,32,3, R. Cirio, R. Cirio 3 3, M. Donetti , M. Donetti 2,32,3, ,
F. Marchetto F. Marchetto 33, C. Peroni , C. Peroni 33, C.J. Sanz Freire , C.J. Sanz Freire 1,31,3
11 Ion Beam Applications, Louvain la-Neuve, Belgium Ion Beam Applications, Louvain la-Neuve, Belgium22 TERA Foundation, Novara, Italy TERA Foundation, Novara, Italy
33 University and INFN, Torino, Italy University and INFN, Torino, Italy
PTCOG 2002 - Catania
outlineoutline
Mechanical structure of the pixel Mechanical structure of the pixel ionisation chamberionisation chamber
Read-out: electronics and performancesRead-out: electronics and performancesData Acquisition SystemData Acquisition SystemResults from test with protons at PSIResults from test with protons at PSIResults from test with CResults from test with C+6+6 at GSI (2000) at GSI (2000)
Preliminary results from test with CPreliminary results from test with C+6+6 at GSI (2002)at GSI (2002)
PTCOG 2002 - Catania
The pixel The pixel chamberchamber
parallel plate ionization chamber
anode segmented in 1024 square pixels
pixel dimension = 7.5 X 7.5 mm2
sensitive area = 24 X 24 cm2
1 mm water equivalent thickness
front-end electronics, located around the chamber, to perform analog to digital conversion
PTCOG 2002 - Catania
Detector Detector designdesign
The detector has to be thin to minimize the effects on the beam energy and shapeAnode and cathode are glued to frames in order to assure the mechanical rigidity and the gap thicknessWater equivalent thickness < 1 mm
PTCOG 2002 - Catania
Front-end Front-end electronicselectronics
located around the chamber
we have developed a full custom chip (TERA05)
every chip has 64 channels that convert the collected charge into counts
PTCOG 2002 - Catania
Linearity at 100 fC charge Linearity at 100 fC charge quantumquantum
20 pA < I < 0.6 A
Linearity better than 0.7 %
PTCOG 2002 - Catania
Linearity at 600 fC Linearity at 600 fC charge quantumcharge quantum
10 pA < I < 2 A
Linearity better than 0.3 %
PTCOG 2002 - Catania
Reproducibility of Reproducibility of charge quantumcharge quantum
I = 49.96 nAQc = 600 fC24 ºC < T < 27 ºC1 month6 measures
PTCOG 2002 - Catania
Data Data acquisitionacquisition
Signals (RS422 standard) are delivered via twisted pair flat cables (100 m maximum length)
max transfer rate = 10 MHz = 40 Mbyte/s
read out transfer time = 50 s
read out cycle total time = 100 s
real time operating system
<100 m
PTCOG 2002 - Catania
Beam test at PSIBeam test at PSI
PSI test with a 138 MeV proton PSI test with a 138 MeV proton beambeam
7 mm FWHM beam7 mm FWHM beam Spot-scanningSpot-scanning
Uniformity of the Uniformity of the response response ~0.9%~0.9%
Profiles measurement okProfiles measurement ok
PTCOG 2002 - Catania
Beam test at Beam test at GSIGSI
Beam characteristics
raster-scan delivery system
C+6, beam dimension = 8.8 mm (FWHM)
data acquisition synchronized with raster-scan
Aims
spatial resolution
homogeneity of response
PTCOG 2002 - Catania
Spatial resolutionSpatial resolution
Spatial resolution < 0.2 mm
PTCOG 2002 - Catania
Homogeneity of the Homogeneity of the responseresponse
18 × 18 cm2 uniform field18 × 18 cm2 uniform field
= 1.1 % = 1.1 %
= 2.0 % = 2.0 %
PTCOG 2002 - Catania
PMC
FIFO
CPU
Pixel chamber
PC
OUT16 bit
Operative Systen VxWorks with Tornado II environment
1024 pixel
4chip
4 chip
4 chip
4 chip
DAQ- test gsi 2002DAQ- test gsi 2002
PTCOG 2002 - Catania
49 pixels map
The map follows the beam...
Daq with 49 pixels mapDaq with 49 pixels map
PTCOG 2002 - Catania
Beam intensity Beam intensity dependencedependence
1 single voxel treated with several beam intensities Deviation from linearity is within 1%
PTCOG 2002 - Catania
Spatial resolutionSpatial resolution
14x14 cm2 field ~2100 voxels DAQ: 7x7 map that follows the beam
Spatial resolution < 0.2 mm
PTCOG 2002 - Catania
Detector Detector designdesignThick version
When used in plastic phantom the detector can be thick.With photon or electron beam air gap has to be minimized.Anode and cathode are glued to a plastic slab, which is a grid of 1024 holes.Each hole can be considered as an independent sensitive volume.
PTCOG 2002 - Catania
TERATERA0505Very Large Scale
Integration (VLSI)if conversionoutput Qint
100 fC<charge quantum<800 fCImax= 4 A64 channels16 bit wide countersmultiplexed digital outputdead-time free readoutmax read out rate = 10 MHz
channel # 1
channel # 64
PTCOG 2002 - Catania
Read out electronicsRead out electronicsRecycling Integrator architecture.
PTCOG 2002 - Catania
Spread of charge Spread of charge quantaquanta
RMS 1 %RMS 1 %
I = 49.96 nA
26 chips
PTCOG 2002 - Catania
Data acquisitionData acquisition
• connection by twisted pair flat cables (100 m max)
• max rate transfer = 1 MHz =
2 Mbyte/s
• read out transfer time = 1 ms
• PCI DAQ card
• LabVIEW software
• cheap solution
• easy to handle
Slow data acquisition
