Strip Chambers

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Strip Chambers

Outlook General Principle of RadiationTherapy Hadrontherapy CNAO Monitor System Test and Characterization Conclusions


General principle of radiationtherapy10080Tumourcontrolpr obabilit y [%]60402000 20 40 60 80 100 120dose [Gy]


General principle of radiationtherapypr obabilit y [%]100806040TumourcontrolComplicationrate2000 20 40 60 80 100 120dose [Gy]


HadrontherapyHadrons' beam for cancer treatment Low dose on surfaceDose [%]110100908070605040302010Carbon ionsElectrons High dose in depth High precision on dosedelivery Minimal lateral scatteringPhotons00 50 100 150 200 250 300Dept h [mm]


The Centro Nazionale di AdroterapiaOncologicaCNAO - PaviaWORK IN PROGRESS!!!!!


The CNAO synchrotronProtons : 60 – 250 MeVCarbon Ions : 120 – 400 MeV/uActive System of dosedistributionBeam dimension :4-10 mm (FWHM)Field dimension :20 x 20 cm 23 treatment rooms :3 horizontal lines1 vertical line


Active System of dose distributionLinacProtonsourceCarbonsourcedE/dzSynchrotronZEcScanningmagnetsMonitorsystemINFN and University of TorinoCollaborate with Fondazione CNAO


BOX 1 BOX 2Integral Chamber:Intensity MeasurementDetection SystemStrip Chambers:Position MeasurementIntensity MeasurementPrecision 100 µmIntegralChamber:IntensityMeasurementPixel Chamber:2D PositionMeasurement2D IntensityMeasurementPrecision 200 µmIntegral 1STRIP XSTRIP YIntegral 2PIXEL


Detectors Characteristicsstrippixel5mm gap between cathode andanodeAnode segmented in 128 strip1,55 mm wide with 0,1 mm ofspace5mm gap between cathode andanodeSegmented anode in 1024 pixelpitch : 6,6 mm


Detector assembly


Detector Assembly BOX1Cleaning of the box thatcontains the detectorVerification of the gas setupExternal FoilStrip Y AnodeKapton FrameCathode Strip chambersStrip X AnodeIntegral AnodeCathode Integral chamberxzyBeamyxC5C4 D2 C3S2D1C2S1 C1zBeamBaseBOX 1


Detector Assembly BOX1Cleaning of the box thatcontains the detectorVerification of the gas setupExternal FoilStrip Y AnodeKapton FrameCathode Strip chambersStrip X AnodeIntegral AnodeCathode Integral chamberxzyBeamC5C4 D2 C3S2D1C2S1 C1BeamCoverBOX 1


Detector Assembly BOX1Cleaning of the box thatcontains the detectorVerification of the gas setupExternal FoilStrip Y AnodeKapton FrameCathode Strip chambersStrip X AnodeIntegral AnodeCathode Integral chamberxzyBeamyxC5C4 D2 C3S2D1C2S1 C1zBeamCoverBOX 1


Detector Assembly BOX1Cleaning of the box thatcontains the detectorVerification of the gas setupExternal FoilStrip Y AnodeKapton FrameCathode Strip chamberStrip X AnodeIntegral AnodeCathode Integral chamberxzyBeamyxC5C4 D2 C3S2D1C2S1 C1zBeamCoverBOX 1


Detector Assembly BOX1Cleaning of the box thatcontains the detectorVerification of the gas setupExternal FoilStrip Y AnodeKapton FrameCathode Strip chamberStrip X AnodeIntegral AnodeCathode Integral chamberxzyBeamyxC5C4 D2 C3S2D1C2S1 C1zBeamCoverBOX 1


Detector Assembly BOX1Cleaning of the box thatcontains the detectorVerification of the gas setupExternal FoilStrip Y AnodeKapton FrameCathode Strip chamberStrip X AnodeIntegral AnodeCathode Integral chamberxzyBeamyxC5C4 D2 C3S2D1C2S1 C1zBeamCoverBOX 1


Detector Assembly BOX1Cleaning of the box thatcontains the detectorVerification of the gas setupExternal FoilStrip Y AnodeKapton FrameCathode Strip chambersStrip X AnodeIntegral AnodeCathode Integral chamberxzyBeamyxC5C4 D2 C3S2D1C2S1 C1zBeamCoverBOX 1


Detector Assembly BOX1Cleaning of the box thatcontains the detectorVerification of the gas setupExternal FoilStrip Y AnodeKapton FrameCathode Strip chambersStrip X AnodeIntegral AnodeCathode Integral chamberxzyBeamyxC5C4 D2 C3S2D1C2S1 C1zBeamCoverBOX 1


Detector Assembly BOX1Cleaning of the box thatcontains the detectorVerification of the gas setupExternal FoilStrip Y AnodeKapton FrameCathode Strip chambersStrip X AnodeIntegral AnodeCathode Integral chamberGap FramexzyBeamyxC5C4 D2 C3S2D1C2S1 C1zBeamCoverBOX 1


Detector Assembly BOX1Cleaning of the box thatcontains the detectorVerification of the gas setupExternal FoilStrip Y AnodeKapton FrameCathode Strip chambersStrip X AnodeIntegral AnodeCathode Integral chamberGap Frame 5mmxzyBeamyxC5C4 D2 C3S2D1C2S1 C1zBeamCoverBOX 1


Detector Assembly BOX1Cleaning of the box thatcontains the detectorVerification of the gas setupExternal FoilStrip Y AnodeKapton FrameStrip chambersStrip X AnodeIntegral AnodeCathode Integral chamberGap Frame 5mmxzyBeamyxC5C4 D2 C3S2D1C2S1 C1zBeamCoverBOX 1


Detector Assembly BOX1Cleaning of the box thatcontains the detectorVerification of the gas setupExternal FoilStrip Y AnodeKapton FrameCathode Strip chambersStrip X AnodeIntegral AnodeCathode Integral chamberGap Frame 5mmxzyBeamyxC5C4 D2 C3S2D1C2S1 C1zBeamCoverBOX 1


Detector AssemblyBox 1 Box 2


Readout ElectronicsFRONT END TERA 06Strip and Pixel chambers readout•Recycling integrator architecture•64 channels•100 fC ≤ charge quantum ≤ 800 fC•Max counting rate 5 MHz•Acquisition speed 10 MHz•Latch dead time free read-out•Non Linearity


Characterization of theFRONT END TERA06Verification of the differentfunctionalities of the boards•Pedestal (Background Currents)•Charge Quantum


PedestalsThe mean value reportedfor the pedestal of all 40 electronicsboards is 0.62with a percent relative error of 10%Pedest al Mean ValuesMean Values (count s/ s)10,950,90,850,80,750,70,650,60,550,5009_00815_4617_1021_2430_3134_2640_3842_4155_3261_5665_6266_5471_6872_5779_6981_7882_8386_8487_7597_8598_3799_90104_89107_115108_106111_109115_107120_119122_118123_100125_124126_128127_92130_117131_33132_105133_60134_129135_58136_76138_137Fr ont End Ter a 06


ChargeQuantumAll the electronics boards tested areclosely to a mean value of 210 fC and arelative error of 1.8%Charge Quant um Mean Values220215210205200195108_106115_10766_5446_15123_100122_11842_41138_13734_2631_3097_8555_32135_58132_10521_24131_3398_37136_7681_7861_56120_11979_6999_90130_11786_8483_829_8133_60134_12987_75125_12471_68111_10940_38128_126127_92104_08965_6272_5717_10Char ge Quant um (f C)Fr ont End Ter a 06


Detectors characterization Preliminar X Rays testsPreliminar X Rays testsVerification of the correct workingof the detectorsSelection of the first couple ofdetectors for deepercharacterization tests


Experimental SetupPXI CRATE NIfor DAQX Ray sourcewith2mm diametercollimatorBOX containingthe ionizationchambersX Ray Source (IMD,Model BASIC 4006)50 KV, 160 mAs


The chambers have the same gap andare under the same conditions (HV, gasflux, etc), but there are big differencesbetween the signals collected by eachone of themStpX/Integral 1 1.42StpY/Integral 1 0.93Pixel/Integral 2 6.40Radiation interaction withmatter for photons at lowenergies!!!!!


yBOX 1MaterialThickness(mm)xzC5Beam123AluminiumMylarNitrogen12,00 E-35,00C5C445678MylarAluminiumNitrogenAluminiumKapton12,00 E-35,0017,00 E-325,00 E-3C4INT 1C3C3Integral chamber910111213NitrogenKaptonAluminiumNitrogenAluminium5,0025,00 E-317,00 E-35,00S2STP XS2C2Strip X chamber14 Mylar 25,00 E-3C215AluminiumStrip Y chamber161718NitrogenAluminiumKapton5,0017,00 E-325,00 E-3STP YS1S11920NitrogenMylar5,0012,00 E-3C1C1


yBOX 2xBeam12MaterialAluminiumMylarThickness (mm)12,00 E-3C1C1345678NitrogenMylarAluminiumNitrogenAluminiumKapton5,0012,00 E-35,0017,00 E-325,00 E-3C2INT 2C3C2C3Integral chamber9Nitrogen5,001011121314KaptonCooperNitrogenAluminiumMylar50,00 E-320,00 E-35,0012,00 E-3PXCPXC ChamberC4PXCC4Pixel chamber15Nitrogen5,001617MylarAluminium12,00 E-3C5C5


The signalγγDepending on the Z of theCathode/anode materialand the thicknessof it, the external contributioncan change significantlyMyAlThe signal produced andcollected in the detector willhave two main contributions:S TOT = S I+ S EWhere:S I: Internal contributionSignal produced by the γinteraction with the N 2e - e -∆VS ES IS E:External contributionSignal produced by the γinteraction with the material ofthe cathode or anodeAlKapton


Simulation X Ray Probabilitydistribution spectrum XOP 2.1 Input parameters:• Voltage 50kV• Al filter 5mm Photon’s interaction with matter Electron Gamma Shower (EGS)• DOS XYZ• Cut off energy for the electrons: 1keV• Physics for low energiesProbability0.30.250.20.150.10.0500.015 0.02 0.025 0.03 0.035 0.04 0.045 0.05Energy (M eV)


ResultsBOXRatioExperimentalSimulatedSTPX/INT11,421,401STPY/INT10,931,00STPX/STPY1,541,402PXC/INT26,405,60


Characterization of thefirst couple of detectorsBOX 1-2 “C” Background Currents Reproducibility on a single point Uniformity of the sensitive area


PedestalsCount s/ s1.110.90.80.70.6Mean Counts/s at400V for the Stripand PixelChambers0.5Average of0.40 10 20 30 40 50 60 70 80 90 100 110 1200.85 counts/sChannelSTP X STP Y1.4Mean Count s/ s1.210.80.6Average of0.94 counts/s0.40 200 400 600 800 1000Number of channel


Background CurrentsPixel and Strip ChambersMean Background current(f A) per channel190180170160150Pixel chamber 157 fAStrip Y chamber 178 fAStrip X chamber 167 fA100 200 300 400 500 600Volt age (V)St r ip X St r ip Y PixelCharge Quantum 200 fCFor each voltage the measurement was repeated five times, every 60s


Background CurrentsIntegral ChambersMean Backgr ound cur rentper channel (f A)100 200 300 400 500 6000-100-200-300-400-500Voltage (V)Integral 150fC -371 fA200fC -208 fA350fC -218 fA50 f C 200 f C 350 f CIntegral 250fC 1302 fA200fC 189.5 fA350fC 119 fAMean Backgr ound Cur r entper channel (f A)25002000150010005000100 200 300 400 500 600Volt age (V)50 f C 200 f C 350 f C


Reproducibility on asingle point 4 series of data (in different points of thesensitive area)10 runs for each seriesOnly a 5x5 pixel area and 20 strips are takinginto account to analyze the data (pixels/stripsthat were hit by the beam)


ReproducibilityRatios between the chambersin order to avoid the uncertaintiesSt r ip X/ I nt egr al 1of the X Ray SourceRat io1,31,291,281,271,261,251,241,231,221,211,21,190 2 4 6 8 10RunStpX/Integral 1 0.42%StpY/Integral 1 0.66%Pixel/Integral 2 1.75%Ser ie 1 Ser ie 2 Ser ie 3 Ser ie 4St r ip Y/ I nt egr al 1Pixel/ I nt egr al 2Rat io0.890.880.870.860.850.840 2 4 6 8 10RunRat io (Pxc/ I nt 2)1.941.921.91.881.861.841.821.81.781.761.741.721.71.680 2 4 6 8 10RunSer ie 1 Ser ie 2 Ser ie 3 Ser ie 4Ser ie 1 Ser ie 2 Ser ie 3 Ser ie 4


Gain UniformityMoving BOX Scan on 64 points8x8 matrixMoving thehead of the XRay Source


Gain UniformityMeasuredTotal systematic error on the surfaceof the chamber as a function of theposition of the beam on thechamber’s sensitive area( ) ( ) ( ) σ = σ2+ σ2total2 statf gainStatistical error onone point of thechamber“Statisticalfluctuation”MeasuredGain error of thechamber


Gain UniformityRMSStripXStripYIntegral1Integral2Pixel%σ total1.841.862.172.521.73%σ statf0.720.720.771.680.36%σ gain1.691.712.031.891.70


ConclusionsBox 1 Box 2Bkgnd currents 3 orders of magnitudesmaller than thetypical therapy one(~10nA)Reproducibility 0.42% StpX/Int1 0.66% StpY/Int1Uniformity: 1.70% for the stripchambers 2.03% for the integralchamberBkgnd currents: PXC: 157 fA INT2:• Bkg current toolarge at 50fC• Repeated trend:dependence ofBkg current withHigh VoltageReproducibility PXC/INT2: 1.75%Uniformity INT2: 1.89% PXC: 1.70%


Future Perspectives Characterization of couples “A”, “B”, “D” and “E” Improvement of the functionalities for BOX 2 “C” Bkg current dependence with HV Reproducibility Further characterization tests at a clinical LINAC Commissioning of the first beam line at CNAO


Thank youEspecially to theTERA Torino group!

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