1、Improvement in scintillation counter energy resolution with the silicon drift detector*Shuji Maeo1,2, Takayuki Yanagida1, Yuui Yokota1 and Akira Yoshikawa1,31Division of Physical Process Design,Institute of Multidisciplinary Research for Advanced Materials (IMRAM),Tohoku University2Japan Association
2、 for the Advancement of Medical Equipment3New Industry Creation Hatchery Center(NICHe), Tohoku UniversityIntroductionl High energy radiation measurementsl Scintillation counter is useful.RadiationScintillator Light detectorTo processorTypical detector is Photo Multiplier Tube(PMT).ProblemsEnergy res
3、olution is not enough.It can not use in magnetic fields.Going to semiconductorLight Electrical signal In Conventional photo diode(PD), signal intensity is low, noise level is high(low S/N ratio). In Avalanche PD(APD), S/N ratio is not so high.Scope of researchl Improvement of S/N ratio in Scintillat
4、ion counterl Using an Silicon drift detector (SDD) as light detectorlEstimations using the SDDlProblems and Next planHigh energy resolutionApplying PD array etc.High contrast imagingIn this reportComparison with each light detectorPMT Si-pin PD APD SDDStructure Electron from Photocathode is amplifie
5、d by dynode.Semiconductor witn pn junction.Similar to pin PD. Electron is amplified by avalanche effect for high reverse bias.Small anode at center of the detector can collect charge efficiently by electric field. Count rate 107 cps 104 cps 106 cps 106 cpsEnergy resolution Characteristic - High volt
6、age operation.- Susceptible by ambient electric field and magnetic field.- Cheapness.- Easy operation.- Large signal- High voltage operation.- Large leakage current.- Expensive.- High energy resolution.Characteristics of the SDDl Electron can be collected efficiently for electric field formed by rin
7、g like cathode.l Anode capacitance is low for small anode size.l Field Effect Transistor(FET) can be constructed at SDD directly.l Thermal noise can be reduced for cooling by the peltier cooler.l High energy resolution and high count rate are available.Structure of the SDDP. Lechner et al., Nucl. In
8、strum. Methods, vol. A-377, 346 (1996).Affects of energy resolutionSimulation results of peak shape depended on each resolution.Comparison of X-ray responseFWHM： 1.7 keV(2.9%)Np-L13.9 keVNp-L17.7 keVNp-L20.8 keV26.4 keV59.5 keVSpectrum of 241Am measured by conventional Si-pin PDSpectrum of 241Am mea
9、sured by the SDDNp-L13.9 keVNp-L17.7 keVNp-L20.8 keV26.4 keV59.5 keVFWHM： 0.8 keV(1.3%)Hamamatsu (S1722-02) KETEKLinearity of the pulse heightfor X-raysCalibration curveNp-L13.9 keVNp-L17.7 keVNp-L20.8 keV26.4 keV59.5 keVIt can be estimated that linearity between pulse height and energy.Linearity of
10、 the pulse heightfor visible lightRed LED voltage / mV100 200 300 400 500 600 700 Out put signal distribution ofLED light (red) applied each biasRelation between pulse heightand LED biasIt can be estimated that linearity between pulse height and luminosity.Advantage of using the SDDHigh energy resolutionHigh energy radiation spectrometryImagingQualitative analysisAccuratelyQuantitative analysisSensitiveImageHigh ContrastMeas. timebecome Short
