, T. Gys, C. Joram, M. Moll and L. RopelewskiCERN - PDF document

C. D’Ambrosio , T. Gys, C. Joram, M. Moll and L. RopelewskiCERN –PH/DT2 3a Scintillators CERN Academic Training Programme2004/2005 Particle Detectors –Principles and Techniques scintillator (crystalline structure)Up to 40000 photons per MeVLarge variety of Z and Undopedand doped s decay timesE.m. calorimetry (e, MedicalimagingFairlyRad. Hard (100 kGy/year)(plastics or liquid solutions)Up to 10000 photons per MeVTracking, TOF, trigger, veto counters, sampling calorimeters. C. D’Ambrosio , T. Gys, C. Joram, M. Moll and L. RopelewskiCERN –PH/DT2 3a Scintillators CERN Academic Training Programme2004/2005 Particle Detectors –Principles and Techniques •fast recombination (ns-•delayed recombination due to •full control of growth, doping and conduction bandvalence band Eg C. D’Ambrosio , T. Gys, C. Joram, M. Moll and L. RopelewskiCERN –PH/DT2 3a Scintillators CERN Academic Training Programme2004/2005 Particle Detectors –Principles and Techniques BGO PbWO Temperature [ÞC]Photocurrent [nA]012345Dose [Gy] crystal nr 1266dose rate ~150 mGy/h (From Bicroncatalogue)crystal is used in CMS ECAL and its ~2% light Casks for Low dose irradiation of an oldcrystal and check of the temperature dependence of e blue curve is the photocurrent generated by the irradiation and the red curve is the temp C. D’Ambrosio , T. Gys, C. Joram, M. Moll and L. RopelewskiCERN –PH/DT2 3a Scintillators CERN Academic Training Programme2004/2005 Particle Detectors –Principles and Techniques TheintensityI ofa gamma beamtraversinga targetofthicknessd isWhereµisthesumofthreeprocessestakingplace in thematerial:toE(curvewillextendto higherenergies, seeChristian’s talk) Photon absorption in crystalsdeII0 C. D’Ambrosio , T. Gys, C. Joram, M. Moll and L. RopelewskiCERN –PH/DT2 3a Scintillators CERN Academic Training Programme2004/2005 Particle Detectors –Principles and Techniques GSOPbWO Decay timeof max.Em.Densitycomposition Hygroscopic; 3) Water soluble C. D’Ambrosio , T. Gys, C. Joram, M. Moll and L. RopelewskiCERN –PH/DT2 3a Scintillators CERN Academic Training Programme2004/2005 Particle Detectors –Principles and Techniques 152 Eu050100150200250300350400Countsx 0.1344 keV163 keV (122 + Sm K)122 keV (2 x Sm K)41 keV(Sm K line)escape each detected gamma provides an amplitude signal, atomic or nuclear spectra, new crystals, detectors, special probes, etc.. Energy[keV] 152 Eu30000400005000060000 ounts344 keV122 keV 82 keV(2 x Sm K)41 keV(Sm K line)X-rayandgamma spectroscopyYAP(Ce) crystal by Radio. source C. D’Ambrosio , T. Gys, C. Joram, M. Moll and L. RopelewskiCERN –PH/DT2 3a Scintillators CERN Academic Training Programme2004/2005 Particle Detectors –Principles and Techniques http://www.medical.philips.com/main/products/pet/products/gemini/clinicalimages C. D’Ambrosio , T. Gys, C. Joram, M. Moll and L. RopelewskiCERN –PH/DT2 3a Scintillators CERN Academic Training Programme2004/2005 Particle Detectors –Principles and Techniques •Basic scintillation mechanisms in organic scintillators•Försterenergy transfer and self absorption •One dopantand two dopantsscintillators•Readout of scintillators•Applications of organic scintillators•Example: small diameter scintillating fibresand their readout C. D’Ambrosio , T. Gys, C. Joram, M. Moll and L. RopelewskiCERN –PH/DT2 3a Scintillators CERN Academic Training Programme2004/2005 Particle Detectors –Principles and Techniques increaseswithdoping concentration, thatissmallerlight yieldsandshorterattenuationlengths:Therefore, adda lowconcentration wavelenghtshifter(2 dop. Scheme)Findlarge Stokes shift dopants The FörstertransferEfficient Förstertransfer asks for where the integral is the overlap between Acceptor abs. and dfRkADDADAD46)()(1 PVT (polyvinyl toluene) C. D’Ambrosio , T. Gys, C. Joram, M. Moll and L. RopelewskiCERN –PH/DT2 3a Scintillators CERN Academic Training Programme2004/2005 Particle Detectors –Principles and Techniques scintillators, down to ~1mm fibres.Förstertransfer) as it is the case for small diameter fibres Application ofthetwotypes ofdoping UV laser light 1 dop. Scheme (PS+PMP)2 dop. Scheme (PS+p-Ter+POPOP) Plastic microfibresbundle (30 µm dia.) ~1 mm C. D’Ambrosio , T. Gys, C. Joram, M. Moll and L. RopelewskiCERN –PH/DT2 3a Scintillators CERN Academic Training Programme2004/2005 Particle Detectors –Principles and Techniques Readout has to be adapted to geometry, gra•Light guides: transfer by total internal reflection (+outer reflector) •wavelength shifter (WLS) bars Photo detectorprimary particle UV (primary)blue (secondary)greensmall air gapscintillatorWLS “fish tail”adiabatic C. D’Ambrosio , T. Gys, C. Joram, M. Moll and L. RopelewskiCERN –PH/DT2 3a Scintillators CERN Academic Training Programme2004/2005 Particle Detectors –Principles and Techniques Large volume liquid or solid detectors (in foin CMS or , etc.), counters, light guides.High precision, small volume active targets and fibretracking (UA2, D0, CHORUS). Most commonapplications oforganicscintillators corepolystyrenen=1.59cladding(PMMA)n=1.49 typically 1 mm typ. 25 %3)cos1(5.042 d n1n2 3.5)cos1(5.042 d mouter claddingn=1.42 m Double cladding system (developed by RD7) C. D’Ambrosio , T. Gys, C. Joram, M. Moll and L. RopelewskiCERN –PH/DT2 3a Scintillators CERN Academic Training Programme2004/2005 Particle Detectors –Principles and Techniques Small diameter scintillating fibresreadoutThe readout of fibresis a key point for the whole systemActive target in WA84 (1989)high granularity of the fibresand bunch crossing time, but stay in the ex: a real challenge.was especially developed for this ( C. D’Ambrosio , T. Gys, C. Joram, M. Moll and L. RopelewskiCERN –PH/DT2 3a Scintillators CERN Academic Training Programme2004/2005 Particle Detectors –Principles and Techniques •New dopants•High granularity •Larger attenuation lengths•New