Proton detection with the R3B calorimeter,
two layer solution
IEM-CSIC sept. 2006 report
MINISTERIO DE EDUCACINY CIENCIAO. Tengblad, M. Turrin Nieves, C. Pascual Izarra, A. Maira Vidal
Olof Tengblad R3B colaboration: Milano Oct 3-6 2006
outlineWhy a two layer solution
Limitations - requirements
Conclusion
Olof Tengblad R3B colaboration: Milano Oct 3-6 2006
Energy loss of charged particles: Bethe-Bloch equationenergy loss detectedincident energy (MeV)
Olof Tengblad R3B colaboration: Milano Oct 3-6 2006
Proposed scenarioTwo layers detector:Simplificationthe estimated final energy is proportional to the energy deposited in each layer E= f( D E1 ) + g( D E2 )
D E1D E2
Olof Tengblad R3B colaboration: Milano Oct 3-6 2006
SRIM Simulations: Deposited energy of protonsFit: Gaussian with a constant background
Olof Tengblad R3B colaboration: Milano Oct 3-6 2006
SRIM Simulations: protonsED E1D E2Material: LaBr3(:Ce)Thickness: 1mm+20mmMonte Carlo: SRIM 2003DE1+s(DE1) DE2+s(DE2)
Olof Tengblad R3B colaboration: Milano Oct 3-6 2006
Energy resolutionE DE1+D(sE1) DE2+s(DE2)sE?20050MeV(sE/E=25%)
20010MeV(sE/E=5%)protons of 200MeV deposit an energy of:1mm LaBr3= 1.490.23 MeV
20mm LaBr3= 31.321.13 MeV
Olof Tengblad R3B colaboration: Milano Oct 3-6 2006
First Conclusions
If not fully stopped, two DE-detectors are requiredA too thin detector gives bad estimation of the energy leading to bad resolution first detector should be thick in order to totally absorb protons up to rather high energySecond detector placed to solve the ambiguity on the signal
The gammas will deposit most of the energy aroundthe first hit, which we want to be the first detector, why this crystal should have a good Eg resolution.Two detectors of different materials with a unique PM or APD? Optically compatible
Olof Tengblad R3B colaboration: Milano Oct 3-6 2006
Detector spectral response matchingHautefeuille et al. J. of Crystal Growth (in press)Emission and absorption spectra do not overlap emitted light is not re-absorbedEmission spectra shifted to lower energiesLYSO:
lexcitation [nm] =262, 293, 357Max. lemission [nm] =398, 435
Olof Tengblad R3B colaboration: Milano Oct 3-6 2006
Emission spectra Max. lemission [nm] Decay time[ns] CsI(Tl)5501000BGO 478300CsI pure31516
LYSO (Ce)42045-60CsI(Na)420630NaI(Tl)400230
LaBr3 (Ce)38016LaCl3 (Ce)35028NaI(Tl)BGOCsI(Tl)LYSOLaBr3
Olof Tengblad R3B colaboration: Milano Oct 3-6 2006
ScintillatorsW.W. Moses NIMA 487 (2002) 123LYSO (Lu1.8Y0.2SiO5:Ce)Light output 25000 photons/MeVDecay time 45-60nsDensity 7.1 g/cm2LaBr3 (:Ce)Light output 61000 photons/MeVDecay time 16nsDensity 5.3 g/cm2
Olof Tengblad R3B colaboration: Milano Oct 3-6 2006
SRIM simulations: protonsMaterials: LYSO(:Ce) + LaBr3(:Ce) Thickness: 30mm + 20mm Monte Carlo: SRIM 2003ED E1D E2
Olof Tengblad R3B colaboration: Milano Oct 3-6 2006
Energy resolutionDE1+D(sE1) + DE2+s(DE2) E + sE? protons of 200MeV deposit an energy of:
30mm LYSO= 67.441.77 MeV
20mm LaBr3= 43.503.11MeV2007MeV(sE/E=3.5%)
20010MeV(sE/E=5%)
Olof Tengblad R3B colaboration: Milano Oct 3-6 2006
Gamma absorptionMinimum absorption for g ~5MeV55% of g absorbed in 30mm LYSO (Prelude)
Olof Tengblad R3B colaboration: Milano Oct 3-6 2006
Second ConclusionProtonsTwo detectors are required to detect 300 MeV protonsThe energy of the incident protons can be estimated with an error of ~3-4% with the LYSO + LaBr3(Ce) solutionGammasMost of the energy of the gammas is deposited around the first hit, why this should happen in the first layer!55% of g are absorbed in 30mm LYSO when the energy of the incident gammas is 5MeV>55% of g are absorbed for E5MeV in 30mm LYSOThe rest will be absorbed in the second layerIf first gamma detected in second layer; event discardedHowever, the gamma resolution in LYSO is about 6%If this g-resolution is good enough one would choose LSO + LYSO as the resolution of LaBr is too good to be place as second layer.
Olof Tengblad R3B colaboration: Milano Oct 3-6 2006
Final ConclusionTo obtain the optimum situation both for protons and gammas;First crystal layer relatively thick and of a material with excellent gamma resolution, LaBr3(Ce) of 30 mm l = 380nm decaytime= 16nsSecond crystal layer of a material emitting at shorter wavelength and with a decay constant different in order to separate the signals and that the second detector is transparent to the first. LaCl3(Ce) of 150 mm l = 350nm decaytime= 25ns
This will detect protons up to 280 MeV with an proton energy resolution of the order of 2%.
One could, however, live with a much shorter LaCl3(Ce) or one could combine the LaBr3(Ce) with pure CsI as a cheaper solution.
Olof Tengblad R3B colaboration: Milano Oct 3-6 2006
TestsTwo H8500 Flat panel Photomultiplier tube 8x8
MPET-H8500 readout interfaceTwo scintillator arrays: BrilLanCe 380 Full detection area 2x 2, 4x4x30 mm3, encapsulated in Al housing, 3mm glass window10x10 crystals PreLuDe 420 Full detection area 2x 2, 4x4x30 mm312x12 crystals
Olof Tengblad R3B colaboration: Milano Oct 3-6 2006
Prelude420(60mm) vs CsI(90mm)Protons:Deposit energyProtons:Range in materialGamma:Absorption vs energy
Olof Tengblad R3B colaboration: Milano Oct 3-6 2006
LaBr3(:Ce) different thicknessesProtons:Deposit energyProtons:Range in materialGamma:Absorption vs energy
Olof Tengblad R3B colaboration: Milano Oct 3-6 2006
30 mm crystalProtons:Deposit energyProtons:Range in materialGamma:Absorption vs energy
Olof Tengblad R3B colaboration: Milano Oct 3-6 2006
CsI 90 200 mmProtons:Deposit energyProtons:Range in materialGamma:Absorbtion vs energy
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