1 Proton detection with the R3B calorimeter, two layer solution IEM-CSIC sept report MINISTERIO DE EDUCACIÓN Y CIENCIA CONSEJO SUPERIOR DE INVESTIGACIONES CIENTÍFICAS O. Tengblad, M. Turrión Nieves, C. Pascual Izarra, A. Maira Vidal

Olof Tengblad R3B colaboration: Milano Oct outline  Why a two layer solution  Limitations - requirements  “Conclusion”

Olof Tengblad R3B colaboration: Milano Oct Energy loss of charged particles: Bethe-Bloch equation energy loss detected incident energy (MeV)

Olof Tengblad R3B colaboration: Milano Oct Proposed scenario  Two layers detector :  Simplification the estimated final energy is proportional to the energy deposited in each layer E Ë=  f(  E 1 ) + g(  E 2 )  E 1  E 2

Olof Tengblad R3B colaboration: Milano Oct SRIM Simulations: Deposited energy of protons Fit: Gaussian with a constant background

Olof Tengblad R3B colaboration: Milano Oct SRIM Simulations: protons E  E 1  E 2  Material: LaBr 3 (:Ce)  Thickness: 1mm+20mm  Monte Carlo: SRIM 2003         

Olof Tengblad R3B colaboration: Milano Oct Energy resolution E            200±50MeV (  E/E=25%)  200±10MeV (  E/E=5%) protons of 200MeV deposit an energy of: 1mm LaBr 3 = 1.49±0.23 MeV 20mm LaBr 3 = 31.32±1.13 MeV

Olof Tengblad R3B colaboration: Milano Oct First Conclusions If not fully stopped, two  E-detectors are required A 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 energy Second 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 E  resolution.  Two detectors of different materials with a unique PM or APD?  Optically compatible

Olof Tengblad R3B colaboration: Milano Oct Detector spectral response matching Hautefeuille et al. J. of Crystal Growth (in press) Emission Absorption  Emission and absorption spectra do not overlap » emitted light is not re-absorbed  Emission spectra shifted to lower energies  LYSO: excitation [nm] =262, 293, 357 Max. emission [nm] =398, 435

Olof Tengblad R3B colaboration: Milano Oct Emission spectra Max. emission [nm] Decay time[ns] CsI(Tl) BGO CsI pure31516 LYSO (Ce) CsI(Na) NaI(Tl) LaBr 3 (Ce)38016 LaCl 3 (Ce)35028 NaI(Tl) BGO CsI(Tl) LYSOLaBr 3

Olof Tengblad R3B colaboration: Milano Oct Scintillators W.W. Moses NIMA 487 (2002) 123  LYSO (Lu 1.8 Y 0.2 SiO 5 :Ce) Light output photons/MeV Decay time 45-60ns Density 7.1 g/cm 2  LaBr 3 (:Ce) Light output photons/MeV Decay time 16ns Density 5.3 g/cm 2

Olof Tengblad R3B colaboration: Milano Oct SRIM simulations: protons  Materials: LYSO(:Ce) + LaBr 3 (:Ce)  Thickness: 30mm + 20mm  Monte Carlo: SRIM 2003 E  E 1  E 2

Olof Tengblad R3B colaboration: Milano Oct Energy resolution          E +  E? protons of 200MeV deposit an energy of: 30mm LYSO= 67.44±1.77 MeV 20mm LaBr 3 = 43.50±3.11MeV  200±7MeV (  E/E=3.5%)  200±10MeV (  E/E=5%)

Olof Tengblad R3B colaboration: Milano Oct Gamma absorption  Minimum absorption for  ~5MeV  55% of  absorbed in 30mm LYSO (Prelude)

Olof Tengblad R3B colaboration: Milano Oct Second Conclusion  Protons Two detectors are required to detect 300 MeV protons The energy of the incident protons can be estimated with an error of ~3-4% with the LYSO + LaBr 3 (Ce) solution  Gammas Most of the energy of the gammas is deposited around the first hit, why this should happen in the first layer! 55% of  are absorbed in 30mm LYSO when the energy of the incident gammas is 5MeV >55% of  are absorbed for E ≠ 5MeV in 30mm LYSO The rest will be absorbed in the second layer If first gamma detected in second layer; event discarded However, the gamma resolution in LYSO is about 6% If this  -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 Final Conclusion  To obtain the optimum situation both for protons and gammas; First crystal layer relatively thick and of a material with excellent gamma resolution,  LaBr 3 (Ce) of 30 mm  = 380nm decaytime= 16ns Second 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.  LaCl 3 (Ce) of 150 mm  = 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 LaCl 3 (Ce) or one could combine the LaBr 3 (Ce) with pure CsI as a cheaper solution.

Olof Tengblad R3B colaboration: Milano Oct Tests Two H8500 Flat panel Photomultiplier tube 8x8 MPET-H8500 readout interface Two scintillator arrays : BrilLanCe 380 Full detection area 2”x 2”, 4x4x30 mm 3, encapsulated in Al housing, 3mm glass window 10x10 crystals PreLuDe 420 Full detection area 2”x 2”, 4x4x30 mm 3 12x12 crystals

Olof Tengblad R3B colaboration: Milano Oct Prelude420(60mm) vs CsI(90mm) Protons: Deposit energy Protons: Range in material Gamma: Absorption vs energy

Olof Tengblad R3B colaboration: Milano Oct LaBr 3 (:Ce) different thicknesses Protons: Deposit energy Protons: Range in material Gamma: Absorption vs energy

Olof Tengblad R3B colaboration: Milano Oct mm crystal Protons: Deposit energy Protons: Range in material Gamma: Absorption vs energy

Olof Tengblad R3B colaboration: Milano Oct CsI 90 – 200 mm Protons: Deposit energy Protons: Range in material Gamma: Absorbtion vs energy