Inorganic scintillators Trends and perspectives Paul Lecoq CERN, Geneva This work is performed in the frame of the ERC Advanced Grant Agreement N°338953 – TICAL FCC meeting, CERN, February 3 d , 2015 1 February 2015 P. Lecoq CERN
25 years of SCINT community actions New crystals development – PWO – La halide family – LSO, LYSO, LGSO, LuAP, LuYAP, LuAG , …. Main emphasis (application driven: HEP & MI) was on: – Understanding the material High light yield Good energy resolution (non-uniformity) Short decay time (for high event rate) Good radiation hardness (defect studies, compensation doping) – Developping/adapting production technologies Czokralsky and Bridgeman for reacing desired specifications Investigating new technologies (mPD, ceramics,thin films, nano…) FCC meeting, CERN, February 3 d , 2015 2 P. Lecoq CERN February 2015
Why fast timing in HEP? Search for rare events implies High luminosity accelerators – Rate problems – Pile-up Time of Flight techniques can alleviate the pile-up problem and help improving energy resolution, but: – Current state of the art for Alice expt: 75ps – Current state of the art for PET demonstrators: 140ps Need for a finely segmented calorimeter with 10ps time resolution FCC meeting, CERN, February 3 d , 2015 3 P. Lecoq CERN February 2015
Crystal SiPM electronics g q D t 2 D t t kth pe = + t k ’ ph + t transit + t SPTR + t TDC Scintillation Transit time Single photon TDC Conversion depth process jitter time spread conversion time Random deletion 1 Unwanted pulses 1 Absorption DCR, cross talk Self-absorption Afterpulses Random deletion 2 Unwanted pulses 2 SiPM PDE DCR FCC meeting, CERN, February 3 d , 2015 4 P. Lecoq CERN February 2015
New research directions P. Lecoq et al, IEEE Trans. Nucl. Sci. 57 (2010) 2411-2416 Besides all factors related to photodetection and readout electronics the scintillator contributes to the time and energy resolution through: 1. The scintillation mechanism Light yield, Rise time, Decay time 2. The light transport in the crystal Time spread related to different light propagation modes The light extraction efficiency (LY LO) 3. Impact on photostatistics Weights the distribution of light propagation modes FCC meeting, CERN, February 3 d , 2015 5 P. Lecoq CERN February 2015
Ways to a faster rise time? Rise time is to a large extent related to the multiple scattering and thermalization of hot primary e-h pairs More studies needed for self activated scintillators – Probability for low energy transfer from ionizing radiation – Direct excitation of the luminescent center – It would be interesting to measure the rise time of PWO, BGO, CeF3 Cross luminescence: Core-Valence luminescence – Sub ns rise time and decay time – But UV-VUV emission (not maching SiPM QE) High donor band: ZnO, CuI , PbI2… – Derenzo, NIMA 486 (2002) 214-219 Cerenkov Quantum dots????? FCC meeting, CERN, February 3 d , 2015 6 P. Lecoq CERN February 2015
Light generation in a scintillator 5d Rare Earth 4f FCC meeting, CERN, February 3 d , 2015 7 P. Lecoq CERN February 2015
Hot intraband luminescence Wide emission spectrum from UV to IR Ultrafast emission in the ps range Independant of temperature Independant of defects Absolute Quantum Yield W h n /W phonon = 10 -8 /(10 -11 -10 -12 ) ≈ 10 -3 to 10 -4 ph/eh pair Higher yield if structures or dips in CB? Interesting to look at CeF3 M. Korzhik, P. Lecoq, A. Vasil’ev , SCINT2013 paper TNS-00194-2013 FCC meeting, CERN, February 3 d , 2015 8 P. Lecoq CERN February 2015
CeF 3 hot intraband luminescence Fast 5ns CeF3 luminescence Tartu electron gun, 200keV, 200ps Regular 20ns CeF3 luminescence Fast interband hole luminescence < 200ps Fast interband e - luminescence < 200ps V. Nagirnyi, S. Omelkov, Tartu, Estonia FCC meeting, CERN, February 3 d , 2015 9 P. Lecoq CERN February 2015
Transient absorption M-Korzhik FCC meeting, CERN, February 3 d , 2015 10 P. Lecoq CERN February 2015
Transient absorption 0,12 0,10 420 nm 0,08 0,06 D D 0,04 0,02 0,00 -0,02 -5 0 5 10 15 D t, ps Experimental bench to prove the concept Two photons(2,97+3.16eV) absorption in 1 cm thick PWO R&D to combine ionization and transient absorption is planned within AIDA-II and TICAL: 4D Time Imaging Calorimeter ERC project M-Korzhik FCC meeting, CERN, February 3 d , 2015 11 P. Lecoq CERN February 2015
Transient absorption M-Korzhik FCC meeting, CERN, February 3 d , 2015 12 P. Lecoq CERN February 2015
CdSe Nanosheets Stimulated photoluminescence due to exciton quantum confimenet in CdSe nanoplatelets 100 m m layer of CdSe nanoplatelets deposited on 1mm thick LSO crystal by J. Grim, IIT, Genova 525nm Exciton/biexciton emission obtained in the lab using LSO + CdSe nano deposition excited with blue laser. Electron pulse excitation experiments to come. P. Lecoq, J.Grim, I.Moreels, SCINT conference R. Turtos Matinez, CERN Berkeley, June 2015 FCC meeting, CERN, February 3 d , 2015 13 P. Lecoq CERN February 2015
Light Transport – -49 ° < < 49 ° Fast forward detection 17.2% – 131 ° < < 229 ° Delayed back detection 17.2% – 57 ° < < 123 ° Fast escape on the sides 54.5% – 49 ° < < 57 ° and 123 ° < < 131 ° infinite bouncing 11.1% Improving light extraction efficiency at first hit on coupling face to photodetector is the key FCC meeting, CERN, February 3 d , 2015 14 P. Lecoq CERN February 2015
Photonic crystals Nanostructured interface allowing to couple light propagation modes inside and outside the crystal Crystal- air interface with PhC grating: Crystal air θ > θ c θ > θ c Total Reflection θ > θ c at the interface Extracted Mode FCC meeting, CERN, February 3 d , 2015 15 P. Lecoq CERN February 2015
Photonic crystals 0° 45° Use large LYSO crystal: 10x10mm 2 to avoid edge effects 6 different patches (2.6mm x 1.2mm) and 1 (1.2mm x 0.3mm) of different PhC patterns A. Knapitsch et al, “Photonic crystals: A novel approach to enhance the light output of scintillation based detectors, NIM A268, pp.385-388, 2011 FCC meeting, CERN, February 3 d , 2015 16 P. Lecoq CERN February 2015
Chiral nanophotonic waveguide Controlling the flow of light with nanophotonic waveguides Transverse quantum confinement of guided photons strong spin – orbit coupling Allows scattering of light by a nonoparticle at the surface of the nanofiber to be redirected in the direction of the fiber Can be used to redirect in the direction of the photodetector >50% -49 ° < < 49 ° Fast forward detection – 17.2% of the light emitted at large angle 131 ° < < 229 ° Delayed back detection – 17.2% 57 ° < < 123 ° Fast escape on the sides – 54.5% FCC meeting, CERN, February 3 d , 2015 49 ° < < 57 ° and 123 ° < < 131 ° 17 – P. Lecoq CERN February 2015 infinite bouncing 11.1%
New production technologies Micro-Pulling-Down: Marie Curie Rise-INTELUM project recently approuved – CERN coordinator Ø 2mm 30cm Ce doped LuAG undoped LuAG Sintillator Cerenkov FCC meeting, CERN, February 3 d , 2015 18 P. Lecoq CERN February 2015
New production technologies Transparent Ceramics Reduced production cost Increased activator concentration Increased uniformity of doping Improved mechanical properties Production of large transparent samples of various shapes Potential to fabricate phases that can not be grown from melt Courtesy N. Cherepy, S. Payne, LLNL FCC meeting, CERN, February 3 d , 2015 19 P. Lecoq CERN February 2015
New production technologies Thin films – ZnO:Ga thin films on Si(100) are deposited by reactive DC magnetron sputtering of zinc in oxygen/argon mix, followed by vacuum annealing 60 ps ZnO:Ga powder Courtesy R. Williams, Wake Forest University FCC meeting, CERN, February 3 d , 2015 20 P. Lecoq CERN February 2015
Conclusions R&D in inorganic scintillators is moving fast Timing performance is becoming a key R&D focus for many applications (HEP, MI, Homeland security , …) Enabling technologies are being developped – Crystal production – Nanophotonics for the management of optical photons A rapidly moving field with an enormous industrial potential and demand 3D ranging Photo-electronic chips Quantum entanglement and quantum computing Etc …. FCC meeting, CERN, February 3 d , 2015 21 P. Lecoq CERN February 2015
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