Inorganic scintillators Trends and perspectives Paul Lecoq CERN, - - PowerPoint PPT Presentation

• P. Lecoq CERN

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February 2015

FCC meeting, CERN, February 3d, 2015

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

• P. Lecoq CERN

February 2015

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FCC meeting, CERN, February 3d, 2015

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…)

• P. Lecoq CERN

February 2015

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FCC meeting, CERN, February 3d, 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

• P. Lecoq CERN

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FCC meeting, CERN, February 3d, 2015

q 2

SiPM Crystal electronics

g

Dt tkth pe = Dt

Conversion depth

+ tk’ ph

Scintillation process

+ ttransit

Transit time jitter

+ tSPTR

Single photon time spread

+ tTDC

TDC conversion time

Random deletion 1

Absorption Self-absorption

Random deletion 2

SiPM PDE

Unwanted pulses 2

DCR

Unwanted pulses 1

DCR, cross talk Afterpulses

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New research directions

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

• P. Lecoq et al, IEEE Trans. Nucl. Sci. 57 (2010) 2411-2416

2. The light transport in the crystal



Time spread related to different light propagation modes

3. The light extraction efficiency (LYLO)



Impact on photostatistics



Weights the distribution of light propagation modes

• P. Lecoq CERN

February 2015

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FCC meeting, CERN, February 3d, 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?????

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Light generation in a scintillator

Rare Earth

4f 5d

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February 2015

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 Wide emission spectrum from UV

to IR

 Ultrafast emission in the ps range  Independant of temperature  Independant of defects  Absolute Quantum Yield

Whn/Wphonon = 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

Hot intraband luminescence

• M. Korzhik, P. Lecoq, A. Vasil’ev, SCINT2013 paper

TNS-00194-2013

• P. Lecoq CERN

February 2015

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FCC meeting, CERN, February 3d, 2015

CeF3 hot intraband luminescence

• V. Nagirnyi, S. Omelkov, Tartu, Estonia

Fast interband hole luminescence < 200ps Fast 5ns CeF3 luminescence Fast interband e- luminescence < 200ps Regular 20ns CeF3 luminescence

Tartu electron gun, 200keV, 200ps

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Transient absorption

M-Korzhik

• P. Lecoq CERN

February 2015

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Transient absorption

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

• 5

5 10 15

• 0,02

0,00 0,02 0,04 0,06 0,08 0,10 0,12

DD Dt, ps

420 nm

M-Korzhik

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February 2015

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FCC meeting, CERN, February 3d, 2015

Transient absorption

M-Korzhik

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CdSe Nanosheets

Exciton/biexciton emission obtained in the lab using LSO + CdSe nano deposition excited with blue laser. Electron pulse excitation experiments to come.

 Stimulated photoluminescence due to exciton quantum

confimenet in CdSe nanoplatelets

 100mm layer of CdSe nanoplatelets deposited on 1mm

thick LSO crystal by J. Grim, IIT, Genova

• P. Lecoq, J.Grim, I.Moreels, SCINT conference

Berkeley, June 2015

• R. Turtos Matinez, CERN

525nm

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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

• P. Lecoq CERN

February 2015

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FCC meeting, CERN, February 3d, 2015

Photonic crystals

Crystal Crystal- air interface with PhC grating: θ>θc Total Reflection at the interface Extracted Mode θ>θc

Nanostructured interface allowing to couple light propagation modes inside and outside the crystal

air θ>θc

• P. Lecoq CERN

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 Use large LYSO crystal: 10x10mm2 to avoid edge

effects

 6 different patches (2.6mm x 1.2mm) and 1

(1.2mm x 0.3mm) of different PhC patterns 0° 45°

Photonic crystals

• A. Knapitsch et al, “Photonic crystals: A novel approach to enhance the light output of scintillation based detectors,

NIM A268, pp.385-388, 2011

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FCC meeting, CERN, February 3d, 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

–

• 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%

 Can be used to redirect in the

direction of the photodetector >50%

• f the light emitted at large angle

• P. Lecoq CERN

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New production technologies

 Micro-Pulling-Down: Marie Curie Rise-INTELUM

project recently approuved – CERN coordinator

Ce doped LuAG Sintillator undoped LuAG Cerenkov 30cm

Ø 2mm

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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

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FCC meeting, CERN, February 3d, 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

Courtesy R. Williams, Wake Forest University

60 ps ZnO:Ga powder

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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….