MOVED TO A LATER DATE
According to the Rector’s No. 28 of March 13, 2020, the seminar has been moved to a later date.
Participants will be notified of the new date of the seminar.
The organizers would like to apologize to the speaker and seminar participants.
Ewa Stępień and Paweł Moskal
The 10ps TOFPET challenge requires a parallel effort on all the components of the detector chain (crystal, photodetector, readout electronics). We have demonstrated that even with the best presently available SiPM photodetectors, the most popular scintillators for PET (L(Y)SO, L(G)SO, LaBr3) are limited in their timing performance at low energy and that a mechanism to produce a few hundred prompt photons on top of the scintillation signal is necessary in order to reach 10ps coincidence time resolution (CTR) at 511keV.
This contribution describes our work for developing a metamaterial-based scintillator block having these characteristics. A quantitative justification will be given, based on our measurements, for a combination of L(Y)SO, in form of block, plates or fibers with:
ZnO rods of different sizes
CdSe nanoplatelets, 35x8x1nm3, produced by wet technology, taking advantage of the 1D quantum confinement, allowing coherent multi-excitonic emission with a <1ps rise time and 290ps decay time
ZnO:Ga quantum dots, produced by photo-induced precipitation with calcination in air and Ar/H2 atmosphere, with <1ps rise time and 504ps decay time,
CsPbBr3 perovskite quantum dots showing a bright multiexcitonic emission with rise time of <1ps, and a decay time of 320ps (≈50%) and 2.48ns (≈50%)
Simulation results for different, but not yet optimized, geometrical configurations of the metamaterial structure show that an energy leakage from LYSO to the fast component of the metastructure of ≥ 100keV can be obtained for about 20% of the 511keV γ-rays fully converted in the metastructure, inducing the production of ≈250 prompt photons on CdSe nanoplatelets on top of the LYSO scintillation signal.
Evidence of this prompt peak has been obtained in our lab on a simple heterostructure made of 200micron thick LYSO plates covered by CdSe nanoplatelets layers deposited by drop casting. Results on more metastructures configurations will be given at the time of the conference.