Measuring the optical scattering length of scintillator crystals

Cecília O. Steinbach, Ferenc Ujhelyi, E. Lörincz

Research output: Contribution to journalArticle

1 Citation (Scopus)

Abstract

A novel method is presented to determine the optical scattering length in scintillator crystals by directly measuring the scattered light power. It enables to eliminate the large uncertainties in deriving scattering lengths fromthe measured transmittivity using literature data for the index of refraction ("indirectmeasurement"). Using the new method, we distinguish the fluorescent and non-fluorescent part of the optical response of the LYSO scintillators that are widely used in PET detectors. Below 420 nm the scattered intensity mainly stems fromfluorescence while above this wavelength it is due to elastic or inelastic scattering. The latter is strongly dependent on the crystals' defect properties. Scattering lengths at 405 nm are in the range of 1 to 2 m and vary from sample to sample even from the same vendor. In the non-fluorescent regime, Rayleigh scattering of the studied sample measured at 532 nm shows strong orientation dependence. The average scattering length determined by the direct method is 29±3 m (as compared to 0.02 to 0.5 m derived from indirect measurement), i.e. orders of magnitude larger than the typical crystal dimensions. Therefore, in contrast to the widespread belief in the literature, scattering in LYSO crystal scintillators has potentially negligible effect on the operation of PET systems, at least in the non-fluorescent regime.

Original languageEnglish
Article number2346027
Pages (from-to)2456-2463
Number of pages8
JournalIEEE Transactions on Nuclear Science
Volume61
Issue number5
DOIs
Publication statusPublished - Oct 1 2014

Keywords

  • Light scattering
  • Monte Carlo simulations
  • PET
  • Scattering length
  • Scintillation detectors

ASJC Scopus subject areas

  • Nuclear and High Energy Physics
  • Nuclear Energy and Engineering
  • Electrical and Electronic Engineering

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