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Title: On the Relationship Between Scintillation Anisotropy and Crystal Structure in Pure Crystalline Organic Scintillator Materials

We report the scintillation anisotropy effect for proton recoil events has been investigated in five pure organic crystalline materials: anthracene, trans-stilbene, p-terphenyl, bibenzyl, and diphenylacetylene. These measurements include characterization of the scintillation response for one hemisphere of proton recoil directions in each crystal. In addition to standard measurements of the total light output and pulse shape at each angle, the prompt and delayed light anisotropies are analyzed, allowing for investigation of the singlet and triplet molecular excitation behaviors independently. This work provides new quantitative and qualitative observations that make progress toward understanding the physical mechanisms behind the scintillation anisotropy. These measurements show that the relationship between the prompt and delayed light anisotropies is correlated with crystal structure, as it changes between the pi-stacked crystal structure materials (anthracene and p-terphenyl) and the herringbone crystal structure materials (stilbene, bibenzyl, and diphenylacetylene). The observations are consistent with a model in which there are preferred directions of kinetic processes for the molecular excitations. Finally, these processes and the impact of their directional dependencies on the scintillation anisotropy are discussed.
Authors:
 [1] ;  [2] ;  [2]
  1. Univ. of Michigan, Ann Arbor, MI (United States). Nuclear Engineering and Radiological Sciences Department
  2. Sandia National Lab. (SNL-CA), Livermore, CA (United States)
Publication Date:
Report Number(s):
SAND-2018-5256J
Journal ID: ISSN 0018-9499; 663183
Grant/Contract Number:
AC04-94AL85000; NA0000979; NA000352
Type:
Accepted Manuscript
Journal Name:
IEEE Transactions on Nuclear Science
Additional Journal Information:
Journal Volume: 65; Journal Issue: 6; Journal ID: ISSN 0018-9499
Publisher:
IEEE
Research Org:
Sandia National Lab. (SNL-CA), Livermore, CA (United States)
Sponsoring Org:
USDOE National Nuclear Security Administration (NNSA), Office of Defense Nuclear Nonproliferation (NA-20)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; Neutron radiation effects; neutrons; scintillators; solid scintillation detectors
OSTI Identifier:
1441478

Schuster, Patricia, Feng, Patrick, and Brubaker, Erik. On the Relationship Between Scintillation Anisotropy and Crystal Structure in Pure Crystalline Organic Scintillator Materials. United States: N. p., Web. doi:10.1109/TNS.2018.2833030.
Schuster, Patricia, Feng, Patrick, & Brubaker, Erik. On the Relationship Between Scintillation Anisotropy and Crystal Structure in Pure Crystalline Organic Scintillator Materials. United States. doi:10.1109/TNS.2018.2833030.
Schuster, Patricia, Feng, Patrick, and Brubaker, Erik. 2018. "On the Relationship Between Scintillation Anisotropy and Crystal Structure in Pure Crystalline Organic Scintillator Materials". United States. doi:10.1109/TNS.2018.2833030.
@article{osti_1441478,
title = {On the Relationship Between Scintillation Anisotropy and Crystal Structure in Pure Crystalline Organic Scintillator Materials},
author = {Schuster, Patricia and Feng, Patrick and Brubaker, Erik},
abstractNote = {We report the scintillation anisotropy effect for proton recoil events has been investigated in five pure organic crystalline materials: anthracene, trans-stilbene, p-terphenyl, bibenzyl, and diphenylacetylene. These measurements include characterization of the scintillation response for one hemisphere of proton recoil directions in each crystal. In addition to standard measurements of the total light output and pulse shape at each angle, the prompt and delayed light anisotropies are analyzed, allowing for investigation of the singlet and triplet molecular excitation behaviors independently. This work provides new quantitative and qualitative observations that make progress toward understanding the physical mechanisms behind the scintillation anisotropy. These measurements show that the relationship between the prompt and delayed light anisotropies is correlated with crystal structure, as it changes between the pi-stacked crystal structure materials (anthracene and p-terphenyl) and the herringbone crystal structure materials (stilbene, bibenzyl, and diphenylacetylene). The observations are consistent with a model in which there are preferred directions of kinetic processes for the molecular excitations. Finally, these processes and the impact of their directional dependencies on the scintillation anisotropy are discussed.},
doi = {10.1109/TNS.2018.2833030},
journal = {IEEE Transactions on Nuclear Science},
number = 6,
volume = 65,
place = {United States},
year = {2018},
month = {5}
}