Characterization of deuterated stilbene: an organic scintillator for neutron spectroscopy

Gaughan, Natalie

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https://hdl.handle.net/2142/113794 Copy

Description

Title

Characterization of deuterated stilbene: an organic scintillator for neutron spectroscopy

Author(s)

Gaughan, Natalie

Issue Date

2021-07-28

Director of Research (if dissertation) or Advisor (if thesis)

Di Fulvio, Angela

Committee Member(s)

Heuser, Brent

Department of Study

Nuclear, Plasma, & Rad Engr

Discipline

Nuclear, Plasma, Radiolgc Engr

Degree Granting Institution

University of Illinois at Urbana-Champaign

Degree Name

M.S.

Degree Level

Thesis

Keyword(s)

• radiation detection
• neutron spectroscopy
• organic scintillators
• deuterated scintillators
• deuterated stilbene

Abstract

Deuterated stilbene stilbene-d12 is a recently-developed organic scintillator whose neutron light output characterization in the 0.5 - 4.4. MeV energy range is reported in this thesis, for the first time. A time-of-flight experiment was performed to obtain the light output response of stilbene-d12 to quasi-monoenergetic neutrons. The light output response, which is the relationship between energy deposited by deuteron recoils produced by neutron scattering and light emitted in the scintillator, is essential to determine the incident neutron spectrum. The experimentally-obtained light output function was used to simulate the response matrix of stilbene-d12 to monoenergetic neutrons, from 0.5 to 20 MeV, using MCNPX-PoliMi. The simulated response matrix was then used to unfold the incident energy spectrum from the measured light-output response. The unfolding was performed using an iterative Bayesian method that also allows an estimation of the uncertainty associated with the unfolded spectrum. Stilbene-d12 and 1H-stilbene were both used to unfold spectra from DT and 239PuBe sources, with the spectra obtained from stilbene-d12 better resembling the ground truth spectra compared to 1H-stilbene spectra. The intrinsic efficiency of the stilbene-d12 detector to neutrons was also measured experimentally, using a 14.1 MeV DT generator as the neutron source, and it was found to be 55% ± 1%. The simulated efficiency of 56% ± 0.004% is in good agreement with the measured value. In this work, we showed that stilbene-d12 is capable of fine spectrum unfolding and displays pulse shape discrimination capability to distinguish neutron from gamma-ray pulses comparably or better than 1H-stilbene. The results of the time-of-flight experiment, which are presented in chapter 2, have also been submitted for publication in Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment with the title “Characterization of stilbene-d12 for neutron spectroscopy without time of flight” by Natalie Gaughan, Jianxin Zhou, Frederick Becchetti, Ramon O.Torres-Isea, Michael Febbraro, Natalia Zaitseva, and Angela Di Fulvio.

Graduation Semester

2021-12

Type of Resource

Thesis

Permalink

http://hdl.handle.net/2142/113794

Copyright and License Information

©2021 by Natalie Gaughan. All rights reserved.

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