An inner-crystal neutron-scatter camera: Monte carlo simulation

Ajin Jo, Won Ho Lee

Research output: Contribution to journalArticle

Abstract

Neutron energy emitted from special nuclear materials (SNMs) can be measured by using neutronproton scattering; also, the scattering angle can be calculated from the ratio of the scattered energy to the incident energy. By using position and energy information, we can image the original source position by using the backprojection and list-mode maximum-likelihood expectation maximization (MLEM) method. In this paper, we propose an inner-crystal neutron scatter camera system in which the detectors are not separated to obtain interactions at a variety of scatter angles; based on this system, we analyzed the characteristics of the corresponding neutron-scattering camera. The factors that affected the neutron-scatter image were the neutron velocity after scattering, the cut-off level of the time of flight (ToF), and the width of the cones used for image reconstruction. To determine the optimal point for the reconstruction of an image, we estimated the performance of the system by using the figure of merit (FoM). The optimal neutron-velocity (d/ToF) was ~0.3 × 107 m/s according to our simulation result, while the optimal cut-off level of the ToF was 4 ns as the latter minimized the noise while maintaining the required efficiency. The widths of the cones (ε) also affected the full width at half maximum (FWHM) and the noise of the image. In terms of a simple source-geometry, whereby concepts such as “point source” were used, a large e value was suitable to achieve noise reduction; however, regarding the complicated source geometry, a small e value was favorable for precise reconstruction of the original source geometry for both the backprojection and the list-mode MLEM methods.

Original languageEnglish
Pages (from-to)1126-1131
Number of pages6
JournalJournal of the Korean Physical Society
Volume68
Issue number9
DOIs
Publication statusPublished - 2016 May 1

Fingerprint

cameras
neutrons
crystals
simulation
lists
cones
cut-off
geometry
scattering
energy
image reconstruction
noise reduction
figure of merit
point sources
neutron scattering
detectors
interactions

Keywords

  • MLEM
  • Neutron-scatter camera

ASJC Scopus subject areas

  • Physics and Astronomy(all)

Cite this

An inner-crystal neutron-scatter camera : Monte carlo simulation. / Jo, Ajin; Lee, Won Ho.

In: Journal of the Korean Physical Society, Vol. 68, No. 9, 01.05.2016, p. 1126-1131.

Research output: Contribution to journalArticle

@article{a5a92208be8144d0a73afcd803c37912,
title = "An inner-crystal neutron-scatter camera: Monte carlo simulation",
abstract = "Neutron energy emitted from special nuclear materials (SNMs) can be measured by using neutronproton scattering; also, the scattering angle can be calculated from the ratio of the scattered energy to the incident energy. By using position and energy information, we can image the original source position by using the backprojection and list-mode maximum-likelihood expectation maximization (MLEM) method. In this paper, we propose an inner-crystal neutron scatter camera system in which the detectors are not separated to obtain interactions at a variety of scatter angles; based on this system, we analyzed the characteristics of the corresponding neutron-scattering camera. The factors that affected the neutron-scatter image were the neutron velocity after scattering, the cut-off level of the time of flight (ToF), and the width of the cones used for image reconstruction. To determine the optimal point for the reconstruction of an image, we estimated the performance of the system by using the figure of merit (FoM). The optimal neutron-velocity (d/ToF) was ~0.3 × 107 m/s according to our simulation result, while the optimal cut-off level of the ToF was 4 ns as the latter minimized the noise while maintaining the required efficiency. The widths of the cones (ε) also affected the full width at half maximum (FWHM) and the noise of the image. In terms of a simple source-geometry, whereby concepts such as “point source” were used, a large e value was suitable to achieve noise reduction; however, regarding the complicated source geometry, a small e value was favorable for precise reconstruction of the original source geometry for both the backprojection and the list-mode MLEM methods.",
keywords = "MLEM, Neutron-scatter camera",
author = "Ajin Jo and Lee, {Won Ho}",
year = "2016",
month = "5",
day = "1",
doi = "10.3938/jkps.68.1126",
language = "English",
volume = "68",
pages = "1126--1131",
journal = "Journal of the Korean Physical Society",
issn = "0374-4884",
publisher = "Korean Physical Society",
number = "9",

}

TY - JOUR

T1 - An inner-crystal neutron-scatter camera

T2 - Monte carlo simulation

AU - Jo, Ajin

AU - Lee, Won Ho

PY - 2016/5/1

Y1 - 2016/5/1

N2 - Neutron energy emitted from special nuclear materials (SNMs) can be measured by using neutronproton scattering; also, the scattering angle can be calculated from the ratio of the scattered energy to the incident energy. By using position and energy information, we can image the original source position by using the backprojection and list-mode maximum-likelihood expectation maximization (MLEM) method. In this paper, we propose an inner-crystal neutron scatter camera system in which the detectors are not separated to obtain interactions at a variety of scatter angles; based on this system, we analyzed the characteristics of the corresponding neutron-scattering camera. The factors that affected the neutron-scatter image were the neutron velocity after scattering, the cut-off level of the time of flight (ToF), and the width of the cones used for image reconstruction. To determine the optimal point for the reconstruction of an image, we estimated the performance of the system by using the figure of merit (FoM). The optimal neutron-velocity (d/ToF) was ~0.3 × 107 m/s according to our simulation result, while the optimal cut-off level of the ToF was 4 ns as the latter minimized the noise while maintaining the required efficiency. The widths of the cones (ε) also affected the full width at half maximum (FWHM) and the noise of the image. In terms of a simple source-geometry, whereby concepts such as “point source” were used, a large e value was suitable to achieve noise reduction; however, regarding the complicated source geometry, a small e value was favorable for precise reconstruction of the original source geometry for both the backprojection and the list-mode MLEM methods.

AB - Neutron energy emitted from special nuclear materials (SNMs) can be measured by using neutronproton scattering; also, the scattering angle can be calculated from the ratio of the scattered energy to the incident energy. By using position and energy information, we can image the original source position by using the backprojection and list-mode maximum-likelihood expectation maximization (MLEM) method. In this paper, we propose an inner-crystal neutron scatter camera system in which the detectors are not separated to obtain interactions at a variety of scatter angles; based on this system, we analyzed the characteristics of the corresponding neutron-scattering camera. The factors that affected the neutron-scatter image were the neutron velocity after scattering, the cut-off level of the time of flight (ToF), and the width of the cones used for image reconstruction. To determine the optimal point for the reconstruction of an image, we estimated the performance of the system by using the figure of merit (FoM). The optimal neutron-velocity (d/ToF) was ~0.3 × 107 m/s according to our simulation result, while the optimal cut-off level of the ToF was 4 ns as the latter minimized the noise while maintaining the required efficiency. The widths of the cones (ε) also affected the full width at half maximum (FWHM) and the noise of the image. In terms of a simple source-geometry, whereby concepts such as “point source” were used, a large e value was suitable to achieve noise reduction; however, regarding the complicated source geometry, a small e value was favorable for precise reconstruction of the original source geometry for both the backprojection and the list-mode MLEM methods.

KW - MLEM

KW - Neutron-scatter camera

UR - http://www.scopus.com/inward/record.url?scp=84966283949&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=84966283949&partnerID=8YFLogxK

U2 - 10.3938/jkps.68.1126

DO - 10.3938/jkps.68.1126

M3 - Article

AN - SCOPUS:84966283949

VL - 68

SP - 1126

EP - 1131

JO - Journal of the Korean Physical Society

JF - Journal of the Korean Physical Society

SN - 0374-4884

IS - 9

ER -