AB011. Validation of a spectrometer to measure epi-thermal neutrons using a position sensitive proportional counter—development of pencil-beam epi-thermal neutron source with a deuteron-tritium (DT) neutron source
Abstract

AB011. Validation of a spectrometer to measure epi-thermal neutrons using a position sensitive proportional counter—development of pencil-beam epi-thermal neutron source with a deuteron-tritium (DT) neutron source

Yu Fujiwara, Shingo Tamaki, Sachie Kusaka, Fuminobu Sato, Isao Murata

Division of Sustainable Energy and Environmental Engineering, Department of Engineering, Graduate School of Osaka University, Osaka, Japan

Correspondence to: Isao Murata, PhD. Division of Sustainable Energy and Environmental Engineering, Department of Engineering, Graduate School of Osaka University, Yamada-oka 2-1, Suita, Osaka 565-0871, Japan. Email: murata@see.eng.osaka-u.ac.jp.

Background: Currently, there are many ongoing attempts to utilize an accelerator-based neutron source for boron neutron capture therapy (ABNS-BNCT), which can be installed near hospitals to minimize patient inconvenience. However, ABNS has encountered difficulties in characterizing the irradiation field. Furthermore, there is currently no available method for measuring the energy spectrum in the epi-thermal neutron region that is utilized in BNCT. Within the author’s group, a novel technique has been developed to estimate the neutron spectrum based on a position-sensitive 3He proportional counter. During the validation of this method, it was made clear that neutrons incident from the side surface of the spectrometer had a significant impact on the measurement accuracy. As a result, a new beam shaping assembly (BSA) was designed and constructed with a pre-collimator to suppress the effect of such side-incident neutrons.

Methods: By assuming a deuteron-tritium (DT) neutron source at Osaka University, the design of a pre-collimator that collimates neutron flow to prevent side incidence was carried out. MCNP5 was utilized for the design calculations, and the determination of the following four parameters was completed: (I) material; (II) horizontal length of the pre-collimator; (III) aperture of the pre-collimator; and (IV) distance between the pre-collimator and the epi-thermal neutron column. In addition, two design goals were set as follows: (I) ensure that the percentage of neutrons penetrating the spectrometer from the front surface to the end surface is 99% or more; and (II) ensure that the number of neutron counts is 104 or greater for 5 hours.

Results: Through the determination processes, four parameters were successfully determined: (I) polyethylene; (II) 70 cm; (III) 1.4 cm; and (IV) 300 cm. The neutron beam achieved the design goals.

Conclusions: This study focused on the design of a beam-shaping assembly that is necessary to validate a method for measuring the energy spectrum in the epi-thermal neutron region. The next step is to perform experiments to test the spectrometer’s performance using the present neutron source.

Keywords: Boron neutron capture therapy (BNCT); neutron measurement; beam shaping assembly (BSA); Monte Carlo simulation; collimator system

Acknowledgments

None.

Footnote

Funding: None.

Conflicts of Interest: All authors have completed the ICMJE uniform disclosure form. (available at https://tro.amegroups.com/article/view/10.21037/tro-25-ab011/coif). The authors have no conflicts of interest to declare.

Ethical Statement: The authors are accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved. Also, Ethical approval was not required for this study because it did not involve human or animal participants, nor did it entail the use of personal data.

Open Access Statement: This is an Open Access article distributed in accordance with the Creative Commons Attribution-NonCommercial-NoDerivs 4.0 International License (CC BY-NC-ND 4.0), which permits the noncommercial replication and distribution of the article with the strict proviso that no changes or edits are made and the original work is properly cited (including links to both the formal publication through the relevant DOI and the license). See: https://creativecommons.org/licenses/by-nc-nd/4.0/.

doi: 10.21037/tro-25-ab011
Cite this abstract as: Fujiwara Y, Tamaki S, Kusaka S, Sato F, Murata I. AB011. Validation of a spectrometer to measure epi-thermal neutrons using a position sensitive proportional counter—development of pencil-beam epi-thermal neutron source with a deuteron-tritium (DT) neutron source. Ther Radiol Oncol 2025;9:AB011.

Article Options

Download Citation

Share