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Gamma Rays Rejection in a Gadolinium based Semiconductor Neutron Detector

Kandlakunta, Praneeth
http://rave.ohiolink.edu/etdc/view?acc_num=osu1386883923

Abstract Details

2014, Doctor of Philosophy, Ohio State University, Nuclear Engineering.
Gadolinium (Gd) is a competent neutron conversion material due to its extremely large neutron capture cross-section, which makes it an attractive choice for thermal neutron detection as well as certain medical applications, such as Gd neutron capture therapy (GdNCT). However, the principal secondary particles that generate electron-hole (e-h) pairs in a semiconductor detector following Gd neutron capture are low energy internal conversion electrons (ICEs). Detailed information about the low energy electron spectrum emitted after Gd neutron capture is fundamental for evaluating the conversion efficiency of Gd for neutron detection as well as accurately determining dose delivery to the target and healthy tissues in GdNCT. However, the suitability of Gd for neutron conversion over other competing materials such as boron (B) and lithium (Li) is still debated owing to issues associated with the low energy of ICEs and high gamma interaction probability of Gd. The detection of low energy ICEs, although emitted in abundance, is prone to be interfered by external and/or internal gamma rays, such as the activated 43 keV K-X rays, given the high atomic number (Z) of Gd. A method for separation of gamma rays is thus highly essential when Gd is used in the format of thin film semiconductor detector for neutron detection. The objectives of this research are, to study the feasibility of using Gd for neutron detection, and to develop a gamma ray rejection scheme for a Gd based semiconductor neutron detector and investigate the efficacy of the rejection scheme for separation of gamma rays. In this dissertation, a gamma ray rejection scheme designed using two identical semiconductor detectors (twin-detector), Gd neutron conversion layer and polyethylene electron separator has been investigated. Monte Carlo (MC) simulations of neutron and gamma ray interaction with the twin-detector structure were extensively performed. The simulation results validated the hypothesis of the rejection method and demonstrated effective separation of neutron induced ICEs from gamma rays. A comprehensive set of experiments were performed to evaluate the neutron and gamma sensitivity of Gd and test the practicability of the proposed neutron-gamma (n-g) separation method. The experimental results agreed well with simulations and supported the feasibility of the gamma rejection scheme. Results further established the suitability of Gd for neutron detection, indicating a neutron sensitivity much superior to its gamma sensitivity, and demonstrated the effectiveness of n-g separation using the proposed method.
Lei Cao (Advisor)
Don Miller (Committee Member)
Thomas Blue (Committee Member)
Shaurya Prakash (Committee Member)
171 p.
Nuclear Engineering
Gadolinium; Semiconductor neutron detector; Gamma ray discrimination; Internal conversion electrons

Recommended Citations

Citations

  • Kandlakunta, P. (2014). Gamma Rays Rejection in a Gadolinium based Semiconductor Neutron Detector [Doctoral dissertation, Ohio State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=osu1386883923

    APA Style (7th edition)

  • Kandlakunta, Praneeth. Gamma Rays Rejection in a Gadolinium based Semiconductor Neutron Detector. 2014. Ohio State University, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=osu1386883923.

    MLA Style (8th edition)

  • Kandlakunta, Praneeth. "Gamma Rays Rejection in a Gadolinium based Semiconductor Neutron Detector." Doctoral dissertation, Ohio State University, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=osu1386883923

    Chicago Manual of Style (17th edition)

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This open access ETD is published by The Ohio State University and OhioLINK.