Characterization of high-energy quasi-monoenergetic neutron energy spectra and ambient dose equivalents of 80-389 MeV ⁷Li(p,n) reactions using a time-of-flight method

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• 作者：Yosuke Iwamoto^a ; ^{iwamoto.yosuke@jaea.go.jp" class="auth_mail" title="E-mail the corresponding author} ; Masayuki Hagiwara^b ; ⁱ ; Daiki Satoh^a ; Shouhei Araki^c ; Hiroshi Yashima^d ; Tatsuhiko Sato^a ; Akihiko Masuda^e ; Tetsuro Matsumoto^e ; Noriaki Nakao^f ; Tatsushi Shima^g ; Tadahiro Kin^c ; Yukinobu Watanabe^c ; Hiroshi Iwase^b ; ⁱ ; Takashi Nakamura^f ; h
• 关键词：Quasi-monoenergetic neutron field ; 7Li(p ; n) reaction ; Time of flight ; Subtraction method ; Ambient dose equivalent
• 刊名：Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment
• 出版年：2015
• 出版时间：21 December 2015
• 年：2015
• 卷：804
• 期：Complete
• 页码：50-58
• 全文大小：1153 K

文摘

We completed a series of measurements on mono-energetic neutron energy spectra of the ⁷Li(p,n) reaction with 80–389-MeV protons in the 100-m time-of-flight (TOF) tunnel at the Research Center for Nuclear Physics cyclotron facility. For that purpose, we measured neutron energy spectra of the 80-, 100- and 296-MeV proton incident reactions, which had not been investigated in our previous studies. The neutron peak intensity was 0.9–1.1×10¹⁰ neutrons/sr/µC in the incident proton energy region of 80–389 MeV, and it was almost independent of the incident proton energy. The contribution of peak intensity of the spectrum to the total intensity integrated with energies above 3 MeV varied between 0.38 and 0.48 in the incident proton energy range of 80–389 MeV. To consider the correction required to derive a response in the peak region from the measured total responses of neutron monitors in the 100-m TOF tunnel, we proposed the subtraction method using energy spectra between 0° and 25°. The normalizing factor k against 25° neutron fluence to equalize it to 0° neutron fluence in the continuum region ranges from 0.74 to 1.02 depending on the incident proton energy and angle measured. Even without the TOF method, the subtraction method with the k factor almost decreases the response in the continuum region of a neutron spectrum against the total response of neutron monitors.