隨著大型加速器的蓬勃發展，高能中子的劑量評估方法快速發展且需求殷切。本論文透過引進商用波那球以及自行設計之高靈敏度波那圓柱系統，建立該領域之量測與模擬技術；除透過核研所國家游離輻射標準實驗室完成系統驗證，並應用於宇宙射線誘發中子能譜量測等實務，確認系統之可靠度與使用限制；此外，提出中子偵檢儀器於高能輻射場之校正因子修正方法，彌補國內目前尚欠缺之校正技術缺口。
商用波那球受限於偵檢器體積，量測靈敏度低，應用領域受到侷限。本論文所自行設計之高靈敏度波那圓柱系統，量測靈敏度較商用系統增加約17.9倍；搭配蒙地卡羅程式計算之偵檢器響應函數，可進行從熱中子延升至GeV能量區間之全能域中子能譜量測。惟波那圓柱系統受限於軸向極角不對稱因素，系統響應函數與中子入射方向高度相關；為此，本論文共發展出平面單向、均向與點射源入射等3種模式以為因應。此外，對於國內目前尚欠缺的高能中子輻射場校正技術，本研究結合蒙地卡羅計算方法與國家游離輻射標準實驗室校正結果，提出根據不同輻射場特性所對應之校正因子修正方法，將國家游離輻射標準實驗室中子校正適用能量區間延伸至GeV等級。
本論文以商用波那球系統為標準，有系統地探討高靈敏度波那圓柱中子能譜儀物理特性與適用性。未來使用者將可以商用系統1/4以下的價格建置本中子偵檢系統；此外，本論文所提出的高能輻射場中子偵檢器校正因子修正方法，可讓使用者依據不同輻射場特性，進行快速而又不失準確程度的中子劑量評估方式；此方法除可確保工作人員輻射安全無虞，更可據此節省將中子儀器送往國際高能輻射場進行校正所需之高額費用與冗長時程。
期許本論文研究成果能提供予設施業主與主管機關參考，為國內輻射應用領域略盡棉薄之力。

Bonner spheres are widely used to determine the energy spectrum of a neutron field. With the introduction of high-Z metal in moderator as a neutron multiplier, the effective energy range of Bonner spheres can be extended to GeV neutrons. Because of small active volume of the central probe, the detection efficiency of Bonner spheres is limited and impractical in certain field measurement applications. In this study, a set of Bonner cylinders was fabricated based on a high-efficiency cylindrical 3He proportional counter. The cylindrical arrangement substantially improved the detection efficiency of the spectrometer system, but inevitably yielded an angular dependence on the detector responses. Using a series of calculations and measurements, this study presents a systematic comparison between Bonner spheres and cylinders in terms of their response functions, detection efficiencies, angular dependences and spectrum unfolding.
Besides, neutron dosemeters used for radiation protection purpose are commonly calibrated with 252Cf neutron sources and are used in various workplaces. In this study, the effect of the neutron spectrum on the accuracy of dose measurements was investigated. A set of neutron spectra representing various neutron environments was selected to study the dose responses of a series of Bonner spheres, including standard and extended-range spheres. By comparing 252Cf-calibrated dose responses with reference values based on fluence-to-dose conversion coefficients, this study presents recommendations for neutron field characterization and appropriate correction factors for responses of conventional neutron dosemeters used in environments with high-energy neutrons.

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