• Journal of Radiation Protection and Research
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• v.38 no.3
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• pp.143-148
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• 2013

Operational nuclear facilities such as nuclear power plants and particle accelerators show various neutron spectra according to the type of facilities and specific position. Necessities of neutron dose management and neutron monitoring for radiation protection of radiation workers in such a kind of facilities have continuously increased in recent years. Bonner sphere spectrometers are widely used for measurement of neutron spectra. Data on response function of neutron detector, default neutron spectra and count rates of Bonner sphere spectrometer are required to obtain unfolded neutron spectra in specific workplaces. In this study, we carried out measurement of neutron spectra produced in MC50 cyclotron using Bonner sphere spectrometer with LiI scintillation detector. Additionally, we estimated quantitative data on neutron flux, mean neutron energy and ambient dose equivalent rate according to the incident proton energies and positions in MC50 cyclotron.

• Nuclear Engineering and Technology
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• v.54 no.3
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• pp.1024-1029
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• 2022

Composite scintillation screens on a base of Gd_1.2Y_1.8Ga_2.5Al_2.5O₁₂:Ce (GYAGG) scintillator have been evaluated for neutron detection. Besides the powdered scintillator, the composite includes ⁶LiF particles; both are merged with a binder and deposited onto the light-reflecting aluminum substrate. Results obtained demonstrates that screens are suitable for use with a silicon photomultiplier readout to create a prospective solution for a compact and low-cost thermal neutron sensor. Composite GYAGG/⁶LiF scintillation screen shows a pretty matched sensitivity and γ-background rejection with a widely used ZnS/⁶LiF screens however, possesses forty times faster response.

• Nuclear Engineering and Technology
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• v.4 no.2
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• pp.116-131
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• 1972

A fast neutron time-of-flight spectrometer has been constructed with suitable choice of target thickness and proton bombarding energy in Li$^{7}$ (p, n) Be$^{7}$ nuclear reaction for a continuous keV spectrum of neutrons at 0 degree in 1-nsec pulse from a Van do Graaff and a time-pick-up fast neutron detector assembled with a 5 mm-thick 92% enriched B$^{10}$ slab and four heavily shielded 4＂$\times$3＂ NaI scintillation detectors. Energy resolution of this spectrometer is better than 0.3% at 50 keV and the signal-to-background ratio is also improved. Total cross section measurements of several separated single isotopes have been carried out with this spectrometer and analyzed by Rmaxtrix multi-level computer code. The spin values and resonance parameters of each individual resonances are given.

• Journal of the Korean Society of Radiology
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• v.1 no.1
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• pp.45-49
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• 2007

keV-neutron capture gamma-ray spectrum of $^{197}Au$(natural gold) sample have been measured in neutron energy range from 10 to 90 keV using the 3-MV pelletron accelerator of the Research Laboratory for Nuclear Reactors at the Tokyo Institute of Technology. Pulsed keV neutrons were produced from the $^7Li(p,n)^7Be$ reaction by bombarding on the $^7Li$ target with the 1.5-ns bunched proton beam. The incident neutron spectrum on the Au sample was measured by a $^6Li$-glass scintillation detector and TOF method. Capture gamma-rays from Au sample were measured by anti-Compton NaI(TI) spectrometer. Five average neutron energy regions were selected to obtain the neutron capture spectrum. Several gamma-ray peaks in the spectrum were found in the present experiment.

• Journal of Radiation Protection and Research
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• v.13 no.2
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• pp.9-20
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• 1988

In order to quantify the contribution of cosmic-ray ionizing component to the dose given by natural background radiation, a series of measurement has been carried out using LiF TLDs for about one and a half years on quarterly basis. Three different types of LiF TLDs namely, chips and PTFE based disks of $^{7}LiF$, and the same disks of $^{6}LiF$ for identifying possible contribution of neutron component were used. Measurements were made by placing badge-incased TLDs in a lead castle of 10 to 15cm thick installed in a room on the third floor of a four-story building in CNU Daedeok campus for 5 cycles of 90 days. For comparison a series of spectrometric study was also performed for the energy region over 3MeV using a 3'${\phi}\;{\times}\;3$'NaI(Tl) scintillation detector in association with an MCA of 1024 channels, and it was found that the data obtained by the TLDs placed in the lead castle indicate 75% of the dose given by outdoor cosmic-ray component. The results obtained by the TLDs through correction for shielding loss show that the outdoor dose contribution of ionizing component of cosmic rays at this campus is $34.3{\pm}1.1nGy/h$ which satisfactorily agrees with that expected for our particular location of measurement.

• Nuclear Engineering and Technology
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• v.54 no.7
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• pp.2564-2571
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• 2022

SiPMs are generally coupled into whole columns in gamma energy spectrum measurement, but the relationship between the distribution of whole SiPM columns and the energy resolution of the measured energy spectra is rarely reported. In this work, ∅ 3 × 3 inch NaI scintillator is placed on an 8 × 8 SiPM array, and the energy resolution of the ¹³⁷Cs peak at 662 keV corresponding to the γ-ray is selected as a reference. Each SiPM is switched to explore the influence of the number of SiPM arrays, distribution position, and reflective layer on the energy resolution of SiPMs. Results show that without coupling, the energy resolution is greatly improved when the number of SiPMs ranges from 4 to 32. However, after 32 slices (the area covered by SiPMs relative to the scintillator reaches 25.9%), the improvement in energy resolution and total pulse count is not obvious. In addition, the position of SiPMs relative to the scintillator does not exert much impact on the energy resolution. Results also indicate that by adding a reflective film (ESR), the energy resolution of the tested group increases by 10.38% on average. This work can provide a reference for the design and application of miniaturized SiPM gamma spectrometers.