Nuclear fission serves as the most fundamental physics phenomenon underlying nuclear energy. It is quite a complex process of large-amplitude collective motion of finite quantal systems, which produces a huge energy of around 200 MeV/fission, and fission neutrons, which are used to sustain chain reactions, and over 1,000 kinds of fission products are produced. Understanding nuclear fission is...
$^{239}$Puの熱中性子核反応における核分裂収率を核反応モデル計算コードCCONE~[1] を用いて計算した。実験データと比較して検証した結果を本発表で行う。
これまでの核データにおける核分裂収率の評価は、主に独立核分裂収率と積算核分裂収率を基にして評価値が決められてきた。しかし核分裂収率は、全運動エネルギー(TKE)や即発中性子、崩壊熱など様々な観測量と関連する物理量であり、それらも考慮した評価値の決定が求められている。JENDL-5~[2]...
The purpose of this research is to design new radionuclides suitable for brachytherapy sources. Brachytherapy is one of the radiotherapy technique which sealed radionuclides in capsules are inserted into the body. Photons, electrons from a sealed source are usually used. Dose rate can be controlled using a variety of irradiation setup, such as placement and irradiation time to the patients. In...
Experimental nuclear reaction data are essential for understanding nuclear reaction phenomena, developing nuclear theories and models, and evaluating data for nuclear data libraries. Efficient data mining from the Experimental Nuclear Reaction Database (EXFOR)[1] has a potential for utilization of modern computational analysis techniques to find trends, shortcomings, and hidden patterns in the...
We have developed the radiation dose evaluation system for indoor environments named 3D-ADRES-Indoor, which is especially designed for two applications: the estimation of radioactive source distributions with the machine learning technique and the planning of measures against estimated radioactive sources [1,2]. 3D-ADRES-Indoor mainly uses Particle and Heavy Ion Transport code System (PHITS)...
The cross sections of neutron-induced charged-particle emission reactions such as (n,p) and (n,$\alpha$) for many nuclides have not been measured as well as those of the neutron capture reaction. In the present work, new measurement technique for neutron-induced charged-particle emission reactions were developed. The new method uses plastic scintillator added with sample material for...
In fluoroscopy, radiation shielding effectively reduces radiation exposure to medical staff [1]. However, it is still unclear how to understand where the scattered radiation comes from and how to properly use radiation shields. The purpose of this study is to clearly visualize the direction of scattered radiation to assist in the optimal use of radiation shields.
The Monte Carlo code PHITS...
In the case of accidents involving inhalation of radioactive materials, there is a need for rapid evaluation of the amount of transuranium (TRU) nuclides such as Pu ingested in the body by measurement from outside of the body. In the measurement, L X-rays, which have energies of 10 to 30 keV and are emitted by internal conversion electrons due to $\alpha$-decay, are used. In order to measure...
In Boron Neutron Capture Therapy (BNCT) facilities, concrete of the treatment room is activated by neutrons and dose rate in the treatment room is still high after the end of neutron irradiation. The concrete wall surrounding the room is thick enough to reduce dose rate outside the room to a safety level. The concrete in certain area of the wall is highly radioactive. Estimating the amount of...
Photonuclear reaction cross-section data are essential for electron accelerator shielding design and possibly nuclear transmutation. So far, photonuclear cross-sections of various target materials have been evaluated up to a photon energy of 200 MeV within the nuclear data libraries, such as JENDL-5 [1]. Almost all data in JENDL-5 have been evaluated based on the experimental reaction...
Shield tunneling methods are widely used to construct large underground tunnels. Although the methods are considered safe, subsidence accidents due to underground cavities created during tunnel excavation have occurred in recent years. To prevent such accidents, it is necessary to detect the cavities and take some measures. Various exploration methods such as ground-penetrating radar have been...
Fission product yields (FPY) is one of the most important nuclear data, which provide information necessary for applications like burn-up calculation in nuclear reactors, environmental assessment of radioactive waste disposal and evaluation for production of valuable isotopes such as $^{99}$Mo for medical imaging. Traditionally, major nuclear data libraries (such as JENDL, ENDF, JEFF, etc.)...
Nuclear data on carbon ion induced reactions in a wide range of energy are needed for purposes such as improvement radiation protection for space exploration and evaluation systems for secondary exposure on radiation therapy. However, it is reported that there is no measurement data on double differential cross sections of incident high energy $^{12}$C particles between 100 MeV/u and 500...
Neutron source term is required for shielding design of accelerator facilities. A Time-of-Flight (TOF) technique is applied to get the source term. When TOF cannot be utilized at accelerator facilities (e.g., Continuous Wave (CW) operation), an unfolding method is useful. However, the validity of unfolding is not completely understood.
One of the accelerator facilities where CW operation...
In equation of state of nuclear matter, constraints on parameters of the symmetry energy $S(\rho)$ are important for understanding of the nuclear many-body system which is related to various astrophysical phenomena. The symmetry energy is essential for the neutron matter ($\delta\sim 1$ where $\delta$ is degree of asymmetry), but it is less certain than the symmetric nuclear matter...
Fast neutron measurements are indispensable technique in the field of experimental nuclear physics and nuclear data measurement. In order to discriminate gamma rays generated by the production of fast neutrons, it is necessary to use a detector capable of discriminating between gamma rays and fast neutrons. As a typical detector for fast neutrons, organic liquid scintillators are widely used....
A variety of unstable nuclear beams with atomic numbers (Z) up to 92 can be produced by the projectile fragmentation and in-flight fission from high intensity U beams at RIBF. Recently, it was found that $^{234−238}$Np can be created by a proton pickup reaction on 1 GeV/nucleon $^{238}$U beam. Owing to the recent developments of the high-Z beams at BigRIPS, energy dependence of the proton...
The control of occupational exposure in fluoroscopy and interventional radiology is critical due to the risk of radiation exposure. Current dosimetry measurements have limitations, such as incomplete whole-body measurements and lack of real-time measurements. To improve radiation awareness, we have developed a system that displays 2D scattered radiation distribution and estimates the...
We have measured a small-angle neutron and X-ray scattering (SANS and SAXS) of cement paste to investigate a nanoscale structure of cement paste [1, 2]. Through the in-situ SAXS measurements of cement paste, in particular, we have focused on a fine nanostructure that emerged with time as a shoulder on the SAXS profiles at the high-q region of around 3 nm$^{-1}$. Based on a microstructure model...
The Intranuclear Cascade model have been improved for calculation of alpha incident reaction. The fragmentation reaction which is dominant in alpha incident reactions is calculated using the model that incident alpha particle is broke up according to the probability, which show cluster state in the alpha particle, and density distribution of targets. In addition, the direct knockout reaction...
Neutron activation analysis is used in a variety of many fields, such as geology, medicine, and archaeology. In the neutron activation method, a sample is irradiated with neutrons and activated via neutron-induced reactions. The elemental composition is determined from the radioactivity of the sample. In measurement of radioactivities, -rays are often detected with a germanium detector which...
Purpose: At energies above the ($\gamma$,n) threshold, photons can interact with the nuclei of high-Z materials, liberating fast neutrons. The aim of this study was to validate the Monte Carlo simulation with the PHITS code for the TrueBeam LINAC using mono-energy. Additionally, we examined the photon neutron dose surrounding the TrueBeam LINAC's head and investigated the influence of field...
Accelerator neutrons generated by deuterons are new source for radioisotope (RI) production. In this system, neutrons are produced by the (d, n) reaction by deuteron irradiation on a thick neutron converter made of single element light nuclide such as C or Be. Generated neutrons irradiate the nuclides in a raw material turned into medical RI by direct reactions.
As a feature of the neutron...
