A two-dimensional energy and time-of-flight charged-particle spectrometer has been developed and used to measure the double-differential cross-section (DDX) data of (n, xp) and (n, xα) reactions for several elements with 14.1-MeV incident neutrons at OKTAVIAN, the Intense 14-MeV Neutron Source Facility of Osaka University. The DDX data of the 51V(n, xp), 51V(n, xα), natFe(n, xp), natFe(n, xα), 59Co(n, xp), 59Co(n, xα), natNi(n, xα), natCu(n, xα), 93Nb(n, xp), 93Nb(n, xα), and natMo(n, xp) reactions are measured. The angle-integrated energy differential cross-section (EDX) data were deduced from the measured DDX data and compared with other experimental results [except for the 59Co(n, xp) reaction] and evaluated nuclear data of JENDL fusion file (JENDL-FF). A comparison was also done with the ENDF/B-VI for the total reaction cross sections of all measured reactions except for the natMo(n, xp) reaction and the EDX of the natNi(n, xα) and natCu(n, xα) reactions. The theoretical calculations were done...

Recently, exploitation of cerebrospinal fluid (CSF) circulation has become increasingly recognized as a feasible strategy to solve the challenges involved in drug delivery for treating brain tumors. Boron neutron capture therapy (BNCT) also faces challenges associated with the development of an efficient delivery system for boron, especially to brain tumors. Our laboratory has been developing a system for boron delivery to brain cells using CSF, which we call the “boron CSF administration method”. In our previous study, we found that boron was efficiently delivered to the brain cells of normal rats in the form of small amounts of L-p-boronophenylalanine (BPA) using the CSF administration method. In the study described here, we carried out experiments with brain tumor model rats to demonstrate the usefulness of the CSF administration method for BNCT. We first investigated the boron concentration of the brain cells every 60 min after BPA administration into the lateral ventricle of normal rats. Second, we measured and compared the boron concentration in the melanoma model rats after administering boron via either the CSF administration method or the intravenous (IV) administration method, with estimation of the T/N ratio. Our results revealed that boron injected by the CSF administration method was excreted quickly from normal cells, resulting in a high T/N ratio compared to that of IV administration. In addition, the CSF administration method resulted in high boron accumulation in tumor cells. In conclusion, we found that using our developed CSF administration method results in more selective delivery of boron to the brain tumor compared with the IV administration method.

Time-resolved triton burnup studies have been carried out to estimate the behavior of alpha particles in DD fusion experimental devices. In those studies, 14 MeV neutrons emitted through DT reactions in DD plasmas should be measured selectively in the backgrounds of DD neutrons and gamma rays. For this purpose, a scintillating-fiber (Sci-Fi) based fast-neutron detector has been adapted because of its advantages such as fast response, design flexibility in detection efficiency by changing the number of Sci-Fi, and discrimination property against 2.4 MeV neutrons produced through DD reactions and gamma rays. However, its length had conventionally been set to around 10 cm without an optimization study of its design parameters to meet the requirements as 14 MeV neutron detector. In the present study, we tested three types of Sci-Fi detectors with three different lengths and compared with the simulated results of energy deposition, through which we tried to understand the phenomena in the detection process of fast neutrons. From the results, it has been shown that, due to the self-shielding of neutrons by Sci-Fi and the attenuation of scintillation photons during the transmission process to the photomultiplier tube, the optimal length of Sci-Fi is concluded to be about 6 cm.