Measurement of charged-particle emission double-differential cross section of fluorine for 14.2 MeV neutrons

Kondo, Keitaro; Murata, Isao*; Ochiai, Kentaro; Kubota, Naoyoshi*; Miyamaru, Hiroyuki*; Konno, Chikara; Nishitani, Takeo

Journal of Nuclear Science and Technology, 48(8), p.1146 - 1157, 2011/08

https://doi.org/10.3327/jnst.48.1146

We carried out a detailed measurement of the double-differential cross sections of fluorine for emitted protons, deuterons, tritons and -particles with 14.2 MeV neutron incidence. An improved charged-particle spectrometer with a pencil DT-neutron beam furnished at the FNS facility of Japan Atomic Energy Agency enabled us to obtain precise data with a fine energy resolution in wide energy range and angular range from 15 to 150 . The obtained data were compared with the nuclear data evaluated in JENDL-3.3 and ENDF/B-VII.0. As a result, large differences in the energy and angular distributions of emitted particles and the charged-particle production cross sections were found between the measured and evaluated data. Angular-differential cross sections for several discrete peaks corresponding to excited states of residual nuclei were extracted to discuss the reaction mechanism of charged-particle emission. The obtained data suggest that the charged-particle emission reaction of fluorine has a quite complicated mechanism where both the direct reaction process and the pre-equilibrium process contribute. The present experiment is the first simultaneous measurement of the four different kinds of charged particles and would provide useful data to confirm previous experimental data as well as to establish a nuclear reaction model of fluorine.

Angle-correlated spectrum measurement for two neutrons emitted from (n,2n) reaction with the coincidence detection technique using a pencil-beam DT neutron source

Murata, Isao*; Takagi, Satoshi*; Kondo, Keitaro; Shiken, Kimiaki*; Miyamaru, Hiroyuki*; Mitsuda, Motoyuki; Maekawa, Fujio; Ochiai, Kentaro; Nishitani, Takeo

Nuclear Instruments and Methods in Physics Research A, 595(2), p.439 - 446, 2008/10

https://doi.org/10.1016/j.nima.2008.07.039

A technique was developed to measure the angle-correlated neutron energy spectrum with the coincidence detection technique using a pencil-beam DT neutron source at the Fusion Neutronics Source (FNS) of the Japan Atomic Energy Agency (JAEA). Triple differential cross-sections of the Mn(n,2n) reaction were measured first, from which the total Mn(n,2n) reaction cross-section was deduced and compared with JENDL-3.3. The agreement was sufficient to prove the validity of the technique. With the present measuring technique, a complete measurement of a medium-heavy or heavy element such as manganese would become possible through several measurements, because the angle dependence of the emitted neutrons from it is normally weak. The technique will be a useful tool for measuring the angle-correlated neutron spectrum of light elements such as beryllium for investigation of their complicated nuclear reaction mechanism.

Measurement of the angle-correlated neutron spectrum for the Be(n,2n) reaction with a pencil-beam DT neutron source

Murata, Isao*; Takagi, Satoshi*; Shiken, Kimiaki*; Kondo, Keitaro; Miyamaru, Hiroyuki*; Ochiai, Kentaro; Nishitani, Takeo; Konno, Chikara

Proceedings of International Conference on Nuclear Data for Science and Technology (ND 2007), Vol.2, p.999 - 1002, 2008/05

The (n,2n) reaction plays a very important role in the design of fusion reactor. In the present study, using a pencil-beam DT neutron source, angle-correlated two neutrons emitted through (n,2n) reaction have directly been measured to determine (n,2n) reaction cross section with the coincidence detection technique for beryllium which is the most important element in the fusion reactor. In the experiment, two NE213 detectors were arranged very close to the sample to efficiently measure the two neutrons. The measured spectra were unfolded by FORIST with the detector response matrix evaluated by SCINFUL. As a relust, comparing with the evaluations of ENDF/B-VI and JENDL-3.3 for energies above 800 keV of the lower measurable limit energy, the shape of derived angula-differential cross-section fits JENDL-3.3 better than ENDF/B-VI. However, agreement of the cross section of (n,2n) above 800 keV was acceptable within 10 percents for both libraries.

Verification of nuclear data for DT neutron induced charged-particle emission reaction of light nuclei

Kondo, Keitaro; Murata, Isao*; Ochiai, Kentaro; Kubota, Naoyoshi; Miyamaru, Hiroyuki*; Takagi, Satoshi*; Shido, Shoichi*; Konno, Chikara; Nishitani, Takeo

Fusion Engineering and Design, 82(15-24), p.2786 - 2793, 2007/10

https://doi.org/10.1016/j.fusengdes.2007.03.013

no abstracts in English

Neutron elastic recoil detection for hydrogen isotope analysis in fusion materials

Kubota, Naoyoshi; Kondo, Keitaro; Ochiai, Kentaro; Nishitani, Takeo

Journal of Nuclear Materials, 367-370(2), p.1596 - 1600, 2007/08

https://doi.org/10.1016/j.jnucmat.2007.04.025

The Neutron Elastic Recoil Detection Analysis (NERDA) using a neutron beam was proposed to extend the analyzing depth of hydrogen isotopes up to several hundreds micrometers. The 14.1 MeV neutrons beam produced by the Fusion Neutronics Source facility in Japan Atomic Energy Agency entered a sample from the normal direction. Emitted particles from the sample were measured using a E-E counter telescope detector. Incident neutron fluence was monitored with a U fission chamber located behind the target chamber. The proof-of-principle experiment was performed using a standard sample of deuterated polyethylene film containing a known concentration of deuterium with the thickness of 100 m. The depth resolution was evaluated to be 99 m corresponding to 12% of the maximum probing depth of 801 m for the sample. For a carbon-based Plasma Facing Component (PFC) sample the depth resolution was expected to be 61 m, which was enough to reveal hydrogen isotope distributions of co-deposited layers. Also, we applied NERDA to analyses of hydrogen isotope distributions in PFCs of JT-60U.

Surface analysis for the TFTR Armor tile exposed to D-T plasmas using nuclear technique

Kubota, Naoyoshi; Ochiai, Kentaro; Kutsukake, Chuzo; Hayashi, Takao; Shu, Wataru; Kondo, Keitaro; Verzilov, Y.*; Sato, Satoshi; Yamauchi, Michinori; Nishi, Masataka; et al.

Proceedings of 21st IAEA Fusion Energy Conference (FEC 2006) (CD-ROM), 7 Pages, 2007/03

Fuel and impurity particles show complicated behavior on the surface of plasma facing components (PFC) in fusion devices. The study is important for the design of the fuel recycling, safety management of the tritium inventory, etc. Quantitative measurements of hydrogen and lithium isotopes together with other impurities on the PFC surface exposed to D-T plasmas in TFTR were performed using the deuteron-induced nuclear reaction analysis, imaging plate method, full combustion method and activation analysis. The tritium depth profile was different from deuterium one. The surface tritium largely contributed to the whole tritium in the sample. On the other hand, the retained amount of lithium-6 was lager than that of lithium-7. This relates to the injection of enriched lithium-6 pellets in some campaigns. No other impurities were detected. So the large amount of tritium remained near the surface and did not diffuse more deeply, which gives a bright prospect for tritium safety.

Application of rays from D(,)Li and F(,n)Na to alpha particle diagnostics

Ochiai, Kentaro; Kubota, Naoyoshi; Taniike, Akira*; Kitamura, Akira*; Kondo, Keitaro*; Nishitani, Takeo

Fusion Science and Technology, 51(2T), p.262 - 264, 2007/02

https://doi.org/10.13182/FST07-A1369

For the density of 3.5-MeV particle and the leakage particle in D-T plasmas, we propose the observation of 2.186-MeV -ray produced by D(,)Li reaction and the use of the activation method by F(,n)Na reaction, respectively. In order to verify these reaction rates, we have carried out the irradiation experiments by means of helium ion bombardment into a deuteride polyethylene and a calcium floride crystal samples. From our experiment, D(,)Li reaction rate is estimated to be 10msin the ITER typical plasma condition. So we obtained good prospect of the -ray measurement as the confined diagnostics by using high efficiency detector. Also, it was found that The number of leakage alpha particles in order of 10m could be estimated by the activation method with F(,n)Na.

Development of measurement technique for charged-particle emission double-differential cross section using pencil-beam neutron source (Cooperative research)

Kondo, Keitaro; Ochiai, Kentaro; Kubota, Naoyoshi; Nishitani, Takeo; Murata, Isao*; Miyamaru, Hiroyuki*; Takahashi, Akito*

JAEA-Research 2006-016, 50 Pages, 2006/03

JAEA-Research-2006-016.pdf:6.25MB

Charged-particle emission double- differential cross section (DDXc) is quite important to estimate nuclear heating, material damages of a fusion reactor. We have developed a new technique for detailed measurement of DDXc. The technique overcomes fundamental difficulties of DDXc measurement with a pencil-beam neutron source and a counter telescope consisting of silicon surface barrier detectors. A superior S/N ratio, fine energy and angular resolutions, a wide detection energy range, and an excellent particle discrimination are realized together with a reasonable measurement time. In order to confirm the validity of the spectrometer, measurements of the emitted -particle from Al(n,x) reaction and the recoiled proton from H(n,n) reaction are carried out. Based on the results, we conclude the validity and the superiority of the present spectrometry technique.

New approach to measure double-differential charged-particle emission cross sections of several materials for a fusion reactor

Kondo, Keitaro; Takagi, Satoshi*; Murata, Isao*; Miyamaru, Hiroyuki*; Takahashi, Akito*; Kubota, Naoyoshi; Ochiai, Kentaro; Nishitani, Takeo

Fusion Engineering and Design, 81(8-14), p.1527 - 1533, 2006/02

https://doi.org/10.1016/j.fusengdes.2005.08.070

In a fusion reactor development, double-differential charged-particle emission cross sections(DDXc) are necessary to estimate nuclear heating and material damages of candidate materials irradiated with neutrons. Especially in light nuclei such as Be, Li, and C, nuclear reactions are complicated and difficult to estimate energy spectra of emitted particles based only on theoretical calculations Therefore development of a new technique for precise measurements of DDXc is quite important. Recently we successfully developed a new spectrometer for measurement of DDXc using a pencil-beam DT neutron source of FNS in JAERI. In the present study we carried out measurements of DDXc of Be, C, F, and Al using the spectrometer. The present technique was valid from the result of measurement for the Al(n,x) reactions. Slight differences appeared between measured data and evaluation or previous experimental values for Be(n,x) reactions at backward scattering angle and in lower energy region.

Measurement of energetic charged particles produced in fusion materials with 14 MeV neutron irradiation

Ochiai, Kentaro; Kondo, Keitaro; Murata, Isao*; Miyamaru, Hiroyuki*; Kubota, Naoyoshi; Takahashi, Akito*; Nishitani, Takeo

Fusion Engineering and Design, 75-79, p.859 - 863, 2005/11

https://doi.org/10.1016/j.fusengdes.2005.06.116

The Fusion Neutronics Source (FNS) of JAERI currently carries out the measurements of energetic charged particles emitted from fusion materials irradiated with a well-collimated 14 MeV neutron beam. At the beginning, the double differential cross section beryllium was measured. We have measured proton, triton and a particle emitted from a beryllium sample of 100 m in thickness.The a particle and triton were produced by Be(n,)He, Be(n,2n)2 and Be(n,t)Li reactions respectively. Measured total reaction rates from the counts of a particles and tritons were 2.710 and 610/atom/neutron, respectively, which were consistent with the calculated values from the nuclear data JENDL-3.2.