Fumito Kitatani

Neutron-capture cross-sections of 244Cm and 246Cm measured with an array of large germanium detectors in the ANNRI at J-PARC/MLF

The neutron neutron-capture cross cross-sections of 244Cm and 246Cm were measured by the time-of-flight method in the energy range of 1–300 300 eV with an array of large germanium detectors in the Accurate Neutron-Nucleus Reaction measurement InstrumentANNRI at Material and Life Science Experimental Facility (MLF) of the Japan Proton Accelerator Research ComplexJ-PARC/MLF. The 244Cm resonances at around 7.7 and 16.8 8 eV and the 246Cm resonances at around 4.3 and 15.3 3 eV were observed in the capture reactions for the first time. The uncertainties of the obtained cross cross-sections are 5.8% at the top of the first resonance of 244Cm and 6.6% at that of 246Cm. The rResonance analyses were performed for low-energy ones using the code SAMMY. The prompt γ-ray spectra of 244Cm and 246Cm were also obtained. Eight and five new prompt γ-ray emissions were observed in the 244Cm(n, γ) and 246Cm(n, γ) reactions, respectively.

Cross-section measurement of 237Np (n, 𝛄) from 10 meV to 1 keV at Japan Proton Accelerator Research Complex

The cross-section of the 237Np reaction has been measured in the energy range from 10 meV to 1 keV using the ANNRI-NaI(Tl) spectrometer at the Japan Proton Accelerator Research Complex (J-PARC). The cross-section was obtained relative to that of the 10B reaction. The absolute value of the cross-section was deduced by normalizing the relative cross-section to the evaluated value of JENDL-4.0 at the first resonance. The thermal cross-section was obtained to be ( ) b. The Maxwellian-averaged cross-section for meV was derived as ( ) b by referring the cross-section below 10 meV from JENDL-4.0. These results lead to the Westcotts g-factor of .

Measurements of the 152Srn(γ,n) Cross Section with Laser-Compton Scattering γ Rays and the Photon Difference Method

The cross sections of the 152Sm(γ,n) and 197Au(γ,n) reactions have been measured with the laser-Compton scattering (LCS) γ beam in the 8.3–12.4MeV energy range. The photon difference method has been used for LCS γ rays in the data analysis for the first time. The present data for 197Au measured as the standard are in agreement with the preceding data and the recent recommendation. On the other hand, the preceding data for 152Sm at 8.3 MeV are twice as large as the present data.

Superdeformation in asymmetric N>Z nucleus 40Ar

Abstract A rotational band with five γ -ray transitions ranging from 2 + to 12 + states was identified in 40 Ar. This band is linked through γ transitions from the excited 2 + , 4 + and 6 + levels to the low-lying states; this determines the excitation energy and the spin–parity of the band. The deduced transition quadrupole moment of 1.45 − 0.31 + 0.49 ± 0.15 eb indicates that the band has a superdeformed shape. The nature of the band is revealed by cranked Hartree–Fock–Bogoliubov calculations and a multiparticle–multihole configuration is assigned to the band.

Measurement of the 80Se(γ, n) Cross Section Using Laser-Compton Scattering γ-Rays

The 80Se(γ, n)79Se cross section was measured with laser-Compton scattering (LCS) γ-rays to supply fundamental data for the estimation of the inverse reaction cross sections, i.e., the 79Se(n, γ)80Se cross section. An enriched 80Se sample and a reference 197Au sample were irradiated with LCS γ-rays whose maximum energy was varied from 10.5 to 16.0 MeV. The energy distributions of LCS γ-rays were precisely determined using a high-resolution high-energy photon spectrometer (HHS). Emitted neutrons were detected by a high-efficiency 4π-3He detector. The excitation function of the 80Se(γ, n) cross section was determined for the energy range of 10.2–14.6 MeV. The energy point corresponding to each cross section was deduced using the accurately determined energy distribution of LCS γ-rays.

Synergistic effect of combining two nondestructive analytical methods for multielemental analysis.

We developed a new analytical technique that combines prompt gamma-ray analysis (PGA) and time-of-flight elemental analysis (TOF) by using an intense pulsed neutron beam at the Japan Proton Accelerator Research Complex. It allows us to obtain the results from both methods at the same time. Moreover, it can be used to quantify elemental concentrations in the sample, to which neither of these methods can be applied independently, if a new analytical spectrum (TOF-PGA) is used. To assess the effectiveness of the developed method, a mixed sample of Ag, Au, Cd, Co, and Ta, and the Gibeon meteorite were analyzed. The analytical capabilities were compared based on the gamma-ray peak selectivity and signal-to-noise ratios. TOF-PGA method showed high merits, although the capability may differ based on the target and coexisting elements.

Measurement of 76Se and 78Se (γ, n) Cross Sections

The (γ, n) cross sections of Se isotopes (76Se,78Se) were measured to supply fundamental data for estimating the inverse reaction cross section, i.e., the 79Se(n, γ)80Se cross section. The enriched samples and a reference 197Au sample were irradiated with laser-Compton scattering (LCS) γ-rays. The excitation function of each (γ, n) cross section was determined for the energy range from each near neutron separation energy to the threshold energy of (γ, 2n) reaction. The energy point corresponding to each cross section was deduced using the accurately determined energy distribution of LCS γ-rays. Systematic (γ, n) cross sections for Se isotopes including 80Se were compared with those calculated by using a statistical model calculation code TALYS.

Performance of the LaBr 3 (Ce) scintillator for nuclear resonance fluorescence experiment

Performance of the LaBr3(Ce) scintillator for nuclear resonance fluorescence (NRF) experiment was investigated. Linearity and energy resolutions of the LaBr3(Ce) scintillator of 3 inch in diameter × 3 inch in thickness were measured using NRF scattering gamma ray from 208Pb (5.5 MeV and 7.3 MeV) and 24Mg (10.7 MeV). The linearity of the output for the gamma ray energy was less than 1 % and the energy resolution of the scintillator in keV was almost proportional to the square root of the gamma ray energy up to 10.7 MeV.

Photoneutron Cross Sections for Au Revisited: Measurements with Laser Compton Scattering γ-Rays and Data Reduction by a Least-Squares Method

Photoneutron cross section measurements were made for Au in the entire energy range of the (γ,n) channel based on a direct neutron counting with quasi-monochromatic γ-rays produced in inverse Compton scattering of laser photons with relativistic electrons. The data were analyzed by a least-squares method to deduce photoneutron cross sections. The analysis significantly reduced experimental uncertainties compared with those resulting from the photon difference method. The result is compared with the previous data by direct neutron counting with γ-rays produced in positron annihilation in flight and by photoactivation with bremsstrahlung. The present data are in good agreement with the previous data near the neutron threshold, while there remain some discrepancies between the present and the previous data above 10 MeV.

Two-Dimensional Isotope Imaging of Radiation Shielded Materials Using Nuclear Resonance Fluorescence

A novel method for two-dimensional (2D) imaging of a specific isotope in a material, which is hidden by a thick radiation shield is presented. Nuclear resonance fluorescence and the laser Compton scattering are used in the present method. We measured γ-rays of 5512 keV from the nuclear resonance fluorescence of 208Pb at several points, and obtained a 2D image of isotope distribution.