Search

We have measured the isomeric yield ratios of 197m,g Pt from the 198 Pt(γ,n) reaction and 190m2,g+m1 Ir from the nat Pt(γ,xn1p) reaction, induced with the bremsstrahlung end-point energies of 55-, 60-, and 65-MeV. The measurements were carried out by the activation method in combination with the direct γ-spectrometry. The experiments were performed at the 100 MeV electron linac of the Pohang Accelerator Laboratory (PAL). The obtained results at 55-, 60- and 65-MeV for the 197m,g Pt from the 198 Pt(γ,n) reaction are 0.166 ± 0.012, 0.174 ± 0.011, and 0.175 ± 0.011, whereas for the 190m2,g+m1 Ir from the nat Pt(γ,xn1p) reaction are 0.072 ± 0.006, 0.084 ± 0.006 and 0.087 ± 0.006, respectively. The present results are measured for the first time over the investigated energy range. The present data are compared with the similar literature data at lower energy to examine the role of excitation energy. [ABSTRACT FROM AUTHOR]

The Monte Carlo particle transport codes, FLUKA, PHITS, MCNPX, and MARS15 were benchmarked by comparison to the measured product yields of proton-induced reactions on 209Bi from 43 to 100 MeV energy range. Two rounds of experiment were carried out to measure product yields of 209Bi(p, xn)207,206,205,204,203Po and 209Bi(p, pxn)207,206,205,204Bi reactions by using 100 MeV and 69 MeV proton beams. The targets were arranged in the stacks consisting of 209Bi activation foils, Al and Au monitor foils, and Pb plates as energy degraders. The predictive capability of the codes has been proven to be satisfactory from 55 to 100 MeV energy range. However, all codes are likely to underestimate the product yields of both investigated reactions over whole energy range and also the discrepancy between codes and measurements become larger at energy lower than 55 MeV. [ABSTRACT FROM AUTHOR]

• The neutron yield and beam characteristics of 9Be(p, xn) reaction-based beam shaping assembly for neutron capture therapy were calculated by MCNP6, PHITS and GEANT4. • We report very interesting and important findings such that the neutron yield with a 10 MeV proton beam by MCNP6 was 7.7 times larger than values by the other codes but close to the experimental data. • In addition, the neutron spectrum calculated by MCNP6 was a bit harder (i.e., shift to the epithermal land fast region) than the spectra by the other codes. Neutron yields from 9Be(p,xn) reactions with a 2-cm thick beryllium target bombarded by proton beams of 5, 6, 7, 8, 9, and 10 MeV were investigated. Neutron beam characteristics through a pilot design of beam shaping assembly were calculated by using MCNP6, PHITS, and GEANT4. The neutron yield with a 10 MeV beam by MCNP6 was 7.7 times larger than values by the other codes, but close to the experimental data. The neutron spectrum and directionality were different among the codes. These differences could stem from different cross-section libraries and models used in the codes. The epithermal flux at the beam irradiation port by MCNP6 was 1.4 × 109 cm−2 s−1 for a proton current of 8 mA hitting the target. The ratio of thermal and epithermal flux was less than 0.01 and the forward directionality was 0.78. However, we suggest a new criterion regarding a ratio of fast and epithermal flux. [ABSTRACT FROM AUTHOR]

The flux-weighted average cross sections of natAg(γ,xn)103-106Ag reactions were measured with the bremsstrahlung end-point energy of 70 and 75 MeV using an activation and off-line γ-ray spectrometric technique. The GEANT4 code was used for the simulation of the bremsstrahlung spectra. The cross sections of natAg(γ,xn) 103-106Ag reactions as a function of mono-energetic photons were theoretically calculated by using the TALYS-1.96 code. The data of the present work and literature at different bremsstrahlung end-point energy are found to be in agreement with the theoretical values within the uncertainty limit. It can be seen that the flux-weighted average cross sections of the natAg(γ,xn)105.106Ag reactions increase with bremsstrahlung energy up to the Giant Dipole Resonance region. Thereafter, a small decrease trend with the bremsstrahlung energy was seen due to the opening of another reaction channel. [ABSTRACT FROM AUTHOR]

The isomeric yield ratios of 133m,g Ce and 137m,g Ce produced from the nat Ce(γ,xn) reactions were determined by using the activation and the off-line γ-ray spectrometric technique with the end-point bremsstrahlung energies of 55-, 60-, and 65-MeV at 100-MeV electron linac of the Pohang accelerator laboratory. The induced activities in the irradiated foils were measured by using an energy- and efficiency-calibrated HPGe detector coupled to a PC based multi-channel analyzer. The necessary corrections were made to improve the accuracy of the experimental results. The experimental results at bremsstrahlung energies of 55-, 60-, and 65-MeV were 0.324 ± 0.089, 0.331 ± 0.086, and 0.403 ± 0.089 for the 133m,g Ce, and 0.210 ± 0.062, 0.221 ± 0.061, and 0.262 ± 0.061 for the 137m,g Ce, respectively. The present results for nat Ce(γ,xn) 133m,g;137m,g Ce in this energy region were obtained for the first time which has no comparable literature data. The obtained isomeric yield ratios are compared with the calculated values based on the statistical model code TALYS 1.6. [ABSTRACT FROM AUTHOR]

We have determined the isomeric yield ratios for the isomeric pairs 106m,g Ag and 104m,g Ag produced on natural silver target nuclei in the bremstrahlung energy region from 40- to 60-MeV. The measurements were carried out by the activation method in combination with direct γ-spectrometry. The necessary corrections were made to improve the accuracy of the experimental results. The present yield ratios measured at 40, 45, 50, 55, and 60 MeV for the 106m,g Ag isomeric pair are 0.019 ± 0.002, 0.022 ± 0.002, 0.023 ± 0.002, 0.025 ± 0.002, and 0.025 ± 0.002, and those for the 104m,g Ag isomeric pair are 1.26 ± 0.12, 1.34 ± 0.12, 1.36 ± 0.12, 1.43 ± 0.12, and 1.49 ± 0.12, respectively. The obtained results are compared with those existing in literature and discussed. [ABSTRACT FROM AUTHOR]

Erratum to "Neutron yields of Be-9(p,xn)B-9 reactions and beam characterization for accelerator-based boron neutron capture therapy facility using MCNP6, PHITS, and Geant4 simulation results" [Nucl. Now, the neutron yield with a 10 MeV beam by MCNP6/ENDF/B-VIII was approximately 25 times larger than GEANT4/TENDL-2014. (2) The directionality of neutron beam at the beam exit port by GEANT4 was corrected. [Extracted from the article]