A high precision n-p scattering measurement at 14.9 MeV

The n-p scattering angular distribution was measured with 14.9 MeV incident neutrons using the traditional time-of-flight technique with neutron-gamma discrimination. The scattering angle varied from 20o to 65o (laboratory system) in 5o incremental steps. The efficiency of the neutron detectors was measured in the energy range 2–9 MeV relative to the 252Cf-standard, and was calculated using Monte Carlo methods in the 2–14 MeV energy range. Two methods of analysis were applied for experimental and simulated data: a traditional approach with a fixed threshold, and a dynamic threshold approach. The present data agree with the ENDF/B-VII evaluation for the shape of n-p angular distribution within about 1.5%

Collective Quadrupole Behavior in \u3csup\u3e106\u3c/sup\u3ePd

Excited states in 106Pd were studied with the (n,n′γ) reaction, and comprehensive information for excitations with spin ≤6ℏ was obtained. The data include level lifetimes in the femtosecond regime, spins and parities, transition multipolarities, and multipole mixing ratios, which allow the determination of reduced transition probabilities. The E2 decay strength to the low-lying states is mapped up to ≈2.4 MeV in excitation energy. The structures associated with quadrupole collectivity are elucidated and organized into bands

MEASUREMENTS OF THE H(N,N) ANGULAR DISTRIBUTION OF 10MEV NEUTRON ENERGY.

Relative measurements of the cross section for scattering of neutrons by protons have been made at 10 MeV neutron energy for center-of-mass neutron scattering angles from 60' to 180'. The measurements were made using the Ohio University Accelerator Laboratory's tandem Van de Graaff accelerator with the D(d,n) reaction as the neutron source. The data are in good agreement with predictions from the phase shift analyses of Arndt, the groups of Nijmegen and Bonn, and the ENDF/B-V evaluation. The ENDF/B-VI evaluation does not appear to have the same angular dependence as the data. KEYWORDS: hydrogen cross section, neutron cross section standard, hydrogen angular distribution standar

Accelerated radiation damage test facility using a 5 MV tandem ion accelerator

We have developed a new irradiation facility that allows to perform accelerated damage tests of nuclear reactor materials at temperatures up to 400�C using the intense proton (<100 μA) and heavy ion (≈10 μA) beams produced by a 5 MV tandem ion accelerator. The dedicated beam line for radiation damage studies comprises: (1) beam diagnosis and focusing optical components, (2) a scanning and slit system that allows uniform irradiation of a sample area of 0.5-6 cm 2 , and (3) a sample stage designed to be able to monitor in-situ the sample temperature, current deposited on the sample, and the gamma spectrum of potential radio-active nuclides produced during the sample irradiation. The beam line capabilities have been tested by irradiating a 20Cr-25Ni-Nb stabilised stainless steel with a 3 MeV proton beam to a dose level of 3 dpa. The irradiation temperature was 356�C, with a maximum range in temperature values of �6�C within the first 24 h of continuous irradiation. The sample stage is connected to ground through an electrometer to measure accurately the charge deposited on the sample. The charge can be integrated in hardware during irradiation, and this methodology removes uncertainties due to fluctuations in beam current. The measured gamma spectrum allowed the identification of the main radioactive nuclides produced during the proton bombardment from the lifetimes and gamma emissions. This dedicated radiation damage beam line is hosted by the Dalton Cumbrian Facility of the University of Manchester

Collective and two-quasiparticle excitations in Te-128

Excited levels of Te-128 to 3.3 in MeV excitation have been studied using gamma-ray spectroscopy following inelastic scattering of accelerator-produced neutrons. Spectroscopic information, including transition energies, level spins, E2/M1 multipole-mixing ratios, and gamma-ray branching ratios, was determined from gamma-ray excitation functions measured from E-n = 2.15-3.33 MeV in 90-keV increments, gamma-ray angular distributions measured at E-n = 2.2, 2.8, and 3.3 MeV, and gamma gamma coincidences measured at E-n = 3.6 MeV. Lifetimes of levels in Te-128 were deduced using Doppler-shift attenuation techniques. Absolute transition probabilities were determined for many levels and compared to interacting boson model and particle-core coupling model calculations to identify few particle and collective structures; states exhibiting the decay characteristics expected for two-phonon, mixed-symmetry, and quadrupole-octupole coupled states are identified

A high precision n-p scattering measurement at 14.9 MeV

The n-p scattering angular distribution was measured with 14.9 MeV incident neutrons using the traditional time-of-flight technique with neutron-gamma discrimination. The scattering angle varied from 20o to 65o (laboratory system) in 5o incremental steps. The efficiency of the neutron detectors was measured in the energy range 2–9 MeV relative to the 252Cf-standard, and was calculated using Monte Carlo methods in the 2–14 MeV energy range. Two methods of analysis were applied for experimental and simulated data: a traditional approach with a fixed threshold, and a dynamic threshold approach. The present data agree with the ENDF/B-VII evaluation for the shape of n-p angular distribution within about 1.5%

A new measurement of the H(n,n)H elastic scattering angular distribution at 14.9 MeV

The relative angular distribution of the scattering of neutrons by protons was measured at En = 14.9 MeV neutron energy for center-of-mass scattering angles ranging from 60° to 180°. Absolute angular distribution values were obtained by normalizing the measured line shape to the accurately known n-p total cross section. Initial assessment indicates a somewhat better agreement of the data with the predictions of Arndt and Nijmegen than with the ENDF/B-VII.0 evaluation