Double Differential Neutron Emission Cross Research Articles

Measurements of Double Differential Cross Sections at OKTAVIAN

This is a brief review of the measurements of double differential neutron emission cross sections, which have been done at the OKTAVIAN facility of Osaka University since 1981, for many elements of fusion reactor materials. In the phase-1 experiments, double differential cross sections with high energy resolution and good counting satisfies were accumulated for D, Li, Be, B, C, N, O, F, Na, Al, Si, CI, Ti, Cr, Mn, Fe, Ni, Cu, Zr, Nb, Mo, W and Pb. The ring geometry TOF spectrometer was used in the phase-1, a drawback of which was due to the considerable variation of incident energy. In the phase-2 experiments, a new TOF spectrometer was installed for fixing the incident neutron energy to be 14.1 MeV and keeping the energy resolution and counting statistics. We can then obtain angle-integrated emission spectra and partial differential cross sections from measured double differential neutron emission cross sections. In the phase-2, measurements have been done for Be, C, 10B, 11B, F, Mg, Al, Si, V, Cr, Fe, Ni, Cu, Pb and Bi. All the data in the two phases have been efficiently utilized to improve evaluated neutron cross sections in JENDL-3, EFF-l and ENDF/B-VI.

Measurements of double differential cross sections at OKTAVIAN.

This is a brief review of the measurements of double differential neutron emission cross sections, which have been done at the OKTAVIAN facility of Osaka University since 1981, for many elements of fusion reactor materials. In the phase-1 experiments, double differential cross sections with high energy resolution and good counting satisfies were accumulated for D, Li, Be, B, C, N, O, F, Na, Al, Si, CI, Ti, Cr, Mn, Fe, Ni, Cu, Zr, Nb, Mo, W and Pb. The ring geometry TOF spectrometer was used in the phase-1, a drawback of which was due to the considerable variation of incident energy. In the phase-2 experiments, a new TOF spectrometer was installed for fixing the incident neutron energy to be 14.1 MeV and keeping the energy resolution and counting statistics. We can then obtain angle-integrated emission spectra and partial differential cross sections from measured double differential neutron emission cross sections. In the phase-2, measurements have been done for Be, C, 10B, 11B, F, Mg, Al, Si, V, Cr, Fe, N...

Measurement of Double Differential Neutron Emission Cross Sections for Incident Neutrons of 14 MeV

To provide accurate double differential neutron emission cross sections of fusion reactor candidate elements at En = 14 MeV, a fixed 8.3 m TOF facility with an NE213 detector of 25.4 cm diameter was installed in the 85° direction of a pulsed D-T source. Detail of scattering experiment using this facility is described. Energy resolution is ± 0.21 MeV at 14 MeV and good counting statistics is attained by about 1/h run using a cylindrical sample of 3 cm in diameter and 7 cm long. Measurements of double differential neutron emission cross sections are carried out for C, F, Mg, Al, Si, V, Cu and Pb. Results are compared with evaluated neutron emission data. Energy resolution is sufficient enough to deduce partial angular differential cross sections for elastic and discrete inelastic scatterings.

Measurement of double differential neutron emission cross sections for incident neutrons of 14MeV.

Measurement of double differential neutron emission cross sections for incident neutrons of 14MeV.

Double-Differential Neutron-Emission Cross Sections for7Li and Incident Neutrons between 1.6 and 13.8 MeV

Double-differential neutron-emission cross sections for the /sup 7/Li(n,xn) reaction are presented for average emission angles of 24, 40, 60, 90, 120, and 150 deg. The incident neutron energy covers the range from 1.6 to 13.8 MeV. The cross sections were measured using an electron linear accelerator as a pulsed white neutron source. Elastically scattered neutrons and neutrons scattered via the 0.48-MeV state are treated as one single group. Inelastic scattering cross sections are obtained for the 4.63- and 6.54-MeV states. For this purpose, the underlying neutron continuum coming from competing tritium-producing reactions (three-particle breakup and sequential two-step reaction via the /sup 5/He ground state) is estimated using simple physical model calculations. The data are compared with recent evaluations.

A spectrometer for double-differential neutron-emission cross section measurements in the energy range 1.6 to 16 MeV

A neutron spectrometer for the measurement of double-differential neutron-emission cross sections has been set up. An electron linac (GELINA) is used as a pulsed white neutron source. The energy of the incident neutrons is determined by the time-of-flight method. The secondary neutron spectra are determined by unfolding the pulse-height distributions observed in eight NE213-scintillators surrounding the sample. The measured spectra are normalised to the shape of the incident neutron flux measured with a 235U-fission chamber, and afterwards converted to absolute cross sections using as standard the carbon differential elastic scattering cross section below 2 MeV.

Neutron emission cross section measurements with a 14 MeV neutron generator

The PINSTECH 14 MeV Neutron Generator Facility has been used for the measurements of double differential neutron emission cross sections of Al, Cu and Pb in the emitted neutron energy range of 3–14 MeV and in the 30°–130° range. Integrated neutron emission cross sections are given and compared with previously reported values.

Interaction of fast neutrons with6,7LI

Abstract Energy-angle double differential neutron emission cross sections (DDX) of lithium isotopes have been measured at incident neutron energies of 4.2 ∼ 6.0 and 14.2 MeV by the time-of-flight method. The 6,7Li (n,2n) reaction cross sections were deduced. A coupled-channel analysis was also made very successfully of the differential elastic and inelastic scattering cross sections measured at 9 ∼ 14 MeV at TUNL. This work was performed for preparation of JENDL-3PR2.

Double differential neutron emission cross sections of10B AND11B at 6, 10 and 14 MeV and of6Li,7Li and12C at 14 MeV

Abstract Neutron emission spectra of 10B and 11B were measured at 6, 10 and 14.1 MeV and those of 6Li, 7Li. and carbon at 14.1 MeV using time-of-flight techniques. Absolute double differential cross sections were obtained by using scattering from hydrogen as a cross section reference. Integration over energy ranges and solid angle yielded integrated elastic and total neutron emission cross sections. At 6 and 10 MeV excellent agreement with total cross section data is found; at 14.1 MeV the new data tend to be higher than expected. The biggest error source in the continuous spectra stems from uncertainties in the input library (ENDF/B-V) of the Monte Carlo correction for multiple scattering. In particular, the library for 11B appears to be very unrealistic, with a total elastic cross section at 14.1 MeV which should be higher by 50%.

Double-differential neutron-emission cross section for the 7Li (n, Xn) reaction between 1.6–16 MeV

Abstract A neutron spectrometer for the measurement of double-differential neutron-emission cross sections has besn set up. The electron linac GELINA was used as a pulsed white neutron source. The energy of the incident neutrons was determined by the time-of-flight method with a source to sample distance of 60 m. The secondary neutron spectra were determined by unfolding the pulse height distributions as observed in six NE213-scintillators located at 20 cm from the sample. Here we present preliminary results for the 7Li (n,Xn) reaction obtained with a thin sample (0.0325 at/b) for emission angles Θ = 24, 60, 90, 120, 150, 160 degree and for incident neutron energies between 1.6 and 16 MeV. The data have been normalised to the shape of the incident neutron-flux as determined with an 235U fission chamber. The absolute values are based on the differential elastic cross section of 12C below 2 MeV.

Double-Differential Neutron Emission Cross Sections of6Li and7Li at Incident Neutron Energies of 4.2, 5.4, 6.0 and 14.2 MeV

Energy-angle double-differential neutron emission cross sections of lithium isotopes were measured at incident neutron energies of 4.2, 5.4 and 14.2 MeV for 6Li and of 5.4, 6.0 and 14.2 MeV for 7Li using a time-of-flight spectrometer. Care was taken in background subtraction and in data correction for sample-size effects. Detailed comparison of the present results was made with the evaluated data in JENDL-3PR1. A spectrum fitting method was used to extract the 6,7Li(n, n'x)α and (n, 2n) reaction cross sections. Neutrons emitted from the (n, 2n) reactions were well described by the conventional evaporation model. A simple calculation with a final-state Coulomb interaction was effectively applied for the 6,7Li(n, n'x)α reactions. Angle-integrated cross sections of the 7Li(n, n't)α reaction were in good agreement with the JENDL-3PR1 data except the data measured at 6.0MeV. The angular distributions of elastically and inelastically scattered neutrons were successfully analyzed with the coupled-channel method at the incident neutron energy of 14.2 MeV.

Double-differential neutron emission cross sections of 6Li and 7Li at incident neutron energies of 4.2, 5.4, 6.0 and 14.2 MeV.

Energy-angle double-differential neutron emission cross sections of lithium isotopes were measured at incident neutron energies of 4.2, 5.4 and 14.2 MeV for 6Li and of 5.4, 6.0 and 14.2 MeV for 7Li using a time-of-flight spectrometer. Care was taken in background subtraction and in data correction for sample-size effects. Detailed comparison of the present results was made with the evaluated data in JENDL-3PR1. A spectrum fitting method was used to extract the 6,7Li(n, n'x)α and (n, 2n) reaction cross sections. Neutrons emitted from the (n, 2n) reactions were well described by the conventional evaporation model. A simple calculation with a final-state Coulomb interaction was effectively applied for the 6,7Li(n, n'x)α reactions. Angle-integrated cross sections of the 7Li(n, n't)α reaction were in good agreement with the JENDL-3PR1 data except the data measured at 6.0MeV. The angular distributions of elastically and inelastically scattered neutrons were successfully analyzed with the coupled-channel method ...

Measurements of Double Differential Neutron Emission Cross Sections for Fusion Reactor Candidate Elements

Measurements of Double Differential Neutron Emission Cross Sections for Fusion Reactor Candidate Elements

Measurements of double differential neutron emission cross sections for fusion reactor candidate elements.

Double differential neutron emission cross sections (DDX) are useful for the fusion neuronics calculations. Using the intense 14 MeV neutron source facility OKTAVIAN, an experimental system has been established to measure DDX of candidate material elements for fusion reactor. Energy spectra of secondary neutrons from ring scattering samples are measured with high accuracy by means of the time-of-flight technique. The DDX data for D, O, Si, F, Ti, Mn and Bi are shown in the energy range of 14–0.3 MeV of secondary neutrons and the data for Li, Be, Pb and Bi are given in the range of 14 MeV–50 keV. Measured data are mainly compared with the calculations based on ENDF/B-IV.