Experiments will be conducted with the Bay Area Neutron Group at the 88 inch
Cyclotron at Lawrence Berkeley National Laboratory. First set of data will be
collected in gamma–gamma coincidence measurements of inelastic neutron scattering on iron 56. Scattering cross sections for this element are inadequately known
for transport calculations and although the level schemes of iron are well documented the accuracy of the cross section measurements needs to be improved by
10–15% in the relevant energy range of 0.5–20 MeV [1]. Reason for starting with
iron 56, besides the fact that it is the major component of stainless and Euro-fer
steels, is the fact that it has been singled out as a high priority isotope by the CIELO
collaboration.
Measurements will take place in Cave 0 of the 88 inch Cyclotron facility. Four
germanium detectors will be positioned roughly at an angle of 90° with respect to
the incident neutron beam. Coincident gammas will be measured in order to allow
the use of data for level scheme building. Once the data has been collected and
analyzed it will be compared with calculations. Different nuclear models allow
properties such as the reaction cross sections to be calculated. These calculations
are extremely complicated and cumbersome which is why computer codes have
been developed to perform them. State of the art code EMPIRE allows selection of
options and adjustment of input parameters such that the calculations best fit the
experimental conditions and allows loading of measured data for direct comparison
between evaluated data, measured data and theoretical predictions. Once the data
from upcoming experiments is analyzed the result will further be used in the
process of data evaluation to reduce the currently existing uncertainties in the
energy range of interest.
The same reaction code will later on be used for modeling the inelastic scattering
through various materials in MCF devices. Thickness of the target is not an input
parameter of EMPIRE however satisfactory results can be obtained by multiple runs
at different incident energies simulating the change in neutron energy spectrum.
Calculations will be weighted by the build up factor for materials of interest and
further supplemented by calculations taking into account the incident neutron flux.
If inelastic scattering turns out to be a significant mechanism in fusion reactor
environment full MCNP calculations will be necessary for precise modeling, these
calculations are out of the scope of this project.
3 Conclusions
Research outlined in previous sections has not yet been performed. Therefore no
definite conclusions or results can be presented at this point. However research
question that will be answered once the project is complete is how significant is the
mechanism of inelastic neutron scattering for neutron transport in fusion reactor
environment.
Effects of Inelastic Neutron Scattering in Magnetic …
231
Cyclotron at Lawrence Berkeley National Laboratory. First set of data will be
collected in gamma–gamma coincidence measurements of inelastic neutron scattering on iron 56. Scattering cross sections for this element are inadequately known
for transport calculations and although the level schemes of iron are well documented the accuracy of the cross section measurements needs to be improved by
10–15% in the relevant energy range of 0.5–20 MeV [1]. Reason for starting with
iron 56, besides the fact that it is the major component of stainless and Euro-fer
steels, is the fact that it has been singled out as a high priority isotope by the CIELO
collaboration.
Measurements will take place in Cave 0 of the 88 inch Cyclotron facility. Four
germanium detectors will be positioned roughly at an angle of 90° with respect to
the incident neutron beam. Coincident gammas will be measured in order to allow
the use of data for level scheme building. Once the data has been collected and
analyzed it will be compared with calculations. Different nuclear models allow
properties such as the reaction cross sections to be calculated. These calculations
are extremely complicated and cumbersome which is why computer codes have
been developed to perform them. State of the art code EMPIRE allows selection of
options and adjustment of input parameters such that the calculations best fit the
experimental conditions and allows loading of measured data for direct comparison
between evaluated data, measured data and theoretical predictions. Once the data
from upcoming experiments is analyzed the result will further be used in the
process of data evaluation to reduce the currently existing uncertainties in the
energy range of interest.
The same reaction code will later on be used for modeling the inelastic scattering
through various materials in MCF devices. Thickness of the target is not an input
parameter of EMPIRE however satisfactory results can be obtained by multiple runs
at different incident energies simulating the change in neutron energy spectrum.
Calculations will be weighted by the build up factor for materials of interest and
further supplemented by calculations taking into account the incident neutron flux.
If inelastic scattering turns out to be a significant mechanism in fusion reactor
environment full MCNP calculations will be necessary for precise modeling, these
calculations are out of the scope of this project.
3 Conclusions
Research outlined in previous sections has not yet been performed. Therefore no
definite conclusions or results can be presented at this point. However research
question that will be answered once the project is complete is how significant is the
mechanism of inelastic neutron scattering for neutron transport in fusion reactor
environment.
Effects of Inelastic Neutron Scattering in Magnetic …
231