Prompt neutron polarization asymmetries in photofission of Th232, U233,235,238, Np237, and Pu239,240
Abstract
Photofission experiments were performed on targets of Th232, U233,235,238, Np237, and Pu239,240 using nearly 100% linearly polarized, high intensity (∼5×106γ/s), and nearly-monoenergetic γ-ray beams having energies between 5.3 and 7.6 MeV at the High Intensity γ-ray Source (HIγS) located at Duke University and Triangle Universities Nuclear Laboratory. An array of 12-18 liquid scintillator detectors was used to measure prompt fission neutron yields parallel and perpendicular to the plane of beam polarization. Polarization asymmetries, the differences between the in-plane and out-of-plane yields divided by their sums, were measured. Asymmetries close to zero were found for 233,235U, Np237, and 239Pu while significant asymmetries (∼0.2-0.5) were found for Th232, 238U, and 240Pu. Predictions based on previously measured photofission fragment angular distributions combined with a model of prompt neutron emission agree well with the experimental results.
- Publication:
-
Physical Review C
- Pub Date:
- March 2014
- DOI:
- 10.1103/PhysRevC.89.034615
- Bibcode:
- 2014PhRvC..89c4615M
- Keywords:
-
- 25.85.Jg;
- 24.70.+s;
- 24.75.+i;
- 25.20.-x;
- Photofission;
- Polarization phenomena in reactions;
- General properties of fission;
- Photonuclear reactions