Measurements of neutron photoproduction cross sections for {sup 232}Th and {sup 238}U using capture gamma rays

Journal Article · Sat May 01 04:00:00 EDT 1999 · Nuclear Science and Engineering

OSTI ID:343640

Goncalez, O L; Geraldo, L P; Semmler, R ^[1]

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1. Inst. de Pesquisas Energeticas e Nucleares, Pinheiros, Sao Paulo (Brazil). Div. de Fisica Nuclear

Neutron photoproduction studies for {sup 232}Th and {sup 238}U were carried out from 5.61 to 10.83 MeV, by using up to 30 neutron capture gamma rays with high resolution in energy (4 to 20 eV), produced in an experimental arrangement at the IPEN-IEA-R12-MW research reactor. Samples of U{sub 3}O{sub 8} depleted to 0.34% in {sup 235}U and natural ThO{sub 2} were irradiated inside a 4{pi} sr long-counter neutron detector system, 520.5 cm away from the capture target. The gamma-ray flux was determined by means of a coaxial solid state Ge(Li) detector (EG and G ORTEC, 25 cm{sup 3}, 5%) previously calibrated with capture gamma rays from a standard target of nitrogen (melamine). The compound neutron photoproduction cross section was measured for the gamma-ray spectrum produced by each capture target. Two methods to unfold the set of experimental data were proposed in order to obtain the differential cross sections at the main gamma line energies: the iterative and the least-squares methods. The calculated neutron photoproduction cross sections for {sup 232}Th and {sup 238}U were compared with experimental data reported by other authors who have employed different gamma-ray sources. A good overall agreement was observed among the experimental data, however, marked discrepancies were identified for some data points, indicating the possibility of narrow structures showing up at these excitation energies.

• OSTI ID: 343640
• Journal Information: Nuclear Science and Engineering, Journal Name: Nuclear Science and Engineering Journal Issue: 1 Vol. 132; ISSN NSENAO; ISSN 0029-5639
• Country of Publication: United States
• Language: English

Related Subjects

66 PHYSICS
DIFFERENTIAL CROSS SECTIONS
ITERATIVE METHODS
LEAST SQUARE FIT
PHOTONUCLEAR REACTIONS
THORIUM 232 TARGET
URANIUM 238 TARGET