Thermal Neutron Capture Cross Sections of the PalladiumIsotopes

Conference · Mon Jul 17 04:00:00 EDT 2006

OSTI ID:925521

Firestone, R B; Krticka, M; McNabb, D P; Sleaford, B; Agvaanluvsan, U; Belgya, T; Revay, Zs

Precise gamma-ray thermal neutron capture cross sectionshave been measured at the Budapest Reactor for all elements withZ=1-83,92 except for He and Pm. These measurements and additional datafrom the literature been compiled to generate the Evaluated Gamma-rayActivation File (EGAF), which is disseminated by LBNL and the IAEA. Thesedata are nearly complete for most isotopes with Z<20 so the totalradiative thermal neutron capture cross sections can be determineddirectly from the decay scheme. For light isotopes agreement with therecommended values is generally satisfactory although large discrepanciesexist for 11B, 12,13C, 15N, 28,30Si, 34S, 37Cl, and 40,41K. Neutroncapture decay data for heavier isotopes are typically incomplete due tothe contribution of unresolved continuum transitions so only partialradiative thermal neutron capture cross sections can be determined. Thecontribution of the continuum to theneutron capture decay scheme arisesfrom a large number of unresolved levels and transitions and can becalculated by assuming that the fluctuations in level densities andtransition probabilities are statistical. We have calculated thecontinuum contribution to neutron capture decay for the palladiumisotopes with the Monte Carlo code DICEBOX. These calculations werenormalized to the experimental cross sections deexciting low excitationlevels to determine the total radiative thermal neutron capture crosssection. The resulting palladium cross sections values were determinedwith a precision comparable to the recommended values even when only onegamma-ray cross section was measured. The calculated and experimentallevel feedings could also be compared to determine spin and parityassignments for low-lying levels.

• Research Organization: Ernest Orlando Lawrence Berkeley NationalLaboratory, Berkeley, CA (US)
• Sponsoring Organization: USDOE Director. Office of Science. NuclearPhysics
• DOE Contract Number: AC02-05CH11231
• OSTI ID: 925521
• Report Number(s): LBNL--60966; BnR: KB0301042
• Country of Publication: United States
• Language: English

Related Subjects

07 ISOTOPE AND RADIATION SOURCES
38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEAR CHEMISTRY
73 NUCLEAR PHYSICS AND RADIATION PHYSICS
ACCURACY
CAPTURE
CROSS SECTIONS
DECAY
EXCITATION
FLUCTUATIONS
IAEA
NEUTRON REACTIONS
PALLADIUM
PALLADIUM ISOTOPES
PARITY
Palladium cross sections statistical model
SPECTROSCOPY
SPIN
THERMAL NEUTRONS