Recent results from GEANIE at LANSCER.O. Nelson1, N. Fotiades1, M. Devlin1, D. Dashdorj2, S. Cowell3, P. Talou3, T. Kawano3, G.E. Mitchell2 and J.A. Becker4
1 LANSCE-NS, LANL, Los Alamos, NM 87545, USA
2 North Carolina State University, Raleigh, NC 27695, USA
3 T-16, LANL, Los Alamos, NM 87545, USA
4 Lawrence Livermore National Laboratory, Livermore, CA 94550, USA
Published online: 21 May 2008
GEANIE, the Germanium Array for Neutron Induced Excitations, is an array of 26 high-resolution γ-ray and X-ray detectors at the WNR broad spectrum neutron source at LANSCE. The neutron source is driven by the pulsed 800 MeV proton beam of the LANSCE accelerator, enabling use of the time of flight technique to determine incident neutron energies. The time structure of the pulsed beam allows lifetime measurements during ~ 8 milliseconds between beam bursts. Reactions induced by neutrons in the energy range from 100 keV to over 200 MeV are measured. The γ-ray energy range covered is from 15 keV to 4 MeV. GEANIE has been in operation for over 10 years. Here we present an overview of recent results from GEANIE including neutron-induced γ-ray production cross sections, microsecond and millisecond isomer lifetimes, identification and quantification of possible neutron-induced γ-ray backgrounds in underground double beta decay measurements, and preequilibrium reaction studies. The observation of many new levels in 197Au, population of isomeric states in 190Ir, 197Au, and 202Tl, and cross sections for γ rays from 48Ti are presented. Measurement of neutron induced γ rays from Te, Pb, Cu and 76Ge that may contribute to backgrounds of underground neutrino-less double-beta decay experiments due to cosmic-ray induced neutrons are in progress.
© CEA 2008