Program - Brookhaven National Laboratory

simulated response based on existing nuclear data shows a large excess of high-energy gamma radiation
[Fijalkowska2012, Karny2013] in most cases. The presentation will include quoted references to original
publications.
*This work supported by the U.S. Department of Energy Office of Nuclear Physics.
[1] J.R. Beene et al., J. Phys. G: Nucl. Part. Phys. 38, 024002, (2011) and references therein.
HD 2 4:00 PM
New Half-Life Measurements for Millisecond Isomers at LANSCE
M. Devlin, R.O. Nelson, N. Fotiades, J.M. O’Donnell
LANSCE, Los Alamos National Laboratory, Los Alamos, NM 87545 USA
The unique time structure of the pulsed neutron beam at the Weapons Neutron Facility (WNR) at the Los
Alamos Neutron Science Center (LANSCE) allows for lifetime measurements of isomeric states populated
in neutron-induced reactions, for isomers in the range from tens of microseconds to tens of milliseconds.
This feature has been used in the past for half-life measurements of isomers in Tl nuclei [1,2], using the
GEANIE array of HPGe detectors to identify their decay between the pulses of neutrons from WNR. We
report here on a set of new half-life measurements for various isomeric states in the millisecond range,
again using the GEANIE array: 114m In, 205m Pb, 75m As, 71m Ge, 171m Yb, 208m Bi, and 206m Bi, as well as
others. For some of these measurements, the repetition rate of the LANSCE accelerator was modified, in
order to better measure longer half-lives. The new measurements will be presented and compared to prior
measurements, with attention to the systematic errors involved in these measurements.
[1] N Fotiades, RO Nelson, M Devlin, and JA Becker, Phys Rev C76, 014302 (2007) [2] N Fotiades, RO
Nelson, M Devlin, and JA Becker, Phys Rev C77, 024306 (2008)
HD 3 4:20 PM
Using LaBr3 Gamma-ray Detectors for Precision Measurements of Nuclear Excited State
Lifetimes in the 100ps - 10ns Regime
P.H. Regan, T. Alharbi, P.J. Mason, Zs. Podolyak, C. Townsley, S. Rice, R. Britton
Centre for Nuclear and Radiation Physics, Department of Physics, University of Surrey, Guildford, GU2
7XH, UK
A.M. Bruce, O.J. Roberts, F.Browne
School of Engineering, University of Brighton, Brighton, BN2 4GJ, UK
N. Marginean, D. Filipescu, D. Deleanu, T. Glodariu, D. Ghita, R. Marginean, C. Mihai, D. Bucurescu,
A. Negret, L. Stroe, T. Sava
Horia Hulubei National Institute of Physics and Nuclear Engineering, (IFIN-HH), RO-077125
K. Mullholland, J.F. Smith
School of Engineering, University of the West of Scotland, Paisley, PA1 2BE, UK
Precision measurements of electromagnetic transition rates provide accurate inputs into generic nuclear
data evaluations and are also used to test and validate predictions of state of the art nuclear structure
models. Measurements of transition rates can be used to ascertain or rule out multipolarity assignments
for the measured EM decay, thus providing (in some cases) firm spins and parities for states between
which the transition takes place. We report on a variety of precision measurements of electromagnetic
transition rates between excited nuclear states using ’fast-timing’ gamma-ray coincidence spectroscopy
using cerium-doped lanthanum-tribormide (LaBr3(Ce)) detectors which couple high light output with
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