TY - GEN
T1 - 137Ba double gamma decay measurement with GAMMASPHERE
AU - Merchán, E.
AU - Moran, K.
AU - Lister, C. J.
AU - Chowdhury, P.
AU - McCutchan, E. A.
AU - Greene, J. P.
AU - Zhu, S.
AU - Lauritsen, T.
AU - Carpenter, M. P.
AU - Shearman, R.
N1 - Funding Information:
This work is supported by the U.S. DOE, under award number DE-FG02-94ER40848 and contracts No. DEAC02- 06CH11357 and DE-AC02-98CH10946.
PY - 2015/5/28
Y1 - 2015/5/28
N2 - The study of the electromagnetic moments (EM), and decay probability, provides detailed information about nuclear wave functions. The well-know properties of EM interactions are good for extracting information about the motion of nucleons. Higher order EM processes always occur, but are usually too weak to be measured. In the case of a 0+ → 0+ transitions [1, 2], where a single gamma transition is forbidden, the simultaneous emission of two γ-rays has been studied. An interesting opportunity to further investigate 2-photon emission phenomena is by using a standard 137Cs source populating, via β-decay, the Jπ = 11/2- isomeric state at 662 keV in 137Ba. In this case, two photon process can have contributions from quadrupole-quadrupole or dipole-octupole multipolarities in direct competition with the high multipolarity M4 decay. Since the yield of the double gamma decay is around six orders of magnitude less than the first order transition, very good statistics are needed in order to observe the phenomena and great care must be taken to suppress the first-order decay. The Gammasphere array is ideal since its configuration allows a good coverage of the angular distribution and the Compton events can be suppressed. Nevertheless the process to understand and eliminate the Compton background is a challenge. Geant4 simulations were carried out to help understand and correct for those factors. Owned by the authors, published by EDP Sciences, 2015.
AB - The study of the electromagnetic moments (EM), and decay probability, provides detailed information about nuclear wave functions. The well-know properties of EM interactions are good for extracting information about the motion of nucleons. Higher order EM processes always occur, but are usually too weak to be measured. In the case of a 0+ → 0+ transitions [1, 2], where a single gamma transition is forbidden, the simultaneous emission of two γ-rays has been studied. An interesting opportunity to further investigate 2-photon emission phenomena is by using a standard 137Cs source populating, via β-decay, the Jπ = 11/2- isomeric state at 662 keV in 137Ba. In this case, two photon process can have contributions from quadrupole-quadrupole or dipole-octupole multipolarities in direct competition with the high multipolarity M4 decay. Since the yield of the double gamma decay is around six orders of magnitude less than the first order transition, very good statistics are needed in order to observe the phenomena and great care must be taken to suppress the first-order decay. The Gammasphere array is ideal since its configuration allows a good coverage of the angular distribution and the Compton events can be suppressed. Nevertheless the process to understand and eliminate the Compton background is a challenge. Geant4 simulations were carried out to help understand and correct for those factors. Owned by the authors, published by EDP Sciences, 2015.
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U2 - 10.1051/epjconf/20159301033
DO - 10.1051/epjconf/20159301033
M3 - Conference contribution
AN - SCOPUS:84960409000
T3 - EPJ Web of Conferences
BT - CGS15 2014 - Capture GammaRay Spectroscopy and Related Topics
A2 - Zuber, Kai
A2 - Schwengner, Ronald
PB - EDP Sciences
T2 - 15th International Symposium on Capture Gamma Ray Spectroscopy and Related Topics, CGS15 2014
Y2 - 25 August 2014 through 29 August 2014
ER -