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Title: 137 Ba Double Gamma Decay Measurement with GAMMASPHERE

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, 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 backgroundmore » is a challenge. Geant4 simulations were carried out to help understand and correct for those factors.« less
 [1] ;  [1] ;  [1] ;  [1] ;  [2] ;  [3] ;  [3] ;  [3] ;  [3] ;  [4]
  1. Univ. of Massachusetts, Lowell, MA (United States). Dept. of Physics
  2. Brookhaven National Lab. (BNL), Upton, NY (United States). National Nuclear Data Center
  3. Argonne National Lab., IL (United States). Physics Div.
  4. Univ. of Massachusetts, Lowell, MA (United States). Dept. of Physics; Univ. of Surrey, Guildford (United Kingdom). Dept. of Physics
Publication Date:
OSTI Identifier:
Grant/Contract Number:
FG02-94ER40848; AC02-06CH11357; AC02-98CH10946
Accepted Manuscript
Journal Name:
EPJ Web of Conferences
Additional Journal Information:
Journal Volume: 93; Journal ID: ISSN 2100-014X
EDP Sciences
Research Org:
Argonne National Lab. (ANL), Argonne, IL (United States)
Sponsoring Org:
Country of Publication:
United States