Program - Brookhaven National Laboratory

Materials and Measurements, Retieseweg 111, B-2440 Geel, Belgium. A.Klix, Institute for Neutron
Physics and Reactor Technology, Karlsruhe Institute of Technology, D-76344 Eggenstein-Leopoldshafen,
Germany. A. Buffler, D. Geduld, Department of Physics, University of Cape Town, Private Bag,
Rondebosch 7701, South Africa. F. D. Smit, C. Vermeulen, P. Maleka, R. T. Newman, iThemba LABS, P
O Box 722, Somerset West, 7129, South Africa. R. Nolte, Physikalisch-Technische Bundesanstalt,
Bundesallee 100, D-38116 Braunschweig, Germany. A. Wallner, Faculty of Physics, Univ. of Vienna,
VERA Laboratory, Waehringer Strasse 17, A-1090 Vienna, Austria.
The process of neutrinoless double beta decay (0νββ) plays a key role in modern neutrino physics. The
experiments on the 76 Ge-0νββ-decay using germanium-semiconductors are at the forefront in this field. Due
to the extremely low count rates expected for this rare decay, any kind of background event in the detector,
especially at energies close to Qββ = 2039 keV has to be avoided. Therefore, a careful investigation on the
neutron-induced background was carried out. In this contribution the results of the search for a potentially
existing 2040.7 keV gamma-ray, which occurs due to de-excitation of the 69 th excited state of 76 Ge, will
be presented. In order to verify the existence of this weak transition the gamma rays occurring due to the
β-decay of the short living 76 Ga (T 1/2 = 32.6 s) into 76 Ge was studied. Therefore, the 14 MeV high-flux DT
neutron generator of the TU Dresden, equipped with an automatic pneumatic sample transport system,
was employed. Furthermore, first and new results on cross sections for inelastic neutron scattering into the
69 th excited state of 76 Ge, measured at the GAINS setup of the IRMM in Geel, will be shown. The decay
of 68 Ge is a major source of intrinsic background nuclides in germanium semiconductor detectors. This
nuclide is produced from other germanium isotopes in x Ge(n,jn) 68 Ge reactions induced by cosmogenic
neutrons. First measurements for the production cross section of 68 Ge with fast quasi monoenergetic
neutrons (En > 20 MeV) were performed at iThemba LABS using the activation foil method. Within
these studies on 76 Ge, the electron capture of 76 As has been observed for the first time, whose results will
be presented.
HD 7 5:30 PM
Gamma-ray Spectroscopy of 30 P
Elaine McNeice, Kiana Setoodehnia, Balraj Singh, Alan A. Chen, Jun Chen
Department of Physics and Astronomy, McMaster University, Canada
Yasuyuki Abe, Shota Fukuoka, Yoko Ishibashi, Tetsuro Komatsubara, Daisuke Nagae, Akira Ozawa
Division of Physics, the University of Tsukuba, Japan
Takehito Hayakawa
Japan Atomic Energy Agency, Japan
David Kahl, Shigeru Kubono, Hiroshi Suzuki, Hidetoshi Yamaguchi
Nishina Center, the University of Tokyo, Wako Branch at RIKEN, Japan
30 P is an N=Z=15 odd-odd nuclide whose level density is reasonably high (34 proton-bound excited states,
S(p)=5594.5 keV). Also states with isospin T=0 and T=1 coexist from the ground state upwards. Therefore
30 P spectroscopy provides an experimental test of the effect of isospin symmetry breaking on level structure.
Moreover, the proton-resonance structure of 30 P determines the 29 Si(p,γ) 30 P reaction rate at a temperature
characteristic of explosive hydrogen burning in supernovae type Ia. The 29 Si(p,γ) 30 P reaction has recently
[1] been identified as one of top ten proton-capture reactions important for supernova nucleosynthesis.
We have studied 30 P levels up to 7.2 MeV via in-beam γ-ray spectroscopy using the 28 Si( 3 He,pγ) 30 P
reaction at the University of Tsukuba Tandem Accelerator Complex in Japan. An energy level scheme was
deduced from γ-γ coincidence measurements. Furthermore, spin assignments based on measurements of
γ-ray angular distributions and γ-γ directional correlation of oriented nuclei (DCO ratios) were made for
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