Conférences et séminaires » Séminaire du Dr R. GLOVER (University of York, U.K.)
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A new technique to measure two-photon decay using a segmented HPGe detector as a target.
le Jeudi 26 octobre 2006 à 16h00
Salle de Visioconférences - Bâtiment 25
IPHC, 23 rue du Loess, Strasbourg-Cronenbourg
Transitions between bound states in stable nuclei usually take place by the emission of a single photon, an internal conversion electron or an electron-positron pair. Something rarely considered by experimentalists is the possibility of two photons being emitted simultaneously in a single transition. This process is measured advantageously for transitions in which gamma-ray emission is forbidden i.e. 0+ -> 0+ transitions. Owing to experimental difficulties, two-photon emission has never been investigated in 72Ge, one of only six stable candidates for study. A novel experiment using a segmented HPGe detector as both the target and the detector has been carried out. The low lying 0+ states in 72Ge were excited through the inelastic scattering of 2.45-MeV neutrons produced using the neutron accelerator formally located at the Chalmers University of Technology. For each good event, both photons were measured simultaneously in different segments and to distinguish from random coincidences, full pulse shapes were written out and a requirement of observing the recoiling germanium nucleus, was made in the analysis. This experiment demonstrates how the development of new detector technologies not only improves existing methods, but also allows completely new techniques to be discovered.