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HK: Fachverband Physik der Hadronen und Kerne

HK 45: Elektromagnetische und Hadronische Sonden

HK 45.4: Vortrag

Donnerstag, 15. März 2007, 15:00–15:15, A

Exclusive Measurement of the p + ⁶Li → ⁷Be + η reaction — •Daniil Kirillov for the GEM collaboration — Institut für Kernphysik, FZ Jülich, 52425 Jülich, Germany

While the low energy η-nucleon interaction is well studied, the data for η-nucleus interaction is scarce. Practically no measurement exists on the η-nucleus final state interaction for nuclei heavier than ⁴He. The reaction p + ⁶Li → ⁷Be + η was measured by GEM in order to shed some light on the interaction of η-meson and ⁷Be and, possibly, find glimpses of a bound state.

Experimentally, the reaction p + ⁶Li → ⁷Be + η can be investigated by detecting either η decay products or the heavy recoil nucleus ⁷Be, which is convenient, when the particles are emitted in a small forward cone. In this case, however, the target thickness (counting rate) is limited by the energy resolution. On the other hand the decay of the excited ⁷Be to triton and alpha-particle allows us to select only the ground and first excited ⁷Be states.

The experiment took place in September 2006. The Big Karl spectrometer was used as a tool for our measurements. At the focal plane, a new detection system was built, since the standard focal plane detectors are not suitable for such strongly ionizing particles. Low pressure avalanche chambers and scintillator layers were places into the huge vacuum box. This detection system was used to identify the particles and reconstruct their four-momentum vectors at the target.

The ⁷Be missing mass spectra is to be reconstructed. First results will be presented.