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HK: Fachverband Physik der Hadronen und Kerne

HK 25: Kernphysik / Spektroskopie

HK 25.5: Talk

Wednesday, March 14, 2007, 12:15–12:30, D

S277 - A one-nucleon knockout experiment at the FRS^* — •Peter Maierbeck for the S277 collaboration — E12, Physik Department TU München

The structure of neutron-rich nuclei is at the center of the current focus of theoretical and experimental investigations. Due to the influence of the residual interaction between valence orbitals the shell structure is expected to change locally. For calcium isotopes, a new shell closure for neutron number N=34 is predicted¹. Knockout experiments are a tool to probe the single-particle structure of nuclei and therefore to test the theoretical predictions.

In April 2006 we performed a one-nucleon knockout experiment at the FRS at GSI. A 500 MeV/nucleon ⁸⁶Kr primary beam was fragmented on a ⁹Be production target. The FRS was used to identify the primary fragments. The knockout reactions of interest were induced in a secondary target (⁹Be) placed at the intermediate focus of the FRS. The second half of the FRS provided the identification of the fragments after one-nucleon removal and the measurement of their longitudinal momentum distribution from which the angular momentum of the knocked-out nucleon is determined. For fragment identification and tracking, different detector systems (TOF, MUSIC, TPC) were used. The Miniball gamma-ray spectrometer was used to tag reaction channels in which the residual nucleus was in an excited state.

The status of the analysis and preliminary results will be presented.

¹ M. Honma et al., Phys. Rev. C65, 061301 (2002)

^* Supported by BMBF (06MT190 and 06MT238).