Bonn 2010 – wissenschaftliches Programm

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HK: Fachverband Physik der Hadronen und Kerne

HK 56: Struktur und Dynamik von Kernen IX

HK 56.3: Vortrag

Donnerstag, 18. März 2010, 17:30–17:45, HG VII

Particle Identification for the ³²Ar Coulomb excitation Experiment. — •Olga Lepyoshkina¹ and Christoph Langer² — ¹Physik Department TU-Muenchen, Garching — ²Goethe-University, Frankfurt am Main.

For proton-rich nuclei like ³²Ar the occurrence of pronounced dipole strength is predicted in the low-energy region between 8-10 MeV excitation energy. For the ³⁴Ar the pygmy strength is expected to drop and vanish entirely for the N=Z nucleus ³⁶Ar. A kinematically complete measurement of the low-lying dipole strength was performed at GSI-Darmstadt using the LAND-R3B reaction setup. The secondary isotopes ³⁴Ar and ³²Ar were produced by fragmentation of an 800 A MeV primary ³⁶Ar beam in a Be target and separated by means of the Bρ-ΔE-Bρ method in the magnetic spectrometer (FRS). These fragments have to be identified by energy-loss and time-of-flight measurements between the FRS and the entrance to the LAND-R3B experimental hall. Coulomb excitation on a Pb target allows to investigate the pygmy and giant dipole resonance strength region. Heavy ions as well as the projectile-like protons from the decay of ^34,32Ar are tracked through a dipole field (ALADIN). The reconstruction of the excitation energy using the invariant mass technique on an event by event basis relies on the full identification of all particles and a precise measurement of their momenta. We will report on parameter calibration procedures needed for a clean particle identification of all reaction components. This work was supported by GSI F&E and BMBF (06MT9156).