Bochum 1998 – scientific programme

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HK: Hadronen und Kerne

HK 64: Radii, Masses, Heavy Nuclei

HK 64.1: Group Report

Thursday, March 19, 1998, 14:00–14:30, E

Determination of the proton and neutron densities at the nuclear periphery with p X-rays and p–nucleus reactions — •R. Schmidt¹, T. Czosnyka², T. von Egidy¹, K. Gulda³, F.J. Hartmann¹, J. Jastrzȩbski², B. Ketzer¹, B. Kłos⁴, J. Kulpa⁵, W. Kurcewicz³, P. Lubiński², P. Napiorkowski², L. Pieńkowski², R. Smolańczuk⁵, A. Trzcińska², E. Widmann⁶, and S. Wycech⁵ — ¹Physik-Department, TU M"unchen — ²Heavy Ion Laboratory, Warsaw University — ³Institute of Experimental Physics, Warsaw University — ⁴Physics Department, Silesian University, Katowice — ⁵Soltan Institute for Nuclear Studies, Warschau — ⁶CERN, Genf

The nucleon density at the nuclear periphery has been investigated with two different methods. The first one is the measurement of the energy shift and the width of antiprotonic X-ray lines. Besides various other nuclids the X-rays of the isotopes ¹⁷²Yb and ¹⁷⁶Yb have been measured very extensively. From these data the absorption widths of six antiprotonic levels and the shifts of the lowest visible transitions could be determined.
The second method is the determination of the yield of the annihilation products from the reaction of the antiprotons with nuclei. From the yield of the products with one neutron or one proton less than the target nucleus the neutron–to–proton density ratio at a distance of 3 fm from the nuclear surface can be determined [1]. This method was extended to short–lived product nuclei with a half–live down to 5 s. This allowed to measure the ratio for the nuclei ⁴⁸Ca, ¹⁰⁰Mo, ¹⁰⁴Ru, ¹¹⁶Cd, ¹¹²Sn, and ¹²⁴Sn. The results have been compared with the results of HFB–calculations.

[1] P. Lubiński, et al., Phys. Rev. Lett. 73, 3199 (1994)