Cross sections for the proton-induced production of He and Ne isotopes from magnesium, aluminum, and silicon I. Leya a, * , H. Busemann a , H. Baur a , R. Wieler a , M. Gloris b , S. Neumann b , R. Michel b , F. Sudbrock c , U. Herpers c a Institut f  ur Isotopengeologie und Mineralische Rohstoe, ETH Z urich, Sonneggstrasse 5, CH 8092 Z urich, Switzerland b Zentrum f  ur Strahlenschutz und Radio okologie, Universit  at Hannover, Am Kleinen Felde 30, D 30167 Hannover, Germany c Abteilung Nuklearchemie, Universit  at zu K oln, Otto-Fischer-Strasse 12±14, D 50674 K oln, Germany Received 30 May 1998; received in revised form 21 July 1998 Abstract We measured integral thin target cross sections for the proton-induced production of the rare gas isotopes 3 He, 4 He, 20 Ne, 21 Ne and 22 Ne from Mg, Al, and Si from the respective reaction threshold up to 1.6 GeV. These target elements were chosen since they account for more than 50% and 95% of the cosmogenic He and Ne production in extraterrestrial matter, respectively. In order to minimize the in¯uences of secondary particles on the production of residual nuclides a so-called ``mini-stack''-approach was used instead of the well known ``stacked-foil-technique'' for all irradiation ex- periments with proton energies above 200 MeV. With this new data base a complete and consistent set of excitation functions for the proton-induced production of He and Ne isotopes is established for all target elements relevant for deciphering the cosmic ray record in extraterrestrial matter. Ó 1998 Elsevier Science B.V. All rights reserved. PACS: 13.85.L; 96.40.V Keywords: Production cross sections; Proton-induced reactions; Model calculations; Meteorites; Cosmogenic nuclides 1. Introduction Integral thin target cross sections for the pro- duction of residual nuclides by proton-induced reactions are the basic data for modeling the cos- mic ray record in extraterrestrial matter. By using purely physical models (e.g. [1±3]) the distribution of cosmogenic nuclides in meteorites can be in- terpreted with respect to the pre-atmospheric size of the meteorite, the shielding depth of the sample as well as the exposure age and terrestrial residence time of the extraterrestrial object. Of course, reli- able predictions require the input parameters to be known accurately. Our approach is based on the dierential spectra for primary and secondary particles and the excitation functions of the un- derlying nuclear reactions (e.g. [1±3]). While the dierential particle spectra can be calculated with Nuclear Instruments and Methods in Physics Research B 145 (1998) 449±458 * Corresponding author. Tel.: +41 1 63 264 23; fax: +41 1 63 21179; e-mail: leya@erdw.ethz.ch 0168-583X/98/$ ± see front matter Ó 1998 Elsevier Science B.V. All rights reserved. PII: S 0 1 6 8 - 5 8 3 X ( 9 8 ) 0 0 5 2 8 - X