New experimental data on excitation functions for practical applications of alpha induced nuclear reactions on Ta up to 30 MeV F. T ark anyi a, * , S. Tak acs a , A. Hermanne b , F. Ditr oi a , L. And o a , S.-J. Heselius c , J. Bergman c a Institute of Nuclear Research of the Hungarian Academy of Sciences (ATOMKI), P.O. Box 51, H-4001 Debrecen, Hungary b Cyclotron Laboratory, Vrije Universiteit Brussel (VUB), Brussels, B-1090, Belgium c  Abo Akademi, Cyclotron Laboratory (  AA), Turku, FIN-20500, Finland Received 19 December 2002; received in revised form 27 February 2003 Abstract Excitation functions of the nat Ta(a, xn) 184m;184g;183;182m;182mg;181 Re nuclear reactions have been investigated with stacked foil method up to 30 MeV to obtain reliable cross-section data for different applications. The earlier experi- mental data were compiled, critically evaluated and compared with the recent results to obtain recommended data. Ó 2003 Elsevier B.V. All rights reserved. PACS: 25.55.)e; 25.60.Dz; 29.25.R Keywords: Tantalum; Excitation function; Cyclotron; Rhenium isotopes 1. Introduction Activation cross-sections of low energy alpha induced nuclear reactions on Ta are important for many applications. Tantalum is one of the candi- date materials for the first wall of fusion reactors and for component parts of irradiation chambers [1]. Irradiation of bulk fusion materials produces damage and induced radioactivity. Tantalum is interesting as component material in irradiation chambers due to the large stopping power and the low neutron yield at low bombarding energies [2]. These characteristics allow to avoid damage to solid state detectors and to reduce neutron back- ground in neutron detection. Control of wear, corrosion and erosion by thin layer activation method (TLA) requires accurate knowledge of excitation functions, also of longer- lived products [3]. Activation of tantalum is not easily achieved. The low and medium energy pro- ton or deuteron induced reactions, often used for this application, result in radioisotopes with too short half-life or without proper gamma-lines to follow the wear. The main drawback of the 3 He irradiation in the case of tantalum targets is that * Corresponding author. Tel.: +36-52-417266; fax: +36-52- 416181. E-mail address: tarkanyi@atomki.hu (F. T ark anyi). 0168-583X/$ - see front matter Ó 2003 Elsevier B.V. All rights reserved. doi:10.1016/S0168-583X(03)01168-6 Nuclear Instruments and Methods in Physics Research B 211 (2003) 22–32 www.elsevier.com/locate/nimb