Applied Radiation and Isotopes 60 (2004) 899–909 Experimental studies and nuclear model calculations on proton-induced reactions on nat Se, 76 Se and 77 Se with particular reference to the production of the medically interesting radionuclides 76 Br and 77 Br H.E. Hassan a,b , S.M. Qaim a, *, Yu. Shubin a,1 , A. Azzam b , M. Morsy b,2 , H.H. Coenen a a Institut f . ur Nuklearchemie, Forschungszentrum J . ulich GmbH, J . ulich D-52425, Germany b Cyclotron Facility, Nuclear Research Centre, Atomic Energy Authority, Cairo 13759, Egypt Received 12 December 2003; received in revised form 29 January 2004; accepted 2 February 2004 Abstract Excitation functions of the reactions nat Se(p,x) 75,76,77,82 Br, 76 Se(p,xn) 75,76 Br, 76 Se(p,x) 75 Se and 77 Se(p,xn) 76,77 Br were measured from their respective thresholds up to 40 MeV, with particular emphasis on data for the production of the medically important radionuclides 76 Br and 77 Br. The conventional stacked-foil technique was used. The samples were prepared by a sedimentation process. Irradiations were performed using the compact cyclotron CV 28 and the injector of COSY, both at the Research Centre J . ulich. In order to validate the data, nuclear model calculations were performed using the code ALICE-IPPE which is based on the preequilibrium-evaporation model. Good agreement was found between the experimental and theoretical data, except in the high-energy region where the calculated data were somewhat higher. All the measured excitation curves were compared with the data available in the literature. From the experimental data the theoretical yields of all the investigated radionuclides were calculated and plotted as a function of proton energy. The calculated yield of 77 Br from the nat Se(p,x) 77 Br process over the energy range E p =25-15 is 72.7MBq/mA h and from the 77 Se(p,n) 77 Br reaction over E p =15-6 MeV it is 86.2 MBq/mA h. The yield of 76 Br from the 76 Se(p,n) 76 Br reaction for E p =15-8 is 360.1 MBq/mA h and from the 77 Se(p,2n) 76 Br reaction for E p =28-18MeV it is 879.2 MBq/mA h. The radionuclidic impurity levels are discussed. r 2004 Elsevier Ltd. All rights reserved. Keywords: Natural and enriched selenium targets; Radiobromines Br-76 and Br-77; Medical radioisotope; Nuclear reaction; Excitation function; Nuclear model calculation 1. Introduction Among the many isotopes of bromine, the three neutron deficient ones, namely 75 Br (T 1/2 =1.6h), 76 Br (T 1/2 =16.0h) and 77 Br (T 1/2 =57.0 h), are of consider- able interest in nuclear medicine. The radionuclides 75 Br and 76 Br are positron emitters and are useful in functional studies via positron emission tomography (PET), the former for fast metabolic processes and the latter for slower processes. 76 Br is also of therapeutic ARTICLE IN PRESS *Corresponding author. Tel.: +49-2461-613282; fax: +49- 2461-612535. E-mail address: s.m.qaim@fz-juelich.de (S.M. Qaim). 1 Permanent address: Institute of Physics and Power En- gineering, Obninsk, Kaluga Region, Russia. 2 Permanent address: Department of Physics, Faculty of Science, Ain Shams University, Cairo, Egypt. 0969-8043/$-see front matter r 2004 Elsevier Ltd. All rights reserved. doi:10.1016/j.apradiso.2004.02.001