Measurement of cross-sections for the (p, xn) reactions in natural molybdenum M.U. Khandaker a , M.S. Uddin a,b , K.S. Kim a , Y.S. Lee a,1 , G.N. Kim a, * a Department of Physics, Kyungpook National University, 1370 Sankyok-dong, Buk-gu, Daegu 702-701, Republic of Korea b Institute of Nuclear Science and Technology, Atomic Energy Research Establishment, Savar, GPO Box No. 3787, Dhaka 1000, Bangladesh Received 9 February 2007; received in revised form 8 May 2007 Available online 9 June 2007 Abstract Cross-sections for the residual radionuclide productions by proton-induced activation on natural molybdenum were measured up to 40 MeV by using a stacked-foil technique at the MC50 cyclotron of the Korea Institute of Radiological and Medical Sciences (KIR- AMS). This work has given a new data set for the formation of the investigated radionuclides. The present results for most of the radio- nuclides showed in general good agreement with the earlier reported data as well as the theoretical data taken from the calculations based on the ALICE-IPPE code. The integral yields for thick targets were also deduced from the measured cross-sections of the produced radionuclides. The optimum production of the 99m Tc radionuclide with minimum impurities can be obtained at the energy ranges from 10 to 23 MeV, where the production yields were obtained as 597.15 MBqlA 1 h 1 at saturation. The measured cross-sections are used for production of medically important radionuclides such as 99m Tc, 94m Tc and 93m,g Tc by using the medium-energy cyclotrons. Ó 2007 Elsevier B.V. All rights reserved. PACS: 25.40.h; 25.60.Dz Keywords: Natural molybdenum; 42 MeV proton beam; Stacked-foil activation technique; MC-50 cyclotron; Excitation functions; Integral yields 1. Introduction Nowadays, carrier free radioisotopes with a variety of half-lives are used in different fields of science and technology. Charged particle accelerators, especially the medium-energy cyclotrons are employed to produce these radioisotopes. Accurate cross-sections data are needed to determine the optimum irradiation condition for the pro- duction of these radioisotopes. At the same time, such data have importance for other applications in which medium- energy nuclear reactions are considered: astrophysics over space and environmental sciences, medical sciences (radio- isotope production, dosimetry, and radiation therapy), accelerator technology (activation of detectors, radiation protection, and on-line mass separation), space and avia- tion technology, and technology development of an accel- erator-driven system for transmutation of nuclear waste or for energy production. Molybdenum is a silvery-white, hard, but softer transi- tion metal. Molybdenum and molybdenum containing alloys are important structural materials for accelerator- driven systems, fusion reactors, and many other fields. It is also very useful as a refractory and corrosion resistant material in accelerator applications. The cross-section data on the proton-induced reactions of molybdenum are of interest as a thin layer activation technique to determine the ratio of wear, corrosion and erosion processes of molybdenum. Molybdenum is also used as a target mate- rial for the production of medically important radioiso- topes, such as 99m Tc/ 99 Mo, 96(m+g) Tc and 94m Tc [1]. About 80% of the diagnostic nuclear medicine procedures 0168-583X/$ - see front matter Ó 2007 Elsevier B.V. All rights reserved. doi:10.1016/j.nimb.2007.05.028 * Corresponding author. Tel.: +82 53 950 5320; fax: +82 53 939 3972. E-mail address: gnkim@knu.ac.kr (G.N. Kim). 1 Present address: National Fusion Research Center, Daejeon 305-333, Korea. www.elsevier.com/locate/nimb Nuclear Instruments and Methods in Physics Research B 262 (2007) 171–181 NIM B Beam Interactions with Materials & Atoms