Alpha particles exhibit three important characteristics: scattering, ionisation and activation. This article briefly discusses those properties and outlines their major applications. Among others, -particles are used in elemental analysis, investigation and improvement of materials properties, nuclear reaction studies and medical radionuclide production. The latter two topics, dealing with activation of target materials, are treated in some detail in this paper. Measurements of excitation functions of -particle induced reactions shed some light on their reaction mechanisms, and studies of isomeric cross sections reveal the probability of population of highspin nuclear levels. Regarding medical radionuclides, an overview is presented of the isotopes commonly produced using -particle beams. Consideration is also given to some routes which could be potentially useful for production of a few other radionuclides. The significance of -particle induced reactions to produce a few high-spin isomeric states, decaying by emission of low-energy conversion or Auger electrons, which are of interest in localised internal radiotherapy, is outlined. The -particle beam, thus broadens the scope of nuclear chemistry research related to development of non-standard positron emitters and therapeutic radionuclides.

Nuclear reaction / Cross section / Thick target yield / Integral yield / Separation of positron emitter52 Mn / Ion exchange chromatography Summary. With respect to the production of no-carrieradded 52 Mn nuclear reactions on natural chromium were investigated. Cross sections of the reactions nat Cr( p, x) 48 V, 48,49,51 Cr, 52g,m Mn were determined in the proton energy range of 7.6 to 45 MeV. Additionally, production yields of 52g,m Mn and 51 Cr were measured in the energy range from 8.2 to 16.9 MeV and therefrom the calculated saturation thick target yields were obtained as (2.55 ± 0.31), (6.96 ± 0.57), and (1.53 ± 0.15) GBq/μA, respectively.For in vivo applications like PET, low toxicity is critical and sufficient activity of a radiolabelled compound mandatory. Thus, additional purification steps after separation of radionuclides and target materials have to be avoided. However, no isolation procedure has been reported in the literature so far where radiomanganese is directly obtained in a nonhazardous solution. Therefore a new separation procedure was developed utilizing the cation-exchange resin DOWEX 50W×8 (H + -form). 52g Mn was quantitatively isolated from "bulk" chromium after 3 to 4 h in non-hazardous 0.067 M ammonium citrate solution. Up to 99% of 52g Mn activity was harvested within 10 to 15 mL eluent solution with no measureable 51 Cr impurities.

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Medical radionuclide production technology is well established. There is, however, a constant need for further development of radionuclides. The present efforts are mainly devoted to nonstandard positron emitters (eg, Cu, Y, I, and Se) and novel therapeutic radionuclides emitting low-range β particles (eg, Cu and Re), conversion or Auger electrons (eg, Sn and Br), and α particles (eg, Ac). A brief account of various aspects of development work (ie, nuclear data, targetry, chemical processing, and quality control) is given. For each radionuclide under consideration, the status of technology for clinical scale production is discussed. The increasing need of intermediate-energy multiple-particle accelerating cyclotrons is pointed out.

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