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Introduction Radioisotopes of bromine are of special interest for nuclear medical applications. The positron emitting isotopes 75Br (T½ = 1.6 h; β+ = 75.5 %) and 76Br (T½ = 16.2 h; β+ = 57 %) have suitable decay properties for molecular imaging with PET, while the Auger electron emitters 77Br (T½ = 57.0 h) and 80mBr (T½ = 4.4 h) as well as the β−-emitter 82Br (T½ = 35.3 h) are useful for internal radiotherapy. 77Br is additionally suited for SPECT. The isotopes 75Br, 76Br and 77Br are usually produced at a cyclotron either by 3He and α-particle induced reactions on natural arsenic or by proton and deuteron induced reactions on enriched selenium isotopes [1]. As target mate-rials for the latter two reactions, earlier ele-mental selenium [2] and selenides of Cu, Ag, Mn, Mo, Cr, Ti, Pb and Sn were investigated [cf. 3–7]. Besides several wet chemical separation techniques the dry distillation of bromine from the irradiated targets was investigated, too [cf. 2, 4, 5]. However, the method needs further development. Nickel selenide was investigated as a promising target to withstand high beam currents, and the dry distillation technique for the isolation of n.c.a. radiobromine from the target was optimized. Material and Methods Crystalline Nickel-(II) selenide (0.3–0.5 g) was melted into a 0.5 mm deep cavity of a 1 mm thick Ni plate covered with a Ni grid. NiSe has a melting point of 959 °C. For development of targeting and the chemical separation, natural target material was used. Irradiations of NiSe were usually performed with protons of 17 MeV using a slanting water cooled target holder at the cyclotron BC1710 [8]. For radiochemical studies a beam current of 3 µA and a beam time of about 1 h were appropriate. To separate the produced no-carrier-added (n.c.a.) radiobromine from the target material a dry distillation method was chosen. The apparatus was developed on the basis of a dry distillation method for iodine [cf. 9,10] and optimized to obtain the bromine as n.c.a. [*Br]bromide in a small volume of sodium hydroxide solution. Changing different components of the apparatus, the dead volume could be minimized and an almost constant argon flow as carrier medium was realized. Various capillaries of platinum, stainless steel and quartz glass with different diameters and lengths were tested to trap the radiobromine. Results and Conclusion Nickel selenide proved successful as target material for the production of radiobromine by proton irradiation with 17 MeV protons. The target was tested so far only at beam currents up to 10 µA, but further investigations are ongoing. The optimized dry distillation procedure allows trapping of 80–90 % of the produced radiobromine in a capillary. For this purpose quartz glass capillaries proved to be most suitable. After rinsing the capillary with 0.1 M NaOH solution the activity can be nearly completely obtained in less than 100 µL solution as [*Br]bromide immediately useable for radiosynthesis. So, the overall separation yield was estimated to 81 ± 5 %. The radionuclidic composition and activity of the separated radiobromide was measured by γ-ray spectrometry. Due to the use of natural selenium the determination of the isotopic purity was not meaningful, but it could be shown that the radiobromine was free from other radioisotopes co-produced in the target material and the backing. The radiochemical purity as well as the specific activity were determined by radio ionchromatography. Further experiments using NiSe produced from nickel and enriched selenium are to be per-formed. The isotopic purity of the produced respective radiobromide, the production yield at high beam currents and the reusability of the target material have to be studied.

Objectives: The longstanding interest in radioactive bromine for diagnostic and therapeutic nuclear medicalapplications results from the various decay properties of the radiobromine isotopes as well as from the versatilebromine chemistry. The production of radiobromine isotopes via deuteron induced processes on selenium appearsas an alternative to proton induced reactions. As there are currently no data available in literature, thecorresponding cross sections for the nuclear reactions natSe(d,xn)75,76,77,78,82Br were measured for the first time.Furthermore new cross section measurements for (α,xn)-reactions on arsenic were done, as the available data stillexhibited some gaps.Methods: Thin irradiation samples were prepared by sedimentation of elemental selenium or arsenic powder fromethanolic suspension, respectively. Aluminium foils of different thickness were used as backing material. Thesamples were irradiated as stacked-foil arrangements, together with aluminium and copper foils as degraders andaluminium, copper, titanium and nickel foils for beam monitoring. All generated radioactivity was measured by γ-ray spectrometry using well calibrated HPGe-detectors and subsequent peak area analysis. Cross sections fornatSe(d,xn)78Br processes had to be determined by decay curve analysis, as 78Br (T1/2 = 6.46 min; β+= 92%,EC = 8%) shares its only high abundant γ-ray with the co-produced radionuclide 78As (T1/2 = 1.5 h; β-= 100%).Additionally cross sections for the formation of non-isotopic side products via (d,x) processes were determined.Results: Reaction cross sections for deuteron induced processes on natural selenium were measured in the energyrange < 41 MeV. Since natural selenium consists of 6 stable isotopes of different abundances, the excitationfunctions for natSe(d,xn) processes show several maxima (see Fig. 1). In the energy range 40 → 20 MeV theformation of 77Br (T1/2 = 57.036 h; EC > 99%) is favoured with cross sections up to 150 mb, whereas anappreciable formation of 82Br (T1/2 = 35.30 h; β-= 100%) via the 82Se(d,2n)-process occurs exclusively in theenergy range below 20 MeV. New cross section measurements for alpha induced reactions on arsenic in the energyrange < 38 MeV complement the available data [1]. Based on those, the production yields for all consideredradionuclides will be discussed.Conclusions: New cross section data for the production of radiobromine isotopes by deuteron and alpha inducednuclear reactions as alternative to proton bombardment were determined by irradiation of elemental selenium andarsenic. Reaction cross sections for deuteron induced processes on natural selenium were measured for the firsttime. In comparison with the corresponding proton induced reactions [2,3], however, cross sections fornatSe(d,xn)75,76,77Br are 10 - 30% lower.

The 13.2 h half-life radioisotope I-123 is widely used in clinical nuclear medicine diagnosis. At present it is mostly produced in nca form by proton irradiation of highly enriched Xe-124 in dedicated gas target set-ups and relying on the decay chain Cs-123-Xe-123-I-123. Depending on the irradiation conditions contamination with long-lived Te-121, a daughter product of the co-produced rather short lived I-121, occurs and can limit the useful shelf life of the I-123 solution. Excitation function of the Xe-124(p,alpha)I-121, Xe-124(p,2n)Cs-123 and Xe-124(p,2p)Xe-123 reactions are measured up to 35 MeV using the stacked gas cell technique and high-resolution gamma-ray spectrometry. The experimental data were compared with the earlier literature values, with new results of the ALICE-IPPE and EMPIRE-II codes and with the data taken from the TENDL-2009 database. Existing discrepancies in cross-section data are largely solved and new recommended values are proposed. From fits to the new excitation curves integral I-123 batch yields and Te-121 contaminations for realistic production conditions are derived. Optimization of irradiation and cooling times and energy degradation in the target can strongly influence the contamination level. (C) 2010 Elsevier Ltd. All rights reserved.

Some production aspects of the Auger electron emitter (193m)Pt (T(1/2) = 4.33 d) through the (192)Os(alpha, 3n)-process were investigated. Relatively thick targets of 99.65% enriched (192)Os, prepared by pressing or electrolytic deposition, were irradiated with 40 MeV alpha-particles for 3 h at a nominal beam current of 1.6 mu A. The radioplatinum formed was chemically separated with a yield of 90% and the expensive target material was recovered with a yield of 85%. The radioactivity of (193m)Pt was determined by high resolution X-ray spectrometry. The radionuclidic purity of (193m)Pt amounted to 99%, the level of (195m)Pt and (191)Pt impurities being each 0.5%. The batch yield of (193m)Pt achieved was about 10 MBq with a specific activity of 1 GBq/mu g Pt. Both the batch yield and the specific activity could be appreciably increased through improved targetry. A comparison of the cyclotron and reactor production routes of (193m)Pt shows that the (n, gamma) reaction leads to high production yields but the alpha-particle induced reaction results in a product of higher radionuclidic purity and four orders of magnitude higher specific activity of (193m)Pt.

For production of the medically interesting beta(+)-emitter Co-55 (T-1/2 = 17.6 h) via the Fe-54(d, n)-reaction, 91.6% enriched (Fe2O3)-Fe-54, mixed with Al powder, was pressed to a pellet which could be irradiated with 14 MeV deuterons at 4 muA in a water-cooled target system. A separation method was developed which led to > 99.9% pure Co-55 and allowed a recovery of the enriched target material. For a target thickness of E-d = 12.6 --> 5 MeV, the experimental thick target yield of Co-55 after chemical separation amounted to about 13 MBq/muA.h, which is about 60% of the theoretical value. In a 3 h irradiation at 4 muA, the batch yield of Co-55 achieved was 160 MBq (4.3 mCi). An 8 h irradiation could lead to a batch yield of about 400 MBq. The Fe-54(d, n) reaction leads to the highest purity Co-55 but it is essential that the isotopic enrichment of the target is not less than 90%. In addition to the production work, cross sections were measured for the Fe-54(d, t)Fe-53 and Fe-54(d, alpha)Mn-52m reactions using the standard stacked-foil technique and high-resolution gamma-ray spectrometry. The cross section ratio for the isomeric pair Mn-52mg is discussed in terms of the spins of the two states involved and the increasing projectile energy.

This study combines both transmutational changes and accelerated damage by simulation of irradiating tungsten with 16, 30 and 45 MeV protons. Comparative results indicate 30 MeV to be most optimal amongst the three, for uniformity of combined damage. Finally, the results were compared against fission reactor calculations and DEMO relevant compositional changes. Using 30 MeV protons, for damages of 1 dpa equivalent, the rhenium content is calculated as 401 appm. This compares well against appm induced within a DEMO reactor and is better than estimated 50,000 appm for a fission reactor. Using higher energy protons, the recoils are expected to behave similar to neutron displacement damage creation. Additionally, the study suggests near constant and comparable damage for sample thickness’s upto 500 µm.