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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.

Introduction All experimental studies involving charged particle induced nuclear reactions require a precise knowledge of monitor reactions. A number of well described proton induced monitor reactions exist in the lower energy range [1], which is covered by most medical cyclotrons. Concerning proton energies above 20 MeV, however, the accuracy of the monitor reactions declines as cross section data becomes scarcer. Furthermore, the growing interest in precise determination of projectile energies by comparing of ratios of monitor reaction cross sections demands new measurements and evaluations of known data for high threshold monitor radionuclides. In this work cross section measurements on the formation of 61Cu were done and energy de-pendent radionuclide ratios were calculated. Material and Methods For investigation of the natCu(p,x)61Cu reaction copper foils of natural isotopic composition (Goodfellow Ltd.) were irradiated. The targets were of 10 and 20 μm thickness, having a diameter of 15 mm. Proton bombardments up to 45 MeV incident energy were done in the stacked-foil arrangement at the accelerator JULIC of the Nuclear Physics Institute (IKP) of the Forschungszentrum Jülich. In addition to an internal irradiation possibility the cyclotron is equipped with an external target station which was used for most experiments. It can adapt standard and slanting solid target holders and is equipped with a water cooled four sector collimator and additional helium cooling of the entry foil. Several irradiations were executed. In each stack, besides copper samples, aluminium absorbers and additional nickel monitor foils were also placed, the latter for the determination of the respective beam current. The produced radioactivity of 61Cu was analysed non-destructively using HPGe γ-ray detectors (EG&G Ortec). Results and Conclusion Reaction cross sections of the natCu(p,x)61Cu process up to 45 MeV were measured and com-pared with existing data from the literature (FIG. 2). Except for the data of Williams et al. our results are in good agreement, showing a maxi-mum of about 165 mbarn at 37.5 MeV proton energy. The overall uncertainty of the new cross section data is between 8 and 10 %. In FIG. 3, the excitation functions of the relevant monitor reactions on Cu are shown. In combination with the excitation function of the natCu(p,xn)62Zn reaction, isotope ratios were calculated which can be used for determination of the proton energy within a target stack in the energy range of 22–40 MeV as described by Piel et al. [3]. FIGURE 4 shows the cross section ratio in dependence of the proton energy. Above this energy, 65Zn could be used to generate isotope ratios for energy determination, although the long half-life (T½ = 244.3 d) of that radionuclide may be a problem. Additional cross section measurements are planned in order to further strengthen the data base of this potential monitor reaction. The results of this work shall be evaluated in the framework of an ongoing Coordinated Research Project of the IAEA.

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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.

As part of our systematic comparison of (p,n) and (d,2n) reactions, the excitation functions of the Er-167(d,2n)Tm-167 production reaction and reactions leading to Tm radio-impurities were investigated up to 20 MeV. A stacked foil irradiation technique and gamma-ray spectroscopy is used. The measured excitation functions are compared with results of ALICE-D, EMPIRE-D and TALYS reaction model codes and with data from our earlier investigations on natural Er. Thick target yields and contamination levels are discussed. A comparison with other charged particle production routes for Tm-167 shows that deuteron induced reactions are not competitive. (C) 2010 Elsevier Ltd. All rights reserved.

Tm-167 (T-1/2 = 9.25 d) is a candidate radioisotope for medical therapy and diagnostics due to its Auger-electron and low-energy X- and gamma-ray emission. Excitation functions of the Er-167(p,n)Tm-167 reaction and Er-168(p,n)Tm-168, Er-167(p,2n)Tm-166, Er-166(p,2n)Tm-166 disturbing reactions were measured up to 15 MeV by using the stacked foil irradiation technique and gamma-ray spectroscopy. The measured excitation functions agree well with the results of ALICE-IPPE, EMPIRE-II and TALYS nuclear reaction model codes. The thick target yield of Tm-167 in the 15-8 MeV energy range is 6.9 MBq/mu Ah. A short comparison of charged particle production routes of Tm-167 is given. (C) 2009 Elsevier Ltd. All rights reserved.

Objectives: 167Tm (T1/2 = 9.25 d, Eg(average) = 147.2 keV, Ee(average) = 124.2 keV, ∆ = 1.425 gGy/MBqday) is a candidate radioisotope both for diagnostics and therapy. Excellent tumour imaging was obtained with 167Tm-citrate. It is on the list of nuclides potentially useful for therapy by emission of Auger-electrons. The aim of the present study is to investigate charged particle induced routes for production of 167Tm directly or through decay of 167Lu (T1/2 = 51.5 min) and 167Yb (T1/2 = 17.5 min). Methods: This work presents new experimental measurements of proton induced reactions on natEr, 167Er, 169Tm and natYb, deuteron induced reactions on natEr and 167Er and alpha-particle induced reactions on 165Ho using the activation method and stacked target irradiation technique. Irradiations of metal foil targets and sedimented oxide targets were performed at the external beam of AVF 930 cyclotron of CYRIC, CGR 560 cyclotron of VUB, and MGC 20E cyclotron of ATOMKI. Activities of the irradiated samples were measured nondestructively by high resolution gamma-ray spectrometry, without any chemical separation. Results: Excitation functions were measured using different bombarding beams for the 167Er(p,n)167Tm, 166Er(d,n)167Tm, 167Er(d,2n)167Tm, 169Tm(p,3n)167Yb, natYb(p,x)167Lu and 165Ho(a,2n)167Tm nuclear reactions for the first time. Theoretical calculations were made by means of the ALICE-IPPE, EMPIRE-II and TALYS nuclear reaction model codes to predict the excitation functions. The theoretical results were compared with the experimental data. Integral yields for production of 167Tm were calculated from the experimental cross section data. Radionuclidic purities and specific activities were deduced for the investigated processes. Conclusions: On the basis of the production yields, the required target technology and the easily accessible accelerator characteristics (particle type, energy) the most promising reactions are: at low energies (up to 20 MeV) 167Er(p,n)167Tm, at medium energies (up to 40 MeV) 169Tm(p,3n)167Yb→167Tm and 167Er(d,2n)167Tm. At higher energies (up to 100 MeV) the natYb(p,x)167Lu→167Yb→167Tm route has importance additionally allowing simultaneous production of 167Tm and the therapeutic 169Yb. Production of 167Tm via 167Er(p,n) reaction results in moderate high yield. To assure high radionuclidic purity, a highly enriched 167Er target is required (natural abundance: 22.95%). By using proton induced reactions on stable isotopes of Tm and Yb, 167Tm can be obtained indirectly in high yield through production and decay of 167Lu and 167Yb but the specific activity and the radionuclidic purity is lower compared to enriched 167Er(p,n) reaction.

The possibilities of production of the therapy-related radionuclides Nd-140, Sm-153 and Yb-169, and of Y-88, in no-carrier-added form were investigated. For Y-88 production the nuclear processes Sr-nat(p, xn)Y-88 and Rb-nat(alpha, xn)Y-88 over the energy ranges E-p = 14 -> 9 MeV and E-alpha = 18 -> 12 MeV, respectively, can be utilised, although the former reaction is superior, both in terms of yield and radionuclidic purity. For Nd-140 production the reactions Pr-141(p, 2n)Nd-140 and Ce-nat(He-3, xn)Nd-140 were investigated in detail. The optimum energy ranges are E-P = 30 -> 15 MeV and E-3He = 35 -> 20 MeV. respectively. Both processes yield high-purity Nd-140. The former reaction, however, leads to a product yield about 17 times higher than the latter reaction, and is therefore to be preferred. In the case of (SM)-S-153, investigations were done on the Eu-153(n, p)Sm-153 reaction with 14 MeV d(Be) neutrons as well as on the Nd-150(alpha, n)Sm-153 reaction. The yield of the (n, p) reaction is very low, but the (alpha, n) reaction over the energy range E-alpha = 25 -> 15 MeV offers a good potential for production of no-carrier-added (SM)-S-153 in quantities sufficient for therapeutic applications. Also for the radionuclide Yb-169 a novel route, viz. Tm-169(p, n)Yb-169 reaction, was investigated. A critical comparison of this route with the commonly used (n, gamma) route, however, showed that, due to the much higher cost involved, the (p, n) process should be utilised only when there is a real need of the high specific radioactivity product.

Activation cross sections of deuteron induced nuclear reactions on Tm-169 were measured up to 20MeV by using the stacked-foil technique. Special emphasis was on production of the internal radiotherapy related radionuclide Yb-169. No earlier experimental cross-section data on deuteron induced reactions on 169Tm were found in the literature. The experimental data were compared with the results of the nuclear model codes ALICE-IPPE and EMPIRE-II. The integral yield of the Tm-169(d,2n) Yb-169 reaction was deduced over the optimum energy range E-d = 20 -> 9 MeV. At 3.8 MBq/mu A center dot h the yield is lower than that available from the commonly used Yb-168(n,y) Yb-169 reactor method but on the other hand, it is higher than the yields from the earlier investigated Tm-169(p,n) Yb-169 and Er-nat(alpha,x) Yb-169 reactions. (C) 2007 Elsevier Ltd. All rights reserved.