Production of ³⁸K Using the ³⁵Cl(α, n)³⁸K Reaction

Abstract

The production of 3, K using the 3S Cl(o:, n) 3, K reaction is studied. The yield of 3 'K and of the interfering radionuclides produced upon irradiation of NaCl is determined as a function of the energy. Three kinds of targets were used: solid NaCl, a saturated NaCl solution and CC1 4 . The yields (at saturation) were resp. 2.45, < 0.54 and 3.2 mCi-μΑ-'. For the CC1 4 target, the 38 K is separated from CC1 4 by fixation on a cation exchanger followed by elution with a 0.9% NaCl solution. The radionuclidic purity was satisfactory for the three production methods. The CC1 4 -method was preferred since it is well suited for remote-control and can be repeated within a short time. Κ decays by positron emission with a 7.6 min half-life.It can be used [1, 2] for myocardial studies e. g. with computerised positron emission tomography. As shown in Table 1, several nuclear reactions can be used to produce 38 K. The first two reactions yield 38 Κ with low specific activity. The 40 Ar(p, 3n) 38 K reaction applied by LAMBRECHT et al.[1 ] has a yield of 5.2 mCi· μΑ" 1 for a proton energy of 32 MeV. Moreover the method developed is suitable for remote-control. Because of the high threshold energy, this reaction cannot be used with a compact cyclotron. The 40 Ca(d, α) 38 Κ reaction has also a good yield [3]. A chemical separation that lasts about 14 min is required to separate 38 Κ from coproduced Sc radionuclides. This results in a decrease of the 18 Κ activity to about 1 /4 of that at the end of the irradiation. Moreover the solid targetry and the chemical separation are not easily carried out by remote-control. The 35 CI (A, n) 38 K reaction was studied by TILBURY [4], At 15MeV the yield for a NaCl target was 0.58 mCi-μΑ" 1 . No data are available about the yield of the 35 Cl(a, n) 38 K reaction at higher energies and about the production of interfering radionuclides. The present paper gives this information. From these data practical production methods for 38 K with a compact cyclotron are deduced. These methods use resp. solid NaCl, a saturated NaCl solution and carbon tetrachloride as target. The method using carbon tetrachloride is easily carried out entirely remotecontrolled and can be repeated within a short time.Radiochimica Acta 29, 75-77 (1981) Recoil 82m Br atoms/' 2m Br isomer/(n, j) reaction in alkylbromides/' 2m Br isomer collection /Charged plate technique AbstractThe relatively simple 'Charged Plate Technique' is used for the identification of the short-lived nuclear isomer of bromine ( ,2m Br) produced by (n, y) process in alkyl bromide targets (bromoform and bromobenzene). The half-life of the collected radioactivity on either electrode corresponds to the reported value (6.2 min). The technique can be applied for enrichment and identification of short-lived nuclear species produced by nuclear transformations in non-ionic systems.