title: Excitation functions of natGe(p,xn)71,72,73,74 As reactions up to 100 MeV with a focus on the production of 72 As for medical and 73 As for environmental studies.
abstract: Excitation functions for the formation of the arsenic radionuclides (71)As, (72)As, (73)As and (74)As in the interaction of protons with (nat)Ge were measured from the respective threshold energy up to 100 MeV. The conventional stacked-foil technique was used and the needed thin samples were prepared by sedimentation. Irradiations were done at three cyclotrons: CV 28 and injector of COSY at Forschungszentrum Jülich, and Separate Sector Cyclotron at iThemba LABS, Somerset West. The radioactivity was measured via high-resolution gamma-ray spectrometry. The measured cross section data were compared with the literature data as well as with the nuclear model calculations. In both cases, the results generally agree but there are discrepancies in some areas, the results of nuclear model calculation and some of the literature data being somewhat higher than our data. The integral yields of the four radionuclides were calculated from the measured excitation functions. The beta(+) emitting nuclide (72)As (T(1/2)=26.01 h) can be produced with reasonable radionuclidic purity ((71)As impurity: <10%) over the energy range E(p) = 18-->8 MeV; the yield of 93 MBq/microAh is, however, low. The radionuclide (73)As (T(1/2)=80.30 d), a potentially useful indicator in environmental studies, could be produced with good radionuclidic purity ((74)As impurity: <11%) over the energy range E(p) = 30 --> 18 MeV, provided, a decay time of about 60 days is allowed. Its yield would then correspond to 2.4 MBq/microAh, and GBq amounts could be produced when using a high current target.
authors.affiliation: Institut für Nuklearchemie, Forschungszentrum Jülich GmbH, D-52425 Jülich, Universität zu Köln, D-50674 Köln, Germany.
authors.forename: I
authors.initials: I
authors.lastname: Spahn
authors.forename: G F
authors.initials: GF
authors.lastname: Steyn
authors.forename: F M
authors.initials: FM
authors.lastname: Nortier
authors.forename: H H
authors.initials: HH
authors.lastname: Coenen
authors.forename: S M
authors.initials: SM
authors.lastname: Qaim
mesh_terms: D001151:Arsenic / Q000737:chemistry*; D017357:Cyclotrons; D004784:Environmental Monitoring; D005857:Germanium / Q000737:chemistry*; D007554:Isotopes / Q000737:chemistry; D011868:Radioisotopes / Q000737:chemistry*; D019275:Radiopharmaceuticals / Q000737:chemistry*
chemical_list: D007554:Isotopes; D011868:Radioisotopes; D019275:Radiopharmaceuticals; D005857:Germanium; D001151:Arsenic