Program - Brookhaven National Laboratory

Society, Vol. 59, No. 2, August 2011, p. 1597-1600. [3] F. B. Brown, R. F. Barrett, T. E. Booth, J. S. Bull,
L. J. Cox, R. A. Forster, T. J. Goorley, R. D. Mosteller, S. E. Post, R. E. Prael, E. C. Selcow, A. Sood,
and J. Sweezy, Trans. Am. Nucl. Soc. 87, 273 (2002). [4] ”FLUKA: a multi-particle transport code”, A.
Ferrari, P.R. Sala, A. Fasso, and J. Ranft, CERN-2005-10 (2005), INFN/TC 05/11, SLAC-R-773.
Session PB Cross Section Measurements
Thursday March 7, 2013
Room: Met West at 3:30 PM
PB 1 3:30 PM
Study of Nuclear Reactions Between 235 U Target and Proton or 3 He Beam at Low Energies
K. Helariutta, S. Salminen-Paatero
University of Helsinki, Department of Chemistry, Laboratory of Radiochemistry, Helsinki, Finland
E. Gromova, V. Jakovlev
V.G. Khlopin Radium Institute, Department of Physics, Laboratory of Nuclear Reactions and Nuclear
Medicine, St. Petersburg, Russia
J. Bergman, S.-J. Heselius
˚Abo Akademi University, Turku PET Centre, Accelerator laboratory, Turku, Finland
H. Penttilä, J. Rissanen, A. Saastamoinen
University of Jyväskylä, Department of Physics, Accelerator laboratory, Helsinki, Finland
Short-lived isotopes of Np and Pu, and especially the nuclides 236 Pu (t 1/2=2.858 y) and 235 Np (t 1/2=396.1
d), are convenient tracers e.g. for studying the distribution and the biological pathways of long-lived
plutonium and neptunium released in the environment e.g. in nuclear accidents. Recently, the commercial
availability of these isotopes has anyhow become limited. Our group has studied systematically the ways
to produce different short-lived Np and Pu isotopes [1-2], in order to be able to prepare the needed
tracers for our own use. For this purpose, it is important to have all the needed data to be able to
select suitable irradiation conditions in case there are limitations either on target or beam availability,
or special requirements on the radiochemical purity of the tracer. The studies have involved measuring
cross sections of several direct and indirect reaction paths between 236,238 U, 237 Np targets and p and 3He
beams. In this work, we have used a set of highly enriched 235 U targets and have extended the study to
235 U(p,xn) reactions in the energy range of 6.5 - 16.1 MeV and 235 U( 3 He,xnyp) reactions in the energy
range of 20.6 - 42 MeV. These reactions lead to radiochemically interesting short-lived actinides 236 Pu,
237 Pu, 235 Np, 234 Np, and 236m Np. 1 mg/cm 2 thick 235 U targets stacked with energy-degrader foils were
irradiated with protons using the accelerators in the Laboratory of Radiochemistry, University of Helsinki
(cyclotron IBA10/5) and in the Accelerator Laboratory of ˚Abo Akademi University (cyclotron MCG-20),
and with 3 He in the Accelerator Laboratory of University of Jyväskylä (cyclotron K130). After irradiation
the targets were measured with gamma and alpha spectrometers. The measurements were followed by
dissolution of the targets and chemical separation of fission products, neptunium and plutonium from the
target material. The radioactivities of the chemically separated reaction products were measured and the
reaction cross sections calculated. The data obtained from the experiment resulted in earlier unknown
excitation functions on proton/ 3 He induced nuclear reactions in 235 U.
[1] J. Aaltonen, P. Dendooven, E.A. Gromova, S.-J. Heselius, V.A. Jakovlev, W.H. Trzaska, Radiochimica
Acta 91 (2003) 557. [2] J. Aaltonen, E.A. Gromova, K. Helariutta, V.A. Jakovlev, W.H. Trzaska, J.
Huikari, V.S. Kolhinen, S. Rinta-Antila, Radiochimica Acta 93 (2005) 377.
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