Program - Brookhaven National Laboratory

fragments formed are highly neutron rich nuclei with the value of Tz = (N-Z)/2 becoming very large [4]. An
important theoretical paper by Lane and Soper [5] emphasised the importance of this increase arguing that
isobaric spin becomes a good quantum number in heavy nuclei. The large neutron excess has absolutely
pure isospin and strongly dilutes the isospin impurity of the remaining part of the system with N=Z [4,5].
Our results indicate that the fission fragments and their relative intensities have already been decided even
before the fission has occurred. The energy dependence of the fission fragments distribution will follow
from the relative intensities of the different partitions which has to be obtained from detailed calculations.
This opens the way for more precise calculations of fission fragment distributions in heavy nuclei. These
findings may have far reaching consequences for the drip line nuclei, HI fusion reactions, and calculation
of decay heat in fission phenomenon.
[1] L.S. Danu et al., Phys. Rev. C 81, 014311 (2010). [2] A. Bogachev et al., Eur. Phys. J. A34, 23 (2007).
[3] D. Rochman et al., Nucl. Phys. A 710, 3 (2002). [4] D. Robson, Science 179, 133 (1973). [5] A.M. Lane
and J.M. Soper, Nucl. Phys. 37, 663 (1962).
PD 3 4:20 PM
Accurate Fission Data for Nuclear Safety
A. Solders, M. Lantz, A. Mattera, S. Pomp, V. Rakopoulos
Division of Applied Nuclear Physics, Department of Physics and Astronomy, Uppsala University, Box
516, 751 20 Uppsala, Sweden
D. Gorelov, A. Jokinen, V.S. Kolhinen, H. Penttilä, S. Rinta-Antila
Department of Physics, P.O.Box 35 (YFL), 40014 University of Jyväskylä, Finland
The Accurate Fission data for Nuclear Safety (AlFONS) project aims at high precision measurements of
fission yields, using the renewed IGISOL mass separator facility in combination with a new high current
light ion cyclotron at the University of Jyväskylä. The 30 MeV proton beam will be used to create fast
neutron spectra and possibly also thermal spectra, before reaching the fission target. Thanks to a series
of mass separating elements, culminating with the JYFLTRAP Penning trap, it is possible to achieve a
mass resolving power in the order of a few hundred thousands [1]. The successful operation of nuclear
power plants shows that the current knowledge of the underlying nuclear physics processes is generally
sufficient. Predictions of macroscopic reactor parameters with model codes, as well as calculations of the
isotopic composition of spent nuclear fuel, are in reasonable agreement with reality. Nevertheless, more
accurate nuclear data would improve, e.g., the predictions of fuel compositions and hence both safety
and fuel economy. Furthermore, although the thermal neutron induced fission yield of 235 U is rather
well known this is generally not the case for the fission yields of other actinides, e.g. 232 Th and 239 Pu,
important in many Generation IV reactors. Therefore, reliable and accurate nuclear data is a key element
for the successful development of Generation IV reactors. We will here present the experimental setup and
scientific program of the AlFONS project in relation to existing and future reactor concepts.
[1] H. Penttilä, P. Karvonen, T. Eronen et al. ”Determining isotopic distributions of fission products with
a Penning trap.” The European Physical Journal A 44 (2010) 147-168.
PD 4 4:40 PM
Fission Fragments Yield Measurement in Reverse Kinematics at GSI, the SOFIA
Experiment
Julien Taieb, for the SOFIA collaboration
CEA DAM, Bruyeres le Chatel, France
234