Cross sections of spallation residues produced in 1A GeV 208Pb on proton reactions

Nuclear fission: a review of experimental advances and phenomenology

In the last two decades, through technological, experimental and theoretical advances, the situation in experimental fission studies has changed dramatically. With the use of advanced production and detection techniques both much more detailed and precise information can now be obtained for the traditional regions of fission research and, crucially, new regions of nuclei have become routinely accessible for fission studies. This work first of all reviews the recent developments in experimental fission techniques, in particular the resurgence of transfer-induced fission reactions with light and heavy ions, the emerging use of inverse-kinematic approaches, both at Coulomb and relativistic energies, and of fission studies with radioactive beams. The emphasis on the fission-fragment mass and charge distributions will be made in this work, though some of the other fission observables, such as prompt neutron and γ-ray emission will also be reviewed. A particular attention will be given to the low-energy fission in the so far scarcely explored nuclei in the very neutron-deficient lead region. They recently became the focus for several complementary experimental studies, such as β-delayed fission with radioactive beams at ISOLDE(CERN), Coulex-induced fission of relativistic secondary beams at FRS(GSI), and several prompt fusion-fission studies. The synergy of these approaches allows a unique insight in the new region of asymmetric fission around [Formula: see text]Hg, recently discovered at ISOLDE. Recent extensive theoretical efforts in this region will also be outlined. The unprecedented high-quality data for fission fragments, completely identified in Z and A, by means of reactions in inverse kinematics at FRS(GSI) and VAMOS(GANIL) will be also reviewed. These experiments explored an extended range of mercury-to-californium elements, spanning from the neutron-deficient to neutron-rich nuclides, and covering both asymmetric, symmetric and transitional fission regions. Some aspects of heavy-ion induced fusion-fission and quasifission reactions will be also discussed, which reveal their dynamical features, such as the fission time scale. The crucial role of the multi-chance fission, probed by means of multinucleon-transfer induced fission reactions, will be highlighted. The review will conclude with the discussion of the new experimental fission facilities which are presently being brought into operation, along with promising 'next-generation' fission approaches, which might become available within the next decade.

Analysis of the 148Gd and 154Dy Content in Proton-Irradiated Lead Targets

This work presents the determination of the ¹⁴⁸Gd and ¹⁵⁴Dy content in Pb targets irradiated by 220-2600 MeV protons. It includes the chemical separation of lanthanides, followed by the preparation of proper samples, by molecular plating technique, for α-spectrometry measurements. The experimental cross section results were compared with theoretical predictions, calculated with the INCL++-ABLA07 code. The comparisons showed a satisfactory agreement for ¹⁴⁸Gd (less than within a factor two), while measured ¹⁵⁴Dy cross sections are higher than the theoretical values.

Impact of high-energy nuclear data on radioprotection in spallation sources

The high-energy programme of the HINDAS European project has provided a large amount of experimental data and led to a better understanding of the spallation reaction mechanism and the development of more reliable spallation models. These data, or the new models, which have been implemented into high-energy transport codes, can be now used to predict with a larger confidence or, at least with a known uncertainty, some important quantities for the design of spallation sources. In this paper, examples concerning the residue production in a Pb-Bi target and the high-energy neutrons escaping the target are presented. In the first case, the activity and the amount of radioactive volatile elements that can be released, in case of a containment failure, are calculated and the level of confidence of the calculation is assessed. The second example shows that the models correctly predict the high-energy tail of the neutron spectrum, which is important for radioprotection in the facility.

Predicting total reaction cross sections for nucleon-nucleus scattering

Nucleon total reaction and neutron total cross sections to 300 MeV for 12C and 208Pb, and for 65 MeV scattering spanning the mass range, are predicted using coordinate space optical potentials formed by full folding of effective nucleon-nucleon interactions with realistic nuclear ground state densities. Good to excellent agreement is found with existing data.