Very heavy fission fragments produced in the spallation reaction 238U+p at

Abstract

Fission fragments from 1 A GeV 238 U ions impinging a hydrogen target are investigated by using the fragment separator FRS for magnetic selection of reaction products including ray-tracing, and E-ToF techniques. On the basis of the kinematics of the fragments, binary fission can be assigned as production process up to very heavy fragments. Fission fragments are separated and identified as far as 184 Re for the first time. Cross sections are measured and found in the range of 500 µb to 5 µb. Isobaric cross sections decrease smoothly with increasing masses. Beyond tungsten, fission fragments are hidden in the more abundant spallation evaporation residues. 283 isotopes of elements gadolinium to rhenium in the mass range 147 to 184 are observed and cross sections measured. All the fragments are formed by fission of excited parent nuclei following emission of a cascade of secondary neutrons.

Neutron production and energy deposition in fissile spallation targets studied with Geant4 toolkit

“…The significant discrepancies between calculated and experimental fission cross sections can be explained by a simplified description of the nuclear and Coulomb potentials of the target nucleus in the cascade models. For 1 GeV proton energy a very good agreement with experimental data [29][30][31][32] is reached.…”

“…The target was irradiated by 26.5 and 62.9 MeV proton beams as in the experiment by Isaev et al [28] as well as by 1 GeV proton beam as in GSI experiments [29][30][31][32].…”

Systematic comparison of ISOLDE-SC yields with calculated in-target production rates

“…In the figure 1, the results of the code for the reaction of 238 U with protons at 1 A GeV are compared with the experimental data for the reaction of the same system [19][20][21][22][23][24][25][26]27]. In the upper part, the comparison is made on the chart of nuclides, with individual nuclide production cross sections represented by colors.…”

“…During this time, an extended data base of nuclide yields has been established [1]. Recently, a series of dedicated inverse-kinematics experiments [8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27], performed at GSI, Darmstadt, have brought an important progress in our understanding of the nuclide production in reactions induced by protons and heavy ions at relativistic energies. Profiting from these data, improved nuclear reaction codes have been developed that allow performing reliable calculations on the nuclide production rates.…”

Alpha emission in krypton–emulsion collisions at 1.7AGeV

“…A few A GeV energies can be obtained at the LBL Bevalac, Dubna SF, GSI SIS, and Lanzhou CSR. In the past years, the Bevalac, SF, and SIS had important contributions for the investigations of nuclear reactions (Adamovich, 1995a, b;Bernas et al, 2006). It is expected that the CSR will play a leading role in nucleus-nucleus collisions at the low-edge of high energy in the near future.…”