Fissionability of nuclides in the thorium region at excitation energies to 100 MeV

Abstract

We have measured seven and compiled from the literature seventeen excitation functions for spallation residues from the interaction of 10-100 MeV protons on "'Th. Calculations of these excitation functions have been made using the theoretical framework of the pre-equilibrium exciton model of nuclear reactions to which has been added a fission option. The fit of the theory to the experimental data is excellent, lending confidence to our treatment of the competition between fission and particle emission. After showing and. discussing the comparison of the calculated and experimental results, we present representative graphs of the variations in fissionability with Z /A and with the excitation energy. NUCLEAH, +@ACT&ONS

Emission of alpha particles in the interaction of 10?85 MeV protons with48,50Ti

“…In three previous papers [1][2][3], we have investigated the interaction of 10-100MeV protons with target nuclei having A~90, 200, and 230. Two of these studies [1,2] focussed on reactions involving the emission of a preformed alpha cluster, while the third [3] concentrated on the fission process.…”

Cross sections from proton irradiation of thorium at 800 MeV

“…Titarenko and coauthors presented an especially thorough investigation of formation cross sections to the International Atomic Energy Agency in 2003 from proton irradiation of numerous targets at energies between 100 and 2600 MeV; 22 of the cross sections reported here were not measured by this previous work [9]. Fission and fragmentation cross sections [10], fission fragment energies and angular distributions [20], absolute (p,xn)-type cross sections [11], alpha emissions relevant to radioactinide production [12], and pion production [13] have been previously investigated and reported in the energy range between 0.5 and 1 GeV. Additional work targeting specific radionuclide formation cross sections has reported data for 32 P and 33 P from 600 MeV protons [14], 83,84,86 Rb [15], many Xe and Kr radioisotopes [16], and radionuclides from several actinide elements (see e.g.…”

“…Additional work targeting specific radionuclide formation cross sections has reported data for 32 P and 33 P from 600 MeV protons [14], 83,84,86 Rb [15], many Xe and Kr radioisotopes [16], and radionuclides from several actinide elements (see e.g. [17][18][19][20]) at energies hundreds of MeV above and below that used in this work. This work presents data for 65 radionuclides, several of which have not previously been measured, and is compared directly with the published values reported by Titarenko and coauthors [9] when applicable.…”

An evaluation of alpha particle clustering in heavy nuclei

“…Reduction of the value of 4) to 0.075 in the case of the two heavier nuclei (as was done in Refs. 27,28) leads to the values given in parentheses in Table 3. These values are in remarkably good agreement with the value of 5.7 clusters found by Cohen [17] in his intranuclear cascade calculation for 155 MeV protons incident upon 197Au in which he considered only the high energy portion of the alpha emission spectrum.…”

“…MeV [19][20][21][22] or the magnitude of (p,c~xn) cross sections at energies up to 100 MeV [24,25,28,29]. In the context of the pre-equilibrium approaches to such reactions, several thousand alpha clusters would be necessary in each medium weight nucleus to achieve a p-~ interaction rate which is 10% of the N-c~ rate.…”