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Title: Excitation functions for actinides produced in the interactions of sup 31 P with sup 248 Cm

Abstract

Excitation functions have been measured for the production of various isotopes of Bk, Cf, Es, and Fm from the interactions of 174- and 239-MeV {sup 31}P projectiles with {sup 248}Cm. The isotopic distributions were symmetric and displayed full widths at half maximum of 2.5, 2.5, and 2.25 mass units for Bk, Cf, and Fm, respectively. The maxima of the isotopic distributions occur for those reaction channels which involve the exchange of the fewest number of nucleons between the target and projectile for which the calculated excitation energy is a positive quantity. The maxima of the excitation functions occur at those projectile energies which are consistent with the calculated reaction barriers based upon a binary reaction mechanism. The effects of the odd proton in the {sup 31}P projectile on the final isotopic distributions are discussed.

Authors:
; ; ; ; ; ; ; ; ; ;  [1]
  1. (Department of Chemistry, University of California, Berkeley, California (USA) Nuclear Science Division, Lawrence Berkeley Laboratory, University of California, Berkeley, California (USA))
Publication Date:
OSTI Identifier:
5128979
DOE Contract Number:
AC03-76SF00098
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physical Review, C (Nuclear Physics); (United States); Journal Volume: 44:5
Country of Publication:
United States
Language:
English
Subject:
73 NUCLEAR PHYSICS AND RADIATION PHYSICS; BERKELIUM ISOTOPES; ISOTOPE PRODUCTION; CALIFORNIUM ISOTOPES; CURIUM 248 TARGET; PHOSPHORUS 31 REACTIONS; EINSTEINIUM ISOTOPES; FERMIUM ISOTOPES; TRANSFER REACTIONS; EXCITATION FUNCTIONS; EXPERIMENTAL DATA; MEV RANGE 100-1000; ACTINIDE ISOTOPES; CHARGED-PARTICLE REACTIONS; CROSS SECTIONS; DATA; DIRECT REACTIONS; ENERGY RANGE; FUNCTIONS; HEAVY ION REACTIONS; INFORMATION; ISOTOPES; MEV RANGE; NUCLEAR REACTIONS; NUMERICAL DATA; TARGETS; 652020* - Nuclear Properties & Reactions, A=220 & above, Experimental

Citation Formats

Leyba, J.D., Henderson, R.A., Hall, H.L., Czerwinski, K.R., Kadkhodayan, B.A., Kreek, S.A., Brady, E.K., Gregorich, K.E., Lee, D.M., Nurmia, M.J., and Hoffman, D.C.. Excitation functions for actinides produced in the interactions of sup 31 P with sup 248 Cm. United States: N. p., 1991. Web. doi:10.1103/PhysRevC.44.1850.
Leyba, J.D., Henderson, R.A., Hall, H.L., Czerwinski, K.R., Kadkhodayan, B.A., Kreek, S.A., Brady, E.K., Gregorich, K.E., Lee, D.M., Nurmia, M.J., & Hoffman, D.C.. Excitation functions for actinides produced in the interactions of sup 31 P with sup 248 Cm. United States. doi:10.1103/PhysRevC.44.1850.
Leyba, J.D., Henderson, R.A., Hall, H.L., Czerwinski, K.R., Kadkhodayan, B.A., Kreek, S.A., Brady, E.K., Gregorich, K.E., Lee, D.M., Nurmia, M.J., and Hoffman, D.C.. Fri . "Excitation functions for actinides produced in the interactions of sup 31 P with sup 248 Cm". United States. doi:10.1103/PhysRevC.44.1850.
@article{osti_5128979,
title = {Excitation functions for actinides produced in the interactions of sup 31 P with sup 248 Cm},
author = {Leyba, J.D. and Henderson, R.A. and Hall, H.L. and Czerwinski, K.R. and Kadkhodayan, B.A. and Kreek, S.A. and Brady, E.K. and Gregorich, K.E. and Lee, D.M. and Nurmia, M.J. and Hoffman, D.C.},
abstractNote = {Excitation functions have been measured for the production of various isotopes of Bk, Cf, Es, and Fm from the interactions of 174- and 239-MeV {sup 31}P projectiles with {sup 248}Cm. The isotopic distributions were symmetric and displayed full widths at half maximum of 2.5, 2.5, and 2.25 mass units for Bk, Cf, and Fm, respectively. The maxima of the isotopic distributions occur for those reaction channels which involve the exchange of the fewest number of nucleons between the target and projectile for which the calculated excitation energy is a positive quantity. The maxima of the excitation functions occur at those projectile energies which are consistent with the calculated reaction barriers based upon a binary reaction mechanism. The effects of the odd proton in the {sup 31}P projectile on the final isotopic distributions are discussed.},
doi = {10.1103/PhysRevC.44.1850},
journal = {Physical Review, C (Nuclear Physics); (United States)},
number = ,
volume = 44:5,
place = {United States},
year = {Fri Nov 01 00:00:00 EST 1991},
month = {Fri Nov 01 00:00:00 EST 1991}
}
  • Excitation functions have been measured for production of isotopes of Bk through Fm in bombardments of /sup 248/Cm with 234- to 294-MeV /sup 40/Ca ions and with 239- to 318-MeV /sup 48/Ca ions. The maxima of the isotopic distributions for these elements occur at only 2 to 3 mass numbers larger for /sup 48/Ca than for /sup 40/Ca reactions. The shapes of the distributions and the half-widths of about 2.5 mass numbers are quite similar to those observed previously for reactions of /sup 16/O, /sup 18/O, /sup 20/Ne, and /sup 22/Ne with /sup 248/Cm. In general, the excitation functions formore » /sup 40/Ca show maxima near the Coulomb barrier while those for /sup 48/Ca are about 20 MeV above the barrier. The cross sections decrease rather slowly with increasing projectile energy over the energy range studied, indicating that the additional projectile energy is not manifested as excitation energy of these actinide products.« less
  • Excitation functions have been measured for the production of isotopes of Bk through Fm in bombardments of /sup 248/Cm with 97- to 122-MeV /sup 18/O ions and of isotopes of Bk through No in bombardments of /sup 249/Cf with 91- to 150-MeV /sup 18/O ions. The cross sections and widths of the mass distributions for the actinides produced in these reactions are very similar for transfer of the same numbers of nucleons. A semiquantitative comparison of the experimental results with calculations based on a simple model shows that calculations of this type are helpful in selection of projectile-target systems andmore » optimum energies for production of specific actinide isotopes and for synthesis of as yet unknown heavy isotopes and elements. Comparisons of experimental results with calculations show that, in general, about half of the kinetic energy of the projectile is transferred to the actinide product.« less
  • We have measured cross sections for the production of isotopes of Bk through No in bombardments of /sup 248/Cm with /sup 16/O, /sup 18/O, /sup 20/Ne, and /sup 22/Ne ions at energies near the Coulomb barrier. In general, the peak of the mass-yield curve for each element is about two mass units larger for /sup 18/O and /sup 22/Ne than for /sup 16/O and /sup 20/Ne, reflecting the neutron excess of the projectiles. The production cross sections and maxima of the actinide isotopic distributions are at least as favorable for production of neutron-rich actinides as those measured for irradiation ofmore » /sup 238/U and /sup 248/Cm with very heavy ions. The observation of so many neutron-rich products between the masses of the target and compound nucleus suggests a direct transfer reaction in which the product nuclide is formed with relatively low excitation which minimizes depletion from prompt fission.« less
  • Excitation functions have been measured for production of isotopes of Th through Fm in bombardments of {sup 248}Cm with 231- to 323-MeV {sup 44}Ca ions and for the production of isotopes of Th through Cm in bombardments of {sup 248}Cm with 230- to 291-MeV {sup 40}Ca ions, respectively, using radiochemical methods. Upper production cross section limits were established for nuclides that were not positively detected. The experimental data were compared with the results of previous reaction studies in the systems {sup 40}Ca+{sup 248}Cm and {sup 48}Ca+{sup 248}Cm. The half-widths of the Gaussian isotopic distributions were about 2.5 mass numbers formore » above-target elements and 5 to 5.5 mass numbers for below-target elements in all three systems. The majority of the cross section for the production of above-target nuclides was assigned to predominantly quasielastic reactions, whereas below-target nuclides were formed in deeply inelastic and asymmetric quasifission reactions. The maxima of the isotopic distributions were shown by others to closely follow the minimum of the potential energy surface in experiments with {sup 48}Ca, whereas in reactions with {sup 40}Ca and {sup 44}Ca we found that a transfer of 4 to 5 protons in either direction was required to reach the minimum in potential energy.« less
  • Excitation functions have been measured for isotopes of Bk, Cf, Es, and Fm produced from the interactions of 207- to 286-MeV {sup 40}Ar ions with {sup 248}Cm. The measured isotopic distributions were found to be essentially symmetric with full widths at half maximum between 2.0 and 3.5 mass units. These results are comparable to those obtained in previous studies using {sup 40,44,48}Ca with {sup 248}Cm. The maxima of the isotopic distributions from the {sup 40}Ar-{sup 248}Cm system show shifts, to both heavier and lighter mass numbers, of 0 to 2 mass units relative to the corresponding maxima of the isotopicmore » distributions from the {sup 40,44,48}Ca-{sup 248}Cm systems.« less