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Experimental Study of the 238U(36S,3-5n)269-271Hs Reaction Leading to the Observation of 270Hs

Graeger, R.; Ackermann, D.; Chelnokov, M.; Chepigin, V.; Düllmann, Ch. E.; Dvorak, J.; Even, J.; Gorshkov, A.; Heßberger, F. P. and Hild, D., et al. (2010) In Physical Review C (Nuclear Physics) 81(6).
Abstract
The deformed doubly magic nucleus (270)Hs has so far only been observed as the four-neutron (4n) evaporation residue of the reaction Mg-26+Cm-248, where a maximum cross section of 3 pb was measured. Theoretical studies on the formation of (270)Hs in the 4n evaporation channel of fusion reactions with different entrance channel asymmetry in the framework of a two-parameter Smoluchowski equation predict that the reactions Ca-48+Ra-226 and S-36+U-238 result in higher cross sections due to lower reaction Q values, in contrast to simple arguments based on the reaction asymmetry, which predict opposite trends. Calculations using HIVAP predict cross sections for the reaction S-36+U-238 that are similar to those of the Mg-26+Cm-248 reaction. Here,... (More)
The deformed doubly magic nucleus (270)Hs has so far only been observed as the four-neutron (4n) evaporation residue of the reaction Mg-26+Cm-248, where a maximum cross section of 3 pb was measured. Theoretical studies on the formation of (270)Hs in the 4n evaporation channel of fusion reactions with different entrance channel asymmetry in the framework of a two-parameter Smoluchowski equation predict that the reactions Ca-48+Ra-226 and S-36+U-238 result in higher cross sections due to lower reaction Q values, in contrast to simple arguments based on the reaction asymmetry, which predict opposite trends. Calculations using HIVAP predict cross sections for the reaction S-36+U-238 that are similar to those of the Mg-26+Cm-248 reaction. Here, we report on the first measurement of evaporation residues formed in the complete nuclear fusion reaction S-36+U-238 and the observation of (270)Hs, which is produced in the 4n evaporation channel, with a measured cross section of 0.8(-0.7)(+2.6) pb at 51-MeV excitation energy. The one-event cross-section limits (68% confidence level) for the 3n, 4n, and 5n evaporation channels at 39-MeV excitation energy are 2.9 pb, while the cross-section limits of the 3n and 5n channel at 51 MeV are 1.5 pb. This is significantly lower than the 5n cross section of the Mg-26+Cm-248 reaction at similar excitation energy. (Less)
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Physical Review C (Nuclear Physics)
volume
81
issue
6
publisher
American Physical Society
external identifiers
  • wos:000278399700001
  • scopus:77953495382
ISSN
0556-2813
DOI
10.1103/PhysRevC.81.061601
language
English
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d0b0750b-0e96-40f8-a933-cb4e9a36e9b2 (old id 1631674)
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2010-07-21 10:44:00
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@article{d0b0750b-0e96-40f8-a933-cb4e9a36e9b2,
  abstract     = {The deformed doubly magic nucleus (270)Hs has so far only been observed as the four-neutron (4n) evaporation residue of the reaction Mg-26+Cm-248, where a maximum cross section of 3 pb was measured. Theoretical studies on the formation of (270)Hs in the 4n evaporation channel of fusion reactions with different entrance channel asymmetry in the framework of a two-parameter Smoluchowski equation predict that the reactions Ca-48+Ra-226 and S-36+U-238 result in higher cross sections due to lower reaction Q values, in contrast to simple arguments based on the reaction asymmetry, which predict opposite trends. Calculations using HIVAP predict cross sections for the reaction S-36+U-238 that are similar to those of the Mg-26+Cm-248 reaction. Here, we report on the first measurement of evaporation residues formed in the complete nuclear fusion reaction S-36+U-238 and the observation of (270)Hs, which is produced in the 4n evaporation channel, with a measured cross section of 0.8(-0.7)(+2.6) pb at 51-MeV excitation energy. The one-event cross-section limits (68% confidence level) for the 3n, 4n, and 5n evaporation channels at 39-MeV excitation energy are 2.9 pb, while the cross-section limits of the 3n and 5n channel at 51 MeV are 1.5 pb. This is significantly lower than the 5n cross section of the Mg-26+Cm-248 reaction at similar excitation energy.},
  articleno    = {061601(R)},
  author       = {Graeger, R. and Ackermann, D. and Chelnokov, M. and Chepigin, V. and Düllmann, Ch. E. and Dvorak, J. and Even, J. and Gorshkov, A. and Heßberger, F. P. and Hild, D. and Hübner, A. and Jäger, E. and Khuyagbaatar, J. and Kindler, B. and Kratz, J. V. and Krier, J. and Kuznetsov, A. and Lommel, B. and Nishio, K. and Nitsche, H. and Omtvedt, J. P. and Petrushkin, O. and Rudolph, Dirk and Runke, J. and Samadani, F. and Schädel, M. and Schausten, B. and Türler, A. and Yakushev, A. and Zhi, Q.},
  issn         = {0556-2813},
  language     = {eng},
  number       = {6},
  publisher    = {American Physical Society},
  series       = {Physical Review C (Nuclear Physics)},
  title        = {Experimental Study of the 238U(36S,3-5n)269-271Hs Reaction Leading to the Observation of 270Hs},
  url          = {http://dx.doi.org/10.1103/PhysRevC.81.061601},
  volume       = {81},
  year         = {2010},
}