Experimental study of the U-238(S-36,3-5n)(269-271)Hs reaction leading to the observation of (270)Hs

R. Graeger*, D. Ackermann, M. Chelnokov, V. Chepigin, Ch. E. Duellmann, J. Dvorak, J. Even, A. Gorshkov, F. P. Hessberger, D. Hild, A. Huebner, E. Jaeger, J. Khuyagbaatar, B. Kindler, J. V. Kratz, J. Krier, A. Kuznetsov, B. Lommel, K. Nishio, H. NitscheJ. P. Omtvedt, O. Petrushkin, D. Rudolph, J. Runke, F. Samadani, M. Schaedel, B. Schausten, A. Tuerler, A. Yakushev, Q. Zhi

*Corresponding author voor dit werk

Onderzoeksoutput: ArticleAcademicpeer review

40 Citaten (Scopus)

Samenvatting

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.

Originele taal-2English
Artikelnummer061601
Aantal pagina's5
TijdschriftPhysical Review C
Volume81
Nummer van het tijdschrift6
DOI's
StatusPublished - 3-jun.-2010
Extern gepubliceerdJa

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