Residue excitation functions from complete fusion ofO16withAu

Abstract

Evaporation residue excitation functions and o.-multiplicities from complete fusion of 0 with Au and Pb have been measured &om the fusion threshold up to 140 MeV incident energy. The data allow the conclusion that strongly overdamped motion cannot be dominant at energies in the vicinity of the fusion barrier below E' 50 MeV. At excitation energies above 50 MeV the residue cross section for 0 + Pb is much greater than predicted kom the statistical model with conventional parametrizations. The enhancement is not explained by incorporating dynamical effects into the analysis. An alternative suggestion based on deexcitation-chain dependent Sssion barriers is discussed. PACS number(s): 25.70.Gh, 25.70. Jj

Assignment of levels in 208Fr and 10- isomers in the odd-odd isotones 206At and 208Fr

“…Note also that our assignment is in fact consistent with pre-existing crossa e-mail: George.Dracoulis@anu.edu.au section measurements for the ( 16 O, xn) reactions (see, for example, refs. [6][7][8][9]). Some information on the still lighter range of isotopes, [205][206][207] Fr, has also recently been reported [10].…”

Evaporation residue cross-sections as a probe for nuclear dissipation in the fission channel of a hot rotating nucleus

“…Figuer 3 shows the evaporation residue excitation functions calculated using both the WF and CWWF dissipations. The experimental values of evaporation residue cross-section are also shown in this figure [17]. We first note that the calculated evaporation residue cross-section is very sensitive to the dissipation in the fission degree of freedom.…”

“…In fact, such an observation was made in ref. [17] where the ER cross-section obtained from standard statistical model calculation was found to decrease very steeply beyond 100 MeV of beam energy. In order to explore this point a little further, we have calculated the excitation function of the partial width for fission.…”

“…Calculation will be performed at a number of excitation energies for 224 Th formed in the 16 O+ 208 Pb system. We have chosen this system essentially because of the availability of experimental data on both evaporation residue and prescission neutron multiplicity covering the same range of excitation energies and the fact that earlier analyses of the evaporation residue excitation function have already indicated the need for a dynamical model for fission of this nucleus [15][16][17].…”

Excitation energy and nuclear dissipation probed with evaporation-residue cross sections

“…Experimental challenges to probe the nature and magnitude of nuclear dissipation have been carried out by using heavy-ion fusion reactions in the last two decades [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20]. In particular, the determination of presaddle dissipation strength is the focus of intense studies [21][22][23][24][25][26][27][28][29][30][31].…”