The width of the giant dipole resonance built on excited states of Cu compound nuclei

Abstract

Continuumgamma- ray spectra from the decay of59Cu formed at an excitation energy of 100 MeV and angular momenta up to 43hstrok by means of the reaction 190 MeV32S +27Al have been measured and analyzed. The parameters of the Giant Dipole Resonance (GDR) have been extracted using the statistical model. The derived GDR width confirms the sizeable broadening of this resonance in59Cu already reported in our earlier investigation at 77 MeV excitation energy (Jcrit=38hstrok). Estimates of the GDR width have been performed in the adiabatic approximation. Predicted values account qualitatively for the experimental data of59Cu as well as of the heavier isotope63Cu, in which the broadening was not seen up to 77MeV excitation (Jcrit=35hstrok). The present analysis demonstrates the strong sensitivity of the GDR to spin effects in this mass region

Highly deformed40Caconfigurations in28Si+Rousseau1, Beck2, Bhattacharya3 et al. 2002Phys. Rev. C400110View full textAdd to dashboardCite

“…FF, DI orbiting, and even molecular-resonance behavior may all be active [13] in the large-angle yields of the 28 Si + 12 C reaction [14,15]. The backangle elastic scattering of 28 Si ions from 12 C displays structured excitation functions and oscillatory angular distributions in agreement with the relatively weak absorption of this system [16]. Moreover, the resonant gross structure [14] is fragmented into very striking intermediate width resonant structure [15].…”

“…In most of the reactions studied the binary breakup of the compound nucleus (CN) is seen as either a fusionfission (FF) [1,2] or a deep-inelastic (DI) orbiting [3] process. The large-angle orbiting yields are found to be particularly strong in the 28 Si + 12 C reaction [4], as illustrated by Fig. 1 which summarizes some of the experimental results that have been collected for this system; i.e., orbiting cross sections [4,5] and total evaporation residue (ER) cross sections [6][7][8][9][10][11][12].…”

“…1 which summarizes some of the experimental results that have been collected for this system; i.e., orbiting cross sections [4,5] and total evaporation residue (ER) cross sections [6][7][8][9][10][11][12]. Since many of the conjectured features for orbiting yields are similar to those expected for the FF mechanism, it is difficult to fully discount FF as a possible explanation for the large energydamped 28 Si + 12 C yields [3][4][5]. However, FF calculations [1] significantly underpredict the cross sections measured in the carbon channel by almost a factor of 3, thus suggesting an alternative mechanism (see Fig.…”

“…Since the detection of light charged particles (LCP) is relatively simple, the analysis of their spectral shapes is another good tool for exploring nuclear deformation and other properties of hot rotating nuclei at high angular momenta. Experimental evidence for angular-momentum-dependent spectral shapes has already been extensively discussed in the literature [20][21][22][23][24][25][26][27][28][29][30][31][32][33][34] and, in particular, the 24 Mg + 16 O reaction [35], which reaches the 40 Ca CN, has been studied in detail. Strong deformation effects have also been deduced from angular correlation data for the fusion reaction 28 Si( 12 C,2α) 32 S g.s.…”

“…Experimental evidence for angular-momentum-dependent spectral shapes has already been extensively discussed in the literature [20][21][22][23][24][25][26][27][28][29][30][31][32][33][34] and, in particular, the 24 Mg + 16 O reaction [35], which reaches the 40 Ca CN, has been studied in detail. Strong deformation effects have also been deduced from angular correlation data for the fusion reaction 28 Si( 12 C,2α) 32 S g.s. at E lab = 70 MeV [36].…”