No abstract
The differential cross sections of proton-pickup reactions on 40 Ca initiated by various heavy-ion projectiles have been uniformly analyzed in a distorted-wave Born-approximation model. There appears to be a spectroscopic-factor inconsistency depending on whether an odd-odd or an even-even nucleus (projectile or ejectile) participated in the reaction.PACS numbers: 25.70.Cd, 21.10.JxThe observed differential cross sections of heavy-ion-initiated single-particle transfer reactions are often not well predicted by the standard distorted-wave Born-approximation (DWBA) model calculations. Perhaps the most famous of these problems is the so-called "1 = 1 anomaly" 1-5 wherein the oscillations of the measured differential cross section are observed to occur almost precisely out of phase with those of the predicted angular distributions. Another singular failure of the DWBA calculations was noted in the reactions 208 Pb( 16 O, 15 N) 209 Bi measured between£ lab = 104 and 312 MeV, 6 » 7 The relative increase of the cross section magnitude with energy was at least a factor of 6 smaller than that predicted by the DWBA calculations. No reasonable change in the calculation parameters could account for this discrepancy. It should be noted that the predictions for heavy-ion transfer-reaction cross sections are quite sensitive to the choice of these input parameters, especially for the bound-state binding potential of the transferred particle. Conventionally a Woods-Saxon volume well is chosen and just a 5% change in the radius parameter, r 0 , for both bound states can lead to a 40%-50% change in the magnitudes of the predicted cross sections. However, this change is systematic in that all transfer cross sections are affected by about the same amount, almost independently of the incident energy or the transferred quantum numbers. To a lesser degree, the predicted cross sections are also sensitive to the parameters of the optical potentials for the entrance and exit channels. These parameters are derived from the associated elastic-scattering data, and we have found for the cases to be discussed below that different optical-potential parameter sets which give fits to the elastic data also predict about the same (within 10%-15%) transfer reaction cross sections. Hence, once the bound-state parameters are fixed, the predicted magnitudes are relatively stable as was the case for the 208 Pb( 16 O, 15 N) reaction analysis.Using new and previously published data ? we report here the discovery of a systematic discrepancy in the spectroscopic factors derived from heavy-ion proton-pickup reactions on 40 Ca leading to the ground and first excited states of 39 K" These new data include the reactions 40 Ca( 10 B, u C) 39 K at 31-MeV incident energy, and the reactions 40 Ca( 14 C, 15 N) 39 K at 41-MeV incident energy. Incoming-channel elastic data were also recorded for both cases. In Fig. 1 are shown the differential cross sections for the four transfer reactions measured in this experimento These data were taken at the Los Alamos National La...
Backward-angle excitation functions have been measured for the 12 C + 19 F elastic and inelastic scattering between E cm _ = 1A and 24.4 MeV. Three prominent gross structures (18.0, 20.7, and 22.1 MeV) are observed. The corresponding back-angle elastic angular distributions can each be fitted by a PL,O (cos#) function whose L value tracks about one unit above 'grazing-PACS numbers: 25.70.Cd, 25.70.Ef Since the recognition by Braun-Munzinger et al. l of anomalously large yields in the back-angle 28
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