The $B$(E1;$1/2^+\to1/2^-$) strength for $^{11}$Be has been extracted from intermediate energy Coulomb excitation measurements, over a range of beam energies using a new reaction model, the extended ...continuum discretized coupled channels (XCDCC) method. In addition, a measurement of the excitation cross section for $^{11}$Be+$^{208}$Pb at 38.6 MeV/nucleon is reported. The $B$(E1) strength of 0.105(12) e$^2$fm$^2$ derived from this measurement is consistent with those made previously at 60 and 64 MeV/nucleon, i n contrast to an anomalously low result obtained at 43 MeV/nucleon. By coupling a multi-configuration description of the projectile structure with realistic reaction theory, the XCDCC model provides for the first time a fully quantum mechanical description of Coulomb excitation. The XCDCC calculations reveal that the excitation process involves significant contributions from nuclear, continuum, and higher-order effects. An analysis of the present and two earlier intermediate energy measurements yields a combined B(E1) strength of 0.105(7) e$^2$fm$^2$. This value is in good agreement with the value deduced independently from the lifetime of the $1/2^-$ state in $^{11}$Be, and has a comparable p recision.
Mass and energy distributions of binary reaction products obtained in the reactions {sup 22}Ne+{sup 249}Cf,{sup 26}Mg+{sup 248}Cm, {sup 36}S+{sup 238}U, and {sup 58}Fe+{sup 208}Pb have been measured. ...All reactions lead to Hs isotopes. At energies below the Coulomb barrier the bimodal fission of Hs{sup *}, formed in the reaction {sup 26}Mg+{sup 248}Cm, is observed. In the reaction {sup 36}S+{sup 238}U, leading to the formation of a similar compound nucleus, the main part of the symmetric fragments arises from the quasifission process. At energies above the Coulomb barrier fusion-fission is the main process leading to the formation of symmetric fragments for both reactions with Mg and S ions. In the case of the {sup 58}Fe+{sup 208}Pb reaction the quasifission process dominates at all measured energies.
Two-neutron interferometry measurements Pluta, J.; Bizard, G.; Désesquelles, P ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
1998, Letnik:
411, Številka:
2
Journal Article
Recenzirano
The results of analysis of two-neutron correlations in the region of small relative velocities are presented. The influence of spurious correlations on the form of correlation function is considered ...in detail. Data analysis and computer simulations were performed for a specific detector configuration with close angular position and different distances between the target and detector modules. The features of different methods of cross-talk elimination are examined. The proposed method is verified and the first results of cross-talk free correlation functions are presented for the ArAu reaction at
60
MeV
u
measured with the DEMON detector at GANIL.
The technique of intensity interferometry is proposed as a probe of the spatial configuration of two-neutron haloes. After exploring the sensitivity of interferometry to the n-n configuration, it is ...demonstrated that the application of the standard method for constructing the correlation function is not valid for halo neutrons. A new iterative method is presented and applied to measurements of the dissociation of
6He,
11Li and
14Be. The correlation functions for these systems have thus been extracted for the first time and the corresponding root-mean-square n-n separations estimated. The results are in agreement with the predictions of available three-body models.
PDF
