Neutron Pickup Research Articles

Neutron transfer in 7Li+205Tl system

Neutron transfer cross sections for 7Li+205Tl system were measured near Coulomb barrier energies using online γ\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\gamma $$\\end{document}-ray detection technique. One neutron stripping, two neutron stripping, and one neutron pickup cross sections have been extracted and are compared with the Coupled Reaction Channel (CRC) calculations. The systematics of one and two neutron stripping and pickup cross sections with a 7Li projectile on several targets show an approximate universal behaviour. A comparison of integrated neutron transfer cross sections with complete and incomplete fusion cross sections available with 7Li projectile is presented to understand the systematic behaviour. The neutron transfer along with cumulative sum of complete and incomplete fusion was found to explain the estimated reaction cross section in 7Li+205Tl system.

Dissipation by transfer and its influence on fusion

A new version of the CCQEL code has been developed by upgrading the method of coupling of transfer channels during fusion and backscattering processes. In particular, the number of transfer reactions included has been increased and the dependence of the strength of transfer coupling on the transferred particle and experimental Q-value distribution was introduced. The upgraded code was employed for the investigation of the influence of transfer on the smoothing of the measured quasielastic barrier distribution (Dqe) of the 24Mg + 92Zr and 20Ne + 208Pb systems and found interesting discrepancies with respect to the standard approximations. The study with the upgraded code indicates the transfer responsible for generating strongly excited targets as the leading cause of the smearing of the barrier distribution, even in the case of negative ground state to ground state Q value (Qgg). The smoothing observed in the barrier distribution is dominated rather by one neutron transfer, despite the negative Qgg value for this reaction and the positive Qgg value for two-neutron transfer. Of particular interest is the case of the 20Ne + 208Pb, where the smoothing of the Dqe is mainly influenced by the one neutron pick-up at the beam energy above the barrier, while the one neutron pick-up and one proton stripping transfers are dominant for lower beam energy. These results highlight the importance of the transfer coupling dependence on the experimental Q-value distribution and, consequently, on the projectile kinetic energy.

Insights from multinucleon transfer reactions in 206Pb+118Sn

Multinucleon transfer reactions for the 206Pb +118 Sn system were measured at Elab = 1200 MeV using the PRISMA large solid-angle magnetic spectrometer. The experiment was conducted at laboratory angles around the grazing angle, covering an angular range of approximately 20°. The resulting differential and total cross sections, along with Q-value distributions for various neutron and proton pick-up and stripping channels, are presented. The Q-value distributions suggest a transition from quasi-elastic to deep inelastic collision processes, particularly in channels involving nucleon transfers. The experimental results have been compared with GRAZING code calculations, showing good agreement for few-nucleon transfer channels, while channels with large nucleon transfers are underestimated, indicating the involvement of more complex processes.

Effects of deuteron breakup and nucleon-transfer reactions on d+^{11}B elastic scattering

A set of experimental data consisting of angular distributions of d+^{11}B elastic and inelastic scattering and (d,t) reaction obtained at deuteron energy of 14.5 MeV as well as data sets for (d,p) (E_d = 21.5 MeV), (d,n) (E_d = 15.4 MeV) and (d,^3He) (E_d = 11.8 MeV) nucleon transfer reactions were analysed using the continuum-discretized coupled-channel (CDCC) and coupled-reaction channel (CRC) methods. It was found that at forward scattering angles the elastic scattering data are well described by parameter-free CDCC calculations which include breakup of the deuteron, but at more backward angles virtual effects due to target excitation and neutron-transfer reactions play an important role. The strongest effects are due to the excitation of ^{11}B and the neutron pickup reaction, reflecting their large cross sections. The effects induced by proton-transfer reactions are found to be negligible.

Transfer reactions in Pb206+Sn118 : From quasielastic to deep-inelastic processes

We measured multinucleon transfer reactions for the $^{206}\mathrm{Pb}+^{118}\mathrm{Sn}$ system at ${E}_{\mathrm{lab}}=1200$ MeV by employing the large solid angle magnetic spectrometer PRISMA. Differential and total cross sections and $Q$-value distributions have been obtained for a variety of neutron and proton pick-up and stripping channels. The $Q$-value distributions show how the quasielastic and deep inelastic processes depend on the mass and charge of the transfer products. The corresponding cross sections have been compared with calculations performed with the grazing code. An overall good agreement is found for most of the few nucleon transfer channels. The underestimation of the data for channels involving a large number of transferred nucleons indicates that more complicated processes populate the given isotopes.

Exploiting dissipative reactions to perform in-beam γ -ray spectroscopy of the neutron-deficient isotopes Ca38,39

The neutron-deficient Ca isotopes continue to attract attention due to their importance for testing isospin symmetry and their relevance in capture reactions of interest for nova nucleosynthesis and the shape of light curves in Type I x-ray bursts. To date, spectroscopic information on $^{38,39}\mathrm{Ca}$ is largely limited to data on lower-spin excited states. Here, we report in-beam $\ensuremath{\gamma}$-ray spectroscopy of complementary higher-spin, complex-structure states in $^{39}\mathrm{Ca}$ populated in fast-beam-induced, momentum-dissipative processes leading to neutron pickup onto excited configurations of the projectile, $^{9}\mathrm{Be}(^{38}\mathrm{Ca}^{*},^{39}\mathrm{Ca}+\ensuremath{\gamma})X$. Such a dissipative reaction was recently characterized for the case of inelastic scattering of $^{38}\mathrm{Ca}$ off $^{9}\mathrm{Be}, ^{9}\mathrm{Be}(^{38}\mathrm{Ca}, ^{38}\mathrm{Ca}+\ensuremath{\gamma})X$. Additional data and discussion on the nuclear structure of $^{38}\mathrm{Ca}$ is also presented. An explanation for the more-complex-structure states, populated with small cross sections in one-nucleon knockout reactions, and observed in the tails of their longitudinal momentum distributions, is also offered.

Reaction channel contributions to the proton +Pb208 optical potential at 40 MeV

Background: Reaction channel coupling substantially modifies the real and imaginary nucleon-nucleus interactions for nuclei of $Z=20$ or less in ways that cannot be represented as uniform renormalizations of folding model potentials. For such nuclei coupling to inelastic channels also contributes. This raises the question of the effect of these couplings for heavier target nuclei.Purpose: To establish and characterize the contribution to the proton-nucleus interaction generated by coupling to neutron pickup (outgoing deuteron) channels for 40 MeV protons on the heavy closed shell nucleus $^{208}\mathrm{Pb}$. To identify and evaluate the consequent dynamical non-locality.Methods: Coupled reaction channel (CRC) calculations provide the elastic channel $S$-matrix ${S}_{lj}$ due to the included processes. Inversion of ${S}_{lj}$ will produce the local potential that would yield, in a single channel calculation, the elastic scattering observables from the CRC calculation. Subtracting the bare potential of the CRC calculations gives a local and $l$-independent representation of the dynamical polarization potential (DPP). From the DPPs due to various combinations of channel couplings, the influence of dynamically generated nonlocality can be identified.Results: Coupling to deuteron channels generates a repulsive component for the real potential and an absorptive component for the imaginary term. The radial shapes of both terms were modified in ways that could not be represented by uniform renormalization; the rms radius of the real part was substantially altered. Evidence of the dynamical nonlocality of the DPP due to pickup is provided by the nonadditivity of contributions of different couplings and other effects. For the doubly closed shell $^{208}\mathrm{Pb}$ coupling to low-lying (nongiant) collective states has a very small effect on elastic scattering, making a negligible contribution compared with pickup, and was not included.Conclusions: The DPPs established here strongly challenge the notion that folding models, in particular local density models, provide a satisfactory description of elastic scattering of protons from heavy nuclei. Coupling to neutron pickup channels induces dynamical nonlocality in the proton optical model potential with implications for direct reactions.

Elastic, inelastic, and one-neutron transfer angular distributions of Li6+Sn120 at energies near the Coulomb barrier

The elastic scattering, first ${2}^{+}$ and ${3}^{\ensuremath{-}}$ target inelastic excitation and one neutron pickup angular distributions for the $^{6}\mathrm{Li}+^{120}\mathrm{Sn}$ reaction have been measured for three bombarding energies (19, 24, and 27 MeV). Data have been analyzed through coupled-channel calculations and continuum-discretized coupled-channel calculations extended to include target excitation. In general, both theoretical models give a reasonable description of the data. For the elastic and inelastic angular distributions taken at ${E}_{\mathrm{lab}}=24$ and 27 MeV, the continuum-discretized coupled-channel results are slightly better in comparison to the coupled-channel predictions. For the elastic and inelastic angular distributions measured at ${E}_{\mathrm{lab}}\phantom{\rule{4pt}{0ex}}=19$ MeV, the effect of the break-up channel seems to be quite important. At this energy, the elastic scattering data can be well explained by coupled channel calculations in which a strong absorptive optical imaginary potential is considered. In particular, the continuum-discretized coupled-channel theoretical results provided the best description of the ${3}^{\ensuremath{-}}$ excitation data at 19 MeV.

Two-proton decay from α -cluster states in C10 and N11

Two-proton decay from excited states in $^{10}\mathrm{C}$ and $^{11}\mathrm{N}$ has been characterized from an analysis of the $2p+2\ensuremath{\alpha}$ and $3p+2\ensuremath{\alpha}$ exit channels. Data from four previously published invariant-mass studies associated with inelastic excitation, multinucleon knockout, and neutron pickup reactions have been considered. A rotational band in $^{10}\mathrm{C}$ was identified built on the second ${0}^{+}$ state which has strong $\ensuremath{\alpha}$-cluster molecular structure. The members of this band were tentatively identified up to ${J}^{\ensuremath{\pi}}={4}^{+}$ and all identified states have a prompt $2p$ decay branch. The spins of the ${0}^{+}$ and ${2}^{+}$ members were deduced from comparisons of the momentum correlations in their $2p$ branches to those from known $2p$ emitters. The ${2}^{+}$ and the tentative ${4}^{+}$ members are both above the $\ensuremath{\alpha}$ threshold and exhibit large reduced decay widths for $\ensuremath{\alpha}$ emission. This band exhibits a similar moment of inertia to its analog in the mirror nucleus $^{10}\mathrm{Be}$. Evidence is also presented for a molecular band in $^{11}\mathrm{N}$ built on the second $3/{2}^{\ensuremath{-}}$ state which $2p$ decays. Tentative members of this band have been assigned up to ${J}^{\ensuremath{\pi}}=9/{2}^{\ensuremath{-}}$ and their excitation energies also match their likely analogs in the mirror nucleus $^{11}\mathrm{Be}$.

Investigation of neutron transfer in Li7+Sn124 system

The relative importance of neutron transfer and breakup process in a reaction around Coulomb barrier energies has been studied for the $^{7}\mathrm{Li}+^{124}\mathrm{Sn}$ system. Coupled channel calculations have been performed to understand the one neutron stripping and pickup cross sections along with the breakup in the $^{7}\mathrm{Li}+^{124}\mathrm{Sn}$ system. The systematics of one and two neutron stripping and pickup cross sections with a $^{7}\mathrm{Li}$ projectile on several targets show an approximate universal behavior, which has been explained by a simple model based on barrier penetration. Complete reaction mechanism have been studied by comparing the reaction cross sections with the measured total fusion and one neutron transfer cross sections.

Reaction channel contributions to proton scattering at 65 MeV

Background: Well-established coupled channel (CC) and coupled reaction channel (CRC) processes make contributions to elastic scattering that are absent from local density folding models.Purpose: To establish and characterize the contribution to the proton optical model potential (OMP) made by the coupling to neutron pickup channels, in particular the proton OMP for 65 MeV protons on $^{48}\mathrm{Ca}$ and $^{40}\mathrm{Ca}$. Also to relate this contribution to results for ${}^{40}\mathrm{Ca}$ at lower energies; to investigate the dynamical nonlocality of this contribution; to characterize the effect on the OMP of breakup of the deuteron.Methods: CRC calculations of neutron pickup and CC calculations of collective states, provide the elastic channel $S$ matrix ${S}_{lj}$. Inversion of ${S}_{lj}$ produces a local potential that yields, in a single channel calculation, the elastic scattering observables from the CC/CRC calculation. Subtracting the bare potential yields a local and $l$-independent representation of the dynamical polarization potential, DPP. From the DPPs due to a selection of channel couplings the influence of dynamically generated nonlocality can be identified. The effect of coupling to the deuteron breakup continuum is also identified.Results: For $^{40}\mathrm{Ca}$, coupling to pickup channels has an effect on observables somewhat weaker than that at 30 MeV, and much less than for pickup coupling for $^{48}\mathrm{Ca}$. The DPPs have similar general properties in each case, but are much larger in magnitude for $^{48}\mathrm{Ca}$. Subsequent breakup of the deuteron makes a large contribution to the DPP, and hence to the OMP. The formal DPPs due to pickup coupling exhibit dynamical nonlocality.Conclusions: The DPPs challenge local density folding models for elastic scattering. The breakup of the deuteron must henceforth be included in calculations of the DPP due to neutron pickup in proton scattering. Pickup coupling effects are still substantial at 65 MeV. No smoothly varying global OMP could fit proton elastic scattering from both ${}^{40}\mathrm{Ca}$ and ${}^{48}\mathrm{Ca}$.

Reaction channel contributions to the triton optical potential

Background: The well-established coupled channel and coupled reaction channel processes contributing to direct reactions make particular contributions to elastic scattering that are absent from local density folding models. Very little has been established concerning the contribution of these processes to the optical model potentials (OMPs) for 3He scattering. For studying such processes, spin-saturated closed shell nuclei such as 16O and 40Ca are particularly suitable target nuclei and the (3He, 4He) reaction is easily handled within conventional reaction theory because it avoids complications such as breakup. Purpose: To establish and characterize the contribution to the 3He-nucleus interaction generated by coupling to neutron pickup (outgoing 4He) channels; also to study the contribution of collective states and identify effects of dynamical nonlocality from these couplings. Methods: Coupled reaction channel (CRC) calculations, including coupling to collective states, will provide the elastic channel S-matrix Sl j resulting from the included processes. Inversion of Sl j will produce the local potential that yields, in a single channel calculation, the elastic scattering observables from the coupled channel calculation. Subtracting the bare potential from the CRC calculations yields a local and l-independent representation of the dynamical polarization potential (DPP). From the DPPs, because of a range of combinations of channel couplings, the influence of dynamically generated nonlocality can be identified. Results: Coupling to 4He channels systematically induces repulsion and absorption in the 3He OMP and also a reduction in the rms radius of the real part. The repulsion and absorption is less for 208Pb than for the lighter target nuclei although the qualitative effects, including the general undularity of the DPPs, are similar for all cases; therefore coupling to these channels cannot be represented by renormalizing folding model potentials. Evidence is presented for substantial dynamical nonlocality of the induced DPPs; for 40Ca this modifies direct reaction angular distributions. The local equivalent DPPs for individual couplings cannot be added to give the overall DPP for the complete set of couplings. For the 208Pb case, channel coupling reduces the reaction cross section although it increases it for 16O, with 40Ca an intermediate case. Conclusions: The DPPs established here strongly challenge the notion that folding models, in particular local density models, provide a satisfactory description of elastic scattering of 3He from nuclei. Coupling to neutron pickup channels induces dynamical nonlocality in the 3He OMP with implications for direct reactions involving 3He. Departures from a smooth radial form for the 3He OMP should be apparent in good fits to suitable elastic scattering data.

Role of neutron excess in the projectile for the production of heavy neutron-rich nuclei

To shed light on the conditions for synthesizing some new heavy neutron-rich nuclei using multinucleon transfer reactions, the reaction systems $^{40}\mathrm{Ca}+^{208}\mathrm{Pb}$, $^{58}\mathrm{Ni}+^{208}\mathrm{Pb}$, $^{40}\mathrm{Ar}+^{208}\mathrm{Pb}$, $^{64}\mathrm{Ni}+^{208}\mathrm{Pb}$, and $^{136}\mathrm{Xe}+^{208}\mathrm{Pb}$ are investigated within improved dinuclear system (DNS) $\mathrm{model}+$gemini$++$. The transfer cross sections are calculated and compared with existing experimental data. The calculated results are in good agreement with available data. One found the projectiles are changed from the neutron-deficient $^{40}\mathrm{Ca}$ and $^{58}\mathrm{Ni}$ to moderately neutron-rich $^{40}\mathrm{Ar}$, and neutron-rich $^{64}\mathrm{Ni}$ and $^{136}\mathrm{Xe}$ projectiles on $^{208}\mathrm{Pb}$ target, the transfer flux its trend gradually evolves from proton stripping and neutron pickup to the proton pickup and neutron stripping and pickup (pickup and stripping are referring to the projectilelike fragment).

Influence of neutron transfer channels and collective excitations in the fusion of Si28 with Zr90,92,94,96 targets

This work theoretically explores the role of neutron transfer channels and/or collective inelastic surface excitations in the fusion of $^{28}\mathrm{Si}$ with $^{90,92,94,96}\mathrm{Zr}$ targets by using the coupled channel theory and the energy dependent Woods-Saxon potential (EDWSP) model. The series of $^{90,92,94,96}\mathrm{Zr}$ targets is quite interesting due to the fact that the possibilities of neutron transfer channels with positive ground state $Q$ values increase with the increase of isotopic mass. For $^{28}\mathrm{Si}+^{90}\mathrm{Zr}$ reaction, the influences of inelastic surface excitations turned out to be important and coupling of such channels to their relative motion reproduced the experimental data. In the case of $^{28}\mathrm{Si}+^{92}\mathrm{Zr}$ reaction, in addition to consideration of low lying states such as ${2}^{+}$ and ${3}^{\ensuremath{-}}$ vibrational states of colliding nuclei, the coupling to two neutron pickup channels is necessarily required to address the sub-barrier fusion anomalies. For $^{28}\mathrm{Si}+^{94,96}\mathrm{Zr}$ reactions, the inclusions of multiphonon states of type ${2}^{+}$ and ${3}^{\ensuremath{-}}$ of colliding nuclei were not able to reproduce the fusion enhancement particularly at below barrier energies. In this case, neutron transfer channels with positive ground state $Q$ value play a crucial role in the enhancement of fusion cross-section data at sub-barrier energies and therefore must be included in the coupled channel description. In distinction, in the EDWSP model, the energy dependence in the nucleus-nucleus potential causes barrier modification effects and subsequently induces a barrier lowering phenomenon. In this way, the EDWSP based outcomes reasonably address the sub-barrier fusion anomalies of $^{28}\mathrm{Si}+^{90,92,94,96}\mathrm{Zr}$ reactions and thus impacts of dominant intrinsic channels are intrinsically included due to the dynamical nature of the energy dependent interaction potential. For studied systems, the EDWSP outcomes are able to achieve an agreement with the portion of above barrier fusion data within 10% with a probability greater than 90%. Within this model, 33 fusion data points out of 38 fusion data points lie within 5%. Only five fusion data points lie within 10% and thereby the EDWSP model adequately addresses the fusion anomalies of the chosen reactions. The smaller values of ${\ensuremath{\chi}}^{2}$ analysis for the EDWSP calculations, which range from 2.82 to 3.14, indicate that the model predictions appropriately describe the observed fusion dynamics of the studied reactions.

Investigation of the fusion process for B10+Au197 at near-barrier energies

In a previous work, we presented data for the $^{10}\mathrm{B}+^{197}\mathrm{Au}$ system, corresponding to quasielastic and elastic scattering, $^{197}\mathrm{Au}$ inelastic excitation, and one neutron pickup transfer, measuring the angular distribution of scattered beam-like ejectiles at several energies around the Coulomb barrier. In this paper, we present data for the fusion process of the same system, at several energies around the Coulomb barrier, as well as new data for one neutron pickup and stripping transfer. In this case, we detected offline $\ensuremath{\gamma}$ rays stemming from the $\ensuremath{\beta}$-delayed decay chain of fusion-evaporation residues and heavy transfer products. As in our previous work, we analyzed this data set with coupled reaction channels calculations using the S\~ao Paulo potential. We show that the coupling to the one neutron transfer channel is quite important to describe the fusion data at the sub-barrier energy region. We also provide a comparison of the experimental fusion cross sections obtained for $^{10}\mathrm{B}+^{197}\mathrm{Au}$ with data for several other systems involving the same target nucleus.

Reaction channel contributions to the helion optical potential

Background: The well-established coupled channel and coupled reaction channel processes contributing to direct reactions make particular contributions to elastic scattering that are absent from local density folding models. Very little has been established concerning the contribution of these processes to the optical model potentials (OMPs) for $^{3}\mathrm{He}$ scattering. For studying such processes, spin-saturated closed shell nuclei such as $^{16}\mathrm{O}$ and $^{40}\mathrm{Ca}$ are particularly suitable target nuclei and the ($^{3}\mathrm{He}$, $^{4}\mathrm{He}$) reaction is easily handled within conventional reaction theory because it avoids complications such as breakup.Purpose: To establish and characterize the contribution to the $^{3}\mathrm{He}$-nucleus interaction generated by coupling to neutron pickup (outgoing $^{4}\mathrm{He}$) channels; also to study the contribution of collective states and identify effects of dynamical nonlocality from these couplings.Methods: Coupled reaction channel (CRC) calculations, including coupling to collective states, will provide the elastic channel $S$-matrix ${S}_{lj}$ resulting from the included processes. Inversion of ${S}_{lj}$ will produce the local potential that yields, in a single channel calculation, the elastic scattering observables from the coupled channel calculation. Subtracting the bare potential from the CRC calculations yields a local and $l$-independent representation of the dynamical polarization potential (DPP). From the DPPs, because of a range of combinations of channel couplings, the influence of dynamically generated nonlocality can be identified.Results: Coupling to $^{4}\mathrm{He}$ channels systematically induces repulsion and absorption in the $^{3}\mathrm{He}$ OMP and also a reduction in the rms radius of the real part. The repulsion and absorption is less for $^{208}\mathrm{Pb}$ than for the lighter target nuclei although the qualitative effects, including the general undularity of the DPPs, are similar for all cases; therefore coupling to these channels cannot be represented by renormalizing folding model potentials. Evidence is presented for substantial dynamical nonlocality of the induced DPPs; for $^{40}\mathrm{Ca}$ this modifies direct reaction angular distributions. The local equivalent DPPs for individual couplings cannot be added to give the overall DPP for the complete set of couplings. For the $^{208}\mathrm{Pb}$ case, channel coupling reduces the reaction cross section although it increases it for $^{16}\mathrm{O}$, with $^{40}\mathrm{Ca}$ an intermediate case.Conclusions: The DPPs established here strongly challenge the notion that folding models, in particular local density models, provide a satisfactory description of elastic scattering of $^{3}\mathrm{He}$ from nuclei. Coupling to neutron pickup channels induces dynamical nonlocality in the $^{3}\mathrm{He}$ OMP with implications for direct reactions involving $^{3}\mathrm{He}$. Departures from a smooth radial form for the $^{3}\mathrm{He}$ OMP should be apparent in good fits to suitable elastic scattering data.

Multinucleon transfer reactions and proton transfer channels

Transfer reactions have always been of great importance for nuclear structure and reaction mechanism studies. So far, in multinucleon transfer studies, proton pickup channels have been completely identified in atomic and mass numbers at energies close to the Coulomb barrier only in few cases. We measured the multinucleon transfer reactions in the 40Ar+208Pb system near the Coulomb barrier, by employing the PRISMA magnetic spectrometer. By using the most neutron-rich stable 40Ar beam we could populate, besidesneutron pickup and proton stripping channels, also neutron stripping and proton pickup channels. Comparison ofcross sections between different systems with the 208Pb target and with projectiles going from neutron-poor to neutron-rich nuclei, as well as between the data and GRAZING calculations, was carried out.Finally, recent results concerning the measurement of the excitation function from the Coulomb barrier to far below for the 92Mo+54Fe system, where both proton stripping and pickup channels were populated with similar strength, will be discussed.

Neutron pick-up in the 55Mn(d, t)54Mn reaction

In this paper, we analyze the one-neutron pick-up from the 55Mn target when it is bombarded by 17MeV deuteron, by performing coupled reaction channel (CRC) calculations. Spectroscopic amplitudes for CRC calculations, and structural information such as reduced B(E2) transition probabilities, quadrupole, and magnetic momenta, are obtained from shell-model calculations using the fp-kb3 interaction. The calculated structure quantities are in good agreement with the available experimental data for both target and ejectile. Analyses of angular distributions show the relevance of microscopic information for the description of the higher excited states of 54Mn .

Fusion reaction studies for the Li6+Sn124 system at near-barrier energies

The complete and incomplete fusion along with one neutron stripping and pickup cross sections for the $^{6}\mathrm{Li}+^{124}\mathrm{Sn}$ system are measured using online and offline characteristic $\ensuremath{\gamma}$-ray detection techniques. The complete fusion (CF) cross sections at energies above the Coulomb barrier are found to be suppressed by $\ensuremath{\sim}34%$ compared to the coupled channel calculations. This suppression observed in complete fusion cross sections is found to be commensurate with the measured total incomplete fusion (ICF) cross sections. There is a distinct feature observed in the ICF cross sections, i.e., $d$ capture is found to be dominant than $\ensuremath{\alpha}$ capture at all the measured energies, contrary to the data available for $^{6}\mathrm{Li}+^{209}\mathrm{Bi},^{197}\mathrm{Au}$ systems. The total fusion cross section ratio between $^{6}\mathrm{Li}$ and $^{7}\mathrm{Li}$ induced reactions shows an increasing trend as the energy decreases below the barrier while it remains unity at above-barrier energies. A simultaneous explanation of complete, incomplete, and total fusion (TF) data is also obtained from the calculations based on the continuum discretized coupled channel method with short-range imaginary potentials. The cross section ratios of CF/TF and ICF/TF obtained from the data as well as the calculations shows the dominance of ICF at below-barrier energies and CF at above-barrier energies.

Double charge-exchange reactions and the effect of transfer

There is a recently renewed interest on the study of single and double charge exchange reactions with heavy ions. We report here a preliminary theoretical study of double charge exchange reactions in terms of two successive charge exchanges in 2nd order Distorted Wave Born approximation. This allows us to include the effect of the different transfer channels in an approximate way. Evidences show that the charge exchange process is dominant. The following one in importance is the combination of one single charge exchange, one neutron pick-up and one proton stripping. This particular process calls for further investigation.