Probing transfer to unbound states of the ejectile with weakly boundLi7onNb93

Abstract

The two-step process of transfer followed by breakup is explored by measuring a rather complete set of exclusive data for reaction channels populating states in the ejectile continua of the 7 Li+ 93 Nb system at energies close to the Coulomb barrier. The cross sections for α + α events from one proton pickup were found to be smaller than those for α + d events from one neutron stripping and α + t events from direct breakup of 7 Li. Coupled channels Born approximation and continuum discretized coupled channels calculations describe the data well and support the conclusion that the α + d and α + α events are produced by direct transfer to unbound states of the ejectile.PACS numbers: 25.70. Hi,25.70.Bc,24.10.Eq,25.70.Mn, Exploring the properties of weakly-bound stable/unstable nuclei via transfer reactions is a topic of current interest [1,2] and also a focus of the next generation of high-intensity isotope-separator on-line (ISOL) radioactive ion beam facilities. Due to the low breakup threshold of such nuclei, population of the continuum is probable and consequently a large coupling effect is expected at energies around the Coulomb barrier. This may take place directly through inelastic excitation of the projectile (prompt or resonant breakup) or by nucleon transfer leaving the ejectile in an unbound state (transferbreakup) [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15]. The large positive Q-values for the transfer of neutrons from light neutron-rich projectiles to heavy targets also emphasize the role of neutron evaporation following transfer [16,17]. Exclusive measurements are essential to disentangle these reaction channels. Also, complete measurements of different reaction channels as well as theoretical calculations are required to understand the interplay between them. Among the limited exclusive measurements aimed at studying different breakup processes, very few data on absolute cross sections are available for direct breakup [4][5][6][7][8]13], while for transfer-breakup absolute differential cross sections are only available for the neutron transfer channels at energies close to the Coulomb barrier [5,7].Among the processes discussed above, investigation of the two-step reaction mechanism, viz., one nucleon transfer followed by breakup, is of current interest for the weakly-bound stable nuclei 6,7 Li and 9 Be [5, 9-12, 14, 18]. This complex process needs the simultaneous understanding of both the breakup and transfer reactions. In an earlier measurement of the 7 Li+ 65 Cu system [5] it was observed that 1n-stripping leading to 6 Li in its unbound 3 + 1 excited state is more probable than inelastic excitation of 7 Li to its resonant states. In recent measurements with 7 Li [9, 10], the importance of * sanat@barc.gov.in 1p-pickup over the direct breakup of the projectile was highlighted while explaining the suppression of fusion at energies above the Coulomb barrier. Hence, understanding the mechanism of projectile breakup-whether direct or transfer breakup-is crucial while studying the reaction d...

Exploring contributions from incomplete fusion inLi6,7+Bi209andParkar1, Jha2, Kailas3 2016Phys. Rev. CSelf Cite447591View full textAdd to dashboardCite

“…In the studies with 6 Li on 209 Bi [34] and 159 Tb [35], it is pointed out that the d-ICF cross-sections are much more dominant compared with the transfer cross-sections in inclusive alpha measurements. In recent complete study on transfer induced breakup with 7 Li on 89 Y [36], it is concluded that the transfer induced breakup and noncapture breakup added together can only account for 8 % of inclusive alpha cross-section.…”

Interpretation of coincidence data from strip detectors and extraction of absolute cross section using 3-body Monte Carlo simulation method

“…The accurate knowledge of these parameters are found to be important for the estimation of the accurate response of the detection setup, which is responsible for the proper angular distribution measurements and consequently extraction of the absolute cross sections of the different reaction processes. The extracted cross sections of various breakup processes for 7 Li+ 93 Nb system using the methods discussed in the present paper were published in our earlier paper [9]. The interpretation of the various observables from coincidence measurements has also been presented.…”

Coupled-reaction-channel study of the C12(α,Be8) reaction and the Cuong1, Descouvemont2, Khoa3 et al. 2020Phys. Rev. C3000View full textAdd to dashboardCite

“…Given a well established 2α-cluster structure of the unbound 8 Be nucleus, the 8 Be+ 8 Be interaction potential poses a four-body problem which is a challenge for the determination of the 8 Be+ 8 Be optical potential (OP) that cannot be deduced from a standard optical model (OM) analysis because of the lack of the elastic 8 Be+ 8 Be scattering data. The knowledge about the α+ 8 Be and 8 Be-nucleus OP's should be also important for the studies of those direct reaction processes that produce 8 Be fragments in the exit channel [5][6][7]. Although the α-nucleus and nucleus-nucleus OP's are proven to be well described by the doublefolding model (DFM) using the accurate ground-state densities of the colliding nuclei and a realistic density dependent nucleon-nucleon (NN) interaction (see, e.g., Refs.…”

“…In the recent version of the CDCC theory, the continuum of deuteron is approximated by the square-integrable functions corresponding to positive energies. As a result, this approach can be well extended to study elastic scattering of exotic nuclei that have rather low breakup energies (typical examples are 6 He and 11 Be).…”