Weakly bound Nuclei

The development of radioactive beam facilities makes possible the study of weakly bound nuclei far from stability and close to the drip lines. A vast variety of nuclei is now available, therefore a new research ground is open for the discovery of phenomena previously unexpected. Complementary studies with stable weakly bound nuclei can assist such studies. Examples for $^6$He and $^6$Li are discussed.

Unnuclear physics: Conformal symmetry in nuclear reactions

We investigate a nonrelativistic version of Georgi’s “unparticle physics.” We define the unnucleus as a field in a nonrelativistic conformal field theory. Such a field is characterized by a mass and a conformal dimension. We then consider the formal problem of scatterings to a final state consisting of a particle and an unnucleus and show that the differential cross-section, as a function of the recoil energy received by the particle, has a power-law singularity near the maximal recoil energy, where the power is determined by the conformal dimension of the unnucleus. We argue that unlike the relativistic unparticle, which remains a hypothetical object, the unnucleus is realized, to a good approximation, in nuclear reactions involving emission of a few neutrons, when the energy of the final-state neutrons in their center-of-mass frame lies in the range between about 0.1 MeV and 5 MeV. Combining this observation with the known universal properties of fermions at unitarity in a harmonic trap, we predict a power-law behavior of an inclusive cross-section in this kinematic regime. We verify our predictions with previous effective field theory and model calculations of the 6He(p,pα)2n, 3H(π−,γ)3n, and 3H(μ−,νμ)3n reactions and discuss opportunities to measure unnuclei at radioactive beam facilities.

High-resolution radioactive beam study of the $$^{26}\hbox {Al}(d,p$$) reaction and measurements of single-particle spectroscopic factors

We present a detailed comparison of shell model calculations with inverse kinematic transfer reaction data, obtained using a radioactive beam. Experimentally extracted spectroscopic factors from the $$^{26}\hbox {Al}(d,p)^{27}\hbox {Al}$$26Al(d,p)27Al reaction for both even and odd parity states are found to be exceptionally well reproduced by the shell model and a high level of consistency is observed between bound isobaric analog states in $$^{27}\hbox {Al}$$27Al and $$^{27}\hbox {Si}$$27Si, populated via (d, p) and (d, n) transfer, respectively. Furthermore, an evaluation of key resonances in the astrophysical $$^{26}\hbox {Al}(p,\gamma )^{27}\hbox {Si}$$26Al(p,γ)27Si reaction indicates that shell model calculations provide relatively accurate predictions for the existence of strong resonances and mirror nucleus comparisons appear to hold exceptionally well for proton-unbound levels. Consequently, we expect that the utilization of both techniques will likely be a very effective tool in the investigation of stellar processes outside the current reach of experiment.

Probing the 17F+p potential by means of elastic scattering at near barrier energies

Results from the first stage of analysis of the recently performed 17F+p experiment are presented. The experiment was performed at the EXOTIC facility of Legnaro National Laboratory (Italy, LNL-INFN), where the 17F radioactive beam is available. The measurement of elastic scattering angular distributions, in a wide angular range (θcm=20-160 deg) was taken over in order to probe the potential at two near barrier energies, namely: 3.5 AMeV and 4.3 AMeV. The present work, should be considered as the starting point of a general survey along drip line nuclei, aiming to a better understanding and mapping of the nuclear potential at near barrier energies.