Conveners
Nuclear Reactions I: NR 1
- Greg Christian (St Mary's University)
Nuclear Reactions I: NR 3
- Alexandra Gade (Facility for Rare Isotope Beams)
Nuclear Reactions I: NR 5
- Benjamin Kay (Argonne National Laboratory)
Nuclear Reactions I: NR 7
- Daniel Bazin (Michigan State University)
Nuclear Reactions I: NR 9
- Jutta Escher (Lawrence Livermore National Laboratory)
Nuclear Reactions I: NR 11
- Kazuyuki Ogata (Kyushu University)
Nuclear Reactions I: NR 13
- Chris Ruiz (TRIUMF)
The solenoidal-spectrometer technique for direct-reaction studies has advanced significantly since it was first demonstrated with the HELIOS spectrometer at Argonne's ATLAS facility and has become an essential tool for nuclear structure, reaction mechanism, and nuclear astrophysics studies. There are now three dedicated solenoidal spectrometers: the ISOLDE Solenoidal Spectrometer at...
The Facility for Rare Isotope Beams (FRIB) [1] is currently providing primary beams of up to 300 MeV/u (most mid-mass beams are available at about 250 MeV/u) at 10 kW beam power. With this new facility and as the beam power is increased, FRIB is poised to provide access to a wide range of rare isotope beams. In this contribution, the initial results of the observation of new isotopes at FRIB...
The advancement of production techniques to access unstable nuclei far from the stability line has resulted in the discovery of many exotic nuclei characterized by short half-lives and an unusual neutron-to-proton ratio. Such nuclei are of particular interest in fundamental and applied physics. For instance, measurement of interaction ($\sigma_{I}$) and charge-changing cross sections are...
Since nuclear matter is composed of two Fermi particles, protons and neutrons, the equation of state of nuclear matter has a term that depends on the density difference between the two, which is called the symmetry energy. From previous studies, it is known that the first-order density dependence of the symmetry energy is closely related to the thickness of the neutron skin [1].
In this...
The dynamical intranuclear cascade model INCL[1] has been improved by including short-range nucleon-nucleon correlations (SRCs), which are mainly dominated by the formation of np pairs. This new development allows us to obtain a better description of peripheral collisions involving the knockout of a few nucleons in spallation and fragmentation reactions. The new version of our dynamical model...
Various information on the nuclear structure is imprinted on the density profiles, especially, near the nuclear surface. The total reaction cross section of medium- to high-energy nuclear collision has been a standard observable to extract the nuclear radius of unstable nuclei. As higher order information of the nuclear density profile, evaluating a surface diffuseness of the nuclear density...
Simultaneous analyses are performed for cross section data of elastic scattering, Coulomb breakup, transfer and other direct yields for the $d$+$^{197}$Au system at all available energies. The data are reproduced well by the optical model using bare and dynamical polarization potentials. This method of calculation can be successfully applied to the reactions of deuteron with with heavy targets.
Exploring neutron-rich nuclei near the drip-line with significant N/Z asymmetry exposes exotic phenomena like the existence of neutron halo or skin and (dis)appearance of existing magic numbers. Nuclear halos result from spatial distribution of outermost neutrons, causing a low-density extended neutron surface and a notable increase in matter radius. A systematic study of the point proton...
The Borromean structure of the dripline nucleus ${}^{19}$B has garnered the attention of theories and experiments. The enigma is whether the structure of ${}^{19}$B is '${}^{15}$B core + 4$n$' or '${}^{17}$B core + 2$n$'. The point proton radius ($R_p$) is an ideal measure for probing the structure of the nucleus. Further, a combined knowledge of $R_p$ and the point matter radius enables us to...
Obtaining reliable data for nuclear reactions on unstable isotopes remains an important task and a formidable challenge. Cross sections for neutron-induced reactions are particularly elusive, as both projectile and target are unstable. Various indirect methods have been proposed to address this problem. The 'surrogate reaction method' [1] uses inelastic scattering or transfer ('surrogate')...
The ratio [1,2] is a new reaction observable suggested to extract accurately structural information on halo nuclei. It is based on the Recoil Excitation Breakup (REB) model [3], which predicts that taking the ratio of angular distributions for breakup and scattering, the uncertainty related to the reaction dynamics is strongly reduced [1,2]. It exhibits a much better accuracy than traditional...
Determining the equation of state (EoS) for nuclear matter is essential in order to understand the macroscopic properties of nuclear matter in equilibrium states in both finite systems (nuclei) and infinite systems (neutron stars). The purpose of this study is to derive the density-dependent parameter L of the symmetry-energy term of the EoS from the isotope dependence of neutron skin...
The projectile fragmentation reaction is crucial in experimental studies that use radioactive nuclear beams. The isotropic momentum ($P$) distribution of produced fragments, which is observed at relativistic energies, is reasonably explained by a simple model based on the Fermi motion of nucleons in a projectile [1]. At lower energies around 100 MeV/nucleon, the contribution of reaction...
The isospin character of the p-n pair at large relative momentum has been observed for the first time in the 16O ground state. We have measured the 16O(p,dp) and 16O(p,dn) cross sections for the neutron pick-up domain with 392 MeV incident proton at RCNP. The outgoing deuteron was momentum analyzed by the high-resolution spectrometer GrandRAIDEN. Recoiled nucleons N [p or n] were measured by...
In this presentation, I will discuss recent advancements in understanding the electric response of stable nuclei through the inelastic scattering of protons, utilizing the high-resolution Grand Raiden spectrometer. Our study focuses on several key phenomena, including the excitation of giant and pygmy dipole resonances, the electric dipole polarizability of nuclei, and the gamma-decay of giant...
The existence of a superconducting phase associated with the breaking of particle number conservation, has been first identified in metals in the context of the BCS theory. It was realized very soon that the underlying mechanism, connected with pairing correlations at work in the formation of Cooper pairs, bore great generality and was expected to be relevant for a large variety of fermionic...
The anomalies in the electron-positron angular correlations from high-energy decays of 8Be were interpreted by the ATOMKI collaboration as evidence of a new beyond-the-Standard Model boson. A theoretical understanding of the nuclear physics involved is an important step towards verification of this claim. Hence, we investigate proton capture with the ab initio no-core shell model with...
Neutron stars represent the only known place in the universe where neutrons are held in close proximity. This unique scenario results from the extreme gravitational forces that compress them together in nearly pure neutron matter. However, the existence of an isolated multi-neutron system is still an open question.
Theoretical predictions have long suggested the existence of an exotic...
Transfer reactions in inverse kinematics established itself as a very powerful tool to study nuclear structure, addressing many crucial aspects of nuclear structure such as shell evolution, isospin symmetry or physics of unbound states. In 2018, a fruitful experimental campaign took place at the GANIL facility, where the LISE spectrometer was used to produce radioactive beams for two transfer...
The isospin dependence of the thermometric characteristics is investigated in the reactions 78Kr+40Ca and 86Kr+48Ca at 10 AMeV [1,2,3]. These reactions were realized in the context of the ISODEC experiment, performed at Laboratori Nazionali del Sud in Catania, by using the 4π multi-detector CHIMERA [4,5]. The results of the data analysis suggest that the temperature depends on the N/Z ratio....
Large α production cross sections are observed in the reactions involving stable weakly bound (6,7Li, 9Be) projectiles due to α+x cluster structure. In the case of 9Be, as the neutron separation energy is low, the neutron transfer cross sections are dominant. There are few energy correlation studies performed using charged particle coincidences with 9Be projectile. However, angular...
Nuclear reactions are an essential probe into isotope structure and nuclear astrophysics. They are important to learn about where nuclei come from and how they are produced.They provide critical knowledge on how neutrons and protons organize themselves to form matter as we know it and at the limits of stability.
However until recently, models for nuclear reactions included no uncertainty...
A quantitative description of the single-particle configurations of the low-lying states in $^{12}$Be still eludes us despite numerous attempts via direct and indirect reactions. For the three previous (d,p) reactions, their reaction energies and angular coverage were not optimized so the data could not be easily interpreted in terms of well-tested reaction mechanisms. For another, these...
Over the past decade our group has studied the continuum structure of p-rich light nuclei using the invariant-mass technique. This effort has led to the discovery of 7 new isotopes beyond the proton-drip line. Just as important are the findings of new resonances in previously known nuclei and parameter refinement of previously known resonances. Some of the more interesting results (e.g....
The $^3$He$(\alpha,\gamma)^7$Be reaction is an important part of ongoing processes occurring in stars like our very own sun. In the fusion reaction network of the sun, the $^3$He$(\alpha,\gamma)^7$Be reaction is key to determining the $^7$Be and $^8$B neutrino fluxes resulting from the pp-II chain . In standard solar model (SSM) predictions of these neutrino fluxes, the low-energy...
By exploiting the near-perfect symplectic symmetry that emerges from the strong interaction, the symmetry-adapted no-core shell model provides a robust ab initio description of the nucleus capable of accurately capturing challenging collective correlations and clustering features [1,2,3]. Utilizing realistic nucleon-nucleon interactions within this framework allows for a completely *ab...
I will review our recent activities on breakup and knockout reactions. The following topics will be covered:
1) New reaction model for describing knockout reactions for fragile/unbound particles,
2) Effective polarization of the reaction residue of alpha knockout reactions.
3) Description of high-energy transfer reactions with the impulse approximation.
4) Semiclassical distorted wave...
Departures from the conventional liquid-drop-like saturated density of the nucleus represent a key interest in the study of nuclear structure. Phenomena of such as bubble structures offer a unique insight into the macroscopic effects of the nuclear interaction.
We present experimental indication of the occurrence of this phenomenon in $^{46}$Ar, where the depletion is generated by the level...
Nucleon-nucleus optical-model potentials are an effective model to characterize the nuclear interaction. They are an essential input for nuclear reaction calculations required in nuclear physics, astrophysics, cosmology, and engineering applications. Proper uncertainty quantification of the optical model is necessary to obtain reliable uncertainties on extrapolations and on any result using...
