Physical Review C

High-energy central nuclear collisions create a very high density of quarks and gluons, or partons, which eventually form hadrons. A pair of papers demonstrated that reproducing the data requires different mechanisms which dominate at low versus high transverse momenta. As the system expands and cools, low transverse momentum partons recombine to form hadrons. High transverse momentum partons are much rarer and fragment into hadrons according to perturbative QCD phenomenology. Both processes are a consequence of color confinement.

High-energy central nuclear collisions create a very high density of quarks and gluons, or partons, which eventually form hadrons. A pair of papers demonstrated that reproducing the data requires different mechanisms which dominate at low versus high transverse momenta. As the system expands and cools, low transverse momentum partons recombine to form hadrons. High transverse momentum partons are much rarer and fragment into hadrons according to perturbative QCD phenomenology. Both processes are a consequence of color confinement.

Recoil-mass separators and high-efficiency γ-ray detectors have long been used to correlate fusion-evaporation reaction residues detected in the separator’s focal plane with the γ rays emitted at the target position. However, this is difficult for all but the strongest reaction channels due to backgrounds. The highlighted work pioneered high-resolution recoil-decay tagging, in which an additional tag is provided by the characteristic charged-particle radioactivity of the reaction residue of interest, providing a filter to select the weaker reaction channels. This technique revolutionized nuclear structure studies in exotic and difficult-to-access nuclei near the proton dripline and for the heaviest elements.

Knowledge of electron antineutrino spectra and their uncertainties is crucial for neutrino oscillation investigations and also in searches for new physics beyond the standard model. In light of anomalous results from previous reactor neutrino experiments, this paper provided a critical update of various methods used to extract antineutrino spectra.

Analysis of radiative pion capture by deuterium to obtain the ¹S₀ neutron-neutron scattering length led to definitive experiments at SIN (now PSI) and LAMPF (now LANSCE). The measurement for the 2008 publication produced an uncertainty comparable to that obtained previously for the proton-proton scattering length and confirmed charge-symmetry breaking at the 1% confidence level.

Analysis of radiative pion capture by deuterium to obtain the ¹S₀ neutron-neutron scattering length led to definitive experiments at SIN (now PSI) and LAMPF (now LANSCE). The measurement for the 2008 publication produced an uncertainty comparable to that obtained previously for the proton-proton scattering length and confirmed charge-symmetry breaking at the 1% confidence level.

Analysis of radiative pion capture by deuterium to obtain the ¹S₀ neutron-neutron scattering length led to definitive experiments at SIN (now PSI) and LAMPF (now LANSCE). The measurement for the 2008 publication produced an uncertainty comparable to that obtained previously for the proton-proton scattering length and confirmed charge-symmetry breaking at the 1% confidence level.

Coupled-cluster and configuration-interaction shell model methods originated decades ago. Today, by employing high-precision interactions, new conceptual tools, and powerful computers, these ab initio methods have shown the ability to compute energies and other observables, such as electron scattering form factors, for a wide range of atomic nuclei without adjustable parameters. These two papers were early demonstrations of the power of the revitalized methods.

Coupled-cluster and configuration-interaction shell model methods originated decades ago. Today, by employing high-precision interactions, new conceptual tools, and powerful computers, these ab initio methods have shown the ability to compute energies and other observables, such as electron scattering form factors, for a wide range of atomic nuclei without adjustable parameters. These two papers were early demonstrations of the power of the revitalized methods.

This paper implemented an accurate numerical algorithm for (3+1)-dimensional hydrodynamics to describe high-energy nuclear collisions. The implementation is flexible enough for subsequent incorporation of second-order viscous effects, different equations of state and initial conditions, fluctuations, jet quenching, and more. Even in this initial application, experimental data on rapidity, transverse momentum, and flow coefficients are reproduced well.

Chiral effective field theory (EFT) introduced a systematic, order-by-order prescription for constructing nuclear interactions, including three-body and higher-order forces. Building upon high-quality nucleon-nucleon data, and coupled with advances in many-body methods and computation, chiral EFT sparked a renaissance in low-energy nuclear theory over the past quarter of a century. The influence of effective field theory methods have spread far beyond few-body systems, to descriptions of nuclear collective motion, to weak capture rates, and to dark-matter detection.

Chiral effective field theory (EFT) introduced a systematic, order-by-order prescription for constructing nuclear interactions, including three-body and higher-order forces. Building upon high-quality nucleon-nucleon data, and coupled with advances in many-body methods and computation, chiral EFT sparked a renaissance in low-energy nuclear theory over the past quarter of a century. The influence of effective field theory methods have spread far beyond few-body systems, to descriptions of nuclear collective motion, to weak capture rates, and to dark-matter detection.

Chiral effective field theory (EFT) introduced a systematic, order-by-order prescription for constructing nuclear interactions, including three-body and higher-order forces. Building upon high-quality nucleon-nucleon data, and coupled with advances in many-body methods and computation, chiral EFT sparked a renaissance in low-energy nuclear theory over the past quarter of a century. The influence of effective field theory methods have spread far beyond few-body systems, to descriptions of nuclear collective motion, to weak capture rates, and to dark-matter detection.

Unstable nuclei play a major role in a variety of astrophysical phenomena, from stellar production of neutrinos and γ rays to the creation of the heaviest nuclear species. These papers used radioactive ⁷Be, in one case as the target and in the other as the beam, to study two reactions of importance in astrophysics. These two reactions play a key role in the production of neutrinos in low-mass stars, such as the Sun, and in nucleosynthesis during the CNO-cycle in high-temperature environments.

Unstable nuclei play a major role in a variety of astrophysical phenomena, from stellar production of neutrinos and γ rays to the creation of the heaviest nuclear species. These papers used radioactive ⁷Be, in one case as the target and in the other as the beam, to study two reactions of importance in astrophysics. These two reactions play a key role in the production of neutrinos in low-mass stars, such as the Sun, and in nucleosynthesis during the CNO-cycle in high-temperature environments.

The mass of a nucleus constitutes one of the fundamental nuclear properties. In astrophysics, nuclear masses play a fundamental role in determining the equation of state of neutron stars as well as reaction rates in explosive scenarios such as the r process. These manuscripts constitute two important milestones in the development of fully microscopic models that reproduce known masses with a root-mean-square deviation less than 600 keV.

The mass of a nucleus constitutes one of the fundamental nuclear properties. In astrophysics, nuclear masses play a fundamental role in determining the equation of state of neutron stars as well as reaction rates in explosive scenarios such as the r process. These manuscripts constitute two important milestones in the development of fully microscopic models that reproduce known masses with a root-mean-square deviation less than 600 keV.

Islands of inversion are important regions on the nuclear chart, located in the ocean of short-lived rare isotopes, where nuclear shell structure is markedly different compared to what is observed for stable nuclei. The first indications that neutron number N=20 is not magic in rare isotopes emerged from a mass measurement of neutron-rich sodium isotopes 45 years ago. Shell-model calculations, which bridge large configuration spaces, revealed that this breakdown in magic numbers is due to deformed configurations lowered in energy.

Islands of inversion are important regions on the nuclear chart, located in the ocean of short-lived rare isotopes, where nuclear shell structure is markedly different compared to what is observed for stable nuclei. The first indications that neutron number N=20 is not magic in rare isotopes emerged from a mass measurement of neutron-rich sodium isotopes 45 years ago. Shell-model calculations, which bridge large configuration spaces, revealed that this breakdown in magic numbers is due to deformed configurations lowered in energy.

Since its unexpected discovery in 1938, fission has become the nuclear reaction best known to the public. These two papers illustrate the development of our understanding over 50 years. The first, in 1978, presents the fundamental theory of fission, while the second, in 2017, uses advanced Monte Carlo techniques to trace the shape of the system on its path to the splitting of the nucleus.

Since its unexpected discovery in 1938, fission has become the nuclear reaction best known to the public. These two papers illustrate the development of our understanding over 50 years. The first, in 1978, presents the fundamental theory of fission, while the second, in 2017, uses advanced Monte Carlo techniques to trace the shape of the system on its path to the splitting of the nucleus.

Short-range repulsion is an essential part of the nucleon-nucleon interaction. Although this aspect of the potential should generate short-range correlations among nucleons in a nucleus, direct evidence for it was lacking. The first paper demonstrated that these correlations should be revealed in inelastic electron scattering measurements for a ratio of cross sections of heavy to light nuclei as a function of the Bjorken-x scaling variable by an abrupt change in the slope. The CLAS Collaboration reported the results of measurements that confirmed this idea, clearly showing the onset of the anticipated plateau in the data.

Short-range repulsion is an essential part of the nucleon-nucleon interaction. Although this aspect of the potential should generate short-range correlations among nucleons in a nucleus, direct evidence for it was lacking. The first paper demonstrated that these correlations should be revealed in inelastic electron scattering measurements for a ratio of cross sections of heavy to light nuclei as a function of the Bjorken-x scaling variable by an abrupt change in the slope. The CLAS Collaboration reported the results of measurements that confirmed this idea, clearly showing the onset of the anticipated plateau in the data.

The first of these papers provided a strategy and the techniques for analyzing anisotropic flow in relativistic nuclear collisions. As reported in the second paper, this came to full fruition with measurements by the STAR Collaboration at the BNL Relativistic Heavy Ion Collider five years after it started operation. Nearly all theoretical and experimental researchers in this field are guided by this analysis in investigating the high-temperature matter created in such collisions.

The first of these papers provided a strategy and the techniques for analyzing anisotropic flow in relativistic nuclear collisions. As reported in the second paper, this came to full fruition with measurements by the STAR Collaboration at the BNL Relativistic Heavy Ion Collider five years after it started operation. Nearly all theoretical and experimental researchers in this field are guided by this analysis in investigating the high-temperature matter created in such collisions.

These three papers developed three realistic nuclear potential models—made possible by the Nijmegen partial-wave-analysis data base—whose publications have accumulated more than 5000 citations and which have formed the basis of numerous significant few-body calculations.

These three papers developed three realistic nuclear potential models—made possible by the Nijmegen partial-wave-analysis data base—whose publications have accumulated more than 5000 citations and which have formed the basis of numerous significant few-body calculations.

These three papers developed three realistic nuclear potential models—made possible by the Nijmegen partial-wave-analysis data base—whose publications have accumulated more than 5000 citations and which have formed the basis of numerous significant few-body calculations.

The Nijmegen partial-wave analysis of all NN scattering data below 350 MeV (PWA93) provided the basis for all realistic NN potential models that followed. The χ² per degree of freedom of 1.08 for 3945 degrees of freedom established for the first time the pp and np database and provided extracted energy-dependent phase-shift parameters with realistic errors.

A rare form of radioactivity, in which a proton-laden nucleus decays toward stability via the simultaneous emission of two protons, was observed for ⁴⁸Ni. Using an optical time-projection chamber, the two-proton emission of four ⁴⁸Ni nuclei produced at the National Superconducting Cyclotron Laboratory was captured for the first time on CCD camera, marking a new era of optical detection of sub-atomic charged-particle processes in nuclear physics.

Precise measurements of the β decay between nuclear states of spin-parity 0⁺ and isospin 1 provide fundamental tests of the properties of the electroweak interaction. Collectively, these transitions sensitively probe the conservation of the vector weak current, set tight limits on the presence of scalar currents, and provide the most precise value for $V_{ud}$. The latter result has become a linchpin in the most demanding test of the unitarity of the Cabibbo-Kobayashi-Maskawa (CKM) matrix.

This Jefferson Lab measurement of the ratio of proton elastic electric and magnetic form factors showed a systematic decrease with increasing four-momentum transfer squared Q². These results provided the first definitive evidence for a difference in the distribution of charge and magnetization in the proton.

Calculating the properties of nuclear and neutron matter with realistic strong interactions is notoriously difficult but profoundly important. By using two-nucleon potentials which reproduce nucleon-nucleon scattering data, along with three-body interactions to compute the nuclear equation of state and the corresponding maximum neutron star mass, this pair of papers constituted a basis for major advances in the field.

Calculating the properties of nuclear and neutron matter with realistic strong interactions is notoriously difficult but profoundly important. By using two-nucleon potentials which reproduce nucleon-nucleon scattering data, along with three-body interactions to compute the nuclear equation of state and the corresponding maximum neutron star mass, this pair of papers constituted a basis for major advances in the field.

In the mid-1970’s the SuperHILAC and the Bevatron, built to discover the anti-proton at Lawrence Berkeley Laboratory, were coupled to produce collisions of nuclei at relativistic energies with the goal of studying nuclear matter at high densities. This was the first significant experimental paper in the field of relativistic heavy-ion collisions.

These papers by the SNO Collaboration provided the most precise measurement of the flux of all neutrino flavors (electron, muon, and tau) compared to only electron neutrinos for the high-energy ⁸B solar neutrinos. The experiment showed that the total flux, measured via neutral-current scattering, differs from the electron neutrino flux, measured via charged-current breakup of the deuteron, conclusively demonstrating oscillations of solar neutrinos and therefore that neutrinos cannot be massless. This work led to a Nobel Prize in Physics in 2015.

These papers by the SNO Collaboration provided the most precise measurement of the flux of all neutrino flavors (electron, muon, and tau) compared to only electron neutrinos for the high-energy ⁸B solar neutrinos. The experiment showed that the total flux, measured via neutral-current scattering, differs from the electron neutrino flux, measured via charged-current breakup of the deuteron, conclusively demonstrating oscillations of solar neutrinos and therefore that neutrinos cannot be massless. This work led to a Nobel Prize in Physics in 2015.

Early attempts at a universal model for nuclei failed to simultaneously reproduce both binding energies and radii across the chart of the nuclides. Vautherin and Brink solved this problem by applying the phenomenological, calculation-friendly framework of Skyrme to a range of spherical nuclei, paving the way for decades of similar approaches which are still the go-to method for heavy nuclei today.

This is a foundation paper on the influence of the proton-neutron interaction. It remains of enduring importance in the quest to understand the evolution of shell structure in exotic nuclei, including the breakdown of traditional magic numbers and the appearance of new ones. It has played a seminal role in the description of phenomena such as the appearance of intruder states and the sudden onset of deformation in regions of the nuclear chart such as A ~ 100, 150, and the so-called “island of inversion”. It has spawned extensive experimental studies and is a direct progenitor of theoretical research programs incorporating tensor forces to unravel the trajectories of nuclear magicity and nuclear binding.

This paper presented a pioneering application of Green’s function Monte Carlo (GFMC) methods in nuclear structure physics, which has since fostered three decades of ab-initio calculations with realistic nuclear forces. GFMC research has so far described with precision the observed ground states and low-lying excited states of nuclei with masses up to A=12, the significance of which has been recognized by prestigious awards, such as the APS Bonner Prize and the APS Feshbach Prize.

Superheavy nuclei set limits on the extent of the periodic table of elements and also provide a means of checking nuclear theory. This paper presents results from an experiment, using the reaction pair ⁴⁸Ca and ²⁴⁹Cf, in which the element with atomic number 118 was observed for the first time. This is the heaviest element discovered to date. In November 2016, it was named “oganesson” with the element symbol Og in honor of the lead author of the paper.