Editor in Chief, Michael Thoennessen, celebrates the 50th anniversary of Physical Review A, B, C, and D.

The year 2020 marks Physical Review C’s 50^th anniversary. As part of the celebration, the editors are assembling a collection of milestone papers from PRC that remain central to current developments in nuclear physics.

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A new analysis of heavy-ion collision experiments uncovers evidence that two colliding nuclei behave like a Josephson junction—a device in which Cooper pairs tunnel through a barrier between two superfluids.

Viewpoint on:
G. Potel, F. Barranco, E. Vigezzi, and R. A. Broglia
Phys. Rev. C 103, L021601 (2021)

Neutron star merger ejecta are currently the most viable astrophysical site for $r$-process nucleosynthesis. Fission plays a fundamental role. The manuscript presents an updated scission-point model for fission fragment distributions, which improves agreement with experimental fission yields. Two astrophysical scenarios, based on alternative weak-interaction hypotheses, are employed to reanalyze the role of fission. Regions of the nuclear chart where fission is important are identified, and the impact of fission yields on the final $r$-process abundance distribution is elaborated.

The authors provide a state-of-the-art overview of projection techniques employed in beyond-mean-field many-body methods. They focus on two symmetries that are of critical importance for the description of nuclear spectroscopy, particle number, and angular momentum. The presentation covers formal aspects of symmetry restoration (group theory) and practical aspects related to numerical implementation. A number of illustrative examples are given, including cranked states in odd-$A$ nuclei.

Describing fission as a diffusion process guided by shape-dependent microscopic level densities, the authors address how the available energy at scission is divided into shape distortion and statistical excitation. For the first time, they extract the resulting total fragment kinetic energy for various mass partitions, and study how this observable correlates with the neutron multiplicity. With increasing neutron energy a superlong fission mode appears which drastically changes the observables.

The finite-amplitude method is used in solving the local quasiparticle random-phase approximation to calculate the collective inertia along a fission path obtained by the constrained Hartree-Fock-Bogoliubov method with a Skyrme energy-density functional. The collective inertia obtained for the symmetric fission of ${}^{240}$Pu and ${}^{256}$Fm is considerably larger than that obtained in the cranking approximation. Including such dynamical residual effects leads to an orders of magnitude difference in the half-lives compared to those calculated using the WKB approximation.

These calculations illustrate that hadron production in high-energy central nuclear collisions is described by the recombination of a dense plasma of partons at low transverse momentum while the fragmentation of high-energy jets dominates at high transverse momentum.

V. Greco, C. M. Ko, and P. Lévai
Phys. Rev. C 68, 034904 (2003)

R. J. Fries, B. Müller, C. Nonaka, and S. A. Bass
Phys. Rev. C 68, 044902 (2003)

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γ-ray transitions in nuclei near the proton dripline and for the heaviest elements are identified with unprecedented selectivity.

E. S. Paul, P. J. Woods, T. Davinson, R. D. Page, P. J. Sellin, C. W. Beausang, R. M. Clark, R. A. Cunningham, S. A. Forbes, D. B. Fossan, A. Gizon, J. Gizon, K. Hauschild, I. M. Hibbert, A. N. James, D. R. LaFosse, I. Lazarus, H. Schnare, J. Simpson, R. Wadsworth, and M. P. Waring
Phys. Rev. C 51, 78 (1995)

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Updated antineutrino spectra from nuclear reactors provide a baseline for searches for sterile neutrinos.

Patrick Huber
Phys. Rev. C 84, 024617 (2011)

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APS Editor in Chief, Michael Thoennessen, discusses a new opportunity for communicating authors to include their pronouns together with their contact email in order to promote a more respectful, inclusive, and equitable environment.

With no neutron target available, radiative pion capture by deuterium, employed to obtain a precision measurement of the neutron-neutron scattering length, confirms charge-symmetry breaking in the nucleon-nucleon interaction.

W. R. Gibbs, B. F. Gibson, and G. J. Stephenson, Jr.
Phys. Rev. C 11, 90 (1975)

O. Schori, B. Gabioud, C. Joseph, J. P. Perroud, D. Rüegger, M. T. Tran, P. Truöl, E. Winkelmann, and W. Dahme
Phys. Rev. C 35, 2252 (1987)

Q. Chen, C. R. Howell, T. S. Carman, W. R. Gibbs, B. F. Gibson, A. Hussein, M. R. Kiser, G. Mertens, C. F. Moore, C. Morris, A. Obst, E. Pasyuk, C. D. Roper, F. Salinas, H. R. Setze, I. Slaus, S. Sterbenz, W. Tornow, R. L. Walter, C. R. Whiteley, and M. Whitton
Phys. Rev. C 77, 054002 (2008)

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Researchers look back at key contributions to the field of nuclear physics.

Special Feature in Physics

Two papers revive established techniques with new methods, interactions, and contemporary computational approaches, leading a resurgence in ab initio calculations of light- and medium-mass nuclei.

P. Navrátil, J. P. Vary, and B. R. Barrett
Phys. Rev. C 62, 054311 (2000)

G. Hagen, T. Papenbrock, D. J. Dean, and M. Hjorth-Jensen
Phys. Rev. C 82, 034330 (2010)

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