2017 Impact factor 2.799
Hadrons and Nuclei

News / Highlights / Colloquium

EPJ A Highlight - The power of resolution in charge-exchange reactions

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Spectra of the 76Ge(3He,t)76As reaction unveiling an enormous number of resolved states at low excitation energies. Five color-coded spectra are stacked on top of each other showing the angular dependences. The isobaric analog state (IAS), GT resonance (GTR) and spin-dipole resonance (SDR) are indicated.

This review highlights the extraordinary power of the hadronic charge-exchange reactions at intermediate energies and at highest spectral resolution, as exemplified by the (n,p)-type (d,2He) and the (p,n)-type (3He,t) reactions. The review shows how areas of nuclear physics, astrophysics and particle physics alike benefit from such enhanced resolution. A major part of this review focuses on weak interaction processes in nuclei, especially on those, where neutrinos play a pivotal role like in solar neutrino induced reactions or in ßß decay. Unexpected and even surprising new features of nuclear structure are being unveiled as a result of high resolution. (See figure).

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EPJ A has a new Editor in Chief for Theoretical Physics II

David Blaschke

From October 2018 David Blaschke succeeds Tamás S. Biró as Editor in Chief of EPJ A for the section Theoretical Physics II: Hadron Physics and Quark Matter.

David Blaschke is Professor for Theoretical Physics of the University of Wroclaw and leading scientist at the Joint Institute for Nuclear Research in Dubna. His research interest is in developing quantum field theoretical models of strongly interacting matter to describe the transition from hadronic matter to the quark gluon plasma in the QCD phase diagram. He studies applications of these models to the physics of compact stars, their mergers and to relativistic heavy-ion collisions.

EPJ A Highlight - Solid deuterium surface degradation at ultracold neutron sources

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Highest intensities of ultracold neutrons (UCN) are in worldwide demand for fundamental physics experiments. Tests of the Standard Model of particle physics and searches for physics beyond it are performed with UCN.

Two of the leading UCN sources, at PSI and at LANL, are based on solid deuterium (sD2) at temperatures around 5 K. Here, together with NCSU they joined forces to understand UCN intensity decreases observed during pulsed neutron production. The study shows that the decrease can be completely explained by the build-up of frost on the sD2 surface during operation. Pulsed proton beams hitting the spallation targets generate heat pulses causing cycles of D2 sublimation and subsequent resublimation on the sD2 surface. Even very small frost flakes can act as total reflectors for UCN and cause an intensity decrease.

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EPJ A Highlight - The Soreq Applied Research Accelerator Facility (SARAF)

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Layout of SARAF, including the accelerator and the research areas.

The Soreq Applied Research Accelerator Facility (SARAF) is under construction in the Soreq Nuclear Research Center at Yavne, Israel. Phase I of SARAF (SARAF-I) is already in operation, generating scientific results in several fields of interest, especially the astrophysical s-process. When completed at the beginning of the next decade, SARAF-II will be a user facility for basic and applied nuclear physics, based on a 40 MeV, 5 mA CW proton/deuteron superconducting linear accelerator. This review presents first a technical overview of SARAF-I and II, including a description of the accelerator and its irradiation targets, and provides a survey of existing research programs at SARAF-I. It then describes in some detail the research potential at the completed facility. SARAF-II’s cutting-edge specifications, with its unique liquid lithium target technology, will enable world-competitive research plans in several disciplines: precision studies of beyond-Standard-Model effects by trapping light exotic radioisotopes (including meaningful studies already at SARAF-I); extended nuclear astrophysics research with higher-energy neutrons, including generation and studies of exotic neutron-rich isotopes relevant to the astrophysical r-process; nuclear structure of exotic isotopes; high-energy neutron cross sections for basic nuclear physics and material science research, including neutron-induced radiation damage; neutron-based imaging with an imaging plane flux similar to that of a 5 MW research reactor; accelerator-based neutron therapy; and, last but not least, novel radiopharmaceuticals development and production.

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EPJ A Highlight - Unresolved puzzles in exotic nuclei

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Closed points are matter radii extracted from experiments for isotopes of Helium (diamonds), Lithium (squares), and Beryllium (triangles).

A new review highlights the historical developments in our understanding of the nuclear structure of unstable and unbound forms of helium, lithium and beryllium

Research into the origin of elements is still of great interest. Many unstable atomic nuclei live long enough to be able to serve as targets for further nuclear reactions - especially in hot environments like the interior of stars. And some of the research with exotic nuclei is, for instance, related to nuclear astrophysics. In this review published in EPJ A, Terry Fortune from the University of Pennsylvania, in Philadelphia, USA, discusses the structure of unstable and unbound forms of Helium, Lithium, and Beryllium nuclei that have unusually large neutron to proton ratios - dubbed ‘exotic’ light nuclei. The author offers an account of historical milestones in measurements and the interpretation of results pertaining to these nuclei.

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EPJ A - New Structure of the Editorial Board and Editor-in-Chief Appointments

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Editorial Board Meeting Heidelberg 2017

EPJ is pleased to announce significant changes concerning the editorial structure of EPJ A. Following the continuous growth and broadening of the journal’s scope over the past few years, the theory section has now been divided into Theory I (Nuclear Physics) and Theory II (Hadron Physics and Quark Matter). Theory I is headed by Prof. Thomas Duguet, who has been newly appointed for this position, while Theory II continues to be headed by Prof. Tamás Biró. Further, and with immediate effect, Prof. Maria Jose Garcia Borge has been appointed Editor-in-Chief for the Experimental Physics section of the journal.

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EPJ A Highlight - From experiment to evaluation, the case of n+238U

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Evaluated nuclear data represent the bridge between experimental and theoretical achievements and final user applications. The complex evolution from experimental data towards final data libraries forms the cornerstone of any evaluation process. Since more than 90% of the fuel in most nuclear power reactors consists of 238U, the respective neutron induced cross sections are of primary importance towards accurate neutron transport calculations. Despite this significance, the relevant experimental data for the 238U(n,γ) capture reaction have only recently provided for a consistent description of the resonance region. In this work, the 238U(n,γ) average cross sections were evaluated in the energy region 5-150 keV, based on recommendations by the IAEA Neutron Standards projects and experimental data not included in previous evaluations.

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EPJ A Highlight - Nuclear and Quark Matter at High Temperature

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Left: sample spectral densities, Right: the resulting scaled energy densities.

In high-temperature field theory applied to nuclear physics, in particular to relativistic heavy-ion collisions, it is a longstanding question how hadrons precisely transform into a quark-gluon matter and back. The change in the effective number of degrees of freedom is rather gradual than sudden, despite the identification of a single deconfinement temperature. In order to gain an insight into this issue while considering the structure of the QGP we review the spectral function approach and its main consequences for the medium properties, including the shear viscosity. The figure plots a sample spectral density on the left and the effective number of degrees of freedom (energy density relative to the free Boltzmann gas) to the right. Two thin spectral lines result in a doubled Stefan-Boltzmann limit (SB), while any finite width reduces the result down to a single SB. When spectral lines become wide, their individual contributions to energy density and pressure drops. Continuum parts have negligible contribution. This causes the melting of hadrons like butter melts in the Sun, with no latent heat in this process.

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EPJ A Highlight - Wavy energy potential patterns from scattering nuclei reveal hidden information

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A feynman diagram of proton-neutron scattering mediated by a neutral pion.

New approach to analysing anomalies in collisions between atomic nuclei promises a new perspective on how they interact

Anomalies always catch the eye. They stand out from an otherwise well-understood order. Anomalies also occur at sub-atomic scale, as nuclei collide and scatter off into each other—an approach used to explore the properties of atomic nuclei. The most basic kind of scattering is called ‘elastic scattering,’ in which interacting particles emerge in the same state after they collide. Although we have the most precise experimental data about this type of scattering, Raymond Mackintosh from the Open University, UK, contends in a paper published in EPJ A that a new approach to analysing such data harbours potential new interpretations of fundamental information about atomic nuclei.

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EPJ A Highlight - Open refereed paper reveals how to study unstable radioactive nuclei’s dual traits

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HIE-ISOLDE production yields.

HIE-ISOLDE acceleration of radioactive beams to peer into the dual state of matter unique to nuclei

Radioactive nuclides, found within an atom's core, all share a common feature: they have too many or too few neutrons to be stable. In a new review published in EPJ A, Maria Jose Borges and Karsten Riisager explain how overcoming technical difficulties in accelerating such radioactive nuclei beams can help push back the boundaries of nuclear physics research. This fascinating topic is the first EPJ A paper to be subjected to an open referee process, whereby the referee's comments are included.

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Editors-in-Chief
David Blaschke, Thomas Duguet and Maria Jose Garcia Borge
Let me say that I am deeply impressed by your professionality -- very much appreciated.

Dieter Frekers, Institute for Nuclear Physics, University of Muenster, Germany

ISSN (Print Edition): 1434-6001
ISSN (Electronic Edition): 1434-601X

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