Distinguished EPJ Referees

EPJ D Highlight - Characterising cold fusion in 2D models

Mapping the probability of fusion

A new 2D modelling approach has been used to directly calculate how hydrogen nuclei fuse into helium after capturing muons

Progress towards ‘cold fusion,’ where nuclear fusion can occur at close to room temperatures, has now been at a standstill for decades. However, an increasing number of studies are now proposing that the reaction could be triggered more easily through a mechanism involving muons – elementary particles with the same charge as electrons, but with around 200 times their mass. Through a study published in EPJ D, researchers led by Francisco Caruso at the Brazilian Centre for Physical Research have shown theoretically how this process would unfold within 2D systems, without any need for approximations.


EPJ D Highlight - Optimising laser-driven electron acceleration

The net energy gain of electrons as a function of time with corresponding electron momentum (centre). E. Molnár, D. Stutman, C. Ticos (2020)

A new paper examines how tuning aspects of a powerful laser beam can affect the acceleration of electrons, attempting to find the recipe for maximum net energy gain.

The interaction between lasers and matter is at the forefront of new investigations into fundamental physics as well as forming a potential bedrock for new technological innovations. One of the initiatives spearheading this investigation is the Extreme Light Infrastructure Nuclear Physics (ELI-NP) project. Here the project’s High-Power Laser System (HPLS) — the world’s most powerful laser—is just one of the tools driving electron acceleration with lasers, Direct Laser Acceleration (DLA). In a new paper published in EPJ D, Etele Molnár, ELI-NP, Bucharest, and co-authors study and review the characteristics of electron acceleration in a vacuum caused by the highest-power laser pulses achievable today looking for the key to maximum net energy gain.


EPJ D Highlight - Identifying biomolecule fragments in ionising radiation

Glycine fragments during heavy ion bombardment. Source

Research published in EPJ D has revealed how the nature of biomolecule fragmentation varies with the energies of electrons produced when living cells are irradiated with heavy ions.

When living cells are bombarded with fast, heavy ions, their interactions with water molecules can produce randomly scattered ‘secondary’ electrons with a wide range of energies. These electrons can then go on to trigger potentially damaging reactions in nearby biological molecules, producing electrically charged fragments. So far, however, researchers have yet to determine the precise energies at which secondary electrons produce certain fragments. In a new study published in EPJ D, researchers in Japan led by Hidetsugu Tsuchida at Kyoto University define for the first time the precise exact ranges in which positively and negatively charged fragments can be produced.


EPJ D Topical review - Confining and compressing the atom

Illustrating the effect of confinement within spheres of different radius on an atomic wavefunction (the example chosen is for Calcium)

A new Review article in EPJD from Jean-Patrick Connerade (Imperial College London and European Academy EASAL Paris) presents a brief introduction to the physics of confined atoms. The subject has acquired importance in the areas of endohedral fullerenes, quantum dots, bubbles in solids (e.g. helium bubbles in the walls of nuclear reactors), atoms trapped in zeolites, impurities in solids, etc. Confining and compressing the atom is considered from the outset as a problem of fundamental atomic physics inherent to basic models such as the Thomas-Fermi and Hartree-Fock approximations to many-electron atoms.


EPJ D Highlight - Slowing light in an optical cavity with mechanical resonators and mirrors

A schematic diagram of the position-dependent mass optomechanical system studied in this work.

Theoretical physicists Kamran Ullah and Hameed Ullah have shown how a position-dependent mass optomechanical system involving a cavity between two mirrors, one attached to a resonator, can enhance induced transparency and reduce the speed of light.

We are all taught at high school that the speed of light through a vacuum is about 300000 km/s, which means that a beam from Earth takes about 2.5 seconds to reach the Moon. It naturally moves more slowly through transparent objects, however, and scientists have found ways to slow it dramatically. Optomechanics, or the interaction of electromagnetic radiation with mechanical systems, is a relatively new and effective way of approaching this. Theoretical physicists Kamran Ullah from Quaid-i-Azam University, Islamabad, Pakistan and Hameed Ullah from the Institute of Physics, Porto Alegre, Brazil have now demonstrated how light is slowed in a position-based mass optomechanical system. This work has been published in EPJ D.


EPJ D Topical review - Crystal-based intensive gamma-ray light sources

In a Topical review just published in EPJD, A.V. Korol and A.V. Solov'yov (MBN Research Center, Germany) discuss possibilities for designing and practical realization of novel intensive gamma-ray Crystal-based LSs (CLS) operating at photon energies from 102 keV and above that can be constructed exposing oriented crystals to beams of ultrarelativistic particles. CLSs can generate radiation in the photon energy range where the technologies based on the fields of permanent magnets become inefficient or incapable.


EPJ D Highlight - Avoiding environmental losses in quantum information systems

Transitioning states in diamond imperfections.

Through new techniques for generating ‘exceptional points’ in quantum information systems, researchers have minimised the transitions through which they lose information to their surrounding environments.

Recently, researchers have begun to exploit the effects of quantum mechanics to process information in some fascinating new ways. One of the main challenges faced by these efforts is that systems can easily lose their quantum information as they interact with particles in their surrounding environments. To understand this behaviour, researchers in the past have used advanced models to observe how systems can spontaneously evolve into different states over time – losing their quantum information in the process. Through new research published in EPJ D, M. Reboiro and colleagues at the University of La Plata in Argentina have discovered how robust initial states can be prepared in quantum information systems, avoiding any unwanted transitions extensive time periods.


EPJ D Colloquium - Simulating lattice gauge theories within quantum technologies

Lattice gauge theories, which originated from particle physics in the context of Quantum Chromodynamics (QCD), provide an important intellectual stimulus to further develop quantum information technologies. While one long-term goal is the reliable quantum simulation of currently intractable aspects of QCD itself, lattice gauge theories also play an important role in condensed matter physics and in quantum information science. In this way, lattice gauge theories provide both motivation and a framework for inter-disciplinary research towards the development of special purpose digital and analog quantum simulators, and ultimately of scalable universal quantum computers.


EPJ D Highlight - Measuring electron emission from irradiated biomolecules

Variations in electron scattering angles

OrigiA new experiment has characterised the properties of the electrons emitted when a key constituent of DNA is bombarded with high-velocity ions.

When fast-moving ions cross paths with large biomolecules, the resulting collisions produce many low-energy electrons which can go on to ionise the molecules even further. To fully understand how biological structures are affected by this radiation, it is important for physicists to measure how electrons are scattered during collisions. So far, however, researchers’ understanding of the process has remained limited. In new research published in EPJ D, researchers in India and Argentina, led by Lokesh Tribedi at the Tata Institute of Fundamental Research, have successfully determined the characteristics of electron emission when high-velocity ions collide with adenine – one of the four key nucleobases of DNA.


EPJ D Topical review - Wigner scattering theory for systems held together by Coulombic forces

Originally developed and formulated for nuclear scattering, Wigner’s theory is extremely general, with application in many branches of physics. Atomic Physics often makes use of an apparently separate formalism (MQDT) which is in fact a specialisation of Wigner’s theory. In a new Topical Review article published in EPJD, Jean-Patrick Connerade (Imperial College London, UK and and European Academy EASAL, France) discusses the relevance of Wigner Scattering theory and in particular its K-matrix formulation for all systems held together by coulombic forces, including not only atoms and molecules but also clusters.


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