Explore the vast range of titles available.

We describe a laser–plasma platform for photon–photon collision experiments to measure fundamental quantum electrodynamic processes. As an example we describe using this platform to attempt to observe the linear Breit–Wheeler process. The platform has been developed using the Gemini laser facility at the Rutherford Appleton Laboratory. A laser Wakefield accelerator and a bremsstrahlung convertor are used to generate a collimated beam of photons with energies of hundreds of MeV, that collide with keV x-ray photons generated by a laser heated plasma target. To detect the pairs generated by the photon–photon collisions, a magnetic transport system has been developed which directs the pairs onto scintillation-based and hybrid silicon pixel single particle detectors (SPDs). We present commissioning results from an experimental campaign using this laser–plasma platform for photon–photon physics, demonstrating successful generation of both photon sources, characterisation of the magnetic transport system and calibration of the SPDs, and discuss the feasibility of this platform for the observation of the Breit–Wheeler process. The design of the platform will also serve as the basis for the investigation of strong-field quantum electrodynamic processes such as the nonlinear Breit–Wheeler and the Trident process, or eventually, photon–photon scattering.

The study of images begins to flourish because of the ubiquity of visual representations in communication. A visual medium communicates across ages and languages. Each artifact, like strokes, colours and gestures, has its specific meaning that highlights human behaviour. In stories, animals in human form delight and capture the audiences’ attention. The selection of animals and their projected ways reflects more than what is expressed directly in the text. As a result, anthropomorphism (nonhuman entities that talk and act like human) is widely used as a communicative tool to insist on sensitive themes. Simultaneously, there is a belief that anthropomorphism misattributed human-like abilities to nonhuman which can risk the people’s approach towards nonhuman. This paper identifies some of the degrees of anthropomorphism noted in Indian visual narratives from Malik’s Munnu: A Boy from Kashmir, Gupta and Rastogi’s Chhotu: A Tale of Partition and Love, Amar Chitra Katha’s Animal Tales from India, Samhita Arni’s Sita’s Ramayana, Amruta Patil’s Aranyaka: Book of the Forest and Samit Basu’s Tall Tales of Vishnu Sharma: Panchatantra. The study researches the role and importance of anthropomorphism in visual narratives.

Modern high-power lasers can generate extreme states of matter that are relevant to astrophysics 1 , equation-of-state studies 2 and fusion energy research 3 , 4 . Laser-driven implosions of spherical polymer shells have, for example, achieved an increase in density of 1,000 times relative to the solid state 5 . These densities are large enough to enable controlled fusion, but to achieve energy gain a small volume of compressed fuel (known as the ‘spark’) must be heated to temperatures of about 10 8  K (corresponding to thermal energies in excess of 10 keV). In the conventional approach to controlled fusion, the spark is both produced and heated by accurately timed shock waves 4 , but this process requires both precise implosion symmetry and a very large drive energy. In principle, these requirements can be significantly relaxed by performing the compression and fast heating separately 6 , 7 , 8 , 9 , 10 ; however, this ‘fast ignitor’ approach 7 also suffers drawbacks, such as propagation losses and deflection of the ultra-intense laser pulse by the plasma surrounding the compressed fuel. Here we employ a new compression geometry that eliminates these problems; we combine production of compressed matter in a laser-driven implosion with picosecond-fast heating by a laser pulse timed to coincide with the peak compression. Our approach therefore permits efficient compression and heating to be carried out simultaneously, providing a route to efficient fusion energy production.

In today’s ocular-centric era, vision and visuality play a significant role in representing ideas. This article analyses anthropomorphism as a communicative mode that helps readers comprehend a story’s underlying meaning, using a socio-semiotics metafunction as a lens. The study focuses on Samit Basu and Ashish Padlekar’s adaptation of the famous Panchatantra collection, The Tall Tales of Vishnu Sharma: Panchatantra (published in 2015), where creatures with the ability to speak are the central characters. This story emphasises a diverse group of characters from the world of Panchatantra who communicate their problems to Vishnu Sharma, their chosen guardian, through the transformation of animals into humans. Through the use of animated letters, mascots, and anthropomorphic parameters, barriers can be eliminated in a creative approach. The paper underscores the significance of studying signs and interpreting visually represented social phenomena in order to articulate culture, society, and historical context. The research is divided into two sections: the first section explores the function of images by analysing image artefacts that question the presence of anthropomorphism. In contrast, the second section introduces the four degrees of anthropomorphism and their characteristics. The hypothesis posits that anthropomorphism can effectively convey meaning, especially in stories aimed at children. This study seeks to contribute to a greater comprehension of the use of anthropomorphism as a creative mode of communication in contemporary literature.

A linear Breit-Wheeler module for the code geant4 has been developed. This allows signal-to-noise ratio calculations of linear Breit-Wheeler detection experiments to be performed within a single framework. The interaction between two photon sources is modeled by treating one as a static field, then photons from the second source are sampled and tracked through the field. To increase the efficiency of the module, we have used a Gaussian process regression, which can lead to an increase in the calculation rate by a factor of up to 1000. To demonstrate the capabilities of this module, we use it to perform a parameter scan, modeling an experiment based on that recently reported by Kettle et al. [New J. Phys. 23, 115006 (2021)]. We show that colliding 50-fs durationγrays, produced through bremsstrahlung emission of a 100 pC, 2-GeV laser wakefield accelerator beam, with a 50-ps x-ray field, generated by a germanium burn-through foil heated to temperatures>150eV, this experiment is capable of producing>1Breit-Wheeler pair per shot.

A new ‘photon–photon collider’, which may enable elusive Breit–Wheeler pair production in an optics laboratory setting, is predicted. Using this concept, it is potentially possible to produce 10 5 Breit–Wheeler electron–positron pairs by firing a gamma-ray beam into a high-temperature radiation field of a laser-heated hohlraum cavity. The ability to create matter from light is amongst the most striking predictions of quantum electrodynamics. Experimental signatures of this have been reported in the scattering of ultra-relativistic electron beams with laser beams 1 , 2 , intense laser–plasma interactions 3 and laser-driven solid target scattering 4 . However, all such routes involve massive particles. The simplest mechanism by which pure light can be transformed into matter, Breit–Wheeler pair production (γγ′ →  e + e − ) 5 , has never been observed in the laboratory. Here, we present the design of a new class of photon–photon collider in which a gamma-ray beam is fired into the high-temperature radiation field of a laser-heated hohlraum. Matching experimental parameters to current-generation facilities, Monte Carlo simulations suggest that this scheme is capable of producing of the order of 10 5 Breit–Wheeler pairs in a single shot. This would provide the first realization of a pure photon–photon collider, representing the advent of a new type of high-energy physics experiment.

The BXSB mouse strain is an important model of glomerulonephritis observed in systemic lupus erythematosus (SLE). Linkage studies have successfully identified disease-susceptibility intervals; however, extracting the identity of the susceptibility gene(s) in such regions is the crucial next step. Congenic mouse strains present a defined genetic resource that is highly amenable to microarray analysis. We have performed microarray analysis using a series of chromosome 1 BXSB congenic mice with partially overlapping disease-susceptibility intervals. Simultaneous comparison of the four congenic lines allowed the identification of expression differences associated with both the initiation and progression of disease. Thus, we have identified a number of novel SLE disease gene candidates and have confirmed the identity of Ifi202 as a disease candidate in the BXSB strain. Sequencing of the promoter regions of Gas5 has revealed polymorphisms in the BXSB strain, which may account for the differential expression profile. Furthermore, the combination of the microarray results with the different phenotypes of these mice has allowed the identification of a number of expression differences that do not necessarily map to the congenic interval, but may be implicated in disease pathways.

Considerable progress towards the achievement of thermonuclear burn using inertial confinement fusion has been achieved at the National Ignition Facility in the USA in the last few years. Other drivers, such as the Z-machine at Sandia, are also making progress towards this goal. A burning thermonuclear plasma would provide a unique and extreme plasma environment; in this paper we discuss (a) different theoretical challenges involved in modelling burning plasmas not currently considered, (b) the use of novel machine learning-based methods that might help large facilities reach ignition, and (c) the connections that a burning plasma might have to fundamental physics, including quantum electrodynamics studies, and the replication and exploration of conditions that last occurred in the first few minutes after the Big Bang. This article is part of a discussion meeting issue ‘Prospects for high gain inertial fusion energy (part 1)’.

High-intensity lasers can be used to generate shockwaves, which have found applications in nuclear fusion, proton imaging, cancer therapies and materials science. Collisionless electrostatic shocks are one type of shockwave widely studied for applications involving ion acceleration. Here we show a novel mechanism for collisionless electrostatic shocks to heat small amounts of solid density matter to temperatures of ∼keV in tens of femtoseconds. Unusually, electrons play no direct role in the heating and it is the ions that determine the heating rate. Ions are heated due to an interplay between the electric field of the shock, the local density increase during the passage of the shock and collisions between different species of ion. In simulations, these factors combine to produce rapid, localized heating of the lighter ion species. Although the heated volume is modest, this would be one of the fastest heating mechanisms discovered if demonstrated in the laboratory. Short pulses of high intensity laser light usually heat the ions in dense plasmas indirectly via collisions with the electrons. Here, the authors identify an extremely rapid alternative heating mechanism based on ion-ion collisions.