Searcharxiv⌕ Search

arXiv subjects

A. Arefiev

Publications and source records attributed to A. Arefiev.

16 recordsLinked to original sources
arXiv2026

CMA-Unfold A Covariance Matrix Adaptation unfolding algorithm for stacked calorimeter detectors

Stacking calorimeters also refered as bremsstrahlung cannons widely used in inertial confinement fusion and ultra-intense laser plasma experiments have become essential diagnostics for characterizing short bursts of high-energy photons and charged particles. Extracting the underlying energy spectrum from these detectors requires solving an ill-posed inverse problem, often complicated by noise, secondary particle contamination, and uncertainties in the detector response. In this work, we introduce an open-source unfolding framework available under the username ggfauvel under CMA-unfold based on the Covariance Matrix Adaptation Evolution Strategy (CMA-ES), designed to reconstruct photon spectra directly from depth-dose profiles without imposing restrictive parametric assumptions. The algorithm demonstrates high robustness, accurately recovering complex spectral shapes while tolerating percent-level deviations in individual detector layers. This approach provides a flexible and noise-resilient tool for the analysis of stacking calorimeter data, with particular relevance for bremsstrahlung diagnostics in inertial confinement fusion and high-intensity laser applications.

physics.plasm-ph↗
arXiv2026

Phase-controlled direct laser acceleration enabled by longitudinal variation of the laser-driven quasi-static plasma magnetic field

Direct laser acceleration (DLA) enables energy transfer from an ultra-high-intensity laser to plasma electrons and underpins many laser-driven particle and radiation-source concepts. A laser-driven azimuthal plasma magnetic field is a key player in this process: it confines energetic electrons, induces betatron oscillations, and makes possible a resonant interaction between the betatron motion and the laser field. While this betatron resonance can enhance electron energy gain, the gain itself generally drives frequency detuning and promotes largely reversible energy exchange that limits net acceleration. Here we show, using a test-electron model with prescribed fields, that a slow longitudinal increase of the quasi-static plasma magnetic field qualitatively changes DLA by introducing hysteresis in the ratio of the betatron frequency to the laser frequency experienced by the electron, so that this ratio depends on the prior evolution of the electron even at the same energy. This hysteresis enables phase control of the electron-laser energy exchange and suppresses the usual reversibility of DLA, allowing electrons to retain the acquired energy and sustain energy gain without intermittent losses.

physics.plasm-ph↗
arXiv2025

Generation of ultrahigh field by micro-bubble implosion

Breaking the 100-MeV barrier for proton acceleration will help elucidate fundamental physics and advance practical applications from inertial confinement fusion to tumour therapy. Herein we propose a novel concept of bubble implosions. A bubble implosion combines micro-bubbles and ultraintense laser pulses of 10^20-10^22W/cm^2 to generate ultrahigh fields and relativistic protons. The bubble wall protons undergo volumetric acceleration toward the centre due to the spherically symmetric Coulomb force and the innermost protons accumulate at the centre with a density comparable to the interior of a white dwarf. Then an unprecedentedly high electric field is formed, which produces an energetic proton flash. Three-dimensional particle simulations confirm the robustness of Coulomb-imploded bubbles, which behave as nano-pulsars with repeated implosions and explosions to emit protons. Current technologies should be sufficient to experimentally verify concept of bubble implosions.

physics.plasm-ph↗
arXiv2023

Compact in-vacuum gamma-ray spectrometer for high-repetition rate PW-class laser-matter interaction

With the advent of high repetition rate laser facilities, novel diagnostic tools compatible with these advanced specifications are required. This paper presents the design of an active gamma-ray spectrometer intended for these high repetition rate experiments, with particular emphasis on functionality within a PW level laser-plasma interaction chamber's extreme conditions. The spectrometer uses stacked scintillators to accommodate a broad range of gamma-ray energies, demonstrating its adaptability for various experimental setups. Additionally, it has been engineered to maintain compactness, electromagnetic pulse resistance, and ISO-5 cleanliness requirements while ensuring high sensitivity. The spectrometer has been tested in real conditions inside the PW-class level interaction chamber at the BELLA center, LBNL. The paper also outlines the calibration process thanks to a $^{60}$Co radioactive source.

physics.plasm-ph↗
arXiv2023

Positron generation and acceleration in a self-organized photon collider enabled by an ultra-intense laser pulse

We discovered a simple regime where a near-critical plasma irradiated by a laser of experimentally available intensity can self-organize to produce positrons and accelerate them to ultra-relativistic energies. The laser pulse piles up electrons at its leading edge, producing a strong longitudinal plasma electric field. The field creates a moving gamma-ray collider that generates positrons via the linear Breit-Wheeler process -- annihilation of two gamma-rays into an electron-positron pair. At the same time, the plasma field, rather than the laser, serves as an accelerator for the positrons. The discovery of positron acceleration was enabled by a first-of-its-kind kinetic simulation that generates pairs via photon-photon collisions. Using available laser intensities of $10^{22}$$\ $$\rm W/cm^2$, the discovered regime can generate a GeV positron beam with divergence angle of $\sim10^{\circ}$ and total charge of 0.1$\ $pC. The result paves the way to experimental observation of the linear Breit-Wheeler process and to applications requiring positron beams.

physics.plasm-ph↗
arXiv2023

Direct laser acceleration in underdense plasmas with multi-PW lasers: a path to high-charge, GeV-class electron bunches

The direct laser acceleration (DLA) of electrons in underdense plasmas can provide 100s of nC of electrons accelerated to near-GeV energies using currently available lasers. Here we demonstrate the key role of electron transverse displacement in the acceleration and use it to analytically predict the expected maximum electron energies. The energy scaling is shown to be in agreement with full-scale quasi-3D particle-in-cell (PIC) simulations of a laser pulse propagating through a preformed guiding channel and can be directly used for optimizing DLA in near-future laser facilities. The strategy towards optimizing DLA through matched laser focusing is presented for a wide range of plasma densities paired with current and near-future laser technology. Electron energies in excess of 10 GeV are accessible for lasers at $I\sim 10^{21}~\mathrm{W/cm^2}$.

physics.plasm-ph↗
arXiv2021

Relativistically transparent magnetic filaments: scaling laws, initial results and prospects for strong-field QED studies

Relativistic transparency enables volumetric laser interaction with overdense plasmas and direct laser acceleration of electrons to relativistic velocities. The dense electron current generates a magnetic filament with field strength of the order of the laser amplitude ($>$10$^5$ T). The magnetic filament traps the electrons radially, enabling efficient acceleration and conversion of laser energy into MeV photons by electron oscillations in the filament. The use of microstructured targets stabilizes the hosing instabilities associated with relativistically transparent interactions, resulting in robust and repeatable production of this phenomenon. Analytical scaling laws are derived to describe the radiated photon spectrum and energy from the magnetic filament phenomenon in terms of the laser intensity, focal radius, pulse duration, and the plasma density. These scaling laws are compared to 3-D particle-in-cell (PIC) simulations, demonstrating agreement over two regimes of focal radius. Preliminary experiments to study this phenomenon at moderate intensity ($a_0 \sim 30$) were performed on the Texas Petawatt Laser. Experimental signatures of the magnetic filament phenomenon are observed in the electron and photon spectra recorded in a subset of these experiments that is consistent with the experimental design, analytical scaling and 3-D PIC simulations. Implications for future experimental campaigns are discussed.

physics.plasm-ph↗
arXiv2020

Birefringence in thermally anisotropic relativistic plasmas and its impact on laser-plasma interactions

One of the paradigm-shifting phenomena triggered in laser-plasma interactions at relativistic intensities is the so-called relativistic transparency. As the electrons become heated by the laser to relativistic energies, the plasma becomes transparent to the laser light even though the plasma density is sufficiently high to reflect the laser pulse in the non-relativistic case. This paper highlights the impact that relativistic transparency can have on laser-matter interactions by focusing on a collective phenomenon that is associated with the onset of relativistic transparency: plasma birefringence in thermally anisotropic relativistic plasmas. The optical properties of such a system become dependent on the polarization of light, and this can serve as the basis for plasma-based optical devices or novel diagnostic capabilities.

physics.plasm-ph↗
arXiv2019

Energy gain by laser-accelerated electrons in a strong magnetic field

The manuscript deals with electron acceleration by a laser pulse in a plasma with a static uniform magnetic field $B_*$. The laser pulse propagates perpendicular to the magnetic field lines with the polarization chosen such that $({\bf{E}}_{laser} \cdot {\bf{B}}_*) = 0$. The focus of the work is on the electrons with an appreciable initial transverse momentum that are unable to gain significant energy from the laser in the absence of the magnetic field due to strong dephasing. It is shown that the magnetic field can initiate an energy increase by rotating such an electron, so that its momentum becomes directed forward. The energy gain continues well beyond this turning point where the dephasing drops to a very small value. In contrast to the case of purely vacuum acceleration, the electron experiences a rapid energy increases with the analytically derived maximum energy gain dependent on the strength of the magnetic field and the phase velocity of the wave. The energy enhancement by the magnetic field can be useful at high laser amplitudes, $a_0 \gg 1$, where the acceleration similar to that in the vacuum is unable to produce energetic electrons over just tens of microns. A strong magnetic field helps leverage an increase in $a_0$ without a significant increase in the interaction length.

physics.plasm-ph↗
arXiv2019

Collimated gamma-ray beams from structured laser-irradiated targets -- how to increase the efficiency without increasing the laser intensity

Using three-dimensional kinetic simulations, we examine the emission of collimated gamma-ray beams from structured laser-irradiated targets with a pre-filled cylindrical channel. The channel guides the incident laser pulse, enabling generation of a slowly evolving azimuthal plasma magnetic field that serves two key functions: to enhance laser-driven electron acceleration and to induce emission of gamma-rays by the energetic electrons. Our main finding is that the conversion efficiency of the laser energy into a beam of gamma-rays ($5^{\circ}$ opening angle) can be significantly increased without increasing the laser intensity by utilizing channels with an optimal density. The conversion efficiency into multi-MeV photons increases roughly linearly with the incident laser power $P$, as we increase $P$ from 1 PW to 4 PW while keeping the laser peak intensity fixed at $5 \times 10^{22}$ W/cm$^2$. This scaling is achieved by using an optimal range of plasma densities in the channel between 10 and $20 n_{cr}$, where $n_{cr}$ is the classical cutoff density for electromagnetic waves. The corresponding number of photons scales as $P^2$. One application that directly benefits from such a strong scaling is the pair production via two-photon collisions, with the number of generated pairs increasing as $P^4$ at fixed laser intensity.

physics.plasm-ph↗
arXiv2010

Belle II Technical Design Report

The Belle detector at the KEKB electron-positron collider has collected almost 1 billion Y(4S) events in its decade of operation. Super-KEKB, an upgrade of KEKB is under construction, to increase the luminosity by two orders of magnitude during a three-year shutdown, with an ultimate goal of 8E35 /cm^2 /s luminosity. To exploit the increased luminosity, an upgrade of the Belle detector has been proposed. A new international collaboration Belle-II, is being formed. The Technical Design Report presents physics motivation, basic methods of the accelerator upgrade, as well as key improvements of the detector.

physics.ins-det↗
arXiv2009

Technical Design Report for the PANDA Solenoid and Dipole Spectrometer Magnets

This document is the Technical Design Report covering the two large spectrometer magnets of the PANDA detector set-up. It shows the conceptual design of the magnets and their anticipated performance. It precedes the tender and procurement of the magnets and, hence, is subject to possible modifications arising during this process.

physics.ins-det↗
arXiv2009

Physics Performance Report for PANDA: Strong Interaction Studies with Antiprotons

To study fundamental questions of hadron and nuclear physics in interactions of antiprotons with nucleons and nuclei, the universal PANDA detector will be built. Gluonic excitations, the physics of strange and charm quarks and nucleon structure studies will be performed with unprecedented accuracy thereby allowing high-precision tests of the strong interaction. The proposed PANDA detector is a state-of-the art internal target detector at the HESR at FAIR allowing the detection and identification of neutral and charged particles generated within the relevant angular and energy range. This report presents a summary of the physics accessible at PANDA and what performance can be expected.

hep-ex↗
arXiv2008

Technical Design Report for PANDA Electromagnetic Calorimeter (EMC)

This document presents the technical layout and the envisaged performance of the Electromagnetic Calorimeter (EMC) for the PANDA target spectrometer. The EMC has been designed to meet the physics goals of the PANDA experiment, which is being developed for the Facility for Antiproton and Ion Research (FAIR) at Darmstadt, Germany. The performance figures are based on extensive prototype tests and radiation hardness studies. The document shows that the EMC is ready for construction up to the front-end electronics interface.

physics.ins-det↗
arXiv1998

Design and Operation of Front-End Electronics for the HERA-B Muon Detector

We have implemented a cost-effective design for the readout electronics of both the anode wires and the cathode pads of large area proportional wire chambers for the HERA-B muon system based on the ASD-08 integrated circuit. To control and monitor the large number of readout channels, we have built a distributed control system based on Philips Semiconductors' I2C bus and microcontrollers. To date we have installed about 10800 channels of muon chambers and electronics. The average single channel noise occupancy is less than 10**-5, and the detectors have been operated with target interaction rates as high as 70 MHz.

physics.ins-det↗