Extreme Light Infrastructure - Nuclear Physics Research Articles

GPE - a Compact Gamma-Ray Polarimeter with Energy Reconstruction Capability

We present here the design, expected parameters and performance tests of a compact detector, based on INTPIX4 sensing device, developed in the framework of the Extreme Light Infrastructure – Nuclear Physics (ELI-NP) project, capable of measuring both polarization and energy of gamma rays, in the high energy range above 1 GeV. The detector, based on electron-positron pair creation in the BetheHeitler process, has been tested with cosmogenic muons and will allow unique experiments at the ELI-NP facility.

A tool for beam optics design and its application on the VEGA transport line at ELI-NP

The Variable Energy Gamma (VEGA) System, currently under construction at Extreme Light Infrastructure-Nuclear Physics (ELI-NP), is a storage ring-based gamma beam source that aims to provide gamma-ray beams with a variable energy range from 1 MeV to 19.5 MeV to the users. The electron beam transport line has been designed to connect the linear accelerator and the storage ring in the VEGA electron beam system. Considering the geometrical constraints in the accelerator halls and the location of the injection point at the storage ring, the trajectory of the electron beam in the transport line has to first ascend by a 36-degree dog-leg elevation to align with a plane parallel to the storage ring, undergo a 180-degree horizontal turn, and then descend by 36 degrees vertically to reach the injection point at the storage ring. In this paper, we introduce a beam optics tool implemented for the beam optics design and fine-matching in the electron beam transport line. The design of the VEGA transport line including the layout and lattice design, is also described. The tool has been applied to the beam optics design and optimization, utilizing tracking simulations and beam matching for the VEGA transport line lattice. Furthermore, the tool's potential application to similar lattice designs is also discussed.

Classification of laser beam profiles using machine learning at the ELI-NP high power laser system

The high power laser system at Extreme Light Infrastructure—Nuclear Physics has demonstrated 10 PW power shot capability. It can also deliver beams with powers of 1 PW and 100 TW in several different experimental areas that carry out dedicated sets of experiments. An array of diagnostics is deployed to characterize the laser beam spatial profiles and to monitor their evolution during the amplification stages. Some of the essential near-field and far-field profiles acquired with CCD cameras are monitored constantly on a large screen television for visual observation and for decision making concerning the control and tuning of the laser beams. Here, we present results on the beam profile classification obtained from datasets with over 14 600 near-field and far-field images acquired during two days of laser operation at 1 PW and 100 TW. We utilize supervised and unsupervised machine learning models based on trained neural networks and an autoencoder. These results constitute an early demonstration of machine learning being used as a tool in the laser system data classification.

The annealing setup and associated monitoring system of the ELIADE HPGe clover detectors at ELI-NP

We report a dedicated setup built in-house for the annealing of the HPGe clover detectors of the ELI-NP Array of DEtectors (ELIADE) γ-ray spectrometer, as well as the post-annealing testing of these detectors with the standard 60Co & 152Eu radioactive calibration sources employing conventional analog electronics. Both the design and assembly of the annealing setup were performed at the Extreme Light Infrastructure — Nuclear Physics (ELI-NP) facility, Măgurele, Romania. A `radiation damage annealing assembly kit' (NRK-200 unit) from the detector manufacturer Canberra is utilized in heating and controlling the temperature of the Ge crystals of the annealed detector. The vacuum inside the detector was maintained throughout the annealing process by constantly pumping the system using a turbo-molecular pumping station. The temperature of the germanium crystals, located inside a vacuum sealed chamber, of the detector and the vacuum level of this chamber were monitored throughout the annealing process, via both in-person observation and remote (online) monitoring. The Graphic User Interface (GUI) of an underlying LabVIEW script was utilized for running the monitoring process of the temperature and vacuum pressure values via a local network. To have the option of real-time online monitoring of the temperature, vacuum pressure, we coupled the web application Grafana with the Influx DB of the annealing data, as well as the backup time information of an Uninterruptible Power Supply (UPS) unit used in system.

A setup for high-energy [formula omitted]-ray spectroscopy with the ELI-NP large-volume LaBr3:Ce and CeBr3 detectors at the 9 MV Tandem accelerator at IFIN-HH

We have performed the first experimental campaign using large-volume LaBr3:Ce and CeBr3 detectors from several of the Extreme Light Infrastructure-Nuclear physics (ELI-NP) instrumental setups together with detectors and infrastructure from the ROSPHERE array at the 9 MV Tandem facility at the Horia Hulubei National Institute for Physics and Nuclear Engineering (IFIN-HH). The performance of the detectors and the digital data acquisition system is shown to give a good energy resolution at high energies, and an excellent time resolution. We, furthermore, present the possibilities to integrate the detector system and the digital electronics with various ancillary detectors for, for example, charged particles.

Nuclear photonics: Laser-driven nuclear physics

High-power lasers can produce high-energy gamma rays, charged particles, and neutrons and induce various types of nuclear reactions. In Extreme Light Infrastructure Nuclear Physics (ELI-NP), Romania, high-power lasers are entering a new realm of 10 PW peak power, capable of obtaining a focused intensity of 1023 Wcm–2. Such an intense laser pulse will be used for studies relevant to nuclear physics, high-field physics, and quantum electrodynamics, or the combination of laser gamma experiments. Here, we describe how a laser is used to drive high-energy photons and accelerate electrons and protons. These particles can be used for secondary interactions in nuclear physics. Laser-driven nuclear physics can be a source of nuclear isomers for applications in medicine and astrophysics.

Laser-driven muon production for material inspection and imaging

We numerically show that laser-wakefield accelerated electron beams obtained using a PetaWatt-scale laser system can produce high-flux sources of relativistic muons that are suitable for radiographic applications. Scalings of muon energy and flux with the properties of the wakefield electron beams are presented. Applying these results to the expected performance of the 10-PW class laser at the Extreme Light Infrastructure Nuclear Physics (ELI-NP) demonstrates that ultra-high power laser facilities currently in the commissioning phase can generate ultra-relativistic muon beams with more than 104 muons per shot reaching the detector plane. Simple magnetic beamlines are shown to be effective in separating the muons from noise, allowing for their detection using, for example, silicon-based detectors. It is shown that a laser facility like the one at ELI-NP can produce high-fidelity and spatially resolved muon radiographs of enclosed strategically sensitive materials in a matter of minutes.

What can we learn from experiments with high-brilliance gamma beams?

An overview of the main directions of present-day studies with quasimonochromatic γ beams is presented with an emphasis on the research opportunities which will be provided to the users at the Extreme Light Infrastructure Nuclear Physics (ELI-NP) facility at Magurele near Bucharest. Experiments with γ beams at the extremes of high temperature and high neutron-to-proton ratios will be discussed. The opportunities for nuclear structure studies with γ rays with orbital angular momentum (OAM) are outlined and a few selected physics problems and classes of experiments, related to, e.g., changes of photonuclear cross sections in reactions with OAM photons, as well as the possibility to address nuclear excitations with higher multipolarity are discussed. The perspectives for studies of exotic nuclei within the Gamma Factory experiment at CERN are discussed, too.

Nuclear astrophysics studies with γ-ray beams: What do we expect to learn from them?

An overview of the main directions of present-day studies with quasimonochromatic γ beams is discussed with an emphasis on the research opportunities which will be offered at the Extreme Light Infrastructure Nuclear Physics (ELI-NP) facility at Magurele near Bucharest in Romania. Experiments with γ beams at the extremes of high temperatures are outlined, with an emphasis on prospective studies related to nuclear astrophysics and astroparticle physics. Some of the experimental setups for nuclear structure, reaction, and astrophysics studies, which are available at ELI-NP, are described.

Liquid nitrogen cooling, control and monitoring system for the ELIADE HPGe clover detectors at ELI-NP

We present a liquid nitrogen (LN2) cooling station for the high-purity germanium (HPGe) segmented clover detectors of the ELI-NP Array of DEtectors (ELIADE) spectrometer, including its associated filling control and monitoring systems, all designed and built in-house at Extreme Light Infrastructure - Nuclear Physics (ELI-NP), Măgurele, Romania. The automated LN2 filling process is controlled by a CompactRIO (cRIO) system from National Instruments through a custom LabVIEW software used for monitoring both the internal germanium crystal temperatures as well as the temperatures of external Pt100 sensors (used for detection of overflow of LN2 from detectors during a filling process). The detectors are filled with LN2 by opening their individual filling valves (which are mounted on the cooling station) and the process is automatically stopped once an overflow condition is fulfilled by the corresponding external Pt100 sensor located downstream. A twelve-hour cycle is used to periodically fill all of the detector dewars and keep their germanium crystals cool at all times. The associated Graphic User Interface (GUI), Command Line Interface (CLI) and Text User Interface (TUI) are used for both controlling and monitoring the above mentioned process. Alert and warning email messages were also enabled via the cRIO system so that users can be alerted in real-time in the event of any cooling malfunction. In this way, any issues related to the cyclic filling procedure, as well as any abnormal observations regarding the germanium crystal temperatures can be quickly and efficiently addressed before the detectors have a chance to warm back up to room temperature. Temperature data of all the Pt100 sensors corresponding to detectors as well as to the solenoid valves are made available in an influx database by the cRIO control system. The web application Grafana access the database and plots them in real-time for online monitoring.

10 PW Peak Power Laser at the Extreme Light Infrastructure Nuclear Physics – status updates

We have shown, for the first time in the world, the production of 10 PW peak power laser pulses and their propagation to an experimental area at the Extreme Light Infrastructure - Nuclear Physics (ELI-NP). We are also steadily running the laser system for experimental campaigns, increasing the output power levels delivered for experiments and fine-tuning the parameters of the laser pulses, the operational procedures, and the operational teams. During our presentation, we will show the laser developments at ELI-NP emphasizing the 10 PW peak power demonstrations and the latest results for the HPLS beam delivery.

First in-beam experiment with the ELIADE detectors: a spectroscopic study of 130La

The new facility, Extreme Light Infrastructure – Nuclear Physics (ELI-NP), is a combined laser-gamma nuclear physics research facility currently undergoing its final implementation stages in Măgurele near Bucharest, Romania. It already hosts two fully-operational 10 PW laser arms and, by 2023, it will also house a γ-beam system based on laser Compton backscattering, capable of delivering a high-brilliance, low-energy beam at E γ ≲ 19.5 MeV. Owing to this unique laser-gamma instrumentation combination, several types of experiments will be possible at ELI-NP, including high precision nuclear resonance fluorescence (NRF) experiments. In this case, the main γ-beam detection system for performing NRF studies at ELI-NP is represented by the ELI Array of DEtectors (ELIADE), featuring eight high-purity germanium (HPGe) segmented clover detectors. The current work presents the characteristics of two of the ELIADE detectors, including their photopeak detection efficiency, energy resolution, and peak-to-total ratio measured using γ-ray sources, as well as the timing performance obtained via in-beam measurements. For these latter detector tests, 130La was populated via the fusion evaporation reaction 121Sb(12C,3n)130La using a beam energy of 53 MeV at the Horia Hulubei National Institute of Physics and Nuclear Engineering (IFIN-HH), also located in Măgurele. Herein, we report on the results of the ^130La linear polarization measurements taken using the ELIADE detectors as Compton polarimeters. The results obtained from the in-beam experiment were compared to several already published works and we present new information on the transition multipolarity in 130La.

Experimental programme with high-brilliance gamma beams at ELI-NP

The emerging experimental program with brilliant gamma beams at the Extreme Light Infrastructure – Nuclear Physics (ELI-NP) facility is presented with emphasis on the day-one experiments which are under preparation. Experiments at ELI-NP will cover nuclear resonance fluorescence (NRF) measurements, studies of large-amplitude motions in nuclei, photo-fission and photonuclear reactions of astrophysics interest, and measurements of photonuclear reaction cross-sections. The physics cases of the flagship experiments at ELI-NP and the performance of the related instruments, which are under construction for their realization, are discussed.

Near-100 mev proton acceleration from 1021 W/cm2 laser interacting with near-critical density plasma

Ion acceleration with linearly polarized 1 petawatt (PW) intense laser pulses interacting with near critical density (NCD) gas targets was demonstrated by using two-dimensional (2D) particle-in-cell (PIC) simulations. The laser parameters considered are comfortably within the capabilities of PW laser facilities, e.g., Extreme Light Infrastructure - Nuclear Physics (ELI-NP), Shanghai Superintense Ultrafast Laser Facility (SULF) and China Academy of Engineering Physics (CAEP). PIC simulation results show that near-100 MeV proton acceleration could be stably achieved within the optimized plasma parameters range, which is a result of the Magnetic Vortex Acceleration (MVA) mechanisms and the longitudinal charge-separation field formed along the filament. Our results indicate that proton energies reaching 100 MeV, benefiting for numerous advanced applications, e.g., the treatment of proton therapy at eyes, are already accessible within the capability of currently laser facilities.

Overview of ELI-NP status and laser commissioning experiments with 1 PW and 10 PW class-lasers

In the last decade, the laser intensity has reached up to 1021 Wcm−2 on focus allowing the generation of new phenomena, which are relevant not only in basic physics research but also in applied science with great benefit to the society. In this regard, in 2006, the Extreme Light Infrastructure project was considered in the roadmap of ESFRI with the aim of creating European research centers for cutting-edge studies. From the three pillars under development, the Romanian one, denominated ELI-NP (Extreme Light Infrastructure Nuclear Physics), will be broadly studying the laser-plasma interaction by employing a 10 PW class-laser with the intent of studying the behavior of matter exposed at extreme light intensities and consequently producing specific ion and gamma-ray sources of relevance for nuclear physics. For instance, phenomena like the Target Normal Sheath Acceleration (TNSA) and the Radiation Pressure Acceleration (RPA) will be widely investigated in a new regime in which Quantum electrodynamics (QED) effects start to play a significant role. Particle-In-Cell (PIC) simulations and theoretical models predict ion beams with energies up to sub-GeV/u and gamma-ray pulses of the order of few petawatts from a 10 PW laser beam (i.e. laser intensity of about 1023 Wcm−2). Further, multi-GeV electron beams of quality suitable for applications are expected to be attained from gas targets via LWFA (Laser Wakefield Acceleration). The active investigation which will be pursued in the coming years at ELI-NP will certainly bring to the discovery of novel physics phenomena and several applications. The commissioning of the experimental areas dedicated to research with high power lasers and a gradual entering in operation will take place during 2020–2021.

Realization and high power test of damped C -band accelerating structures

The linac of the European project Extreme Light Infrastructure-Nuclear Physics (ELI-NP) foresees the use of 12 traveling wave $C$-band accelerating structures. The cavities are 1.8 m long, quasiconstant gradient, and have a field phase advance per cell of $2\ensuremath{\pi}/3$. They operate at 100 Hz repetition rate, and, because of the multibunch operation, they have been designed with a dipole higher-order mode (HOM) damping system to avoid beam breakup. The structures have symmetric input and output couplers and integrate, in each cell, a damping system based on silicon carbide (SiC) rf absorbers coupled to each cell through waveguides. An optimization of the electromagnetic and mechanical design has been done to simplify the fabrication and to reduce the costs. The cavities have been fabricated, and the first full-scale prototype has been also successfully tested at the nominal gradient of $33\text{ }\text{ }\mathrm{MV}\mathrm{/m}$, repetition rate of 100 Hz, and pulse length of 820 ns. It represents, to our knowledge, the first full-scale linac structure with HOM damping waveguides and SiC absorbers tested at this high gradient. In the paper, we illustrate the realization process of such a complicated device together with the low and high power test results.

Paradigm Shift to the European Business Model. Extreme Light Infrastructure – Nuclear Physics Project. Study Case

The multipliers of paradigm shift in economy are abundance, change of micro and macroeconomic equilibrium, and increased intensity in creativity at the level of economic processes. Authors starts from the hypothesis that in the field of economics and business, a number of enthusiastic approaches to paradigm shift must be taken with some reservations as functional market have their specificity, the public choice logic is very well represented, the idea of social learning is present more than in other fields and the principle of economic rationality has great applicability. The most important characteristics of the new European industry are: is based on three pillars: strong educational system, scientific research and high-tech; advanced research is an integrative industry; the results of the advanced research are an Open Source. The analysis is based on the quadruple helix logic, authors analyzing the Extreme Light Infrastructure - Nuclear Physics (ELI-NP). As development of a country could be based on few advanced research projects and it is possible to use this experience for the whole region, new engines of the European economy, will be: nuclear research, extreme intensity light research and astronautics, the new industry will develop a large range of activities and jobs which will modify the labor map and the relocation of large companies to Europe will be one of the concrete result of the stimulating the advanced research.
 
 Keywords: Paradigm shift, business model, infrastructure, technological challenges

High-energy hybrid femtosecond laser system demonstrating 2 × 10 PW capability

Abstract We report on a two-arm hybrid high-power laser system (HPLS) able to deliver 2 × 10 PW femtosecond pulses, developed at the Bucharest-Magurele Extreme Light Infrastructure Nuclear Physics (ELI-NP) Facility. A hybrid front-end (FE) based on a Ti:sapphire chirped pulse amplifier and a picosecond optical parametric chirped pulse amplifier based on beta barium borate (BBO) crystals, with a cross-polarized wave (XPW) filter in between, has been developed. It delivers 10 mJ laser pulses, at 10 Hz repetition rate, with more than 70 nm spectral bandwidth and high-intensity contrast, in the range of 1013:1. The high-energy Ti:sapphire amplifier stages of both arms were seeded from this common FE. The final high-energy amplifier, equipped with a 200 mm diameter Ti:sapphire crystal, has been pumped by six 100 J nanosecond frequency doubled Nd:glass lasers, at 1 pulse/min repetition rate. More than 300 J output pulse energy has been obtained by pumping with only 80% of the whole 600 J available pump energy. The compressor has a transmission efficiency of 74% and an output pulse duration of 22.7 fs was measured, thus demonstrating that the dual-arm HPLS has the capacity to generate 10 PW peak power femtosecond pulses. The reported results represent the cornerstone of the ELI-NP 2 × 10 PW femtosecond laser facility, devoted to fundamental and applied nuclear physics research.

The ELI-NP IGISOL radioactive ion beam facility

The Extreme Light Infrastructure – Nuclear Physics (ELI-NP) laboratory in Bucharest, Romania, will host an IGISOL-type facility which will study exotic neutron-rich ion beams produced via photo-fission in actinide targets placed at the center of a cryogenic gas cell. Using a complex radio frequency quadrupole for radioactive ion beam formation, a powerful multiple-reflection time-of-flight mass spectrometer for selecting the refractory isotopes of interest, and several measurement stations, this facility will be an exciting new tool for nuclear scientists. The two mechanisms of ion transport inside the gas cell, namely drift by electric fields and drag by supersonic gas jets, are studied. A program to test the individual components of the stopping cell is discussed.

Wind Tunnel Experiment for Pedestrian Wind Comfort in Sun Valley Campus

Various urban spaces around the world, were designed and built in respect with the design theories in order to satisfy different requests of users and inhabitants and to provide a quality urban spaces. The use of these spaces by the city citizen depends on many factors that influence their decision while choosing the urban space where to spend time. Among these factors, the comfort provided in any area is a crucial determinant that depend mainly on a wide range of climatic parameters such as air temperature, wind velocity, relative humidity, solar radiation etc. However, the impact of the micro-climates parameters on the user’s comfort in these open spaces has often been ignored and architects tend to pay more attention and consider the indoor comfort, but they may not consider the effect of their buildings on the outdoor environment, and pedestrian comfort. The article concerns an experimental study on the effects of the wind velocity on the pedestrian comfort and safety in a campus inside a bigger project called Laser Valley Land of Lights. With the purpose to provide a project with a complete harmony with the physical elements of the environment. Due to the fact that the interaction between the wind and the city buildings, create aerodynamic phenomena around building that impact directly the outdoor environment and make the study of the human outdoor comfort more complex. The study was carried out at the Aerodynamics and Wind Engineering Laboratory “Constantin Iamandi” (LAIV) from the Technical University of Civil Engineering Bucharest (UTCB). The project Laser Valley Land of Lights aims to implement the world’s most powerful laser, Extreme Light Infrastructure Nuclear Physics ELI NP Project. The campus under study won an international competition by providing an open research ecosystem taking into consideration that is based on green building and sustainable development. In this paper we describe the result obtained from the experiment performed in the TASL1-M Boundary Layer Wind Tunnel on the effects of the wind on the pedestrian comfort and the mitigation solution proposed for the critical and uncomfortable areas detected.