Thermal simulations for optical transition radiation screen for Eli-NP compton gamma source

The ELI-NP GBS (Extreme Light Infrastructure-Nuclear Physics Gamma Beam Source) is a high brightness elec-tron LINAC that is being built in Romania. The goal for this facility is to provide high luminosity gamma beam through Compton Backscattering. A train of 32 bunches at 100Hz with a nominal charge of 250pC is accelerated up to 740 MeV. Two interaction points with an IR Laser beam produces the gamma beam at different energies. In order to measure the electron beam spot size and the beam proper-ties along the train, the OTR screens must sustain the ther-mal and mechanical stress due to the energy deposited by the bunches. This paper is an ANSYS study of the issues due to the high quantity of energy transferred to the OTR screen. They will be shown different analysis, steady-state and thermal transient analysis, where the input loads will be the internal heat generation equivalent to the average power, deposited by the ELI-GBS beam in 512 ns, that is the train duration. Each analyses will be followed by the structural analysis to investigate the performance of the OTR materi

Thermal issues for the optical transition radiation screen for the ELI-NP compton gamma source

A high brightness electron LINAC is being built in the Compton Gamma Source at the ELI Nuclear Physics facility in Romania. To achieve the design luminosity, a train of 32 bunches, 16 ns spaced, with a nominal charge of 250 pC will collide with a laser beam in two interaction points. Electron beam spot size is measured with Optical Transition Radiation (OTR) profile monitors. In order to measure the beam properties, the OTR screens must sustain the thermal and mechanical stress due to the energy deposited by bunches. This paper is an ANSYS study of the issues due to the high energy transferred to the OTR screens. Thermal multicycle analysis will be shown; each analysis will be followed by a structural analysis in order to investigate the performance of the materia

Conceptual design of electron beam diagnostics for high brightness plasma accelerator

A design study of the diagnostics of a high brightness linac, based on X-band structures, and a plasma accelerator stage, has been delivered in the framework of the EuPRAXIA@SPARC_LAB project. In this paper, we present a conceptual design of the proposed diagnostics, using state of the art systems and new and under development devices. Single shot measurements are preferable for plasma accelerated beams, including emittance, while $\mu$m level and fs scale beam size and bunch length respectively are requested. The needed to separate the driver pulse (both laser or beam) from the witness accelerated bunch imposes additional constrains for the diagnostics. We plan to use betatron radiation for the emittance measurement just at the end of the plasma booster, while other single-shot methods must be proven before to be implemented. Longitudinal measurements, being in any case not trivial for the fs level bunch length, seem to have already a wider range of possibilities

What should a quantitative model of masking look like and why would we want it?

Quantitative models of backward masking appeared almost as soon as computing technology was available to simulate them; and continued interest in masking has lead to the development of new models. Despite this long history, the impact of the models on the field has been limited because they have fundamental shortcomings. This paper discusses these shortcomings and outlines what future quantitative models should look like. It also discusses several issues about modeling and how a model could be used by researchers to better explore masking and other aspects of cognition

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 2π/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 MV/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

Nanocarriers for neuromuscular diseases

Overview of the results obtained so far in the frame of a research on suitable nanocarriers for treating myotonic dystroph

High power test results of the Eli-NP S-Band gun fabricated with the new clamping technology without brazing

High gradient RF photoguns have been a key development to enable several applications of high quality electron beams. They allow the generation of beams with very high peak current and low transverse emittance, thus satisfying the tight demands of free-electron lasers, energy recovery linacs, Compton/Thomson sources and high-energy linear colliders. A new fabrication technique for this type of structures has been recently developed and implemented at the Laboratories of Frascati of the National Institute of Nuclear Physics (INFN-LNF, Italy). It is based on the use of special RF-vacuum gaskets, that allow a brazing-free realization process. The S-band gun of the ELI-NP gamma beam system (GBS) has been fabricated with this new technique. It operates at 100 Hz with 120 MV/m cathode peak field and 1.5 μs long RF pulses to house the 32 bunches necessary to reach the target gamma flux. High gradient tests, performed at full power and full repetition rate, have shown extremely good performances of the structure in terms of breakdown rate. In the paper, we report and discuss all the experimental results, the electromagnetic design and the mechanical realization processes

Longitudinal phase-space manipulation with beam-driven plasma wakefields

The development of compact accelerator facilities providing high-brightness beams is one of the most challenging tasks in field of next-generation compact and cost affordable particle accelerators, to be used in many fields for industrial, medical and research applications. The ability to shape the beam longitudinal phase-space, in particular, plays a key role to achieve high-peak brightness. Here we present a new approach that allows to tune the longitudinal phase-space of a high-brightness beam by means of a plasma wakefields. The electron beam passing through the plasma drives large wakefields that are used to manipulate the time-energy correlation of particles along the beam itself. We experimentally demonstrate that such solution is highly tunable by simply adjusting the density of the plasma and can be used to imprint or remove any correlation onto the beam. This is a fundamental requirement when dealing with largely time-energy correlated beams coming from future plasma accelerators

Multiple detection and spread of novel strains of the SARS-CoV-2 B.1.177 (B.1.177.75) lineage that test negative by a commercially available nucleocapsid gene real-time RT-PCR

Several lineages of SARS-CoV-2 are currently circulating worldwide. During SARS-CoV-2 diagnostic activities performed in Abruzzo region (central Italy) several strains belonging to the B.1.177.75 lineage tested negative for the N gene but positive for the ORF1ab and S genes (+/+/- pattern) by the TaqPath COVID-19 CE-IVD RT-PCR Kit manufactured by Thermofisher. By sequencing, a unique mutation, synonymous 28948C > T, was found in the N-negative B.1.177.75 strains. Although we do not have any knowledge upon the nucleotide sequences of the primers and probe adopted by this kit, it is likely that N gene dropout only occurs when 28948C > T is coupled with 28932C > T, this latter present, in turn, in all B.1.177.75 sequences available on public databases. Furthermore, epidemiological analysis was also performed. The majority of the N-negative B.1.177.75 cases belonged to two clusters apparently unrelated to each other and both clusters involved young people. However, the phylogeny for sequences containing the +/+/- pattern strongly supports a genetic connection and one common source for both clusters. Though, genetic comparison suggests a connection rather than indicating the independent emergence of the same mutation in two apparently unrelated clusters. This study highlights once more the importance of sharing genomic data to link apparently unrelated epidemiological clusters and to, remarkably, update molecular tests