131 research outputs found
EuPRAXIA@SPARC_LAB: the high-brightness RF photo-injector layout proposal
At EuPRAXIA@SPARC_LAB, the unique combination of an advanced high-brightness
RF injector and a plasma-based accelerator will drive a new multi-disciplinary
user-facility. The facility, that is currently under study at INFN-LNF
Laboratories (Frascati, Italy) in synergy with the EuPRAXIA collaboration, will
operate the plasma-based accelerator in the external injection configuration.
Since in this configuration the stability and reproducibility of the
acceleration process in the plasma stage is strongly influenced by the
RF-generated electron beam, the main challenge for the RF injector design is
related to generating and handling high quality electron beams. In the last
decades of R&D activity, the crucial role of high-brightness RF photo-injectors
in the fields of radiation generation and advanced acceleration schemes has
been largely established, making them effective candidates to drive
plasma-based accelerators as pilots for user facilities. An RF injector
consisting in a high-brightness S-band photo-injector followed by an advanced
X-band linac has been proposed for the EuPRAXIA@SPARC_LAB project. The electron
beam dynamics in the photo-injector has been explored by means of simulations,
resulting in high-brightness, ultra-short bunches with up to 3 kA peak current
at the entrance of the advanced X-band linac booster. The EuPRAXIA@SPARC_LAB
high-brightness photo-injector is described here together with performance
optimisation and sensitivity studies aiming to actual check the robustness and
reliability of the desired working point.Comment: 5 pages,5 figures, EAAC201
EUPRAXIA@SPARC_LAB: Beam Dynamics studies for the X-band Linac
In the framework of the Eupraxia Design Study an advanced accelerator
facility EUPRAXIA@SPARC_LAB has been proposed to be realized at Frascati
(Italy) Laboratories of INFN. Two advanced acceleration schemes will be
applied, namely an ultimate high gradient 1 GeV X-band linac together with a
plasma acceleration stage to provide accelerating gradients of the GeV/m order.
A FEL scheme is foreseen to produce X-ray beams within 3-10 nm range. A 500-TW
Laser system is also foreseen for electron and ion production experiments and a
Compton backscattering Interaction is planned together with extraction
beamlines at intermediate electron beam energy for neutron beams and THz
radiation production. The electron beam dynamics studies in the linac are here
presented together with the preliminary machine layout.Comment: 5 pages, 3 figures, NIM-A proceedings of EAAC201
Electromagnetic and beam dynamics studies for high gradient accelerators at terahertz frequencies
THz radiation is one of the most appealing portion of the electromagnetic spectrum in terms of multi-disciplinary use in basic science and technology. Beyond the numerous applications, a great interest is its potential for future, compact linear accelerators. Conventional radio-frequency accelerating structures operating at the S and C band can reach gradients up to 30 - 50MV/m, respectively; higher accelerating gradients, of the order of 100MV/m, have been obtained with X-band cavities. THz-based accelerating structures enable operation at even higher gradient, potentially up to the GV/m scale, holding great potential for their application to free-electron lasers and linear colliders, for instance. Here we present electromagnetic and beam dynamics studies about the use of a dielectric loaded waveguide to accelerate electron bunches by mean of a narrow-band multi-cycle THz pulse. The excitation of the accelerating structure by the THz pulse and the bunch acceleration in the excited field are investigated through CST Microwave Studio and GPT simulations
Exploratory data analysis on the effects of non pharmacological treatment for knee osteoarthritis
Nailfold capillaroscopy abnormalities are associated with the presence of anti-endothelial cell antibodies in Sjogren's syndrome
[No abstract available
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
Epstein-Barr virus persistence and infection of autoreactive plasma cells in synovial lymphoid structures in rheumatoid arthritis.
OBJECTIVES:
Rheumatoid arthritis (RA) is associated with an increased Epstein-Barr virus (EBV) blood DNA load, a robust immune response to EBV and cross-reactive circulating antibodies to viral and self-antigens. However, the role of EBV in RA pathogenesis remains elusive. Here, we investigated the relationship between synovial EBV infection, ectopic lymphoid structures (ELS) and immunity to citrullinated self and EBV proteins.
METHODS:
Latent and lytic EBV infection was investigated in 43 RA synovial tissues characterised for presence/absence of ELS and in 11 control osteoarthritis synovia using RT-PCR, in situ hybridisation and immunohistochemistry. Synovial production of anti-citrullinated protein (ACPA) and anti-citrullinated EBV peptide (VCP1/VCP2) antibodies was investigated in situ and in vivo in the severe combined immunodeficiency (SCID)/RA chimeric model.
RESULTS:
EBV dysregulation was observed exclusively in ELS+ RA but not osteoarthritis (OA) synovia, as revealed by presence of EBV latent (LMP2A, EBV-encoded small RNA (EBER)) transcripts, EBER+ cells and immunoreactivity for EBV latent (LMP1, LMP2A) and lytic (BFRF1) antigens in ELS-associated B cells and plasma cells, respectively. Importantly, a large proportion of ACPA-producing plasma cells surrounding synovial germinal centres were infected with EBV. Furthermore, ELS-containing RA synovia transplanted into SCID mice supported production of ACPA and anti-VCP1/VCP2 antibodies. Analysis of CD4+ and CD8+ T-cell localisation and granzyme B expression suggests that EBV persistence in ELS-containing synovia may be favoured by exclusion of CD8+ T cells from B-cell follicles and impaired CD8-mediated cytotoxicity.
CONCLUSIONS:
We demonstrated active EBV infection within ELS in the RA synovium in association with local differentiation of ACPA-reactive B cells
RF injector design studies for the trailing witness bunch for a plasma-based user facility
The interest in plasma-based accelerators as drivers of user facilities is
growing worldwide thanks to its compactness and reduced costs. In this context
the EuPRAXIA collaboration is preparing a conceptual design report for a
multi-GeV plasma-based accelerator with outstanding electron beam quality to
pilot, among several applications, the operation of an X-ray FEL, the most
demanding in terms of beam brightness. Intense beam dynamics studies have been
performed to provide a reliable working point for the RF injector to generate a
high-brightness trailing witness bunch suitable in external injection schemes,
both in particle beam and laser driven plasma wakefield acceleration. A case of
interest is the generation of a witness beam with 1 GeV energy, less than 1
mm-mrad slice emittance and 30 pC in 10 fs FWHM bunch length, which turns into
3 kA peak current at the undulator entrance. The witness beam has been
successfully compressed down to 10 fs in a conventional SPARC-like
photo-injector and boosted up to 500 MeV in an advanced high-gradient X-band
linac reaching the plasma entrance with 3 kA peak current and the following RMS
values: 0.06% energy spread, 0.5 mm-mrad transverse normalised emittance and a
focal spot down to 1 . RF injector studies are here presented with the
aim to satisfy the EuPRAXIA requests for the Design Study of a plasma-based
user facility.Comment: 5 pages, 7 figures, European Advanced Accelerator Concepts 201
Temperature analysis in the shock waves regime for gas-filled plasma capillaries in plasma-based accelerators
Plasma confinement represents a crucial point for plasma-based accelerators and plasma lenses because it can strongly affect the beam properties. For this reason, an accurate measurement of the plasma parameters, as plasma temperature, pressure and electron density, must be performed. In this paper, we introduce a novel method to detect the plasma temperature and the pressure for gas-filled capillaries in use at the SPARC-LAB test facility. The proposed method is based on the shock waves produced at the ends of the capillary during the gas discharge and the subsequent plasma formation inside it. By measuring the supersonic speed of the plasma outflow, the thermodynamic parameters have been obtained both outside and inside the capillary. A plasma temperature around 1.4 eV has been measured, that depends on the geometric properties and the operating conditions of the capillary
Focusing of high-brightness electron beams with active-plasma lenses
Plasma-based technology promises a tremendous reduction in size of accelerators used for research, medical, and industrial applications, making it possible to develop tabletop machines accessible for a broader scientific community. By overcoming current limits of conventional accelerators and pushing particles to larger and larger energies, the availability of strong and tunable focusing optics is mandatory also because plasma-accelerated beams usually have large angular divergences. In this regard, active-plasma lenses represent a compact and affordable tool to generate radially symmetric magnetic fields several orders of magnitude larger than conventional quadrupoles and solenoids. However, it has been recently proved that the focusing can be highly nonlinear and induce a dramatic emittance growth. Here, we present experimental results showing how these nonlinearities can be minimized and lensing improved. These achievements represent a major breakthrough toward the miniaturization of next-generation focusing devices
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