287 research outputs found
Beam loading assisted matching scheme for high quality plasma acceleration in linear regime
We propose and we numerically design a working point for beam driven plasma wakefield acceleration that allows us to preserve the witness quality. This working point is a new scheme where a low density driver generates a wakefield in linear regime and the witness transverse evolution is dominated by the beam loading effect. We derived optimal matching conditions to prevent the phase space degradation by means of a transverse envelope equation
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
A multicenter retrospective clinical study of CD5/CD10-negative chronic B cell leukemias.
CD5-negative chronic B cell lymphoproliferative disorders in leukemic phase (B-CLPD) are heterogeneous and relatively uncommon pathologies that often lack a histopathological definition because of the absence of accessible pathological tissue. We describe the clinical features and evolution-related variables of 156 patients with CD5/CD10-negative B-CLPD (median age 66 years, range 25-86). The median follow-up was 51 months (range 6-216), and overall 3- and 5-year survival was respectively 87 and 76%; 50 patients needed therapy at diagnosis, 56 during follow-up, and 50 remained untreated until the last control. A combined clinical, histological, cytomorphological, immunophenotypical, and cytogenetic diagnostic approach allowed the complete classification of only a minority of patients as being affected by splenic marginal zone or lymphoplasmacytic lymphoma; the majority of cases remained unclassifiable. Multivariate analysis showed that the clinicohematological variables adversely related to overall survival were serum LDH levels and age, whereas high serum LDH levels, hemoglobin levels of <11 g/dl, and splenomegaly related to treatment-free time (in "wait and see" cases); only splenomegaly related to time to progression (in treated patients). In conclusion, our retrospective study describes the clinical features and variables related to evolution in a large group of patients with CD5/CD10-negative chronic B-cell lymphoid leukemias and underlines the fact that a probable lymphoplasmacytic or marginal zone normal cell origin can be supposed in such leukemic forms, but never surely demonstrated
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
Multi-GeV Electron Spectrometer
The advance in laser plasma acceleration techniques pushes the regime of the
resulting accelerated particles to higher energies and intensities. In
particular the upcoming experiments with the FLAME laser at LNF will enter the
GeV regime with almost 1pC of electrons. From the current status of
understanding of the acceleration mechanism, relatively large angular and
energy spreads are expected. There is therefore the need to develop a device
capable to measure the energy of electrons over three orders of magnitude (few
MeV to few GeV) under still unknown angular divergences. Within the PlasmonX
experiment at LNF a spectrometer is being constructed to perform these
measurements. It is made of an electro-magnet and a screen made of
scintillating fibers for the measurement of the trajectories of the particles.
The large range of operation, the huge number of particles and the need to
focus the divergence present unprecedented challenges in the design and
construction of such a device. We will present the design considerations for
this spectrometer and the first results from a prototype.Comment: 7 pages, 6 figures, submitted to NIM
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
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
First single-shot and non-intercepting longitudinal bunch diagnostics for comb-like beam by means of Electro-Optic Sampling
At SPARC-LAB,we have installed an Electro-Optic Sampling(EOS)experiment for single shot,non-
destructive measurements of the longitudinal distribution charge of individual electron bunches.The
profile of the electron bunch field is electro-optically encoded into aTi:Sa laser, having 130fs(rms)pulse
length, directly derived from the photocathode's laser. The bunch profile information is spatially
retrieved,i.e.,the laser crosses with an angle of 30 degrees with respect to the normal to the surface of EO
crystal(ZnTe,GaP)and the bunch longitudinal profile is mapped into the laser's transverse profile.
In particular,we used the EOS for a single-shot direct visualization of the time profile of a comb-like
electron beam,consisting of two bunches, about 100fs(rms)long,sub-picosecond spaced with a total
charge of 160pC. The electro-optic measurements(done with both ZnTe and GaP crystals)have been
validated with both RF Deflector (RFD)and Michelson interferometer measurements
The THz Radiation Source at the SPARC Facility
The interest for Terahertz (THz) radiation is rapidly growing, both as it is a
powerful tool for investigating the behavior of matter at low energy, and as it allows for a number
of possible spectroscopic applications spanning from medical science to security. The linacdriven
THz source at the SPARC facility can deliver broadband THz pulses with femtosecond
shaping and can be used for electron beam diagnostics to fully reconstruct the longitudinal
charge distribution. Beyond this application, the possibility to store much more energy in a
single THz pulse than table-top sources renders the SPARC THz source very interesting for a
spectroscopic use. In addition, taking advantage from electron beam manipulation techniques,
high power, narrow-band THz radiation can be also generated. Those source characteristics
provide a unique chance to realize THz-pump/THz-probe spectroscopy, a technique practically
unexplored up to now
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