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At the SPARC_LAB facility of INFN-LNF we are installing a transport lines for ultra-short electron bunches and another for ultra-intense laser pulses, generated by the SPARC photo-injector and by the FLAME laser in a synchronized fashion at the tens of fs level, to co-propagate inside a hydrogen filled glass capillary, in order to perform acceleration of the electron bunch by a plasma wave driven by the laser pulse. The main aim of this experiment is to demonstrate that a high brightness electron beam can be accelerated by a plasma wave without any significant degradation of its quality. Motivations of the technical choices are made and expected performances are reported.

We report on the development of radiation and electron sources based on laser-plasma acceleration for biomedical and nuclear applications, using both the table top TW laser at ILIL and the 220 TW FLAME laser system at LNF. We use the ILIL laser to produce wakefield electrons in a self-focusing dominated regime in a mm scale gas-jet to generate large, uniform beams of MeV electrons for electron radiography and radiobiology applications. This acceleration regime is described in detail and key parameters are given to establish reproducible and reliable operation of this source. We use the FLAME laser to drive laser-plasma acceleration in a cm-scale gas target to obtain stable production of &gt, 100 MeV range electrons to drive a Thomson scattering ɣ-ray source for nuclear applications.

Electrons with a linear energy/momentum dispersion are called massless Dirac electrons and represent the low-energy excitations in exotic materials such as graphene and topological insulators. Dirac electrons are characterized by notable properties such as a high mobility, a tunable density and, in topological insulators, a protection against backscattering through the spin–momentum locking mechanism. All those properties make graphene and topological insulators appealing for plasmonics applications. However, Dirac electrons are expected to present also a strong nonlinear optical behaviour. This should mirror in phenomena such as electromagnetic-induced transparency and harmonic generation. Here we demonstrate that in Bi2Se3 topological insulator, an electromagnetic-induced transparency is achieved under the application of a strong terahertz electric field. This effect, concomitantly determined by harmonic generation and charge-mobility reduction, is exclusively related to the presence of Dirac electron at the surface of Bi2Se3, and opens the road towards tunable terahertz nonlinear optical devices based on topological insulator materials., The terahertz response of topological insulator surface states, in which relativistic electrons are protected from backscattering, possesses potential optic and plasmonic applications. Here, the authors demonstrate a nonlinear absorption response of Bi2Se3 to terahertz electric fields.

Sub-picosecond, high-brightness electron bunch trains are routinely produced at SPARC-LAB via the velocity bunching technique. Such bunch trains can be used to drive multi-color Free Electron Lasers (FELs) and plasma wake field accelerators. In this paper we present recent results at SPARC-LAB on the generation of such beams, highlighting the key points of our scheme. We will discuss also the on-going machine upgrades to allow driving FELs with plasma accelerated beams or with short electron pulses at an increased energy.

A short period undulator (1.4 cm) has been designed for the SPARC-FEL test facility and has been realized in collaboration with KYMA Srl. It has been installed on the undulator line at SPARC. The undulator, operating in a delta like mode, has been used as radiator in a segmented configuration. The first stage being provided by the five undulators of the SPARC FEL source "old" chain, with period 2.8 cm. The KYMA undulator has a quatrefoil structure, a high magnetic field homogeneity and focuses both in vertical and radial directions. The two sections, namely the bunching and radiating parts, are arranged in such a way that the second is adjusted on a harmonic of the first. Laser action occurring in the second part, is due to the bunching acquired in the first. Simulations of the temporal and spectral profiles in different electron beam operating conditions are reported, as well as the evolution of the longitudinal phase space. The agreement with the experimental results is discussed The importance of this experiment is at least threefold: 1) It proves that the segmented undulator can successfully be operated 2) It proves that the laser emission in the last undulator is entirely due to the bunching mechanism, being no second harmonic signal present in the first segment 3) Encourages various improvements of the configuration itself, as e.g. the use of a further undulator with variable magnetic field configuration in order to obtain a laser field with adjustable polarization. © 2015 SPIE.

The six-dimensional beam phase space at the exit of a photoinjector can be completely characterized by means of an RF deflector and a dispersive system. In this paper we summarize the main features of the use of an RF deflector to measure aspects of the longitudinal and transverse phase space in an ultra-short electron beam. In particular we illustrate these measurements through the simulation of experiments currently under development at the SPARC photoinjector. We also discuss the design procedure followed to design the RF deflector for SPARC. This device is a five-cell structure operating on the π mode at 2.856 GHz. Finally, we report and discuss the cold-test measurement results on a full scale aluminum prototype.

We present the experimental evidence of the generation of coherent and statistically stable Free-Electron Laser (FEL) two color radiation obtained by seeding an electron double peaked beam in time and energy with a single peaked laser pulse. The FEL radiation presents two neat spectral lines, with time delay, frequency separation and relative intensity that can be accurately controlled. The analysis of the emission shows a temporal coherence and regularity in frequency significantly enhanced with respect to the Self Amplified Spontaneous Emission (SASE). © 2015 SPIE.

The ultra-short electron beams, produced through the velocity bunching compression technique at the SPARC_LAB test Facility (Frascati, Italy), are used to produce Coherent Transition Radiation in the terahertz (THz) range. This paper reports on the main features of this THz source, which have a spectral coverage up to 5 THz, a pulse duration down to 100 fs, and an energy per pulse on the order of tens of μJ. These figures of merits open the possibility to apply this source for nonlinear and THz pump-probe experiments in Solid-State Physics and material science.

International audience; The DAΦNE Φ-factory at INFN-LNF has been upgraded in the second half of 2007 with the scope of testing a recently proposed scheme of crab waist collisions. New vacuum chambers and permanent quadrupole magnets have been designed, fabricated and installed to realize the new configuration. The ring injection systems have been also modified with the installation of new stripline fast injection kickers. Moreover the old bellows have been substituted by the new ones and all ion clearing electrodes in the electron ring have been removed. In the talk we describe the new layout as well as several experimental results obtained during the new run.

In order to characterize and optimize the beam emittance compensation scheme [L. Serafini and J. B. Rosenzweig, Phys. Rev. E 55, 7565 (1997)] of the Sorgente Pulsata Autoamplificata di Radiazione Coerente project [D. Alesini et al., Nucl. Instrum. Methods Phys. Res. A 507, 345 (2003)] high brightness preinjector a system to accurately measure the beam rms emittance evolution downstream of the rf gun has been developed. Since in a space charge dominated beam the quadrupole-scan method is not applicable, a movable emittance measurement device has been built based on the pepper-pot technique. The device consists of a double system of horizontal and vertical slit arrays and a downstream screen, all installed on a longitudinally movable support equipped with bellows and spanning the ≈1.2m long drift space between gun and first accelerating section. The system allows the measuring of the beam rms emittance all along the spanned region so as to accurately reconstruct its evolution along the beam trajectory. More...

The control system for LISA (INFN-LNF Frascati) is based on relatively short but very fast parallel buses. The high bandwidth available makes it possible to build a system where a central VME processor controls all data exchange in both directions. Data are continuously and autonomously read by the central processor from the hardware interfaces and stored in a central memory. Commands are passed in the opposite direction under operator control. Measurements of data flow rates show this system to be viable for small machines.