The Frascati Beam Test Facility

From 2004 the Frascati Beam Test Facility (BTF) in the DAFNE accelerator complex provides to the external user up to 1E10 electrons per bunch or up to 10E9 positrons per bunch to develop their detectors. After an upgrade program terminated in 2020 of the beam test facility a description of the status and available beam lines will be done.Comment: Talk presented at the International Workshop on Future Linear Colliders (LCWS 2023), 15-19 May 2023. C23-05-15.

The machine protection system for the ELI-NP gamma beam system

The new Gamma Beam System (GBS) of the ELI-NPproject [1], currently under installation in Magurele (RO)by INFN, as part of EuroGammas consortium, can providegamma rays that open new possibilities for nuclear photonicsand nuclear physics.ELI-NP gamma rays are produced by Compton back-scattering to get monochromaticity (0,1% bandwidth), highflux (1013photons), tunable direction and energy up to19.5 MeV. Such gamma beam is obtained when a high-intensity laser collides a high-brightness electron beam withenergies up to740 MeV, a repetition rate of100 Hz, withtrains of 32 bunches within the same RF bucket.An advanced Machine Protection System (MPS) has beendeveloped, in order to ensure proper operation for this chal-lenging facility. The MPS operates on different layers of thecontrol system and is interfaced with all its sub-systems. Forinstance, it comprises different kind of beam loss monitors(based on Cherenkov optical fiber), hall probes, fast currenttransformer together with BPMs, and an embedded systembased on FPGA with distributed I/O over EtherCAT, to mon-itor vacuum and RF systems [2], which require fast responseto be interlocked within one RF pulse

Intense terahertz pulses from SPARC-LAB coherent radiation source

The linac-based Terahertz source at the SPARC_LAB test facility is able to gene rate highly intense Terahertz broadband pulses via coherent transition radiation (CTR) from high brightness electron beams. The THz pulse duration is typically down to 100 fs RMS and can be tuned through the electron bunch duration and shaping. The measured stored energy in a single THz pulse has reached 40 μ J, which corresponds to a peak electric field of 1.6 MV/cm at the THz focus. Here we present the main features, in particular spatial and sp ectral distributions and energy characterizations of the SPARC_LAB THz source, which is very competitive for investigations in Condensed Matter, as well as a valid tool for electron beam longitudinal diagnostics

Deposition and characterization of niobium films for SRF cavity application

Niobium coated copper cavities are an interesting alternative to bulk niobium ones for Superconducting Radio Frequency (SRF) applications to particle accelerators. The magnetron sputtering is the technology developed at CERN for depositing niobium Alms and applied over the past twenty years. Unfortunately, the observed degradation of the quality factor with increasing cavity voltage, not completely understood, prevents the use of this technology in future large accelerators designed to work at gradients higher than 30 MWm, with quality factors of the order of 1010 (or higher). At the beginning of the new millennium some new deposition techniques have been proposed to overcome the difficulties encountered with the sputtering technique. This paper compares the properties of niobium films obtained with the magnetron sputtering and with a cathodic arc deposition in ultra-high vacuum (UHVCA). The UHVCA-produced Nb Alms have structural and transport properties closer to the bulk ones, providing a promising alternative for niobium coated, highvoltage and high-Q copper RF cavities, with respect to the standard magnetron sputtering technique. Preliminary results and possible approaches to whole cavity UHVCA coating will be presented and discussed

Beam manipulation for resonant plasma wakefield acceleration

Plasma-based acceleration has already proved the ability to reach ultra-high accelerating gradients. However the step towards the realization of a plasma-based accelerator still requires some e ff ort to guarantee high brightness beams, stability and reliability. A significant improvement in the efficiency of PWFA has been demonstrated so far accelerating a witness bunch in the wake of a higher charge driver bunch. The transformer ratio, therefore the energy transfer from the driver to the witness beam, can be increased by resonantly exciting the plasma with a properly pre-shaped drive electron beam. Theoretical and experimental studies of beam manipulation for resonant PWFA will be presented her

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

Wake fields effects in dielectric capillary

Plasma wake-field acceleration experiments are performed at the SPARC LAB test facility by using a gas-filled capillary plasma source composed of a dielectric capillary. The electron can reach GeV energy in a few centimeters, with an accelerating gradient orders of magnitude larger than provided by conventional techniques. In this acceleration scheme, wake fields produced by passing electron beams through dielectric structures can determine a strong beam instability that represents an important hurdle towards the capability to focus high-current electron beams in the transverse plane. For these reasons, the estimation of the transverse wakefield amplitudes assumes a fundamental role in the implementation of the plasma wake-field acceleration. In this work, it presented a study to investigate which parameters affect the wake-field formation inside a cylindrical dielectric structure, both the capillary dimensions and the beam parameters, and it is introduced a quantitative evaluation of the longitudinal and transverse electric fields

The SPARC-LAB Thomson source commissioning

Abstract The SPARC_LAB Thomson source is presently under commissioning at LNF. An electron beam of energy between 30-150 MeV collides head-on with the laser pulse provided by the Ti:Sapphire laser FLAME, characterized in this phase by a length of 6 ps FWHM and by an energy ranging between 1 and 5 J. The key features of this system are the wide range of tunability of the X- rays yield energy, i.e. 20-500 keV, and the availability of a coupled quadrupole and solenoid focusing system, allowing to reach an electron beam size of 10-20 microns at the interaction point. The experimental results obtained in the February 2014 shifts are presented

Performance of scintillating tiles with direct silicon-photomultiplier (SiPM) readout for application to large area detectors

The light yield, the time resolution and the efficiency of different types of scintillating tiles with direct Silicon Photomultiplier readout and instrumented with a customised front-end electronics have been measured at the Beam Test Facility of Laboratori Nazionali di Frascati and several test stands. The results obtained on minimum ionising particles with different detector configurations are presented. A time resolution of the order of 300 ps, a light yield of more than 230 photo-electrons, and an efficiency better than 99.8% are obtained with ∼ 225 cm2 large area tiles. This technology is suitable for a wide range of applications in high-energy physics, in particular for large area muon and timing detectors