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Placidi, M.

Publications and source records attributed to Placidi, M..

Cascading RF deflectors in compact beam spreader schemes

This study describes beam distribution schemes based on transverse electric field radio-frequency deflectors (RFD) as fast-switching devices and provides numerical relationships between their respective frequencies and phases. The adoption of compact transverse deflecting cavities represents an ideal solution for the design of high repetition rate ( > 1 MHz), compact beam distribution systems. While directly applicable to modern FEL facilities, this approach also provides opportunities for expanding existing beam delivery systems with additional experimental areas simultaneously feeding multiple beamlines. We derive the formalism for cascading RFDs by adopting the proper choice of deflector frequencies which can generate a large variety of beam switch yard topologies. Finally, we present for reference a potential application operating at an rf frequency of 325 MHz with the comparison of three possible distinct compact rf deflectors: a superconducting rf-dipole, a normal conducting rf-dipole, and a normal conducting 4-rod design.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗

Compact FEL-driven inverse compton scattering gamma-ray source

Many research and applications areas require photon sources capable of producing gamma-ray beams in the multi-MeV energy range with reasonably high fluxes and compact footprints. Besides industrial, nuclear physics and security applications, a considerable interest comes from the possibility to assess the state of conservation of cultural assets like statues, columns etc., via visualization and analysis techniques using high energy photon beams. Computed Tomography scans, widely adopted in medicine at lower photon energies, presently provide high quality three-dimensional imaging in industry and museums. We explore the feasibility of a compact source of quasi-monochromatic, multi-MeV gamma-rays based on Inverse Compton Scattering (ICS) from a high intensity ultra-violet (UV) beam generated in a free-electron laser by the electron beam itself. This scheme introduces a stronger relationship between the energy of the scattered photons and that of the electron beam, resulting in a device much more compact than a classic ICS for a given scattered energy. As a result, the same electron beam is used to produce gamma-rays in the 10–20 MeV range and UV radiation in the 10–15 eV range, in a ~4 × 22 m 2 footprint system.

43 PARTICLE ACCELERATORS↗

Compact Spreader Schemes

This paper describes beam distribution schemes adopting a novel implementation based on low amplitude vertical deflections combined with horizontal ones generated by Lambertson-type septum magnets. This scheme offers substantial compactness in the longitudinal layouts of the beam lines and increased flexibility for beam delivery of multiple beam lines on a shot-to-shot basis. Fast kickers (FK) or transverse electric field RF Deflectors (RFD) provide the low amplitude deflections. Initially proposed at the Stanford Linear Accelerator Center (SLAC) as tools for beam diagnostics and more recently adopted for multiline beam pattern schemes, RFDs offer repetition capabilities and a likely better amplitude reproducibility when compared to FKs, which, in turn, offer more modest financial involvements both in construction and operation. Both solutions represent an ideal approach for the design of compact beam distribution systems resulting in space and cost savings while preserving flexibility and beam quality.

43 PARTICLE ACCELERATORS↗