The experience gained at CERN by the R&D for LINAC4 has been exported to medical and societal applications. With an innovative design of the Radio Frequecy Quadrupole (RFQ) at high frequencies, it is possible to build very com- pact structures, reproducible in industry and with the po- tential of full portability. ELISA (Experimental LInac for Surface Analysis) is a linear proton accelerator installed in the Science Gateway exhibition at CERN since October 2023. With a footprint of only 2×1 square meters, ELISA consists of an ion source, a one-meter-long RFQ working at 750 MHz and an analysing line dedicated to Particle Induced X-ray Emission (PIXE). The system can accelerate a proton beam (extracted from the source at 20 keV) up to an energy of 2 MeV. In this paper the ELISA source commissioning is presented, with a multi-parameter optimization performed both computationally and experimentally and the ultimate optimization of beam emittance at 20 keV, finally achieving the required brilliance of the source. High energy beam com- missioning will also be discussed, including RFQ voltage scan to study the transmission and characterize the ELISA RFQ.

The international e-e FCC study group aims to design an accelerator complex capable of injecting tunable and high charge electron-positron bunches into a collider with center-of-mass energy between 90 and 365 GeV. The injector complex will boost the initial energy of the electron-positron bunches using multiple linacs accelerating only electrons, only positrons, and both species up to the booster injection energy of 20 GeV. The requirements on the charge poses several challenges for the injector chain due to the important role played by the wakefield both in the longitudinal and in the transverse planes. We optimized the bunch length, the RF aperture of the accelerating cavities and the linacs’ layout to match the target parameters at the booster injection. In the longitudinal space we studied the impact of the wakefield on the final beam energy spread. In the transverse plane we minimized the emittance growth due to static errors along the different sections using several orbit steering algorithms, and we verified the impact of dynamic errors for the most promising designs. Furthermore, we designed an energy compressor to add flexibility to our design, and to widely scan the beam charge without strongly modifying the final bunch parameters. In this work we present a summary of these studies, which led to the linac design satisfying all the present requests for the injection to the booster. This current design is the basis for the injector complex cost estimation.

Picosecond-long x-ray pulses of moderate intensity and high repetition rate are highly sought after by the light source community, especially for time-resolved fine spectroscope analysis of matter in the linear response regime. As part of the upgrade of the Elettra 2.0, two radio frequency deflecting cavities will be installed to produce time-dependent orbit deflection to a few dedicated electron bunches with no effect on the regular bunches. This paper reports the radio frequency design of super-conducting deflecting crab cavities operating at 3.0 and 3.25 GHz. The design is based on a Quasi-waveguide Multicell Resonator (QMiR), firstly developed for Advanced Photon Source, which uses a trapped dipole mode for the crabbing of the bunches. QMiR has heavily loaded Higher Order Modes (HOMs) resulting in a sparse HOMs spectrum thus eliminating the need for HOMs couplers simplifying the cavity mechanical design. The detailed EM analysis, including HOM damping, particle tracking through the field, thermal & mechanical simulations are presented. This article reports both static and dynamic thermal loads and the conceptual design for "0 boil off" cavity cool down at 4.2 K or lower.

The Muon Cooling Complex is a crucial component of the future high-energy Muon Collider, where the ionization cooling technique is employed to reduce muon beam emittance by several orders of magnitude. This cooling technique necessitates the utilization of normal conducting, RF-accelerating cavities operating within a multi-Tesla magnetic field. This study illustrates the conceptual RF design of a 704 MHz copper cavity equipped with beryllium windows for the muon cooling demonstrator. Based on the specifications from the beam dynamics, frequency-domain eigenmode simulations have been conducted to calculate the primary RF figure of merits for the cavity. Subsequently, the cavity geometry has been optimized based on the results obtained from the eigenmode simulations. In a selected case, more advanced engineering analyses, including thermo-mechanical and Lorentz Force Detuning (LFD) simulations, have been performed to enable operation at gradients of up to 44 MV/m within strong solenoidal magnetic fields of up to 7.2 T.

The experience gained at CERN by the R&D for LINAC4 has been exported to medical and societal applications. With an innovative design of the Radio Frequecy Quadrupole (RFQ) at high frequencies, it is possible to build very com- pact structures, reproducible in industry and with the po- tential of full portability. ELISA (Experimental LInac for Surface Analysis) is a linear proton accelerator installed in the Science Gateway exhibition at CERN since October 2023. With a footprint of only 2×1 square meters, ELISA consists of an ion source, a one-meter-long RFQ working at 750 MHz and an analysing line dedicated to Particle Induced X-ray Emission (PIXE). The system can accelerate a proton beam (extracted from the source at 20 keV) up to an energy of 2 MeV. In this paper the ELISA source commissioning is presented, with a multi-parameter optimization performed both computationally and experimentally and the ultimate optimization of beam emittance at 20 keV, finally achieving the required brilliance of the source. High energy beam com- missioning will also be discussed, including RFQ voltage scan to study the transmission and characterize the ELISA RFQ.