INFN/LNL, Legnaro (PD), Italy
Università degli Studi di Padova, Padova, Italy
The I.FAST collaboration aims at pushing the performance of particle accelerators by developing sustainable innovative technologies. Among its goals, the development of thin film-coated copper elliptical accelerating cavities covers both the optimization of the manufacturing of seamless substrates and the development of functional coatings able to conform to the 3D cavity geometry while delivering the needed performance. For the latter, the optimization of the deposition recipe is central to a successful outcome. The work presented here focuses on the deposition of Nb₃Sn films on flat, small copper samples. The films are deposited via DCMS from a planar stoichiometric Nb₃Sn commercial target. The results of the film characterization are presented here. The observed dependencies between the film properties and, in particular, Tc(90%-10%) = (17.9±0.1)K is reported for Nb₃Sn on sapphire and Tc(90%-10%) = (16.9±0.2)K for Nb₃Sn on copper with a 30 micron thick niobium buffer layer.
Università degli Studi di Padova, Padova, Italy
LNF-INFN, Frascati, Italy
INFN/LNL, Legnaro (PD), Italy
Univ. degli Studi di Padova, Padova, Italy
INFN-Salerno, Baronissi, Salerno, Italy
Fermilab, Batavia, Illinois, USA
The search for dark matter is now looking at ALPs (axion-like particles) as a very promising candidate to understand our universe. Within this framework, we explore the possibility to use NbTi thin film coatings on Cu resonating cavities to investigate the presence of axions in the range of 35-45 µeV mass by coupling the axion to a very strong magnetic field inside the cavity, causing its conversion to a photon which is subsequently detected. In this work the chemical treatments and DC magnetron sputtering details of the preparation of 9 GHz, 7 GHz, and 3.9 GHz resonant cavities and their quality factor measurements at different applied magnetic fields are presented.
INFN/LNL, Legnaro (PD), Italy
CEA-IRFU, Gif-sur-Yvette, France
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
Cockcroft Institute, Warrington, Cheshire, United Kingdom
CEA-DRF-IRFU, France
Piccoli, Noale (VE), Italy
INFN/LASA, Segrate (MI), Italy
INFN- Sez. di Padova, Padova, Italy
The University of Liverpool, Liverpool, United Kingdom
Lancaster University, Lancaster, United Kingdom
Université Paris-Saclay, CNRS/IN2P3, IJCLab, Orsay, France
University Siegen, Siegen, Germany
HZB, Berlin, Germany
University of Siegen, Siegen, Germany
Cockcroft Institute, Lancaster University, Lancaster, United Kingdom
Riga Technical University, Riga, Latvia
HZDR, Dresden, Germany
Slovak Academy of Sciences, Institute of Electrical Engineering, Bratislava, Slovak Republic
IEE, Bratislava, Slovak Republic
STFC/DL, Daresbury, Warrington, Cheshire, United Kingdom
JLab, Newport News, Virginia, USA
Thin-film cavities with higher Tc superconductors (SC) than Nb promise to move the operating temperature from 2 to 4.5 K with savings 3 orders of magnitude in cryogenic power consumption. Several European labs are coordinating their efforts to obtain a first 1.3 GHz cavity prototype through the I.FAST collaboration and other informal collaborations with CERN and DESY. R&D covers the entire production chain. In particular, new production techniques of seamless Copper and Niobium elliptical cavities via additive manufacturing are studied and evaluated. New acid-free polishing techniques to reduce surface roughness in a more sustainable way such as plasma electropolishing and metallographic polishing have been tested. Optimization of coating parameters of higher Tc SC than Nb (Nb₃Sn, V₃Si, NbTiN) via PVD and multilayer via ALD are on the way. Finally, rapid heat treatments such as Flash Lamp Annealing and Laser Annealing are used to avoid or reduce Cu diffusion in the SC film. The development and characterization of SC coatings is done on planar samples, 6 GHz cavities, choke cavities, QPR and 1.3 GHz cavities. This work presents the progress status of these coordinated efforts.
