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Amorphous carbon thin films: Mechanisms of hydrogen incorporationduring magnetron sputtering and consequences for the secondary electronemission
/ Adame, C F ; Alves, E (Lisbon, IST) ; Barradas, N P (Lisbon, IST) ; Costa Pinto, P (CERN) ; Delaup, Y (CERN) ; Ferreira, I M M ; Neupert, H (CERN) ; Himmerlich, M (CERN) ; Pfeiffer, S (CERN) ; Rimoldi, M (CERN) et al.
Amorphous carbon (a-C) films, having low secondary electron yield (SEY), are usedat CERN to suppress electron multipacting in the beam pipes of particleaccelerators. It was already demonstrated that hydrogen impurities increase theSEY of a-C films. [...]
2023 - 14 p.
- Published in : J. Vac. Sci. Technol. A 41 (2023) 043412
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The Role of Hydrogen Incorporation into Amorphous Carbon Films in the Change of the Secondary Electron Yield
/ Bundaleski, Nenad (New Lisbon U.) ; Adame, Carolina F. (New Lisbon U.) ; Alves, Eduardo (IST, Lisbon ; Lisbon U.) ; Barradas, Nuno P. (IST, Lisbon ; Lisbon U.) ; Cerqueira, Maria F. (Minho U.) ; Deuermeier, Jonas (New Lisbon U.) ; Delaup, Yorick ; Ferraria, Ana M. (IST, Lisbon) ; Ferreira, Isabel M.M. (New Lisbon U.) ; Neupert, Holger (CERN) et al.
Over the last few years, there has been increasing interest in the use of amorphous carbon thin films with low secondary electron yield (SEY) to mitigate electron multipacting in particle accelerators and RF devices. Previous works found that the SEY increases with the amount of incorporated hydrogen and correlates with the Tauc gap. [...]
2023 - 20 p.
- Published in : Int. J. Molecular Sci. 24 (2023) 12999
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Cd implantation in α-MoO3: An atomic scale study
/ Gerami, Adeleh Mokhles (IPM, Tehran ; CERN) ; Heiniger-Schell, Juliana (CERN ; Duisburg-Essen U.) ; da Silva, E Lora (Porto U.) ; Costa, Messias S (Para U.) ; Costa, Cleidilane S (Para U.) ; Monteiro, João G (IST/ITN, Lisbon) ; Pires, José J (Lisbon, CFTP) ; Pereira, Daniela R (Lisbon, ISEL) ; Díaz-Guerra, Carlos (Madrid U.) ; Carbonari, Artur W (IPEN, Sao Paulo) et al.
Lamellar α-MoO3 crystals were implanted with low fluence of radioactive Cd111m ions at ISOLDE-CERN. Subsequently, we have probed the interaction of the Cd impurity in the lattice with native point defects, such as oxygen vacancies, as a function of annealing temperature using the time differential perturbed angular correlations nanoscopic technique. [...]
2023 - 15 p.
- Published in : Phys. Rev. Mater. 7 (2023) 033603
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Carbon Coatings with Low Secondary Electron Yield
/ Taborelli, M (CERN) ; Colaux, J (Namur U.) ; Costa Pinto, P (CERN) ; Calatroni, S (CERN) ; Chiggiato, P (CERN) ; Edwards, P (CERN) ; Letant-Delrieux, D (CERN) ; Lucas, S (Namur U.) ; Neupert, H (CERN) ; Vollenberg, W (CERN) et al.
Carbon thin films for electron cloud mitigation and anti-multipacting applications have been prepared by dc magnetron sputtering in both neon and argon discharge gases and by plasma enhanced chemical vapour deposition (PECVD) using acetylene. The thin films have been characterized using Secondary Electron Yield (SEY) measurements, Scanning Electron Microscopy (SEM), Nuclear Reaction Analysis (NRA) and X-ray Photoelectron Spectroscopy (XPS). [...]
CERN-ATS-2012-287.-
Geneva : CERN, 2013 - 31 p.
- Published in : Vacuum 98 (2013) 29-36
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In : 14th Joint Vacuum Conference - 12th European Vacuum Conference - 11th Annual Meeting of the German Vacuum Society - 19th Croatian - Slovenian Vacuum Meeting, Dubrovnik, Croatia, 4 - 8 Jun 2012, pp.29-36
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The impact of H$_2$ and N$_2$ on the material properties and secondary electron yield of sputtered amorphous carbon films for anti-multipacting applications
/ Fernández, H Moreno (CERN) ; Himmerlich, M (CERN) ; Costa Pinto, P (CERN) ; Coroa, J (CERN) ; Sousa, D (Nova U., Lisboa) ; Baris, A (CERN) ; Taborelli, M (CERN)
Amorphous carbon thin films were prepared by direct current hollow cathode sputter deposition in Ar discharge
with the injection of small amounts of H$_2$ and/or N$_2$. The influence of these additives on the film properties with
particular focus on the application as a coating for electron cloud mitigation in particle accelerators is characterized by optical spectroscopy, X-ray photoelectron spectroscopy, and secondary electron yield (SEY) measurements. [...]
2021 - 10 p.
- Published in : Appl. Surf. Sci. 542 (2021) 148552
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Type-I Seesaw with eV-Scale Neutrinos
/ Branco, G.C. (Lisbon, CFTP) ; Penedo, J.T. (Lisbon, CFTP) ; Pereira, Pedro M.F. (Lisbon, CFTP) ; Rebelo, M.N. (Lisbon, CFTP ; CERN) ; Silva-Marcos, J.I. (Lisbon, CFTP)
We consider seesaw type-I models including at least one (mostly-)sterile neutrino with mass at the eV scale. Three distinct situations are found, where the presence of light extra neutrinos is naturally justified by an approximately conserved lepton number symmetry. [...]
arXiv:1912.05875.-
2020-07-23 - 43 p.
- Published in : JHEP 2007 (2020) 164
Article from SCOAP3: PDF; Fulltext: PDF;
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Estimation of Sputtering Damages on a Magnetron H- Ion Source Induced by Cs+ and H+ Ions
/ Pereira, H (CERN) ; Lettry, J (CERN) ; Alessi, J (Brookhaven) ; Kalvas, t (Jyvaskyla U.)
An H− ion source is being developed for CERN’s Linac4 accelerator. A beam current requirement of 80 mA and a reliability above 99% during 1 year with 3 month uninterrupted operation periods are mandatory. [...]
CERN-ATS-2013-017.-
Geneva : CERN, 2013 - 9 p.
- Published in : AIP Conf. Proc. 1515 (2013) 81-88
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In : 3rd International Symposium on Negative Ions, Beams and Sources, Jyväskylä, Finland, 3 - 7 Sep 2012, pp.81-88
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Gravitational waves in massive gravity theories: waveforms, fluxes and constraints from extreme-mass-ratio mergers
/ Cardoso, Vitor (Lisbon, CENTRA ; Lisbon, IST ; CERN) ; Castro, Gonçalo (Lisbon, CENTRA ; Lisbon, IST) ; Maselli, Andrea (Lisbon, CENTRA ; Lisbon, IST)
Is the graviton massless? This problem was addressed in the literature at a phenomenological level, using modified dispersion relations for gravitational waves, in linearized calculations around flat space. Here, we perform a detailed analysis of the gravitational waveform produced when a small particle plunges or inspirals into a large non-spinning black hole. [...]
arXiv:1809.00673.-
2018-12-18 - 6 p.
- Published in : Phys. Rev. Lett. 121 (2018) 251103
Fulltext: PDF; Fulltext from Publisher: PDF;
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