Prat, EduardAbela, RafaelAiba, MasamitsuAlarcon, ArturoAlex, JurgenArbelo, YunieskiArrell, ChristopherArsov, VladimirBacellar, CamilaBeard, CarlBeaud, PaulBettoni, SimonaBiffiger, RogerBopp, MarkusBraun, Hans-HeinrichCalvi, MarcoCassar, ArianaCelcer, TineChergui, MajedChevtsov, PavelCirelli, ClaudioCitterio, AlessandroCraievich, PaoloDivall, Marta CsatariDax, AndreasDehler, MichaDeng, YunpeiDietrich, AlexanderDijkstal, PhilippDinapoli, RobertoDordevic, SladanaEbner, SimonEngeler, DanielErny, ChristianEsposito, VincentFerrari, EugenioFlechsig, UweFollath, RolfFrei, FranziskaGanter, RomainGarvey, TerenceGeng, ZheqiaoGobbo, AlexandreGough, ChristopherHauff, AndreasHauri, Christoph P.Hiller, NicoleHunziker, StephanHuppert, MartinIngold, GerhardIschebeck, RasmusJanousch, MarkusJohnson, Philip J. M.Johnson, Steven L.Juranic, PavleJurcevic, MarioKaiser, MaikKalt, RogerKeil, BorisKiselev, DanielaKittel, ChristophKnopp, GregorKoprek, WaldemarLaznovsky, MichaelLemke, Henrik T.Sancho, Daniel LlorenteLoehl, FlorianMalyzhenkov, AlexanderMancini, Giulia FulviaMankowsky, RomanMarcellini, FabioMarinkovic, GoranMartiel, IsabelleMaerki, FabianMilne, Christopher J.Mozzanica, AldoNass, KarolOrlandi, Gian LucaLoch, Cigdem OzkanParaliev, MartinPatterson, BrucePatthey, LucPedrini, BillPedrozzi, MarcoPradervand, ClaudeRadi, PeterRaguin, Jean-YvesRedford, SophieRehanek, JensReiche, SvenRivkin, LeonidRomann, AlbertSala, LeonardoSander, MathiasSchietinger, ThomasSchilcher, ThomasSchlott, VolkerSchmidt, ThomasSeidel, MikeStadler, MarkusStingelin, LukasSvetina, CristianTreyer, Daniel M.Trisorio, AlexandreVicario, CarloVoulot, DidierWrulich, AlbinZerdane, SerhaneZimoch, Elke2020-11-252020-11-252020-11-252020-11-0910.1038/s41566-020-00712-8https://infoscience.epfl.ch/handle/20.500.14299/173633WOS:000587990900001We present the first lasing results of SwissFEL, a hard X-ray free-electron laser (FEL) that recently came into operation at the Paul Scherrer Institute in Switzerland. SwissFEL is a very stable, compact and cost-effective X-ray FEL facility driven by a low-energy and ultra-low-emittance electron beam travelling through short-period undulators. It delivers stable hard X-ray FEL radiation at 1-A wavelength with pulse energies of more than 500 mu J, pulse durations of similar to 30 fs (root mean square) and spectral bandwidth below the per-mil level. Using special configurations, we have produced pulses shorter than 1 fs and, in a different set-up, broadband radiation with an unprecedented bandwidth of similar to 2%. The extremely small emittance demonstrated at SwissFEL paves the way for even more compact and affordable hard X-ray FELs, potentially boosting the number of facilities worldwide and thereby expanding the population of the scientific community that has access to X-ray FEL radiation.OpticsPhysics, AppliedPhysicsstatistical propertiesradiationsingletext::journal::journal article::research article