PrecisionspectroscopyoftheZeemansplittingsofthe 9 Be þ 2 2 S 1=2 hyperfinestructurefornuclearstructurestudies TakashiNakamura a ,MichiharuWada a, * ,KunihiroOkada b ,IchiroKatayama c , ShunsukeOhtani d ,H.A.Schuessler e a Atomic Physics Laboratory, RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan b Department of Physics, Sophia University, 7-1 Kioicho, Chiyoda, Tokyo 102-8554, Japan c Institute of Particle and Nuclear Studies (IPNS), High Energy Accelerator Research Organization (KEK), 1-1 Oho, Tsukuba, Ibaraki 305-0801, Japan d Institute for Laser Science, University of Electro-Communications, 1-5-1 Chofugaoka, Chofu, Tokyo 182-8585, Japan e Department of Physics, Texas A&M University, College Station, TX 77843, USA Received7October2001;receivedinrevisedform7October2001;accepted25February2002 Abstract A precision measurement for the hyperfine Zeeman splittings of 9 Be þ ions, trapped and laser cooled in a linear combinediontrapwasperformedbyusinglaser–rfdoubleandtripleresonancemethods.Theaccuraciesof10 9 forthe nuclear spin flip transitions and of 10 8 for the electron spin flip transitions were achieved at an arbitrary value of strongmagneticfieldof 0.47T.Thisenablesustodeterminethehyperfineconstant A andtheratioofnuclear g-factor toelectronic g-factorwithaccuraciesof10 9 and10 7 ,respectively. Toshowthewiderapplicabilityofourmethod,theparticularstrengthofthemagneticfieldwherethenuclearspin fliptransitionisindependentofthemagneticfieldstrengthwasintensionallynotused.Theconfiningfieldsofthelinear combinedtraphavetheadvantageofsimpleandefficientconcentrationoftheionsintothepotentialminimumatthe centerofthetrap,whenlasercoolingofthestoredionsisperformed.Thefeasibilityofsingleionspectroscopywasalso demonstratedand,whenfullyimplementedwillfacilitatetheon-linestudyofshortlivedisotopes,whichcanonlybe producedinminutenumbers. Ó 2002PublishedbyElsevierScienceB.V. PACS: 32.10.Fn;32.60.+i;32.10.Dk;32.30.Bv Keywords: Hyperfine structure;Linearcombinedtrap;Bohr–Weisskopfeffect;Doubleresonancespectroscopy 1. Introduction Inthepast,precisionmeasurementsofZeeman splittings of the ground state hyperfine structure (HFS)oftrappedionshavebeenperformedmainly by aiming towards the development of frequency standards.Incontrastwehaveproposedtoapply 1May2002 OpticsCommunications205(2002)329–336 www.elsevier.com/locate/optcom * Correspondingauthor.Tel.:+81-48-467-9487;fax:+81-48- 462-4644. E-mail address: mw@riken.go.jp(M.Wada). 0030-4018/02/$-seefrontmatter Ó 2002PublishedbyElsevierScienceB.V. PII:S0030-4018(02)01259-2