RILIS laser ion sources at ISOLDE/CERN V. Fedosseev CERN, EN-STI-LP
The proton beam and targets 50m PS Booster 0.6 GeV 1 GeV 1.4 GeV 3 10 13 ppp Uranium carbide, metal compounds, foils or molten metal targets Thickness ~ 50 200 g/cm 2 Temperature = 700 2000 K
The Ion Sources Resonance Surface Laser ionization ionization Electron impact ionization
RILIS at ISOLDE Facility RILIS
Hot Cavity Laser Ion Source Efficiency: P P Ionisation Ionisation P Effusion Lasers located ~ 18 m away HOT CAVITY rep rep ion ion 2dv 3L 2 TARGET Laser Ionization Efficiency Selectivity = Surface Ionization Efficiency => depends on the ionization potentials of isobar atoms laser = 2% - 30% surface > 5% - alkalies = 0.1% -2% - In, Ga, Ba, lanthanides < 0.1% - others
RILIS ion beams Ion beams of 29 elements are produced at RILIS elements available at ISOLDE LIS 1 2 H ionization scheme tested He 3 4 5 6 7 8 9 10 Li Be ionization scheme untested B C N O F Ne 11 12 13 14 15 16 17 18 Na Mg Al Si P S Cl Ar 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 K Ca Sc Ti V Cr Mn Fe Co Ni Cu Zn Ga Ge As Se Br Kr 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 Rb Sr Y Zr Nb Mo Tc Ru Rh Pd Ag Cd In Sn Sb Te I Xe 55 56 57 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 Cs Ba La Hf Ta W Re Os Ir Pt Au Hg Tl Pb Bi Po At Rn 87 88 89 104 105 106 107 108 109 110 111 112 Fr Ra Ac Rf Ha Sg Ns Hs Mt 58 59 60 61 62 63 64 65 66 67 68 69 70 71 Ce Pr Nd Pm Sm Eu Gd Tb Dy Ho Er Tm Yb Lu 90 91 92 93 94 95 96 97 98 99 100 101 102 103 Th Pa U Np Pu Am Cm Bk Cf Es Fm Md No Lr RILIS web page: http://isolde-project-rilis.web.cern.ch/isolde-project-rilis/intro/principle.html
Wavelength tuning range Laser power, mw 1200 1000 800 600 400 CVL-pumped dye laser tuning ranges Pyrr 546 0.25 g/l P(G)=7W Pyrr 567 0.20 g/l P(G)=7W Rhod 6G 0.5 g/l P(G)=7W Pyrr 597 0.58 g/l P(G)=7W R6G+ Rhod B P(G)=8W Rhod B 1 g/l P(G)=9.2W Rhod B 1 g/l P(Y)=9W Rhod 101 0.4 g/l P(Y)=8.5W DCM 0.6 g/l P(G)=12W Phenoxazone 9 0.5 g/l P(G)=8W Phenoxazone 9 0.5 g/l P(Y)=8.2W Rhod 700 fresh 0.5 g/l P(Y)=8.5W LDS 759 0.35 g/l P(Y)=8W Styryl 8 (LDS751) 0.5 g/l P(G)=7W LDS 765 0.33 g/l P(Y)=8W Styryl 9 0.5 g/l (Meth) P(Y)=8W Styryl 9 0.5 g/l (Meth) P(G)=11W Styryl 9 0.5 g/l (DMSO) P(Y)=8.5W Oxazine 4 0.29 g/l P(Y)=6.5W Oxazine 170 0.42g/l P(Y)=6.5W Nile Blue A (ISAN) 0.26g/l P(Y)=6.5W Rhod.110 0.44 g/l 200 0 5000 5500 6000 6500 7000 7500 8000 8500 9000 Wavelength, Angs.
Ionization schemes with CVL pumped dye lasers 2 CVL 1 Al (5.99 ev) Ca (6.11 ev) Ga (6.00 ev) In (5.79 ev) Tl (6.11 ev) 3 CVL 2 DL 3 DL Li (5.39 ev) Na (5.14 ev) Sr (5.69 ev) Ce (5.54 ev) Nd (5.52 ev) Sm (5.64 ev) Eu (5.67 ev) Gd (6.15 ev) Tb (5.86 ev) Dy (5.94 ev) Ho (6.02 ev) 1 DL 1 DL 2 1 DL 2 Tm (6.18 ev) Yb (6.25 ev) Lu (5.43 ev) Actinides 3 CVL 2 DL 1 3 DL Mg (7.65 ev) Sc (6.56 ev) Mn (7.43 ev) Co (7.86 ev) Ni (7.64 ev) Cu (7.73 ev) Y (6.22 ev) Ag (7.58 ev) Tc (7.28 ev) Sn (7.34 ev) Pb (7.42 ev) Bi (7.29 ev) 2 1 1 2 1 2 DL DL Cu (7.73 ev) Bi (7.29 ev) Be (9.32 ev) 1 1 3 DL 2 DL 1 1 3 DL Be (9.32 ev) Zn (9.39 ev) Cd (8.99 ev) Sb (8.61 ev) Po (8.42 ev) 3 DL 2 1 1 2 1 2 DL DL Hg (10.39 ev) Au (9.23 ev)
Application of different ion sources at ISOLDE H Ionized with ISOLDE RILIS 1 Ionized with surface ion source 2 3 4 Ionized with negative ion source 5 6 7 8 9 10 Li Be B C N O F Ne 11 12 Ionized with plasma ion source 13 14 15 16 17 18 Na Mg Al Si P S Cl Ar 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 K Ca Sc Ti V Cr Mn Fe Co Ni Cu Zn Ga Ge As Se Br Kr 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 Rb Sr Y Zr Nb Mo Tc Ru Rh Pd Ag Cd In Sn Sb Te I Xe 55 56 57 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 Cs Ba La Hf Ta W Re Os Ir Pt Au Hg Tl Pb Bi Po At Rn 87 88 89 104 105 106 107 108 109 110 111 112 Fr Ra Ac Rf Ha Sg Ns Hs Mt He 58 59 60 61 62 63 64 65 66 67 68 69 70 71 Ce Pr Nd Pm Sm Eu Gd Tb Dy Ho Er Tm Yb Lu 90 91 92 93 94 95 96 97 98 99 100 101 102 103 Th Pa U Np Pu Am Cm Bk Cf Es Fm Md No Lr
RILIS operation in 1994-2009 2500 SSL = 61% CVL = 39% Laser ON time in 2009: 2000 2148 h - total 1992 h - on-line Hours 1500 1000 500 0 1994 1996 1998 2000 2002 2004 2006 2008 In 2009 Nd:YAG lasers have been used for ALL 14 RILIS runs Year Be, Ga, Ag, Nd, Po, Mn, Mg, Po, Sn, Mg, Mn, Be, Zn, Ni
Upgrade of RILIS laser system Replacement of CVL by SSL Advantages: Better beam quality Stability of operation Spectral coverage UV-NIR without gaps Complications: New ionization schemes are needed (Mn, Au) Service by manufacturer only CVL: SSL: 15 installed years of in service 2008 for at ISOLDE Wavelength tuning range: Fundamental () 390-850 nm Wavelength tuning range: Wavelength tuning 2nd harmonic (2) range: Fundamental () 530 Fundamental - 850 () 210-4252nd 390 nm harmonic - 850 nm(2) 2652nd - 425 nm (2) 3rd harmonic 3rd 210-425 nm (3) (3) 2133rd - 265 harmonic (3) 213-265 nm 213-265 nm
New Nd:YAG lasers at ISOLDE RILIS Copper Vapor Lasers are replaced by Diode Pumped Solid State Nd:YAG Lasers Two lasers are available: one in use, second as a backup Main green beam Residual green beam UV beam Laser generates 3 beams at 10 khz: Main green beam 532nm, 70-80 W, 8 ns Residual green beam 532 nm, 12-28 W, 9 ns UV beam - 355 nm, 18-20 W, 11 ns
SSL implementation in RILIS room CVL amplifiers CVL oscillator Dye lasers SSL power supply and chiller CVL power supply SSL laser systems
Alignment of laser beams in space Optical bench for controlling the beam focalization and space overlap Movable Al mirror Serves for both separators
HRS channel Laser beam control New Focus picomotor mounts GPS channel Optical path to HRS source = 23 m Optical path to GPS source = 18 m
Laser beam transport Prism box in HRS zone 2 o wedge plate 40x40 mm prism Flipping Al mirror GPS laser window 735 mr/h 80000 counts/s
SSL use: enhancements and current limitations elements available at ISOLDE LIS 1 2 H ionization scheme tested He 3 4 5 6 7 8 9 10 Li Be ionization scheme untested B C N O F Ne Good example: Gallium 11 12 13 14 15 16 17 18 Na Mg Al Si P S Cl Ar ( used in 2008 and 2009 for COLLAPS) 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 K Ca Sc Ti V Cr Mn Fe Co Ni Cu Zn Ga Ge As Se Br Kr 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 Rb Sr Y Zr Nb Mo Tc Ru Rh Pd Ag Cd In Sn Sb Te I Xe Two dye lasers were applied at 1 st step of 55 56 57 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 Cs Ba La Hf Taexcitation W Re Os- >2x Ir improvement Pt Au Hg Tl Pb Bi Po At Rn More power could be delivered to HRS target at the 2 nd step of excitation 87 88 89 104 105 106 107 108 109 110 111 112 Fr Ra Ac Rf Ha Sg Ns Hs Mt 58 59 60 61 62 63 64 65 66 67 68 69 70 71 Ce Pr Nd Pm Sm Eu Gd Tb Dy Ho Er Tm Yb Lu 90 91 92 93 CVL 2 2 SSL 94 95 96 97 98 99 100 101 102 103 Th Pa U Np Pu Am Cm Bk Cf Es Fm Md No Lr 1 1 + + More green power 1 DL - 532 1nm dye DL pumping instead of 511 or 578 nm 2 2 54% are likely to benefit 46% from increased 46% final step power Most schemes are likely to Some schemes are no longer useable due to the 532 nm pump beam - lower final step efficiency or absorption cross section (Mn( Mn) - Need for a < 540 nm fundamental wavelength.
A new RILIS scheme for manganese - LARIS result Replacement of the scheme which uses the CVL green beam. Fortuitous Auto-ionizing transition at CVL wavelength AIS search at LARIS Outcome of RIS study of Mn at LARIS: Many new auto-ionizing states found Various promising Nd:YAG based schemes tested New scheme applied at RILIS Efficiency > 8 %
Isomer selectivity with RILIS 287.9 nm 0.2 0.18 0.16 m / g = 20 68gCu 68mCu 327.4 nm 68 Cu ~13 GHz 68gCu 68mCu Applied also at REX/MINIBALL Worlds first post accelerated isomer purified beams 68 Cu intensity (a.u.) 0.14 0.12 g / m = 20 0.1 0.08 0.06 0.04 0.02 0 30535 30535 30535 30535 30535 30536 30536 30536 Transition frequency (cm -1 ) Separation of the 3 -decaying isomers in 70 Cu K. Blaum, PRL vol. 92 (2004) 11 (3 - ) (6 - ) (3 - ) (1 + ) (1 + )
In-source laser spectroscopy Ei=8.42 ev 532.34 nm 538.89 nm 6p 3 7s 3 S 1 245.01 nm 511 nm CVL 6p 3 8p 6p 3 7p 843.39 nm 6p 3 7s 5 S 2 255.80 nm Techniques used to detect Po ions: detector with energy resolution detectors counter Faraday cap Annular Si Si 60 kev beam from ISOLDE Po 6s 2 6p 43 P 2 Ground state Spectral resolution is limited by Doppler width For transition at 843 nm D = 0.8 GHz
IS and HFS spectra of Polonium Even isotopes Odd isotopes (low spin)
RILIS after CVL-YAG transition More laser power -> higher ionization efficiency High stability of SSL power -> ion current stability much better Time from cold start of SSL to nominal operation ~ 30 min. No electromagnetic noise to experimental hall from RILIS New ionization scheme of Mn is developed CVLs can be removed from laser cabin SSL alignment and repair is possible only at EdgeWave UV power is limited by the optical resistance of harmonics crystals Efficiency of dye lasers is reduced due to shorter pump pulse Lifetime of dyes is reduced Operation of dye lasers and harmonics generators still requires continuous supervision by laser specialists
Next steps Dye Laser Upgrade One narrow (1 GHz) and two broadband (15 GHz) lasers are ordered Improve beam quality, especially for UV beams Increase harmonic generation efficiency Improve UV pumping performance Allegro (made by Sirah GmbH) dye laser with amplifier and frequency doubling unit pumped by EdgeWave laser running at 10kHz
Next steps Nd:YAG pumped Ti:Sa system An additional independent fully solid state RILIS laser system Reduction of the reliance on laser dyes. Better coverage of the IR and blue spectral ranges Dual RILIS system could enable simultaneous RILIS setup and operation. Pump laser: 2 X commercial PI Nd:YAG, 532 nm, 60 W at 10 khz Tunable lasers: 3 single sided UMz Ti:Sapphire lasers - frequency doubling, tripling and quadrupling - computerized temporal and spectral control, 3 GHz, 30 ns - specs: 3-5 W @ 690-980 nm, 1 W @ 350-470, 150 mw @ 200 315 nm Construction and purchasing of elements is started (Sebastian Rothe, PhD student in Mainz Uni and CERN) Space presently occupied by CVLs will be available for Ti:Sa system
Acknowledgments CERN, EN department Geneva, Switzerland Bruce Marsh Valentin Fedosseev Roberto Losito Sebastian Rothe Marica Sjödin K.U. Leuven, Instituut voor Kernen Stralingsfysica Leuven, Belgium Maxim Seliverstov Petersburg Nuclear Physics Institute, Gatchina, Russia Dima. Fedorov Yuri Volkov Pavel. Molkanov Anatoly Barzakh Victor Ivanov KTH Royal Institute of Technology Stockholm, Sweden Lars-Erik Berg Göran Tranströmer Thanks to Knut and Alice Wallenberg Foundation