Liquid and solid lasers for optimum performance of the Resonance Ionization Laser Ion Source at ISOLDE/CERN

Liquid and solid lasers for optimum performance of the Resonance Ionization Laser Ion Source at ISOLDE/CERN V.N. Fedosseev, CERN, EN department Workshop on Low-Energy Radioactive Isotope Beam (RIB) Production by In-Gas Laser Ionization for Decay Spectroscopy at RIKEN, 10-11 December 2012, RIKEN-Wako

Outline The ISOLDE facility at CERN Ionization in a hot cavity Evolution of RILIS lasers Dual dye-ti:sa laser system of RILIS New modes of RILIS operation RILIS operation in 2012 Dual narrow-band RILIS Outlook Workshop announcement

ISOLDE isotope separator on-line facility 1-1.4 GeVp 2 µa Single charge: Surface Plasma RILIS ECR

Laser ionization in a Hot Metal Cavity First RIBs produced in 1990-1991 at PNPI (Gatchina, Leningrad district): at CERN: Yb, Nd, Ho Ho - off-line -on-line Yb, Tm, Sn, Li Yb -off-line on-line

Hot Cavity Laser Ion Source Efficiency: ε = P P Ionisation Ionisation + P Effusion Lasers located ~ 18 m away ε = ν rep ν rep ε ion εion 2dv + 3L 2 TARGET Selectivity = Laser Ionization Efficiency Surface Ionization Efficiency => depends on the ionization potentials of isobar atoms ε laser = 2% - 30% ε surface > 5% - alkalies = 0.1% -2% - In, Ga, Ba, lanthanides < 0.1% - others

RILIS at ISOLDE Facility

RILIS at ISOLDE-PSB + Ion beam lines + Mass separator + Laser system Proton beam Extraction Electrode 60 kv CVL lasers: ν rep =11.000 Hz Oscillator + 2 amplifiers 2-3 dye lasers with amplifiers, nonlinear crystals BBO: Target Laser beams + + Ionizer DC Target - Ion Source Unit Target Installed in 1993 P total Cu 75 P dye 8 P2ω 2W W W P3ω 0. 2 W

RILIS setup with Copper vapor lasers Constructed in 90-s, in operation till 2009 Copper vapor laser: High peak power (short pulse); high repetition rate, good beam quality (unstable resonator) Dye lasers: Wide tuning range, ionization schemes with up to 3 steps

RILIS operation since 1994 Annually increasing demand for RILIS beams Feasible hours of operation limit reached in 2002 Increase requires greater reliability and a larger laser installation RILIS UPGRADE 2500 demand Operation per year (h) 2000 1500 1000 500 Limit reached for existing laser resources 0 1994 1996 1998 2000 2002 2004 2006 2008 2010

The 3 stages of RILIS Upgrade 1 The pump laser upgrade 1 : Change from copper vapour laser (CVL) to commercial Nd:YAG laser Aim: Maintain or improve the dye laser performance whilst increasing the reliability of the overall system. 2 The dye laser upgrade: 3 New state of the art dye lasers to replace the original dye lasers Aim: Improve the dye laser performance, ease of use and reliability, make full use of the capabilities of the new pump laser. 3 Install an independent and complementary Ti:Sabased RILIS laser setup 2,3 : 2 pump lasers and 3 Ti:Sa lasers plus harmonic generation units Aim: Extend the tuning range of the RILIS setup to enable access to the large number of ionization schemes developed for Ti:Salasers. Reduce switching time between elements to allow for more condensed scheduling of RILIS runs. 2008 2009 2010 2011 2012 Additional on-going developments Improve monitoring and automation of the RILIS parameters Implement machine protection and alert systems to enable on-call operation Improve the selectivity of RILIS through ion source developments 1 The ISOLDE RILIS pump laser upgrade and the LARIS Laboratory B. Marsh et al: Hyperfine Interactions, Volume 196, Issue 1-3, pp. 129-141 (2010) 2 A complementary laser system for ISOLDE RILIS S Rothe et al: Journal of Physics: Conference Series 312 (2011) 052020 3 Upgrade of the RILIS at ISOLDE: New lasers and new ion beams V. Fedosseev et al: Rev. Sci. Instrum. 83, 02A903 (2012)

1 -Pump Laser upgrade CVL Replacement of Copper VaporLasers by Solid-State Lasers SSL 15 ns @ 11 khz 8 ns @ 10 khz Green Beams Green Beams 75 W (+28 W) 45 W @ 511 nm @ 532 nm Yellow Beams 35 W @ 578 nm 2 hr start up time Varying power output over time The ISOLDE RILIS pump laser upgrade and the LARIS Laboratory B. Marsh et al: Hyperfine Interactions, Volume 196, Issue 1-3, pp. 129-141 (2010) UV Beam 20 W @ 355 nm IR Beam 45 W @ 1064 nm 30 min start up time Reliable long term power output

Second step of RILIS upgrade CREDO dye lasers made by Sirah GmbH installed in Feb/Mar 2010 New Dye Lasers installed Optimized for 10 khz EdgeWave pump Accept both 355 and 532 pumping beams Equipped with FCU (up to 2W of UV) Upgrade of the RILIS at ISOLDE: New lasers and new ion beams V. Fedosseev et al: Rev. Sci. Instrum. 83, 02A903 (2012)

Dye vs. Ti:Sa lasers Dye Ti:Sa Active Medium > 10 different dyes =1 Ti:sapphire crystal condition of aggregation liquid solid-state Tuning range 540 850 nm 680 980 nm Power upto 15 W upto5 W Pulse duration 8 ns 50 ns Power stability decrease during operation stable Synchronization optical delay lines q-switch, pump power Maintenance renew dye solutions ~ none 10.0 5.0 2.0 1.0 0.5 0.2 0.1 Dye 3x Ti:Sa 3x Dye 4x Ti:Sa Ti:Sa 2x Dye 2x Ti:Sa 200 300 400 500 600 700 800 900 wavelength nm efficiency (%) 35 30 25 20 15 10 5 0 Ti:Sa Dye 550 600 650 700 750 800 850 900 950 wavelength (nm)

Dual RILIS Concept Nd:YAG Dye 2 SHG λ meter 10 khz Master clock Delay generator Dye1 THG Narrowband Dye RILIS Dye Laser System GPS/HRS Nd:YAG RILIS Ti:Sa Laser System Ti:Sa 1 SHG/THG/FHG Ti:Sa 2 Ti:Sa 3 Target & Ion Source Faraday cup LabVIEW based DAQ λ meter pa meter

The RILIS Ti:Sa lasers Pump laser: Nd:YAG (532 nm), Photonics Industries Internattional Repetition rate: 10 khz Pulse length: 180 ns Power: 60 W lassing efficiency (%) 30 25 20 15 10 5 700 750 800 850 900 950 wavelength (nm) SP4440 SP4444 SP0000 SP1000 SP1111 SP1110 A complementary laser system for ISOLDE RILIS S Rothe et al: Journal of Physics: Conference Series 312 (2011) 052020 Change of mirror sets in resonator No amplifier yet available No ageing 100 mm Ti:Sa lasers: Line width: 5 GHz Pulse length: 30-50 ns Wavelength tuning range: Fundamental (ω) 690-940nm (5 W) 2nd harmonic (2ω) 345-470nm (1 W) 3rd harmonic (3ω) 230-310nm (150 mw) 4 th harmonic (2w) 205-235nm (50 mw) 6 resonator mirror sets cover the Ti:Sa range

Third step of RILIS upgrade Addition of Ti:Sapphire lasers Ti:Sa 1 Ti:Sa 2 3ω, 4ω 3ω, 4ω Ti:Sa 3 Dye Laser 3 Nd:YAG 2 Nd:YAG 3 Nd:YAG 1 Dye Laser 2 Dye Laser 3 Frequency conversion unit

3 steps of RILIS laser upgrade completed 1) Pump laser replacement Nd:YAG Dye 2 SHG 3) Ti:Sa laser installation 2) Dye laser replacement RILIS Dye Laser System λ meter Master clock Dye 1 THG Dye 3 SHG Delay Generator GPS/HRS Nd:YAG Ti:Sa 1 RILIS Ti:Sa Laser System Target & Ion Source Ti:Sa 2 SHG FHG Ion beam to Users Ti:Sa 3 λ meter

The complete RILIS Dye + Ti:Sa system Sirah dye lasers with 2nd harmonic generation and UV pumping option Dye laser 3rd harmonic generator Narrow band dye laser with computer controlled grating and etalon for high resolution spectroscopy or isomer selectivity Edgewave Nd:YAG laser for dye pumping or non resonant ionization Photonics Industries Nd:YAG pump laser for the Ti:Sa lasers RILIS cabin layout has been redesigned to accommodate the new lasers 3 Ti:Sa lasers Harmonic generation unit for Ti:Sa system

New modes of operation The Dual RILIS Prerequisite for dual operation: Temporal synchronization pulses of the two laser systems 100W Nd:YAGlaser is available for non-resonant ionization in Ti:Sa only schemes Mixed schemes dye and Ti:Sa are exchangeable Highest efficiencies New elements Unique for laser ion sources Backup solution Keep one dye set up for future, use Ti:Sa instead Reduction in down time

RILIS setup requirements Element Dye laser schemes Ti:Sa schemes Step 1 Step 2 Step 3 Step 1 Step 2 Step 3 Setting time* Efficiency days λ1, nm Dye λ2, nm Dye/YAG λ3, nm Dye/YAG off-line λ1, nm Fundamental λ2, nm Fundamental λ3, nm TiSa/YAG 4Be 12Mg 13Al 20Ca 21Sc 25Mn 27Co 28Ni 29Cu 30Zn 31Ga 39Y 47Ag 48Cd 49In 50Sn 51Sb 60Nd 62Sm 65Tb 3 2 2 2 2 3 2 3 2 3 2 2 2 3 2 4 3 2 3 234.9 Pyridin 1 297.3 Rhod B 285.2 Rhod 6G 552.8 Fluorescein 27 532.1 YAG >7% 234.9 939.444 285.2 855.639 552.8 532.1 YAG 10% 309.3 Rhod B 532.1 YAG 20% 309.3 532.1 308.2 Rhod B 308.2 272.2? 532.1 YAG 327.4 Phenox 9 719.8 Pyridin 2? 532.1 YAG 279.8 Rhod 6G 628.3 DCM 635.8 DCM 304.4 Rhod B 544.5 Fluorescein 27 532.1 YAG 0.50% 15% 19% 422.7 845.346 Rhod B DCM 327.4 719.8 532.1 YAG 279.8 628.3 635.8 304.4 544.5 532.1 YAG >3.8% 305.1 Rhod B 611.1 Rhod B 748.2 Styr 8 >6% Dye Dye 748.2 TiSA 327.4 Phenox 9 287.9 Rhod 6G >7% 327.4 287.9 213.9 DCM 636.2 DCM 532.1 YAG 4.90% 213.9 855.428 636.2 Dye 532.1 YAG 287.4 Rhod 6G 532.1 YAG 21% 287.4 532.1 294.4 Pyrr 597 294.4 414.3 Styr 9 662.4 Phenox 9 510.6 YAG 414.3 662.4 510.6 YAG 328.1 Phenox 9 546.6 Fluorescein 27 532.1 YAG 328.1 546.6 532.1 YAG 14% 228.8 Pyridin 1 643.8 DCM 532.1 YAG 10.40% 228.8 915.208 643.8 Dye 532.1 YAG 303.9 Rhod B 532.1 YAG 303.9 532.1 325.6 Phenox 9 325.6 286.3 Rhod 6G 811.4 Styr 9 823.5 Styr 9 9% 286.3 858.9 811.4 TiSA 823.5 TiSA 217.6 Phenox 9 560.2 Rhod 6G 532.1 YAG 2.70% 217.6 560.2 532.1 YAG 588.8 Rhod B or Pyrr 596.9 Rhod B 596.9 588.8 596.9 596.9 597 600.4 Rhod B 675.2 Phenox 9 676.18 Phenox 9 600.4 675.2 676.18 579.6 Pyrr 597 551.7 Fluorescein 27 618.3 Rhod B 579.6 551.7 618.3 3 66Dy 2 625.9 DCM 607.5 Rhod B 532.1 YAG 20% 625.9 607.5 532.1 YAG 70Yb 2 555.6 Pyrr 567 581.0 Rhod 6G 581.0 Rhod 6G 15% 555.6 581.0 581.0 71Lu 573.7 Rhod 6G 642.5 DCM 643.5 DCM 451.9 903.8 460.7 921.4 79Au 80Hg 81Tl 82Pb 83Bi 84Po 85At 5 3 2 2 2 4 4 267.6 Coum 540A 306.5 DCM 673.9 Phenox 9 267.6 306.5 673.9 >3% 253.7 Styr 8 313.2 DCM 626 DCM 253.7 313.2 626 276.8 Rhod 110 532.1 YAG 283.3 Rhod 6G 600.2 Rhod B 532.1 YAG 306.8 Rhod B 555.2 Fluorescein 27 532.1 YAG 27% >3% 276.8 532.1 283.3 600.2 532.1 YAG 306.8 555.2 532.1 YAG 6% 255.8 Styr 8 843.4 Styr 9 532.1 YAG 255.8 767.403 843.4 TiSA 532.1 YAG 216.9 Phenox 9 795.4 Styr 9 532.1 YAG 216.9 867.6 795.4 TiSA 532.1 YAG 224.4 Phenox 9 793.2? Styr 9 532.1 YAG 224.4 897.6 793.2? TiSA 532.1 YAG

Double RILIS tuning curves 100000 10000 Power, mw 1000 100 TiSa FHG Dye THG 10 UV-pumped Dye SHG Dye SHG TiSa THG TiSa SHG UV-pumped Dye Fundamental Dye Fundamental TiSa fundamental 1 200 300 400 500 600 700 800 900 1000 Wavelength, nm

Example of RILIS setup Ni: Dye-Dye-TiSa 100000 10000 Step 1 Step 2 Step 3 Power, mw 1000 100 Higher power from TiSafor AIS transition 10 305 nm Dye SHG Ni 611 nm Dye fund 748 nm TiSa fund 1 200 300 400 500 600 700 800 900 1000 Wavelength, nm

Example of RILIS setup Ca: TiSa-Dye-Dye 100000 Step 2 Step 3 10000 Step 1 Power, mw 1000 100 Higher power from TiSa for Step 1 10 423 nm TiSa SHG Ca 586 nm Dye fund 654 nm Dye fund 1 200 300 400 500 600 700 800 900 1000 Wavelength, nm

Example of RILIS setup Mg: Dye-Dye-YAG 100000 Step 3 10000 Step 1 Step 2 Power, mw 1000 100 10 285 nm Dye SHG Mg 532 nm Nd:YAG SHG 553 nm Dye fund Only Dye scheme, TiSais setting up for next run (Po) 1 200 300 400 500 600 700 800 900 1000 Wavelength, nm

Example of RILIS setup Po: Dye-TiSa-YAG 100000 10000 Step 3 Step 2 Step 1 Power, mw 1000 100 Higher power from TiSa for Step 2 10 256 nm Dye THG Po 532 nm Nd:YAG SHG 843 nm TiSa fund 1 200 300 400 500 600 700 800 900 1000 Wavelength, nm

Example of RILIS setup At: Dye-TiSa-YAG 100000 Dye and TiSa exchangeable for Step 1 10000 Step 1 Step 3 Step 2 Power, mw 1000 100 Higher power from TiSa for Step 2 10 216 nm Dye THG At 532 nm Nd:YAG SHG 795 nm TiSa fund 1 200 300 400 500 600 700 800 900 1000 Wavelength, nm

Example of RILIS setup Au: TiSa-Dye-Dye 100000 Step 3 10000 Step 1 Step 2 Power, mw 1000 100 Higher power from TiSa for Step 1 10 268 nm TiSa THG 306 nm Dye SHG Au 674 nm Dye fund 1 200 300 400 500 600 700 800 900 1000 Wavelength, nm

Ca Ca Cd Cd Cd Ca Ca Be Be Mg Mg Po Po At At Au Zn Zn Cu Mn Mn Be Sm At Au Sm Sm Be Be Dy Dy Mg Mg Po Ag ISOLDE RILIS SCHEDULE 2012 RILIS runs in 2012 Sm At Au Sm Sm Be Be Dy Dy Mg Mg Po Ag Ca Ca Cd Cd Cd Ca Ca Be Be Mg Mg Po Po At At Au Zn Zn Cu Mn Mn Be

3000 2500 RILIS operation in 1994-2012 Ion beams of 13 elements were produced with RILIS in 2012 Laser ON time in 2012: 3000 h Expected by end of 2012 2916 h by 1 December 2000 Hours 1500 1000 500 0 1994 1996 1998 2000 2002 2004 2006 2008 2010 2012 Year Availability of two complementary laser systems (Dye and Ti:Sapphire) has ensured the increase of RILIS beam time in 2011-2012 Beam Sm 2 runs Ca 2 runs Cd At 2 runs Au 2 runs Be 3 runs Dy Mg 4 runs Po 2 runs Ag 2 runs Zn Cu Mn Planned 208 272 192 300 172 446 88 296 206 96 198 112 148 Real 212 359 253 345 262 278 111 378 206 113 124 69 208

The Dual Etalon Narrow Linewidth TiSa Addition of a thick etalon to the TiSacavity Remote dual etalon control, automatic optimization routine and feedback based frequency stabilization Reduction of line-width from >5 GHz <1GHz

Gold Isotopes Windmill Faraday Cup MR-TOF COUNTS Alpha energy, kev 1 st transition is difficult with dye laser (UV pump beam required) NB-TiSawas therefore advantageous: scanning stability with 3 rd harmonic was demonstrated MR-TOF, windmill and FC were used Beam time was extremely limited!

Astatine Isotopes: scans on both steps Windmill Faraday Cup MR-TOF Annular Si Si 197At beam NB -TiSa C-foils 20 µg/cm 2 NB -Dye laser ISOLDE Faraday cup Extensive Ionization scheme development was required

RILIS ion beams Ion beams of 31 elements are produced at ISOLDE with RILIS 31 elements ionized with RILIS 1 2 H 27 ionization scheme tested (dye or Ti:Sa) He 3 4 5 6 7 8 9 10 Li Be 25 RILIS ionization feasible 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 Recent new beams: Sm, Pr, At, Ca

RILIS in action

RILIS in action

Outlook, future developments Automated protection and remote monitoring of RILIS installation Improved RILIS schemes for the Dual RILIS system Extension of RILIS cabin Installation of a reference atomic beam unit at RILIS Fully motorized TiSa automatic tuning/optimization High beam quality laser for non resonant ionization Optimizing the LIST and other means of surface ion suppression

Acknowledgements BruceMarsh, Sebastian Rothe, MaricaSjödin, Daniel Fink CERN: STI Group of EN department Klaus Wendt, Ralf Rossel University of Mainz, Working group LARISSA Mainz, Germany Nobuaki Imai Visiting scientist at CERN Lars-Eric Berg, Olli Launila KTH Royal Institute of Technology Stockholm, Sweden Dmitri Fedorov, Maxim Seliverstov Petersburg Nuclear Physics Institute, Gatchina, Russia Knut and Alice Wallenberg Foundation

1 st Topical Workshop on Laser Based Particle Sources 20-22 February 2013 at CERN, Geneva, Switzerland https://indico.cern.ch/conferencedisplay.py?confid=212365