First Experiments with the Laser Ion Source and Trap (LIST) Daniel Fink 15th EN-STI Students’ Coffee, CERN EN Department, CERN, Geneva and University of Heidelberg 24/1/2013 Daniel Fink - EN-STI Students' Coffee - CERN

Daniel Fink - EN-STI Students' Coffee - CERN Content ISOLDE: CERN’s playground for modern alchemists Motivation: reduction of isobaric contamination Introduction to resonance ionization laser ion source (RILIS) Principle of the laser ion source and trap (LIST) LIST on-line run 2011 LIST on-line run 2012 Summary 24/1/2013 Daniel Fink - EN-STI Students' Coffee - CERN

ISOLDE: CERN’s Playground for Modern Alchemists? Lead 82 79 Gold Alchemist, England 1576 N 24/1/2013 Daniel Fink - EN-STI Students' Coffee - CERN

ISOLDE: CERN’s Playground for Modern Alchemists? New nuclear reactions Asymmetric fission, etc. Nuclear medicine Nucleosynthesis in the universe PET, α-therapy, etc. Supernovae, neutron stars, … Size and shape of exotic nuclei + Laser spectroscopy + Biophysics + Solid state physics … and much more Halo nucleus 11B N 24/1/2013 Daniel Fink - EN-STI Students' Coffee - CERN

The Isotope Separator On-Line (ISOL) Process Production Extraction/Ionization Effusion Ionization Isotope Separation Post acceleration or to Experiment ISOLTRAP Q/A MINIBALL 24/1/2013 Daniel Fink - EN-STI Students' Coffee - CERN

Daniel Fink - EN-STI Students' Coffee - CERN The ISOLDE Target Unit Transfer line and ion source 1.4 GeV Protons Ions Ion source Target 1.4 GeV Protons 24/1/2013 Daniel Fink - EN-STI Students' Coffee - CERN

Daniel Fink - EN-STI Students' Coffee - CERN The ISOLDE Laboratory Radioactive laboratory Target area Separator magnets 1.4 GeV protons RILIS Control room New hall extension Experimental hall 24/1/2013 Daniel Fink - EN-STI Students' Coffee - CERN

Motivation: Reduction of Isobaric Contamination Example: isobaric contamination in a 78Ni ion beam: 78Ni 0.2 s 78Cu 0.34 s 78Zn 1.5 s 78Ga 5.5 s 78Ge 88 m 78As 1.5 h 78Se N=50 Z=28 1 102 104 srelative Fission of U with 1 Gev protons 10-2 Q/A A = 78 Remove Ti-Foil 24/1/2013 Daniel Fink - EN-STI Students' Coffee - CERN

Motivation: Reduction of Isobaric Contamination Remove Ti-Foil Nonselective surface ionization in hot cavity Strong isobaric contamination might harm or prevent experiments 24/1/2013 Daniel Fink - EN-STI Students' Coffee - CERN

Resonance Ionization Laser Ion Source (RILIS) Element unique RILIS schemes: Principle of RILIS: AIS IP Rydberg state E2 E1 Resonant laser photons on atoms + Stepwise excitation of e- E0 Very efficient and element selective ionization! A panoramic view of the RILIS laser setup: Change polonium to genera 24/1/2013 Daniel Fink - EN-STI Students' Coffee - CERN

Scheme of RILIS at ISOLDE RILIS Dye Laser System GPS/HRS Target & Ion Source RILIS Ti:Sa Laser System pA – meter Faraday cup… SHG/THG/FHG l – meter Ti:Sa 2 Dye 2 SHG Narrowband Dye THG Dye 1 Ti:Sa 1 Ti:Sa 3 (narrowband) Nd:YAG 2 Nd:YAG 1 LabVIEW based DAQ 24/1/2013 Daniel Fink - EN-STI Students' Coffee - CERN

Isobaric contamination in RILIS beams Remove Ti-Foil Nonselective surface ionization in hot cavity Strong isobaric contamination might harm or prevent experiments 24/1/2013 Daniel Fink - EN-STI Students' Coffee - CERN

Isobaric contamination in RILIS beams Remove Ti-Foil Strong increase of ions of interest Higher selectivity but isobaric contaminants remain in beam 24/1/2013 Daniel Fink - EN-STI Students' Coffee - CERN

Isobaric contamination in RILIS beams high field gradient Remove Ti-Foil Deflection of surface ions by electrostatic deflection Increased energy spread of laser ions due to high extraction field gradient Ineffective mass separation and poor transport efficiency 24/1/2013 Daniel Fink - EN-STI Students' Coffee - CERN

Principle of Laser Ion Source and Trap (LIST) Remove Ti-Foil Deflection of surface ions by electrostatic deflection High selectivity due to laser ionization outside hot cavity Transverse rf-trapping field guides ions towards extraction region 24/1/2013 Daniel Fink - EN-STI Students' Coffee - CERN

Daniel Fink - EN-STI Students' Coffee - CERN LIST Target Assembly LIST device: Necassary target modifications: Radiation hard components Stable support Automatic rf-connector Stable line- and target holder Transducer box LIST target unit: Proposal: K. Blaum et al., NIMB 204 (2003) 331 1 cm Add slide for idea of LIST targets protons 24/1/2013 Daniel Fink - EN-STI Students' Coffee - CERN

Daniel Fink - EN-STI Students' Coffee - CERN Robot Test 24/1/2013 Daniel Fink - EN-STI Students' Coffee - CERN

Daniel Fink - EN-STI Students' Coffee - CERN LIST Setup at ISOLDE RILIS cabin High voltage cage 1. 285 nm (UV) Glass fiber Nd:YAG Dye 1 SHG Repeller voltage 2. 552 nm Rf-generator Dye 2 Remote control 3. 532 nm Mg RILIS setup ̴ 20m ISOLDE hall Target area GPS + + + Separator magnet Picture of Windmill + + 60 keV Detectors: tape station, Faraday cup, MCP, Windmill 24/1/2013 Daniel Fink - EN-STI Students' Coffee - CERN

LIST Run 2011: Proof of Principle 1. Suppression of stable surface ions: 2. Reliability and robustness: Suppression: > 3000 3. Suppression of radioactive ions: 4. Laser ionization of radiactive ions: Add suppression factors 𝐈𝐂𝐈𝐨𝐧 𝐠𝐮𝐢𝐝𝐞 𝐈𝐂𝐋𝐈𝐒𝐓 > 𝟏𝟔𝟎𝟎 𝟏 𝐈𝐂𝐈𝐨𝐧 𝐠𝐮𝐢𝐝𝐞 𝐈𝐂𝐋𝐈𝐒𝐓 ≈𝟓0 Effective suppression of surface ions but with lower laser ionization efficiency. 24/1/2013 Daniel Fink - EN-STI Students' Coffee - CERN

LIST On-Line Run 2012: First Physics RILIS schemes for Mg and Po: Goals of second LIST on-line run: Test of improved LIST design for higher efficiency Proof of principle with strongly outgassing UCx-target Provide highly purified beams of Mg and Po First real on-line applications of LIST at ISOLDE Improved LIST: UCx-target: α detector (Windmill, Leuven): Annular Si Si 216Po beam C-foils 20 mg/cm2 24/1/2013 Daniel Fink - EN-STI Students' Coffee - CERN

LIST Performance 2012: Efficiency and Suppression Scans of repeller voltage for different masses with β-detector: Suppression factor Overall suppression: 3 orders of magnitude But limits for certain isotopes Ion Guide vs. LIST: 30Mg: 𝐈𝐂𝐈𝐨𝐧 𝐠𝐮𝐢𝐝𝐞 𝐈𝐂𝐋𝐈𝐒𝐓 ≈𝟐0 208Po: 𝐈𝐂𝐈𝐨𝐧 𝐠𝐮𝐢𝐝𝐞 𝐈𝐂𝐋𝐈𝐒𝐓 ≈𝟐0 ( 2011: ≈𝟓0 ) Rearrange pictures. Move both to top and delete suppression number. Move ion guide vs LIST to bottom. Get rid of animations 24/1/2013 Daniel Fink - EN-STI Students' Coffee - CERN

Motivation: Laser Spectroscopy on Polonium Two measurement campaigns in 2007 and 2009 at ISOLDE/CERN Mean square radii of Po-isotopes among other elements: Po invisible due to Fr contamination: Refer to Bruce’s talk T. E. Cocolios & M.E. Seliverstov 2008 Several Po-isotopes remained unstudied due to strong Fr-contamination Using LIST to suppress Fr contamination in 2012 24/1/2013 Daniel Fink - EN-STI Students' Coffee - CERN

Polonium Spectroscopy: HFS and IS New Po-decay data on mass 219 Preliminary 216Po and 217Po in one measurement Direct measurement of IS of 216Po and 217Po Laser frequency offset, GHz 24/1/2013 Daniel Fink - EN-STI Students' Coffee - CERN

Daniel Fink - EN-STI Students' Coffee - CERN Summary LIST suppresses isobaric contaminants and improves selectivity of RILIS Proof of principle by 2011 on-line run: Suppression of > 1000 Ionization efficiency reduction by ≈50x (Mg) First real physics application in 2012: Suppression of > 1000, but limited by in-trap decay for certain isotopes Ionization efficiency reduction by ≈20x (Mg,Po) Laser spectroscopy of 217,219Po possible due to suppression of Fr by LIST Color code Ongoing characterization and improvement of LIST for physics in 2014. But … LIST is now an established ion source option for ISOLDE users 24/1/2013 Daniel Fink - EN-STI Students' Coffee - CERN

Acknowledgements Klaus Blaum, Richard Catherall, Thomas E. Cocolios ...and special thanks to the collaborators: Klaus Blaum, Richard Catherall, Thomas E. Cocolios Bernard Crepieux, Valentine Fedosseev, Alexander Gottberg, Nobuaki Imai, Tobias Kron, Matthias Kronberger, Bruce Marsh, Christoph Mattolat, Michael Moore, Sebastian Raeder, Sven Richter, Ralf Rossel, Sebastian Rothe, Maxim Seliverstov, Pekka Suominen, Marica Sjodin, Thierry Stora, Klaus Wendt, ... … and the whole IS456 collaboration Add Matthias, Thomas Cocolios and the IS 24/1/2013 Daniel Fink - EN-STI Students' Coffee - CERN

LIST Run 2011: First On-Line Test Mg scheme: Goals of LIST-run 2011: Proof of principle using Mg beams Characterizing LIST with radioactive isotopes Test of reliability and robustness Compare on-line- to off-line performance 24/1/2013 Daniel Fink - EN-STI Students' Coffee - CERN

Other Features: Easier Beam Tuning LIST mode IG mode Optimization in LIST mode much easier due to invisible proton impacts 24/1/2013 Daniel Fink - EN-STI Students' Coffee - CERN