Recent advances in laser spectroscopy Iain Moore University of - PowerPoint PPT Presentation

Recent advances in laser spectroscopy Iain Moore University of Jyväskylä, Finland I.D. Moore, NUSTAR Week 2013, Helsinki, Finland

Outline of talk  A nuclear fingerprint in the atomic spectrum  Collinear laser spectroscopy & extensions  Commissioning of the new IGISOL-4 facility  In-source and in-jet resonance ionization  Laser developments and a look to the future I.D. Moore, NUSTAR Week 2013, Helsinki, Finland

A nuclear fingerprint in the atomic spectrum Y + 20 μ eV Model Independent Model Dependent (measured) (inferred) Isotope shift δ <r 2 > Sizes Dynamic / static Isomer shift δ <r 2 > deformations Q s Hyperfine Splitting Spins Single / few particle configurations μ I.D. Moore, NUSTAR Week 2013, Helsinki, Finland

Probing the deformation of nuclei Quadrupole δ <r 2 > 40 Zr deformation parameter Radius of spherical nucleus of same volume R θ z R = R 0 ( 1 + β 2 Y 2,0 ( θ , φ )) N=50 shell closure I.D. Moore, NUSTAR Week 2013, Helsinki, Finland

Laser spectroscopy of radioisotopes - status Fr (TRIUMF – collinear) Recent work mostly by in-source (ISOLDE – CRIS) Resonance Ionization Spectroscopy At (RIS) Tl Au Ac Recent work mostly by collinear laser spectroscopy Z Rb (TRIUMF) Before 1995 Z (J. Billowes and P. Campbell, Cd (ISOLDE) J. Phys. G 21 (1995) 707) Between 1995 and 2010 ( B. Cheal and K.T. Flanagan, J. Phys. G 37 (2010) 113101 ) Mn (JYFL/ISOLDE) K (ISOLDE) Since 2010 N I.D. Moore, NUSTAR Week 2013, Helsinki, Finland

Workhorse: Collinear Laser Spectroscopy (CLS) CW tunable laser beam (~1mW) Fast ion beam Applied Doppler tuning voltage Charge exchange (if required) PMT rf cooler Doppler broadened profile Ion source ν ν 0 W. Nörtershäuser et al., Phys. Rev. Lett. 102 (2009) 062503 I.D. Moore, NUSTAR Week 2013, Helsinki, Finland

CLS on cooled and bunched beams 31 Ga Accumulate Ungated End plate potential Photon counts Release 50 ms bunching Reacceleration potential z Gated (64-70 μ s) Charge exchange Background due Ion counts to scattered light Applied Doppler tuning voltage PMT Background suppression 50 ms/6 μ s = × 10 4 E. Mané et al., PRC 84 (2011) 024303 I.D. Moore, NUSTAR Week 2013, Helsinki, Finland

Optical manipulation in the RFQ • J =0 → J =1 gives μ , Q , δ <r 2 > but not I • Access to more accessible/efficient transitions IGISOL-3 layout • New elements to study (eg. Nb, Mn at JYFL) Tunable pulsed laser B. Cheal et al., Phys. Rev. Lett. 102 (2009) 222501 I.D. Moore, NUSTAR Week 2013, Helsinki, Finland

Ultra-pure beams: Ion Resonance Ionization Multiple pulsed lasers (resonantly ionize 1 + → 2 + ) Currently planned for 2014 at JYFL: Proposal B. Cheal Accumulate Potential 1+ ions 2+ ions (kicked away) (of single A , Z ) Release Cooler axis Time of flight analysis • Ultra pure beam of single A and Z • No contaminant will have m / q selected by magnet and m /(2 q) selected by TOF (or other device) I.D. Moore, NUSTAR Week 2013, Helsinki, Finland

High frequency intensity modulation on bunched atom beams • Intensity modulation of the laser light suppresses hyperfine pumping in CLS of atoms • Demonstrated at TRIUMF on neutron deficient 206,205,204 Fr • Immediately transferable to facilities, eg LaSpec 40 cm ( ~ 3 µ s transit time) A. Voss et al., Phys. Rev. Lett. 111 (2013) 122501 Talk by A. Voss (JYFL/TRIUMF) @ 15:30 I.D. Moore, NUSTAR Week 2013, Helsinki, Finland

The new IGISOL-4 from K=130 MeV facility cyclotron https://www.jyu.fi/fysiikka/en/research/accelerator/igisol Off-line ion sources: (discharge, carbon cluster…) K=30 MeV Laser transport cyclotron for optical manipulation/ IRIS Laser ionization in-source/in-jet Collinear laser spectroscopy Decay spectroscopy Mass spectrometry Fast extraction ( ~ 1 ms) • & post-trap spectroscopy • Chemically non-selective I.D. Moore, NUSTAR Week 2013, Helsinki, Finland

Commissioning of the collinear beam line (2013) Laser spectroscopy of neutron rich Mo fission fragments ( 102-106,108 Mo) F.C. Charlwood et al., Phys. Lett. B 674 (2009) 23 4d 4 5s 6 D 1/2 (11783 cm -1 ) → 4d 4 5p 6 F 1/2 (45853 cm -1 ) 104 Mo 104 Mo Laser hut IGISOL-4 IGISOL-3 Penning traps April 2013 July 2008 RFQ-buncher 107 Mo IGISOL-4 April 2013 • First “commissioning run” Fission yields 2-3 × higher than IG-3 • 107 Mo measured for the first time • Further optimisation planned • I.D. Moore, NUSTAR Week 2013, Helsinki, Finland

Resonant laser ionization (spectroscopy) ionization of excitation of non-resonant Rydberg-states ionization auto-ionizing states extraction ~6 eV field or IP (5-9 eV) collisional σ Ι ~ 10 -17 cm 2 σ Ι ~ 10 -15 cm 2 ionization higher excited states energy HOT CAVITY first E 1 excited • ISOLDE, TRIUMF, GANIL, state ORNL, PNPI, ALTO, (SPES) σ R : ~ 10 -12 cm 2 ground GAS CELL state E 0 • Leuven, JYFL, (PALIS) 0 eV SELECTIVITY & EFFICIENCY I.D. Moore, NUSTAR Week 2013, Helsinki, Finland

Dual-chamber gas cell (Leuven/JYFL) 2013: 58 Cu ( τ ½ =3.2s) Ar/He Laser beams from gas Longitudinal purifier Beam from Cyclotron Target Ionization chamber Separation of stopping and laser 11% ionization volume improves: Ion Collector 2% 17% • Laser ionization efficiency at high cyclotron beam current 223 Ra ( τ 1/2 =11.4 d) α -recoil source • Increasing selectivity Exit hole efficiencies Ø 0.5 – 1 mm (collection of non-neutral ions) SPIG Yu. Kudryavtsev et al., NIM B 267 (2009) 2908 M. Reponen, I.D. Moore et al., NIMB (2013), doi:10.1016/j.nimb.2013.05.061 I.D. Moore, NUSTAR Week 2013, Helsinki, Finland

RIS in-source vs. collinear laser spectroscopy IN-SOURCE (RIS) COLLINEAR (FAST BEAMS) Selective process High resolution Low lifetimes, low yields (<1 ion/s) Scanning voltage, not frequency High detection efficiency Limited by detection method Poor resolution (100-1000× < CLS) Beams of some 10 3 ions/s 6 - 800 6 - 6 - 722 β 700 68 Cu 1 + 1 + 0 β 600 68 Cu 500 Counts 400 1 + (g.s.) 300 200 100 0 10000 15000 20000 25000 Relative Frequency (MHz) P. Vingerhoets et al., PRC 82 (2010) 064311 I. Stefanescu et al., PRL 98 (2007) 122701 I.D. Moore, NUSTAR Week 2013, Helsinki, Finland

Gas jet laser ionization – a tool for the future a quest for PURE radioactive ion beams • → (the Laser Ion Source ``Trap´´) I.D. Moore et al., AIP Conf. Proc. 831 (2006) 511 • an optimal environment for spectroscopy (reduced temperature and pressure) 2 P 3/2 F j 2 P 1/2 2 S 1/2 F i F=J+I I.D. Moore, NUSTAR Week 2013, Helsinki, Finland

First free jet ions in LIST geometry at JYFL 0,12 Ref. cell 0,09 FWHM = 1.8(2) GHz 0,06 0,03 0,00 Ion signal (arb. u.) 63 Cu Gas cell 4000 FWHM = 6.7(3) GHz 3000 He, 180 mbar 2000 1000 0 300 Gas jet (LIST) FWHM = 3.9(2) GHz 200 V jet ~1040 m/s 100 Employ special nozzles • 0 -20 -10 0 10 20 • Laser linewidth dominated ν - 915 423.95 (GHz) I.D. Moore et al., NIMB (2013), doi:10.1016/j.nimb.2013.06.036 I.D. Moore, NUSTAR Week 2013, Helsinki, Finland

Collinear resonance ionization spectroscopy Radioactive Charge exchange cell bunched ion beam Doppler tuning from ISOLDE voltage applied UHV interaction Stable beam region from off line MCP: ion ion source detection Ge detectors Laser beam PMT: fluorescence Si detectors detection Decay spectroscopy 202,203,204,205,207,211 Fr 218,219, 220,221,229,231 Fr Talk by K. Flanagan (Manchester) @ 16:25 I.D. Moore, NUSTAR Week 2013, Helsinki, Finland

Development of narrow-band pulsed Ti:sapphire lasers Output to experiment ( <20 MHz, 3W @10kHz) Injection-locked pulsed Nd-YAG Ti:sa cavity Glass plate pump laser fast optical isolator Attenuator piezo TEM LaseLock digital HV d = n λ cw PSD fast switched photodiode Ti:sa crystal PD signal amplifier Mode- in matching telescope single mode fiber 1-150 mW Sirah Matisse TS cw-Ti:sa • Similar developments at RIKEN/Nagoya and TRIUMF ~ 60 kHz linewidth • RESIST Joint Research Activity for ENSAR 2 I.D. Moore, NUSTAR Week 2013, Helsinki, Finland

Applications: high resolution spectroscopy Spectroscopy of 229 Th Spectroscopy of 227 Ac 1.5 GHz total width 227 Ac 46347.0cm -1 1.5 GHz total width 424.7 nm J 1 =3/2 22 801.1 cm -1 3.5 GHz total width 877.16 nm /2 = 438.58 nm 6d7s 2 J 0 =3/2 V. Sonnenschein et al., J. Phys. B 45 (2012) 165005 I.D. Moore, NUSTAR Week 2013, Helsinki, Finland

Looking towards the future Towards Superheavy Elements A variety of techniques are used to probe the regions of interest Further away from stability New & future facilities Refractory Elements around Shell Closures • Becola (MSU) • TRIGASPEC (Mainz) • HELIOS@S3, GANIL Clusters and Halos • LaSpec at FAIR I.D. Moore, NUSTAR Week 2013, Helsinki, Finland

Thank you