JRA-4: RESIST RESonance Ionization techniques for SeparaTors. Spokesperson: Iain Moore, JYFL Deputy: Valentin Fedosseev, CERN

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1 JRA-4: RESIST RESonance Ionization techniques for SeparaTors Spokesperson: Iain Moore, JYFL Deputy: Valentin Fedosseev, CERN

2 Objectives of RESIST We aim to refine the highly successful Resonance Ionization Laser Ion Source (RILIS), In-Gas Laser Ionization and Spectroscopy (IGLIS) and Laser Ion Source Trap (LIST) technologies, coupled to hot cavity or to gas cells at on-line facilities for the production and study of RIBs. Highest purity (isobaric and isomeric) will be obtained at ISOL and In-Flight facilities. Laser spectroscopic studies of exceptional sensitivity are anticipated using carefully optimized experimental environments. Work package number 12 Start Date or Starting Event March 1 st, 2015 Work package title JRA4 RESIST: RESonance laser Ionization techniques for SeparaTors Participant number Short name of participant JYU GANIL INFN CERN CNRS GSI KU Leuven JOGU Mainz Person-months/participant: Budget = 448 keuros

3 Description of work Task 1: Pre-LIST techniques to enhance ion beam purity (CERN) Subtask 1.1 (JGU Mainz, CERN) Reduction of secondary electron ionization processes pre-rf structure. Minimization of radioisotope deposition on RF structure leading to isotopedependent ionization mechanisms. Subtask 1.2 (KU Leuven, JYU) Optimization of laser-ionization geometry in the gas jet to minimize or even preclude photo-ion creation in the gas cell volume and minimizing the deposition of radioisotopes on the RF structure. Subtask 1.3 (GANIL, INFN) High temperature materials research for transfer line and laser ionization cavity for surface ion suppression.

4 Description of work Task 2: Advancements in efficiency, selectivity and spectral resolution (KU Leuven) Subtask 2.1 (GSI, KU Leuven, JYU, GANIL) Optimization of gas-cell coupling to a mass separator to target selectivity improvements of the future IGLIS technique at in-flight facilities. Subtask 2.2 (KU Leuven, JYU) Development of well-collimated, high Mach number gas jets Subtask 2.3 (JGU Mainz, CERN) Extensive excitation scheme development to optimize isobaric, isotopic and isomeric selectivity

5 Description of work Task 3: New concepts and development of laser technologies (Mainz) Subtask 3.1 (JGU Mainz, CERN) Optimization of automated wide range tunability of solid-state laser systems for atomic spectroscopy and scheme development. Subtask 3.2 (JYU, KU Leuven, CNRS) Generation of high power Fourier-limited laser radiation using injectionlocking techniques with a narrow bandwidth cw laser and pulsed dye amplification of a cw-diode laser radiation for in-jet spectroscopy. Subtask 3.3 (JGU Mainz, JYU, CERN, INFN) Investigation of new laser concepts for future RIB facilities as well as difference frequency mixing and Raman shifting to provide visible radiation from Ti:sapphire lasers.

6 Milestones & Deliverables 7 deliverables (reports) First (general task) report Month 12; 3 mid-term reports (Month 24); 3 final reports (Month 48) Milestone number Milestone name Due date (month) MS43 MS44 Reduction of hot cavity and gas jet radioisotope deposition on LIST rf structure Supersonic, high Mach number gas jet produced Means of verification 48 Clean RIBS produced with LIST (hot cavity and gas jet coupling) 48 Laser probing of jet velocity MS45 Ionization scheme development 24 Report at Annual Meeting MS46 MS58 MS59 Pulsed dye amplifier seeded by CW diode laser and injection-locked Ti:sapphire laser used in both off-line and on-line gas jet spectroscopy New high temperature transfer line material utilized for surface ion suppression Automated wide-range wavelength tunability for scheme development 36 Off-line experiment using the new laser 36 Off-line and on-line demonstration of surface ion reduction 24 Demonstration on a new element

7 Hot cavity LIST at ISOLDE Task 1 (1.1 - Optimising the LIST technique at ISOL facilities) Selectivity ~10 4 (surface ion suppression only) Efficiency loss 20 Outstanding problems: Recent publications Electron-impact ionization Condensation of radioisotopes Low efficiency

8 Developments for selectivity & efficiency A variety of improvements are planned.

9 Enhancement of ion beam purity Task 1 (1.3 - High temperature materials research for transfer line) Materials: R&D for new materials and electro-thermomechanical simulation for stability and performances Layout: R&D for new electrical layout connections for low voltage E-field optimization

10 High resolution spectroscopy in the LIST Tasks 2 & 3 (A mixture of sub-task developments) A novel new design: Perpendicular Illuminated LIST (PI-LIST) 99 Tc 32 GHz Ion Count Rate [cps] 98 Tc 97 Tc Features High suppression of ANY contaminants - background << 1cps SHG Frequency Tuning [GHz] HFS of Tc (nuclear moments) and 227 Ac (J assignments); publications in preparation! High resolution - experimental linewidth <<100 MHz High efficiency - sample sizes <10 11 atoms

11 Optimizing the ionization process Task 2 (2.3 Extensive excitation scheme development) Actinides: up to 4 open valence shells Missing information above ~40000 cm -1 Rydberg levels & AI states unknown Very limited spectroscopic information J= nm J= nm J=2 Th V. Sonnenschein, I.D. Moore et al., EPJ A 48 (2012) 52

12 Theoretical predictions for No (Z=102) 1 (MCDF): S.Fritzsche (2005) 2 (MCDF): S.Fritzsche (2005) 3 (IHFSCC): A.Borschevsky et al. (2007) 4 (RCC): V.A.Dzuba et al (2014) 5 (MCDF): Y.Liu et al. (2007) 6 (MCDF): P. Indelicato et al. (2007) 7 (extrapolation): J.Sugar (1974)

13 Wide-range automated scanning lasers Task 3 (3.1 - Automated tunable lasers for scheme development) A grating-based Ti:sapphire laser with second harmonic capability Features: Automized grating stage Intra-cavity doubling Closed loop feedback control system Flip-mirror for immediate switching between fundamental & second harmonic Properties Fundamental Second harmonic Spectral range 730 to 920 nm 370 to 420 nm Pulse energy up to 250 µj/pulse up to 50 µj/pulse Linewidth 7.5 GHz to be measured

14 Ultra-narrow linewidth pulsed lasers Task 3 (3.2 Generate high-power Fourier-limited laser radiation) Lock-in Amplifier PSD HV out Fast piezo mirror Output 4W 10kHz ns pulse width MHz linewidth pump laser pulse Fast-switched photodiode amplifier Input CW Ti:sa 1-10mW 100kHz linewidth nm Ti : sapphire crystal V. Sonnenschein, PhD thesis, University of Jyväskylä (2015)

15 Injection-locking spectroscopy Resonance ionization mass spectrometry of Pu isotopes using an injectionlocked Ti:sapphire laser was performed in Mainz. The laser provides narrow bandwidth (~20 MHz) pulsed laser light. Results compared with high-resolution collinear laser spectroscopy at JYFL. High resolution RIMS Collinear laser spectroscopy 244 Pu Pu Pu Pu + Publication under preparation

16 Gas jet laser spectroscopy target collector plates ionization volume SPIG measuring station dipole magnet Alpha counts in 50 s / 100 s Ac (τ 1/2 =170 ms) - in gas cell - in gas jet Figures of merit: Resolution ~ 5e-7 (FWHM= 400 MHz) Selectivity ~ 200 Efficiency ~ 0.5% Wavenumbers (cm -1 ) Developments towards gas-jet laser spectroscopy: S. Raeder et al., NIMB (2016); doi 1016/j.nimb

17 Developing well-collimated jets Task 2 (2.2 - Develop collimated gas jets with high Mach numbers) Imaging using the Planar Laser Induced Fluorescence technique Obtain information on velocity, temperature and density distributions in the gas jet Argon Gas cell Cu

18 First images using stable Cu Stagnation pressure P 0 = 320 mbar; M = 5.5; P jet = 0.8 mbar Image fluorescence of stable Cu from ICCD Jet profile of Cu vs laser detuning y x Gas jet Laser 10 mm Tailoring the gas jet: different background pressures P1 = 30 mbar P1 = 1.8 mbar

19 RESIST is underway & already meeting milestones!! RESIST kick-off meeting already held in Leuven, Sept. 24th, 2015 Next Annual workshop to be held in fall of 2016 Thanks to all my collaborators for input Material provided by: Rafael Ferrer (Leuven) Bruce Marsh (CERN) Mustapha Laaiaoui (GSI) Daniele Scarpa (INFN) Klaus Wendt (Mainz)

20 Scheme comparison: ISOL vs. IGLIS Recent results on Pu at Mainz and JYFL illustrates the effect of the environment on excitation schemes. Pu cm -1 AI/non-resonant/Rydberg-AI IP λ cm -1 J=1 λ 1 = nm J=2 λ 1 λ cm -1 λ 2 = nm 0 cm -1 J= cm -1 J=0 S. Raeder et al., Anal. Bioanal. Chem. 404 (2012) 2163 I. Pohjalainen, I.D. Moore et al., NIMB (2016) in press

21 RESIST budget summary

22 Current status of laser spectroscopy Venturing towards uncharted territory. P. Campbell, I.D. Moore, and M. Pearson, PPNP 86 (2016) 127 Unpublished Recent work mostly by resonance ionization spectroscopy (RIS) Recent work mostly by collinear laser spectroscopy