M.D. Seliverstov February 2013 CERN 1st LA³NET Topical Workshop on Laser Based Particle Sources

Contents: Resonant photoionization in-source spectroscopy: advantages and limitations General problems of data analysis (isotopes with I = 0) Correction to the laser power Laser lineshape asymmetry Isotopes with I > 0: hyperfine splitting Relative intensities of hfs lines Saturation hfs levels population redistribution Conclusions and outlook 1st LA³NET Topical Workshop on Laser Based Particle Sources, February 2013, CERN

Resonant photoionization in-source spectroscopy 3 Isotope shift  A,A’  A,A ’ = F A,A ’ + MS Rms charge radius  A,A’ =   r 2  A,A ’ + C 2   r 4  A,A ’ + … = 0.93   r 2  A,A ’ Relative line position  hyperfine constants A & B  m I, Q S For 208 Pb at T LIS = 2000K:  D = 2.4 GHz (FWHM)  A,A+1 = 1 GHz For Pb isotope chain: Doppler limitation: 1st LA³NET Topical Workshop on Laser Based Particle Sources, February 2013, CERN Laser linewidth about 1 GHz

4 Spectra of even-A isotopes of Pb and Po 1st LA³NET Topical Workshop on Laser Based Particle Sources, February 2013, CERN Resonant photoionization in-source spectroscopy

Fitting function 5 1st LA³NET Topical Workshop on Laser Based Particle Sources, February 2013, CERN The simplest case: General form: (Voigt profile) Saturation is possible Laser lineshape can be an asymmetrical function

Asymmetry of the fitting function 6 1st LA³NET Topical Workshop on Laser Based Particle Sources, February 2013, CERN “standard” Lorentzian: “deformed” Lorentzian:

Additional correction to asymmetry of the lineshape 7 1st LA³NET Topical Workshop on Laser Based Particle Sources, February 2013, CERN

Correction to the laser power 8 Working area 1st LA³NET Topical Workshop on Laser Based Particle Sources, February 2013, CERN Optical transition saturation

Saturation broadening 9 1st LA³NET Topical Workshop on Laser Based Particle Sources, February 2013, CERN

Saturation + desynchronization of the laser pulses 10 1st LA³NET Topical Workshop on Laser Based Particle Sources, February 2013, CERN Dye lasers with CVL pumping Dye lasers with Nd:YAG pumping: No timing problems Ti:Sa – timing problems again

Corrections for desynchronization 1st LA³NET Topical Workshop on Laser Based Particle Sources, February 2013, CERN

Corrections for desynchronization 1st LA³NET Topical Workshop on Laser Based Particle Sources, February 2013, CERN

Hyperfine splitting (hfs) 13 Photoionization scheme for Pb 1st LA³NET Topical Workshop on Laser Based Particle Sources, February 2013, CERN

Hyperfine splitting (hfs) 1st LA³NET Topical Workshop on Laser Based Particle Sources, February 2013, CERN

Hyperfine splitting (hfs) 1st LA³NET Topical Workshop on Laser Based Particle Sources, February 2013, CERN Photoionization scheme for Po

Hyperfine splitting (hfs) Position of the hfs lines: Relative intensities (simplified form): 1st LA³NET Topical Workshop on Laser Based Particle Sources, February 2013, CERN

Hyperfine splitting (hfs) 1st LA³NET Topical Workshop on Laser Based Particle Sources, February 2013, CERN

Rate equations To take into account the saturation of transitions, pumping processes between hyperfine structure (hfs) components and a population redistribution of the hfs levels the number of photoions N ion for each frequency step was calculated by solving the rate equations for the given photoionization scheme: At t = 0: 1st LA³NET Topical Workshop on Laser Based Particle Sources, February 2013, CERN

Rate equations ionization N ion F1F1 F2F2 F0F0 F’1F’1 F’2F’2 F’0F’0 F’’ 1 F’’ 2 F’’ 0 NFNF N’F’N’F’ N’’ F’’ W F’F’’ W F’’ F’ W ion W FF’ W F’F 1st LA³NET Topical Workshop on Laser Based Particle Sources, February 2013, CERN

King plot for Po isotopes King plot for Po atomic transitions 843 nm (our data) and 255 nm. 200–210 Po 1st LA³NET Topical Workshop on Laser Based Particle Sources, February 2013, CERN

Charge radii of Po isotopes 1st LA³NET Topical Workshop on Laser Based Particle Sources, February 2013, CERN

Rate equations for the polarized light M F’ -3/2 -1/2 1/2 3/2 F = 1/2  F’ = 3/2 M F -1/2 1/2 1st LA³NET Topical Workshop on Laser Based Particle Sources, February 2013, CERN Q = M F – M’ F

Rate equations for the polarized light M F’ -3/2 -1/2 1/2 3/2 F = 1/2  F’ = 3/2 M F -1/2 1/2 1st LA³NET Topical Workshop on Laser Based Particle Sources, February 2013, CERN Q = M F – M’ F Linear polarization

Universal fitting program 1st LA³NET Topical Workshop on Laser Based Particle Sources, February 2013, CERN

Conclusions The laser ion source is not only a very effective in its normal use as an element- selective tool for producing intense ion beams, but it can be used as a very powerful atomic-spectroscopy tool due to the resonance character of the photoionization (In-Source Laser Resonant Photoionization Spectroscopy). In contrast to other laser spectroscopic techniques, in that case the laser frequency scanning procedure is applied directly within the mass-separator ion source. The main advantage of this technique is its very high sensitivity, nevertheless its spectral resolution is Doppler-limited, therefore the accurate data analysis is of great importance.

Thanks for your attention! 1st LA³NET Topical Workshop on Laser Based Particle Sources, February 2013, CERN