Laser Spectroscopy with the Leuven gas cellbased Laser
Laser Spectroscopy with the Leuven gas cell-based Laser Ion Source @ LISOL Rafael Ferrer Workshop and Users meeting 2011 5 -7 December 2011, CERN OUTLINE • Production of exotic beams with RILIS @ LISOL • In-Gas Cell Laser Spectroscopy • Progress toward a full implementation of In-Jet Laser Spectroscopy
Resonance Ionization Laser Ion Source: RILIS • SELECTIVE (element and isomer) & EFFICIENT PRODUCTION OF RARE ISOTOPE BEAMS U. Koester et al. , Nucl. Phys. A 701 (2002) 441 c • IN-SOURCE ATOMIC SPECTROSCOPY G. D. Alkhazov et al. , NIM B 69 (1992) 517 Ø Hot Cavity Ø Gas Cell - No refractory elements - T 1/2 element dependent - Sensitivity 1 ion/s (182 Pb) - Resol~ 4 GHz (59 Cu) (Doppler) - Produced Ion beams ~30 elements - All elements available - T 1/2 cell evacuation time - Sensitivity < 1 ion/s (97 Ag) - Resol. ~ 3 GHz (59 Cu) (Pressure) - Produced Ion beams ~15 elements V. N. Fedoseev et al. , NIM B 266 (2008) 4378 Yu. Kudryavtsev et al. , NIM B 267 (2009) 2908 R. Ferrer - ISOLDE WORKSHOP ’ 11 -
LISOL Beams since 1994 Heavy Ion-induced fusion evaporation reactions: Rh, Ru, Ti, Sn, In, Ag, Ac EPJ A 21 (2004)243 Light Ion-induced fusion evaporation reactions: Co, Ni, Mn, Cr, V, Cu Stopping of 185 Me. V stable Ni beam Characterization of gas cell PRC 59 (1999) 2416 PRL 103 (2009) 102501 PRC 81 (2010) 014314 NIM B 187 (2002) 535; NIM B 226 (2004) 401 Sp. fission of 252 Cf: Rh, Ru, Mo, Pd NIM B 266 (2008) 4368 Proton-induced fission of 238 U: Fe, Co, Ni, Cu PRL 81 (1998) 03100, PRC 64 (2001) 054308 PRC 74 (2006) 054309, PRC 78 (2008) 041307(R) PRC 79 (2009) 044309, PRC 79 (2009) 044325 R. Ferrer - ISOLDE WORKSHOP ’ 11 - • Implementation of ‘Dual Chamber’ gas cell improves ionization efficiency and selectivity In-source laser spectroscopy at LISOL Yu. Kudryavtev et al. , NIM B 267 (2009) 2908
Dual Chamber Gas Cell Ar/He from gas purifier Laser beams Longitudinal 500 mbar • Laser ionization efficiency for high cyclotron beam current Stopping chamber Ø 4 cm Beam from Cyclotron Laser Ionization chamber Ø 1 cm Ion collector Laser beams Transverse Exit hole Ø 0. 5 – 1 mm Separation of stopping and laser ionization volumes improves: • Ion selectivity Production of 94 Rh Selectivity: Ionization chamber [Laser(on)/Laser(off)] Ion Collector OFF = 450 Filament Ion Collector ON = 2200 In-gas-cell spectroscopy of neutron deficient Cu isotopes T. E. Cocolios et al. , PRL 103, 102501 (2009) T. E. Cocolios et al. , PRC 81, 014314 (2010) SPIG Similar measurements near N=Z line around A=100 R. Ferrer - ISOLDE WORKSHOP ’ 11 -
In-Gas-Cell Laser Spectroscopy of Ag 92 Mo(14 N – 130 Me. V, 2 pxn)104−x. Ag N=50 64, nat. Zn(36 Ar – 125 Me. V, pxn)101− 97 Ag 99 Ag 101 Ag Derived experimental proton g-factors Open circle calculated value assuming I=7/2+ U. Dinger et al. , Nucl. Phys. A 503 (1989) 331 D. Vandeplassche et al. , Hyperfine Interact. 22 (1985) 483 Iain Darby Phys. Lett. B ( in preparation) R. Ferrer - ISOLDE WORKSHOP ’ 11 -
Attempt at Laser Spectroscopy of Sn continuum Aut. state 92 Mo(16 O-100 Me. V, 2 -3 n)105, 106 Sn 1 P 1 λ 2=454. 9 nm 39257. 1 cm-1 • Strong l-dependence of Sn on pressure • No possibility for HFS measurements (FWHM~20 GHz) 3 P argon 120 Sn l 1 IP 59232. 69 cm-1 λ 1=254. 7 nm 0 argon 120 Sn l 2 Shift = -4. 0(0. 3) MHz/mbar Broadening=32(4) MHz/mbar R. Ferrer - ISOLDE WORKSHOP ’ 11 - Shift = -150(10) MHz/mbar Broadening=210(25) MHz/mbar
Broadband Spectroscopy on Ac 46660. 6 cm-1 197 Au(20 Ne-145 Me. V, 4 -5 n)212, 213 Ac continuum Cross section 2. 3 mb for 212, 213 Ac I. P. 43398 cm-1 439. 21 nm 23898. 86 cm -1 1 ST Step 4 P 5/2 2 D Ac 3/2 212 Ac Counts on SEM (arb. u. ) Ref. Cell @LARISSA 418. 312 nm g. s. 2 nd Step 227 Ac FWHM= 24 GHz Alpha counts in 300 s FULL POWER FWHM= 86 GHz http: //www. gsi. de/forschung/ap/projects/laser/survey. html R. Ferrer - ISOLDE WORKSHOP ’ 11 - Gas Cell @LISOL 212 Ac Ref. Cell @LARISSA FWHM= 81 GHz FULL POWER FWHM= 170 GHz 227 Ac Gas Cell @LISOL 212 Ac POWER ATTEN. FWHM= 32 GHz Wavenumbers - 23898. 93 (cm -1) Wavenumbers – 46660. 65 (cm -1)
In-Jet Laser Spectroscopy • Increase Resolution and Sensitivity - Ionization in cold jet expanding out of the gas cell Ionization in LIST mode K. Blaum et al. , NIM B 204 (2003) 331 Demonstrated proof of principle @ LISOL T. Sonoda et al. NIM B 267 (2009) 2918 Ref. Cell nat. Ni FWHM= ~ 2 GHz 58 Ni Gas cell Ar 500 mbar FWHM=6. 5 GHz SPIG - Low density and low temperature in jet reduce significantly Doppler and pressure broadening • Requirements to obtain full benefits: FWHM= ~ 2 GHz 43089. 2 - Improve time and spatial overlap of laser beams with atoms R. Ferrer - ISOLDE WORKSHOP ’ 11 - 58 Ni 43089. 6 Wavenumber [cm-1] 43090. 0
Improving Time Overlap • Test of a high pulse repetition rate laser system (Uni-Mainz & GANIL) - Performance comparison between high repetition Ti: sa lasers and LISOL dye lasers - Comparable results for in-gas-cell ionization - A factor of 60 reduction between in-gas cell and in-jet ionization for Ti: sa lasers (700 reduction for dye lasers) - HFS of stable 63 Cu in the SPIG limited by laser bandwidth R. F. , V. Sonnenschein et al, NIM B in preparation R. Ferrer - ISOLDE WORKSHOP ’ 11 -
Improving Spatial Overlap • Implementation of de Laval nozzle and bent RFQ - SIMION simulations of new segmented RFQ ion guide : Transmission vs. p, RF amp, DC gradient Extraction RFQ 90 o-bent RFQ pumping barrier RFQ Prototype Acceleration region Gas Cell - Test de Laval nozzle and new RFQ @LISOL • Awarded ERC Advanced Grant: new lab in K. U. Leuven for Heavy Element Laser Ionization Spectroscopy (HELIOS) M. Reponen et al. , NIM A 635 (2011) 24 R. Ferrer - ISOLDE WORKSHOP ’ 11 - • Final measurements @ S 3 (SPIRAL 2): Leuven gas cell will couple fragment separator with HRS
Single Mode Selection in Dye Laser by a Thick Etalon • Study of typical LISOL narrow-band pulse using FP interferometer - Radial profile of interference ring shows four oscillation modes - Separation between modes is 400 MHz mode FWHM= 150 MHz Laser bandwidth ~1. 4 GHz (SHG) • Implementation of a thicker etalon (14 mm air spaced) allows selection of a single mode Elimination of mode competition R. Ferrer - ISOLDE WORKSHOP ’ 11 -
Spectrum of the low energy HFS components of the 244 nm line in 63, 65 Cu A B Ref. Cell 63 Cu 65 Cu 450 MHz • Bandwidth of 450 MHz without minimizing power nor Doppler broadening R. Ferrer - ISOLDE WORKSHOP ’ 11 -
Amplification of CW Single Mode Diode Laser in Pulsed Dye Amplifier Tunable cw Diode Laser (Toptica) 654. 98 nm Dye Amplifier Amp. II Amp. I SHG 327. 49 nm KDP Pulse Energy (u. J) Excimer Xe. Cl Laser 400 300 200 100 0 0 100 Power Diode Laser (m. W) R. Ferrer - ISOLDE WORKSHOP ’ 11 - 200 Towards Ref. Cell
Spectrum of the high energy HFS components of the 327 nm line in 63, 65 Cu C D+C D • New ionization scheme required to meet tuneability of diode laser Ref. Cell 63, 65 Cu 150 MHz 63 Cu 65 Cu • Estimated 90 MHz Fourier-limited (5 ns) laser bandwidth is affected by residual Doppler broadening resulting in a signal linewidth of 150 MHz R. Ferrer - ISOLDE WORKSHOP ’ 11 -
Acknowledgments LISOL team: R. F, L. Ghys, M. Huyse, Yu. Kudryavtsev, D. Pauwels, D. Radulov, L. Rens, P. Van den Bergh, C. Van Beveren, and P. Van Duppen LISOL Alumni: T. Cocolios, I. G. Darby, T. Sonoda Collaborators: University of Mainz A. Hakimi, T. Kron, S. Raeder, S. Richter, J. Rossnagel, K. Wendt GANIL-SPIRAL 2 B. Bastin, S. Franchoo, N. Lecesne, B. Osmond, H. Savajols , J. C. Thomas JYFL University of Jyväskylä I. Moore, M. Reponen, V. Sonnenschein JINR-Dubna S. Zemlyanoy R. Ferrer - ISOLDE WORKSHOP ’ 11 -
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