Laser Spectroscopy with the Leuvengas cell-based Laser Ion Source @ LISOL

Workshop and Users meeting 2011 5-7 December 2011, CERN

Rafael Ferrer

OUTLINE

• Production of exotic beams with RILIS @ LISOL

• In-Gas Cell Laser Spectroscopy

• Progress toward a full implementation of In-Jet Laser Spectroscopy

• SELECTIVE (element and isomer) & EFFICIENT PRODUCTION OF RARE ISOTOPE BEAMS

Hot Cavity

- No refractory elements- T1/2 element dependent- Sensitivity 1 ion/s (182Pb) - Resol~ 4 GHz (59Cu) (Doppler) - Produced Ion beams ~30 elements

Gas Cell

- All elements available - T1/2 cell evacuation time- Sensitivity < 1 ion/s (97Ag) - Resol. ~ 3 GHz (59Cu) (Pressure)- Produced Ion beams ~15 elements

V.N. Fedoseev et al., NIM B266 (2008) 4378 Yu. Kudryavtsev et al., NIM B267 (2009) 2908

• IN-SOURCE ATOMIC SPECTROSCOPY

Resonance Ionization Laser Ion Source: RILIS

R. Ferrer - ISOLDE WORKSHOP ’11 -

G. D. Alkhazov et al., NIM B69 (1992) 517

U. Koester et al., Nucl. Phys. A 701 (2002) 441c

R. Ferrer - ISOLDE WORKSHOP ’11 -

PRL 81 (1998) 03100, PRC 64 (2001) 054308PRC 74 (2006) 054309, PRC 78 (2008) 041307(R)PRC 79 (2009) 044309, PRC 79 (2009) 044325

Proton-induced fission of 238U: Fe,Co,Ni,Cu

Light Ion-induced fusion evaporation reactions: Co,Ni,Mn,Cr,V,Cu

PRC 59 (1999) 2416PRL 103 (2009) 102501PRC 81 (2010) 014314

Stopping of 185 MeV stable Ni beam Characterization of gas cell

NIM B 187 (2002) 535; NIM B 226 (2004) 401

Sp. fission of 252Cf: Rh,Ru,Mo,PdNIM B 266 (2008) 4368

Heavy Ion-induced fusion evaporation reactions: Rh,Ru,Ti,Sn,In,Ag,Ac

EPJ A 21 (2004)243

In-source laser spectroscopy at LISOL

Yu. Kudryavtev et al., NIM B 267 (2009) 2908

• Implementation of ‘Dual Chamber’ gas cell improves ionization efficiency and selectivity

LISOL Beams since 1994

Dual Chamber Gas Cell

Separation of stopping and laser ionization volumes improves:

• Laser ionization efficiency for high cyclotron beam current

• Ion selectivity

LaserIonization chamber

Laser beamsLongitudinal

Laser beamsTransverse

SPIG

Ar/He from gas purifier

Ion Collector

Ionizationchamber

Stopping chamberØ 4 cm

Filament

Beam from Cyclotron

Ion collector

500 mbar

Exit hole Ø 0.5 – 1 mm

Ø 1 cm

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)

Similar measurements near N=Z line around A=100

Selectivity:

[Laser(on)/Laser(off)]

Ion Collector OFF = 450

Ion Collector ON = 2200

Production of 94Rh

R. Ferrer - ISOLDE WORKSHOP ’11 -

101Ag99Ag97Ag

R. Ferrer - ISOLDE WORKSHOP ’11 -

In-Gas-Cell Laser Spectroscopy of Ag

Iain Darby Phys. Lett. B (in preparation)

N=50

U. Dinger et al., Nucl. Phys. A 503 (1989) 331 D. Vandeplassche et al., Hyperfine Interact. 22 (1985) 483

92Mo(14N – 130 MeV,2pxn)104−xAg

64,natZn(36Ar – 125 MeV,pxn)101−97Ag

Derived experimental proton g-factors Open circle calculated value assuming I=7/2+

R. Ferrer - ISOLDE WORKSHOP ’11 -

21978 21979 21980 21981 21982 21983 21984

0.0

0.2

0.4

0.6

0.8

1.0

Wavenumber (cm-1)

500 mbar 390 mbar 300 mbar 200 mbar 150 mbar 100 mbar RC

Cur

rent

on

SE

M (nA

)

19627.6 19627.8 19628.0 19628.2 19628.4 19628.6 19628.8 19629.0

0.0

0.2

0.4

0.6

0.8

1.0

Wavelength (cm-1)

100 mbar 140 mbar 190 mbar 280 mbar 400 mbar 510 mbar RC

Curr

ent on S

EM

(nA

)

Attempt at Laser Spectroscopy of Sn

Shift = -150(10) MHz/mbarBroadening=210(25) MHz/mbar

Shift = -4.0(0.3) MHz/mbarBroadening=32(4) MHz/mbar

• Strong l-dependence of Sn on pressure

• No possibility for HFS measurements (FWHM~20GHz)

l1 l2

1P1

3P0

continuum

λ1=254.7 nm

λ2=454.9 nm

IP 59232.69 cm-1

39257.1 cm-1

Aut. state92Mo(16O-100 MeV,2-3n)105,106Sn

120Sn 120Sn

argon argon

0

50

100

150

200

250

R. Ferrer - ISOLDE WORKSHOP ’11 -

Broadband Spectroscopy on Ac

197Au(20Ne-145 MeV,4-5n)212,213Ac Cross section 2.3 mb for 212,213AcI.P. 43398 cm-1

2D3/2

4P5/2

418.312 nm

439.21 nm

Acg.s.

continuum

23898.86 cm-1

46660.6 cm-1

0

25

50

75

100

125

150

FWHM= 24 GHzCo

unts

on

SEM

(ar

b. u

.)FWHM= 81 GHz

1ST Step 2nd StepRef. Cell @LARISSA Ref. Cell @LARISSA

227Ac 227Ac

212Ac

http://www.gsi.de/forschung/ap/projects/laser/survey.html

-8 -6 -4 -2 0 2 4 6 80

50

100

150

200

Wavenumbers - 23898.93 (cm-1)

Alph

a co

unts

in 3

00 s

FULL POWERFWHM= 86 GHz

POWER ATTEN. FWHM= 32 GHz

Wavenumbers – 46660.65 (cm-1)

FULL POWER FWHM= 170 GHz

Gas Cell @LISOL Gas Cell @LISOL

212Ac 212Ac

-4 -3 -2 -1 0 1 2 3 4 5 60

50

100

150

200

R. Ferrer - ISOLDE WORKSHOP ’11 -

In-Jet Laser Spectroscopy• Increase Resolution and Sensitivity

- Ionization in cold jet expanding out of the gas cell

T. Sonoda et al. NIM B267 (2009) 2918

natNi

FWHM= ~ 2 GHz

FWHM= ~ 2 GHz

SPIG 58Ni

Ar 500 mbar

Gas cell 58NiFWHM=6.5 GHz

Ref. Cell

43089.2 43089.6 43090.0Wavenumber [cm-1]

• Requirements to obtain full benefits:

K. Blaum et al., NIM B204 (2003) 331

Ionization in LIST mode

- Low density and low temperature in jet reduce significantly Doppler and pressure broadening

- Improve time and spatial overlap of laser beams with atoms

Demonstrated proof of principle @ LISOL

0

25

50

75

100

0

25

50

75

-0.02 -0.01 0.00 0.01 0.02

0

25

50

75

- 1227.45887 (THz)

Ion

Sig

nal (

arb.

u.)

Ref. Cell

Gas Cell Ar 200 mbar

SPIG

100 1000 10000

10

100

Ti:sa lasers Dye lasers

- co

unts

in 1

00 s

Rep. Rate (Hz)

59Cu+

Improving Time Overlap

R. Ferrer - ISOLDE WORKSHOP ’11 -

- 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 63Cu in the SPIG limited by laser bandwidth

R. F., V. Sonnenschein et al, NIM B in preparation

• Test of a high pulse repetition rate laser system (Uni-Mainz & GANIL)

Improving Spatial Overlap

R. Ferrer - ISOLDE WORKSHOP ’11 -

90o-bent RFQ

pumping barrier

Extraction RFQ

Acceleration region

Gas Cell

• Implementation of de Laval nozzle and bent RFQ - SIMION simulations of new segmented RFQ ion guide : Transmission vs. p, RF amp, DC gradient

M. Reponen et al., NIM A 635 (2011) 24

- Test de Laval nozzle and new RFQ @LISOL

RFQ Prototype

• Final measurements @ S3 (SPIRAL2): Leuven gas cell will couple fragment separator with HRS

• Awarded ERC Advanced Grant: new lab in K.U. Leuven for Heavy Element Laser Ionization Spectroscopy (HELIOS)

R. Ferrer - ISOLDE WORKSHOP ’11 -

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= 150MHz 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 -

40943.4 40943.5 40943.6 40943.7 40943.80.0

0.5

1.0

1.5

2.0

2.5

Cou

nts

on S

EM

(ar

b. u

.)

Wavenumbers (cm-1)

450 MHz65Cu

63Cu

A B Ref. Cell

Spectrum of the low energy HFS components of the 244 nm line in 63,65Cu

• 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

0 20 40 60 80 100 120 140 160 1800

100

200

300

400

Power Diode Laser (mW)

Puls

e E

nerg

y (u

J)

ExcimerXeCl Laser

Dye AmplifierTunable cw DiodeLaser (Toptica) SHG

KDP

Amp. I Amp. IITowardsRef. Cell

327.49 nm654.98 nm

R. Ferrer - ISOLDE WORKSHOP ’11 -

Spectrum of the high energy HFS components of the 327 nm line in 63,65Cu

0.46 0.48 0.50 0.52 0.54 0.56 0.58 0.60

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

Sig

nal o

n S

EM

(ar

b. u

)

Wavenumber - 30535 (cm-1)

• New ionization scheme required to meet tuneability of diode laser

65Cu63Cu

63,65Cu

C DD+C

150 MHz

• Estimated 90 MHz Fourier-limited (5ns) laser bandwidth is affected by residual Doppler broadening resulting in a signal linewidth of 150 MHz

Ref. Cell

AcknowledgmentsLISOL 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 MainzA. Hakimi, T. Kron, S. Raeder, S. Richter, J. Rossnagel, K. Wendt

JYFL University of Jyväskylä I. Moore, M. Reponen, V. Sonnenschein

GANIL-SPIRAL2B. Bastin, S. Franchoo, N. Lecesne, B. Osmond, H. Savajols , J. C. Thomas

JINR-Dubna S. Zemlyanoy

R. Ferrer - ISOLDE WORKSHOP ’11 -