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Euroschool on Physics with Exotic Beams, Mainz 2005

LectureLecture SeriesSeries::Atomic PhysicsAtomic Physics Tools inTools in

Nuclear PhysicsNuclear PhysicsIII.III. Recent Laserspectroscopic ResultsRecent Laserspectroscopic Results

Klaus BlaumKlaus BlaumJohannes GutenbergJohannes Gutenberg--University MainzUniversity Mainz

and GSI Darmstadt, Germanyand GSI Darmstadt, Germany


OutlineOutline

1. Collinear laser spectroscopy (COLLAPS, IGISOL)

2. Atom trap laser spectroscopy (ATTA)

3. Resonance laser spectroscopy (ToPLiS)


COLLAPS SetupCOLLAPS Setup

Collinear laser spectroscopy with resonance ionization detection


The Collinear PrincipleThe Collinear Principle

“Collinear” ⇒ Superposition of laser and fast atom-/ion beam

“fast beam” (ISOLDE: Ukin(Ionen)=60 keV):

⇒Doppler shift of the usedtransition in neon about 1.2 THz

Energy spread of the ions is constant in acceleration ⇒ Compression of the velocity distribution in beam direction:

⇒ Energy spread in beam direction: δE < 50 µeV ≈ 0.5 K

Doppler shift ⇒ laser at fixed frequency and “Doppler tuning”, i.e. Scan of the velocity of the ions

220Doppler mcUe2

11

≅ββ−β±

×ν=ν ,

UemTkvconstvmvmvE

2)(

222

21 =⇒=== δδδδ


Optical Excitation SchemeOptical Excitation Scheme of Neof Ne0 1 2

J

3s’[1/2]0

2p6 1S0

3s’[1/2]1

3s[3/2]1 3s[3/2]2

3p[3/2]2

3p[3/2]1

12.2%

∆Eion Na+

λ = 614.47 nm

-2

-4

-6

-20

-22

Ne*

3s’[1/2]0

2p6 1S0

3s’[1/2]1

3s[3/2]1 3s[3/2]2

3p[3/2]2

3p[3/2]1

12.2%

∆Eion Na+

λ = 614.47 nm

-2

-4

-6

-20

-22

Ne*

Charge exchange at Na → metastable state

opt. pumping in the ground state

Collision with chlorine gas: Utilization of differentionisation energies out of the meta stablestate and ground state


HFS and ISHFS and IS MeasurementsMeasurements

Collis.ionization

Ions

Atoms

63750 63800 63850 63900 63950 640000.090

0.095

0.100

0.105

0.110

0.115

0.120

63750 63800 63850 63900 63950 640000.090

0.095

0.100

0.105

0.110

0.115

0.120

Nor

mat

edSi

gnal

7x105

8x105

9x105

1x106

1x106

Ato

m-S

igna

l

9x104

1x105

1x105

1x105

1x105

1x105

2x105

Ione

n-Si

gnal

19Ne

⇒ decisive increase in sensitivity:

Measurement on 28Ne with 45 Ions / ISOLDE pulse

⇒ 5 hours of data taking per spectrum


ChargeCharge RadiiRadii:: TheoryTheory and Experimentand Experiment

Collaps upper limitCollaps lower limitFinite range Droplet

Ne


LaserspectroscopyLaserspectroscopy at IGISOL / Jyväskyläat IGISOL / Jyväskylä

Buffer gas cell, pHe ~ 0.1 mbar

DecelerationCollisional cooling in an

RF-quadrupole Acceleration

Beam in Beam out

40 kV

Turbo pump500 l/s

Turbo pump1300 l/s

Turbo pump900 l/s

High vacuum 10-6 mbar

Intermediate vacuum 10-4 mbar Electrodes

HV isolator

IGISOL: E ~40 keV, δE ~100 eV

DC-cooler: E~ 40 keV, δ E < 1 eVtransmission > 60%

Buncher: Accumulation time 10 ms -10 s(typically 100 ms - 1 s)bunch length 15 µs (FWHM)

Bunching for collinear laser spectroscopy:

A. Nieminen et al.,Phys. Rev. Lett. 88 (2002)


Bunching for Collinear LaserspectroscopyBunching for Collinear Laserspectroscopy


Preparation TechniquePreparation Technique: Laser Ion: Laser Ion Source TrapSource Trap

Principle: RFQ Trap and Laser System

efficient and highly-selective (R > 105) production of exotic ionspreparation of cleaned, cooled, and bunched beams with low emittanceproduction of polarized radioactive ion beams by optical pumpingfirst demonstration of cooled and pulsed beam release in Mainz (2004)

Goals and Results

Ti:Sa 1

Ti:Sa 2

Ti:Sa 3

Nd:YAG

Ion Beam

Gas filledRFQ Trap

Ion Repeller

to on-lineExperiments

Laser-beams

Ion Source HV Platform

Atom source

60 KV Mass separator Laser System

K. Wendt et al., Nucl. Phys. A 746, 47c (2004)


Status in 2003: ChargeStatus in 2003: Charge RadiiRadii of He and Liof He and Li--IsotopesIsotopes

3He∞

1/2+

4He∞0+

6He807 ms

0+

8He119 ms

0+

3He∞

1/2+

4He∞0+

6He807 ms

0+

8He119 ms

0+

Shiner et al.PRL 18, 3553 (1995),Laser spectroscopy in an atomic beam

G. Carboni et al.Nucl. Phys. A, 278,381 (1977)Laser Spectroscopy of muonic helium

6Li∞1+

7Li∞

3/2-

8Li838 ms

2+

9Li178 ms

3/2-

11Li8.5 ms

3/2-

6Li∞1+

7Li∞

3/2-

8Li838 ms

2+

9Li178 ms

3/2-

11Li8.5 ms

3/2-

Riis et al.PRA 49, 207 (1994)Laser spectroscopy of helium-like lithium

2rδ


Courtesy of Peter Müller,Argonne Nat. Lab

66He He –– Single AtomSingle Atom SpectroscopySpectroscopy

Photoncounter

Zeemans lower

MOT

Transversecooling

389 nm 1083 nm

Atom Trapping of 6He

6Hetrapping rate

~ 2 / min

Photoncounter

Zeemans lower

MOT

Transversecooling

389 nm 1083 nm

Atom Trapping of 6He

6Hetrapping rate

~ 2 / min

0 5 10 15 200.0

0.2

0.4

0.6

0.8

1.0

1.2

Pho

ton

coun

trate

/ kH

z

Time (s)-8 -6 -4 -2 0 2 4 6 8

50

100

150

200

250

300

Frequency (MHz)

Pho

ton

coun

ts

Single atom signal

One 6He atom

6He spectroscopy

~150 6Hein 1 hr

0 5 10 15 200.0

0.2

0.4

0.6

0.8

1.0

1.2

Pho

ton

coun

trate

/ kH

z

Time (s)-8 -6 -4 -2 0 2 4 6 8

50

100

150

200

250

300

Frequency (MHz)

Pho

ton

coun

ts

Single atom signal

One 6He atom

6He spectroscopy

~150 6Hein 1 hr

RF -Discharge

Krcarrier

gas

He*

Spectroscopy389 nm

2 3S1

1 1S0

2 3P2

3 3P2

Trap1083 nm

He level scheme

RF -Discharge

Krcarrier

gas

He*

RF -Discharge

Krcarrier

gas

He*

Spectroscopy389 nm

2 3S1

1 1S0

2 3P2

3 3P2

Trap1083 nm

He level scheme

Spectroscopy389 nm

2 3S1

1 1S0

2 3P2

3 3P2

Trap1083 nm

He level scheme

6He

7Li3+

60 MeV

6He Production @ ATLAS

Graphite

~ 1×106 / s

6He

7Li3+

60 MeV


Graphite

~ 1×106 / s

6He

7Li3+

60 MeV


Graphite

~ 1×106 / s

6He

7Li3+

60 MeV


Graphite

~ 1×106 / s

L.-B. Wang et al., PRL 93, 142501 (2004)


66He He –– NuclearNuclear Charge RadiusCharge Radius

Isotope shift(23S1 - 33P2, 6He – 4He)

43 194.772(56) MHz

6He rms charge radius

2.054(14) fm (0.7%)

L.-B. Wang et al.,PRL 93, 142501 (2004)

1.7 1.8 1.9 2.0 2.1 Point-Proton Radius of He-6 (fm)

He-6

Reaction collision

Elastic collision

Atomic isotope shift

Cluster models

No-core shell model

Quantum MC

Modelindependent!

Exp

erim

ent

Theo

ry

Tanihata ‘92

Alkhazov ‘97

This work

Csoto ‘93

Funada ‘94

Varga ‘94

Wurzer ‘97

Esbensen ‘97

Navratil ‘01

Pieper ‘04


Resonance IonizationResonance Ionization of LithiumCourtesy W. Nörtershäuser GSI Darmstadt of Lithium

2s 2S1/2

3s 2S1/2

2p 2P1/2,3/2

3d 2D3/2,5/2τ = 30 ns

2 × 735 nm

610 nm

5.3917 eV2s – 3s transition→ Narrow line2-photon spectroscopy→ Doppler cancellation

“Doubly-Resonant-4-Photon Ionization”

Spontaneous decay→ Decoupling of precise

spectroscopy and efficient ionization

2p – 3d transition → Resonance enhancement

for efficient ionization


SetupSetup forfor LithiumLithium MeasurementsMeasurements ((ToPLiSToPLiS))

Ti:Sa Laser735 nm

Dye Laser 610 nm

ElectrostaticLenses

PZT

CO -Laser2

Comparison

Serv

o

RF Generator

Reference Diode Laser I2

Servo

Reaction Products

Surface Ion Source

Magnet

Servo

Servo

W Target

Ion Signal

6,7,8,9,11Li

Ti:Sa Laser735 nm

Dye Laser 610 nm

ElectrostaticLenses

PZT

CO -Laser2

Comparison

Serv

o

RF Generator

Reference Diode Laser I2

Servo

Reaction Products

Surface Ion Source

Magnet

Servo

Servo

W Target

Ion Signal

6,7,8,9,11Li

• 8,9,11Li all have half-life < 1 s: must be studied at accelerator online mass separator facilities

• Use thin (~300 nm) heated carbon foils to catch ions, neutralize, and rapidly release neutral atoms

• Use resonant enhancement cavity to efficiently drive two-photon transitions

• Use beat-frequency methods for reliable and precise control of resonant laser


77Li LineLi Line ShapeShape

5000 5500 6000 6500 7000100

101

102

103

104

Cou

nts

DL/TiSa - Beat Frequency (MHz)

F=1

→F=

1

F=2

→F=

2 7LiLinewidth Voigt

ΓL= 4.6 (1) MHz (FWHM)ΓG= 1.8 (1) MHz (FW 1/e)

Expected Natural WidthΓL= 2.7 MHz (FWHM)

Background Gaussian ΓG ≈ 1.2 GHzrelative Amplitude ≈ 3 × 10-3

Amplitude RatioF=1 : F=2 2.85 : 5

F =2F = 1

F= 2

F= 12S1/2

3S1/2


1111LiLi ResonanceResonance

6360 6370 6380 6710 6720 67300

50

100

150

200

Cou

nts

/ 50

s

Beat Frequency (MHz)

F= 2F= 1

F= 2

F= 12S1/2

3S1/2

F =

1 →

F =

1

F =

2 →

F =

2 11LiProduction Rate:30,000 /sLifetime:8.5 ms !

F= 2F= 1

F= 2

F= 12S1/2

3S1/2

F =

1 →

F =

1

F =

2 →

F =

2 11LiProduction Rate:30,000 /sLifetime:8.5 ms !

21 85

83 ννν11

cg +=


ChargeCharge RadiiRadii of Lithiumof Lithium IsotopesIsotopes

6 7 8 9 10 11

2.1

2.2

2.3

2.4

2.5

2.6

2.7 This Tan85 LBSM SVMC DCM AV18IL2 NCSM FMD

r c (fm

)

Li Isotope

EXPERIMENTInteraction Cross Section(Tanihata, 1985)

TOPLIS, Isotope Shift(GSI + TRIUMF 2004)

THEORYGFMC–AV18IL2(Pieper, Wiringa 2001/02)

SVMC (Suzuki 2002)

LBSM (Navratil 1998/2003)

DCM (Tomaselli 2002)

FMD (Neff, priv. comm.)++


LaserLaser SpectroscopySpectroscopy inin thethe Chart ofChart of NuclidesNuclides

2 8

20

28

20

20-31Na

36-47K

39-50Ca

2

8

32-40,46Ar

17-28Ne

5044,45Ti

28

11Be6-11Li

Exclusive approach for a model-independent <r2> determination of short-lived nuclei !

170-178Hf161-179Lu

200-210Po

101-110Ag

82

126

152

82

72-96Kr

76-98Rb

77-100Sr

102-120Cd

104-127In

108-132Sn

116-146Xe

118-146Cs

132-150Nd

138-154Sm

138-159Eu

146-165Dy

151-165Ho

150-167Er153-172Tm

153-176Yb

178-198Pt

183-197Au181-206Hg

185-214Pb

202-213Bi

207-228Fr208-232Ra

187-208Tl

202-225Rn

182-193Ir

240-244Am

227Ac232Th

235-238U

237Np

238-244Pu

249Cf249Bk

254Es

248Cm

50

147-159Tb

120-148Ba

255Fm

146-160Gd

87-102Zr


LaSpecLaSpec at NUSTAR / FAIRat NUSTAR / FAIR


SummarySummary ofof LectureLecture IIIIII

•• Laser Spectroscopy of fewLaser Spectroscopy of few--electron systems combined with precise electron systems combined with precise atomic physics calculations can provide accurate atomic physics calculations can provide accurate rmsrms charge radii.charge radii.

•• This method was previously used for charge radii determination oThis method was previously used for charge radii determination of f stable isotopes (H, He, Hestable isotopes (H, He, He--like Lithium).like Lithium).

•• First measurements on light shortFirst measurements on light short--lived nuclei were performed.lived nuclei were performed.

•• ModelModel--independent charge radii of halo nuclei (independent charge radii of halo nuclei (66He, He, 1111Li) were Li) were obtained for the first time.obtained for the first time.

• Discrimination of nuclear models • Better understanding of nuclear structure and

nucleon–nucleon interactions

Thanks a lot foryour attention.

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