Radium AtomRadium AtomElectron and Nuclear EDM’sElectron and Nuclear EDM’s

Lorenz Willmann, University of Groningen, KVIPandT2008, Heidelberg, 9­11 June 2008

TRIµ P:Trapped Radioactive Isotopes:

µ icro­laboratories for Fundamental Physics

OutlineOutline• TRITRIµµ PP Facility at KVI Facility at KVI• EDM’s and the Standard ModelEDM’s and the Standard Model• What about Radium?What about Radium?• Laser Cooling and TrappingLaser Cooling and Trapping

• Heavy Alkaline Earth Elements: Barium (and Radium)Heavy Alkaline Earth Elements: Barium (and Radium)• Trapped BariumTrapped Barium• Isotope shifts in BariumIsotope shifts in Barium

• SummarySummary

IonCatcher

RFQCooler

MOT

Beyond the Standard

ModelTeV

Physics

Nuc

lear

Phy

sics

Ato

mic

Phy

sics

Part

icle

Phy

sics

ProductionTarget

MagneticSeparator

MeV

meV

keV

eV

neV

AGORcyclotron

AGOR cyclotronthermal ioniser

Low energy beam line

RFQ cooler/buncher MOT

MOT

D

D

DD

Q

QQ

Q Q

QQ

Q

Magnetic separator

Production target

Trapped Radioactive Isotopes: µ icro­laboratories for Fundamental Physics

Wedge

TRITRIµµ P project and facilityP project and facility

TRITRIµµ P P Facility: LasersFacility: Lasers• Several experimentSeveral experiment

– Flexibility: diode lasers, dye laser, Ti:Sapph, and others Flexibility: diode lasers, dye laser, Ti:Sapph, and others – 21 different wavelength up and running21 different wavelength up and running– Equipment for stabilization and frequency determinationEquipment for stabilization and frequency determination– Typically more than one laser (7 for Barium atom trapping)Typically more than one laser (7 for Barium atom trapping)

Trapped Radioactive Isotopes µ icro­laboratories for Fundamental Physics

400 600 800 1000 1200 1400

10 0

10 2

Wavelength [nm]

Pow

er [m

W] dye laser Ti:Sapph

The Standard ModelThe Standard ModelThe Standard Model

3 Fundamental Forces: ­ Electromagnetic­ Electromagnetic ­ Weak­ Weak ­ Strong­ Strong

12 Fundamental Fermions: Leptons, QuarksLeptons, Quarks

12 Gauge Bosons: γγ, W+, W­, Z, W+, W­, Z00, 8 Gluons, 8 Gluons

→ → validated by many experimentsvalidated by many experiments

Large variety of models extending SM Large variety of models extending SM

Experimental verification required• High energy experiments• Precision experiments

However, many open questionsHowever, many open questions

Exactly three generations? ~ 30 free parameters?Matter predominant?Sources of CP violation? Dark matter and dark energy?

Moreover, problems remainMoreover, problems remain

­ GravityGravity not included in the SM ­ No combined theory of Gravity and Quantum Mechanics

TTrapped rapped RRadioactive adioactive IIsotopes: sotopes: μμicro­ icro­ laboratories for Fundamental laboratories for Fundamental PPhysicshysics• weak interaction β­decay studies (21Na, …)• APV (Ra Ion)• Electric Dipole Moments (Ra Atom)

EDM Experiments WorldwideEDM Experiments WorldwideFundamental particles, nucleons, atoms, molecules and crystals

Limits of the EDM from some measurements

5 orders of magnitude larger than the Standard Model prediction.

Large window in new physics

2.9x10-26

1.6x10-27

4.5x10-17

3.7x10-17

1.6× 10­27••

199Hg

de (SM) < 10­37

molecules

EDM’s in time

Measuring an EDM of Neutral ParticlesMeasuring an EDM of Neutral ParticlesH = ­(d E + μ B) I/I

mI = 1/2

mI = ­1/2

ω1

ω2

d

EB

12 2=ω B dE

h

1ωµ d µ

EB

2ω2 2= B dE

h

2ω

2=E

( )1d4

­ω ωhd = 10­25 e cmE = 100 kV/cm

ω = 15 *10­5 rad/s ⇒⇒

From M. Romalis

Fortson GroupSeattle, Washington

Possible RoutesPossible Routes• CellsCells

high densitymotional fields average to zero long coherence times

• TrapsTraps ??no motional electric field, higher densitylong storage time → long observation timesultra high vacuum → high electric fields possiblesmall sample region → homogeneity

• New SystemsNew SystemsNew production facilities for short lived isotopes

• BeamsBeams ultra high vacuum leakage current suppression higher electric fields coherence time limited by length of beam

What about Radium?What about Radium?• A=88, alkaline earth element• Ground state [Rn] 7s2 1S0

• No stable isotope • 226Ra, τ 1/2= 1600 yrs, 1g RaCl ­> Activity of 1Ci

• Interesting isotopes• 225Ra, I=1/2, τ 1/2 = 14.7 d

• 223Ra, I=3/2, τ 1/2 = 15 d

• 213Ra, I=1/2, τ 1/2 = 2.7 min

Radium Spectroscopy DataRadium Spectroscopy DataRadium hollow cathode, large grating spectrometer

Ebbe Rasmussen, Z. Phys, 87, 607 , 1934; Z. Phys, 86, 24, 1933.Resolution ~ 0.05 A, 99 lines. 30 listed in NIST Database

[A]

Corrections in deduces energy levels, Level assignment. Some levels shifted by 640 cm­1 H.N. Russel, Phys. Rev. 46, 989 (1934)

1S0­1P1 1S0­3P1

[A]

Similar to Barium ⇒ identification as alkaline earth element

Nearly degenerate opposite parity 3P1 and 3D1 enhancement ~5000 e EDM

Why Radium?

3 3 3 32 1 1 2

3 32 1

| | | |( ) ( )

EDMD er P P H Dd

E D E P

Nearly degenerate opposite parity 3P1 and 3D2 enhancement > 10 4

Deformed charge distribution in some isotopes (225Ra). Nucleon EDM enhances 10≈ 2

Atomic energy level diagram of Ra

Density distribution of nuclear charge has mixed octupole and quadrupole deformation

V. A. Dzuba et al. Phys. Rev. A, 61, 062509 (2000)

J. Engel et al. Phys. Rev. C, 68, 025501 (2003)

482.7 nm

7s2 1S0

7s7p 1P1

7s7p 3P

7s6d 1D2

7s6d 3D 1 2

3

2

10

1

1

1

Radium Discharge and Hollow Cathode– Atom, E. Rasmussen, Z. Phys, 86, 24, (1933) – Ion, E. Rasmussen, Z. Phys, 87, 607, (1934)

Absorption Cell• Rydberg series ­> ionisation potential

– F.S.Tompkins, B. Ercoli, Appl. Opt. 6, 1299 (1968)

Laser Spectrocopy– @Isolde:

• 7s2 1S0­7s7p 1P1, 1S0­3P1, and 3P2­3D3

– S.A. Ahmad et al., Phys. Lett. B 133, 47 (1893) & Nuclear Physics A483, 244 (1988).

– K. Wendt et al., Z. Phys. D 4, 227 (1987).

– Argonne National Lab• 3D1­1P1 transition

– J.R. Guest el al., Phys. Rev. Lett. 98, 093001 (2007)

Periodic Table of ElementsPeriodic Table of Elements

TRIµ P

482.7 nm321

714 nm

1S0

1P1

3P

1D2

3D

2

10

1428 nm1488 nm

2.8 µ m

Leak rate without repumping

350 : 1Radium

Laser Cooling of Radium and Barium

553.7 nm

1S0

1P1

1D2

3D 1

23

1500 nm

1130 nm

1108 nm

Leak rate without repumping

330 : 1

Barium

3P210

Comparison of Comparison of Alkaline­EarthAlkaline­Earth ElementsElements

Be Mg Ca Sr Ba RaAlkaline earth elements

1

102

104

106

108

1010

∆v

[m/s

]

400 m/s

Cooling on 1S0 1P1: ∆ v = vrecoil*nscatter

Radium intercombinationline

Preliminary Transition Rates as calculated by K. Pachucky (also by V. Dzuba et al.)

Trappist’s ViewTrappist’s View

3*104 s­1

2.2*108 s­1

7s2 1S0

7s 7p 1P1

7s 7p 3P

7s 6d 1D2

7s 6d 3D 1 2

3

2

1

0

1*105 s­1

3*105

1.6*106 s­1

4*103 s­1

CoolingTransition

Repumping necessary

Weaker line, second stage cooling

Repumping

Competition at Argonne National Lab R. Holt, Argonne @ Lepton Moments 2006:

Trapping efficiency Trapping efficiency < 10< 10­6­6, , ~ 20 atoms in trap~ 20 atoms in trapJ.R.Guest et al., PRL 98, 093001 J.R.Guest et al., PRL 98, 093001 (2007)(2007)

Limited by cooling and Limited by cooling and trapping on trapping on intercombination lineintercombination line

BariumBarium

coil­I

coil­II

λ1, λ2, λ3

λ 1, λ IR2, λ IR3

atomic beam

I

I

|L>

|L>

|L>

|L>

|R>

|R>

λ1, λ2,

λ3

λ1, λ2,, λ3

λ IR1

x

y

z

λ IR2, λ IR3

PMT

λ /4

λ /4

λ /4 Velocity

Barium MOTBarium MOT

Pmt with filter at λ1 or λB

λ1

Ba Oven~ 820°K

λ3

diode laser

λir3

fiber laser

λir2

fiber laser

λit3

fiber laser

λir2

diode laser

λir1

diode laser

trapping laser λ1

λ /4λ /4

λ /4λ /4

mag. field coils

Vertical MOT beamnot shown

1500 nm, 5 mW, δ = ­80 MHz1130 nm, 25 mW, δ = ­105 MHz

1500 nm (15 mW, δ= 0 MHz)1130 nm (40 mW, δ= 0 MHz)

Slowing beam25 mW,

δ = ­220 MHz

90 mW

10 mW

MOT beams 20 mW, Ø=12 mmδ = ­10 MHz

Laser SetupLaser Setup

­4 ­2 0 2 4 60

0.5

1

1.5

2

2.5 x 105

Time [s]

Cou

nt r

ate

[1/s

]

Decay time 1.10(5) s

ττ MOTMOT~1s at 10­8mbarAtom losses in dark statesTrapping laser Intensity I­3 ­> photoionisation

P=4 10­9mbar

­500 ­250 0 250 50040

50

60

70

80

90

100

110

120

130

140

150

Longitudinal velocity of the atoms [m/s]

3 D1­1 S 0 F

luor

esce

nce

[Cou

nts/

s]

­500 ­250 0 250 50040

50

60

70

80

90

100

110

120

130

140

150

Longitudinal velocity of the atoms [m/s]

3 D1­1 S 0 F

luor

esce

nce

[Cou

nts/

s]

Results of trapping:about 1% capture of full velocity spectrum 1.5 s trap lifetime Improvements possible:

• Increase laser power in infra red (OPO)• Transverse cooling• Frequency broadening cooling laser• …

Building laser system for Radium trapping­100 ­50 0 500

2

4

6

8

10

12 x 105

Detuning [MHz]

1 P 1­1 S 0 Flu

ores

cenc

e [C

ount

s/s]

MOT signal

Doppler­free beam signal (*100)

MOTMOT

S. De, L. Willmann, 3 Oct 2007

Trapping of Barium AtomsTrapping of Barium Atoms

λ = 659.7 nm

5d6p 3D1

λ = 413.3 nm

λ = 667.7 nm

Two Photon (Raman) transitions

Rabi frequencyΩ ge = <ger.E0 e> ħer – electric dipole operatorE0 ­ Electric field

6s6p 1P1

Λ − System

6s2 1S0

6s5d 1D2

1500.4 nm

553.7 nm

1

2

3

Ω 12

Ω 23

∆

Ω 13 In case of two coherent laser field (for ∆ >> Ω 12,Ω 23)

Ω 13 = Ω 12Ω 23/2∆

5d2 3D2o

Example 3D1 state

Large population of metastable statesBut: atoms remain in MOT

Two Photon (Raman) transitions

0 500 15000

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

Detuning 659.7nm laser [MHz]

Nor

mal

ized

1 P 1­1 S 0flu

ores

cenc

e fr

om M

OT

10000

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

Detuning 659.7nm laser [MHz]

Nor

mal

ized

1 P 1­1 S 0flu

ores

cenc

e fr

om M

OT

Testing CalculationsTesting Calculations

MOT: Lifetime of MOT: Lifetime of 33FF22 state state 3D2­3D2

o @ 667nm pulse populated 3F2 state

τ = 190µ s ~ 93 % cascading back into cooling cycleCalculations of energy levels and transition ratesfor barium and radiumV.A. Dzuba and V.V. Flambaum, arXiv:physics/0610119

Other Publication~ 68 % cascading back

­1.5 ­1 ­0.5 0 0.5 1 1.5 2

0.7

0.75

0.8

0.85

0.9

0.95

1

Time [micro­s]

Norm

ali

zed

MO

T s

ign

al

Time [ms]

MOT: Lifetime of MOT: Lifetime of 33FF22 state stateM

OT

Flu

ores

cenc

e

3D2­3D2o @ 667nm pulse populated 3F2 state

1ms

τ = 130(25) µ s

Tra

nsfe

r to

3 F2

Loss to other states

6% losses from cooling cycleExcellent agreement with recent calculation

Isotope shifts: 5d6s Isotope shifts: 5d6s 33DD11 – 6s6p – 6s6p 11PP11 transition transition

I = 0 I = 3/2

138 B

a

137Ba

135Ba

134 B

a

136 B

a

Isotope selective population with intercombination lineCoupling to nuclear spin

U. Dammalapati et al., arXiv:0805.2022

Isotope shifts

∆ ν IS = ∆ ν NMS + ∆ ν SMS + ∆ ν FS Normal mass

shift specific massshift

Field shift

F δ <r2>(ν me/mp + FSMS ) (A1 – A2)/A1A2

FSMS electron correlation part

Modified shift

∆ ν M = ( ∆ ν SMS + ∆ ν FS ) A1A2 /(A1 – A2)

6s­6p transition

5d­6p transition

Modified shifts for isotope pairs (King plot)

Different slope with odd isotopes

Result of core polarisation

P. Grundevik et al., Z. Phys. A 312, 1 (1983).

300 kBcl 229Th source

104 225Ra/s

Offline Setup of 225Ra for Spectroscopy

ion pump

ion pump

gate valve

225Ra15 days

225Ac10 days

Fr, At, Bi…~ 4 hoursα αβ

229Th7340 yrs

Offline Atomic Beam of 225Radium

225Ra40.0 keV

221Fr218.1 keV 213Bi

440.5 keV

≈ 104 /s/cm2Inside oven ≈3.6*105 Bcl

229Th 225Raα­decay7340 y 14.9 d

Barium MOT

capture velocity 30m/s, 30G/cm number of atoms in the trap ~ 105­106

capture efficiency ~ 0.5% of full velocity distribution life time of the MOT ~1.5 s, depends on laser intensity temperature of the cloud 13(1) mK

Lifetime and decay

Summary

Isotope shifts of 5d6s 3D1,2 – 6s6p 1P1 transition

strong core polarization effects

Radium is attractiveLaser cooling strategy, go for it

G.P. Berg, J. v.d. Berg, U. Dammalapati, S. De, P.G. Dendooven, O Dermois, G.

Giri, R. Hoekstra, D.J. v.d. Hook, K. Jungmann,

W. Kruithof, T. Middelmann, A. Mol, R. Morgenstern, G. Onderwater,

A. Rogachevskiy, M. Sohani, M. Stokroos, M. da Silva, R Timmermans, E. Traykov,

O.O. Versolato, L. Wansbek, U. Wegener, L Willmann and H W Wilschut

Trapped Radioactive Isotopes: µ icro­laboratories for Fundamental Physics

MOTMOT

MOTMOT

Magnetic separatorMagnetic separator Production targetProduction target

Thermal IoniserThermal Ioniser

RFQ cooler/buncherRFQ cooler/buncher

D

D

Q

Q

DD

Q

QQ

QQ

Q

AGORAGOR

≥≥ 100 MeV100 MeV≤≤ 10 keV10 keV≤≤ 100 neV100 neV

MOTMOT

MOTMOT

MOTMOT

MOTMOT

Magnetic separatorMagnetic separator Production targetProduction targetMagnetic separatorMagnetic separator Production targetProduction target

Thermal IoniserThermal Ioniser

RFQ cooler/buncherRFQ cooler/buncher

Thermal IoniserThermal Ioniser

RFQ cooler/buncherRFQ cooler/buncher

D

D

Q

Q

DD

Q

QQ

QQ

QD

D

Q

Q

DD

Q

QQ

QQ

Q

AGORAGORAGORAGOR

≥≥ 100 MeV100 MeV≤≤ 10 keV10 keV≤≤ 100 neV100 neV Barium TrappingS. De

U. DammalapatiJ. v.d. Berg

T. MiddelmannK. Jungmann

LW

Radium SpectroscopyS. De

A. MolK. Jungmann

LW

TRIµ P Group

229Th 225Raα­decay7340 y 14.9 d