Zheng-Tian Lu Physics Division, Argonne National Laboratory - PowerPoint Presentation

Slide1

Zheng-Tian LuPhysics Division, Argonne National LaboratoryDepartment of Physics, University of Chicago

Search for a Permanent Electric Dipole Moment (EDM)

of Radium-225

T

EDM

Spin

EDM

Spin

_

+

P

EDM

Spin

_

+

+

_Slide2

More CP-Violation Mechanisms?

Supersymmetry

More particles

 More CP-violating phases

Strong CP problem

CP-violating phase in Quantum Chromodynamics

Matter-antimatter asymmetry

Require additional CP-violation mechanism(s)

CP

T

=Slide3

Intensity Frontier Workshop, Dec 2011, www.intensityfrontier.org

Convenors

for nuclear physics: Haxton, Lu, Ramsey-Musolf

“The existence of an EDM can provide the “missing link” for explaining why the universe contains more matter than antimatter.”

“A nonzero EDM would constitute a truly revolutionary discovery.”

-- Nuclear Science Advisory Committee (NSAC) Long Range Plan (2007)

“The non-observation of EDMs to-date, thus provides tight restrictions to building theories beyond the Standard Model.” -- P5 report : The Particle Physics Roadmap (2006)

Priorities according to

Nima

Arkani-Hamed

,Institute for Advanced StudySlide4

EDM Searches in Three Sectors

Nucleons (n, p)

Diamagnetic atoms

(Hg

, Ra, Rn)

Electron in paramagneticmolecules (

YbF, ThO)

Quark EDM

Quark

Chromo-EDM4 Fermion, 3 Gluon

Electron

EDM, Electron-Quark

Physics beyond the Standard Model:SUSY, etc.

Sector

Exp

Limit

(e

-cm)

Method

Standard

ModelElectron9 x 10-29ThO in a beam10

-38Neutron3 x 10-26UCN in a bottle

10-31199Hg3 x 10-29

Hg atoms in a cell10

-33

M. Ramsey-Musolf (2009)Slide5

1

S

0

Ds

Rg

Cn

Uut

Fl

Uup

Lv

UusUuo

1

S

0Slide6

Schiff moment of

225

Ra,

Dobaczewski

, Engel, PRL (2005)Schiff moment of

199Hg, Dobaczewski, Engel

et al., PRC (2010)

Isoscalar

Isovector

Skyrme

SIII

300

4000

Skyrme

SkM

*

300

2000

Skyrme

SLy4

700

8000

Enhancement Factor: EDM (

225

Ra) / EDM (

199

Hg)

Closely spaced parity doublet

–

Haxton &

Henley, PRL

(1983)Large Schiff moment due to

octupole deformation – Auerbach, Flambaum & Spevak, PRL (1996)

Relativistic atomic structure (225Ra /

199Hg ~ 3) – Dzuba, Flambaum, Ginges,

Kozlov, PRA (2002)

EDM of 225Ra enhanced and more reliably calculated



-

= (|a



- |b



)/



2



+

= (|a



+ |b



)/



2

55 keV

|

a



|

b



Parity doublet

“[Nuclear structure] calculations in Ra are almost certainly more reliable than those in Hg.”

–

Engel, Ramsey-Musolf, van

Kolck

,

Prog

. Part.

Nucl

. Phys. (2013

)

Constraining parameters in a global EDM analysis.

–

Chupp, Ramsey-Musolf

,

arXiv1407.1064

(

2014)Slide7

Efficient use of the rare

225

Ra atoms

High electric field (> 100 kV/cm) Long

coherence time (~ 100 s) Negligible “v x E” systematic

effectEDM measurement on

225

Ra in a trap

Transverse

cooling

Oven:

225

Ra

Zeeman

Slower

Magneto-optical

Trap (MOT)

Optical dipole

trap (ODT)

EDM

measurement

225

Ra:

I = ½

t

1/2

= 15 d

Collaboration of Argonne, Kentucky, Michigan State

Statistical

uncertainty

100 kV/cm

10%

100 s

10

6

100

d

Long-term goal:

d

d

= 3 x 10

-28

e

cmSlide8

ApparatusArgonne National Lab8Slide9

Emax

= 75 kV/cmE-field spatial variation < 1%/mm

B ~ 10

mGauss

B-field spatial variation < 0.1%/cmB-field t

emporal variation < 0.01% (50sec)

EDM (d) MeasurementSlide10

Radium EDM Data

d

Ra-225

= (-0.5 ± 2.5

stat

±

0.2

syst

) × 10

-22

e-cm |dRa-225| < 5.0

× 10-22 e-cm (95%

confidence)Oct. 2014

Dec. 2014Slide11

First

EDM measurement on

octupole deformed nuclei;First EDM measurement using cold atoms. Slide12

Outlook2015 - 2016

Longer trap lifetime;Implement STIRAP – more efficient way to detect spin;

2016 - 2018, blue upgrade – more efficient trap;Five-year goal (before FRIB): 10

-26 e cm;2020 and beyond (at FRIB): 3 x 10-28

e cm;Far future: search for EDM in diatomic moleculesEffective E field is enhanced by a factor of 10

3;Reach the Standard Model value of 10-30 e cm.Slide13

Absorption Detection of Spin State

483 nm

1

S

0

1

P1

Photons scattering events

2-3 photons per atom

Signal-to-noise Ratio

For 100 atoms, SNR ~

0.2mF = -1/2

+1/2F = 1/2

F = 1/2F = 3/2Slide14

STIRAP (stimulated Raman adiabatic passage)

483 nm

1429

nm

1

S

0

1

P

1

3

D

1

Stimulated, Adiabatic process

No fluorescencemF

= -1/2+1/2

F = 1/2F = 1/2

F = 3/2Slide15

Absorption Detection on a Cycling Transition

483 nm

1

S

0

1

P

1

3

D

1

Photons scattering events

2-3 photons per atom100-1000 photons per atom

Signal-to-noise RatioFor 100 atoms, SNR ~ 0.2For 100 atoms, SNR ~ 10

mF = -1/2

+1/2F = 1/2

F = 1/2F = 3/2

m

F = +3/2Slide16

7p

1P1

Trap, 714 nm

7s

2

1S0

7p

3

P1

420 ns

6 ns

6d

3

D

1

Pump #1

7p

1

P

1

Slow & Trap

, 714 nm

7s

2

1

S0

7p

3P1

420 ns

6 ns

6d

3

D

1

Pump #1

6d

1

D

2

430

m

s

6d

3

D

2

Improve trapping efficiency with a

blue upgradeSlide17

Scheme

1

st slowing laser: 483 nm (strong)

2nd

slowing laser: 714 nm

3 repumpers: 1428 nm, 1488 nm, 2.75

mm171Yb

as

co-magnetometer * 225

Ra and 171Yb trapped, < 50 mm apart

Benefits100 times more

atoms in the trapImproved control on

systematic uncertainties

7p 1P

1

Trap, 714 nm

7s2

1S0

7p 3

P1

420 ns

6 ns

6d

3

D

1

Pump #1

7p

1

P

1

Slow & Trap

, 714 nm

7s

2

1S0

7p

3P1

420 ns

6 ns

6d

3

D

1

Pump #1

6d

1

D

2

430

m

s

6d

3

D

2

Slow,

483 nm

Pump #2

Pump #3

KVI

b

arium trap

S. De

et al

. PRA (2009)

Improve trapping efficiency with a

blue upgrade

Atom Velocity

Atom Flux

60

m/s

310 m/sSlide18

18

225

Ra Yields

229

Th

7.3

kyr

225

Ra15 d

225Ac10 d

Fr,

Rn,…~4 hr

b

233U159 kyr

a

a

a

Presently available

National Isotope Development Center, ORNLDecay daughters of

229Th 225

Ra: 108 /sProjectedFRIB

(B. Sherrill, MSU)Beam dump recovery with a 238U

beam 6 x 109 /s

Dedicated running with a 232Th beam 5

x 1010 /s

ISOL@FRIB (I.C. Gomes and J. Nolen, Argonne)Deuterons on thorium target, 1 mA x 400 MeV = 400

kW 1013

/s

MSU K1200 (R. Ronningen and J. Nolen, Argonne)Deuterons on thorium target, 10

uA x 400 MeV = 4 kW 1011 /sSlide19

Kevin

BaileyPeter

MuellerTom

O’ConnorCold Atom Trappers

Argonne: Kevin Bailey, Michael Bishof, John Greene

, Roy Holt, Nathan Lemke, Zheng-Tian Lu, Peter Mueller, Tom O’Connor, Richard ParkerKentucky: Mukut Kalita,

Wolfgang KorschMichigan State: Jaideep SinghNorthwestern:

Matt DietrichMichaelBishof

RichardParker

MukutKalita

RoyHolt

Z.-T.LuSlide20

Optical Dipole Trap

Fiber laser:

l

= 1550 nm, Power = 40 Watts

Focused to 100

m

m

 trap depth

400

m

K

EDM in an optical dipole trap –

Fortson & Romalis (1999)

v

x E , Berry’s phase effects suppressed Cold scattering suppressed between cold Fermionic atoms

Rayleigh scat. rate ~ 10-1 s-1

; Raman scat. rate ~ 10-12 s-1

Vector light shift ~ mHz

Parity mixing induced shift negligible Conclusion: possible to reach 10-30 e cm for 199HgSlide21

Trap Lifetimes

Magneto-Optical Trap (MOT)i

n the first trap chamberOptical Dipole Trap (ODT)in the EDM chamber

Sideview

Head-on

view

ODT 0.04 mm

MOT & ODTSlide22

Systematics

Systematic effects much smaller than Statistical error for nowNo corrections needed

Systematic Effect ΔdRa-225 (e-cm)

Imperfect E-field reversal1 × 10

-23Blue laser frequency correlations< 10

-25External B-field correlationsCurrent supply

correlationsE-field pulsing

1D MOT Coil

MagnetizationLeakage

currentOptical lattice power correlations

E x v effects

Stark interferenceBerry’s phaseSlide23

E2 Systematic

3 mCi Run (October)

6 mCi Run (December)

dE-squared

syst ≤ 0.2× 10

-22 e-cm d

E-squared syst ≤ 0.05×

10

-22 e-cm Slide24

Actual Near Term Goal

N: # atoms detected

150 300

E: Effective E-field (kV/cm) 45 75

𝜏: Precession Time (s) 2 20

T

d

: Dead time (s) 48 48

T: Total time (s) 2

× 86,400 5

× 86,400

γatom:

Photons per atom 2.5 1,000

γlaser:

Photons per laser pulse 106 4

×108

EDM sens.

(e-cm)

3×10-22

4×10-25 d =

What the stat. sensitivity of our experiment could be!Slide25

T.

Chupp and M. Ramsey-

Musolf, arXiv.1407.1064Why a more sensitive radium EDM measurement is important to scienceSlide26

Preparation of Cold Radium Atoms for EDM

2006 – Atomic transitions identified and studied;

2007 –

Magneto-optical trap (MOT) of radium realized; 2010 – Optical

dipole trap (ODT) of radium realized; 2011 – Atoms transferred to the measurement trap;

2012 – Spin precession of Ra-225 in ODT observed;

2014 – First measurement of EDM of Ra-225.

J.R. Guest et al., PRL 98, 093001 (2007)

R.H. Parker et al., PRC 86, 065503 (2012)

N.D. Scielzo et al.,

PRA Rapid 73, 010501 (2006)

R.H. Parker et al., submittedSlide27

EDM (d) Measurement