Progress Towards Measurement of the Electron s s Electric Dipole Moment using the PbF Molecule ucn 2007

Transcription

1 Progress Towards Measurement of the Electron s s Electric Dipole Moment using the PbF Molecule ucn 2007 Neil Shafer-Ray, Funding sources for preliminary research: National Research Council (US) NATO SfP OU Office of the Vice President for Research Current funding: National Science Foundation DOE EPSCoR Laboratory-State Partnership

2 An EDM proportional to spin would also give CP Purcell, Ramsey PRA (1950.) ΔU = r r r r μ ( g B S + g E S) B μ B = MHz/G g = (16) Gabrielse,PRL 2006 g edm = (5) edm = e cm Commins, PRL, 2004

3 An EDM proportional to spin would also give CP 5 5 x 10-5 g EDM 5 x x x x Commins & coworkers, Tl, PRL, Hinds & coworkers, YbF, DAMOP, 2005 (Hoogeveen 1990) (Arnowitt 2001) Std. Mod. Super Sym.

4 Outline What are some of the current experiments being carried out to measure the e-edm? What is the OU group up to?

5 How the current limit on electron EDM is known Symmetry leads to a ±M degeneracy of any molecule or atom that is not broken by an electric field along the quantization axis. The existence of an electron electric dipole moment would break this symmetry. To search for an Major Difficulty: e-edm we will A Precision background structure look for magnetic calculations field are not necessary. ΔU=U +M U mimics an EDM. -M in a strong E field.

6 For an isolated electron, U The Commins Experiment with 1/2 (F=1, M=±1) Tl 2 P 1/2 r r r r = μ ( g B S + g E S) B edm For an atom or molecule in a strong electric field, g U sys edm E eff r r r r sys sys μ ( g B S + g E S) = 0 = 0 B edm for diamagnetic atoms for light atoms/molecules (Schiff's theorem.) E eff >> E lab for relativistic (heavy) atoms/molecules. Heavy paramagnetic atoms or molecules are sensitive to an e-edm. eff

7 The Commins Experiment with 1/2 (F=1, M=±1) Tl 2 P 1/2 ΔU h Tl = 2 ( 585)( 0.77) p h e E z (0.34) μb h B z enhancement factor geometric factors ΔU h Tl =.022mHz 10 pe e cm Ez volt / cm Bz 24 pg

8 Measurement of the e-edm e using paramagnetic molecules System (state) Tl ( 2 P 1/2 F=1) YbF (X 2 Σ,F=1) Commins Hinds E-field (kv/cm) e cm (mhz) e cm (ng) t coherence (ms) d limit (10-27 e cm) (1?) 1) Effective electric field is the internal field of the molecule. 2) Idea by Saunders (Atomic Phys, ,71). 3) Calculation of shift by N.S. Mosyagin, M.G. Kozlov, A.V. Titov, (J Phys B, 31, L763)

9 Differences between an atomic beam and a beam of paramagnetic molecules Beam Expected Flux Speed Distribution Tl(F=1, M =1) (from oven) /str/sec v(m/s) YbF(J=1/2, F=1, M =1) (from supersonic expansion) /str/sec Easy to lose in statistics what one gains in intrinsic sensitivity v(m/s)

10 System (state) E-field (kv/cm) e cm (mhz) e cm (ng) t coherence (ms) d limit (10-27 e cm) Tl ( 2 P 1/2 F=1) Commins YbF (X 2 Σ,F=1) Cs ( 2 P 1/2 F=3) PbO (a 3 Σ,F=1) Hinds (Hinds) Hunter PbF (Shafer- (X 2 Π 1/2, F=1) Ray) HfF + ( 3 Δ 1 ) (Weiss) (Gould) (DeMille) (1?) , ? ? ~ to ~1 volt RF (Cornell) ~10 ~200 ~10 ion trap

11 The OU PbF edm experiment System (state) E-field (kv/cm) e cm (mhz) e cm (ng) t coherence (ms) d limit (10-27 e cm) PbF (Shafer- (X 2 Π 1/2, F=1) Ray) to

12 g factor of the X 1 ( 2 Π 1/2 ) J=1/2, Ω + F=1, M F =1 state of PbF g-factor can be tuned to zero! Shafer-Ray, PRA,73, g 1 G ) ( g 1 (2G / 3)

13 Schematic of PbF e EDM measurement optical polarization (create M=0 state) RF ob e + high-field region REMPI detection region (probe M=0 state) pr PbF molecular beam source RF

14 First things first: Production and detection of PbF Pb / F 2 flow reactor: Operational Temperature 1200K Pb +MgF 2 reactor: Operational Temperature 1200K

15 Schematic of PbF e EDM measurement optical polarization (create M=0 state) RF ob e + high-field region REMPI detection region (probe M=0 state) pr PbF molecular beam source RF

16 Basic of Energy Level Structure of PbF 6 Stark Effect in PbF HX 2 Π 1ê2 L optical polarization U H c m 1L J=7/2 J=5/2 J=3/2 J=1/2 F = I+J (I=I Fluorine =1/2) 2 Ω - Ω + RF mixing M= E HkVêcmL ~ MHz F 1, M =1 F 1, M= mHz Our experiment probes these three states.

17 Graphical Description of the Commins e-edm Experiment STATE SELECTIVE LASER RADIATION E P(θ,φ) = probability of finding the system In the state M=F when quantization axis is in the direction of θ,φ. Appendix of Shafer-Ray, Orr-Ewing, Zare, J. Phys. Chem. 99, 7591, (1995.) PbF( 2 Π 1/2 F=1), PbF( incoherent 2 Π 1/2 F=1), combination of 1,1>, 1,0> and 1,0> 1,-1> states

18 1+1 X 12 Π 1/2 B 2 Σ 1/2 REMPI of PbF McRaven, Poopalasingam, Shafer-Ray, PRA. 75, (2007.) 5.0 (0,0) band OU data, 2005 ν X->A /c (cm -1 ) energy (ev) nm nm PbF + A 2 Σ 1/2 B 2 Σ 1/2 X 2 Π 1/ R(Bohr)

19 McRaven, Poopalasingam, Shafer-Ray, PRA. 75, (2007.) 1+1 X 12 Π 1/2 B 2 Σ 1/2 REMPI of PbF I.P. 7.55eV

20 f 1 c/436.8nm+ f 2 c/476.7nm+ f 3 c/532nm 206 Pb 19 F 207 Pb 19 F 208 Pb 19 F Chris PbF + PbF SIVA

21 REMPI Detection /Polarization of PbF 5.0 X-A FREQUENCY RAW DATA TAKEN, DECEMBER 2006 [R-P] e [R-Q] e [R-R] e J=5/2, Ω + J=3/2, Ω - J=1/2, Ω + energy (ev) nm LASER A-E' LASER X-A PbF + E' 2 Σ 1/2 A 2 Σ 1/2 X 2 Π 1/2 A-E' FREQUENCY State of PbF uniquely sensitive to the e-edm R(Bohr)

22 Schematic of PbF e EDM measurement optical polarization (create M=0 state) PbF molecular beam source REMPI detection region (probe M=0 state) pr RF ob e + high-field region RF A 2Σ1/2 (F=1) X1 2Π1/2 (F=1) M=0 M=0 M =1 M =1

23 Schematic of PbF e EDM measurement optical polarization (create M=0 state) RF ob e + high-field region REMPI detection region (probe M=0 state) pr PbF molecular beam source RF

24 First RF Cavity B RF M =1 B RF M=0

25 First RF Cavity B RF M =1 B RF M=0

26 Schematic of PbF e EDM measurement optical polarization (create M=0 state) PbF molecular beam source REMPI detection region (probe M=0 state) pr RF ob e + high-field region RF M =1 X1 2Π1/2 (F=1) BRF1 M=0

27 Schematic of PbF e EDM measurement optical polarization (create M=0 state) PbF molecular beam source REMPI detection region (probe M=0 state) pr RF ob e + high-field region RF ψ= 1,1 + e iδut / h 1, α e iut / h 1,0

28 Evolution of PbF in Measurement Region iδut / h,1 + e 1, 1 ψ = + α e 2 1 iut / h 1,0 E,B M =1 M=0 ΔU (rotation) U (shake) ΔU = 2 μ B gb + 2 μ B g EDM E eff mhz U 50MHz

29 Schematic of PbF e EDM measurement optical polarization (create M=0 state) PbF molecular beam source REMPI detection region (probe M=0 state) pr RF ob e + high-field region RF BRF 1 = Bo [i ] cos ωt BRF 2 = Bo [cos φ i + sin φ j ] cos((ω + Δω )t ) X1 2Π1/2 (F=1) M =1 BRF2 Measure I(t)~Io+ I1cos2Δωt M=0

30 θ B RF2 Second RF Cavity Probability of population transfer to M=0 depends on both 2μBt θ = ( gb + gedm Eeff ) + φ h and phase of RF modulation wrt phase of shake. 1+cos(2θ) time ave signal Lock E field to narrow error signal. Alternate angle between B sensitivity to gb + g 1+ cos 2θ φ = mπ / 4 EDM E RF1 eff and B : RF2 4μBt = 1± sin( h h/t h/t RF between φ = ( gb + g demodulated error signal EDM E )) ν RF ν M = 0 M = 1 t/t RF 100 m( π / 4) to obtain first - order eff

31 Schematic of PbF e EDM measurement optical polarization (create M=0 state) PbF molecular beam source REMPI detection region (probe M=0 state) pr RF ob e + high-field region RF BRF 1 = Bo [i ] cos ωt BRF 2 = Bo [cos φ i + sin φ j ] cos((ω + Δω )t ) sensitivity to gedme+gb lock electric field to a clock standard I (t )dt sin(2δω t ) I (t )dt Measure I(t)~Io+ I1cos2Δωt

32 optimistic estimate: Estimated Sensitivity E eff = effective field = 60GV/cm (Kozlov) τ=coherence time ~ 3ms T=collection time ~ 1 day R=Expected Count Rate: ~1MHz p e (h/τ)(rt) -1/2 (E eff -1 ) 3x10-30 e cm We expect a 1-day sensitivity that is times smaller than the current limit of e cm in an experiment designed to dramatically reduce systematic errors.

33 Status of the eedm experiment We have found a system for which the effect of background magnetic fields may be suppressed by seven orders of magnitude. We have developed a source of PbF as well as an extraordinarily sensitive state selective REMPI detection scheme. We have designed a Ramsey resonance experiment to take advantage of the small and tunable g factor of PbF.

34 THANKS TO: Undergraduate Students: Graduate Students: Chris Crowe, Dustin Combs, Chris Bares, Leah Trafford,Erik Villenti Chris McRaven, Sivakumar Poopalasingam, Milinda Rupasinghe Professor George Kalbfleisch: March 14, September 12, 2006

35 And thanks to the e-edm COLLABORATION The University of Oklahoma Neil Shafer-Ray Kim Milton John Furneaux Petersburg Nuclear Physics Institute Victor Ezhov Mikhail Kozlov University of Latvia Marcis Auzinsch U Cal Berkeley Dmitry Budker BNL Chemistry Greg Hall Trevor Sears