Francium: Tool for fundamental symmetry

investigations

U Dammalapati Cyclotron and Radioisotope Center (CYRIC)

Tohoku University, Sendai

LEAP2016, Kanazawa, March 06-11, 2016

Outline

➢Discrete Symmetries Role in the Standard Model

➢Permanent Electric Dipole Moment in Atoms

➢Francium Advantages Sources/Production of Fr isotopes

➢Francium EDM project @ CYRIC Status of the experiment ➢Summary

Discrete SymmetriesIn the Standard Model of electro-weak interactions • Parity symmetry violation (β - decay) • CP violation → δKM in the SM (K & B-meson – decay)

CP violation ↔ T violation Insufficient for

Matter – Anti matter asymmetry

Searches for permanent Electric Dipole Moments (EDM) best probe for new sources of CP violation

EDMs violate - Parity - Time Reversal

Permanent Electric Dipole Moments

CP/T violation in SM yield EDMs << experimental limits

d - EDM µ - magnetic dipole moment F - Total angular momentum

Limit for electron EDM (ThO) d< 8.7 x 10–29 e cm The ACME Collaboration, Science 343, 269 (2014)

Francium: A good candidate T. M. Byrnes et al. Phys. Rev.A 59, 3082 (1999) Mukherjee et al., J. Phys. Chem. A 113, 12549 (2009)

K Jungmann

Francium: pros and cons

✓ Z3 law (heavier atoms are better)

✓Rich experimental information of energy levels and transitions ✓ Extensive information from theory ✓ Convenient laser sources ✓ Laser cooling and trapping demonstrated

• Radioactive • No long lived

isotopes & • small quantities

☺ Pros

☹ Cons

Cs

Tl

Fr

Rb

Byrnes et al., PRA 59, 3082 (1999) Mukherjee et al., JPC A113, 12549 (2009)

Fr: Sources and interesting isotopes

221Francium ➢Long lived 229Th, 225Ac source Lu et al. PRL 79, 994 (1997), Tandecki et al. JINST 9, P10013(2014)

Many Isotopes ➢ At accelerator facilities CYRIC@Tohoku (flux ~ 106/s) Sakemi et al. J. Phys. conf. ser. 302, 012051 (2011) LNL@Italy (flux ~ 106/s) Sanguinetti et al. Opt. Lett. 34, 893 (2009) TRIUMF@Canada ( flux ~ 109/s) Collister et al. PRA 90, 052502 (2014) ISOLDE, CERN ( flux ~ 109/s) Arnold et al. J. Phys. B 22, L391 (1989)

Isotope Half life (τ1/2) Nuclear spin (I)210Fr 3.2 min 6211Fr 3.10 min 9/2212Fr 20 min 5221Fr 4.8 min 5/2

Possible Routes

Cells ✓ high density motional fields average to zero long coherence times

Traps no motional magnetic fields, higher density long storage time → observation times ultra high vacuum → high electric fields small sample region → homogeneity New Systems New production facilities for short lived isotopes

Beams ✓ ultra high vacuum leakage current suppression -> higher electric fields coherence time limited time of flight motional magnetic fields

Graner et al. arXiv:1601.04339v2 (2016)

Parker et al. PRL114, 233002 (2015)

Hudson et al. Nature 473, 493 (2011)

8

Laser room

Ext. room

Cyclotron

Target room

930 AVF cyclotron(K=110 MeV)

Shield wall

18O5+ (100MeV)

Fr+ (keV)

Swinger magnet

Fr production

(197Au target)

… Electrostatic optics …

NeutralizerMOT

optical fiberFrancium project and facility @ CYRIC

H Kawamura

9

100M

eV

210Fr

Stancari et al., NIMA557(2006)390

Production cross section

18O5+

Fr+Einzel lens

Oven

Extraction electrode

197Au target ~1000oC

Ion source Fr yield - Extraction voltage dependence

~40% @ 5kV extraction

850Gold temperature [oC]

Fr c

ount

rate

[a.u

.]

2

4

900 10009500

solid

liquid

Fr yield - temperature dependence

~106pps extraction

Francium production and ionization

H Kawamura

Neutralization: MOT of neutralized Rb atoms

Time (s)

Pict

ure

brig

htne

ss

Y po

siti

on

106 ions/s

updo

wn

Curr

ent

Fluorescence from trapped Rb atoms

1000 K

300 K

up

down

Glass cell features: • Material: Quartz with AR coating • OTS (octadecyltrichlorosilane) coating to minimize sticking of atoms to the glass cell.

Ionization potential of Fr: 4.08 eV, Rb: 4.2 eV

Yttrium (Y) to neutralize ionsWork function of Y: 3.2 eV Temperature: ~ 1000 K

K Harada

Trapping - Ti:Sa Laser (718 nm) Coherent Verdi (532 nm) ＋ MBR110

210Fr

Repumping 718 nm

Trapping 718 nm

VerdiMBR110

30 mW (Toptica)

Custom ECLD

Repumping laser (718 nm)

Lasers and Spectroscopy for Fr-MOT

Iodine cell in oven

10 cmLock point

0.0 0.5Frequency [GHz]

Frequency modulation spectroscopy of Iodine

Sig

nal i

nten

sity

[arb

. uni

ts]

Frequency reference and stabilization: Iodine molecule

3 GHz

P(78) 1-9 band Presumed Fr trapping

frequencyK Harada

2015年3⽉月21⽇日 12

Rb magnetometerUses the nonlinear magneto-optical rotation (NMOR) effect with frequency modulated (FM) light. A magnetic field component parallel to the laser light is measured.

λ/23-axis coilPolarizer

magnetic shield

Bandpass filter

Analyzer Photo Diode

Lock-in Amplifier

5kHz FM laser light P = 150 µW r = 2 mm

Paraffin coated Rb vapor cell: 23 oC, 1010 atoms/cm3

Rot

atio

n an

gle

[mra

d]

Magnetic field [µT]

The best magnetic field sensitivity is 50 pT/(Hz)1/2

The shot-noise limit is lower than 3 fT/(Hz)1/2

● Shot-noise limit (SNL) ▲ Photon SNL ▲ Atomic SNL

Sho

t-noi

se li

mit

[fT/(H

z)1/

2 ]

Laser power [µW]

A Uchiyama

Electrodes for EDM measurementStrong electric field application (~ 100 kV/cm) and 3 dimensional laser light irradiation

Electrode: glass plate coated by ITO (tin-doped indium oxide)

Confirmation of electric field strength - Stark shift measurement of trapped Rb atoms

Glass plate coated with ITO

Measured shift 27(1) MHz of F = 2 to F’ = 1 transition at E = 20 kV/cm (1 cm gap between electrodes)

Frequency (MHz)

Abs

orpt

ion　（

Arb

. uni

ts)

27(1) MHz20 kV

0 kV

Preliminary

T Inoue

Transparent electrodes for laser light Good transmission for visible and near infrared light

Summary

✓Investigation: Discrete symmetries P/T violation through EDM searches

✓ Francium: A good candidate for electron EDM searches

✓ Status: Efficient use of radioactive samples

✓ Scope: Modern EDM experiments

Acknowledgements

K Harada T. Hayamizu

(Now at UBC, Vancouver)

T. Inoue H. Kawamura

M. Itoh A. Hatakeyama

Y. Sakemi

K. Sakamoto K. Kato T. Aoki S. Ito

A. Uchiyama

T. Aoki (Univ. Tokyo)

K. Asahi, T. Sato (Tokyo Inst. Tech.) T. Furukawa

(Tokyo Metropol. Univ.) T. Wakasa, H. P. Yoshida

(RCNP, Osaka Univ.) K. Imai

(JAEA)

Fr EDM members Collaborators