Search for a permanent EDM using laser cooled radioactive atom

Abstract

Abstract. An Electric Dipole Moment (EDM) of the elementary particle is a good prove to observe the phenomena beyond the Standard Model. A non-zero EDM shows the violation of the time reversal symmetry, and under the CPT invariance it means the CP violation. In paramagnetic atoms, an electron EDM results in an atomic EDM enhanced by the factor of the 3rd power of the charge of the nucleus due the relativistic effects. A heaviest alkali element francium (Fr), which is the radioactive atom, has the largest enhancement factor K ~ 895. Then, we are developing a high intensity laser cooled Fr factory at Cyclotron and Radioisotope Center (CYRIC), Tohoku University to perform the search for the EDM of Fr with the accuracy of 10 -29 e・cm. The important points to overcome the current accuracy limit of the EDM are to realize the high intensity Fr source and to reduce the systematic error due to the motional magnetic field and inhomogeneous applied field. To reduce the dominant component of the systematic errors mentioned above, we will confine the Fr atoms in the small region with the Magneto-Optical Trap and optical lattice using the laser cooling and trapping techniques. The construction of the experimental apparatus is making progress, and the new thermal ionizer already produces the Fr of ~10 6 ions/s with the primary beam intensity 200 nA. The developments of the laser system and optical equipments are in progress, and the present status and future plan of the experimental project is reported. IntroductionTo explore the mechanism responsible for the generation of observed matter-antimatter asymmetry in the Universe, the research on fundamental symmetry violations and various fundamental interactions using the laser cooled and trapped atoms is being promoted. The understanding of how the symmetry between the matter and antimatter was broken during the evolution of the early universe requires laboratory experiments which search for symmetry violations in the elementary particles such as quarks and leptons; one such phenomenon of our interest is the intrinsic electric dipole moment (EDM) of either elementary or composite systems. The non-zero observation of EDM provides the direct and conclusive signatures of the violation of time-reversal symmetry. The study of EDM also paves a way for the continuing quest for the ultimate theory of the Universe and it has a great potential in uncovering many mysteries which have been puzzling the mankind for ages such as the very survival of ourselves amidst many cosmic catastrophes such as a complete annihilation of matter and antimatter in the Universe. Using the extreme quantum states of matter at the low-energy scales we study the high-energy physics related to the phenomena which are thought to have happened in various epochs in the very early Universe.

Gauge invariant Barr-Zee type contributions to fermionic EDMs in the two-Higgs doublet models

“…experiments sensitivities on d e Fr [18] 1 × 10 −29 e cm YbF molecule [19] 1 × 10 −30 e cm WN ion [20] 1 × 10 −30 e cm Table 2. Future prospects on electron EDM.…”

Discrimination of dark matter models in future experiments

“…Blue chain line shows the constraint from ACME experiment. Solid turquoise line shows future prospect of measurement of Fr atom [45]. Dotted turquoise line shows future prospect of measurement of YbF molecule and WN ion [46,47].…”

Francium: Tool for Fundamental Symmetry Investigations

“…Francium (Z = 87), a group I element is a radioactive heavy metal and is being used for different experimental investigations such as atomic parity violation [13,14], search for an electron permanent electric dipole moment [15] and anapole moment [16,17]. Laser cooling and trapping of different Fr isotopes have been demonstrated [13,14,18,19].…”