Search for the electric dipole moment of the electron with thorium monoxide

Vutha, Amar C.; Campbell, W. C.; Gurevich, Yulia V.; Hutzler, Nicholas R.; Parsons, Maxwell F.; Patterson, David; Petrik, Elizabeth; Spaun, Ben; Doyle, John M.; Gabrielse, Gerald; DeMille, David

doi:10.1088/0953-4075/43/7/074007

Cited by 129 publications

(179 citation statements)

References 40 publications

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“…The measurements were carried out using a molecular beam of ThO, produced in an apparatus similar to one described elsewhere [7]. The apparatus uses helium buffer gas at 4 K to cool a pulse of ThO molecules (produced by pulsed laser ablation of ThO 2 ), which are extracted into a molecular beam and probed 30 cm downstream.…”

Section: Methodsmentioning

confidence: 99%

Magnetic and electric dipole moments of theH3Δ1state in ThO

et al. 2011

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The metastable H 3 1 state in the thorium monoxide (ThO) molecule is highly sensitive to the presence of a CP-violating permanent electric dipole moment of the electron (eEDM) [E. R. Meyer and J. L. Bohn, Phys. Rev. A 78, 010502 (2008)]. The magnetic dipole moment μ H and the molecule-fixed electric dipole moment D H of this state are measured in preparation for a search for the eEDM. The small magnetic moment μ H = 8.5(5) × 10 −3 μ B displays the predicted cancellation of spin and orbital contributions in a 3 1 paramagnetic molecular state, providing a significant advantage for the suppression of magnetic field noise and related systematic effects in the eEDM search. In addition, the induced electric dipole moment is shown to be fully saturated in very modest electric fields (<10 V/cm). This feature is favorable for the suppression of many other potential systematic errors in the ThO eEDM search experiment. Measurable CP violation is predicted in many proposed extensions to the standard model, and could provide a clue to the observed dominance of matter over antimatter in the universe [1]. The permanent electric dipole moment of the electron (eEDM) is a sensitive probe for flavor-diagonal CP violation in the lepton sector [2]. A number of experimental efforts are currently focused on searching for this elusive quantity [3]. Many of these experiments take advantage of the large internal electric field E mol experienced by valence electrons in a polar molecule [4]. Following the suggestion of Meyer et al. [5], states with a 3 1 character in heavy molecules are being used in several new eEDM experiments [6][7][8]. In addition to a large intrinsic eEDM sensitivity, there are two key attractive features of this kind of molecular state for eEDM searches: closely spaced opposite parity doublets ( -doublets) [5,9] and small magnetic moments [5,10]. The -doublets enable the molecule to be completely polarized in small electric fields. The fully polarized molecule accesses the full eEDM sensitivity of the molecule, while suppressing E-field-induced systematic errors such as those due to leakage currents and geometric phases [7,11,12]. The extremely small magnetic moment of the H 3 1 state makes the molecule less sensitive to effects arising from fluctuating B fields and motional ( v × E/c 2 ) magnetic fields [7]. Here we report measurements of both of these key parameters in the H state of ThO. I. EXPERIMENTAL SETUPThe measurements were carried out using a molecular beam of ThO, produced in an apparatus similar to one described elsewhere [7]. The apparatus uses helium buffer gas at 4 K to cool a pulse of ThO molecules (produced by pulsed laser ablation of ThO 2 ), which are extracted into a molecular beam and probed 30 cm downstream. The lowest rovibrational level (v = 0,J = 1) in the H state was populated by optical pumping from the ground electronic X 1 + (v = 0,J = 1) state via the higher-lying, short-lived A 3 0 + (v = 0,J = 0) state. It * amar.vutha@gmail.com was subsequently probed a few millimeters downstream by e...

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Section: Methodsmentioning

confidence: 99%

Magnetic and electric dipole moments of theH3Δ1state in ThO

et al. 2011

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“…Recently, the limit of the electron EDM could already be matched with such a technique in YbF to ∼ 1.05 −27 e·cm [38]. Using ThO, the ACME experiment [53,54] is expected to produce a highly competitive result very soon.…”

Section: Schiff--momentmentioning

confidence: 99%

Round Table: Resolving Physics BSM at Low Energies

Gardner¹,

Cirigliano²,

Fierlinger³

et al. 2013

Proceedings of XTH Quark Confinement and the Hadron Spectrum — PoS(Confinement X)

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“…There are several applications of intense molecular beams, from experiments attempting to measure the electron's electric dipole moment [3,4] and variation of fundamental constants [5], to experiments exploring cold reactions relevant to interstellar cloud chemistry [6]. In most of these experiments, removing the mean forward velocity is critical to taking full advantage of the molecular source.…”

Section: Introductionmentioning

confidence: 99%

Method for traveling-wave deceleration of buffer-gas beams of CH

et al. 2014

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Cryogenic buffer-gas beams are a promising method for producing bright sources of cold molecular radicals for cold collision and chemical reaction experiments. In order to use these beams in studies of reactions with controlled collision energies, or in trapping experiments, one needs a method of controlling the forward velocity of the beam. A Stark decelerator can be an effective tool for controlling the mean speed of molecules produced by supersonic jets, but efficient deceleration of buffer-gas beams presents new challenges due to longer pulse lengths. Traveling-wave decelerators are uniquely suited to meet these challenges because of their ability to confine molecules in three dimensions during deceleration and their versatility afforded by the analog control of the electrodes. We have created ground state CH(X 2 Π) radicals in a cryogenic buffer-gas cell with the potential to produce a cold molecular beam of 10 11 mol./pulse. We present a general protocol for Stark deceleration of beams with a large position and velocity spread for use with a traveling-wave decelerator. Our method involves confining molecules transversely with a hexapole for an optimized distance before deceleration. This rotates the phase-space distribution of the molecular packet so that the packet is matched to the time varying phase-space acceptance of the decelerator. We demonstrate with simulations that this method can decelerate a significant fraction of the molecules in successive wells of a traveling-wave decelerator to produce energy-tuned beams for cold and controlled molecule experiments.

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Search for the electric dipole moment of the electron with thorium monoxide

Cited by 129 publications

References 40 publications

Magnetic and electric dipole moments of theH3Δ1state in ThO

Magnetic and electric dipole moments of theH3Δ1state in ThO

Round Table: Resolving Physics BSM at Low Energies

Method for traveling-wave deceleration of buffer-gas beams of CH

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