Search for an Electric Dipole Moment of the Electron

Nelson, Dylan; Schupp, A.A.; Pidd, R. W.; Crane, H. R.

doi:10.1103/physrevlett.2.492

Cited by 81 publications

(66 citation statements)

References 6 publications

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“…Quasimagnetic resonances for particles and nuclei moving in noncontinuous perturbing fields of accelerators and storage rings are considered in Sect. 6. Distinguishing features of quasimagnetic resonances in storage ring electric-dipolemoment experiments are investigated in Sect.…”

Section: Introductionmentioning

confidence: 99%

“…An exhaustive analysis of the spin evolution in storage ring electric-dipole-moment (EDM) experiments needs an advanced description of magnetic and quasimagnetic resonances. In this case, spin interactions of moving particles and nuclei with magnetic and electric fields are defined by the Thomas-Bargmann-Mishel-Telegdi (T-BMT) equation [3][4][5] or by its extension taking into account the EDM [6][7][8][9]. An investigation of quasimagnetic resonances caused by the EDM is important for planned experiments with a rf electric-field flipper and a rf Wien filter (see Refs.…”

Section: Introductionmentioning

confidence: 99%

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General classical and quantum-mechanical description of magnetic resonance: an application to electric-dipole-moment experiments

Silenko

2017

Eur. Phys. J. C

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A general theoretical description of a magnetic resonance is presented. This description is necessary for a detailed analysis of spin dynamics in electric-dipole-moment experiments in storage rings. General formulas describing a behavior of all components of the polarization vector at the magnetic resonance are obtained for an arbitrary initial polarization. These formulas are exact on condition that the nonresonance rotating field is neglected. The spin dynamics is also calculated at frequencies far from resonance with allowance for both rotating fields. A general quantummechanical analysis of the spin evolution at the magnetic resonance is fulfilled and the full agreement between the classical and quantum-mechanical approaches is shown. Quasimagnetic resonances for particles and nuclei moving in noncontinuous perturbing fields of accelerators and storage rings are considered. Distinguishing features of quasimagnetic resonances in storage ring electric-dipole-moment experiments are investigated in detail. The exact formulas for the effect caused by the electric dipole moment are derived. The difference between the resonance effects conditioned by the rf electric-field flipper and the rf Wien filter is found and is calculated for the first time. The existence of this difference is crucial for the establishment of a consent between analytical derivations and computer simulations and for checking spin tracking programs. The main systematical errors are considered.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

General classical and quantum-mechanical description of magnetic resonance: an application to electric-dipole-moment experiments

Silenko

2017

Eur. Phys. J. C

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“…ω a can be reduced to zero (see also [14]). The correct value can be set in the laboratory by monitoring the cancellation of the (g − 2) precession with electron detectors on the inside of the ring.…”

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confidence: 99%

New Method of Measuring Electric Dipole Moments in Storage Rings

et al. 2004

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A new highly sensitive method of looking for electric dipole moments of charged particles in storage rings is described. The major systematic errors inherent in the method are addressed and ways to minimize them are suggested. It seems possible to measure the muon EDM to levels that test speculative theories beyond the standard model. PACS numbers: 13.40. Em, 12.60.Jv, 14.60.Ef, 29.20.Dh The existence of a permanent electric dipole moment (EDM) for an elementary particle would violate parity (P) and time reversal symmetry (T) [1]. Therefore under the assumption of CPT invariance, a non-zero EDM would signal CP violation. In the standard model, the electron EDM is < 10 −38 e · cm [2] with the muon EDM scaled up by the mass ratio m µ /m e , a factor of 207, but some new theories predict much larger values [3,4]. For example, ref.[4] predicts the muon EDM could be as large as 5 × 10 −23 e · cm, while the electron EDM is predicted to be ∼ 10 −28 e · cm, an order of magnitude below the present limit [5]. The current 95% confidence limit for the muon EDM is 10 −18 e·cm [6]. This paper discusses a new way of using a magnetic storage ring to measure the EDM of the muon, which also can be applied to other charged particles.To measure the EDM experimentally, the particle should be in an electric field which exerts a torque on the dipole and induces an observable precession of its spin. If the particle is charged this electric field inevitably accelerates the particle; it will move to a region where the field is zero or leave the scene. An example is the nucleus at the center of an atom in equilibrium; the net force and therefore the net electric field at the nucleus must average to zero according to Schiff's theorem [7]. Any applied external electric field will be shielded from the nucleus by the electrons in the atom. The overall effect is to suppress the EDM signal, making it more difficult to measure. The suppression would be total but for the many known exceptions to Schiff's theorem when weak and strong forces, weak electron-nucleon forces, finite particle sizes, and relativistic effects are included. Suppression of the EDM signal by Schiff's theorem is completely avoided in a magnetic storage ring [8,9] such as proposed here, because the particle is not in equilibrium; there is a net centripetal force, and this force is entirely supplied by a net electric field as seen in the muon rest frame.In particular, when a muon of velocity β = v/c and relativistic mass factor γ = (1 − β 2 ) − 1 2 is circulating in a horizontal plane due to a vertical magnetic field B, it will according to a Lorentz transformation experience both an electric and a magnetic field, E * and B * , in its own rest frame. The so-called motional electric field, E * = γc β × B, can be much larger than any practical applied electric field. Its action on the particle supplies the radial centripetal force, Thomas spin precession, and spin precession due to any non-vanishing EDM. B * produces precession due to the muon magnetic moment. The combined spi...

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“…The spin motion of a particle in the electric and magnetic fields of a machine is governed by the Thomas-BargmannMichel-Telegdi equation [17][18][19], extended to include the EDM [20,21],…”

mentioning

confidence: 99%

New Method for a Continuous Determination of the Spin Tune in Storage Rings and Implications for Precision Experiments

Eversmann¹,

Hejny²,

Hinder³

et al. 2015

Phys. Rev. Lett.

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A new method to determine the spin tune is described and tested. In an ideal planar magnetic ring, the spin tune-defined as the number of spin precessions per turn-is given by ν s ¼ γG (γ is the Lorentz factor, G the gyromagnetic anomaly). At 970 MeV=c, the deuteron spins coherently precess at a frequency of ≈120 kHz in the Cooler Synchrotron COSY. The spin tune is deduced from the up-down asymmetry of deuteron-carbon scattering. In a time interval of 2.6 s, the spin tune was determined with a precision of the PRL 115, 094801 (2015) P H Y S I C A L

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Search for an Electric Dipole Moment of the Electron

Cited by 81 publications

References 6 publications

General classical and quantum-mechanical description of magnetic resonance: an application to electric-dipole-moment experiments

General classical and quantum-mechanical description of magnetic resonance: an application to electric-dipole-moment experiments

New Method of Measuring Electric Dipole Moments in Storage Rings

New Method for a Continuous Determination of the Spin Tune in Storage Rings and Implications for Precision Experiments

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