20 research outputs found
Solid State Systems for Electron Electric Dipole Moment and other Fundamental Measurements
In 1968, F.L. Shapiro published the suggestion that one could search for an
electron EDM by applying a strong electric field to a substance that has an
unpaired electron spin; at low temperature, the EDM interaction would lead to a
net sample magnetization that can be detected with a SQUID magnetometer. One
experimental EDM search based on this technique was published, and for a number
of reasons including high sample conductivity, high operating temperature, and
limited SQUID technology, the result was not particularly sensitive compared to
other experiments in the late 1970's.
Advances in SQUID and conventional magnetometery had led us to reconsider
this type of experiment, which can be extended to searches and tests other than
EDMs (e.g., test of Lorentz invariance). In addition, the complementary
measurement of an EDM-induced sample electric polarization due to application
of a magnetic field to a paramagnetic sample might be effective using modern
ultrasensitive charge measurement techniques. A possible paramagnetic material
is Gd-substituted YIG which has very low conductivity and a net enhancement
(atomic enhancement times crystal screening) of order unity. Use of a
reasonable volume (100's of cc) sample of this material at 50 mK and 10 kV/cm
might yield an electron EDM sensitivity of e cm or better, a factor
of improvement over current experimental limits.Comment: 6 pages. Prepared for ITAMP workshop on fundamental physics that was
to be held Sept 20-22 2001 in Cambride, MA, but was canceled due to terrorist
attack on U.S New version incorporates a number of small changes, most
notably the scaling of the sensitivity of the Faraday magnetometer with
linewidth is now treated in a saner fashion. The possibility of operating at
an even lower temperarture, say 10 microkelvin, is also discusse
Energy levels and lifetimes of Gd IV and enhancement of the electron dipole moment
We have calculated energy levels and lifetimes of 4f7 and 4f6 5d
configurations of Gd IV using Hartree-Fock and configuration interaction
methods. This allows us to reduce significantly the uncertainty of the
theoretical determination of the electron electric dipole moment (EDM)
enhancement factor in this ion and, correspondingly, in gadolinium-containing
garnets for which such measurements were recently proposed. Our new value for
the EDM enhancement factor of Gd+3 is -2.2 +- 0.5. Calculations of energy
levels and lifetimes for Eu~III are used to control the accuracy.Comment: Submitted to Phys. Rev. A 6 pages, 0 figures, 3 table
Searches for violation of fundamental time reversal and space reflection symmetries in solid state experiments
The electric dipole moment (EDM) of a particle violates both time reversal
(T) and space reflection (P) symmetries. There have been recent suggestions for
searches of the electron EDM using solid state experiments [1,2]. These
experiments could improve the sensitivity compared to present atomic and
molecular experiments by several orders of magnitude. In the present paper we
calculate the expected effect. We also suggest that this kind of experiment is
sensitive to T,P-violation in nuclear forces and calculate effects caused by
the nuclear Schiff moment.
The compounds under consideration contain magnetic Gd ions and oxygen
O ions. We demonstrate that the main mechanism for the T,P-odd effects
is related to the penetration of the Oxygen 2p-electrons to the Gd core. All
the effects are related to the deformation of the crystal lattice.Comment: 13 pages, 6 figure
Enhancement of the electron electric dipole moment in gadolinium garnets
Effects caused by the electron electric dipole moment (EDM) in gadolinium
garnets are considered. Experimental studies of these effects could improve
current upper limit on the electron EDM by several orders of magnitude. We
suggest a consistent theoretical model and perform calculations of observable
effects in gadolinium gallium garnet and gadolinium iron garnet. Our
calculation accounts for both direct and exchange diagrams.Comment: 9 page