19 research outputs found
Measurement of the 6s - 7p transition probabilities in atomic cesium and a revised value for the weak charge Q_W
We have measured the 6s - 7p_{1/2,3/2} transition probabilities in atomic
cesium using a direct absorption technique. We use our result plus other
previously measured transition rates to derive an accurate value of the vector
transition polarizability \beta and, consequently, re-evaluate the weak charge
Q_W. Our derived value Q_W=-72.65(49) agrees with the prediction of the
standard model to within one standard deviation.Comment: 4 pages, 2 figure
Positive column contraction of the glow discharge in nitrogen
This paper studies the diffuse mode of the positive column in nitrogen, the contracted one near the threshold of its onset as well as the transition between these modes. The dynamics of the reduced electric field E/p variation as well as that of the electron temperature Te and the plasma concentration are investigated with a Langmuir probe in the process of this transition. The diffuse mode is observed at low pressure in the total range of discharge current values as well as at the pressure values above the threshold one of 1.5 Torr and low current values. The contracted mode sets on at the pressure values above 1.5 Torr. A jump-like transition occurs between the diffuse mode (with low E/p and Te) and the contracted one when a critical current value is attained.ΠΡΡΠ»Π΅Π΄ΠΎΠ²Π°Π½ ΠΏΠΎΠ»ΠΎΠΆΠΈΡΠ΅Π»ΡΠ½ΡΠΉ ΡΡΠΎΠ»Π± Π² Π°Π·ΠΎΡΠ΅ Π² ΠΎΠ΄Π½ΠΎΡΠΎΠ΄Π½ΠΎΠΌ ΡΠ΅ΠΆΠΈΠΌΠ΅, Π² ΠΊΠΎΠ½ΡΡΠ°Π³ΠΈΡΠΎΠ²Π°Π½Π½ΠΎΠΌ ΡΠ΅ΠΆΠΈΠΌΠ΅ Π²Π±Π»ΠΈΠ·ΠΈ ΠΏΠΎΡΠΎΠ³Π° Π΅Π³ΠΎ ΠΏΠΎΡΠ²Π»Π΅Π½ΠΈΡ, Π° ΡΠ°ΠΊΠΆΠ΅ ΠΏΠ΅ΡΠ΅Ρ
ΠΎΠ΄ ΠΌΠ΅ΠΆΠ΄Ρ ΡΡΠΈΠΌΠΈ ΡΠ΅ΠΆΠΈΠΌΠ°ΠΌΠΈ. Π‘ ΠΏΠΎΠΌΠΎΡΡΡ ΠΠ΅Π½Π³ΠΌΡΡΠΎΠ²ΡΠΊΠΎΠ³ΠΎ Π·ΠΎΠ½Π΄Π° ΠΈΠ·ΡΡΠ΅Π½Π° Π΄ΠΈΠ½Π°ΠΌΠΈΠΊΠ° ΠΈΠ·ΠΌΠ΅Π½Π΅Π½ΠΈΡ ΠΏΡΠΈΠ²Π΅Π΄Π΅Π½Π½ΠΎΠ³ΠΎ ΡΠ»Π΅ΠΊΡΡΠΈΡΠ΅ΡΠΊΠΎΠ³ΠΎ ΠΏΠΎΠ»Ρ E/p, ΡΠ΅ΠΌΠΏΠ΅ΡΠ°ΡΡΡΡ ΡΠ»Π΅ΠΊΡΡΠΎΠ½ΠΎΠ² Te ΠΈ ΠΏΠ»ΠΎΡΠ½ΠΎΡΡΠΈ ΠΏΠ»Π°Π·ΠΌΡ Π² ΠΏΡΠΎΡΠ΅ΡΡΠ΅ Π΄Π°Π½Π½ΠΎΠ³ΠΎ ΠΏΠ΅ΡΠ΅Ρ
ΠΎΠ΄Π°. ΠΠΈΡΡΡΠ·Π½ΡΠΉ ΡΠ΅ΠΆΠΈΠΌ Π½Π°Π±Π»ΡΠ΄Π°Π΅ΡΡΡ ΠΏΡΠΈ Π½ΠΈΠ·ΠΊΠΈΡ
Π΄Π°Π²Π»Π΅Π½ΠΈΡΡ
Π²ΠΎ Π²ΡΡΠΌ Π΄ΠΈΠ°ΠΏΠ°Π·ΠΎΠ½Π΅ ΡΠ°Π·ΡΡΠ΄Π½ΡΡ
ΡΠΎΠΊΠΎΠ², Π° ΡΠ°ΠΊΠΆΠ΅ ΠΏΡΠΈ Π΄Π°Π²Π»Π΅Π½ΠΈΡΡ
Π²ΡΡΠ΅ ΠΏΠΎΡΠΎΠ³ΠΎΠ²ΠΎΠ³ΠΎ 1,5 ToΡΡ ΠΈ Π½ΠΈΠ·ΠΊΠΈΡ
ΡΠΎΠΊΠ°Ρ
. ΠΠΎΠ½ΡΡΠ°Π³ΠΈΡΠΎΠ²Π°Π½Π½ΡΠΉ ΡΠ΅ΠΆΠΈΠΌ ΠΏΠΎΡΠ²Π»ΡΠ΅ΡΡΡ ΠΏΡΠΈ Π΄Π°Π²Π»Π΅Π½ΠΈΡΡ
Π²ΡΡΠ΅ 1,5 ToΡΡ. ΠΠ΅ΠΆΠ΄Ρ Π΄ΠΈΡΡΡΠ·Π½ΡΠΌ ΡΠ΅ΠΆΠΈΠΌΠΎΠΌ (Ρ Π½ΠΈΠ·ΠΊΠΈΠΌΠΈ E/p ΠΈ Te) ΠΈ ΠΊΠΎΠ½ΡΡΠ°Π³ΠΈΡΠΎΠ²Π°Π½Π½ΡΠΌ (Ρ Π²ΡΡΠΎΠΊΠΈΠΌΠΈ E/p ΠΈ Te) ΠΏΡΠΈ Π΄ΠΎΡΡΠΈΠΆΠ΅Π½ΠΈΠΈ ΠΊΡΠΈΡΠΈΡΠ΅ΡΠΊΠΎΠ³ΠΎ ΡΠΎΠΊΠ° ΠΏΡΠΎΠΈΡΡ
ΠΎΠ΄ΠΈΡ ΡΠΊΠ°ΡΠΊΠΎΠΎΠ±ΡΠ°Π·Π½ΡΠΉ ΠΏΠ΅ΡΠ΅Ρ
ΠΎΠ΄.ΠΠΎΡΠ»ΡΠ΄ΠΆΠ΅Π½ΠΎ ΠΏΠΎΠ·ΠΈΡΠΈΠ²Π½ΠΈΠΉ ΡΡΠΎΠ²ΠΏ Π² Π°Π·ΠΎΡΡ Π² ΠΎΠ΄Π½ΠΎΡΡΠ΄Π½ΠΎΠΌΡ ΡΠ΅ΠΆΠΈΠΌΡ, Π² ΠΊΠΎΠ½ΡΡΠ°Π³ΠΎΠ²Π°Π½ΠΎΠΌΡ ΡΠ΅ΠΆΠΈΠΌΡ ΠΏΠΎΠ±Π»ΠΈΠ·Ρ ΠΏΠΎΡΠΎΠ³Π° ΠΉΠΎΠ³ΠΎ Π²ΠΈΠ½ΠΈΠΊΠ½Π΅Π½Π½Ρ, Π° ΡΠ°ΠΊΠΎΠΆ ΠΏΠ΅ΡΠ΅Ρ
ΡΠ΄ ΠΌΡΠΆ ΡΠΈΠΌΠΈ ΡΠ΅ΠΆΠΈΠΌΠ°ΠΌΠΈ. ΠΠ° Π΄ΠΎΠΏΠΎΠΌΠΎΠ³ΠΎΡ ΠΠ΅Π½Π³ΠΌΡΡΡΠ²ΡΡΠΊΠΎΠ³ΠΎ Π·ΠΎΠ½Π΄Π° Π²ΠΈΠ²ΡΠ΅Π½Π° Π΄ΠΈΠ½Π°ΠΌΡΠΊΠ° Π·ΠΌΡΠ½ΠΈ Π·Π²Π΅Π΄Π΅Π½ΠΎΠ³ΠΎ Π΅Π»Π΅ΠΊΡΡΠΈΡΠ½ΠΎΠ³ΠΎ ΠΏΠΎΠ»Ρ E/p, ΡΠ΅ΠΌΠΏΠ΅ΡΠ°ΡΡΡΠΈ Π΅Π»Π΅ΠΊΡΡΠΎΠ½ΡΠ² Te Ρ Π³ΡΡΡΠΈΠ½ΠΈ ΠΏΠ»Π°Π·ΠΌΠΈ Π² ΠΏΡΠΎΡΠ΅ΡΡ ΡΡΠΎΠ³ΠΎ ΠΏΠ΅ΡΠ΅Ρ
ΠΎΠ΄Ρ. ΠΠΈΡΡΠ·Π½ΠΈΠΉ (ΠΎΠ΄Π½ΠΎΡΡΠ΄Π½ΠΈΠΉ) ΡΠ΅ΠΆΠΈΠΌ ΡΠΏΠΎΡΡΠ΅ΡΡΠ³Π°ΡΡΡΡΡ ΠΏΡΠΈ Π½ΠΈΠ·ΡΠΊΠΎΠΌΡ ΡΠΈΡΠΊΡ Ρ Π²ΡΡΠΎΠΌΡ Π΄ΡΠ°ΠΏΠ°Π·ΠΎΠ½Ρ ΡΠΎΠ·ΡΡΠ΄Π½ΠΎΠ³ΠΎ ΡΡΡΡΠΌΡ, Π° ΡΠ°ΠΊΠΎΠΆ ΠΏΡΠΈ ΡΠΈΡΠΊΡ Π²ΠΈΡΠ΅ ΠΏΠΎΡΠΎΠ³ΠΎΠ²ΠΎΠ³ΠΎ 1,5 ToΡΡ Ρ Π½ΠΈΠ·ΡΠΊΠΎΠΌΡ ΡΡΡΡΠΌΡ. ΠΠΎΠ½ΡΡΠ°Π³ΠΎΠ²Π°Π½ΠΈΠΉ ΡΠ΅ΠΆΠΈΠΌ Π·'ΡΠ²Π»ΡΡΡΡΡΡ ΠΏΡΠΈ ΡΠΈΡΠΊΡ Π²ΠΈΡΠ΅ 1,5 ToΡΡ. ΠΡΠΆ Π΄ΠΈΡΡΠ·Π½ΠΈΠΌ ΡΠ΅ΠΆΠΈΠΌΠΎΠΌ (Π· Π½ΠΈΠ·ΡΠΊΠΈΠΌΠΈ E/p Ρ Te) Ρ ΠΊΠΎΠ½ΡΡΠ°Π³ΠΎΠ²Π°Π½ΠΈΠΌ (Π· Π²ΠΈΡΠΎΠΊΠΈΠΌΠΈ E/p Ρ Te) ΠΏΡΠΈ Π΄ΠΎΡΡΠ³Π½Π΅Π½Π½Ρ ΠΊΡΠΈΡΠΈΡΠ½ΠΎΠ³ΠΎ ΡΡΡΡΠΌΡ Π²ΡΠ΄Π±ΡΠ²Π°ΡΡΡΡΡ ΡΡΡΠΈΠ±ΠΊΠΎΠΏΠΎΠ΄ΡΠ±Π½ΠΈΠΉ ΠΏΠ΅ΡΠ΅Ρ
ΡΠ΄
Reevaluation of the role of nuclear uncertainties in experiments on atomic parity violation with isotopic chains
In light of new data on neutron distributions from experiments with
antiprotonic atoms [ Trzcinska {\it et al.}, Phys. Rev. Lett. 87, 082501
(2001)], we reexamine the role of nuclear-structure uncertainties in the
interpretation of measurements of parity violation in atoms using chains of
isotopes of the same element. With these new nuclear data, we find an
improvement in the sensitivity of isotopic chain measurements to ``new
physics'' beyond the standard model. We compare possible constraints on ``new
physics'' with the most accurate to date single-isotope probe of parity
violation in the Cs atom. We conclude that presently isotopic chain experiments
employing atoms with nuclear charges Z < 50 may result in more accurate tests
of the weak interaction.Comment: 6 pages, 1 fig., submitted to Phys. Rev.
High-precision determination of transition amplitudes of principal transitions in Cs from van der Waals coefficient C_6
A method for determination of atomic dipole matrix elements of principal
transitions from the value of dispersion coefficient C_6 of molecular
potentials correlating to two ground-state atoms is proposed. The method is
illustrated on atomic Cs using C_6 deduced from high-resolution Feshbach
spectroscopy. The following reduced matrix elements are determined < 6S_{1/2}
|| D || 6P_{1/2} > =4.5028(60) |e| a0 and
=6.3373(84) |e| a0 (a0= 0.529177 \times 10^{-8} cm.) These matrix elements are
consistent with the results of the most accurate direct lifetime measurements
and have a similar uncertainty. It is argued that the uncertainty can be
considerably reduced as the coefficient C_6 is constrained further.Comment: 4 pages; 3 fig
Off-Diagonal Hyperfine Interaction and Parity Non-conservation in Cesium
We have performed relativistic many-body calculations of the hyperfine
interaction in the and states of Cs, including the off-diagonal
matrix element. The calculations were used to determine the accuracy of the
semi-empirical formula for the electromagnetic transition amplitude
induced by the hyperfine interaction. We have found that even
though the contribution of the many-body effects into the matrix elements is
very large, the square root formula remains valid to the accuracy of a fraction of .
The result for the M1-amplitude is used in the interpretation of the
parity-violation measurement in the transition in Cs which claims a
possible deviation from the Standard model.Comment: 13 pages, 4 figures, LaTeX, Submitted to Phys. Rev.
Precise calculation of parity nonconservation in cesium and test of the standard model
We have calculated the 6s-7s parity nonconserving (PNC) E1 transition
amplitude, E_{PNC}, in cesium. We have used an improved all-order technique in
the calculation of the correlations and have included all significant
contributions to E_{PNC}. Our final value E_{PNC} = 0.904 (1 +/- 0.5 %) \times
10^{-11}iea_{B}(-Q_{W}/N) has half the uncertainty claimed in old calculations
used for the interpretation of Cs PNC experiments. The resulting nuclear weak
charge Q_{W} for Cs deviates by about 2 standard deviations from the value
predicted by the standard model.Comment: 24 pages, 8 figure
Parity nonconservation in heavy atoms: The radiative correction enhanced by the strong electric field of the nucleus
Parity nonconservation due to the nuclear weak charge is considered. We
demonstrate that the radiative corrections to this effect due to the vacuum
fluctuations of the characteristic size larger than the nuclear radius
and smaller than the electron Compton wave-length are enhanced
because of the strong electric field of the nucleus. The parameter that allows
one to classify the corrections is the large logarithm .
The vacuum polarization contribution is enhanced by the second power of the
logarithm. Although the self-energy and the vertex corrections do not vanish,
they contain only the first power of the logarithm. The value of the radiative
correction is 0.4% for Cs and 0.9% for Tl, Pb, and Bi. We discuss also how the
correction affects the interpretation of the experimental data on parity
nonconservation in atoms.Comment: 4 pages, 3 figures, RevTe
Accurate spline solutions of the Dirac equation with parity-nonconserving potential
The complete system of the B-spline solutions for the Dirac equation with the
parity-nonconserving (PNC) weak interaction effective potential is obtained.
This system can be used for the accurate evaluation of the radiative
corrections to the PNC amplitudes in the multicharged ions and neutral atoms.
The use of the scaling procedure allows for the evaluation of the PNC matrix
elements with relative accuracy .Comment: 7 page
Possibility of an ultra-precise optical clock using the transition in Yb atoms held in an optical lattice
We report calculations designed to assess the ultimate precision of an atomic
clock based on the 578 nm transition in Yb atoms
confined in an optical lattice trap. We find that this transition has a natural
linewidth less than 10 mHz in the odd Yb isotopes, caused by hyperfine
coupling. The shift in this transition due to the trapping light acting through
the lowest order AC polarizability is found to become zero at the magic trap
wavelength of about 752 nm. The effects of Rayleigh scattering, higher-order
polarizabilities, vector polarizability, and hyperfine induced electronic
magnetic moments can all be held below a mHz (about a part in 10^{18}), except
in the case of the hyperpolarizability larger shifts due to nearly resonant
terms cannot be ruled out without an accurate measurement of the magic
wavelength.Comment: 4 pages, 1 figur
Calculations of parity nonconserving s-d transitions in Cs, Fr, Ba II, and Ra II
We have performed ab initio mixed-states and sum-over-states calculations of
parity nonconserving (PNC) electric dipole (E1) transition amplitudes between
s-d electron states of Cs, Fr, Ba II, and Ra II. For the lower states of these
atoms we have also calculated energies, E1 transition amplitudes, and
lifetimes. We have shown that PNC E1 transition amplitudes between s-d states
can be calculated to high accuracy. Contrary to the Cs 6s-7s transition, in
these transitions there are no strong cancelations between different terms in
the sum-over-states approach. In fact, there is one dominating term which
deviates from the sum by less than 20%. This term corresponds to an s-p_{1/2}
weak matrix element, which can be calculated to better than 1%, and a
p_{1/2}-d_{3/2} E1 transition amplitude, which can be measured. Also, the s-d
amplitudes are about four times larger than the corresponding s-s transitions.
We have shown that by using a hybrid mixed-states/sum-over-states approach the
accuracy of the calculations of PNC s-d amplitudes could compete with that of
Cs 6s-7s if p_{1/2}-d_{3/2} E1 amplitudes are measured to high accuracy.Comment: 15 pages, 8 figures, submitted to Phys. Rev.