B. Santra

Atomic parity violation in a single trapped radium ion

Atomic parity violation (APV) experiments are sensitive probes of the electroweak interaction at low energy. These experiments are competitive with and complementary to high-energy collider experiments. The APV signal is strongly enhanced in heavy atoms, and it is measurable by exciting suppressed (M1, E2) transitions. The predicted enhancement factor of the APV effect in the S-D transition in Ra+ is about 50 times larger than the S-S transition in neutral Cs. However, certain spectroscopic information on Ra+, needed to constrain the required atomic many-body theory, was lacking. Using the AGOR cyclotron and the TRIμP facility at KVI in Groningen, short-lived 212–214Ra+ ions were produced and trapped. First ever excited-state laser spectroscopy was performed on the trapped ions. These measurements provide a benchmark for the atomic theory required to extract the electroweak mixing angle to sub 1% accuracy and are an important step towards an APV experiment in a single trapped Ra+ ion. A lower bound on the...

First Test of Lorentz Invariance in the Weak Decay of Polarized Nuclei

A new test of Lorentz invariance in the weak interactions has been made by searching for variations in the decay rate of spin-polarized Na-20 nuclei. This test is unique to Gamow-Teller transitions, as was shown in the framework of a recently developed theory that assumes a Lorentz symmetry breaking background field of tensor nature. The nuclear spins were polarized in the up and down direction, putting a limit on the amplitude of sidereal variations of the form vertical bar(Gamma(up) - Gamma(down))vertical bar/(Gamma(up) + Gamma(down)) <3 x 10(-3). This measurement shows a possible route toward a more detailed testing of Lorentz symmetry in weak interactions.

Light shifts and magic wavelengths for heavy alkaline earth elements: Ba and Ra

In this paper, we investigate light shifts of heavy alkaline earth elements barium (Ba) and radium (Ra), which are interesting for optical lattice clocks and for permanent electric dipole moment searches. Detailed knowledge is required in the design of efficient loading of atoms from a magneto-optical trap into an optical dipole trap, to facilitate Doppler cooling while trapping and to achieve longer lifetimes of the trapped atoms with reduced heating rates. The wavelength dependence of light shifts of the ns(2) (1)S(0) ground state, the nsnp (3)P(1) and ns(n - 1) d (1)D(2) excited states in barium (n = 6) and the n s(2) (1)S(0) ground state, the nsnp (3)P(1) and ns(n - 1) d (3)D(2) excited states in radium (n = 7) are calculated. Several magic wavelengths in the visible and infrared regions accessible with commercial lasers for optical dipole trapping of Ba and Ra are identified.

Isotope shifts of the 6d(2)D(3/2)-7p(2)P(1/2) transition in trapped short-lived Ra-209-214(+)

Laser spectroscopy of short-lived radium isotopes in a linear Paul trap has been performed. The isotope shifts of the 6d(2)D(3/2)-7p(2)P(1/2) transition in Ra-209-214(+), which are sensitive to the short-range part of the atomic wave functions, were measured. The results are essential experimental input for improving the precision of atomic structure calculations. This is indispensable for parity violation in Ra+ aiming at the determination of the weak mixing angle.

Precision spectroscopy of trapped radioactive radium ions

Atomic parity violation (APV) can be measured in a single Ra+ ion, enabling a precise measurement of the electroweak mixing angle in the Standard Model of particle physics at low momentum transfer. This provides sensitivity to new particles such as extra Z0 bosons or leptoquarks. The Weinberg angle can be measured via a determination of the light shift in the forbidden 72S1/2–62D3/2 transition in a single trapped Ra+. Ultra-narrow transitions in such an ideal system can also be exploited to realize a high stability frequency standard. At the TRIμP facility of KVI, we have succeeded in the production of a series of radioactive short-lived radium isotopes. The radium isotopes produced were stopped and thermalized to Ra+ in a thermal ionizer, mass separated in a Wien filter, cooled in a gas filled radio frequency quadrupole and subsequently trapped as a cloud in a linear Paul trap. Laser spectroscopy in the trapped radium ions has been performed. The results of hyperfine structure, isotope shift, and lifetim...

Absolute frequency measurement of the 7s 21 S0-7s7p 1 P1 transition in 225 Ra

Transition frequencies were determined for transitions in Ra in an atomic beam and for reference lines in Te

Absolute frequency measurement of the7s2 1S0–7s7p 1P1transition inRa225

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Absolute frequency measurement of the 7s(2) S-1(0)-7s7 p P-1(1) transition in Ra-225

molecules in a vapor cell. The absolute frequencies were calibrated against a GPS stabilized Rb-clock by means of an optical frequency comb. The 7s

Isotope shifts of the6d2D3/2–7p2P1/2transition in trapped short-lived209−214Ra+

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Isotope Shifts of the

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