388,468 research outputs found
Evaporation of buffer gas-thermalized anions out of a multipole rf ion trap
We identify plain evaporation of ions as the fundamental loss mechanism out
of a multipole ion trap. Using thermalized negative Cl- ions we find that the
evaporative loss rate is proportional to a Boltzmann factor. This thermodynamic
description sheds new light on the dynamics of particles in time-varying
confining potentials. It specifically allows us to extract the effective depth
of the ion trap as the activation energy for evaporation. As a function of the
rf amplitude we find two distinct regimes related to the stability of motion of
the trapped ions. For low amplitudes the entire trap allows for stable motion
and the trap depth increases with the rf field. For larger rf amplitudes,
however, rapid energy transfer from the field to the ion motion can occur at
large trap radii, which leads to a reduction of the effective trapping volume.
In this regime the trap depth decreases again with increasing rf amplitude. We
give an analytical parameterization of the trap depth for various multipole
traps that allows predictions of the most favorable trapping conditions.Comment: Phys. Rev. Lett., in pres
Mississippi State Axion Search: A Light Shining though a Wall ALP Search
The elegant solutions to the strong CP problem predict the existence of a
particle called axion. Thus, the search for axion like particles (ALP) has been
an ongoing endeavor. The possibility that these axion like particles couple to
photons in presence of magnetic field gives rise to a technique of detecting
these particles known as light shining through a wall (LSW). Mississippi State
Axion Search (MASS) is an experiment employing the LSW technique in search for
axion like particles. The apparatus consists of two radio frequency (RF)
cavities, both under the influence of strong magnetic field and separated by a
lead wall. While one of the cavities houses a strong RF generator, the other
cavity houses the detector systems. The MASS apparatus looks for excesses in RF
photons that tunnel through the wall as a signature of candidate axion-like
particles. The concept behind the experiment as well as the projected
sensitivities are presented here.Comment: Xth Patras Workshop on Axions, WIMPs and WISPs; 4 Pages, 5 figure
Suppression of inhomogeneous broadening in rf spectroscopy of optically trapped atoms
We present a novel method for reducing the inhomogeneous frequency broadening
in the hyperfine splitting of the ground state of optically trapped atoms. This
reduction is achieved by the addition of a weak light field, spatially
mode-matched with the trapping field and whose frequency is tuned in-between
the two hyperfine levels. We experimentally demonstrate the new scheme with Rb
85 atoms, and report a 50-fold narrowing of the rf spectrum
Liquid Crystal Polarimetry for Metastability Exchange Optical Pumping of 3He
We detail the design and operation of a compact, discharge light polarimeter
for metastability exchange optical pumping of 3He gas near 1 torr under a low
magnetic field. The nuclear polarization of 3He can be discerned from its
electron polarization, measured via the circular polarization of 668 nm
discharge light from an RF excitation. This apparatus measures the circular
polarization of this very dim discharge light using a nematic liquid crystal
wave retarder (LCR) and a high-gain, transimpedance amplified Si photodiode. We
outline corrections required in such a measurement, and discuss contributions
to its systematic error
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