2,331 research outputs found
The effects of the pre-pulse on capillary discharge extreme ultraviolet laser
In the past few years collisionally pumped extreme ultraviolet (XUV) lasers
utilizing a capillary discharge were demonstrated. An intense current pulse is
applied to a gas filled capillary, inducing magnetic collapse (Z-pinch) and
formation of a highly ionized plasma column. Usually, a small current pulse
(pre-pulse) is applied to the gas in order to pre-ionize it prior to the onset
of the main current pulse. In this paper we investigate the effects of the
pre-pulse on a capillary discharge Ne-like Ar XUV laser (46.9nm). The
importance of the pre-pulse in achieving suitable initial conditions of the gas
column and preventing instabilities during the collapse is demonstrated.
Furthermore, measurements of the amplified spontaneous emission (ASE)
properties (intensity, duration) in different pre-pulse currents revealed
unexpected sensitivity. Increasing the pre-pulse current by a factor of two
caused the ASE intensity to decrease by an order of magnitude - and to nearly
disappear. This effect is accompanied by a slight increase in the lasing
duration. We attribute this effect to axial flow in the gas during the
pre-pulse.Comment: 4 pages, 4 figure
Isotropic magnetometry with simultaneous excitation of orientation and alignment CPT resonances
Atomic magnetometers have very high absolute precision and sensitivity to
magnetic fields but suffer from a fundamental problem: the vectorial or
tensorial interaction of light with atoms leads to "dead zones", certain
orientations of magnetic field where the magnetometer loses its sensitivity. We
demonstrate a simple polarization modulation scheme that simultaneously creates
coherent population trapping (CPT) in orientation and alignment, thereby
eliminating dead zones. Using Rb in a 10 Torr buffer gas cell we measure
narrow, high-contrast CPT transparency peaks in all orientations and also show
absence of systematic effects associated with non-linear Zeeman splitting.Comment: 4 pages, 4 figure
Neutrino physics with multi-ton scale liquid xenon detectors
We study the sensitivity of large-scale xenon detectors to low-energy solar
neutrinos, to coherent neutrino-nucleus scattering and to neutrinoless double
beta decay. As a concrete example, we consider the xenon part of the proposed
DARWIN (Dark Matter WIMP Search with Noble Liquids) experiment. We perform
detailed Monte Carlo simulations of the expected backgrounds, considering
realistic energy resolutions and thresholds in the detector. In a low-energy
window of 2-30 keV, where the sensitivity to solar pp and Be-neutrinos is
highest, an integrated pp-neutrino rate of 5900 events can be reached in a
fiducial mass of 14 tons of natural xenon, after 5 years of data. The
pp-neutrino flux could thus be measured with a statistical uncertainty around
1%, reaching the precision of solar model predictions. These low-energy solar
neutrinos will be the limiting background to the dark matter search channel for
WIMP-nucleon cross sections below 210 cm and WIMP
masses around 50 GeVc, for an assumed 99.5% rejection of
electronic recoils due to elastic neutrino-electron scatters. Nuclear recoils
from coherent scattering of solar neutrinos will limit the sensitivity to WIMP
masses below 6 GeVc to cross sections above
410cm. DARWIN could reach a competitive half-life
sensitivity of 5.610 y to the neutrinoless double beta decay of
Xe after 5 years of data, using 6 tons of natural xenon in the central
detector region.Comment: 17 pages, 4 figure
- …