248 research outputs found
Theory of the n=2 levels in muonic deuterium
The present knowledge of Lamb shift, fine- and hyperfine structure of the
and states in muonic deuterium is reviewed in
anticipation of the results of a first measurement of several
transition frequencies in muonic deuterium (). A term-by-term
comparison of all available sources reveals reliable values and uncertainties
of the QED and nuclear structure-dependent contributions to the Lamb shift,
which are essential for a determination of the deuteron rms charge radius from
. Apparent discrepancies between different sources are resolved,
in particular for the difficult two-photon exchange contributions. Problematic
single-sourced terms are identified which require independent recalculation.Comment: 26 pages, add missing feynman diagrams (Fig. 3), renumber items (Tab.
IV), correct a sum (column 5, Tab. IV
Rapid Eccentricity Oscillations and the Mergers of Compact Objects in Hierarchical Triples
Kozai-Lidov (KL) oscillations can accelerate compact object mergers via gravitational wave (GW) radiation by driving the inner binaries of hierarchical triples to high eccentricities. We perform direct three-body integrations of high mass ratio compact object triple systems using Fewbody including post-Newtonian terms. We find that the inner binary undergoes rapid eccentricity oscillations (REOs) on the timescale of the outer orbital period which drive it to higher eccentricities than secular theory would otherwise predict, resulting in substantially reduced merger times. For a uniform distribution of tertiary eccentricity (), ~40% of systems merge within ~1-2 eccentric KL timescales whereas secular theory predicts that only ~20% of such systems merge that rapidly. This discrepancy becomes especially pronounced at low , with secular theory overpredicting the merger time by many orders of magnitude. We show that a non-negligible fraction of systems have eccentricity > 0.8 when they merge, in contrast to predictions from secular theory. Our results are applicable to high mass ratio triple systems containing black holes or neutron stars. In objects in which tidal effects are important, such as white dwarfs, stars, and planets, REOs can reduce the tidal circularization timescale by an order of magnitude and bring the components of the inner binary into closer orbits than would be possible in the secular approximation
Compact 20-pass thin-disk amplifier insensitive to thermal lensing
We present a multi-pass amplifier which passively compensates for distortions
of the spherical phase front occurring in the active medium. The design is
based on the Fourier transform propagation which makes the output beam
parameters insensitive to variation of thermal lens effects in the active
medium. The realized system allows for 20 reflections on the active medium and
delivers a small signal gain of 30 with M = 1.16. Its novel geometry
combining Fourier transform propagations with 4f-imaging stages as well as a
compact array of adjustable mirrors allows for a layout with a footprint of 400
mm x 1000 mm.Comment: 7 pages, 6 figure
Muonic hydrogen cascade time and lifetime of the short-lived state
Metastable muonic-hydrogen atoms undergo collisional -quenching,
with rates which depend strongly on whether the kinetic energy is above
or below the energy threshold. Above threshold, collisional
excitation followed by fast radiative
deexcitation is allowed. The corresponding short-lived component
was measured at 0.6 hPa room temperature gas pressure, with
lifetime ns (i.e.,
at liquid-hydrogen density) and population
% (per atom). In
addition, a value of the cascade time, ns, was found.Comment: 4 pages, 3 figure
muCool: A novel low-energy muon beam for future precision experiments
Experiments with muons () and muonium atoms () offer
several promising possibilities for testing fundamental symmetries. Examples of
such experiments include search for muon electric dipole moment, measurement of
muon and experiments with muonium from laser spectroscopy to gravity
experiments. These experiments require high quality muon beams with small
transverse size and high intensity at low energy.
At the Paul Scherrer Institute, Switzerland, we are developing a novel device
that reduces the phase space of a standard beam by a factor of
with efficiency. The phase space compression is achieved by
stopping a standard beam in a cryogenic helium gas. The stopped
are manipulated into a small spot with complex electric and magnetic
fields in combination with gas density gradients. From here, the muons are
extracted into the vacuum and into a field-free region. Various aspects of this
compression scheme have been demonstrated. In this article the current status
will be reported.Comment: 8 pages, 5 figures, TCP 2018 conference proceeding
The Association Between Psychiatric Disorders and Frequent Indoor Tanning
Limited research has explored psychiatric disorders associated with indoor tanning and tanning dependence. In a study conducted in 2006 of students at a large university in the northeastern United States, 90 of 229 (39%) who had used indoor tanning facilities met criteria for tanning dependence,a tanning pattern highly resistant to intervention. Given that tanners report mood and physical appearance as reasons for tanning, psychological disorders, such as seasonal affective disorder (SAD) and body dysmorphic disorder (BDD), may be common among this population. Past research found that 12 of 27 (44%) frequent indoor tanners met criteria for SAD compared with 14 of 56 (25%) nontanners. Other studies have found that stress in general is predictive of tanning dependence,and tanners have been shown to report lower levels of stress after tanning. Ashrafioun and Bonarreported that 57 of 165 (35%) tanners who met criteria for tanning dependence also met criteria for BDD, compared with 77 of 368 (21%) tanners who did not meet these criteria. In the study described here, we assessed the prevalence of SAD, clinically elevated stress, and BDD among a sample of women who frequently use indoor tanning, and we examined bivariate associations between tanning dependence and these psychological conditions
The proton radius puzzle
High-precision measurements of the proton radius from laser spectroscopy of
muonic hydrogen demonstrated up to six standard deviations smaller values than
obtained from electron-proton scattering and hydrogen spectroscopy. The status
of this discrepancy, which is known as the proton radius puzzle will be
discussed in this paper, complemented with the new insights obtained from
spectroscopy of muonic deuterium.Comment: Moriond 2017 conference, 8 pages, 4 figure
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