73 research outputs found
Muonic hydrogen and the proton radius puzzle
The extremely precise extraction of the proton radius by Pohl et al. from the
measured energy difference between the 2P and 2S states of muonic hydrogen
disagrees significantly with that extracted from electronic hydrogen or elastic
electron-proton scattering. This is the proton radius puzzle. The origins of
the puzzle and the reasons for believing it to be very significant are
explained. Various possible solutions of the puzzle are identified, and future
work needed to resolve the puzzle is discussed.Comment: Minor modifications, some references added, to appear in Annu. Rev.
Nucl. Part. Sci. Vol 63 (2013). 60 pages, 5 figures, 1 tabl
Thin-disk laser scaling limit due to thermal-lens induced misalignment instability
We present an obstacle in power scaling of thin-disk lasers related with
self-driven growth of misalignment due to thermal lens effects. This
self-driven growth arises from the changes of the optical phase difference at
the disk caused by the excursion of the laser eigen-mode from the optical axis.
We found a criterion based on a simplified model of this phenomenon which can
be applied to design laser resonators insensitive to this effect. Moreover, we
propose several resonator architectures which are not affected by this effect.Comment: 19 pages, 13 figure
Spatial hole burning in thin-disk lasers and twisted-mode operation
Spatial hole burning prevents single-frequency operation of thin-disk lasers
when the thin disk is used as a folding mirror. We present an evaluation of the
saturation effects in the disk for disks acting as end-mirrors and as
folding-mirrors explaining one of the main obstacles towards single-frequency
operation. It is shown that a twisted-mode scheme based on a multi-order
quarter-wave plate combined with a polarizer provides an almost complete
suppression of spatial hole burning and creates an additional wavelength
selectivity that enforces efficient single-frequency operation.Comment: 14 pages, 16 figure
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
Passive alignment stability and auto-alignment of multipass amplifiers based on Fourier transforms
The stability properties of Fourier-based multipass amplifier to
misalignments (tilts) of its optical components has been investigated. For this
purpose, a method to quantify the sensitivity to tilts based on the amplifier
small signal gain has been elaborated and compared with measurements. To
improve on the tilt stability by more than an order of magnitude a simple
auto-alignment system has been proposed and tested. This study, combined with
other investigations devoted to the stability of the output beam to variations
of aperture and thermal lens effects of the active medium, qualifies the
Fourier-based amplifier for the high-energy and the high-power sector.Comment: 10 pages, 11 figure
Observation of Long-Lived Muonic Hydrogen in the 2S State
The kinetic energy distribution of ground state muonic hydrogen atoms
mu-p(1S) is determined from time-of-flight spectra measured at 4, 16, and 64
hPa H2 room-temperature gas. A 0.9 keV-component is discovered and attributed
to radiationless deexcitation of long-lived mu-p(2S) atoms in collisions with
H2 molecules. The analysis reveals a relative population of about 1%, and a
pressure-dependent lifetime (e.g. (30.4 +21.4 -9.7) ns at 64 hPa) of the
long-lived mu-p(2S) population, equivalent to a 2S-quench rate in mu-p(2S) + H2
collisions of (4.4 +2.1 -1.8) 10^11 s^-1 at liquid hydrogen density.Comment: 4 pages, 2 figures, accepted for publication in Physical Review
Letter
Precision Measurement of the Hydrogen-Deuterium 1S-2S Isotope Shift
Measuring the hydrogen-deuterium isotope shift via two-photon spectroscopy of the 1S-2S transition, we obtain 670994334606(15) Hz. This is a 10-times improvement over the previous best measurement confirming its frequency value. a calculation of the difference of the mean square charge radii of deuterium and hydrogen results in r2d-r2 p=3.82007(65)fm2, a more than twofold improvement compared to the former value
Hydrogen-Deuterium Isotope Shift: From the 1S-2s-Transition Frequency to the Proton-Deuteron Charge-Radius Difference
We analyze and review the theory of the hydrogen-deuterium isotope shift for the 1S-2S transition, which is one of the most accurately measured isotope shifts in any atomic system, in view of a recently improved experiment. A tabulation of all physical effects that contribute to the isotope shift is given. These include the Dirac binding energy, quantum electrodynamic effects, including recoil corrections, and the nuclear-size effect, including the pertaining relativistic and radiative corrections. From a comparison of the theoretical result Δfth=670999566.90(66)(60)kHz (exclusive of the nonrelativistic nuclear-finite-size correction) and the experimental result Δfexpt=670994334605(15) Hz, we infer the deuteron-proton charge-radius difference (r2)d- (r2)p=3.82007(65) fm2 and the deuteron structure radius rstr=1.97507(78) fm
A compact 20-pass thin-disk multipass amplifier stable against thermal lensing effects and delivering 330 mJ pulses with
We report on an Yb:YAG thin-disk multipass amplifier delivering 50 ns long
pulses at a central wavelength of 1030 nm with an energy of 330 mJ at a
repetition rate of 100 Hz. The beam quality factor at the maximum energy was
measured to be . The small signal gain is 20, and the gain
at 330 mJ was measured to be 6.9. The 20-pass amplifier is designed as a
concatenation of stable resonator segments in which the beam is alternately
Fourier transformed and relay-imaged back to the disk by a 4f-imaging optical
scheme stage. The Fourier transform propagation makes the output beam robust
against spherical phase front distortions, while the 4f-stage is used to
compensate the thermal lens of the thin-disk and to reduce the footprint of the
amplifier
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