1,142 research outputs found
Absolute frequency measurement of the 7s S 7s7p P transition in Ra
Transition frequencies were determined for transitions in Ra in an atomic
beam and for reference lines in Te 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^2\,^1S(F = 1/2)-7s7p\,^1P(F = 3/2)
transition in Ra was determined to be MHz. The
measurements provide input for designing efficient and robust laser cooling of
Ra atoms in preparation of a search for a permanent electric dipole moment in
Ra isotopes.Comment: Accepted for publication in the rapid communication of Physical
review
Calculations of energy levels and lifetimes of low-lying states of barium and radium
We use the configuration interaction method and many-body perturbation theory
to perform accurate calculations of energy levels, transition amplitudes, and
lifetimes of low-lying states of barium and radium. Calculations for radium are
needed for the planning of measurements of parity and time invariance violating
effects which are strongly enhanced in this atom. Calculations for barium are
used to control the accuracy of the calculations.Comment: 8 page
Determination of transition frequencies in a single Ba ion
Transition frequencies between low-lying energy levels in a single trapped
Ba ion have been measured with laser spectroscopy referenced to
an optical frequency comb. By extracting the frequencies of one-photon and
two-photon components of the line shape using an eight-level optical Bloch
model, we achieved 0.1 MHz accuracy for the 5d D - 6p
P and 6s S - 5d D transition
frequencies, and 0.2 MHz for the 6s S - 6p P
transition frequency.Comment: 5 pages, 7 figures, submitted to Phys. Rev.
Dual Magnetic Separator for TRIP
The TRIP facility, under construction at KVI, requires the production
and separation of short-lived and rare isotopes. Direct reactions,
fragmentation and fusion-evaporation reactions in normal and inverse kinematics
are foreseen to produce nuclides of interest with a variety of heavy-ion beams
from the superconducting cyclotron AGOR. For this purpose, we have designed,
constructed and commissioned a versatile magnetic separator that allows
efficient injection into an ion catcher, i.e., gas-filled stopper/cooler or
thermal ionizer, from which a low energy radioactive beam will be extracted.
The separator performance was tested with the production and clean separation
of Na ions, where a beam purity of 99.5% could be achieved. For
fusion-evaporation products, some of the features of its operation as a
gas-filled recoil separator were tested.Comment: accepted by Nucl.Instr. Meth., final versio
Super-resolution imaging and estimation of protein copy numbers at single synapses with DNA-PAINT
In the brain, the strength of each individual synapse is defined by the complement of proteins present or the "local proteome." Activity-dependent changes in synaptic strength are the result of changes in this local proteome and posttranslational protein modifications. Although most synaptic proteins have been identified, we still know little about protein copy numbers in individual synapses and variations between synapses. We use DNA-point accumulation for imaging in nanoscale topography as a single-molecule super-resolution imaging technique to visualize and quantify protein copy numbers in single synapses. The imaging technique provides near-molecular spatial resolution, is unaffected by photobleaching, enables imaging of large field of views, and provides quantitative molecular information. We demonstrate these benefits by accessing copy numbers of surface AMPA-type receptors at single synapses of rat hippocampal neurons along dendritic segments
Production of Radioactive Nuclides in Inverse Reaction Kinematics
Efficient production of short-lived radioactive isotopes in inverse reaction
kinematics is an important technique for various applications. It is
particularly interesting when the isotope of interest is only a few nucleons
away from a stable isotope. In this article production via charge exchange and
stripping reactions in combination with a magnetic separator is explored. The
relation between the separator transmission efficiency, the production yield,
and the choice of beam energy is discussed. The results of some exploratory
experiments will be presented.Comment: 10 pages, 4 figures, to be submitted to Nucl. Instr. and Met
nanoTRON: a Picasso module for MLP-based classification of super-resolution data
Motivation: Classification of images is an essential task in higher-level analysis of biological data. By bypassing the diffraction limit of light, super-resolution microscopy opened up a new way to look at molecular details using light microscopy, producing large amounts of data with exquisite spatial detail. Statistical exploration of data usually needs initial classification, which is up to now often performed manually. Results: We introduce nanoTRON, an interactive open-source tool, which allows super-resolution data classification based on image recognition. It extends the software package Picasso with the first deep learning tool with a graphic user interface
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