591 research outputs found
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
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
Investigations of Ra properties to test possibilities of new optical frequency standards
The present work tests the suitability of the narrow transitions $7s \
^2S_{1/2} \to 6d ^2D_{3/2}7s ^2S_{1/2} \to 6d ^2D_{5/2}^+6d^+$ to be considered as a potential
candidate for an atomic clock. This is further corroborated by our studies of
the hyperfine interactions, dipole and quadrupole polarizabilities and
quadrupole moments of the appropriate states of this system.Comment: Latex files, 5 pages, 1 figur
Communication
Visualizing the functional interactions of biomolecules such as proteins and nucleic acids is key to understanding cellular life on the molecular scale. Spatial proximity is often used as a proxy for the direct interaction of biomolecules. However, current techniques to visualize spatial proximity are either limited by spatial resolution, dynamic range, or lack of single-molecule sensitivity. Here, we introduce Proximity-PAINT (pPAINT), a variation of the super-resolution microscopy technique DNA-PAINT. pPAINT uses a split-docking-site configuration to detect spatial proximity with high sensitivity, low false-positive rates, and tunable detection distances. We benchmark and optimize pPAINT using designer DNA nanostructures and demonstrate its cellular applicability by visualizing the spatial proximity of alpha- and beta-tubulin in microtubules using super-resolution detection. © 2020 Wiley-VCH GmbH
Precise Measurement of Magnetic Field Gradients from Free Spin Precession Signals of He and Xe Magnetometers
We report on precise measurements of magnetic field gradients extracted from
transverse relaxation rates of precessing spin samples. The experimental
approach is based on the free precession of gaseous, nuclear spin polarized
He and Xe atoms in a spherical cell inside a magnetic guiding field
of about 400 nT using LT SQUIDs as low-noise magnetic flux detectors. The
transverse relaxation rates of both spin species are simultaneously monitored
as magnetic field gradients are varied. For transverse relaxation times
reaching 100 h, the residual longitudinal field gradient across the spin sample
could be deduced to be pT/cm. The method takes
advantage of the high signal-to-noise ratio with which the decaying spin
precession signal can be monitored that finally leads to the exceptional
accuracy to determine magnetic field gradients at the sub pT/cm scale
Lamb shift in muonic helium ion
The Lamb shift (2P_{1/2}-2S_{1/2}) in the muonic helium ion (mu ^4_2He)^+ is
calculated with the account of contributions of orders alpha^3, alpha^4,
alpha^5 and alpha^6. Special attention is given to corrections of the electron
vacuum polarization, the nuclear structure and recoil effects. The obtained
numerical value of the Lamb shift 1379.028 meV can be considered as a reliable
estimate for the comparison with experimental data.Comment: 18 pages, 11 figure
Aspects of Cooling at the TRIP Facility
The TriP facility at KVI is dedicated to provide short lived radioactive
isotopes at low kinetic energies to users. It comprised different cooling
schemes for a variety of energy ranges, from GeV down to the neV scale. The
isotopes are produced using beam of the AGOR cyclotron at KVI. They are
separated from the primary beam by a magnetic separator. A crucial part of such
a facility is the ability to stop and extract isotopes into a low energy
beamline which guides them to the experiment. In particular we are
investigating stopping in matter and buffer gases. After the extraction the
isotopes can be stored in neutral atoms or ion traps for experiments. Our
research includes precision studies of nuclear -decay through
- momentum correlations as well as searches for permanent electric
dipole moments in heavy atomic systems like radium. Such experiments offer a
large potential for discovering new physics.Comment: COOL05 Workshop, Galena, Il, USA, 18-23. Sept. 2005, 5 pages, 3
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