15 research outputs found
An Underappreciated Radiation Hazard from High Voltage Electrodes in Vacuum
The use of high voltage (HV) electrodes in vacuum is commonplace in physics
laboratories. In such systems, it has long been known that electron emission
from an HV cathode can lead to bremsstrahlung X-rays; indeed, this is the basic
principle behind the operation of standard X-ray sources. However, in
laboratory setups where X-ray production is not the goal and no electron source
is deliberately introduced, field-emitted electrons accelerated by HV can
produce X-rays as an unintended hazardous byproduct. Both the level of hazard
and the safe operating regimes for HV vacuum electrode systems are not widely
appreciated, at least in university laboratories. A reinforced awareness of the
radiation hazards associated with vacuum HV setups would be beneficial. We
present a case study of a HV vacuum electrode device operated in a university
atomic physics laboratory. We describe the characterisation of the observed
X-ray radiation, its relation to the observed leakage current in the device,
the steps taken to contain and mitigate the radiation hazard, and suggest
safety guidelines.Comment: Submitted to Health Physic
Branching Ratios, Radiative Lifetimes and Transition Dipole Moments for YbOH
Medium resolution (Δν~ 3 GHz) laser-induced fluorescence (LIF) excitation spectra of a rotationally cold sample of YbOH in the 17300-17950 cm⁻¹ range have been recorded using two-dimensional (excitation and dispersed fluorescence) spectroscopy. High resolution (Δλ~ 0.65 nm) dispersed laser induced fluorescence (DLIF) spectra and radiative decay curves of numerous bands detected in the medium resolution LIF excitation spectra were recorded. The vibronic energy levels of the X²Σ state were predicted using a discrete variable representation approach and compared with observations. The radiative decay curves were analyzed to produce fluorescence lifetimes. DLIF spectra resulting from high resolution (Δν < 10 MHz) LIF excitation of individual low-rotational lines in the A²Π_(1/2)(000)-X²Σ((000), A²Π_(1/2)(100)-X²Σ((000), and [17.73]Ω=0.5-X²Σ((000) bands were also recorded. The DLIF spectra were analyzed to determine branching ratios which were combined with radiative lifetimes to obtain transition dipole moments. The implications for laser cooling and trapping of YbOH are discussed
Vibronic branching ratios for nearly-closed rapid photon cycling of SrOH
The vibrational branching ratios of SrOH for radiative decay to the ground
electronic state, , from the first two electronically excited
states, and , are determined experimentally at the
level. The observed small branching ratios enable the design of a
full, practical laser-cooling scheme, including magneto-optical trapping and
sub-Doppler laser cooling, with photon scatters per molecule. Ab initio
calculations sensitive to weak vibronic transitions are performed to facilitate
the experimental measurement and analysis, and show good agreement with
experiment.Comment: 6 pages, 3 figures, 3 table