55,407 research outputs found
High-temperature thermionic emission microscope
Thermionic emission microscope was designed to operate with metal specimen cathode temperatures of 2000 degrees C
Equivalence of the perturbation theories of Hori and Deprit
Equivalence of perturbation theories of Hori and Deprit, based on Poisson brackets, and computer calculations through sixth orde
Direct frequency comb laser cooling and trapping
Continuous wave (CW) lasers are the enabling technology for producing
ultracold atoms and molecules through laser cooling and trapping. The resulting
pristine samples of slow moving particles are the de facto starting point for
both fundamental and applied science when a highly-controlled quantum system is
required. Laser cooled atoms have recently led to major advances in quantum
information, the search to understand dark energy, quantum chemistry, and
quantum sensors. However, CW laser technology currently limits laser cooling
and trapping to special types of elements that do not include highly abundant
and chemically relevant atoms such as hydrogen, carbon, oxygen, and nitrogen.
Here, we demonstrate that Doppler cooling and trapping by optical frequency
combs may provide a route to trapped, ultracold atoms whose spectra are not
amenable to CW lasers. We laser cool a gas of atoms by driving a two-photon
transition with an optical frequency comb, an efficient process to which every
comb tooth coherently contributes. We extend this technique to create a
magneto-optical trap (MOT), an electromagnetic beaker for accumulating the
laser-cooled atoms for further study. Our results suggest that the efficient
frequency conversion offered by optical frequency combs could provide a key
ingredient for producing trapped, ultracold samples of nature's most abundant
building blocks, as well as antihydrogen. As such, the techniques demonstrated
here may enable advances in fields as disparate as molecular biology and the
search for physics beyond the standard model.Comment: 10 pages, 5 figure
Observing The Hidden Sector
We study the effects of renormalization due to hidden-sector dynamics on
observable soft supersymmetry-breaking parameters in the minimal supersymmetric
extension of the Standard Model (MSSM), under various hypotheses about their
universality at a high input scale. We show that hidden-sector renormalization
effects may induce the spurious appearance of unification of the scalar masses
at some lower scale, as in mirage unification scenarios. We demonstrate in
simple two-parameter models of the hidden-sector dynamics that the parameters
may in principle be extracted from experimental measurements, rendering the
hidden sector observable. We also discuss the ingredients that would be
necessary to carry this programme out in practice.Comment: 38 pages, 13 figures, uses UApreprint.cls and subfigure.sty
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Artificial neural network prediction of weld distortion rectification using a travelling induction coil
An experimental investigation has been carried out to determine the applicability of an induction heating process with a travelling induction coil for the rectification of angular welding distortion. The results obtained from experimentation have been used to create artificial neural network models with the ability to predict the welding induced distortion and the distortion rectification achieved using a travelling induction coil. The experimental results have shown the ability to reduce the angular distortion for 8 mm and 10 mm thick DH36 steel plate and effectively eliminate the distortion on 6 mm thick plate. Results for 6 mm plate also show the existence of a critical induction coil travel speed at which maximum corrective bending occurs. Artificial neural networks have demonstrated the ability to predict the final distortion of the plate after both welding and induction heating. The models have also been used as a tool to determine the optimum speed to minimise the resulting distortion of steel plate after being subjected to both welding and induction heating processes
Activities of the RTG Radiation Test Laboratory Progress report, 1 Jul. - 31 Dec. 1969
Safety, gamma ray spectrum, and data analysis of SNAP fuel capsule
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