15,840 research outputs found
Commissioning of the 1.4 Mev/u High Current Heavy Ion Linac at Gsi
The disassembly of the Unilac prestripper linac of the Wideroe type took
place at the beginning of 1999. An increase of more than two orders of
magnitude in particle number for the most heavy elements in the SIS had to be
gained. Since that time the new High Current Injector (HSI) consisting of
H-type RFQ and DTL-structures for dual beam operation was installed and
successfully commissioned. The High Charge Injector (HLI) supplied the main
linac during that time. Simultaneously conditioning and running in of the
rf-transmitters and rf-structures were done. The HSI commissioning strategy
included beam investigation after each transport and acceleration section,
using a versatile diagnostic test stand. Results of the extensive commissioning
measurements (e.g. transverse emittance, bunch width, beam transmission) behind
LEBT, RFQ, Super Lens, IH tank I and II and stripping section will be
discussed. An 40Ar1+ beam coming from a MUCIS ion source was used to fill the
linac up to the theoretical space charge limit. Routine operation started in
November 1999.Comment: Linac 2000, FR201, 5 pages, 8 figure
Stellar Velocity Dispersion and Black Hole Mass in the Blazar Markarian 501
The recently discovered correlation between black hole mass and stellar
velocity dispersion provides a new method to determine the masses of black
holes in active galaxies. We have obtained optical spectra of Markarian 501, a
nearby gamma-ray blazar with emission extending to TeV energies. The stellar
velocity dispersion of the host galaxy, measured from the calcium triplet lines
in a 2"x3.7" aperture, is 372 +/- 18 km/s. If Mrk 501 follows the M-sigma
correlation defined for local galaxies, then its central black hole has a mass
of (0.9-3.4)x10^9 solar masses. This is significantly larger than some previous
estimates for the central mass in Mrk 501 that have been based on models for
its nonthermal emission. The host galaxy luminosity implies a black hole of
6x10^8 solar masses, but this is not in severe conflict with the mass derived
from the M-sigma relation because the M_BH-L_bulge correlation has a large
intrinsic scatter. Using the emission-line luminosity to estimate the
bolometric luminosity of the central engine, we find that Mrk 501 radiates at
an extremely sub-Eddington level of L/L_Edd ~ 10^-4. Further applications of
the M-sigma relation to radio-loud active galactic nuclei may be useful for
interpreting unified models and understanding the relationship between radio
galaxies and BL Lac objects.Comment: To appear in ApJ Letters. 5 pages, 2 figure
Investigation of a lineament expressed in an oblique Apollo 9 photograph
The author has identified the following significant results. A linear topographic feature, referred to as the New York Mountains lineament, was recognized in an oblique Apollo 9 photograph to extend from the Providence Mountains of California to near Lake Mead, Arizona. In subsequent vertical ERTS-1 imagery this feature was found to have vague and indistinct expression. A study was conducted to determine the possible geologic origin(s) of the lineament and to explain its anomalous expression in the Apollo 9 photograph. The results suggest that the apparent expression of the lineament is due to a combination of the oblique view of the Apollo photograph, low sun angle illumination of southeast facing slopes, shadowing of northwest facing slopes, and linear snow line along the southeastern flank of the New York Mountains. No geologic or structural causes for the lineament have been found
A simple remark on a flat projective morphism with a Calabi-Yau fiber
If a K3 surface is a fiber of a flat projective morphisms over a connected
noetherian scheme over the complex number field, then any smooth connected
fiber is also a K3 surface. Observing this, Professor Nam-Hoon Lee asked if the
same is true for higher dimensional Calabi-Yau fibers. We shall give an
explicit negative answer to his question as well as a proof of his initial
observation.Comment: 8 pages, main theorem is generalized, one more remark is added,
mis-calculation and typos are corrected etc
The Third Way: Prevention and Compensation of Work Injury in Victoria, Australia
This study originated because the leadership of the VWA and the responsible Minister wanted an assessment of the performance of the Victorian scheme within a larger perspective. They commissioned the W. E. Upjohn Institute for Employment Research, an endowed, not-forprofit research foundation in the United States, to assemble an appropriate team of workers' compensation experts to conduct such a study. The assignment was to carry out a thorough, independent review of the Victorian system of prevention and compensation for work injuries and to provide a set of informed judgments about the system and its performance
Fabrication and characterization of high quality factor silicon nitride nanobeam cavities
Si3N4 is an excellent material for applications of nanophotonics at visible
wavelengths due to its wide bandgap and moderately large refractive index (n
2.0). We present the fabrication and characterization of Si3N4
photonic crystal nanobeam cavities for coupling to diamond nanocrystals and
Nitrogen-Vacancy centers in a cavity QED system. Confocal
micro-photoluminescence analysis of the nanobeam cavities demonstrates quality
factors up to Q ~ 55,000, which is limited by the resolution of our
spectrometer. We also demonstrate coarse tuning of cavity resonances across the
600-700nm range by lithographically scaling the size of fabricated devices.
This is an order of magnitude improvement over previous SiNx cavities at this
important wavelength range
Theoretical and experimental investigations of the drag of installed aircraft radiators
The present report proposes the determination of the absolute magnitude of the total radiator drag and, in addition, of the different causes of the radiator drag
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