37,085 research outputs found
Radiation noise in a high sensitivity star sensor
An extremely accurate attitude determination was developed for space applications. This system uses a high sensitivity star sensor in which the photomultiplier tube is subject to noise generated by space radiations. The space radiation induced noise arises from trapped electrons, solar protons and other ionizing radiations, as well as from dim star background. The solar activity and hence the electron and proton environments are predicted through the end of the twentieth century. The available data for the response of the phototube to proton, electron, gamma ray, and bremsstrahlung radiations are reviewed and new experimental data is presented. A simulation was developed which represents the characteristics of the effect of radiations on the star sensor, including the non-stationarity of the backgrounds
Prompt Photon plus Charm Production at Next-to-Leading Order in QCD
The two particle inclusive cross section for the reaction is studied in perturbative quantum
chromodynamics at order . Differential distributions are
provided for various observables, and a comparison is made with data from the
CDF collaboration.Comment: 4 pages, LaTeX, uses stwol.sty, 6 postscript figures. Invited paper
presented by E. L. Berger at the 28th International Conference on High Energy
Physics, Warsaw, Poland, July 25 - 31, 199
Associated Production of Charm and a Hard Photon
The two particle inclusive cross section for the reaction is studied in perturbative quantum
chromodynamics at order , for large values of the transverse
momentum of the prompt photon and charm quark. Two different techniques are
used in performing the phase-space integrals; the first is purely analytical,
and the second is a combination of analytic and Monte Carlo integration
methods. The second, more versatile technique facilitates imposition of photon
isolation restrictions and other selections of relevance in experiments.
Differential distributions are provided for various observables, and a
comparison is made with preliminary data from the CDF collaboration.Comment: 6 pages. Latex file plus 4 ps files of figures submitted togther in
uuencoded form; invited talk presented by L. E. Gordon at the XXXI Rencontres
de Moriond on QCD and High Energy Hadronic Interactions, Les Arcs, France,
March, 199
On charged impurity structures in liquid helium
The thermoluminescence spectra of impurity-helium condensates (IHC) submerged in superfluid helium have
been observed for the first time. Thermoluminescence of impurity-helium condensates submerged in superfluid
helium is explained by neutralization reactions occurring in impurity nanoclusters. Optical spectra of excited
products of neutralization reactions between nitrogen cations and thermoactivated electrons were rather different
from the spectra observed at higher temperatures, when the luminescence due to nitrogen atom recombination
dominates. New results on current detection during the IHC destruction are presented. Two different mechanisms
of nanocluster charging are proposed to describe the phenomena observed during preparation and warmup
of IHC samples in bulk superfluid helium, and destruction of IHC samples out of liquid helium
Collisional damping of surface waves in the solar corona
The damping of surface waves by viscosity and heat conduction is evaluated. For the solar corona, it is found that surface waves dissipate efficiently only if their periods are shorter than a few tens of seconds and only if the background magnetic field is less than about 10 Gauss. Heating of quiet coronal regions is possible if the coronal waves have short periods, but they cannot heat regions of strong magnetic field, such as coronal active region loops
Effects of high and low barometric pressures on susceptibility and resistance to infection Quarterly status report, 1 Apr. - 30 Jun. 1970
Effects of high and low barometric pressures on susceptibility and resistance to infectio
- …