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HASP--SPECIAL REPORT ON HIGH ALTITUDE SAMPLING PROGRAM

Description: The results of the HASP program to determine the role played by the stratosphere in the world-wide distribution of radioactive fall-out from nuclear weapons tests are presented. The program has operated since the fall of 1957. The sampling network using U-2 aircraft collected 10/sup 8/ scf of air from 57 S to 71 N up to 70,000 ft. Ashcan data are used for upward extrapolation. IPC Paper 1478 of near 100% efficiency is used. Stratospheric ruatter sampled is in the 0.01- mu range. Stratospheric inventories of Sr/sup 90/ were calculated for the periods Nov. 1957 to Dec. 1958, Jan. to Aug 1959, and Sept. to Nov. 1959 to be, respectively, 0.95, 0.81, and 0.7 megacuries. Concentrations were greater in the Northern Hemisphere by a factor of 2 to 3 than in the Southern Hemisphere. The Sr/sup 90/ maximum cccurs in the equatorial regions around 90,000 ft and slopes down to around 70,000 ft in the polar regions. Little fractionation is noted in stratospheric debris. Cesium-137 to strontium90 ratios are 1.8 to 0.5. A semiempirical application of Gaussisn diffusion is described which suggests that hot clouds injected in the equatorial stratosphere spread in the North-South direction with mixing coefficients near 5 x 10/sup 8/ cm/sup 2// sec. Vertical mixing is slower with coefficients of 4 x 10/sup 3/ and 2 x 10/sup 4/ cm/sup 2//sec suggested for tropical and polar regions, respectively. An Injection-Depletion model is offered which indicates that as much as 50% of the material Produced in 1-Mt ground-surface burst comes down in local fall-out. Removal from the stratosphere occurs at different rates, depending on altitude and latitude of injection and season of the year. Effective half-residence times of 5, 10, snd 20 months, respectively, for polar, lowequatorial and high- equatorial debris are suggested. Surface concentrations of Sr/sup 90/ ...
Date: June 1, 1960
Creator: Stebbins, A.K. III ed.
Partner: UNT Libraries Government Documents Department

The CMBR spectrum

Description: Here we give an introduction to the observed spectrum of the Cosmic Microwave Background Radiation (CMBR) and discuss what can be learned about it. Particular attention will be given to how Compton scattering can distort the spectrum of the CMBR. An incomplete bibliography of relevant papers is also provided.
Date: May 1, 1997
Creator: Stebbins, A.
Partner: UNT Libraries Government Documents Department

On the computation of CMBR anisotropies from simulations of topological defects

Description: Techniques for computing the CMBR anisotropy from simulations of topological defects are discussed with an eye to getting as much information from a simulation as possible. Here we consider the practical details of which sums and multiplications to do and how many terms there are.
Date: May 1, 1997
Creator: Stebbins, A. & Dodelson, S.
Partner: UNT Libraries Government Documents Department

On the meaning of [Delta]T/T

Description: One of the most interesting aspects of the discovery of Microwave Background Radiation (MBR) anisotropy by the COBE satellite is the ability to compare these anisotropies with the amplitude of density inhomogeneities we measure. Combining these two, we can get a unified'' view of the inhomogeneities present in our universe on a broad range of scales. To make this comparison we must be able to translate [Delta]T/T into [delta]p/[bar p], the mass overdensity. This latter quantity we may try to determine from the distribution of galaxies and their velocities.
Date: February 1, 1993
Creator: Stebbins, A.
Partner: UNT Libraries Government Documents Department

Development of NIR detectors and science driven requirements forSNAP

Description: Precision near infrared (NIR) measurements are essential for the next generation of ground and space based instruments. The SuperNova Acceleration Probe (SNAP) will measure thousands of type Ia supernovae upto a redshift of 1.7. The highest redshift supernovae provide the most leverage for determining cosmological parameters, in particular the dark energy equation of state and its possible time evolution. Accurate NIR observations are needed to utilize the full potential of the highest redshift supernovae. Technological improvements in NIR detector fabrication have lead to high quantum efficiency, low noise detectors using a HgCdTe diode with a band-gap that is tuned to cutoff at 1:7 1m. The effects of detector quantum efficiency, read noise, and dark current on lightcurve signal to noise, lightcurve parameter errors, and distance modulus ?ts are simulated in the SNAP sim framework. Results show that improving quantum efficiency leads to the largest gains in photometric accuracy for type Ia supernovae. High quantum efficiency in the NIR reduces statistical errors and helps control systematic uncertainties at the levels necessary to achieve the primary SNAP science goals.
Date: May 23, 2006
Creator: Brown, M.G.; Bebek, C.; Bernstein, G.; Bonissent, A.; Carithers,B.; Cole, D. et al.
Partner: UNT Libraries Government Documents Department