New Measurement of the Cosmic-Ray Positron Fraction from 5 to 15 GeV

We present a new measurement of the cosmic-ray positron fraction at energies between 5 and 15 GeV with the balloon-borne HEAT-pbar instrument in the spring of 2000. The data presented here are compatible with our previous measurements, obtained with a different instrument. The combined data from the three HEAT flights indicate a small positron flux of non-standard origin above 5 GeV. We compare the new measurement with earlier data obtained with the HEAT-e+- instrument, during the opposite epoch of the solar cycle, and conclude that our measurements do not support predictions of charge sign dependent solar modulation of the positron abundance at 5 GeV.Comment: accepted for publication in PR

Energy Spectra, Altitude Profiles and Charge Ratios of Atmospheric Muons

We present a new measurement of air shower muons made during atmospheric ascent of the High Energy Antimatter Telescope balloon experiment. The muon charge ratio mu+ / mu- is presented as a function of atmospheric depth in the momentum interval 0.3-0.9 GeV/c. The differential mu- momentum spectra are presented between 0.3 and about 50 GeV/c at atmospheric depths between 13 and 960 g/cm^2. We compare our measurements with other recent data and with Monte Carlo calculations of the same type as those used in predicting atmospheric neutrino fluxes. We find that our measured mu- fluxes are smaller than the predictions by as much as 70% at shallow atmospheric depths, by about 20% at the depth of shower maximum, and are in good agreement with the predictions at greater depths. We explore the consequences of this on the question of atmospheric neutrino production.Comment: 11 pages, 8 figures, to appear in Phys. Rev. D (2000

Characterization and radiation testing of the Harris HS9008RH flash analogue to digital converter

Results from tests characterizing the performance and radiation hardness of the HS9008RH flash analog to digital convertor (FADC) are presented. These tests were performed primarily to evaluate the suitability of this device for use in the GEM Central Tracker at the SSC experiment. Basic performance characteristics and susceptibility of these characteristics to radiation were examined. Performance test results indicate that the device integral nonlinearity is sampling rate dependent and worsens rapidly above a sampling rate of 15 megasamples per second (MSPS). No degradation in performance of the device was observed after its exposure of up to 81 Mrad of 1.25 MeV [gamma] radiation from a 60Co source. Exposure of the device to a reactor fast neutron fluence (E > 100 keV) of 5 x 1014/cm2 resulted in no significant observed performance degradation as well.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/31505/1/0000427.pd

The Energy Spectra and Relative Abundances of Electrons and Positrons in the Galactic Cosmic Radiation

Observations of cosmic-ray electrons and positrons have been made with a new balloon-borne detector, HEAT (the "High-Energy Antimatter Telescope"), first flown in 1994 May from Fort Sumner, NM. We describe the instrumental approach and the data analysis procedures, and we present results from this flight. The measurement has provided a new determination of the individual energy spectra of electrons and positrons from 5 GeV to about 50 GeV, and of the combined "all-electron" intensity (e+ + e-) up to about 100 GeV. The single power-law spectral indices for electrons and positrons are alpha = 3.09 +/- 0.08 and 3.3 +/- 0.2, respectively. We find that a contribution from primary sources to the positron intensity in this energy region, if it exists, must be quite small.Comment: latex2e file, 30 pages, 15 figures, aas2pp4.sty and epsf.tex needed. To appear in May 10, 1998 issue of Ap.

Problems and Paradoxes in Economic and Social Policies of Modern Welfare States

Relationships between economic growth rates and the expansion of welfare expenditures in Western nations are examined. The point is made that real gross national product grew rapidly from about 1959 until about 1973, but that since 1973 it has either grown slowly or not at all, while welfare expenditures and entitlements have continued to escalate. Forecasts of a variety of important economic variables in these countries for the near term are presented and discussed, and it is concluded that despite the current modest economic improvement, difficulties in funding welfare states will continue throughout the remainder of the 1980s. Some consideration is given to problems in welfare states to the end of the century, and further difficulties in funding and managing these states are forecast for this period as well. Problems of welfare states are not regarded as short-term by-products of maladjustments experienced in the Western world in the last 10 years but rather as long-term characteristics.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/67103/2/10.1177_000271628547900102.pd

Elemental energy spectra of cosmic rays measured by CREAM-II

We present new measurements of the energy spectra of cosmic-ray (CR) nuclei from the second flight of the balloon-borne experiment CREAM (Cosmic Ray Energetics And Mass). The instrument (CREAM-II) was comprised of detectors based on different techniques (Cherenkov light, specific ionization in scintillators and silicon sensors) to provide a redundant charge identification and a thin ionization calorimeter capable of measuring the energy of cosmic rays up to several hundreds of TeV. The data analysis is described and the individual energy spectra of C, O, Ne, Mg, Si and Fe are reported up to ~ 10^14 eV. The spectral shape looks nearly the same for all the primary elements and can be expressed as a power law in energy E^{-2.66+/-0.04}. The nitrogen absolute intensity in the energy range 100-800 GeV/n is also measured.Comment: 4 pages, 3 figures, presented at ICRC 2009, Lodz, Polan