G. Godfrey

Cosmic-Ray Background Flux Model based on a Gamma-Ray Large-Area Space Telescope Balloon Flight Engineering Model

Cosmic-ray background fluxes were modeled on the basis of existing measurements and theories and are presented here. The model, originally developed for the Gamma-Ray Large Area Space Telescope (GLAST) balloon experiment, covers the entire solid angle (4π sr), the sensitive energy range of the instrument (~10 MeV to 100 GeV), and the abundant components (proton, alpha particle, e-, e+, μ-, μ+, and gamma ray). It is expressed in analytic functions in which modulations due to solar activity and the Earths geomagnetism are parameterized. Although the model is intended to be used primarily for the GLAST balloon experiment, model functions in low Earth orbit are also presented and can be used for other high-energy astrophysical missions. The model has been validated via comparison with the data of the GLAST balloon experiment.

OBSERVATION OF X-RAY VARIABILITY IN THE BL LACERTAE OBJECT 1ES 1959+65

This paper reports X-ray spectral observations of a relatively nearby (z = 0.048) BL Lac object 1ES 1959+65, which is a potential TeV emitter. The observations include 31 short pointings made by the Unconventional Stellar Aspect (USA) experiment on board the Advanced Research and Global Observation Satellite (ARGOS), and 17 pointings by the Proportional Counter Array (PCA) on board the Rossi X-Ray Timing Explorer (RXTE). Most of these observations were spaced by less than 1 day. 1ES 1959+65 was detected by the ARGOS USA detector in the range 1-16 keV, and by the PCA in the 2-16 keV range but at different times. During the closely spaced RXTE observations beginning on 2000 July 28, the ending of one flare and the start of another are visible, associated with spectral changes, where the photon index Γ ranges between ~1.4 and ~1.7, and the spectrum is harder when the source is brighter. This implies that 1ES 1959+65 is an X-ray-selected BL Lac type (XBL) blazar, with the X-ray emission likely to originate via the synchrotron process. The USA observations reveal another flare that peaked on 2000 November 14 and doubled the flux within a few days, again associated with spectral changes of the same form. The spectral variability correlated with the flux and timing characteristics of this object that are similar to those of other nearby BL Lac objects and suggest relativistic beaming with a Doppler factor δ ≥ 1.6 and magnetic fields on the order of a few milligauss. We also suggest that the steady component of the X-ray emission—present in this object as well as in other XBLs—may be due to the large-scale relativistic jet (such as measured by Chandra in many radio-loud active galactic nuclei) but pointing very closely to our line of sight.

The Electron Spectrum From B-meson Decays

The Crystal Ball Collaboration has measured the energy spectrum of electrons from semileptonicB meson decays at thee+e− storage ring DORIS II. Branching ratios and weak mixing angles of the Kobayashi-Maskawa matrix are determined using several models for the hadronic matrix elements. We obtain the branching ratio for semileptonic.B decays to charmed states BR(B→evXc)=(11.7±0.4±1.0)%. Our result for the corresponding Kobayashi-Maskawa matrix element is |Vcb|=0.052±0.006. The model dependence of both results is included in the error. We have not observed semileptonicB decays to non-charmed mesons. Analyzing the measured electron spectrum above 2.4 GeV, where nob→c decays contribute, we find BR(B→evXu)/BR(B→evXc)<6.5% at the 90% confidence level. This corresponds to an upper limit |Vub/Vcb|<0.21.

Determination ofГ ee of the Υ(1S) and Υ(2S) resonances, and measurement ofR atW=9.39 GeV

AbstractUsing the Crystal Ball detector operating at the DORIS II storage ring we have measured the leptonic partial widthsГee of the Υ(1S) and Υ(2S) resonances. We findn

Limits on axion and light Higgs boson production in ϒ (1S) decays

Gamma _{ee} (Upsilon (1S)) = 1.34 pm 0.03 pm 0.06keV

The USA X-ray timing experiment

n andn

USA experiment on the ARGOS satellite: a low-cost instrument for timing x-ray binaries

Gamma _{ee} (Upsilon (2S)) = 0.56 pm 0.04 pm 0.02keV.