For about two decades, a population of relative small and nearby molecular clouds has been known to exist at high Galactic latitudes. Lying more than 10 from the Galactic plane, these clouds have typical distances of ∼150 pc, angular sizes of ∼1, and masses of order tens of solar masses. These objects are passive sources of high-energy γ-rays through cosmic ray-gas interactions. Using a new wid...

For about two decades, a population of relative small and nearby molecular clouds has been known to exist at high Galactic latitudes. Lying more than 10◦ from the Galactic plane, these clouds have typical distances of ∼150 pc, angular sizes of ∼1◦, and masses of order tens of solar masses. These objects are passive sources of high-energy γ-rays through cosmic ray-gas interactions. Using a new w...

Diffusive shock acceleration operating at expanding supernova remnant shells is by far the most popular model for the origin of galactic cosmic rays. Despite the general consensus received by this model, an unambiguous and conclusive proof of the supernova remnant hypothesis is still missing. In this context, the recent developments in gamma ray astronomy provide us with precious insights into ...

We present Linear Energy Transfer (LET) spectra calculated for the 1990-1991 CRRES mission using the galactic cosmic ray (GCR) and solar energetic particle (SEP) models developed for the CRRES/SPACERAD program and presented by Chen, et al. 1992 at this conference. We discuss how the spectra vary with changes in the galactic cosmic ray and solar energetic particle models. Finally, we illustrate ...

The diffuse gamma-ray background radiation (GBR) at high Galactic latitudes could be dominated by inverse Compton scattering (ICS) of cosmic ray (CR) electrons on the cosmic microwave background radiation (CBR) and on starlight (SL) in an extended CR halo of our galaxy. Assuming the locally observed CR electron spectrum beyond a few GeV, which follows from equilibrium between Fermi acceleration...

Observations from the Cosmic Ray Isotope Spectrometer (CRIS) aboard NASA’s Advanced Composition Explorer (ACE) have shown that all relevant galactic cosmic-ray isotopic ratios measured are consistent with an OB-association origin of galactic cosmic rays (GCRs). Additionally CRIS measurements of the isotopic abundances of Ni and Co have shown that the Ni has completely decayed into Co, indicatin...

We employ the Monte Carlo particle collision code DPMJET3.04 to determine the multiplicity spectra of various secondary particles (in addition to π 0 's) with γ's as the final decay state, that are produced in cosmic-ray (p's and α's) interactions with the interstellar medium. We derive an easy-to-use γ-ray production matrix for cosmic rays with energies up to about 10 PeV. This γ-ray productio...

The isotopes of lithium, beryllium, and boron (LiBeB) are known in nature to be produced primarily by CNO spallation and a a fusion from interactions between cosmic rays and interstellar nuclei. While the dominant source of LiBeB isotopes in the present epoch is cosmic-ray interactions, other sources are known to exist, including the production of Li from big bang nucleosynthesis. Precise obser...

Measurements of the diffuse extragalactic γ-ray background (EGRB) are complicated by a strong Galactic foreground. Estimates of the EGRB flux and spectrum, obtained by modeling the Galactic emission, have produced a variety of (sometimes conflicting) results. The latest analysis of the EGRET data found an isotropic flux Ix = 1.45 ± 0.05 above 100 MeV, in units of 10−5 ph s−1 cm−2 sr−1. We analy...