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NASA NTRS1986

Secondary production of neutral pi-mesons and the diffuse galactic gamma radiation

Isobaric and scaling model predictions of the secondary spectra of neutral pi-mesons produced in proton-proton collisions, at energies between threshold and a few GeV, are compared on the basis of accelerator data and found to show the isobaric model to be superior. This model is accordingly used, in conjuction with a scaling model representation at high energies, in a recalculation of the pi exp (0) gamma-radiation's contribution to the diffuse galactic gamma background; the cosmic ray-induced production of photons (whose energy exceeds 100 MeV) by such radiation occurs at a rate of 1.53 x 10 to the -25 photons/(s-H atom). These results are compared with previous calculations of this process as well as with COS-B observations of the diffuse galactic gamma-radiation.

Dermer, C. D.↗

NASA NTRS1973

Celestial diffuse gamma radiation above 30 MeV observed by SAS-2

The Small Astronomy Satellite (SAS)-2, launched on November 15, 1972, carried into orbit a 32-deck magnetic-core digitized spark chamber gamma ray telescope to study celestial gamma radiation in the energy range above 30 MeV. In the study of several regions with b sub 2 15 deg, a finite, diffuse flux of gamma rays with a steep energy spectrum in the energy region from 35 to 200 MeV is observed. Representing the energy spectrum by a power law of the form dJ/dE = AE to - alpha power over this energy range, alpha is found along with the integral flux above 100 MeV. Combining this result with existing low energy gamma ray data yields an energy spectrum which is not a simple power law in energy, as in the X-ray region, but which demonstrates first an increase and then a decrease in slope, consistent within uncertainties with that predicted by cosmological theories, including the continuous production of high energy gamma rays primarily from neutral pi mesons throughout the history of the universe.

Fichtel, C. E.↗

NASA NTRS1978

Superdense neutron matter

A relativistic theory of high-density matter is presented which takes into account the short-range interaction due to the exchange of spin-2 mesons. An equation of state is derived and used to compute neutron-star properties. The prediction of the theory for the values of maximum mass and moment of inertia for a stable neutron star are 1.75 solar masses and 1.68 by 10 to the 45th power g-sq cm, in very good agreement with the presently known observational bounds. The corresponding radius is found to be 10.7 km. It is found that the inclusion of the spin-2 interaction reduces the disagreement between the relativistic and nonrelativistic theories in their predictions of masses and moments of inertia.

Canuto, V.↗

NASA NTRS2004

MESTRN: A Deterministic Meson-Muon Transport Code for Space Radiation

A safe and efficient exploration of space requires an understanding of space radiations, so that human life and sensitive equipment can be protected. On the way to these sensitive sites, the radiation fields are modified in both quality and quantity. Many of these modifications are thought to be due to the production of pions and muons in the interactions between the radiation and intervening matter. A method used to predict the effects of the presence of these particles on the transport of radiation through materials is developed. This method was then used to develop software, which was used to calculate the fluxes of pions and muons after the transport of a cosmic ray spectrum through aluminum and water. Software descriptions are given in the appendices.

Blattnig, Steve R.↗