1 Introduction

Cosmic Rays are energetic particles, which come to us from outer space, and are measured either through satellites, balloons, or Earth based experiments. These energetic particles interact, and the result of these interactions are the spallation products as well as gamma rays. Gamma rays arise either from collisionally excited nuclei or nuclear fragments, or as a continuum from $\pi$-decay.

The origin of cosmic rays is still a question (Hess 1912; Kohlhörster 1913; Fermi 1949; Fermi 1954; Ginzburg & Syrovatskij 1963; Ginzburg & Syrovatskij 1969; Hayakawa 1969; Berezinsky et al.${\,}$1990) which is not finally settled. The debate has reached a consensus, that most are produced in the shockwaves of supernova explosions (Baade & Zwicky 1934; Shklovskii 1953; Ginzburg 1953a, 1953b; Lagage & Cesarsky 1983; Drury 1983; Blandford & Eichler 1987; Berezhko & Krymskii 1988; Jones & Ellison 1991; Ginzburg 1993; Ginzburg 1996), be it into the interstellar medium, or into a stellar wind (Völk & Biermann 1988; Silberberg et al.${\,}$1990; Biermann 1993a). Many of the relevant issues here have been dealt with in the review by Hillas (1984) and in the books by Hayakawa (1969), Berezinsky et al. (1990) and Gaisser (1990).

Here we are concerned with the interactions of cosmic rays (CRs) in the Galaxy, and so we will adopt the picture that indeed the cosmic ray particles originate in the shocks of supernova explosions, and thus limit ourselves to the corresponding energies. This paper is motivated by three arguments: 1) the wish to further develop the cosmic ray theory initiated some time ago (Biermann 1993a, 1993c), 2) by the apparent discrepancy between the observed gamma-spectrum of the Galaxy (Hunter et al.${\,}$1997) and the expected spectrum, and 3) by the apparent discrepancy between the turbulent spectrum required by standard cosmic ray transport theory (Garcia-Munoz et al.${\,}$ 1987), and the normal observations of the interstellar medium (ISM).

The structure of this paper is as follows: first we briefly summarize the proposal to account for the origin of cosmic rays; then we go through the arguments for interaction with the material close to the progenitor star; then we briefly address the issue where the interaction happens which produces the observed gamma ray emission from the Galaxy. Finally we draw some conclusion and make some specific predictions.