Abstract. The X-ray satellite SAX, a major program of the Italian Space Agency with participation of the Netherlands Agency for Aereospace Programs, was launched on April 30 1996 from Cape Canaveral. After launch it was renamed BeppoSAX in honour of Giuseppe (Beppo) Occhialini. The payload is characterized by a very wide spectral coverage from 0.1 to 300 keV, with well balanced performances both from its low and high energy instrumentation. Its sensitivity will allow the exploitation of the full band for weak sources (1/20 of 3C 273), opening new perspectives in the study of spectral shape and variability of several classes of objects. Furthermore, the presence of wide field cameras will allow monitoring of the long term variability of sources down to 1 mCrab and the discovery of X-ray transient phenomena. In this paper we describe the main aspects of the mission, the operations, the scientific capabilities of the instruments and the scientific objectives.

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observed until the vial was opened.4. Composition of the radioactive gas. Gas chromatography with charcoal and silica gel columns was used to analyze 1 the chemical composition of the radioactive gas liberated from 9.5-mg/cm 2 polyethylene. The composition was found to be 57% methane, 36% acetylene, 6% ethylene, and 1 % ethane. No CO or C0 2 was observed.Absolute measurements of the C X2 {p,pn)C n cross section may have been affected by the loss of C 11 in those cases where thin plastic targets were used. Recent measurements in the Bev region 2 ' 3 have used polystyrene targets sufficiently thick so that the correction is less than 1 %. The loss effect may also account for some of the discrepancies in the C 12 (p, pn)C n / Al 27 (/>, 3/m)Na 24 cross-section ratios which have been reported.The authors wish to acknowledge helpful discussions with and the assistance of R.

Although the experimental pion angular and momentum distributions have not as yet been accurately determined, the known results 2 agree qualitatively with the prediction of the static model, that the positive meson prefers to go at right angles to the photon beam, with the energy of the 3-3 resonance. Precise measurements of these quantities will be of great interest to test the details of the theory to a greater extent than is possible from total cross-section data. In particular, a more precise treatment of the Bose symmetry of the final pions may be required than that given by Cutkosky and Zachariasen. 3 These authors treated the mesons (New York) 14, 229 (1961)]. He finds a very large enhancement that could account for the remaining discrepancy with plausible parameters. Unfortunately, his calculations do not go beyond 550 MeV. It is important to ascertain whether the rescattering term gets small again at higher energy. We have also computed the interference term between Figs. 1(a) and 1(b). For an effective TTTTTTT coupling A = 5 [J. S. Ball, Phys. Rev. 124, 2014 gives |A| <1.8] the cross section is increased by about 4 ph at 500 MeV and 10 M b at 700 MeV.

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