Sulla distribuzione in energia delle particelle emesse nelle evaporazioni nucleari

Riassunto

Si espone un metodo per determinare la distribuzione in energia dei rami delle «stelle», metodo basato sulla misura delle proie-zioni delle tracce, e non sulla misura della granulazione. Si danno i risultati dell'applicazione del metodo alla statistica ricavata da misure eseguite su circa 4000 stelle prodotte dai raggi cosmici a 3500 m s.l.m.

Summary

The experimental data about the particles in the nuclear evaporations and their energy spectrum are considered. The results by other Authors, obtained with the grain-couting of the tracks, are discussed and an estimate is given of the errors involved both in the grain-counting method and in the method of the direct measurement of the range of the tracks ending in the emulsion: the last one avoids the difficulties involved in the calculation of the energy from the grain-counting results. In Tables I-a and 1-b the figures are collected resulting by the measurements of the projections of 2248 protons and 2272 α-particles'-tracks stopping in the emulsion, out from a total number of 18701 prongs of 4007 observed stars. A method is developed to deduce from the distribution of the tracks-projection (Tables II-a and II-b, fig. 1 and 2) the actual range-spectrum of the particles. The range-spectrum (fig. 4 and 5) and then the energy spectrum (fig. 6 and 7) are so obtained for the «evaporated» protons and α-particles. The total numbers of proton and α-tracks are calculated from the curves of fig. 4 and 5 and a comparison is made with the total number of the observed prongs. The agreement between the two figures is shown to be fairly good.