Transition Effect in Lead of Star-Producing Radiation


IN a previous communication1, we reported our measurements on the absorption at 3,500 m. above sea-level of star-producing radiation in lead and in other materials. The data from the absorption in lead, which were the most abundant of all, pointed to the existence of a transition effect with a maximum at about 20 gm./cm.2. As this result, of particular interest in discussing the origin of the stars, was not in agreement with the results of other workers2, we carried out some new observations so as to obtain better statistical data. Though our data are not yet completely collected, we can now affirm that the transition effect in lead really exists ; and we wish to point out its particular property, namely, that it is produced almost entirely by the three-prong stars. This result is in agreement with some orientation measurements made by Amaldi and co-workers3 with fast ionization chambers.

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  1. 1

    Bernardini, G., Cortini, G., and Manfredini, A., Nuovo Cimento, 5, 511 (1948); Phys. Rev., 74, 845 (1948).

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  2. 2

    George, E. P., and Jason, A. C., private communication.

  3. 3

    private communication.

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CORTINI, G., MANFREDINI, A. Transition Effect in Lead of Star-Producing Radiation. Nature 163, 991–992 (1949).

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