Semiclassical Distorted Wave Model Analysis of the (π−,K+)(\pi^-,K^+) Σ\Sigma Formation Inclusive Spectrum

$(\pi^-,K^+)$ hyperon production inclusive spectra with $p_\pi =1.2$ GeV/c measured at KEK on $^{12}$C and $^{28}$Si are analyzed by the semiclassical distorted wave model. Single-particle wave functions of the target nucleus are treated using Wigner transformation. This method is able to account for the energy and angular dependences of the elementary process in nuclear medium without introducing the factorization approximation frequently employed. Calculations of the $(\pi^+,K^+)$ $\Lambda$ formation process, for which there is no free parameter since the $\Lambda$ s.p. potential is known, demonstrate that the present model is useful to describe inclusive spectra. It is shown that in order to account for the experimental data of the $\Sigma^-$ formation spectra a repulsive $\Sigma$-nucleus potential is necessary whose magnitude is not so strong as around 100 MeV previously suggested.Comment: 12 pages, 10 figures, accepted in Phys. Rev.

Mesure d'activité des émetteurs α par ciné-nucléographie

Nous donnons les résultats de mesures d'activité de sources de polonium par le ciné-nucléographe. Pour des sources de quelques dizièmes à quelques centièmes de microcurie, les résultats sont concordants à 2 pour I00 près avec ceux donnés par les méthodes classiques de mesures. Ceci permet de prévoir l'utilisation du ciné-nucléographe dans des domaines d'activité (de quelques microcuries à quelques millicuries) où les appareils habituels sont défaillants ou imprécis

On the Q-value of the Tau-Decay

The Q-value of the π-decay has been determined in photographic emulsions, by a procedure which, using the joint information given by ranges and angles of the secondary particles, excludes the need of a given B-E relation known a priori. The results obtained on a statistics of 45 events is:Q = (74.9 ±0.4) MeV. An empirical expression for the B-E relation for π-mesons valid in the velocity interval 0.27 < Β < 0.67 is obtained: log [(E/m πc 2)·10 3] = 1.649 + 0.566 log R mm+ 0.010 (log R mm 2. The standard deviation on the energy derived from a given mean range by this relation is 0.5%. © 1956 Società Italiana di Fisica.SCOPUS: ar.jinfo:eu-repo/semantics/publishe