Summary
The absorption of slow negative pions has been studied in the light nuclei helium, cabon and nitrogen. The dominant reaction in each case has been observed to be: (1) π− +4He → p + 3n; (2) π− +12C →2α+lp + 3n; (3) π− +14N → 3α + 2n. Prong distributions, proton and alpha spectra have been compiled and compared with the theory of Clark and Ruddelsden. The frequency of α-emission gives strong qualitative support to the α-particle model of nuclear structure. This is supported by the similarity of the proton spectra in reactions (1) and (2). The low average energy of protons in (1) and (2) and of α-particles in (3) supports the two nucleon recoil model in the primary absorption act. In this case (np) initial nucleon states3S1 are favored over (pp) states1S0 in agreement with the inverse reaction — production of mesons in nucleon-nucleon collisions.
Riassunto
Si è studiato l’assorbimento dei pioni negativi lenti nei nuclei leggeri, elio, carbonio e azoto. Le reazioni dominanti osservate nei singoli casi sono state: (1) π++4He → p + 3n; (2) π− +12C → 2τa + lp + 3n; (3) π− +14N → 3α+2n. Si sono prodotti e confrontati con la teoria di Clark e Ruddelsden le distribuzioni dei rami e gli spettri protonici e alfa. La frequenza di emissione α dà un forte appoggio qualitativo al modello a particelle α della struttura nucleare. Una prova a favore di tale modello è data dalla similarità degli spettri protonici nelle reazioni (1) e (2). La bassa energia media dei protoni in (1) e (2) e delle particelle α in (8) è a favore. dei modello di rinculo a due nucleoni nell’assorbimento primario. Nel caso (np), stati iniziali3S1 risultano favoriti rispetto a stati (pp)1S0, d’accordo con la reazione inversa — la produzione di mesoni nelle collisione nucleone-nucleone.
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This research is supported in part by the joint program of the Office of Naval Research and the Atomic Energy Commission.
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Ammiraju, P., Lederman, L.M. A diffusion chamber study of very slow mesons. IV. Absorption of pions in light nuclei. Nuovo Cim 4, 283–306 (1956). https://doi.org/10.1007/BF02745450
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DOI: https://doi.org/10.1007/BF02745450