Summary
By means of direct observations of the neutral decay modes Λ→n+π0 and K 01 →π0+π0 of Λ’s and K0’s produced in a 21 liter liquid xenon bubble chamber exposed to 1.0 GeV and 1.1 GeV π− beams at the Bevatron, we measured the branching ratios
, in agreement with predictions of the |ΔI|=1/2 rule. The fraction of all K0’s which did not decay into π++π− or π0+π0 in a time of the order of 10−10 s isX K=0.47±0.03, as expected from the particle mixture description of the K0. Λ’s produced in xenon exhibit an « up-down » asymmetry associated with a polarization of the Λ normal to the production plane, although this polarization is not as great as that observed for Λ’s produced by similar beams in hydrogen. No significant forward-backward decay asymmetry of the Λ with respect to its own line of flight is found. Strange particle production cross-sections in xenon are reported.
Riassunto
Per mezzo della osservazione diretta dei processi neutri di decadimento Λ→n+π0 e K 01 →π0+π0 dei Λ e K0 prodotti in una camera a bolle a xenon da 21 litri esposta ai fasci di π− da 1.0 ed 1.1 GeV del bevatrone, abbiamo misurato i rapporti di branching
, che sono in accordo con le predizioni della legge |ΔI|=1/2. La frazione di K0 che non decadono in π++π− oppure π0+π0 in un intervallo dell’ordine di 10−10 s èX K=0.47±0.03 quale ci si attende dalla descrizione della miscela di particelle del K0. I Λ prodotti nello xenon presentano una asimmetria alto-basso associata ad una polarizzazione normale al piano di produzione, per quanto questa polarizzazione non sia elevata come quella osservata in Λ prodotti da fasci analoghi nell’idrogeno. Non si riscontra alcuna significativa asimmetria di decadimento avanti-indietro del Λ rispetto alla sua propria traiettoria. Si riportano le sezioni trasversali per la produzione di particelle strane.
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Work supported in part by United States Atomic Energy Commission.
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Brown, J.L., Bryant, H.C., Burnstein, R.A. et al. Properties of neutral strange particles produced in a xenon bubble chamber. Nuovo Cim 19, 1155–1170 (1961). https://doi.org/10.1007/BF02731391
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DOI: https://doi.org/10.1007/BF02731391