We have measured the angular correlation of the pair nucleons np and nn emitted from the nonmesonic weak decay (NMWD) of 12ΛC produced via the (π+, K+) reaction in coincidence measurement. The Λ p → n p and Λ n → n n modes were clearly identified by measuring the back-to-back correlation of the emitted nucleon pairs which is the characteristic of two-body kinematics. From the measured nucleon pair numbers Nn n and Nn p, the ratio Γn / Γp of the partial decay widths Γn (Λ n → n n) and Γp (Λ p → n p) of 12ΛC was extracted to be 0.51 ± 0.13 (stat) ± 0.05 (syst); this result is almost free from the ambiguity due to the nuclear final state interaction and 3-body decay process, which were inherent in the previous results. The obtained Γn / Γp ratio of 12ΛC (p-shell) is close to that of 5ΛHe (s-shell). The results are consistent with those of recent theoretical calculations.
|Number of pages||6|
|Journal||Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics|
|Publication status||Published - 2006 Sep 28|
- Nonmesonic weak decay
- Γ (Λ n → n n) / Γ (Λ p → n p)
ASJC Scopus subject areas
- Nuclear and High Energy Physics