Single and double coincidence nucleon spectra in the

E. BAUER, G. GARBARINO, A. PARREÑO Y A. RAMOS

NUCLEAR PHYSICS A

Elsvier

Lugar: Amsterdam; Año: 2010 p. 199 - 224

0375-9474

Single and double coincidence nucleon spectra in the weak decay of $Lambda$hypernuclei are studied within a nuclear matterformalism extended to finite nuclei via the local density approximation.With respect to previous calculations,the present work adopts a unified microscopic approach forboth the one-- and two--body induced mechanisms,including the channels $Lambda nn o nnn$ and$Lambda pp o npp$ in addition to the mode $Lambda np o nnp$ alreadyconsidered in earlier phenomenological studies.The propagation of the finalnucleons in the residual nucleus is simulated by an intranuclear cascade code.Through the comparison of our predictions with $^{12}_Lambda$C KEKnucleon coincidence data obtained with a nucleon kineticenergy threshold of 30 MeV and an opening angle region$cos heta_{NN}leq -0.7$ we determine$Gamma_n/Gamma_p=0.66pm 0.24$.We find that the value of $Gamma_n/Gamma_p$ extracted from single nucleon distributionsis strongly affected by final state interaction effects. Somediscrepancies between measured and calculated proton spectra are alsopointed out.