  Formation mechanisms of single, twin, and double hypernuclei from Xi^-
absorption at rest on 12C are investigated with an refined microscopic
transport model, that incorporates the recently developed Quantal Langevin
treatment into Antisymmetrized Molecular Dynamics. The quantum fluctuations
suppress the formation probability of double hyperfragments to around 10%,
which is comparable to the experimental data, and the dynamical formation of
twin hyperfragment can be described qualitatively.
