Hypernuclei formation probability as a function of the atomic mass number A

The creation of a hypernucleus [2], that is a nucleus in which a nucleon is replaced by an hyperon, requires the injection of strangeness into the nucleus. This is possible in different ways [3], mainly using π+ or K− beams on nuclear targets; recently, also electron beams have been used. The FINUDA experiment at the DAΦNE Φ factory of the INFN “Laboratori Nazionali di Frascati” produced Λ-hypernuclei by stopping, in thin nuclear targets (0.1-0.2 g/cm2), the negative kaons originating from the Φ decay through the strangeness-exchange reaction K−st o p +A Z →AΛ Z + π − , where A Z indicates
the target nucleus and AΛZ the Λ hypernucleus in which a Λ particle replaced a neutron. FINUDA, an unconventional and
innovative apparatus, allowed the positioning of 8 different target modules around the interaction region. In this way different
targets could be studied contemporaneously, with the same apparatus and with the same analysis technique, allowing for a
direct comparison between different nuclei. In particular FINUDA could study the production of Λ-hypernuclei on 7Li, 9Be,
12C, 13C and 16O targets. Both the Λ binding energy and the hypernuclei production probabilities have been measured [1].
The new measurements on 7 Li, 9 Be, 13C and 16O, along with previous measurements on 12C, allowed for a meaningful study
ΛΛΛΛ Λ
of the formation of p-shell hypernuclei from the two-body capture of K− at rest, giving for the first time the possibility of disentangling the effects due to atomic wave-function of the captured K− from those due to the pion optical nuclear potential and from those due to the specific hypernuclear states [4].