The first observation of the neutron-rich hypernucleus HΛ6

A similar investigation has been carried out for the observation of the neutron-rich hypernucleus HeΛ9 by looking for the Kstop−+Be9→HeΛ9+π+ reaction in coincidence with the HeΛ9→Li9+π− mesonic weak decay; an upper limit for the production rate of HeΛ9 undergoing the two-body decay has been found to be 4.2⋅10−6/Kstop− (90% C.L.).