Search for the neutron-rich hyper nucleus 9 He is reported by the FINUDA experiment at DANE, INFN-LNF, studying (π+,n−) pairs in coincidence from the K−stop + 9Be → 9He + π+ production reaction followed by 9He → 9Li + π− weak decay. An upper limit of the production rate of 9He undergoing this two-body π− decay is determined to be (2.3 ± 1.9) × 10−6/K− stop at the 90% confidence level.
