Search for rare decay modes of Californium

The results ofmeasurements on the search for the cluster decay of 252 Cfnucleus with the emission ofthe bound state of eight neutrons are presented. The value of an upper limit ofthe partial probabilities for this process is obtained, which contradicts to the results ofthe recently published work, in which the possible existence of octaneutron was declared. Based on the results of our measurements, the estimations for the upper limits ofpartial probabilities for the emission of 20 C, 24 O, 28 Ne, 32Mg, 36 Si, 40 S, 40 P, and 40 Si clusters are given. The estimation for the upper limit of the partial probability of 250 Cf decay with the emission of the bound state of six neutrons is also obtained.