Positive Identification of Two Alpha-Particle-Emitting Isotopes of Element 104

We have studied isotopes of element 104 formed by bombarding ²⁴⁹Cf with ¹²C and ¹³C ions. ²⁵⁷104 and ²⁵⁹104 were positively identified by milking their daughters, ²⁵³No and ²⁵⁵No. ²⁵⁷104 is a 4.5-sec alpha-particle activity with a complex spectrum; ²⁵⁹104 is likewise an alpha emitter with a half-life of 3 sec. ²⁵⁸104 is tentatively identified as an 11-msec spontaneous-fission activity.