E1: Search for Superheaby Elements (SHE)

Search for SHE has been one of challenging subjects in nuclear physics and has been studied at lots of laboratories in the world such as DUBNA (Russia), LBL (USA), GSI (Germany), etc. The element found at GSI with atomic number 111 is the heaviest one at preset. The (HI, alpha+xn) reaction is found to be very effective for production of SHE;, since it is shown to occur even nuclear the Coulomb barrier in 40Ar induced reaction on 209Bi and alpha emission can efficiently cool down a highly excited nucleus both in energy and angular momentum. Based on the idea, the measurement of the cross section of the 209Bi (40Ar, alpha+xn)245-xEs reactions has been done using the gas-filled recoil isotope separator (GARIS) developed in the cyclotron Laboratory. The results provide very promising evidence for the production of SHE. Further experiments searching for heavier elements are now in progress.

Photograph of Gass-filled recoil separator (GARIS) and ion- guide isotope separator (IGISOL)
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