Speaker
Description
The existence of long-lived super heavy elements depends on the presence of shell gaps that increase nuclear stability against fission. The "Island of Stability" (IoS) is predicted to have the largest gaps, specifically around atoms with proton number Z=114, 120 and neutron number N=184. Small energy gaps occurring near Z=100,108 and N=152,162 also enhance the stability of heavy actinides and trans-actinides, creating a sort of "submerged rift" leading to the IoS. The structure properties of actinides near these deformed shell gaps provide imporant benchmarks for theoretical models on superheavy elements and the IoS.
At the JAEA Tandem we used gamma-ray spectroscopy to study the structure of actinides near $^{252}$Fm. Recent results, which include new information on K isomers in $^{248}$Cf (Z=98,N=150)[1] and the ground state rotational band and moment of inertia of 252Fm, will be presented.
One experimental factor that limits the study of heavy actinides is the low detection efficiency for low-energy transitions (<60 keV), which are typical of rotational bands in this region. A possible solution, provided by a new array of CdTe detectors that we are currently develping, will also be discussed.
[1] R. Orlandi et al.. Phys. Rev C 106, 064301 (2022).
[2] R. Orlandi et al., Submitted for publication.