Opportunities for Spectroscopy of super heavy elements



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tarix27.02.2018
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#28336


Opportunities for Spectroscopy of super heavy elements


Overview

  • In-beam Spectroscopy of SHE is a very successful technique

  • Complementary to Decay Studies

  • Optical Studies



Scientific Goals

  • Single Particle structure of SHE

  • Detailled in-beam spectroscopy of nuclei

  • from Cf to Ds and beyond

  • Anchor “floating” chains

  • Ideally follow the stability line…

  • … or at least stay as close to it as possible.



Why study transfermiums?



Magic Shells



Important for ground state properties:

  • Important for ground state properties:

    • Mass (≠ Q-value)
    • Spin + Parity
    • Decay modes
    • Lifetime
    • Shape
  • Confirmation of chains

    • Unambiguous (Z,N) identification




Experience with gamma and CE studies

  • Experience with gamma and CE studies

  • Unique set of problems

  • Main challenge is Fission



251Md



251Md



MoI 2



Isomers

  • Provide information on quasiparticle states

  • Indirect evidence for isomer in 254No seen in the 1970s

  • A. Ghiorso et al, PRC 7 (1973) 2032

  • Several searches in JYFL and ANL



Isomer Tagging



Interpretation



Which Cases?



How to get there?

  • Available Targets:

    • 208Pb, 209Bi (Cold fusion)
    • 232Th, 238U, 243Am, 248Cm (Hot Fusion)
  • Beams: Far out.



Up, up and away



Start from the beam: 132Sn



Promising

  • The combination of N=82 targets and doubly magic 132Sn should be favourable.

  • Unfortunately they have the highest Coulomb barriers 

  • Lots of angular momentum 



High spin states in SHE



Nuclear Identification



Target

  • Target

  • High beam quality needed

  • Prompt Spectrometer capable of high rate

  • EXOGAM, AGATA

  • Separator with large transmission

  • gas-filled Separator needed for EURISOL

  • Excellent Recoil ID

  • DAQ capable of high rate: Triggerless, Digital



Dominant channel is constant ~0.1 - 1b Fission. This limits Ge rate!

  • Dominant channel is constant ~0.1 - 1b Fission. This limits Ge rate!

  • Target wheel spokes need beam sweeping

  • High granularity and large distance to keep individual rates low (AGATA!)

  • Background from entrance windows etc.

    • Need windowless system!


AGATA (Advanced GAmma Tracking Array) 4 -array for Nuclear Physics Experiments at European accelerators providing radioactive and high-intensity stable beams



Fission does not readily produce CE

  • Fission does not readily produce CE

  • SHE produce more CE than Gamma

  • Delta electrons require HV barrier

  • Generally difficult

  • Rate concentrated near field axis

  • Baseline dirty -> need digital cards





SAGE







In-beam studies will need to be assessed individually but will be possible

  • In-beam studies will need to be assessed individually but will be possible

  • Decay Spectroscopy is vital

  • Optical Spectroscopy provides complementary information

  • Exciting Times!



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