Overview In-beam Spectroscopy of SHE is a very successful technique Complementary to Decay Studies Optical Studies
Scientific Goals Single Particle structure of SHE 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 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
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 Beta Tagging Tricky, need gamma Fission Tagging Easy, not unique
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.
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 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 Optical Spectroscopy provides complementary information Exciting Times!
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