Prompt and Delayed Conversion Electron Spectroscopy of Heavy Nuclei

1
Prompt and Delayed Conversion Electron
Spectroscopy of Heavy Nuclei

• Andreas Heinz
• A. W. Wright Nuclear Structure Laboratory
• Yale University
• ATLAS Workshop, August 8-9, 2009

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Prompt Conversion Electron Spectroscopy
254No
R.-D. Herzberg et al., EPJA (2009)
253No
SACRED
P. A. Butler et al., PRL 89, 202501 (2002)
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Solenoids and Mini Oranges
ICEBall M.P. Metlay et al., NIM A 336, 162
(1993)
? low detection efficiency below 200 keV. ?
threshold is too high for heavy nuclei.
Solenoid spectrometers with superconducting
(Super-e, SACRED), and normal-conducting coils
(SAGE), as well as with permanent magnet guides
exist.
J. Andrzejewski et al., NIM A 585, 155 (2008)
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Needs for Heavy Nuclei

• High detection efficiency also at low energies.
• e-gamma, e-e, gamma-gamma correlations i.e. a
  spectrometer coupled to GAMMASPHERE/GRETINA.
• Channel selection (coupled to FMA)
• Usable at high beam currents.

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Complex Alpha Decay Spectra
257Rf
a
ICE
Spectra are distorted by summing of alpha and
conversion electron signals! But we get the sum
energy of a converted decay cascade!
253No
G. D. Jones, NIM A 488, 471 (2002)
DSSD
a
Recoil
ICE
6
Ranges
SRIM
25 µm at 50 keV
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Needs for Delayed Conversion Electrons

• High detection efficiencies and resolution -
  especially at low electron energies.
• Alpha-electron coincidences
• Electron-gamma coincidences

e spectrometer?
253Fm
Catcher (active?)
Recoils
Ge
Degrader (active?)
M. Asai et al., PRL 95, 102502 (2005)
Ge