High-Spin Isomers in Neutron-Rich Nuclei Studied with the TARDIS-array at IGISOL
Nuclear physics
Nuclear Inst. and Methods in Physics Research, A, Volume 373, Issue 3, p. 415-420 (1996).
Authors:
G. Lhersonneau, P. A. Butler, J. F. C. Cocks, A. Honkanen, M. Huhta, P. M. Jones, A. Jokinen, R. Julin, S. Juutinen, A. Lampinen, D. Müller, E. Mäkelä, M. Oinonen, J. M. Parmonen, M. Piiparinen, A. Savelius, J. F. Smith, S. Törmänen, A. Virtanen, J. Äystö
Summary
The study introduces the TARDIS (Target and Recoil Decay Spectroscopy) array, a 12-detector Compton-suppressed γ-ray spectrometer integrated with the IGISOL (Ion Guide Isotope Separator On-Line) facility. Designed to investigate high-spin isomers in neutron-rich nuclei produced via fission, the setup enables precision spectroscopy of short-lived isotopes by coupling rapid mass separation with high-efficiency γ-ray detection.
In a benchmark experiment on ⁹⁷Y (populated through ²³²Th(p, X) reactions at 25 MeV), the TARDIS array demonstrated a >10-fold improvement in sensitivity compared to earlier reactor-based setups.
Key achievements include:
- Enhanced Detection: The array's Compton suppression and fast timing capabilities resolved weak γ-ray transitions (e.g., in ⁹⁷Y → ⁹⁷Zr decay) previously obscured by background, enabling precise reconstruction of isomer decay schemes.
- Isomer Identification: High-spin states in ⁹⁷Y were characterized, with γ-γ coincidence data revealing rotational band structures and isomeric transitions critical for understanding deformation and shell effects near N=603.
- Technical Innovation: The IGISOL-TARDIS coupling allowed in-source spectroscopy of fission fragments with half-lives as short as ~100 ms, overcoming limitations of conventional offline methods.
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