Measuring octupole collectivity in 221Rn using Coulomb excitation at MINIBALL, & SPEDE
George O’Neill
Octupole collectivityCertain nucleon configurations have reflection asymmetry
Enhanced Schiff moments due to nearly degenerate parity doublets
Induce atomic electric-dipole moments
Octupole moment measured through E3 transition
[1] ‘Octupole collectivity in 220Rn and 224Ra’, L. Gaffney, PhD thesis, 2012
221-RadonParity doublet splitting only possible in odd mass systems [2]
Theoretically, asymmetry strongest @ Z=88, N=134
Good beam achievable at ISOLDE
Internal conversion dominates some transitions vs gamma decay
221Rn, 1x105 ion/s48 hour beam time120Sn target, 2 mg/cm2
REX-ISOLDERadioactive ion beam – Radioactive beam EXperiment at ISOLDE
Protons incident on UCX target
Accelerates up to 3.0 MeV/u
MINIBALLCoulomb excitation
Gamma detector array with DSSSD
144 segments of encapsulated Ge
Currently offline for HIE-ISOLDE upgrade
Results so far
201.0 ↓
223.5 ↓
289.3 ↓
Kβ1
↓
Kα1, Kα2
↓
221Rn, 6x103 ion/s30 hour beam time120Sn target, 2 mg/cm2
Results so far
201.0 ↓
223.5 ↓
289.3 ↓
Kβ1
↓
Kα1, Kα2
↓
7/2+, 0 keV
223.5 keV
22.5 keV7/2+, 0 keV
201.0 keV 223.5 keV
SPEDE - motivationSPectrometer for Electron DEtection
Si detector in backwards geometry
Allows full picture
Can also be used for other useful physics
SPEDE – where we areBeam time applied for at JYFL
Detector ordered
Preamplifiers tested
On track for installation Q4 2014
SummarySome initial results for 221Rn
SPEDE will enhance knowledge of nucleus
Should have first results by 2015
1. ‘Octupole collectivity in 220Rn and 224Ra’, L. Gaffney, PhD thesis, 2012
2. ‘Reflection-asymmetric shapes in odd-A actinide nuclei’, Nucl. Phys. A529 (1991), S. Ćwiok, W. Nazarewicz
3. ‘Combined in–beam γ–ray and conversion electron spectroscopy with radioactive ion beams’, P. Papadakis, J. Pakarinen (JYFL proposal)
221Rn CollaborationCEA
Dr Marie-Delphine Salsac, Dr Magda Zielinska
Technischen Universität DarmstadtProf Thorsten Kröll, Dr Marcus Scheck, Sabine Bönig, Michael Thürauf
University of FloridaProf C.Y. Wu
University of JyväskyläDr Tuomas Grahn, Joonas Konki, Sanna Stolze
University of CologneDr Nigel Warr, Lars Lewandowski, Burkhard Siebeck, Tim Steinbach, Andreas Vogt
KVI GroningenDr Lorenz Willman
KU LeuvenDr Liam Gaffney, Dr Kasia Wrzosek-Lipska, Tim De Coster, Nele Kesteloot
University of LiverpoolProf Peter Butler, George O'Neill
University of MichiganProf Tim Chupp
Yale UniversityDr Christian Bernards
SummarySome initial results for 221Rn
SPEDE will enhance knowledge of nucleus
Should have first results by 2015
1. ‘Octupole collectivity in 220Rn and 224Ra’, L. Gaffney, PhD thesis, 2012
2. ‘Reflection-asymmetric shapes in odd-A actinide nuclei’, Nucl. Phys. A529 (1991), S. Ćwiok, W. Nazarewicz
3. ‘Combined in–beam γ–ray and conversion electron spectroscopy with radioactive ion beams’, P. Papadakis, J. Pakarinen (JYFL proposal)