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Measuring octupole collectivity in 221 Rn using Coulomb excitation at MINIBALL, & SPEDE

Measuring octupole collectivity in 221 Rn using Coulomb excitation at MINIBALL, & SPEDE. George O’Neill. Octupole collectivity. Certain nucleon configurations have reflection asymmetry Enhanced Schiff moments due to nearly degenerate parity doublets Induce atomic electric-dipole moments

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Measuring octupole collectivity in 221 Rn using Coulomb excitation at MINIBALL, & SPEDE

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  1. Measuring octupole collectivity in 221Rn using Coulomb excitation at MINIBALL, & SPEDE George O’Neill

  2. Octupole collectivity • Certain 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

  3. 221-Radon • Parity 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 time 120Sn target, 2 mg/cm2

  4. REX-ISOLDE • Radioactive ion beam – Radioactive beam EXperiment at ISOLDE • Protons incident on UCX target • Accelerates up to 3.0 MeV/u

  5. MINIBALL • Coulomb excitation • Gamma detector array with DSSSD • 144 segments of encapsulated Ge • Currently offline for HIE-ISOLDE upgrade

  6. Results so far Kα1, Kα2 ↓ 221Rn, 6x103ion/s30 hour beam time 120Sn target, 2 mg/cm2 Kβ1 ↓ 223.5 ↓ 201.0 ↓ 289.3 ↓

  7. Results so far Kα1, Kα2 ↓ 223.5 keV 201.0 keV 223.5 keV 22.5 keV 7/2+, 0 keV 7/2+, 0 keV Kβ1 ↓ 223.5 ↓ 201.0 ↓ 289.3 ↓

  8. SPEDE - motivation • SPectrometer for Electron DEtection • Si detector in backwards geometry • Allows full picture • Can also be used for other useful physics

  9. SPEDE – where we are • Beam time applied for at JYFL • Detector ordered • Preamplifiers tested • On track for installation Q4 2014

  10. Summary • Some initial results for 221Rn • SPEDE will enhance knowledge of nucleus • Should have first results by 2015 • ‘Octupole collectivity in 220Rn and 224Ra’, L. Gaffney, PhD thesis, 2012 • ‘Reflection-asymmetric shapes in odd-A actinide nuclei’, Nucl. Phys. A529 (1991), S. Ćwiok, W. Nazarewicz • ‘Combined in–beam γ–ray and conversion electron spectroscopy with radioactive ion beams’, P. Papadakis, J. Pakarinen(JYFL proposal)

  11. 221Rn Collaboration • CEA Dr Marie-DelphineSalsac, Dr Magda Zielinska • TechnischenUniversität Darmstadt Prof Thorsten Kröll, Dr Marcus Scheck, Sabine Bönig, Michael Thürauf • University of Florida ProfC.Y. Wu • University of Jyväskylä DrTuomasGrahn, JoonasKonki, SannaStolze • University of Cologne Dr Nigel Warr, Lars Lewandowski, BurkhardSiebeck, Tim Steinbach, Andreas Vogt • KVI Groningen Dr Lorenz Willman • KU Leuven Dr Liam Gaffney, DrKasiaWrzosek-Lipska, Tim De Coster, NeleKesteloot • University of Liverpool Prof Peter Butler, George O'Neill • University of Michigan Prof Tim Chupp • Yale University Dr Christian Bernards

  12. Summary • Some initial results for 221Rn • SPEDE will enhance knowledge of nucleus • Should have first results by 2015 • ‘Octupole collectivity in 220Rn and 224Ra’, L. Gaffney, PhD thesis, 2012 • ‘Reflection-asymmetric shapes in odd-A actinide nuclei’, Nucl. Phys. A529 (1991), S. Ćwiok, W. Nazarewicz • ‘Combined in–beam γ–ray and conversion electron spectroscopy with radioactive ion beams’, P. Papadakis, J. Pakarinen(JYFL proposal)

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