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C. Romig , J. Beller, J. Isaak, N. Pietralla, D. Savran, M. Scheck,

C. Romig , J. Beller, J. Isaak, N. Pietralla, D. Savran, M. Scheck, K. Sonnabend, J. Wagner, M. Zweidinger Institut für Kernphysik, Technische Universität Darmstadt, Darmstadt, Germany H.R. Weller, M. Ahmed, E. Kwan, R. Raut, G. Rusev, S.C. Stave, A. Tonchev, W. Tornow

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C. Romig , J. Beller, J. Isaak, N. Pietralla, D. Savran, M. Scheck,

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  1. C. Romig, J. Beller, J. Isaak, N. Pietralla, D. Savran, M. Scheck, K. Sonnabend, J. Wagner, M. Zweidinger Institut für Kernphysik, Technische Universität Darmstadt, Darmstadt, Germany H.R. Weller, M. Ahmed, E. Kwan, R. Raut, G. Rusev, S.C. Stave, A. Tonchev, W. Tornow Departement of Physics, Duke University, Durham, NC, USA D. Deleanu, D.M. Filipescu, T. Glodariu, N.-V. Zamfir National Institute for Physics and Nuclear Engineering „Horia Hulubei“ , Bucharest-Magurele, Romania March 11th, 2011 | Christopher Romig | Technische Universität Darmstadt | AG Pietralla | ELI-NP: The Way Ahead Investigation of Parity Quantum Numbers with Laser Compton Back-Scattered PhotonsELI-NP: The Way Ahead – 10-12 March, 2011

  2. March 11th, 2011 | Christopher Romig | Technische Universität Darmstadt | AG Pietralla | ELI-NP: The Way Ahead Nuclear Resonance Fluorescence • Nuclear Resonance Fluorescence (NRF): excitation of nuclear level by resonant absorption of real photon and subsequent decay by reemission of a photon • low momentum transfer  spin selective to dipole excited states • observables: level energy, spin quantum number, parity quantum number, branching ratios, and transition strengths • important tool for investigation of nuclear structure at low energies

  3. March 11th, 2011 | Christopher Romig | Technische Universität Darmstadt | AG Pietralla | ELI-NP: The Way Ahead Determination of Parities in NRF • determination of parity quantum numbers requires polarization measurements • measurement of polarization in exit channel difficult because of low analyzing power ( <10%) • using polarized photons in entrance channel is preferable: • analyzing power is ≈ 100% (energy-independent) • parity information obtained by relatively simple intensity measurements M. Buessing et al., Phys. Rev. C 78 041602(R) (2008)

  4. March 11th, 2011 | Christopher Romig | Technische Universität Darmstadt | AG Pietralla | ELI-NP: The Way Ahead Determination of Parities in NRF • polarization plane (E-vector) • incident photon • beam E1 transition M1 transition

  5. March 11th, 2011 | Christopher Romig | Technische Universität Darmstadt | AG Pietralla | ELI-NP: The Way Ahead Determination of Parities in NRF • experimental asymmetry E1 transition M1 transition N. Pietralla et al., Phys. Rev. Lett. 88 012502 (2002)

  6. March 11th, 2011 | Christopher Romig | Technische Universität Darmstadt | AG Pietralla | ELI-NP: The Way Ahead Physics • Electric Dipole response: • Pygmy Dipole Resonance • Two-Phonon State [1] A.I. Titov et al., J. Phys. G: Nucl. Part. Phys. 32 1097 (2006) http://irfu.cea.fr/Sphn/Parity/ • parity violation (PV) effect postulated in 1956 and experimentally verified in 1957 by Wu et al. • various theoretical and experimental attempts but impact of weak interaction on nuclear structure not well tested, yet • 1+/1- doublet in 20Ne suggested [1] to be one of best cases to study PV • Magnetic Dipole response: • Scissors Mode • Spin-Flip Excitations

  7. March 11th, 2011 | Christopher Romig | Technische Universität Darmstadt | AG Pietralla | ELI-NP: The Way Ahead 1- isobaric analogs 11270 (5) 1- T=1 11262.3(19) 1+ 5+ 2+ 4+ 3+ 0+ 20Ne The 20Ne Case: Parity Mixing of Yrast Levels p(d5/21)n(d5/23) p(p3/21)n(d5/23) 1+ [1] A.I. Titov et al., J. Phys. G: Nucl. Part. Phys. 32 1097 (2006) gs 20F, T< = 1 • doublet is isobaric analog of simple shell model states • effect of PV is expected to be very small • high nuclear enhancement factor [1]: • overlapping wavefunctions • small energy splitting (large uncertainty) • feasibility of measurment of PV effect on 20Ne? T<=0

  8. March 11th, 2011 | Christopher Romig | Technische Universität Darmstadt | AG Pietralla | ELI-NP: The Way Ahead Measurement on 20Ne • target: natural neon gas (90.48% 20Ne) with 2400 psi • 28Si target for energy calibration and determination of analyzing power • container: aluminum core wrapped in carbon fiber T.C. Li et al., Phys. Rev. C 73 054306 (2006) • beam energy: 11.26 MeV (ΔE ≈ 350 keV) • 4 h with circular polarized photons (isotropic emission -> reference point) • 20 h with linear polarized photons (separation of 1+ and 1- state)

  9. March 11th, 2011 | Christopher Romig | Technische Universität Darmstadt | AG Pietralla | ELI-NP: The Way Ahead 20Ne – Spectra and Preliminary Results • before: • now (preliminary): 20Ne 1- vertical 1+ 28Si: 1+ 28Si: 1- 20Ne horizontal 28Si: 1+ 1+ 1- • 20Ne doublett: strong M1 and weak E1 excitation • energy difference from analysis of peak centroids in both measurements

  10. March 11th, 2011 | Christopher Romig | Technische Universität Darmstadt | AG Pietralla | ELI-NP: The Way Ahead Summary

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