ELI & FAIR: A Natural Pair Nuclear Structure w ELI & FAIR: A Natural Pair Nuclear Structure w. Photon Beams Norbert Pietralla, TU Darmstadt DAAD BMBF DAAD 21. Oct. 2011 | Norbert Pietralla @ NuSTAR-week | Experiments with Real Photons 7. Mai 2018 |

Outline Nuclear physics with low-energy photons (nuclear dipole physics) Impact of photon beams from Laser Compton Backscattering Recent progress at Duke‘s HIS Proof of Principle: 32S Pygmy Dipole Resonance: 138Ba Spin-Orbit Splitting: 40Ar Weak Coupling of Single Particles: 207Pb Parity Doublet : 20Ne Research potential of -ray beams from Laser Compton Backscattering Summary 21. Oct. 2011 | Norbert Pietralla @ NuSTAR-week | Experiments with Real Photons

Nuclear Physics with MeV-range photon beams Pure EM-interaction (nuclear-) model independent “small“ cross sections, thick targets Minimum projectile mass min. angular momentum transfer, spin-selective: dipole-modes Polarisation „Parity Physics“ Narrow Bandwidth (at ELI) „Selective Manipulation of Nuclear States“ 21. Oct. 2011 | Norbert Pietralla @ NuSTAR-week | Experiments with Real Photons

Role of Isovector Spin-flip M1 excitations in Nuclear Physics (MeV) Nucleon-Spin-flip Quark-Spin-flip 21. Oct. 2011 | Norbert Pietralla @ NuSTAR-week | Experiments with Real Photons

Induced 3N-Interaction in EFT Isovector M1 excitation of 48Ca Vlow-k interaction 3N-forces from EFT SPEs self-consistently calculated in many-body perturbation theory S-DALINAC data J.Holt, A.Schwenk et al., subm. to PRL 21. Oct. 2011 | Norbert Pietralla @ NuSTAR-week | Experiments with Real Photons

Electric Giant Dipol Resonance (GDR) Protons Neutrons E1 GDR in 197Au GDR-Strength vs A Sensitive to average Proton-Neutron-Restoring Force but insensitive to shell structure: need low-energy E1/M1 data ! 21. Oct. 2011 | Norbert Pietralla @ NuSTAR-week | Experiments with Real Photons Data from: A.Bohr, B.Mottelson “Nuclear Structure”

E1 Strength Distribution Energy/MeV Strength 5 10 15 GDR Pygmy Quadrupol/Oktupol 21. Oct. 2011 | Norbert Pietralla @ NuSTAR-week | Experiments with Real Photons

Photonuclear Reactions Separation threshold Absorption ´  ´  A´Y  gs AX Nuclear Resonance Fluorescence (NRF) Photoactivation Photodisintegration (-activation) 21. Oct. 2011 | Norbert Pietralla @ NuSTAR-week | Experiments with Real Photons

Traditionally Bremsstrahlung: Kneissl,Pietralla,Zilges, J. Phys Traditionally Bremsstrahlung: Kneissl,Pietralla,Zilges, J.Phys.G 32, R217 (2006). 21. Oct. 2011 | Norbert Pietralla @ NuSTAR-week | Experiments with Real Photons

Scissors Mode of Deformed Nuclei (A.Richter, Darmstadt, 1983) classically: current loop => M1 magnetic dipole excitation electron scattering photon scattering Bohle et al., NPA 458, 205 (1986). 21. Oct. 2011 | Norbert Pietralla @ NuSTAR-week | Experiments with Real Photons

M1 phenomena in the nuclear valence shell Collectivity of the Scissors Mode Richter, Kneissl, von Brentano et al. Stuttgart-Darmstadt-Köln Measure of quadrupole collectivity 1+ 2+ E2 M1 N. Pietralla et al., PRC 58, 184 (1998) 21. Oct. 2011 | Norbert Pietralla @ NuSTAR-week | Experiments with Real Photons

S-DALINAC at TU Darmstadt 1 2 i 1 2 Photon Experiments 10 MeV Injector: Photon Scattering / Photofission < 30 MeV Tagger: Photodesintegration / Photon Scattering Source 130 MeV Electron LINAC Electron Source 21. Oct. 2011 | Norbert Pietralla @ NuSTAR-week | Experiments with Real Photons

Darmstadt Low-Energy Photon Scattering Site at S-DALINAC Ge(HP) g-detectors Cu Cu < 10 MeV Target g e- Radiator target Electrons Bremsstrahlung E < 10 MeV Intensity Intensity Energie Energie 21. Oct. 2011 | Norbert Pietralla @ NuSTAR-week | Experiments with Real Photons

21. Oct. 2011 | Norbert Pietralla @ NuSTAR-week | Experiments with Real Photons

Is this really all E1 strength ? Systematics of the Pygmy Dipole Resonance Concentration around 5-7 MeV Strong fragmentation Summed strength: Scaling with N/Z ? Is this really all E1 strength ? core skin A. Zilges et al., PLB 542 (2002) 43. S. Volz et al., NPA 779 (2006) 1. U. Kneissl et al., J.Phys.G 32, R217 (2006). 21. Oct. 2011 | Norbert Pietralla @ NuSTAR-week | Experiments with Real Photons

Polarimetry with linearly polarized photon beams Scattering intensity distribution for linearly polarized photons 21. Oct. 2011 | Norbert Pietralla @ NuSTAR-week | Experiments with Real Photons

21. Oct. 2011 | Norbert Pietralla @ NuSTAR-week | Experiments with Real Photons

21. Oct. 2011 | Norbert Pietralla @ NuSTAR-week | Experiments with Real Photons

21. Oct. 2011 | Norbert Pietralla @ NuSTAR-week | Experiments with Real Photons

21. Oct. 2011 | Norbert Pietralla @ NuSTAR-week | Experiments with Real Photons

21. Oct. 2011 | Norbert Pietralla @ NuSTAR-week | Experiments with Real Photons

21. Oct. 2011 | Norbert Pietralla @ NuSTAR-week | Experiments with Real Photons

HIS Beam Profile; Parity of Pygmy Resonance HIS data 138Ba Polarized photon beam HIS 2002 Compton-polarimeter EUROBALL Cluster 1999 N. Pietralla et al. Phys. Rev. Lett. 88, 012502 (2002) 21. Oct. 2011 | Norbert Pietralla @ NuSTAR-week | Experiments with Real Photons

Testing shell structure from M1 Spin-flip excitation 21. Oct. 2011 | Norbert Pietralla @ NuSTAR-week | Experiments with Real Photons

Proton Spin-Orbit Force near 40Ca p-n are in different shells “Otsuka mechanism” 40Ar HIS data 40Ar T.C.Li, NP et al. Phys. Rev. C 73, 054306 (2006). 21. Oct. 2011 | Norbert Pietralla @ NuSTAR-week | Experiments with Real Photons

21. Oct. 2011 | Norbert Pietralla @ NuSTAR-week | Experiments with Real Photons

Astrophysical Relevance of M1 Data Langanke et al., PRL (2004). Neutrino-cross sections Darmstadt data 54Fe 21. Oct. 2011 | Norbert Pietralla @ NuSTAR-week | Experiments with Real Photons

Collective Valence-Shell Structures Two-Phonon Structures quadrupole-octupole symmetric/mixed-symmetric 92Zr 96Mo HIS data C. Fransen, NP et al., Phys. Rev. C 70, 044317 (2004) 21. Oct. 2011 | Norbert Pietralla @ NuSTAR-week | Experiments with Real Photons

21. Oct. 2011 | Norbert Pietralla @ NuSTAR-week | Experiments with Real Photons

21. Oct. 2011 | Norbert Pietralla @ NuSTAR-week | Experiments with Real Photons

Testing single particle contributions to complex nuclear states 207Pb HIS data 21. Oct. 2011 | Norbert Pietralla @ NuSTAR-week | Experiments with Real Photons

Polarization in the entrance channel Parity Physics Polarization in the entrance channel Linear polarization (HIS) spin/parity programme (since 2001) Circular polarization (HIS, S-DALINAC) parity non-conservation 20Ne target g circular Forward-backward asymmetry ? Parity-violation Weak interaction -θ θ 21. Oct. 2011 | Norbert Pietralla @ NuSTAR-week | Experiments with Real Photons

20Ne case: parity mixing of yrast levels 20F, T< = 1 1- 1+ 3+ 4+ 5+ 2+ p(d5/21)n(d5/23) gs ΔE=7.5±5.7 keV “enhancement factor” 670 ± 7000 Γ(1-) ≤ 0.3 keV Γ(1+) ? 1+ 1- 11270±5 11262±3 20Ne 0+ T=1 isobaric analog states Goal: measure parity violation in simple states ! Understand effects of weak interaction microscopically ► e.g., study the parity doublet in 20Ne ! T<=0 21. Oct. 2011 | Norbert Pietralla @ NuSTAR-week | Experiments with Real Photons

20Ne: Parity Mixing of Yrast States 21. Oct. 2011 | Norbert Pietralla @ NuSTAR-week | Experiments with Real Photons

20Ne/28Si in linearly/circularly polarized γ-beam 21. Oct. 2011 | Norbert Pietralla @ NuSTAR-week | Experiments with Real Photons

20Ne/28Si in linearly/circularly polarized γ-beam 21. Oct. 2011 | Norbert Pietralla @ NuSTAR-week | Experiments with Real Photons

HIS is unique and complementary Increased intensity summary New data: beam time Sept. 2007 203,205Tl 206,207,208Pb 40Ar HIS is unique and complementary Increased intensity Strong nuclear Structure program: keep it well going ! 21. Oct. 2011 | Norbert Pietralla @ NuSTAR-week | Experiments with Real Photons

Summary Nuclear structure physics with -ray beams is a vivid field with high discovery potential ELI can become a major facility in this field Needs: energy-tunable, high-flux, high-rep.rate, high-resolution, polarized -ray beam from LASER-Compton backscattering All this will be possible at ELI ! Future w. high Brightness: ELI & FAIR 21. Oct. 2011 | Norbert Pietralla @ NuSTAR-week | Experiments with Real Photons

Thank you ! 21. Oct. 2011 | Norbert Pietralla @ NuSTAR-week | Experiments with Real Photons

21. Oct. 2011 | Norbert Pietralla @ NuSTAR-week | Experiments with Real Photons

Importance of the Proton-Neutron Interaction Occupation-number dependence of spe‘s Dominant origin for shape-phase transition Dominates evolution of collectivity and deformation Study observables that are directly sensitive to the proton-neutron interaction in the valence shell ! Rick Casten‘s Textbook Read it! 21. Oct. 2011 | Norbert Pietralla @ NuSTAR-week | Experiments with Real Photons

Scissors mode of deformed nuclei Darmstadt, 1983 Achim Richter (γ, γ‘) (e,e‘) Predicted by Lo Iudice & Palumbo, 1978 @ 3 MeV: Iachello, 1981 in IBM Bohle et al., NPA 458, 205 (1986). DALINAC data 21. Oct. 2011 | Norbert Pietralla @ NuSTAR-week | Experiments with Real Photons

94Mo: the „hydrogen atom“ for MS structure M1 as unique signature for MS states 21. Oct. 2011 | Norbert Pietralla @ NuSTAR-week | Experiments with Real Photons

Superconducting-DArmstadt LINear electron ACcelerator (S-DALINAC) 130 MeV in-house electron linac TM010 -mode acceleration „cw“ beam at 3 GHz („S“-band) Ideal for nuclear structure studies Thanks to State of Hesse TU Darmstadt DFG 21. Oct. 2011 | Norbert Pietralla @ NuSTAR-week | Experiments with Real Photons 7. Mai 2018 |

Electron and Proton Scattering on 94Mo S-DALINAC data   O.Burda et al., Phys.Rev.Lett. 99, 093502 (2007) One-phonon states are strongly excited in (e,e‘) and (p,p‘) scattering experiments   21. Oct. 2011 | Norbert Pietralla @ NuSTAR-week | Experiments with Real Photons 7. Mai 2018 |

Ex „GQR“ Valence shell 2+p 2+ms 2+n 2+1 Conclusions Vmix Understanding of transition densities requires configurations „beyond the valence shell“. IBM (valence shell model) unable to predict behaviour of transition densities. QPM serves here as „full theory“ (no effective charges,…). IBM (valence shell model) can be considered „effective low-energy theory“ (effective interaction, effective charges,...). Effective models possible because of clear separation of scales (~2 MeV vs. ~20 MeV). „GQR“ Valence shell 2+p 2+ms Vmix 2+n 2+1 21. Oct. 2011 | Norbert Pietralla @ NuSTAR-week | Experiments with Real Photons

Summary Nuclear structure physics: exciting topic of quantum many-body physics Theory developments: from solid QCD to effective nuclear theory Key-role of pn-interaction for formation of collective structures Proton-neutron mixed-symmetry states: sensitive to effective pn-interaction in the valence shell Isovector character of MSS first measured directly from transition radii New signature for pn-mixed-symmetry states First firm observation of mixed-symmetry state in radioactive isotope Experimental methods available for research with „rare isotope beams“ FAIR under construction FAIR nuclear structure programme is starting right now (the students [and professors] can‘t wait…) 21. Oct. 2011 | Norbert Pietralla @ NuSTAR-week | Experiments with Real Photons

Many Thanks… P.von Brentano, J.Jolie, Ch.Fransen (Köln) T.Ahn, L.Coquard, T.Möller, G.Rainovski, Ch.Walz, O.Burda, P.von-Neumann-Cosel, M.Danchev, C.Stoyanov, D.Tarpanov J.Wambach, V.Yu.Ponomarev, R.V.Jolos P.Reiter (Köln), V.Werner,R.F.Casten (Yale) J.Gerl, J.Leske, P.Boutachkov, E.Merchan, N.Goel, M.Reese, Ch.Stahl B.Alikhani, O.Möller, A.Heinz, Ph.John, A.Givechev, N.Kurz, H.Schaffner Many more PhD/M.Sc./B.Sc.-students for their enthusiasm DAAD BMBF 21. Oct. 2011 | Norbert Pietralla @ NuSTAR-week | Experiments with Real Photons

Summary Nuclear structure physics: exciting topic of quantum many-body physics Theory developments: from solid QCD to effective nuclear theory Key-role of pn-interaction for formation of collective structures Proton-neutron mixed-symmetry states: sensitive to effective pn-interaction in the valence shell Isovector character of MSS first measured directly from transition radii New signature for pn-mixed-symmetry states First firm observation of mixed-symmetry state in radioactive isotope Experimental methods available for research with „rare isotope beams“ FAIR under construction FAIR nuclear structure programme is starting right now (the students [and professors] can‘t wait…) 21. Oct. 2011 | Norbert Pietralla @ NuSTAR-week | Experiments with Real Photons

Generic Aspects of Nuclear Structure: (and topic of this presentation) Heavy Atomic nucleus strongly coupled many-body system consists of two equivalent entities (protons-neutrons) quantum system Two-fluid quantum system COLLECTIVITY ISOSPIN SYMMETRY SHELL STRUCTURE How do these features coexist, interplay, and compete? What are the dominant mechanisms and forces? 21. Oct. 2011 | Norbert Pietralla @ NuSTAR-week | Experiments with Real Photons

Principle of a Compton-Polarimeter Parity Measurements Principle of a Compton-Polarimeter 21. Oct. 2011 | Norbert Pietralla @ NuSTAR-week | Experiments with Real Photons

Modest polarisation sensitivity Better use polarized -ray beams ! 21. Oct. 2011 | Norbert Pietralla @ NuSTAR-week | Experiments with Real Photons

21. Oct. 2011 | Norbert Pietralla @ NuSTAR-week | Experiments with Real Photons 7. Mai 2018 |

Resolution Scale and Simple Pattern shell structure: interacting nucleons Cooper pairing: N s,d boson system Collective motion: nuclear shapes 21. Oct. 2011 | Norbert Pietralla @ NuSTAR-week | Experiments with Real Photons

Identification of One- and Two-phonon MSSs 21. Oct. 2011 | Norbert Pietralla @ NuSTAR-week | Experiments with Real Photons 7. Mai 2018 |

Evidence for common structure of MSSs 21. Oct. 2011 | Norbert Pietralla @ NuSTAR-week | Experiments with Real Photons 7. Mai 2018 |

Isovector Giant Dipole Resonance (IVGDR) Protons Neutrons Strength of IVGDR vs A GDR in 197Au Sensitive to average pn-restoring force However, insensitive to shell structure 21. Oct. 2011 | Norbert Pietralla @ NuSTAR-week | Experiments with Real Photons