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May 13 th, 2014 | 11 th Intl. Spring Seminar on Nucl. Physics | Progress on M1-Research | Prof. Dr. Dr. h.c. Norbert Pietralla | IKP, TU-Darmstadt | 1 Norbert Pietralla, TU Darmstadt PROGRESS ON M1 RESEARCH Thanks to organizers and influential contributions of Aldo C.! Outline Motivation New experimental techniques and approaches Relativistic M1-projectile COULEX: V ls in exotic nuclei ( 85 Br) M1-precision measurements: towards nuclear charge currents ( 6 Li) M1-scissors mode: How wide does it open? ( 156 Gd) Summary

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May 13 th, 2014 | 11 th Intl. Spring Seminar on Nucl. Physics | Progress on M1-Research | Prof. Dr. Dr. h.c. Norbert Pietralla | IKP, TU-Darmstadt | 2 Motivation Nuclear Quasideuteron-Configurations: A.F.Lisetskiy et al., Phys. Rev. C 60, 064310 (1999).

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May 13 th, 2014 | 11 th Intl. Spring Seminar on Nucl. Physics | Progress on M1-Research | Prof. Dr. Dr. h.c. Norbert Pietralla | IKP, TU-Darmstadt | 3 Motivation Magnetic dipole (M1) transitions are sensitive to transition charge currents (orbital) transitional spin motion (spin-flip) and yield information on proton/neutron-structure of nuclear states local spin-orbit splitting i.e., dynamics of effective degrees of freedom in the valence-space E B

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May 13 th, 2014 | 11 th Intl. Spring Seminar on Nucl. Physics | Progress on M1-Research | Prof. Dr. Dr. h.c. Norbert Pietralla | IKP, TU-Darmstadt | 4 Tensor force, spin-orbit splitting, and evolution of shell structure T. Otsuka et al. Quest for local measurement of V ls

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May 13 th, 2014 | 11 th Intl. Spring Seminar on Nucl. Physics | Progress on M1-Research | Prof. Dr. Dr. h.c. Norbert Pietralla | IKP, TU-Darmstadt | 5 Unique experimental signature of V ls ? Spin-flip M1 transitions: direct observation of spin-orbit splitting 1p (l=1) j < = l-1/2 1p 1/2 j > = l+1/2 1p 3/2 B(M1;j ) 1 N 2 Unique signature!

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May 13 th, 2014 | 11 th Intl. Spring Seminar on Nucl. Physics | Progress on M1-Research | Prof. Dr. Dr. h.c. Norbert Pietralla | IKP, TU-Darmstadt | 6 Experimental challenge of fast M1 transitions in exotic nuclei Strong M1 transitions [B(M1) 1 N 2 ] are typically very fast [~ fs] M1 from (in)direct lifetime measurements (DSAM) difficult Classical techniques electron scattering photon scattering etc. not applicable to exotic nuclei Need new approach ! N.P. et al., NIM A 483, 556 (2002). 1 + T=1 of 32 S at 8.124 MeV ( , ) at HI S (Duke Univ.) Relativistic M1-projectile COULEX

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May 13 th, 2014 | 11 th Intl. Spring Seminar on Nucl. Physics | Progress on M1-Research | Prof. Dr. Dr. h.c. Norbert Pietralla | IKP, TU-Darmstadt | 7 Direct Characterization of Spin-Orbit Splitting (Tensor Force): 85 Br as Test Case 89 Y 87 Rb 85 Br 0.68(10) N 2 0.47(5) N 2 ???

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May 13 th, 2014 | 11 th Intl. Spring Seminar on Nucl. Physics | Progress on M1-Research | Prof. Dr. Dr. h.c. Norbert Pietralla | IKP, TU-Darmstadt | 8 Spin-Flip M1: Coulex? Coulomb excitation only E2 dominated for low energy. In-flight separation produces excotic ions with high velocity M1 Coulomb excitation is small compared to E2 excitation for nonrelativistic beams. For high velocities, M1 can have significant contribution to the total cross-section! M1 Coulomb excitation is small compared to E2 excitation for nonrelativistic beams. For high velocities, M1 can have significant contribution to the total cross-section! Discriminate E2 vs M1-contribution? I.e. how to measure the multipole mixing ratio?

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May 13 th, 2014 | 11 th Intl. Spring Seminar on Nucl. Physics | Progress on M1-Research | Prof. Dr. Dr. h.c. Norbert Pietralla | IKP, TU-Darmstadt | 9 Physics test case: proton SPE towards 78 Ni K.T. Flanagan et al., PRL 103, 142501 (2009)T. Otsuka et al., PRL 104, 012501 (2010) Z=28 Approaching 78 Ni from the left: N=40 to N=50

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May 13 th, 2014 | 11 th Intl. Spring Seminar on Nucl. Physics | Progress on M1-Research | Prof. Dr. Dr. h.c. Norbert Pietralla | IKP, TU-Darmstadt | 10 89 Y, NNDC; 87 Rb, L. Kubler et al., PRC 65, 054315; 85 Br NNDC; 83 As, NNDC and E, Sahin et al., AIP Conf. Proc. 1072, 298 (2008), 1012, 139 (2008); 81 Ga, D. Verney at al. PRC 76, 054312 (2007) 39 ESPE (kEV) 39373533 31 29 Proton V ls approaching 78 Ni: Z=40 to Z =28 2) E( p 1/2 ) evolves ??? ? 1)E( p 3/2 ) E( f 5/2 ) constant 28 50 89 Y 87 Rb 83 As 81 Ga 85 Br 79 Cu

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May 13 th, 2014 | 11 th Intl. Spring Seminar on Nucl. Physics | Progress on M1-Research | Prof. Dr. Dr. h.c. Norbert Pietralla | IKP, TU-Darmstadt | 11 Unique experimental signature of p 1/2 ? 89 Y 87 Rb 85 Br 0.68(10) N 2 0.47(5) N 2 ??? Relativistic Coulomb excitation reactions c (E2) (1/ ) 2 c (M1) independent at high v/c large M1 matrix elements significantly contribute to total COULEX yield Relativistic beam energies 50-70 % Possible at GSI Huge Doppler spread in -ray spectrum need precise Doppler correction and reduce Doppler broadening PreSPEC- AGATA

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May 13 th, 2014 | 11 th Intl. Spring Seminar on Nucl. Physics | Progress on M1-Research | Prof. Dr. Dr. h.c. Norbert Pietralla | IKP, TU-Darmstadt | 12 PreSPEC-AGATA @ GSI Schematic Setup FRS (GSI, Darmstadt) particle selection: B-E-B Particle identification: TPC tracking detectors ToF measurement Energy-loss measurement LYCCA (D.Rudolph, M.Bentley, P.Reiter et al.) Outgoing particle tracking and identification: Z identification via E-E Mass identification via E-ToF Gamma-ray detection 2012: HPGe array using pulse- -2014 shape analysis and -ray tracking techniques (AGATA) BaF&LaBr scintillators (HECTOR+) picture from C. Domingo-Pardo et al., NIM A 694, 297-312 (2012)

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May 13 th, 2014 | 11 th Intl. Spring Seminar on Nucl. Physics | Progress on M1-Research | Prof. Dr. Dr. h.c. Norbert Pietralla | IKP, TU-Darmstadt | 13 PreSPEC-AGATA in Operation March 2014 Hector AGATA LYCCA FRS Beam 85 Br 300 MeV/u ~2 10 4 pps > 99% pure

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May 13 th, 2014 | 11 th Intl. Spring Seminar on Nucl. Physics | Progress on M1-Research | Prof. Dr. Dr. h.c. Norbert Pietralla | IKP, TU-Darmstadt | 14 Experimental Challenges 1.Beam from accelerator (or in-flight separator) 2.Nuclear reaction in a fixed target 3.Excited reaction products leave the target (flight direction changes) 4.Emission of Doppler-shifted -radiation Need -energy in the rest frame of the emitting nucleus (Doppler-correction) Need the tracks of particle and -ray Spectroscopic resolution depends on accurate track reconstruction of both, -ray and particle!

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May 13 th, 2014 | 11 th Intl. Spring Seminar on Nucl. Physics | Progress on M1-Research | Prof. Dr. Dr. h.c. Norbert Pietralla | IKP, TU-Darmstadt | 15 PreSPEC-AGATA Commissioning 2012: Coulomb Excitation of 80 Kr on Gold Coulomb excitation of 80 Kr data: M.Reese (TU Darmstadt) for PreSPEC

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May 13 th, 2014 | 11 th Intl. Spring Seminar on Nucl. Physics | Progress on M1-Research | Prof. Dr. Dr. h.c. Norbert Pietralla | IKP, TU-Darmstadt | 16 PreSPEC-AGATA Commissioning, 2012 Coulomb excitation of 80 KrSecondary fragmentation of 80 Kr data: M.Reese (TU Darmstadt) for PreSPEC

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May 13 th, 2014 | 11 th Intl. Spring Seminar on Nucl. Physics | Progress on M1-Research | Prof. Dr. Dr. h.c. Norbert Pietralla | IKP, TU-Darmstadt | 17 Two Beam Energies

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May 13 th, 2014 | 11 th Intl. Spring Seminar on Nucl. Physics | Progress on M1-Research | Prof. Dr. Dr. h.c. Norbert Pietralla | IKP, TU-Darmstadt | 18 Two Beam Energies

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May 13 th, 2014 | 11 th Intl. Spring Seminar on Nucl. Physics | Progress on M1-Research | Prof. Dr. Dr. h.c. Norbert Pietralla | IKP, TU-Darmstadt | 19 M1 character of the 1191-keV -ray E2 and M1 X-sections have different energy dependence c (E2) (1/ ) 2 c (M1) independent 85 Br Measure c at two energies 200 MeV/u, 300 MeV/u Deduce || from ratio c (300MeV/u) / c (200MeV/u) Example using same strengths as in stable 87 Kr: B(M1;1/2 - 3/2 - ) = 0.58 N 2 B(E2;1/2 - 3/2 - ) 1 Wu E beam (MeV/u)v/cJJ CE (mb ) N /100h 2020.571/2 - 1.931300 3000.651/2 - 1.681170 c ( 300MeV/u ) / c ( 202MeV/u ) = 0.87

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May 13 th, 2014 | 11 th Intl. Spring Seminar on Nucl. Physics | Progress on M1-Research | Prof. Dr. Dr. h.c. Norbert Pietralla | IKP, TU-Darmstadt | 20 Two-Target Solution (TU Darmstadt) Reminder: Doppler effect Idea: 2 targets. First target thick enough to slow down beam from 300 to 200 MeV/u at the second target. All information in one measurement! Working principle: Lifetime of excited state ~50 fs. Decay happens directly after excitation. Decay position equal to exitation position Two peaks will appear due to different detection angles (Doppler-effect) Excitation in first target happens at high energy (300 MeV/u) Exitation in second target happens at lower energy (200 MeV/u) Peaks geometrically separated by Doppler-correction

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May 13 th, 2014 | 11 th Intl. Spring Seminar on Nucl. Physics | Progress on M1-Research | Prof. Dr. Dr. h.c. Norbert Pietralla | IKP, TU-Darmstadt | 21 Two-Target Solution: Simulations Simulated Peak shapes (Doppler- corrected Energy vs. detection angle): Pros: one beam energy one FRS setting same conditions for both energies thick target increased excitation prob. better peak to background ratio Cons: thick target increased angular straggling increased energy straggling increaded velocity uncertainty

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May 13 th, 2014 | 11 th Intl. Spring Seminar on Nucl. Physics | Progress on M1-Research | Prof. Dr. Dr. h.c. Norbert Pietralla | IKP, TU-Darmstadt | 22 First data on Relativistic M1-Projectile COULEX online spectra, 5 h, no Doppler corr. ~ 5% of total data data: M. Reese, C. Stahl, M. Lettmann (TU Darmstadt) 85 Br on Au Mar.2014

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May 13 th, 2014 | 11 th Intl. Spring Seminar on Nucl. Physics | Progress on M1-Research | Prof. Dr. Dr. h.c. Norbert Pietralla | IKP, TU-Darmstadt | 23 Expected Data: Realistic Simulation Doppler-correction on downstream-target Simulation efficiency from performance commissioning background from first data on 85 Br data taking finished April 2014 data-analysis time: est. 2 yrs efficiency from performance commissioning background from first data on 85 Br data taking finished April 2014 data-analysis time: est. 2 yrs Exciting new way for measuring spin-orbit splitting of exotic nuclei at FAIR ! Thanks to PreSPEC-, AGATA-collaborations, and M.Reese, C.Stahl, M.Lettmann et al. resulting sensitivity: B(M1) = 0.6(2) N 2 > 90% M1

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May 13 th, 2014 | 11 th Intl. Spring Seminar on Nucl. Physics | Progress on M1-Research | Prof. Dr. Dr. h.c. Norbert Pietralla | IKP, TU-Darmstadt | 24 M1 from orbital currents: Scissors Mode here: E2 / M1 competition TRM: N.Lo Iudice, F.Palumbo; IBM: F. Iachello; RPA: A.Faessler; SR: J. Ginocchio; M1 scissors mode: How wide does it open?

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May 13 th, 2014 | 11 th Intl. Spring Seminar on Nucl. Physics | Progress on M1-Research | Prof. Dr. Dr. h.c. Norbert Pietralla | IKP, TU-Darmstadt | 25 M1 scissors mode: Photon scattering! Nuclear Scissors Mode A.Richter, Darmstadt, 1983 Scissors mode Classically: current loop magnetic excitation: M1 M1 E2 N.P. et al., PRC 58, 184 (1998).

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May 13 th, 2014 | 11 th Intl. Spring Seminar on Nucl. Physics | Progress on M1-Research | Prof. Dr. Dr. h.c. Norbert Pietralla | IKP, TU-Darmstadt | 26 Scissors mode of 156 Gd in polarized -beam Weller et al., Prog. Part. Nucl. Phys. 62 (2009) 257 data: T. Beck (TU Darmstadt) TU Darmstadt-NRF program @ HI S N.P. et al., PRL 88, 012502 (2002). N.P. et al., NIM A 483, 556 (2002).

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May 13 th, 2014 | 11 th Intl. Spring Seminar on Nucl. Physics | Progress on M1-Research | Prof. Dr. Dr. h.c. Norbert Pietralla | IKP, TU-Darmstadt | 27 Multipole mixing ratio polarization plane 02 02 data: T. Beck (TU Darmstadt)

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May 13 th, 2014 | 11 th Intl. Spring Seminar on Nucl. Physics | Progress on M1-Research | Prof. Dr. Dr. h.c. Norbert Pietralla | IKP, TU-Darmstadt | 28 Estimate for E2-strength of scissors band Alaga Rule:(good K quantum number) expect in 2 + sc 2 + 1 transition M1 E2

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May 13 th, 2014 | 11 th Intl. Spring Seminar on Nucl. Physics | Progress on M1-Research | Prof. Dr. Dr. h.c. Norbert Pietralla | IKP, TU-Darmstadt | 29 First evidence for transition? Peak is for sure not a gs transition! (from angular distribution) E2 M1

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May 13 th, 2014 | 11 th Intl. Spring Seminar on Nucl. Physics | Progress on M1-Research | Prof. Dr. Dr. h.c. Norbert Pietralla | IKP, TU-Darmstadt | 30 3rd topic: 6 Li as Benchmark for ab-initio Nuclear Structure Theory Nuclear Quasideuteron-Configurations: A.F.Lisetskiy et al., Phys. Rev. C 60, 064310 (1999).

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May 13 th, 2014 | 11 th Intl. Spring Seminar on Nucl. Physics | Progress on M1-Research | Prof. Dr. Dr. h.c. Norbert Pietralla | IKP, TU-Darmstadt | 31 S-DALINAC at TU Darmstadt world-wide unique in EFT energy regime Recirculating superconducting LINAC Niobium cavities, LHe cooled @ 2 K, 3 GHz cw e-beams, < 130 MeV, 60 A

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May 13 th, 2014 | 11 th Intl. Spring Seminar on Nucl. Physics | Progress on M1-Research | Prof. Dr. Dr. h.c. Norbert Pietralla | IKP, TU-Darmstadt | 32 1)L. Cohen and R. Tobin, Nucl. Phys. 14(1959) 2)W.C. Barber et al., Phys. Rev. 120 (1960) 3)E.C. Booth and K.A. Wright, Nucl. Phys. 35 (1962) 4)W.C Barber et al., Phys. Rev. 41 (1963) 5)S.J. Skorka et al., Phys. Rev. 47 (1963) 6)W.L. Creten et al., Nucl. Phys. A120 (1968) 7)F. Eigenbrod, Z. Phys. 228 (1969) 8)V.K. Rasmussen and C.P. Swann, Phys. Rev. 183 (1969) 9)J.C. Bergstrom et al., Nucl. Phys. A251 (1975) 6 Li as Benchmark for ab-initio Theory 1 +,T=0 3 +,T=0 0 +,T=1 6 Li 4 He + 2 H 0 + T=0 1 + T=0 parity forbidden 3562 2185 1474 M1 Exp.: M1 =8.16(19) eV (from (e,e)) S. Pastore et al., PRC 87 (2013): chiral currents contribute significantly to M1 GFMC with one-body EM current operator at leading order (impulse approximation): 6.90(2) eV GFMC with additional two-body meson-exchange currents up to N 3 LO ( EFT): 8.41(3) eV

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May 13 th, 2014 | 11 th Intl. Spring Seminar on Nucl. Physics | Progress on M1-Research | Prof. Dr. Dr. h.c. Norbert Pietralla | IKP, TU-Darmstadt | 33 Absorption Processes resonant absorption only at resonance energies depends on Absorption lines only a few eV wide! atomic attenuation several processes contributes at each energy independent of

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May 13 th, 2014 | 11 th Intl. Spring Seminar on Nucl. Physics | Progress on M1-Research | Prof. Dr. Dr. h.c. Norbert Pietralla | IKP, TU-Darmstadt | 34 Use scatterer made of absorber material as high-resolution detector. Self Absorption: Decrease of Scattered Photons because of Resonant Absorption scatterer calibration target Principle of (Relative) Self Absorption 1 1 F. R. Metzger, Prog. in Nucl. Phys. 7 (1959) 53; N.P. et al., PRC (1994).

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May 13 th, 2014 | 11 th Intl. Spring Seminar on Nucl. Physics | Progress on M1-Research | Prof. Dr. Dr. h.c. Norbert Pietralla | IKP, TU-Darmstadt | 35 calculate R as function of self absorption R exp determined experimentally comparison gives ground-state transition width 0 B(M1) relative measurement: systematics suppressed sub-1% precision becomes feasible Determination of Ground-State Transition Width and Branching Ratio to the Ground State

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May 13 th, 2014 | 11 th Intl. Spring Seminar on Nucl. Physics | Progress on M1-Research | Prof. Dr. Dr. h.c. Norbert Pietralla | IKP, TU-Darmstadt | 36 Self Absorption Measurement on 6 Li (Ch.Romig, TU Darmstadt, PhD thesis, 2014 in preparation) scatterer: 5 g Li 2 CO 3 (enriched to 95% in 6 Li) calibration target: 4.2 g 11 B (sandwiched) absorber: 10 g Li 2 CO 3 (enriched to 95% in 6 Li) endpoint energy: 7.1 MeV 7 days w/o absorber 8 days w/ absorber R = 0.5178 0.0015 (0.3% relative uncertainty) 0 ? Stay tuned Ch.Romig, TU Darmstadt, 2014 HI S-2/ELI-NP will provide this precision for excitations 2 orders of magn. weaker ! S-DALINAC data 2013

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May 13 th, 2014 | 11 th Intl. Spring Seminar on Nucl. Physics | Progress on M1-Research | Prof. Dr. Dr. h.c. Norbert Pietralla | IKP, TU-Darmstadt | 37 Summary and Outlook Progress on M1 Research New experimental technology and methods (scientific opportunities for nuclear shell model) Availability Frontier (Relativistic M1-projectile COULEX, local V ls in radioactive exotic nuclei) Sensitivity Frontier (intense polarized -ray beams, weak channels: strong physics) Precision Frontier (high count rates, new methods)

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May 13 th, 2014 | 11 th Intl. Spring Seminar on Nucl. Physics | Progress on M1-Research | Prof. Dr. Dr. h.c. Norbert Pietralla | IKP, TU-Darmstadt | 38

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May 13 th, 2014 | 11 th Intl. Spring Seminar on Nucl. Physics | Progress on M1-Research | Prof. Dr. Dr. h.c. Norbert Pietralla | IKP, TU-Darmstadt | 39

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May 13 th, 2014 | 11 th Intl. Spring Seminar on Nucl. Physics | Progress on M1-Research | Prof. Dr. Dr. h.c. Norbert Pietralla | IKP, TU-Darmstadt | 40 1 2 Photon Experiments 10 MeV Injector: Photon Scattering / Photofission < 30 MeV Tagger: Photodesintegration / Photon Scattering Source 130 MeV Electron LINAC Electron Source Thanks to State of Hesse TU Darmstadt DFG S-DALINAC at TU Darmstadt

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May 13 th, 2014 | 11 th Intl. Spring Seminar on Nucl. Physics | Progress on M1-Research | Prof. Dr. Dr. h.c. Norbert Pietralla | IKP, TU-Darmstadt | 41 Bremsstrahlung-Site

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May 13 th, 2014 | 11 th Intl. Spring Seminar on Nucl. Physics | Progress on M1-Research | Prof. Dr. Dr. h.c. Norbert Pietralla | IKP, TU-Darmstadt | 42 Parity quantum number for J=1 states Elastic scattering distribution not isotropic about incident polarization plane. No intensity along oscillating dipole vector Azimuthal rotation by 90 o for M1 and E1 distributions Observable only for linearly polarized beam N.Pietralla, H.R. Weller et al., NIM A 483 (2002) 556.

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May 13 th, 2014 | 11 th Intl. Spring Seminar on Nucl. Physics | Progress on M1-Research | Prof. Dr. Dr. h.c. Norbert Pietralla | IKP, TU-Darmstadt | 43 1. Availability Frontier Current NRF measurements require gramm-size targets (~ 10 22-21 nuclei) Required by cross sections (~ eV b) detection efficiency (~ 10%), available luminosity (number of target nuclei times -ray flux) resonably long beam times (order of days) Rare p-process nuclei ( 106 Cd, 130 Ba, 156 Dy, 174 Hf) ~ 0.1% ab., enriched material at ~$1,000/mg Long-lived radioactive isotopes( 10 Be, 182 Hf, 250 Cm) T 1/2 > ~10,000 yrs. 51 more nuclides would become accessible to NRF A variety of scientific questions could be answered. 51 more nuclides would become accessible to NRF A variety of scientific questions could be answered.

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May 13 th, 2014 | 11 th Intl. Spring Seminar on Nucl. Physics | Progress on M1-Research | Prof. Dr. Dr. h.c. Norbert Pietralla | IKP, TU-Darmstadt | 44 2. Sensitivity Frontier Search for weak signals sensitive to the physics under study One example: Rotational Moment of Inertia of the Scissors Mode Other examples: decay branchings into sensitive channels search for predicted pygmy quadrupole resonance (PQR) measurement of decay E2/M1 multipole mixing ratios measurement of parity-mixing matrix element in 20 Ne to be continued 156 Gd @ HI S Data: J.Beller, TU Darmstadt

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May 13 th, 2014 | 11 th Intl. Spring Seminar on Nucl. Physics | Progress on M1-Research | Prof. Dr. Dr. h.c. Norbert Pietralla | IKP, TU-Darmstadt | 45 3. Precision Frontier High Intensity = High count rates small statistical uncertainties address unresolved questions that cannot be answered today because of uncertainties e.g., scaling of scissors mode with deformation evolution of K-mixing in octupole- vibrational bands of deformed nuclei the unknown unknown N. Pietralla et al., PRC 58, 184 (1998) 1+1+ 2+2+ High Intensity enables new approaches e.g. Nuclear Self Absorption