Spectroscopy of exotic nuclei Lecture 1

1. SpectroscopyofexoticnucleiLecture 1 Reiner Krücken Physik Department E12 Technische Universität München Maier-Leibnitz Laboratory of TU München and LMU München forNuclear-, Particle-, andAcceleratorPhysics R. Krücken - XVth UK Postgraduate School in Nuclear Physics – Lecture 1

2. Outline • Introduction • Central questions of the Physics of Exotic Nuclei • Production of radioactive ion beams • Selected Topics in the Physics of Exotic Nuclei • Nuclear Shell Structure and its Modifications in Exotic nuclei • Halos, Skins and Pygmy Resonances • Superheavy Nuclei • Shape coexistence Aim of the lectures: Discussion of current physics questions in combination with an introduction to various experimental methods R. Krücken - XVth UK Postgraduate School in Nuclear Physics – Lecture 1

3. From QCD to atomic nuclei d u u Protons, Neutrons Quarks, Gluons Light nuclei (A10) ? QCD nucleon-nucleon interaction (ab-initio Models) R. Krücken - XVth UK Postgraduate School in Nuclear Physics – Lecture 1

4. Ab-initio calculations of light nuclei 7500 CPU hours R. Krücken - XVth UK Postgraduate School in Nuclear Physics – Lecture 1

5. From QCD to atomic nuclei d u u Protons, Neutrons Quarks, Gluons Light nuclei (A10) ? ? QCD Heavy nuclei nucleon-nucleon interaction (ab-initio Models) effective nucleon-nucleon interaction (Mean-field theories) R. Krücken - XVth UK Postgraduate School in Nuclear Physics – Lecture 1

6. The Nuclear Landscape Source: NUCLEUS A Trip Into The Heart of Matter R. Krücken - XVth UK Postgraduate School in Nuclear Physics – Lecture 1

7. Semi-empirical mass formula Volume energy R = r0A1/3 Binding Energy Coulomb energy Surface energy Asymmetry energy Pairing energy Bethe and von Weizäcker-1935 Volume 15 Volume + Surface Volume + Surface + Coulomb 10 Coefficients av = 15.56 MeV as = 17.23 MeV ac = 0.697 MeV aA = 23.285 Mev aP = 12.0 MeV B/A (MeV/nucleon) Volume + Surface + Coulomb + Asymmetry 5 50 100 150 200 250 Mass number A R. Krücken - XVth UK Postgraduate School in Nuclear Physics – Lecture 1

8. Binding energy per nucleon • Maximal binding around Fe • Synthesis up to Fe via fusion in stars • heavy elements are produced differently (n-capture) • Fission and alpha decay are possible Saturation of binding due to short range of NN interaction R. Krücken - XVth UK Postgraduate School in Nuclear Physics – Lecture 1

9. Shell effects in the binding energies ? Mexp – MWeizsäcker ? R. Krücken - XVth UK Postgraduate School in Nuclear Physics – Lecture 1

10. Shell structure in nucleiandmetalclusters 198 184 168 138 126 112 92 82 70 58 50 40 40 28 20 20 20 8 8 8 2 2 2 H.O. + L2 + L•S S.G. Frauendorf, C. Guet Annu. Rev. Nucl. Part. Sci. 2001 , Vol. 51: 219-259. R. Krücken - XVth UK Postgraduate School in Nuclear Physics – Lecture 1

11. Central Questions in Nuclear Structure Physics • Where are the limits of nuclear stability? • How does shell structure change far from stability? • What are the phases, relevant degrees of freedom, and symmetries of the nuclear many-body system? • Are there new modes of collective excitation? • How are the Heavy Elements produced? • Unified theoretical framework • with predictive power Diversified experimental strategy to understand the Structure and Dynamics of Exotic Nuclei: • Measure Ground State Properties • Gamma-ray spectroscopy of excited states • Reaction studies R. Krücken - XVth UK Postgraduate School in Nuclear Physics – Lecture 1

12. Valley ofstability & thelimitsofstability Energy R. Krücken - XVth UK Postgraduate School in Nuclear Physics – Lecture 1

13. r-process and shell structure CS22892-052 (Sneden et al. 2003) solar r abundance log(X/H)-12 element number • Nuclear shell structure • Defines r-process path • Imprinted in abundance pattern • maybe modified for exotic nuclei Pfeiffer et al. r - process • Fission may fill the holes • Depends on shell structure G. Martinez-Pinedo et al. R. Krücken - XVth UK Postgraduate School in Nuclear Physics – Lecture 1

14. Production of radioactive ion beams R. Krücken - XVth UK Postgraduate School in Nuclear Physics – Lecture 1

15. How to produce and study Exotic Nuclei • Production of radioactive ion beams: • in-flightproduction • Isotope Separation On-Line • What can be measured? • existence of nuclei • masses, radii, half-lives • Excited states: energies, quantum numbers, transition matrix elements , lifetimes, moments, single-particle occupations ... • Spectroscopic Methods: • g- ray and particle spectroscopy following • Decay spectroscopy • Coulomb excitation • One- and Multi-nucleon transfer • knockout-reactions • Secondary fragmentation R. Krücken - XVth UK Postgraduate School in Nuclear Physics – Lecture 1

16. Production of radioactive ion beams In-flightseparation Isotope Separation On-Line Exotic nuclei are produced in thin target as fragment of heavy beam Reaction induced by light projectile (p,d,n) in thick target • Diffusion from thick target • depends on chemistry • - Needs time Fragments move with beam velocity (30-90% c) R. Krücken - XVth UK Postgraduate School in Nuclear Physics – Lecture 1

17. In-flight production of radioactive beams Projectile fragmentation or fission at high energies (50 -1000 AMeV) Both fragments are highly excited ad evaporate nucleons Fig. by T. Glasmacher (NSCL/MSU) R. Krücken - XVth UK Postgraduate School in Nuclear Physics – Lecture 1

18. Br - DE - Br Separation Method R. Krücken - XVth UK Postgraduate School in Nuclear Physics – Lecture 1

19. Fragment Identification DE DE TOF SIS FRS UNILAC ESR 100 m R. Krücken - XVth UK Postgraduate School in Nuclear Physics – Lecture 1

20. FAIR: Facility for Antiproton and Ion Research Primary Beams • 1012/s; 1.5-2 GeV/u; 238U28+ • Factor 100-1000 over present in intensity Secondary Beams Storage and Cooler Rings • Broad range of radioactive beams • up to 1.5 - 2 GeV/u; • up to factor 10 000 in intensity over present • Antiprotons 3 - 30 GeV • Radioactive beams • e- - A and Antiproton-A collider Future Facility SIS 100/300 GSI today SIS 18 UNILAC ESR 100 m HESR Super FRS RESR CR NESR R. Krücken - XVth UK Postgraduate School in Nuclear Physics – Lecture 1

21. ISOLDE at CERN 1.4 GeV from PS Booster R. Krücken - XVth UK Postgraduate School in Nuclear Physics – Lecture 1

22. REX-ISOLDE R. Krücken - XVth UK Postgraduate School in Nuclear Physics – Lecture 1

23. FRIB in the U.S. (MSU/NSCL) R. Krücken - XVth UK Postgraduate School in Nuclear Physics – Lecture 1

24. Modifications of nuclear shell structure R. Krücken - XVth UK Postgraduate School in Nuclear Physics – Lecture 1

25. Two-neutron separation energies Shell closure Fig. by R.F. Casten R. Krücken - XVth UK Postgraduate School in Nuclear Physics – Lecture 1

26. The extreme single-particle model Strong Spin-orbit From individual nuclei with NN interaction to mean field with residual interaction R. Krücken - XVth UK Postgraduate School in Nuclear Physics – Lecture 1

27. Ingredients: Homogeneous vertical magnetic field Radial trapping cyclotron motion: wc= B q/m Axial electrostatic quadrupole field Vertical trapping Vertical oscillation: wz=(qU0/(md2))1/2 Penning Trap MassMeasurements 4d2=(2z02+r02) • modifiedcyclotronmotion: • magnetronfrequency: R. Krücken - XVth UK Postgraduate School in Nuclear Physics – Lecture 1

28. Penning Trap MassMeasurements Excite cyclotron motion via quadrupole RF Coupling between modes  conversion to cyclotron motion Eject ions along trap axis  transform radial energy to axial energy via dB/dz gradient Measure time of flight (TOF) -the shorter TOF, the closer is the excitation frequency to the resonance K. Blaum, Physics Reports 425 (2006) 1 – 78 R. Krücken - XVth UK Postgraduate School in Nuclear Physics – Lecture 1

29. ISOLTRAP measurement purification bunching A. Herlert, et al., Int. J. Mass Spectrom. 251, (2006) 131 R. Krücken - XVth UK Postgraduate School in Nuclear Physics – Lecture 1