MP-41 Teil 2: Physik exotischer Kerne

1. MP-41 Teil 2: Physik exotischer Kerne 13.4. Einführung, Beschleuniger 20.4. Schwerionenreaktionen, Synthese superschwerer Kerne (SHE) 27.4. Kernspaltung und Produktion neutronenreicher Kerne 4.5. Fragmentation zur Erzeugung exotischer Kerne 11.5. Halo-Kerne, gebundener Betazerfall, 2-Protonenzerfall 18.5. Wechselwirkung mit Materie, Detektoren 25.5. Schalenmodell 1.6. Restwechselwirkung, Seniority 8.6. Tutorium-1 15.6. Tutorium-2 22.6. Vibrator, Rotator, Symmetrien 29.6. Schalenstruktur fernab der Stabilität 6.7. Tutorium-3 13.7. Klausur

2. Rare-Isotope Beam Experiments Discovery of projectile-fragmentation reaction at Bevalac @ LBL (Lawrence Berkeley Laboratory) D.E. Greiner et al., Phys.Rev. Lett. 35 (1975) 152 12C, 16O (2.1 AGeV) + Target (Be, C, Al, Cu, Ag, Pb) • Several fragments are produced in reactions • Velocity of fragments is almost the same as that of the beam • Momentum distribution is narrow, and has no significant correlation • with target mass and beam energies

3. Rare-Isotope Beam Experiments Momentum distribution of fragments (example 34S fragments from 40Ar + C @ 213 AMeV ) 34S fragments: 400 MeV/c narrow 40Ar beam: 26600 MeV/c Momentum distribution of fragments are represented by a simple formula based on the Goldhaber model A: Beam mass number F: Fragment mass number σ0= 90 MeV/c

4. Production of Radioactive Ion Beams Spallation Fragmentation ISOL = Isotope Separator On Line

5. In-flight separation of Rare Isotope Beams • Primary (production) target • Peripheral nuclear reactions • Forward focused products Secondary (reaction) target Experimental area Electromagnetic separator Selected radioactive beam E >> 20 AMeV Stable HI projectile source E ~ 1000 AMeV

6. Fragmentation at Relativistic Energies projectile projectile fragment target nucleus abrasion ablation FRS FRS FRagment Separator

7. RIBs produced by fragmentation or fission • 9Be target • exotic nuclei (also neutron deficient) • fragments nearly retain the projectile direction and velocity Interaction zone • 208Pb target, heavy beam (238U) • neutron rich nuclei • fragments can be faster than the projectile Coulomb field

8. Radioactive Ion Beams at GSI About 1000 nuclear residues identified 1GeV/u U + H A/Z-resolution ~10-3

9. The FRagment Separator FRS in-flight A and Z selection energy resolution: ~ 1 GeV 131Sn 132Sn

10. Rare Isotope Selection at FRS: Bρ – ΔE – Bρ selection fully striped fragments • Transmission : • 20-70 %for fragmentation • < 2 %for fission primary beam 86Kr ~700 AMeV 20m secondary beam 78Ni ~ 100 AMeV production target 9Be magnetic dipoles degrader magnetic dipoles Br µ bg A/Z DE µ Z2f(b) Br µ bg A/Z

11. FRagment Separator Beam & All Fragmentation Products Secondary Beam Primary Beam Spacial Dispersion Isotope Selection Momentum Selection Wedge-shaped Degrader 19Ne at 600AMeV: Phase-space imaging of differently shaped degraders within the achromatic ion-optical system. The results for a homogeneous, an achromatic, and a monoenergetic degrader are given. All degraders have the same thickness on the optical axis (d/r=0.5)

12. Fragment Separation40Ar 50MeV/u + Ta (100μm), wedge shaped Al (200μm) degrader 0.39 mrad 1.66mrad

13. Chromatic Aberration When different colors of light propagate at different speeds in a medium, the refractive index is wavelength dependent. This phenomenon is known as dispersion. Longitudinal (axial) chromatic aberration: Transverse (lateral) chromatic aberration: The focal planes of the various colors do The size of the image varies from one not coincide. color to the next.

14. Production, Separation, Identification SIS UNILAC FRS projectile projectile fragment target nucleus abrasion ablation FRagment Separator Standard FRS detectors TPC-x,yposition@ S2,S4 Plastic scintillator (TOF) @ S4 MUSIC (ΔE) @ S4

15. Standard FRS and RISING detectors Y Z X ToF A/Q DE Y E X productiontarget multiwire chamber; beam position reaction target scintillator MUSIC ionization chamber; Z CATE Si-CsI arrays; (X,Y), Z,A scintillator b Ge-Cluster detectors

16. Scattering experiments at relativistic energies xy position from LYCCA

17. Calculate the event-rate for the fragmentation reaction to produce the doubly magic nucleus 100Sn. The expected production cross section is 7.4·10-12 [barn]. 9g of 9Be ≡ 6.02·1023 particles/cm2 4g of 9Be ≡ 2.68·1023 particles/cm2 luminosity = projectile [s-1] · target nuclei [cm-2] = 1010 [s-1] · 2.7·1023 [cm-2] event rate = luminosity [s-1 cm-2] · cross section [cm2] = 2.7·1033 [s-1 cm-2] · 7.4·10-36 [cm2] = 0.02 [s-1] = 72 [h-1] = 1718 [d-1]