Physics with Exotic Nuclei. Hans-Jürgen Wollersheim

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1 Physics with Exotic Nuclei Hans-Jürgen Wollersheim

2 Outline Scattering Experiments with RIBs Nuclear Structure Results Experimental evidence for closed-shell nuclei Scattering experiments at relativistic energies Projectile-like identification (Z, A) and scattering angle θ Doppler-shift correction of the emitted γ-rays

3 Physics with Exotic Nuclei Experimental evidence for magic numbers close to stability Maria Goeppert-Mayer & J. Hans D. Jensen + E 1 B( E; )

4 Physics with Exotic Nuclei Experimental evidence for magic numbers close to stability E + 1 Nuclei with magic numbers of neutrons/protons high energy of 1 + state low B(E; ) values transition probability measured in single particle units (spu) B( E; ) If we move away from stability?

5 Production, Separation, Identification SIS projectile projectile fragment FRS target nucleus abrasion ablation FRagment Separator Standard FRS detectors TPC-x,y S,S4 Plastic scintillator S4 MUSIC S4

6 Scattering Experiment at Relativistic Energies 104 Sn, 100 MeV/u 14 Xe, 793MeV/u new digital readout standard scintillator (SC1) finger segmented detector 104 Sn fragments using 14 Xe at 793 MeV/u high rate at S ~10 6 s -1 ~400 % more tracking efficiency good A/Q resolving power Frederic Ameil

7 Scattering Experiment at Relativistic Energies impact parameter: b D min fragment Au Rutherford scattering only if distance of closest approach D min is large compared to nuclear radii + surfaces: > CP + CT 5 Dmin + C P, C T half-density radii fm E 13.3MeV B( E1;0 1 E = MeV B( E;0 ) 0.55e b + ) = 9Wu E =.615 MeV σ πλ Z Pe c π e b λ B ( πλ;0 λ) 1 ( λ 1) ln( b / b) a for for λ λ = 1 B( E3;0 3 ) = 34Wu

8 Atomic Background Radiation Radiative electron capture (REC) capture of target electrons into bound states of the projectile: σ ~ Primary Bremsstrahlung (PB) capture of target electrons into continuum states of the projectile: σ ~ Secondary Bremsstrahlung (SB) Stopping of high energy electrons in the target: σ Z p Z t Z p Z t ~ Z p Zt Bremsstrahlung: slowing down of a moving point-charge

9 Scattering Experiment at Relativistic Energies 104 Sn 197 Au-target 14 Xe, 793MeV/u relativistic Coulomb excitation xy position from LYCCA

10 Scattering Experiment at Relativistic Energies 104 Sn 14 Xe, 793MeV/u Lund-York-Cologne CAlorimeter secondary 197 Au target DSSSD (x,y,δe) diamond/plastic DSSSD (x,y,δe) exp. observables: Z, A, θ RIB from FRS CsI CsI time-of-flight

11 Scattering Experiment at Relativistic Energies secondary 9 Be target DSSSD (x,y,δe) diamond/plastic DSSSD (x,y,δe) exp. observables: Z, A, θ RIB from FRS CsI CsI time-of-flight

12 Scattering Experiment at Relativistic Energies m c E = kin γ 1 with and E kin γ = = E 1 CsI 1 + E ( v ) c DSSSD with v from LYCCA-ToF secondary 9 Be target DSSSD (x,y,δe) diamond/plastic DSSSD (x,y,δe) exp. observables: Z, A, θ RIB from FRS CsI CsI time-of-flight

13 Lund-York-Cologne CAlorimeter DSSSD start ToF Au target PreSPEC target chamber variable target position (13cm, 3cm) Pavel Golubev

14 Additional γ-ray Background Radiation Coulomb excitation: A/Q - 37 Ca all Ca detected in ΔE-E prompt ΔE-E 1 interaction target most γ-rays from CATE HECTOR BaF 37 Ca beam at 196 MeV/u Fragmentation: A/Q - 37 Ca K detected (mainly 36 K) prompt time spectrum

15 Scattering Experiment at Relativistic Energies 80 Kr 197 Au, 150 AMeV Doppler effect E γ 0 E γ 1 β cosϑγ = 1 β ab

16 Scattering Experiment at Relativistic Energies Doppler effect: E γ 0 E γ 1 β cosϑγ = 1 β ab for ϑ p 0 0 Lorentz boost: dω dω rest lab E γ = E γ 0 beam

17 Doppler-Shift Correction 38 U on 197 Au (386 mg/cm ) at 183 AMeV Au cos θ γ Au K α Au K α Au K α Au K β Au K β Au K β Michael Reese

18 Doppler-Shift Correction 38 U on 197 Au (386 mg/cm ) at 183 AMeV 38 9U E γ 0 = E γ 1 β cosϑγ 1 β ab cos θ γ U K α U K α U K α U K β U K β U K β Michael Reese

19 Doppler Broadening = γ γ γ γ ϑ β ϑ β cos 1 sin 0 0 E E ϑ γ ( ) ( ) = γ γ γ γ ϑ β β ϑ β cos 1 1 cos 0 0 E E β opening angle: slowing down in target:

20 γ-ray set-up with higher efficiency target beam Ivan Kojouharov

21 Advanced GAmma Tracking Array Encapsulation Signals from 36 segments + core are measured as a function of time (γ-ray interaction point) John Strachan

22 Au, Be target LYCCA AGATA Cluster array HECTOR BaF array

23 HECTOR team

24 AGATA at PreSPEC preprocessor computer farm AGATA digitiser Damian Ralet, Stephane Pietri

25 High-energy Coulomb excitation triaxiality in even-even nuclei (N=76) First observation of a second excited + state populated in a Coulomb experiment at 100 AMeV using EUROBALL and MINIBALL Ge-detectors. shape symmetry collective strength 0 sin (3γ ) B( E; 1) 7 9 8sin (3γ ) = B( E;1 0) 3 sin (3γ ) sin (3γ ) 1 B( E; 0) = B( E;1 0) 1+ 3 sin (3γ ) 9 8sin (3γ ) 3 sin (3γ ) 9 8sin (3γ ) E () sin 3γ = E () sin 3γ T.R. Saito et al. Phys.Lett. B669 (008), 19

26 Ivan Kojouharov, Michael Reese, Namita Goel, Liliana Cortes, Frederic Ameil, Bogdan Szczepanczyk H.-J. W., Damian Ralet, Pushpendra Singh, Stephane Pietri, Tobias Habermann, Edana Merchan, Giulia Guastalla, Plamen Boutachkov, Adolf Brünle, Ian Burrows, Jonathan Strachan, (Paul Morral), Jürgen Gerl, (Henning Schaffner, Magda Gorska)

27 Slowed down beams new experimental perspectives collective strength nuclear shape angular momentum transfer: Z e Q 4 v a P 0 Lmax ( 1 cosθcm ) V C

28 Slowed down beams beam characteristics 10 9 pps 10 7 pps pps 10 5 pps 64 Ni 700 AMeV 6 Co ~ 13 AMeV ΔEnergy 5. AMeV Δθ 35 mrad

29 Slowed down beams experimental set-up degrader target TPC-1 TPC- SC41 (x 1 y 1 t 1 ) (x y t ) (x 3 y 3 t 3 ) E / A t =.78 1 / ( E A ) s 3/ 1 s 1 electrostatic mirror + MCP detector position resolution ~ 1 mm time resolution ~ 100 ps experimental results: velocity β beam energy E/A 1 scattering angle θ cm

30 Slowed down beams experimental set-up degrader target TPC-1 TPC- SC41 (x 1 y 1 t 1 ) (x y t ) (x 3 y 3 t 3 ) TOF between MCP and DSSSD MCP DSSSD Time resolution 00 ps for one of the 56 detector pixels Akhil Jhingan (IUAC)

31 Reactions with Relativistic Radioactive Beams R 3 B Excitation energy E * from kinematically complete measurement of all outgoing particles EE = mm ii + mm ii mm jj γγ ii γγ jj 1 ββ ii ββ jj ccccccθθ iiii ii ii jj mm pppppppp cc + EE γγ,ssssss

32 Dipole strength distribution of 68 Ni mean field calculation Pygmy resonance neutron decay data direct γ-decay branching ratio: E.Litvinova et al.; PRC 79, (009) Γ 0 /Γ = 7()% γ-ray decay data O. Wieland et al.; Phys. Rev. Lett 10, 0950 (009) D. Rossi et al.; Phys. Rev. Lett 111, 4503 (013)