Collective modes investigated by inelastic scattering and charge-exchange reactions with magnetic spectrometers

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1 Collective modes investigated by inelastic scattering and charge-exchange reactions with magnetic spectrometers Muhsin N. Harakeh Kernfysisch Versneller Instituut 4 th CNS International Summer School (CISS05) CISS05, August 2005; Wako, Tokyo, Japan 1

2 Outline Introduction on Giant Resonances (GRs) What are GRs? Why study GRs? Isoscalar giant resonances; compression modes Inelastic α-scattering ISGMR, ISGDR Isovector charge-exchange modes ( 3 He,t) & (d, 2 He) charge-exchange reactions GTR, IVSGMR, IVSGDR; GT + Strength Outlook CISS05, August 2005; Wako, Tokyo, Japan 2 2

3 (d, 2 He) 85 MeV/u ( 3 He,t) 60 MeV/u (t, 3 He) 43 MeV/u focal plane detectors dipole magnets target triton beam S800@NSCL 3 He ++ (t, 3 He) 115 MeV/u TRIUMF (n,p) (π-cex) IUCF (p,n) ( 3 He,t) K600 ithemba (p,p) K600 Texas A&M etc Grand Raiden@ RCNP ( 3 He,t) 140 MeV/u Also done (p,n) (n,p) 300 MeV CISS05, August 2005; Wako, Tokyo, Japan 3 3

4 SHARAQ Spectrometer Parameters Spectroscopy of HAdron systems with RadioActive Quantum beams Momentum resolution p/p < 1/15000 δe x ~300 kev for A=8, E=300MeV/u Maximum rigidity Bρ = 6.8Tm (ρ =4.8m) Solid angle Ω=12 msr Momentum acceptance +/- 3% High-quality RI beam-line Dispersion matching QQDQD (SC) (NC) Total length 19 m Total weight > 400t CISS05, August 2005; Wako, Tokyo, Japan 4 4

5 Giant resonances: fundamental highfrequency modes of nuclear excitation Interesting to study on own merit: E x, Γ, %EWSR; Microscopic structure compare to theory: HF+RPA; RMFT, RRPA, etc. Effective interactions, medium effects (meson-coupling constants); IVSGDR 0 - strength (pion quantum numbers) Moreover, Equation of state (EOS) ISGMR, ISGDR Incompressibility, symmetry energy K A = K vol + K surf A -1/3 + K sym ((N-Z)/A) 2 +K Coul Z 2 A -4/3 CISS05, August 2005; Wako, Tokyo, Japan 5 5

6 IVGDR, IVSGDR, IVGMR n-skin thickness; isospin mixing Collective-flow in H.I. collisions Astrophysics: Input for supernova explosions, neutron stars Microscopic picture: GRs are coherent (1p-1h) excitations induced by single-particle operators. Excitation energy depends on i) multipole L (Lħω, except for isoscalar monopole and isoscalar dipole GRs, 2ħω & 3ħω, respectively), ii) strength of effective interaction and iii) collectivity. Exhaust appreciable % of EWSR and/or NEWSR Acquire a width due to coupling to continuum and to underlying 2p-2h configurations. CISS05, August 2005; Wako, Tokyo, Japan 6 6

7 Nucleus Many-body system with a finite size Vibrations S=0, T=0 Multipole expansion with r, Y lm, τ, σ S=0, T=1 S=0, T=1 S=1, T=1 S=1, T=1 L=0: Monopole ISGMR IAS IVGMR GTR IVSGMR L=1: Dipole L=2: Quadrupole r 2 Y 0 τy 0 τ r 2 Y 0 τ σ Y 0 τ σ r 2 Y 0 ISGDR r 3 Y 1 ISGQR IVGDR IVSGDR τ ry 1 τσ ry 1 IVGQR IVSGQR r 2 Y 2 τ r 2 Y 2 τσ r 2 Y 2 L=3: Octupole LEOR, HEOR r 3 Y 3 CISS05, August 2005; Wako, Tokyo, Japan 7 7

8 Isoscalar Excitation Modes of Nuclei Giant Resonance: Coherent vibration of nucleons in a nucleus. Compression modes : ISGMR, ISGDR E ISGMR = h m K A 2 r E ISGDR 27 K 7 A + ε F = h m r The nucleus incompressibility: K A =[r 2 (d 2 (E/A)/dr 2 )] r =R0 CISS05, August 2005; Wako, Tokyo, Japan 8 8

9 In HF+RPA calculations, K nm d = 9 ρ E A ρ= ρ 2 2 ( / ) 2 dρ 0 Nuclear matter E/A: binding energy per nucleon K A : incompressibity : nuclear density energy ε F : Fermi 0 : nuclear density at saturation 208 Pb K A is obtained from excitation energy of ISGMR & ISGDR K A =0.64K nm J.P. Blaizot, NPA591 (1995) 435 CISS05, August 2005; Wako, Tokyo, Japan 9 9

10 CISS05, August 2005; Wako, Tokyo, Japan 10 10

11 HF+RPA; ISGDR in 208 Pb I. Hamamoto el al. J. Pikarewicz G. Colo et al. D. Vretenar et al. CISS05, August 2005; Wako, Tokyo, Japan 11 11

12 ISGQR, ISGMR, ISGDR KVI (1977) TAMU(2000) E α =240 MeV Large instrumental background! 208 Pb(α,α ) at E α =120 MeV CISS05, August 2005; Wako, Tokyo, Japan 12 12

13 dσ/d Ω (mb/sr) Pb(α,α ) E α = 386 MeV E x = 14.5 MeV L=0, T=0 L=1, T=0 L=2, T=0 L=3, T=0 ISGMR, ISGDR ISGQR, HEOR 100 % EWSR At E x = 14.5 MeV θ cm. (degree) CISS05, August 2005; Wako, Tokyo, Japan 13 13

14 Uchida et al., RCNP (α,α ) spectra at 386 MeV 116 Sn ISGDR ISGDR ISGMR ISGMR MDA results for L=0 and L=1 ISGDR ISGDR ISGMR ISGMR CISS05, August 2005; Wako, Tokyo, Japan 14 14

15 15 15 CISS05, August 2005; Wako, Tokyo, Japan Multipole decomposition analysis (MDA) fraction EWSR : ) ( section) cross (unit section cross DWBA : ), ( section cross l Exprimenta :. ), ( ), ( ) (. ), ( E a calc L E de d d ex E de d d calc L E de d d E a ex E de d d L m c m c m c L L m c Ω Ω Ω = Ω ϑ σ ϑ σ ϑ σ ϑ σ a. ISGR (L<15)+ IVGDR (through Coulomb excitation) b. DWBA formalism; single folding transition potential ) ' ( )) ' ( ', ( ' ) ( ) ' ( )) ' ( ', ( ) ' ( )) ' ( ', ( )[, ' ( ' ), ( r r r r V d r r U r r r r V r r r r V E r d r E r U L ρ ρ ρ ρ ρ ρ δρ δ = + =

16 16 16 CISS05, August 2005; Wako, Tokyo, Japan Transition density ISGMR Satchler, Nucl, Phys, A472 (1987) 215 ISGDR Harakeh & Dieperink, Phys. Rev. C23 (1981) 2329 Other modes Bohr-Mottelson (BM) model ) 10 3) / (25 (11 6 ) ( )] 4 ( [3 3 ), ( > < > < > < = + + > < + + = r r r R mae r dr d dr d r dr d r r dr d r R E r ε π β ρ ε β δρ h E r ma r dr d r E r > < = + = ) ( ] [3 ), ( πh α ρ α δρ ) 2 ( 1 ) 2 ( ) ( ) ( ), ( > < > < + + = = = l l L L L L r r mae l l l c r dr d E r π h β δ ρ δ δρ ħ 2 ħ 2 ħ 2

17 Results of ISGMR/ISGDR E GMR (MeV) Γ (MeV) EWSR (%) E LEGDR (MeV) Γ (MeV) EWSR (%) E HEGDR (MeV) Γ (MeV) EWSR (%) 90 Zr (0.1) (0.2) (3) (0.5) (1.2) (2.9) (0.7) (1.5) (8) 116 Sn (0.1) (0.3) (4) (0.5) (1.) (2.2) (0.5) (2.3) (9) 144 Sm 15.3 (0.1) 3.71 (0.12) 84 (4,-25) 14.2 (0.2) 4.8 (0.8) 23 (4,-10) 25.0 (1.7) 19.9 (1.4) 91 (25,-17) 208 Pb (0.2) (0.4) (9) (0.1) (0.4) (0.4) (0.3) (0.4) (6) E is about 0.1 MeV CISS05, August 2005; Wako, Tokyo, Japan 17 17

18 L=0 Breit-Wigner shape: E m (MeV) 112 Sn m 0.1 (MeV) Sn Sn Sn Sn Sn Sn ,114,118,120,122,124 Sn: this work 116 Sn: Uchida et al. CISS05, August 2005; Wako, Tokyo, Japan 18 18

19 ISGMR energy E ISGMR CISS05, August 2005; Wako, Tokyo, Japan 19 19

20 208 Pb E ISGDR (MeV) E ISGMR (MeV) K nm (MeV) HE LE Uchida et al. (Breit-Wigner) 22.8 (0.3) 13.0 (0.2) 13.5 (0.2) Morsch et al (0.8) 13.8 Djalali et al (0.2) 13.9 Adams et al (0.2) Davis et al. 22.4(0.5) Clark et al. 19.9(0.8) 12.2(0.6) 14.17(0.28) Hamamoto et al ~ Colo et al. 23.9(22.9 *) Piekarewicz et al ~ Vretenar et al Shlomo and Sanzhur ~25.0 ~ Gorelik and Urin * Including the effect of 2p-2h coupling CISS05, August 2005; Wako, Tokyo, Japan 20 20

21 Decay of giant resonances Width of resonance,, (, ) : direct or escape width : spreading width : pre-equilibrium, : compound Decay measurements Direct reflection of damping processes Allows detailed comparison with theoretical calculations CISS05, August 2005; Wako, Tokyo, Japan 21 21

22 Decay and microscopic structure of ISGDR Transition operator Ο = + + L= 1 ry 1 r 3 Y 1.. i 0 i 0 i i spurious center of mass motion overtone 3 ħ excitation (overtone of c.o.m. motion) CISS05, August 2005; Wako, Tokyo, Japan 22 22

23 AGOR cyclotron K = 600 light and heavy ions p < 190 MeV q/a = ½ ; E/A < 90 MeV CISS05, August 2005; Wako, Tokyo, Japan 23 23

24 Equipment Big momentum Bite magnetic Spectrometer (BBS) its associated Focal-Plane Detectors (ESN) various coincidence detectors neutrons (EDEN), protons (SiLi-ball), γ s (GeLi, Clover), phoswich detectors readout electronics DSP, VME, FERA CISS05, August 2005; Wako, Tokyo, Japan 24 24

25 CISS05, August 2005; Wako, Tokyo, Japan 25 25

26 Si-ball 16 Si-detectors at 10 cm from the target total solid angle: 1 sr acceptance: deg coverage: 9.2 msr momentum bite: 19 % dispersion 2.54 cm/% total solid angle: 0.37 sr KVI Big-Bite Spectrometer (BBS) CISS05, August 2005; Wako, Tokyo, Japan 26 26

27 Setup: ESN detector Focal-Plane Detector: (FPDS): 2 VDCs Focal-Plane Polarimeter: (FPP): 4 MWPCs & graphite analyzer M. Hagemann et al., NIM A 437 (1999) 459 V.M. Hannen et al., NIM A 500 (2003) 68 features a.o.: fast readout VDC readout pipeline TDCs VDC decoding using imaging techniques DSP based online analysis Bari, Darmstadt, Gent, Iserlohn, KVI, Milano, Münster, TRIUMF CISS05, August 2005; Wako, Tokyo, Japan 27 27

28 Excitation of ISGDR in 208 Pb In 208 Pb located around 22 MeV and width of 4 MeV L=1 angular distribution peaks close to a scattering angle of 0 o Difficult to identify in nuclear continuum and rides on instrumental background 1.5 o < θ BBS < 5.0 o Singles 208 Pb(α,α ) 200 MeV continuum? CISS05, August 2005; Wako, Tokyo, Japan 28 28

29 ISGDR L = 1 CISS05, August 2005; Wako, Tokyo, Japan 29 29

30 statistical decay p decay n decay hole states (α,α ) CISS05, August 2005; Wako, Tokyo, Japan 30 30

31 Proton-decay detection α-p separation using rise time of signal SiLi α p CISS05, August 2005; Wako, Tokyo, Japan 31 31

32 Neutron-decay detection CISS05, August 2005; Wako, Tokyo, Japan 32 32

33 208 Pb(α,α p or n) E n (MeV) n decay E p (MeV) hole states p decay hole states E x (MeV) Efs (MeV) E x (MeV) CISS05, August 2005; Wako, Tokyo, Japan 33 33

34 208 Pb(α,α ) followed by n decay counts / 0.4 MeV decay from ISGDR decay from continuum hole states statistical E x in 207 Pb (MeV) CISS05, August 2005; Wako, Tokyo, Japan 34 34

35 Statistical decay Direct decay d 2 /d de x (mb sr -1 MeV -1 ) d 2 /d de x (mb sr -1 MeV -1 ) E x in 208 Pb (MeV) E x in 208 Pb (MeV) CISS05, August 2005; Wako, Tokyo, Japan 35 35

36 208 Pb(α,α ) followed by p decay Decay to hole states in 207 Tl; branching ratios predicted by Gorelik et al. CISS05, August 2005; Wako, Tokyo, Japan 36 36

37 Branching ratios for decay CISS05, August 2005; Wako, Tokyo, Japan 37 37

38 ISGDR in 208 Pb in p decay E x = 22.1 ± 0.3 MeV L = 1 transition gated on hole states CISS05, August 2005; Wako, Tokyo, Japan 38 38

39 Branching ratios for decay ` 2.4 ` ` 1.2 This work Gorelik et al PRC 62 (2000) CISS05, August 2005; Wako, Tokyo, Japan 39 39

40 Present Status 1 Djalali et al., Morsch et al., Adams et al., Davis et al., Clark et al., Uchida et al., Uchida et al., this work p 9 this work n E x = MeV E x ISGDR (MeV) /7 8/9 year CISS05, August 2005; Wako, Tokyo, Japan 40 40

Overtone of the ISGQR? [r 4 Y 2 ] E x = 26.9 0.7 MeV Muraviev and Urin Bull. Acad. Sci.

41 Overtone of the ISGQR? [r 4 Y 2 ] E x = MeV Muraviev and Urin Bull. Acad. Sci. USSR Phys. Ser. 52 (1988) 123 E x = 28.3 MeV CISS05, August 2005; Wako, Tokyo, Japan 41 41

42 Conclusions! There has been much progress in understanding ISGMR & ISGDR Systematics: E x, Γ, %EWSR K nm 220 MeV Microscopic Structure for a few nuclei Observation of a new excitation that could be the quadrupole compressional mode, i.e. overtone of ISGQR CISS05, August 2005; Wako, Tokyo, Japan 42 42

43 Spin-isospin excitations n p L=0 S=1 T=1 GTR Gamow-Teller transitions; Isospin ( T=1) Spin ( S=1) Advantages Cross section peak at θ=0 deg. ( L=0) Strong excitation of GT states at E/A= MeV/u CISS05, August 2005; Wako, Tokyo, Japan 43 43

44 ( 3 He,t) Reaction above 150 MeV/u Energy dependence of effective interactions MeV/A V 0 part: Minimum. V (MeV fm 3 ) V c 0 V c στ V σt part: Relatively large. 100 V c τ V t part: Minimum. 0 V c σ E (MeV) CISS05, August 2005; Wako, Tokyo, Japan 44 44

45 Charge-exchange probes (p,n)-type ( T z = 1) (n,p)-type ( T z = +1) β -decay (p,n) ( 3 He,t) heavy ion (π +,π 0 ) β + -decay (n,p) (d, 2 He) (t, 3 He) heavy ion ( 7 Li, 7 Be) (π -,π 0 ) Energy per nucleon (>100 MeV/n) Spin-flip vs non-spin-flip Complexity of reaction mechanism Experimental considerations CISS05, August 2005; Wako, Tokyo, Japan 45 45

46 Nuclear Classics: spin-flip & GT transitions GT T 0 +1 GT T 0 GT T 0-1 GT - ( 3 He,t), (p,n) GS T 0-1 (N-1, Z+1) S=1 M1 M1 T 0 +1 T 0 (e,e ), (p,p ) 0 + GS T 0 (N, Z) difficult! GT T 0 +1 GS T 0 +1 (N+1, Z-1) 1 + GT + (n,p), (d, 2 He), (t, 3 He) CISS05, August 2005; Wako, Tokyo, Japan 46 46

47 p n Isovector giant monopole resonances n p n p L=0 S=0 T=0 ISGMR L=0 S=0 T=1 IVGMR L=0 S=1 T=1 IVSGMR O=r λ [σ Υ L ] J τ IAS: λ=0 S=0 L=0 J=0 GTR: λ=0 S=1 L=0 J=1 IVGMR: λ=2 S=0 L=0 J=0 IVSGMR: λ=2 S=1 L=0 J=1 IVSGDR: λ=1 S=1 L=1 J=0,1,2 CISS05, August 2005; Wako, Tokyo, Japan 47 47

48 Successful: Decay studies GTR, IVSGDR in 208 Pb( 3 He,t+p) at 450 MeV (Akimune et al.) IVGMR/IVSGMR in Pb( 3 He,t+p) at 177 MeV at KVI & 410 MeV at RCNP (Zegers et al.) Unsuccessful: IVGMR/IVSGMR 124 Sn( 3 He,t+n) at 200 MeV at IUCF p EXCITATION PROTON p DIRECT DECAY SEMI DIRECT (PROTON) n n NEUTRON p STATISTICAL n DECAY CISS05, August 2005; Wako, Tokyo, Japan 48 48

49 Microscopic Structure of GTR and IVSGDR in 208 Bi Proton decay of 208 Bi: Direct decay dominant E x > E th (n) > E th (p) High Coulomb Barrier (Z=83) Statistical proton decay negligible. Angular correlations For IAS and GTR decay isotropic L=0 For IVSGDR anisotropic but not strongly Direct decay is influenced by: Low n-decay threshold High Coulomb barrier. CISS05, August 2005; Wako, Tokyo, Japan 49 49

50 Γ GTR /Γ << Γ IAS /Γ 0.5 IAS n-decay: isospin forbidden. Centroid energy shift: cut off by Coulomb barrier Γ IVSGDR /Γ > Γ GTR /Γ Higher proton energy Width Γ: Γ = Γ + Γ Escape: Direct decay Spreading: Statistical Decay Γ = Γ p = Σ Γ pi i Γ pi d 2 σ pi /(dω t dω p )dω p = Γ dσ/dω t Partial Escape Width Branching ratio CISS05, August 2005; Wako, Tokyo, Japan 50 50

51 Measurement of IVSGMR via 208 Pb( 3 He,t+p) d /d (mb/sr) gate I SDR+GDR IVSMR gate II cm (deg) maximum IVGQR IVGMR d /d ( cm =0 ) (mb/sr) IVSMR E x ~38 MeV =10 MeV E x ( 208 Bi) (MeV) DW81 (Raynal) Effective 3 He-N potential V = MeV (IAS) V = MeV (known ratio to V ) V T =-2.0 MeV/fm 2 most coherent 1p-1h wavefunction (normal Pb( He,t) Bi(IAS) modes) DW81 V = Use difference-of-angle to identify the monopole excitations d /d (mb/sr) cm (mrad) CISS05, August 2005; Wako, Tokyo, Japan 51 51

52 Continuum suppression Physical background (continuum) due to: breakup-pickup reactions quasifree knock-on reactions IVSGMR is wide (~10 MeV) and lying on top of the continuum. BASIC IDEA PROTON NEUTRON QUASIFREE MONOPOLE OUTGOING TRITON TARGET Continuum has a very flat angular distribution at forward angles SILICON/ SCINTILLATOR DETECTORS 3 HE BEAM CISS05, August 2005; Wako, Tokyo, Japan 52 52

53 Experiment RCNP facility K=400 MeV ring cyclotron Grand Raiden spectrometer Beam: 3 He ++, 450 MeV Target: 208 Pb foil M. Fujiwara et al., NIM A 422 (1999) 484 CISS05, August 2005; Wako, Tokyo, Japan 53 53

54 Experimental Considerations Over-focus mode for Grand-Raiden (H. Fujita et al. NIM A469, 55) refined to get: Vertical angle resolution: 0.4 o FWHM Horizontal angle resolution: 0.2 o FWHM Negligible systematic errors Sieve-slit is used for calibrations Θ ver (mrad) phi vs theta Θ hor (mrad) CISS05, August 2005; Wako, Tokyo, Japan 54 54

Experiment: 410 MeV 3 He-beam @ Grand Raiden @ RCNP RCNP Measure both t-singles and t-p coincidences.

55 Experiment: 410 MeV 3 Grand RCNP RCNP Measure both t-singles and t-p coincidences. 3 H 3 He 8 E-E telescopes 4@113 o 4@136 o 5 mm 5 mm p CISS05, August 2005; Wako, Tokyo, Japan 55 55

56 Set-up of the Proton Counter Si(Li) detectors with a thickness of 5 mm, covering a solid angle of 5.7% in total. 35 kev ( 241 Am test) CISS05, August 2005; Wako, Tokyo, Japan 56 56

57 Spin-isospin-flip transitions in charge-exchange reactions and proton decay A. Krasznahorkay et al., PRC 64 (2001) A. Krasznahorkay et al., PRL 82 (1999) H. Akimune et al., PRC 52 (1995) 604. H. Akimune et al., Phys. Lett. B 233 (1994) 107 ( 3 He,t) reactions E( 3 He)=450 MeV ( 3 He,tp) Coincidence data CISS05, August 2005; Wako, Tokyo, Japan 57 57

58 Experimental Results and Theoretical Calculations Partial escape width for GTR Theory This work channel E x (kev) Γ i (kev) branch (%) Γi (kev) branch (%) 1/2 5/2 3/2 3/2 13/2 7/2 9/2 Total Partial escape width for IVSGDR Theory This work channel E x (kev) Γi (kev) branch (%) Γi (kev) branch (%) 1/2 ± 5/2 3/2 13/2 /2 9/2 Theory: E. Moukhai, V.A. Rodin, M.H. Urin Continuum RPA CISS05, August 2005; Wako, Tokyo, Japan 58 58

59 Summary: 208 Pb( 3 He,tp) GTR: Γ /Γ~4.9%, Γ =184±49 kev Small branching ratio: Spreading effect is very important. Coupling to underlying 2p-2h states. Centroid energy shift caused by High Coulomb barrier. IVSGDR: Γ /Γ~14.1%, Γ = 1180±340 kev Larger p-decay Γ /Γ compared to GTR. E p : enough higher than Coulomb barrier, centrifugal barrier. Enhancement of decay to high-spin 1n-hole states CISS05, August 2005; Wako, Tokyo, Japan 59 59

60 Results d 2 /d de x (mb/srmev) d 2 /d de x (mb/srmev) IAS GTR SDR IVSGMR Pb( He,t) E( 3 He)=410 MeV cm=0.57 cm= E x ( 208 Bi) (MeV) GTR t singles IAS 15 SDR E x ( 208 Bi) (MeV) R.G.T. Zegers et al., PRL 90 (2003) t-p coincidences d 3 /d t d p de x (mb/sr 2 MeV) IAS GTR Difference of angles IVSGMR continuum d 3 /d t d p de x (mb/sr 2 MeV) SDR IVSGMR Pb( He,tp) E( 3 He)=410 MeV cm=0.57 cm= E x ( 208 Bi) (MeV) IAS GTR IVSGMR SDR E x ( 208 Bi) (MeV) CISS05, August 2005; Wako, Tokyo, Japan 60 60

61 Angular distribution Use difference-of-angle method between narrow angular bins to extract angular distribution of the resonance d /d (mb/sr) reference point Data DW (deg) cm IVSGMR angular distribution confirmed CISS05, August 2005; Wako, Tokyo, Japan 61 61

62 Strength exhaustion S NM (%/MeV) IVSGMR E x =35 2 =11 4 t-singles tp-coincidences E x =37 1 = E x ( 208 Bi) (MeV) Systematic errors: extrapolation of continuum: 5% high-lying GT strength: small tail of the IVSGDR: 10% DWBA: 10% of measured value Summed strength: ( ) 10 3 fm 4 (contribution from IVGMR subtracted) method Normal modes Tamm-Dancoff Hamamoto & Sagawa PRC 62, Continuum RPA Rodin & Urin NPA 687, 276c HF-RPA * Auerbach & Klein PRC 30, 1032 Exhaustion(%) ( stat sys ) * Different operator, includes GT CISS05, August 2005; Wako, Tokyo, Japan 62 62

63 Proton decay from the IVSGMR IVGMR/SIVM IVGQR MeV -20 MeV IVGDR SDR GTR IAS E p -10 MeV Q E x Pb Q(g.s)= Bi S p = Pb CISS05, August 2005; Wako, Tokyo, Japan 63 63

64 Final state spectra d 3 /d t d p de x (mb/sr 2 MeV) E x ( 208 Bi)<30 MeV (IAS+GTR+SDR+...) 3p 1/2 2f 5/2 3p 3/2 1i 13/2 2f 7/2 1h 9/ E x ( 207 Bi) (MeV) d 3 /d t d p de x (mb/sr 2 MeV) p 3/2 2f 5/2 2f 7/2 3p 1/2 1i 13/2 IVSGMR (30<E x ( 208 Bi)<45 MeV difference of angles 1h 9/2 miss. val. 1h 11/2 1g 7/2,1g 9/ E x ( 207 Bi) (MeV) Comparison with 208 Pb( 3 He, ) Galès et al. Phys. Rep. 166,255 CISS05, August 2005; Wako, Tokyo, Japan 64 64

65 Final state population in 207 Pb Final state Data(%) Theory(%)* 3p 1/2 2f 5/2 3p 3/2 < i 13/ f 7/2 1h 9/2 13± h 11/2 22±8 1g 7/2 1g 9/2 17± All 52±12 66 *Rodin & Urin NPA 687, 276c (continuum RPA) Large discrepancies for partial branchings!! CISS05, August 2005; Wako, Tokyo, Japan 65 65

66 The ( 3 He,t) reaction at 0 degree. Cross sections at E( 3 He)=450 MeV, q=0 for ( 3 He,t) reactions dσ µµ k = N J B F + N J B GT στ dω ( π ) k i f f D 2 D 2 ( ( ) ( )) 2 2 τ στ h i T. N. Taddeucci et al., Nucl. Phys. A469, 125 (1987) I. Bergqvist et al., Nucl. Phys. A469, 648 (1987) Neutrino absorption cross sections Importance of charge-exchange reactions at intermediate energies CISS05, August 2005; Wako, Tokyo, Japan 66 66

67 Measuring GT strengths dσ ( q dω = 0) = KN D J στ 2 B( GT ) kinematic factor distortion factor Gamow-Teller strength nucleon-nucleus interaction Calibration of B(GT) to cross section for known transitions (e.g. from β-decay) CISS05, August 2005; Wako, Tokyo, Japan 67 67

68 M. Fujiwara et al. PRL 85 (2000) E x (MeV) B(GT) (p,n) ( 3 He,t) CISS05, August 2005; Wako, Tokyo, Japan 68 68

69 Why are Gamow-Teller transitions in pf-shell nuclei important? Role of pf-shell nuclei in supernova explosions: Core of supernova star is composed of pf-shell nuclei. Neutrino absorption cross sections by pf-shell nuclei are essential in understanding of nuclear synthesis by Supernova explosions in cosmos. Difficulties in shell model calculations for pf-shell nuclei. Importance of spin-isospin responses of pf-shell nuclei CISS05, August 2005; Wako, Tokyo, Japan 69 69

70 Beam line WS-course Grand-Raiden Spectrometer T. Wakasa et al., NIM A482 ( 02) 79. High-dispersive WS-course RCNP Ring Cyclotron CISS05, August 2005; Wako, Tokyo, Japan 70 70

71 CISS05, August 2005; Wako, Tokyo, Japan 71 71

72 Decomposition of the isospin component of the excited state in 58 Cu. Isospin of 58 Ni g.s. : T 0 =1 In principle, comparison among (n,p), (p,p), (p,n) spectra separates isospin components But, very difficult in practice because of high level density for T=1 and T=2 states. CG T=0 : T=1 : T=2 = 2:3:1 (T 0 =1) CISS05, August 2005; Wako, Tokyo, Japan 72 72

73 Comparison of ( 3 He,t) and (e,e ) spectra Comparison of ( 3 He,t) with (e,e ) spectra Try to separate isospini components At E x = MeV (T=1 region) Rather good correspondence At E x = MeV (T=2 region) No good correspondence Fujita et al., Phys. Lett. B 365, 29 (1996). Fujita et al., Eur. Phys. J A13, 411 (2002). (T=1): (T= 2) = 1 : 1 (T=1): (T= 2) = 3 : 1 CISS05, August 2005; Wako, Tokyo, Japan 73 73

74 (p, n) spectra for Fe and Ni Isotopes Rapaport & Sugarbaker Rev. Mod. Phys. ( 94) CISS05, August 2005; Wako, Tokyo, Japan 74 74

75 26 Mg(p, n) 26 Al & 26 Mg( 3 He,t) 26 Al spectra R. Madey et al., PRC 35 ( 87) 2001 IAS, 0 + Y. Fujita et al., PRC 67 ( 03) Prominent states are GT states and the IAS! CISS05, August 2005; Wako, Tokyo, Japan 75 75

76 54 Fe(p,n) & 54 Fe( 3 He,t) B(GT) 0.74(5) 54 Fe(p, n) 54 Co B.D. Anderson et al., PRC B(GT) 0.50(6) CISS05, August 2005; Wako, Tokyo, Japan 76 76

77 Determination of GT + Strength and its Astrophysical Implications CISS05, August 2005; Wako, Tokyo, Japan 77 77

78 CISS05, August 2005; Wako, Tokyo, Japan 78 78

79 Nuclear processes and energy household of supernovae CISS05, August 2005; Wako, Tokyo, Japan 79 79

80 CISS05, August 2005; Wako, Tokyo, Japan 80 80

81 CISS05, August 2005; Wako, Tokyo, Japan 81 81

82 10 7 CISS05, August 2005; Wako, Tokyo, Japan 82 82

83 Electron capture in fp-shell In supernova explosions, electron capture (EC) on fp-shell nuclei plays a dominant role during the last few days of a heavy star [presupernova stage; deleptonization core collapse subsequent type IIa Supernova (SN) explosion] Bethe et al. (1979) The rate for EC is governed by the GT + strength distribution at low excitation energy; not accessible to β-decay. Fuller, Fowler and Newman (FFN) ( ); estimates of stellar rates in stellar environments using s.p. model. Caurier et al., Martínez-Pinedo & Langanke (1999), Otsuka et al. Large shell-model calculations marked deviations from FFN EC rate; generally smaller EC rates. Experiments and theory relied on (n,p) data (TRIUMF) which have a rather poor energy resolution CISS05, August 2005; Wako, Tokyo, Japan 83 83

84 CISS05, August 2005; Wako, Tokyo, Japan 84 84

85 fp-shell nuclei: large scale shell model calculations E. Caurier et al. NPA 653 (1999) 439 Stellar weak reaction rates with improved reliability Large scale shell model (SM) calculations Tuned to reproduce GT + strength measured in (n,p) (n,p) data from TRIUMF GT + strength from SM Folded with energy resolution Case study: 58 Ni CISS05, August 2005; Wako, Tokyo, Japan 85 85

86 Exclusive excitations S= T=1: (d, 2 He) 2 He p p d A, Z A, Z-1 3 S 1 deuteron 1 S 0 di-proton ( 2 He) 1 S 0 dominates if (relative) proton kinetic energy ε < 1 MeV (n,p)-type probe with exclusive S=1 character (GT + transitions) But near 0 : tremendous background from d-breakup CISS05, August 2005; Wako, Tokyo, Japan 86 86

87 KVI Big-Bite Spectrometer (BBS) in coincidence with EDEN (neutrons) SiLi ball (protons) CISS05, August 2005; Wako, Tokyo, Japan 87 87

88 Setup: ESN detector Focal-Plane Detector: (FPDS): 2 VDCs Focal-Plane Polarimeter: (FPP): 4 MWPCs & graphite analyzer M. Hagemann et al., NIM A 437 (1999) 459 V.M. Hannen et al., NIM A 500 (2003) 68 features a.o.: fast readout VDC readout pipeline TDC s VDC decoding using imaging techniques DSP based online analysis Bari, Darmstadt, Gent, Iserlohn, KVI, Milano, Münster, TRIUMF CISS05, August 2005; Wako, Tokyo, Japan 88 88

89 Good double tracking Use VDC information Good phase space coverage for small relative proton energies S. Rakers et al. NIM A481 (2002) 253 phase space limited by dω and p/p measured CISS05, August 2005; Wako, Tokyo, Japan 89 89

90 Exclusive measurement of S= T =1 strength: 12 C(d, 2 He) 12 B E 0 = 171 MeV, θ = 0 1/10 shell model calculations 4 ħω & 6 ħω (G. Martinez-Pinedo) B (GT + ) (S. Rakers) CISS05, August 2005; Wako, Tokyo, Japan 90 90

91 (p,n) vs (d, 2 He): calibration Self-conjugate 24 Mg S. Rakers et al. PRC 65 (2002) CISS05, August 2005; Wako, Tokyo, Japan 91 91

92 Experimental cross section and GT strength Bexp(GT+) = dσ (q = 0) dω dσ (GT ) dω 1 unit cross section extrapolated (DWBA) CISS05, August 2005; Wako, Tokyo, Japan 92 92

93 GT Strength in 12 B and 24 Na from (d, 2 He) reaction Target Reference data Present data E x B(GT - ) E x dσ/dω(q=0) σ(l=0)/σ(τοτ) B(GT + ) [MeV] [MeV] [mb/sr] (q=0) (C=0.267) 12 B ± ± ± ± Na ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ±0.004 CISS05, August 2005; Wako, Tokyo, Japan 93 93

94 (d, 2 He) as GT + probe in fp shell nuclei 58 Ni(d, 2 He) 58 Co E=85A MeV 58 Ni(n,p) 58 Co E=198 MeV CISS05, August 2005; Wako, Tokyo, Japan 94 94

95 GT Strength in 58 Co from (d, 2 He) reaction E x dσ/dσ(0.5 ) σ(l=0)/σ(τοτ) B(GT+) [MeV] [mb/sr] ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ±0.09 CISS05, August 2005; Wako, Tokyo, Japan 95 95

96 GT + strength: comparison (n,p), (d, 2 He) & theory Up to 4 MeV excitation: 13 GT transitions measured (d, 2 He) Strength rebinned in 1 MeV bins Significant differences Pinedo/Langanke Caurier et al.. Updated shell model calculations by Pinedo/Langanke CISS05, August 2005; Wako, Tokyo, Japan 96 96

97 Electron capture rate 2 ( Q ω) F( Z, ) λ B ( GT) ω p ω S ( ω, T) dω ec i + i i ω l With B i (GT) Gamow-Teller strength distribution ω and p energy and momentum electrons S e (ω,t) Fermi-Dirac distribution electron gas at temperature T e CISS05, August 2005; Wako, Tokyo, Japan 97 97

98 e - -capture rates using experimental strengths (Pinedo, Langanke) T 9 = 2.26 ρ = g/cm 3 Y e = 0.48 Evolution of core of 25 M סּ star. Conditions following silicon depletion. [Heger et al., Astrophys. J. 560 (2001) 307] T 9 = 4.05 ρ = g/cm 3 Y e = T 9 Calculate EC rates for g.s. as a function of T 9 Strength deviations at low excitation: rates deviation at low T CISS05, August 2005; Wako, Tokyo, Japan 98 98

99 58 Ni: comparison of e-capture rates theory/experiment λ ec / λ ec (d, 2 He) T 9 (n,p) 198 MeV Pinedo, Langanke Caurier et al. FFN Influence of GT strength distribution on calculated capture rate is dramatic, especially at low temperatures rates vary up to a factor 5-6 FFN not too far off large scale shell-model calculations fail at low T calculations with improved residual interaction in reasonable agreement CISS05, August 2005; Wako, Tokyo, Japan 99 99

100 51 V(d, 2 He) 51 Ti: B(GT + ) for proton-odd fp-shell nucleus 51 V g.s. (J π =7/2, T=5/2) 51 Ti (J π =5/2, 7/2, 9/2, T=7/2) Independent single-particle model (FFN): E x (GTR)=3.83 MeV C. Bäumer et al., PRC 68, (R) (2003) CISS05, August 2005; Wako, Tokyo, Japan

101 C. Bäumer et al., PRC 68, (R) (2003) CISS05, August 2005; Wako, Tokyo, Japan

102 51 V(d, 2 He): Angular distributions of dσ/dω CISS05, August 2005; Wako, Tokyo, Japan

103 51 V(d, 2 He): Comparison with shell-model calculations Experimental result Calculations G. Martínez-Pinedo, K. Langanke CISS05, August 2005; Wako, Tokyo, Japan

104 50 V(d, 2 He): GT + transitions from odd-odd nucleus 50 V GT + 50 Ti J π =6 + J π =5 +, 6 +, 7 + T=2 T=3 GT-centroid located at ~ 9 MeV CISS05, August 2005; Wako, Tokyo, Japan

105 d 2 σ/dωde in mb/(sr 40keV) CISS05, August 2005; Wako, Tokyo, Japan d 2 σ/dωde in mb/(sr 40keV)

106 56 Fe(d, 2 He): Comparison with shell-model calculations Experiment Full fp-shell model calculations (KG3G) (G. Martínez-Pinedo) CISS05, August 2005; Wako, Tokyo, Japan

d 2 σ/dωde in mb/(sr 40keV) CISS05, 18-23 August 2005;

107 d 2 σ/dωde in mb/(sr 40keV) CISS05, August 2005; Wako, Tokyo, Japan d 2 σ/dωde in mb/(sr 40keV)

108 61 Ni(d, 2 He) 61 Co: GT + distribution 57 Fe(d, 2 He) 57 Mn: GT + distribution CISS05, August 2005; Wako, Tokyo, Japan

109 67 Zn(d, 2 He) 67 Cu: GT + distribution No shell-model calculations yet CISS05, August 2005; Wako, Tokyo, Japan

110 GT + centroid comparison 4.1 CISS05, August 2005; Wako, Tokyo, Japan

111 Conclusions Presupernova models depend sensitively on EC rates. GT + transitions in fp-shell nuclei play a decisive role in determining EC rates and thus provide input into modeling of explosion dynamics of massive stars. Large shell-model calculations are needed especially as function of T. (Caurier et al.; Martínez-Pinedo & Langanke [KB3G]; Otsuka et al. [GXPF]) smaller EC rates for A=45-60 than FFN Larger Y e (electron to baryon ratio) and smaller iron core mass (Heger et al.) New high resolution (d, 2 He) experiments provide essential tests for shell model calculations at 0 T. CISS05, August 2005; Wako, Tokyo, Japan

112 Outlook Radioactive ion beams will be available at energies where it will be possible to study GRs (RIKEN, SPIRAL2, NSCL, FAIR, RIA, EURISOL) Multipole strength functions in unstable n-rich nuclei soft modes, pygmy resonances, low-lying non-collective strength, modification of effective NN interaction but also various Giant mulitpole resonances ISGMR in a long chain of isotopes determine K sym Determine GT strength in unstable sd & fp shell nuclei Use GRs as tools to determine n-skin [IV(S)GDR] Exotic excitations such as Double GT CISS05, August 2005; Wako, Tokyo, Japan

113 SHARAQ Spectroscopy of HAdron systems with RadioActive Quantum beams RI Beam (E = MeV/A) as a new PROBE beam (stable) to nuclear systems Large Isospin iso-tensor excitations Large internal energy (q,ω) inaccessible by stable beams beam (unstable) ejectile (unstable) large negative Q-value ejectile (stable) small Q-value ω IVSMR Multi n s DGT GT SHARAQ Photon line: q=ω Stable Beam Exothermal Charge Exchange Reactions q CISS05, August 2005; Wako, Tokyo, Japan

114 END CISS05, August 2005; Wako, Tokyo, Japan

Spin-isospin responses by charge-exchange reactions and implications for astrophysics

Spin-isospin responses by charge-exchange reactions and implications for astrophysics Muhsin N. Harakeh KVI, Groningen & GANIL, Caen The 4 th International Symposium on Neutrinos and Dark Matter in Nuclear