Spin-isospin studies with the SHARAQ Spectrometer Tomohiro Uesaka & Y. Sasamoto, K. Miki, S. Noji University of Tokyo for the SHARAQ collaboration Aizu2010 Nov 10  13, 2010

T. Uesaka, Center for Nuclear Study, University of Tokyo RI beam RIKEN Superconducting Ring Cyclotron (SRC) Isotope separator BigRIPS SHARAQ

T. Uesaka, Center for Nuclear Study, University of Tokyo What is SHARAQ? SHARAQ is a HIGH-RESOLUTION magnetic spectrometer constructed at RIBF by University of Tokyo - RIKEN collaboration.

T. Uesaka, Center for Nuclear Study, University of Tokyo SDQ D1 D2 Q3 Design Specifications of SHARAQ Maximum rigidity 6.8 Tm Momentum resolution dp/p = 1/14700 Angular resolution ~ 1 mrad Momentum acceptance ± 1% Angular acceptance ~ 5 msr QQDQD T.U. et al., NIMB B 266 (2008) "GANIL-made" CRDC

T. Uesaka, Center for Nuclear Study, University of Tokyo Nuclear Spin-Isospin Responses For more than 70 years, we have dedicated our efforts to study of nuclear spin-isospin responses. → knowledge of fundamental properties of finite nuclei and infinite nuclear matter in-medium interaction correlation in nuclei → essential inputs to astrophysics nucleo-synthesis, neutron star physics... neutrino physics weak response of nuclei

T. Uesaka, Center for Nuclear Study, University of Tokyo Isovector monopole resonances higher tone of GT & IAS  T=1  L=0  S= 0, 1 2h  excitations Experimental data are scarce. no good (efficient) probes to probe IV(S)MR so far

T. Uesaka, Center for Nuclear Study, University of Tokyo RI beams induced charge exchange reactions Spectroscopy with RI-beam induced reactions Traditional example: (t, 3 He) experiments POTENTIAL of (new) RI beam induced reactions New SELECTIVITIES (  T,  S,  L,  ) missing in stable-beam induced reactions ex. the ( 10 C, 10 B*(IAS)) reaction to probe isovector non-spin-flip (  T=1,  S=0) excitations. → search for Isovector Monopole Resonances Access to kinematical region which are inaccessible by stable beams. large Q-value in RI beam induced charge exchange reaction (exothermic) → RECOILLESS excitation of HIGH-E x states Isovector Spin Monopole Resonance via the ( 12 N, 12 C) reaction Double Gamow-Teller Resonance via the ( 10 C, 10 Be) reactions Tetra-neutron state via the 4 He( 8 He, 8 Be[=2  ]) reaction

T. Uesaka, Center for Nuclear Study, University of Tokyo First series of experiments with SHARAQ Studies of IV(S)MR, taking advantages of RI beam induced charge exchange reactions (RICE) 90 Zr, 208 Pb(t, 3 He) at 300 MeV/u (Miki et al.) search for  + type isovector spin monopole resonances 7 Li, 90 Zr ( 10 C, 10 B  ) at 200 MeV/u (Sasamoto et al.) search for  + type isovector non-spin monopole resonances 90 Zr( 12 N, 12 C) at 200 MeV/u (Noji et al.) establish exothermic charge exchange reaction to probe   type isovector spin monopole resonances

90 Zr, 208 Pb(t, 3 He) at 300 MeV/u (Miki et al.)

T. Uesaka, Center for Nuclear Study, University of Tokyo Experimental conditions Beam Primary : 4 He 320MeV/u 300pnA Secondary : triton 300MeV/u 1x10 7 pps Purity > 99% Obtained spectra 208 Pb(t, 3 He) 208 Tl 90 Zr (t, 3 He) 90 Y Resolution(FWHM)  E ～ 2.5MeV - energy spread of 2 nd beam – 1.9MeV - energy loss in target – 1.4MeV  ～ 0.5deg - angular spread of 2 nd beam – 7mrad - multiple scattering in target – 6mrad 0 < E x < 70 MeV 0 <  < 3

T. Uesaka, Center for Nuclear Study, University of Tokyo Stat. accuracy (0deg) ~ 2% for 1msr ・ 1MeV –bin Bumps at 4MeV, 15MeV -- peak around the forward angle   L=0 ? 208 Pb(t, 3 He) MeV/u

T. Uesaka, Center for Nuclear Study, University of Tokyo IVSMR(  + ) for 208 Pb IVSMR(  L=0)  Forward-peak Comparison between deg.vs deg spectra Miki et al.

T. Uesaka, Center for Nuclear Study, University of Tokyo IVSMR(  + ) for 208 Pb IVSMR(  L=0)  Forward-peak Comparison between deg.vs deg spectra Significant  L=0 component around 12MeV First observation of  + -type IVSMR First observation of  + -type IVSMR Miki et al.

T. Uesaka, Center for Nuclear Study, University of Tokyo IVSMR(  L=0)  Forward-peak Comparison between deg.vs deg spectra Significant  L=0 component around 12MeV Theoretical predictions : TDA(SGII), TDA(SIII) Hamamoto, Sagawa : Phys.Rev.C 62 (2000) IVSMR(  + ) for 208 Pb IVSMR TDA(SIII) reproduces the data well. First observation of  + -type IVSMR First observation of  + -type IVSMR Miki et al. Very Preliminary

T. Uesaka, Center for Nuclear Study, University of Tokyo IVSMR(  L=0)  Forward-peak Comparison between deg.vs deg spectra Significant  L=0 component around 20MeV Theoretical predictions : TDA(SGII), TDA(SIII) Hamamoto, Sagawa : Phys.Rev.C 62 (2000) IVSMR(  + ) for 90 Zr SDR IVSMR Detailed analyses to deduce absolute value of the transition strength are in progress Miki et al. Very Preliminary

90 Zr( 12 N, 12 C) at 200 MeV/u (Noji et al.)

T. Uesaka, Center for Nuclear Study, University of Tokyo   type IVSMR ( 12 N, 12 C) reaction at 200 － 300 MeV: BEST probe to   type IVSMR Selective excitation of  mode 12 N(1 + ) → 12 C (0 + ) Surface sensitivity (HI reaction) Exothermic reaction good momentum matching 90 Zr( 12 C, 12 N) data were taken Analysis to subtract BG is now being done.

7 Li, 90 Zr ( 10 C, 10 B  ) at 200 MeV/u (Sasamoto et al.)

T. Uesaka, Center for Nuclear Study, University of Tokyo ( 10 C, 10 B  ) Reaction Use super-allowed Fermi transition (in projectile) to probe isovector non-spinflip mode in target nuclei  T=1,  S=0 NO stable beam induced reaction with the selectivity 1022 keV g-ray is a signature of the non-spinflip transition

T. Uesaka, Center for Nuclear Study, University of Tokyo 7 Li( 10 C, 10 B  ) : proof of the principle 1022 keV  -ray Sasamoto et al.

T. Uesaka, Center for Nuclear Study, University of Tokyo Search for IV-nonspin-MR in 90 Zr Sasamoto et al.

T. Uesaka, Center for Nuclear Study, University of Tokyo Summary RI beam induced charge exchange (RICE) reactions can be tools to probe hardly studied states such as IV(S)MR double GT states... In the first series of SHARAQ experiments, IV(S)MR are studied by taking advantage of RICE 90 Zr, 208 Pb(t, 3 He) at 300 MeV/u (Miki et al.) 7 Li, 90 Zr ( 10 C, 10 B  ) at 200 MeV/u (Sasamoto et al.) 90 Zr( 12 N, 12 C) at 200 MeV/u (Noji et al.)