1. Studies on alpha-induced astrophysical reactions using the low-energy RI beam separator CRIB Studies on alpha-induced astrophysical reactions using the low-energy RI beam separator CRIB Center for Nuclear Study, Univ. of Tokyo Hidetoshi Yamaguchi, D. Kahl, T. Nakao,Y. Wakabayashi, S. Kubono, T. Hashimoto, S. Hayakawa, T. Kawabata, N. Iwasa, T. Teranishi, Y.K. Kwon, D.N. Binh, L.H. Khiem, and N.G. Duy

2. OutlineOutline CRIB…low-energy RI beam facility of the Univ. of Tokyo, located in RIBF of RIKEN Nishina center. Recent projects…emphasis on  -induced astrophysical reactions  Alpha resonant scattering for (  ) reaction study [e.g. 7 Li/ 7 Be+   Direct measurement of  p  reactions  e.g. 18 Ne/ 30 S(  p  2013 Jun 4 INPC 2013

3. CRIBCRIB CNS Radio-Isotope Beam separator, operated by CNS (Univ. of Tokyo), located at RIBF (RIKEN Nishina Center).  Low-energy(<10MeV/u) RI beams by in-flight method.  Primary beam from K=70 AVF cyclotron.  Momentum (Magnetic rigidity) separation by “double achromatic” system, and velocity separation by a Wien filter.  Orbit radius: 90 cm, solid angle: 5.6 msr, momentum resolution: 1/850. INPC 2013 2013 Jun 4

4. Low-Energy RI beam Productions at CRIB Direct reactions such as (p,n), (d,p) and ( 3 He,n) in inverse kinematics are mainly used for the production….large cross section Many RI beams have been produced at CRIB: typically 10 4 -10 6 pps 7 Be…2 x 10 8 pps available with a cryogenic target. H. Yamaguchi et al., NIM A (2008) RI beam at CRIB / Stable nuclei INPC 2013 2013 Jun 4

5. International collaborations at CRIB CRIB experiments performed in 2007-2011, by collaborated members of CNS and other institutes: INPC 2013 2013 Jun 4

6. Recent research projects Proton/alpha resonant scattering 26 Si+p (Collaborated with Chung-Ang, Korea) H.S. Jung et al., published at PRC (2012). 7 Li/ 7 Be+  (CNS) H. Yamaguchi et al., PRC (2011&2013). 21 Na+p, 22 Na+p [ 18 Ne( ,p), Ne-Na cycle] (IMP/CIAE, China) 17 F+p [Resonances for 14 O( ,p)](IMP/CIAE, China) (α,p) reaction measurement, Active target (GEM-MSTPC) 18 Ne( ,p) (CNS, Hashimoto (now at RCNP)) 30 S(α, p ) (CNS, Daid Kahl) 22 Mg(α, p ) (IOP, Vietnam, Nguyen Ngoc Duy) 44 Ti( ,p) (KEK, Ishiyama) … 44 Ti beam test successful. (  ) 16 N ⇒ 16 O* ⇒ 12 C+  for 12 C(  ) (Catania, Italy, S. Cherubini) Reaction mechanism 8 B+Pb (Padova, Italy, C. Signorini) β-decay 7 Be lifetime in metal (Tohoku Univ, Otsuki) 2013 Jun 4 INPC 2013

7. 7 Li+  7 Be+  study 7 Li(  ) 11 B …important at high-T, as a production reaction of 11 B (the -process in core-collapse supernovae). 7 Be(  ) 11 B … one of the reaction in hot p-p chain, relevant at high-T. Contribution of higher-lying resonances unknown.  -cluster structure in 11 B/ 11 C : 2  +t / 2  + 3 He cluster states are known to exist (similar to the dilute cluster structure in 12 C.) Several “bands” which have  -cluster structure could be formed. We can study the band and cluster structure more in detail. INPC 2013 2013 Jun 4

8. 7 Be(  ) p-process calculation (T 9 >1) shows considerable contribution by 10 B( ,p) 13 C and 7 Be(  ) 11 C as much as the triple-alpha process. S. Wanajo et al., Astrophys. J (2010) 2013 Jun 4 INPC 2013

9. 7 Li/ 7 Be+α; method  “Thick target with inverse kinematics” Resonant elastic scatterings can be measured at  cm=180 deg. MCP 2013 Jun 4 INPC 2013

10. 7 Be+  Excitation functions 4 excitation functions… new information on resonant widths, spin, and parity. H. Yamaguchi et al., PRC, Published in Mar. 2013. 2013 Jun 4 INPC 2013

11. Resonant contribution to 7 Be(  ) Small but not negligible contribution compared to lower-lying states (~10%). 2013 Jun 4 INPC 2013

12. (Rotational) bands in 11 C 2 rotational bands (K=3/2 +,5/2 + ) were suggested in Soic. et al. (2004). J  =9/2 + was assigned for the resonance at 12.4 MeV, and it can be the member of K=3/2 + band. A negative-parity band is proposed. 2  + 3 He cluster? 2013 Jun 4 INPC 2013

13. Interpretation of the new negative-parity band ( 11 B case) 2013 Jun 4 INPC 2013

14. Study on the  p-process Study on the  p-process  p-process: ( ,p),(p,  ) reactions occur faster than β-decay at high temperature. Accelerates the rp-process (Wallace and Woosley, 1981). Suitable objective for CRIB  Not many direct measurements of ( ,p) reactions have been performed in other facilities.  Involves A=18-30, proton rich unstable nuclei.  T=1.5GK, close to the beam energy at CRIB. 2013 Jun 4 INPC 2013

15. 18 Ne( ,p) (T. Hashimoto; RCNP) 11 C 12 C 13 C 13 N 14 N 15 N 12 N 16 O 17 O 18 O 9C9C 10 C 11 N 15 O 14 O 19 F 18 F 17 F 20 Ne 21 Ne 22 Ne 19 Ne 18 Ne stable unstable hot-CNO 12 C(p, γ) 13 N(p, γ) 14 O(  ) 14 N(p,  ) 15 O(  ) 15 N(p,  ) 12 C second hot CNO cycle 14 O(α, p) 17 F(p, γ) 18 Ne(  ) 18 F(p, α) 15 O(  ) 15 O(p, α) 12 C 18 Ne(α, p) 21 Na 22 Na 23 Na 21 Na 20 Na 18 Ne( , p) 21 Na is an important breakout reaction from hot-CNO cycle to the rp-process (B to C in the figure) A: hot-CNO B: second hot-CNO C: 18 Ne( , p) 21 Na D: 18 Ne(2p,  ) 20 Mg E: 15 O(2p,  ) 17 F J. Phys. G: Nucl. Part. Phys. 25 (1999)R133 17 Ne X-ray bursts 2013 Jun 4 INPC 2013 Relevant energy (temperature): E cm = 0.5 - 3.8 MeV (T = 0.6 - 3 GK).

16. Experimental Setup He (90%) +CO 2 (10%) mixture gas(160 torr) z x y Acts as a He target and a detector (TPC) simultaneously 3-dimentional trajectory and energy loss can be measured ⇒ Good event identification. 18 Ne beam Beam monitor INPC 2013 2013 Jun 4

17. Typical event of 18 Ne( , p) 21 Na reaction Preliminary Si telescopes Total energy (MeV) p   Stopped in first layer) Energy loss in first layer (MeV) Pad No. dE/Pad (MeV) X position (cm) Y position (cm) Analysis is in progress … 18 Ne 21 Na 18 Ne 21 Na 18 Ne 21 Na 18 Ne Preliminary 2013 Jun 4 INPC 2013 Reaction events are observed !

18. CRIB - Recent Publications Proton resonant scattering 13 N+p; Teranishi et al., PLB (2007), 21 Na/ 22 Mg+p; J.J. He et al., PRC (2007/2009), Eur. Phys. J (2010), 7 Be+p; H. Yamaguchi et al., PLB (2009). 26 Si+p (Chung-Ang Univ., SNU) H.S. Jung et al., Phys. Rev. C (2012). 25 Al+p; Jun Chen et al., Phys. Rev. C(2012): related to galactic gamma-ray from 26 Al. Alpha resonant scattering 7 Li+  ; H. Yamaguchi et al., Phys. Rev (2011). 7 Be+  ; H. Yamaguchi et al., Phys. Rev. C (2013). Other reactions 21 Na( ,p) direct reaction measurement; Dam N. Binh, Dr. thesis of Univ. of Tokyo (2009). 11 C( ,p) direct reaction measurement; S. Hayakawa, Dr. thesis of Univ. of Tokyo (2012), another paper in preparation. 17 F+ 12 C; Quasi-elastic scattering G.L. Zhang et al., Eur. Phys. J. A (2012). 12 N(p,  ) by ANC B. Guo et al., Phys. Rev. C (2013). 2013 Jun 4 INPC 2013

19. 2013 Jun 4 SummarySummary CRIB is a low-energy RI beam facility operated by CNS, University of Tokyo, providing RI beams of good intensity and purity. Standard experiments: Proton/alpha resonant scattering, direct ( ,p) reaction measurement using an active target (GEM-MSTPC) 7 Li+ , 7 Be+  Strong resonances were observed. The “thick target method with inverse kinematics” could be applied to many nuclides. We can study astrophysical reactions and alpha-cluster structures. Active target Has been used in several ( ,p) measurements, analysis is in progress. We welcome new users and new ideas!