Direct Measurement of the 8Li + d reactions of astrophysical interest 10th International Symposium on Origin of Matter and Evolution of Galaxies (OMEG07) Direct Measurement of the 8Li + d reactions of astrophysical interest Advanced Science Research Center (ASRC) Japan Atomic Energy Agency(JAEA) Takashi Hashimoto Collaborators KEK H. Ishiyama, Y. X. Watanabe, Y. Hirayama, N. Imai, H. Miyatake, S. C. Jeong, M.-H. Tanaka, N. Yoshikawa, T. Nomura, M. Okada, S. Arai JAEA S. Mitsuoka, K. Nishio, T. K. Sato, A. Osa, S. Ichikawa, M. Matsuda, H. Ikezoe OECU 　 S. K. Das, Y. Mizoi, T. Fukuda RIKEN S. Bishop Osaka Univ. A. Sato, T. Shimoda

Table of Contents Introduction 2.Experiment 3.Discussion 4.Summary Motivation of this work TRIAC 8Li beam profile Experimental setup Excitation functions Reaction rates They are collaborators.

Introduction Explosive Nucleosynthesis prosess (early universe, supernovae …) stable unstable 8B 10B 11B 12B 7Be 9Be 10Be 11Be Proton (d,t) (d,α) (d,p) Ex(10Be) 22.1 23.1 MeV M. J. Balbes, et. al., Nucl. Phys. A584(1995)315 6Li 7Li 8Li 9Li 22.4 21.8 23.0 3He 4He 6He 8He Neutron T9(109K)=1-3

2. Experiment KEK-JAEA joint RNB project E(MeV) counts X position(mm) Y position(mm) 8Li1+ α β ２％（FWHM) TRIAC ; Tokai Radioactive Ion Accelerator Complex KEK-JAEA joint RNB project Experimental area The TRIAC is an ISOL-based radioactive nuclear beam facility under a joint project of KEK and JAEA. A 7Li beam was accelerated 64MeV with the intensity of about 100pnA by JAEA tandem accelerator. The 7Li beam was irradiated on the 0.82g/cm^2 thick 13C target. The produced 8Li particles are ionized and mass separated singly charged ions as JAEA-ISOL. Those 8Li ions are accelerated by two linear accelerator. The 8Li beam energy can be changed from 0.18MeV/u to 1.1MeV/u. In the experiment, the 8Li beam energies were set those energies, corresponding to those cm energies. The diameter and beam energy resolution of 8Li beam onto the secondary CD2 target were 8mm and 3%, FWHM. The purity was achieved to be 100%. The typical and maximum intensity are 100kcps and 300kcps, respectively. Those profile was sama value in all beam energies. RNB can be provided with variable energy from 0.18 to 1.1 MeV/u Ecm = 1.2、1.1、1.0、0.8、0.7、0.5、0.4、0.3 MeV （T9=1-3) 8Li beam : I =105 pps on target　（max 3×105 kpps) Impurity < 10-2 %　(16O2+)

Experimental setup@TRIAC Angular distribution @ θcm = 26°-140° Ecm = 1.0 MeV dE-E θ=45° dE: DSSD E: SSD SSD1θ=100° SSD2θ=120° p, t, α Coincidence p, t, α CD2 :1.3μm Al plate 8Li beam 9Li, 7Li, 6He Beam monitor Plastic scintillator SSSD2 θ=70° The experimental setup consisted of a dE-E telescope, two SSDs and two single-strip type SSD and plastic scintillator. The dE-E telescope on the downstream side of the target subtended 22-68 degree in lab system. It consisted of 43um thick Double strip type SSD and 375um thick SSD. The DSSD has 16 strips both horizontal and vertical direction. It can measure the dE-E particle identification spectra and scattered angle. The SSD array on the upstream side of the target subtended 86-132 degree in lab system. This SSD array was measured total energy and scattered angle of emitted particles. The covered angle of the SSDs and dE-E telescope in cm system were between 15 and 55 degree and between 100 and 150, respectively. The SSSDs on the downstream side of the target subtended 15-82 degree in lab system on the opposite of beam. Those detectors were measured total energy and scattered angle of 7Li, the event selection was performed by a coincident with the SSDs events. The plastic scintillator was placed the downstream side of the target, and the distance from the target was 412mm. It used as a monitor of the number of injected beam by measuring beta ray form 8Li beam. SSSD1 θ=30° DSSD： Double Sided strip Silicon Detector 50×50mm、x,y=16strips SSSD: Sigle Sided strip Silicon Detector 50×50mm、x=16strips

An enhancement of the excitation function at around Ecm=0.8MeV 8Li(d, t)7Li reaction An enhancement of the excitation function at around Ecm=0.8MeV Ex(10Be)= 22.4 MeV The present result provided the first data in low energy region below 1.5 MeV, and covers the Gamow peaks from T9=1 to 3. The angular distributions are isotropic except for one at Ecm =1.5 MeV. Because, compound reaction seems to dominate those large cross sections. This state might play a role in the resonance at this energy in the reaction. Then, the ratio of the partial cross section to the first excited state of 7Li to the total cross section is shown

An enhancement of the excitation function at around Ecm=1.0 MeV 8Li(d, p)9Li reaction Ecm = 0.7 MeV An enhancement of the excitation function at around Ecm=1.0 MeV Upper limit @ Nortre Dame

Reaction rate 8Li(d, t)7Li 8Li(d, p)9Li The present result is about one order of magnitude than the previous result The present result is about two order of magnitude than the previous result The effect of the present result in a network calculation, for example inhomogeneous big bang and super nova explosion, is still in progress under the calibration with Kajino group. The resonance-like structures in the 8Li(d, p)9Li and 8Li(d, t)7Li reactions have strong influence on the reaction rates.

Summary The direct measurement of the 8Li + d reactions has been performed at TRIAC 　　 8Li beam　 Intensity 105 pps, purity 100% 　　　　　 Ecm=1.2、1.1、1.0、0.8、0.7、0.5、0.4、0.3 MeV → T9=1 to 3 8Li(d, t)7Li reaction An enhancement in the excitation function at around Ecm=0.8 MeV, implying a resonance state located at around 22.4 MeV in 10Be.　　　　 　　 8Li(d, p)7Li reaction An enhancement in the excitation function at around Ecm=1.0 MeV (Preliminary result) Reaction Rate 　The resonance-like structures in the 8Li(d, p)9Li and 8Li(d, t)7Li reactions have strong influence on the reaction rates. In Summary, 読め！ We collaborate with Kajino group on examining what kind of effect this result gives to nucleosynthesis.

Future plan Resonance search and assignment of Jπ　of highly excited state in 10Be will be performed by utilizing a technique of deuteron elastic resonance scattering with 8Li beam and thick CD2 target. Purpose: Assignment of Jπ for the observed resonances →　Nuclear structure of 10Be Resonance search less than Ecm = 0.3 MeV → Astrophysical Reaction rate