Presentation is loading. Please wait.

Presentation is loading. Please wait.

Photonuclear reactions in astrophysics

Similar presentations


Presentation on theme: "Photonuclear reactions in astrophysics"— Presentation transcript:

1 Photonuclear reactions in astrophysics
中日NP2006: 上海(Shanghai), May , 2006 H. Utsunomiya (Konan Univ) 1 Nucleosynthesis of heavy elements 2 Photonuclear reactions in stars 3 Laboratory studies: 12 nuclei D, Be-9, Se-80, Zr-90,94, Pd-108, La-139, Pr-141, Ta-181,W-186, Re-187, Os-188 4 Conclusions

2 Collaborators 1) <Konan> S. Goko, A. Makinaga, H. Akimune, T. Kaihori, S. Hohara 2) <AIST> H. Toyokawa, K. Kudo, A. Uritani, H. Harano, T. Matsumoto 3) <Kyoto> H. Ohgaki 4) <Numazu> K. Sumiyoshi 5) <NAO> T. Kajino 6) <Darmstadt> P. Mohr 7) <SPring-8> H. Yonehara, K. Soutome, N. Kumagai, H. Ohkuma, 8) <Texas A&M> Y.W. Lui 9) <Univ. Libre de Bruxelles> M. Arnould, S. Goriely, M. Rayet 10) <Orsay> E. Khan 11) <JAEA> H. Harada, F.Kitatani, K.Y. Hara, T. Hayakawa, H. Shizuma

3 Solar abundances of heavy elements
Metal: 2% (mass %) 3W (what, where, when) & 1H (how) Who? (Nature or God)

4 Nucleosynthesis of heavy elements
35 neutron-deficient nuclei with small solar abundances:74Se - 196Hg p-nuclei GSI Darmstadt

5 Stellar Model of the p-process
Arnould (1976) Woosley & Haward (1978) Rayet et al. (1995) Rauscher et al. (2002) Arnould & Goriely (2003) 2000 nuclei,20000 reactions : Photodisintegration: (g,n)(g,p)(g,a) Capture reactions: (n,g)(p,g)(a,g) Weak transformation: b-decays, e±-captures, (anti)neutrino-captures Temperature:(1.5 ~3.5) x 109 K Promising sites: O/Ne-rich layer of massive stars during their explosions as Type II(core collapse)-supernovae or in pre-supernova phase Type Ia-supernovae

6 Photoreaction rate for nuclei in the ground state
j= n, p, a Planck distribution neutron channel Gamow peak GDR cross section Planck distribution

7 Stellar Photoreaction Rate
(nucleus in state m) Z, A-1 Z, A Nuclei are thermalized under stellar conditions

8 Hauser-Feshbach model
3 important nuclear parameters g transmission coefficient Particle (n,p,a) transmission coefficient Level density

9 National Institute of Advanced Industrial Science and Technology
AIST 産総研

10 Inverse Compton Scattering
Eg = 1 – 40 MeV Inverse Compton Scattering “photon accelerator” g = Ee/mc2

11 AIST (産総研) Experimental Setup
TERAS:Tsukuba Electron Ring for Accelerating and storage

12 Laser System TERAS mirror depolarizer+expander lens mirror Laser
Nd:YVO4

13 Triple Ring Neutron Detector System
Triple ring detector: 20 3He counters (4 x 8 x 8 ) triple ring detectors Monitor: NaI(Tl)

14 p process origin of 180Tam : stot at 109 K
Arnould, Goriely s process origin of 180Tam : sm at 108 K Kaeppeler 180W 181W 182W 183W Unknown sm : 179Ta(n,g)180Tam 180m 179Ta 181Ta 182Ta 180g 180m 176Hf 177Hf 178Hf 179Hf 181Hf 180g s process r process

15 180Ta (odd-odd p-nucleus)
Nature’s rarest isotope The one and only naturally-occurring isomer 181Ta(g,n)180Ta H. Utsunomiya et al. 2003 Phys. Rev. C63, Extra E1-strength at low energy

16 Novel probe of Nuclear Level Density of 180Ta
Partial cross sections for the isomeric state : sm(E) for 181Ta(g,n)180Tam Novel probe of Nuclear Level Density of 180Ta 9/2ー 7/2ー 5/2ー 5ー 4ー 3ー 2ー s-wave neutron 75 keV > 1015 y 180Tam 9− E1 8.152 h 1− 180Ta Selective multistep transitions between high spin states 5ー → 6+ → 7ー → 8+ → 9ー 7/2+ 181Ta

17 181Ta 197Au Total cross sections: stot(E) for 181Ta(g,n)180Ta
Direct neutron counting 181Ta 197Au sm(E)= stot (E) - sgs(E) Partial cross sections: sgs(E) for 181Ta(g,n)180Tags Photoactivation

18 sgs(E):partial cross section for the ground state
181Ta(g,n)180Tags(EC)180Hf Photoactivation 180Hf KX rays

19 Partial cross sections for the isomeric state
: sm(E) for 181Ta(g,n)180Tam Combinatorial NLD: Hilaire et al. 2001: Goriely & Hilaire 2006 HFBCS pot. model: Demetriou & Goriely 2001 stot (E) sm(E) S. Goko et al. Phys. Rev. Lett. May-2006 issue, in press

20 Partial neutron capture cross section
179Ta(n,g)180Tam sm = 90 ± 22 mb at 30 keV: Statistical Model Calculation with the combinatorial NLD Previously, sm = 44 mb

21 Conclusions Astrophysical photo-reactions and disintegrations (APHRODITE) constitute an important research field in connection with the origin of heavy elements by probing ・E1 g strength function above/below neutron thresholds ・nuclear level density The following three research activities are important: (1) Photonuclear reaction experiments (g,n) (g,p) (g,a) (g,g’) (2) Nuclear theory and astrophysical modeling (3) New photon sources in the MeV region

22 10 tesla Super-Conducting Wiggler
Yonehara, Soutome & Kumagai SPring-8

23 10T- SCW synchrotron radiation
Utsunomiya et al., 2005 NIMA538, 225 Black-body radiation at billions of Kelvin Determination of Laboratory reaction rates for (g,n), (g,p), and (g,a) reactions


Download ppt "Photonuclear reactions in astrophysics"

Similar presentations


Ads by Google