The statistical properties of 92 Mo and implications for the p-process

Transcription

1 The statistical properties of 9 Mo and implications for the p-process G.M. Tveten g.m.tveten@fys.uio.no Department of Physics University of Oslo INPC01 - G. M. Tveten 1

2 G Sites of production? INPC01 - G. M. Tveten Type Supernova or type 1a Supernova dit: X-ray: NASA/CXC/Penn State/S.Park et al.; Optical: Pal.Obs. P-nuclei are stable, proton-rich isotopes that are bypassed by the s- and r-process

3 G Where does all the come from? Sites of production? INPC01 - G. M. Tveten Type Supernova or type 1a Supernova dit: X-ray: NASA/CXC/Penn State/S.Park et al.; Optical: Pal.Obs. P-nuclei are stable, proton-rich isotopes that are bypassed by the s- and r-process

4 Rapp et al., The Astrophysical Journal, 7 (00) 9 Mo is underproduced in calculations compared to solar abundances <F i >/F 0 Mass number If <F i >/F 0 = 1 the value matches solar abundance INPC01 - G. M. Tveten

5 Rapp et al., The Astrophysical Journal, 7 (00) 9 Mo is underproduced in calculations compared to solar abundances <F i >/F 0 Mass number If <F i >/F 0 = 1 the value matches solar abundance Experimentally unknown INPC01 - G. M. Tveten

6 Idea: Use γ strength function (GSF) and nuclear level density (NLD) to constrain cross section GSF NLD OMP Cross sec(on of 91 Nb(p,γ) 9 Mo INPC01 - G. M. Tveten

7 Setup at the Oslo cyclotron laboratory SiRi + CACTUS 1. MeV proton beam from our cyclotron Details SiRi: Guttormsen et al. arxiv:1.189 [nucl-ex] 8x8 segmented Si-array at backwards angles 1 o -10 o x NaI(Tl) collimated scintillator detectors INPC01 - G. M. Tveten 7

8 The Oslo method Oslo method Particle-γ coincidences from 9 Mo(p,p γ) INPC01 - G. M. Tveten 8

9 The Oslo method Oslo method 1. Unfolding Particle-γ coincidences from 9 Mo(p,p γ) INPC01 - G. M. Tveten 9

10 The Oslo method Oslo method Excitation energy Ex (MeV) 1 1. Unfolding. Extract primary γ s P(E i, E γ ) T (E γ ) ρ (E f ) γ -ray energy Eγ (MeV) Particle-γ coincidences from 9Mo(p,p γ) INPC01 - G. M. Tveten 1

11 The Oslo method Oslo method ) -1 ρ (E) (MeV Level density 1 Oslo data Known levels CT or FG model ρ from neutron res. data xx Yy NLD Particle-γ coincidences from 9 Mo(p,p γ) 1. Unfolding. First generation method. Simultaneous extraction of NLD Excitation energy E (MeV) INPC01 - G. M. Tveten 11

12 The Oslo method Particle-γ coincidences from 9 Mo(p,p γ) Oslo method 1. Unfolding ) -1 ρ (E) (MeV Level density. First generation method. Simultaneous extraction of NLD and GSF 1 1 Oslo data Known levels CT or FG model ρ from neutron res. data GSF xx Yy NLD Excitation energy E (MeV) INPC01 - G. M. Tveten 1

13 The Oslo method Particle-γ coincidences from 9 Mo(p,p γ) Oslo method 1. Unfolding ) -1 ρ (E) (MeV Level density. First generation method. Simultaneous extraction of NLD and GSF 1 1 Oslo data Known levels CT or FG model ρ from neutron res. data GSF xx Yy NLD Excitation energy E (MeV). Normalization! INPC01 - G. M. Tveten 1

14 Oslo data Known levels CT model ρ from systematics 9 Mo -1 NLD ρ (E) (MeV -1 ) (MeV) E x Excitation energy (MeV) INPC01 - G. M. Tveten 1

15 Oslo data Known levels CT model ρ from systematics 9 Mo -1 NLD ρ (E) (MeV -1 ) (MeV) E x Excitation energy (MeV) Low excitation: We count known levels INPC01 - G. M. Tveten 1

16 Oslo data Known levels CT model ρ from systematics 9 Mo High excitation energy: We calculate from average level spacings at S n -1 NLD ρ (E) (MeV -1 ) For 9 Mo we estimated from systematics (MeV) E x Excitation energy (MeV) Low excitation: We count known levels INPC01 - G. M. Tveten 1

17 Oslo data Known levels CT model ρ from systematics 9 Mo High excitation energy: We calculate from average level spacings at S n -1 NLD ρ (E) (MeV -1 ) For 9 Mo we estimated from systematics (MeV) E x Excitation energy (MeV) Low excitation: We count known levels INPC01 - G. M. Tveten 17

18 ) - ) (MeV γ f(e OCL data Mo 9 OCL data Mo 9,9,9 Utsunomiya et al. Mo(γ,n) 9,9 Beil et al. Mo(γ,n) 9 Beil et al. Mo(γ,n) 9 Mo(γ,γ ) γsf-model Here too, we needed to rely on systematics. Are we able to connect with existing data above S n? γ-ray energy E (MeV) INPC01 - G. M. Tveten 18 γ

19 ) - ) (MeV γ 9 OCL data Mo 9 OCL data Mo Here too, we needed to rely on systematics. 7 9,9,9 Utsunomiya et al. Mo(γ,n) 9,9 Beil et al. Mo(γ,n) 9 Beil et al. Mo(γ,n) 9 Mo(γ,γ ) γsf-model 9 Mo Are we able to connect with existing data above S n? f(e 8 Sn=1.7 MeV γ-ray energy E (MeV) INPC01 - G. M. Tveten 19 γ

20 The (p,g) cross section and (p,g) and (g,p) Maxwellian averaged reaction rates were calculated using TALYS Input: NLD and GSF models based on the experimental results s -1 ) -1 mol <σν> (cm Present TALYS upper limit TALYS lower limit JINA-REACLIB BRUSLIB T (GK) INPC01 - G. M. Tveten 0

21 Nuclear reaction network calculations for 1 layers (as in the sensitivity study by Rapp et al.00) M star O-Ne layers NucNet Tools Cumulative mass fraction Nb(p,γ) Mo ± factor 91 9 Nb(p,γ) Mo - present work Tveten et al. PRC 9, 080 (01) arxiv: Layer max T (GK). INPC01 - G. M. Tveten 1 1.8

22 Collaborators, thanks! Questions? INPC01 - G. M. Tveten

23 So, does it work? Probability Probability(%) (%)/ch / ch 8 P(Ei, Eγ ) 8 Probability(%) / ch 7 (a) Ex = 7.18 MeV (b) Ex = 7.1 MeV (c) Ex = 8.0 MeV Primary data ρt (d) Ex = 8.80 MeV (e) Ex = 9. MeV (f) Ex =. MeV Probability / ch 1 Excitation energy (MeV) x P(E i, E γ ) T (E γ ) ρ (E f ) γ -ray energy Eγ (MeV) γ-ray energy (MeV) INPC01 - G. M. Tveten Eγ (kev) γ-ray energy (MeV) 9

24 INPC01 - G. M. Tveten

25 λ = π M if ρ(e f ) P(E i, E γ ) T (E γ ) ρ(e f ) INPC01 - G. M. Tveten