H/He burning reactions on unstable nuclei for Nuclear Astrophysics

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1 H/He burning reactions on unstable nuclei for Nuclear Astrophysics PJ Woods University of Edinburgh H T O F E E U D N I I N V E B R U S I R T Y H G

2 Explosive H/He burning in Binary Stars Isaac Newton, Principia Mathematica (1666): from this fresh supply of new fuel those old stars, acquiring new splendour, may pass for new stars

3 J. José, M. Hernanz, C. Iliadis. Nucl Phys A, 777, (2006), Elemental abundances in novae ejecta 1.35 M Sun ONe nova

4 Presolar grains o Grains of nova origin are thought to have a large 30 Si/ 28 Si ratio. o Abundance of 30 Si is determined by the competition between the 30 P β + decay and the 30 P(p,γ) 31 S reaction rate. Andrew M Davis. University of Chicago

5 Novae Nucleosynthesis (p,γ) 31 Cl 32 Cl 33 Cl 34 Cl β + (γ,p) 30 S 31 S 32 S 33 S 27 P 28 P 29 P 31 P 30 P 26 Si 27 Si 28 Si 29 Si 30 Si

6 Sensitivity to uncertainty in 30 P(p,γ) 31 S reaction rate Relative change in abundance 30 P(p,γ) 31 S Mass number C. Iliadis, A. Champagne, J José et al., Astrophys. J. Suppl. Ser. 142, 105 (2002)

7 H/He burning reactions at stellar energies Maxwell-Boltzmann distribution exp(-e/kt) tunnelling through Coulomb barrier exp ' ( k / E ) relative probability Gamow peak ΔE 0 kt E 0 energy Reaction rate often dominated by a few resonances in Gamow burning window

8 Known 31 S level scheme o States populated by 20 Ne( 12 C,n) 31 S 31 S proton threshold D.G. Jenkins et al, Phys. Rev. C. 72. (2005)

9 4 He + 28 Si à 31 S + n fusion reaction

10 Pairing of new levels with analog states in mirror nucleus

11 30 P(p,γ) 31 S reaction rate using new resonance data However, key resonance strengths, ω γ, based on systematic values for proton spectroscopic factors

12 ωγ = (2J 1 2J R )(2J 2 + 1) Γ p Γ Γ tot γ use transfer reactions to estimate Г p for (p,γ) reactions where resonance has Г p << Г γ, ω γ is proportional to Г p. Г p α P l (barrier penetration factor) X S(spectroscopic factor) σ transfer = σ DWBA X S

13 P.J. Woods, A Kankainen, H. Schatz, et al. (d,n) transfer reaction cross-section measurements as a surrogate for (p,γ) secondary 30 MeV/u 30 P ions GRETINA Target CD2 ~ 10 mg/cm 2 CH2 (background) Be ~1900 mg/cm 2 Al 450/600 mg/cm 2 Primary beam: 150 MeV/u 36 Ar 18+

14 Particle identification: 31 S 30P 31 S

15 31 S γ-ray energy spectrum 5143 kev CD2 CH kev

16 Levels above the proton threshold energy in 31 S T=0.6 GK P + p 5/2 + 3/ T=0.4 GK T=0.2 GK T=0.1 GK Sp=6130.9(4) kev 31 S Calculations of extracted Γ p values from cross-section data being performed by F Nunes (MSU)

17 Galactic abundance distribution of the cosmic γ-ray emitter 26 Al INTEGRAL satellite telescope - 2.8(8) M sun of 26 Al in our galaxy [R. Diehl, Nature (2006)]

18 Supernova Cycle

19 Stellar Life

20 Mg-Al Cycle Hydrogen burning in Mg Al Cycle Si Si Si Al Al Al 6s 1Myr Mg Mg Mg

21

22 MD1 ED1 Direct measurement of 26g Al(p,γ) 27 Si reaction on 189 kev resonance, PRL (2006) à lower energy resonances may dominate destruction of 26 Al burning in massive stars?

23 Factor ~ 10 4 reduction in uncertainties in estimated 26g Al(p,γ )27 Si reaction rate 10 8 K However, resonance strengths for critical low T 26 Al burning regime in Wolf-Rayet stars still need to be determined

24 High resolution d( 26g Al,p) 27 Al study of analog states of 27 Si resonances using Edinburgh TUDA Si Triumf 150 MeV 26g Al à (CD 2 ) n target I beam ~ 5*10 8 pps proton 0 à increasing excitation energy Astrophysically Important Region

25 7175 9/ / / /2 + Key analog states / / / /2 9/ /2 + à Lower energy resonance strength much higher than expected?

26 The 15 O(α,γ) 19 Ne reaction: the nuclear trigger of X-ray bursts Reaction regulates flow between the hot CNO cycles and rp process à critical for explanation of amplitude and periodicity of bursts

27 The Hot CNO Cycles

28 15 O(α,γ) 19 Ne reaction rate predicted to be dominated by a single resonance at a CoM energy of 504 kev Key unknown - α-decay probability from excited state at 4.03 MeV in 19 Ne compared to γ-decay, predicted to be ~ 10-4

29 p( 21 Ne, 3 H) 19 Ne* Background produced by reactions of 21 Ne beam with 12 C in target <

30 Study of the p( 20 Ne, 2 H) 19 Ne transfer reacuon on the ESR heavy ion storage PJW, Y Litvinov et al. 8 m Ne 50 MeV/u ESR Electron cooler H 2 /cm 2 gas target

31 Detector Pocket Si telescope 2 x ~1mm W - type detectors 16x16 strips

32 Particle ID plot for DSSD ΔE1 d fast α s p E1 + E2

33 DT Doherty, PhD Thesis (2014) A few hours of data from test run on ESR

34 Injection of RIBs into ring at MeV/u energies Spokesperson: K Blaum (Heidelberg) Deputies: R Raabe(Leuven), PJW (Edinburgh) entire issue of EPJ (2012)

35 ISOLDE site (west) side 23.3m 24.6m Proposed layout to fit the TSR at the west side: - Installation above the CERN infrastructure-tunnel 3m 35

36 Future 26m AI(d,p) 27 Al study on TSR storage In-ring target chamber & heavy-ion recoil detection system in UHV isomer can be excited in core collapse supernovae - influences extinct 26 Al observed in meteorites as excess 26 Mg

37 In-ring DSSD System for ultra-high resolution (d,p), (p,d) and ( 3 He,d) transfer studies of astrophysical resonances à Newly funded UK ISOL-SRS project (Spokesperson PJW) For ultra high resolution mode resolution should be entirely limited by transverse beam emittance à resolutions approaching 10 kev FWHM attainable

38 Pioneering new technique on ESR (Heil, Reifarth) heavy recoils detected with double-sided silicon strip detector (Edinburgh) Particle detectors Position distribution of recoiling ions measured by DSSD Gas jet σ 96Ru(p,γ)= 3.6(5) ~10 MeV/u New DSSD system developed (Edinburgh/GSI/Frankfurt) for p-process capture reactions in Gamow burning window à CRYRING@GSI

39 Puzzle of the origin of heavy p-nuclei abundant proton-rich isotopes eg 92 Mo and 96 Ru Supernova shock passing through O-Ne layers of progenitor star

40 Summary We are entering an exciting phase of development combining a variety of different experimental approaches to determine key H/He burning reaction rates for explosive astrophysical scenarios such as Novae, Supernovae and X-ray bursts.