JINA Frontiers 2005 Lifetimes of the astrophysically important states in 19 Ne Wanpeng Tan University of Notre Dame Collaborators: J. Görres, M. Wiescher, J. Daly, M. Couder, A. Couture, H.Y. Lee, E. Stech, E. Strandberg, and C. Ugalde

JINA Frontiers 2005 Motivation is one of the two routes to break out CNO cycles and trigger rp- process 15 O( ,  ) 19 Ne is one of the two routes to break out CNO cycles and trigger rp- process –Energy production –Nucleosynthesis X-ray bursts: s, erg Superbursts: 1000x stronger and longer Wiescher et al., J. Phys. G 25, R133 (1999) Fisker et al., astro-ph/ (2005) 4U Rossi X-ray Timing Explorer Picture: T. Strohmeyer, GSFC Superburst 4U Picture: T. Strohmayer, GSFC

JINA Frontiers 2005 Breakout of the Hot CNO Cycles T 9 <0.08 Cold CNO cycles T 9 <0.3 Hot CNO cycles T 9 > , breakout leads to the rp-process Two routes: 15 O( ,  ) 19 Ne 18 Ne( ,p) 21 Na

JINA Frontiers 2005 The importance of 4.03MeV state of 19Ne Reaction rate of resonances Three quantities for nuclear physicists to measure: E R, Γ γ, B α besides J Γ γ of α-unbound states of 19Ne are unmeasured MeV level dominates the rate at temperatures T 9 < 0.6. –Very small B α <4.3x10 -4 by Davids et al, PRC2003 –Only upper/lower limits on lifetime τ<50fs by Davidson et al, NPA1973 Γ<440 meV by Hackman et al, PRC2000 T9T9 4.03MeV 4.55MeV 4.71MeV 4.38MeV 4.60MeV ωγfrom Langanke et al, Ap. J. 301, 629(1986)

JINA Frontiers 2005 Doppler-Shift Attenuation Method (DSAM) Measure lifetime to obtain decay width Traditional method –Easy to apply and good for poorly resolved peaks –Not sufficient for asymmetric peaks and feeding effects from higher lying states Full line shape analysis –Realistic Geant4 simulation –Details of the peak shape, especially for double peak structure and tailing effects –Dealing with the feeding from higher lying states γ 19Ne target

JINA Frontiers O( 3 He,n-γ) 19 Ne maximize Doppler shift of gamma energies by measuring gammas emitted along the same direction as 19 Ne travels. => lifetime measurement 3 He 3MeV 17O/Ta n det HPGe 3 He 3MeV 17O/Ta n det HPGe 28.5 o 45 o 135 o 90 o Doppler shifts and geometry uncertainty are cancelled. => energy measurement

JINA Frontiers o 0o0o 135 o Gamma peaks are not only shifted but also broadened. Simple DSAM approach is insufficient to study more complicated shapes Full line-shape analysis is necessary for precise measurements –Details of the peak shape, especially for double peak structure and tailing effects –Dealing with the feeding from higher lying states 19 Ne related gamma spectra in coincidence with neutrons

JINA Frontiers 2005 Unshifted 4034keV state Measured Ex = ±0.8 keV

JINA Frontiers keV state of 19 Ne Best Geant4 fit 2sigma uncertainties Upper limit by Davidson et al 13 fs 4 fs 29 fs 50 fs Measured lifetime τ = 13± 9 6 fs or Γ=51± meV

JINA Frontiers 2005 Errors of mean lifetimes of present work are given at the 95% confidence level. Compilation (TUNL) Present work E* [keV] JπJπJπJπ τ m [fs] E*[keV] ±0.3 5/ ± ±0.4x ±0.4x ±0.4 3/2+ 28± ± ±6 16 ± ±0.5 3/ ± ± ±25 80 ± ±0.6 9/ ± ± ± ±2.4 3/2+< ± ±4 (9/2)-< ± ±2.4 (7/2)-< ± ±2.2 7/2+< ± ±4 (1/2,3/2)-< ± ±4 (5/2+)< ± ±4 13/2+ >1x ±0.9 >1x10 3 Summary of our results