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Measurement of the 26 Al(d,p) 27 Al reaction to constrain the 26 Al(p, g ) 27 Si reaction rate

Measurement of the 26 Al(d,p) 27 Al reaction to constrain the 26 Al(p, g ) 27 Si reaction rate. Steven D. Pain Oak Ridge National Laboratory. Astrophysical significance of 26 Al Previous measurements 26 Al(d,p) measurement. NS12, Argonne, 2012. 26 Al - Background.

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Measurement of the 26 Al(d,p) 27 Al reaction to constrain the 26 Al(p, g ) 27 Si reaction rate

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  1. Measurement of the 26Al(d,p)27Al reaction to constrain the 26Al(p,g)27Si reaction rate Steven D. Pain Oak Ridge National Laboratory • Astrophysical significance of 26Al • Previous measurements • 26Al(d,p) measurement NS12, Argonne, 2012

  2. 26Al - Background • 26Al nucleus was the first radioisotope detected in the interstellar medium • Half life of 7.2x105 years • Observation of g rays associated with its decay provides evidence of nucleosynthesis • Temperatures ≥ 0.03 GK, the 26gAl(p,g)27Si reaction is expected to contribute to the destruction of 26Al N. Prantzos, R. Diehl. Physics Reports 267 1-69 (1996) 5+ gs, 0+ isomeric state at 228 keV

  3. 26Al - Background • Core-collapse supernovae • Novae • Massive stars (WR, AGB) massive star collapses Tc ~ 3 GK long favored source accretion onto a white dwarf estimated < 0.4 MO26Al ejected – depends on uncertain reactions T < 0.4 GK >30 MO stars – develop strong stellar winds blowing material into space T < 0.1 GK N. Prantzos, R. Diehl. Physics Reports 267 1-69 (1996) 5+ gs, 0+ isomeric state at 228 keV constrain 26Al(p,g) rates for massive stars

  4. 26Al – Early inference First inference of ongoing 26Al synthesis February 8, 1969 Several tons of material deposited Material dated to predate formation of the Earth Excess of 26Mg found in calcium and aluminium inclusions of the Allende meteorite Allende

  5. 26Al – Early observation First astronomical observation of 26Al HEAO (High Energy Astronomy Observatory) Largest germanium spectrometer placed in orbit at that time High Resolution Gamma Ray Spectrometer (HRGRS): 50 keV - 10 MeV 3 keV resolution FOV 30° 1979-1981 Four p-type Ge detectors CsI anti-coincidence

  6. 26Al – Astronomical mapping Compton Gamma Ray Observatory - COMPTEL Energy resolution 5 - 8% (FWHM) Angular resolution 1.7 - 4.4 degrees (FWHM) Launched 1991 NE 213A NaI Weight: 1460 kg Dimensions: 2.61 m x 1.76 m diameter Power: 206 W young giant stars

  7. INTEGRAL Energy resolution (FWHM): 2.2 keV at 1.33 MeV for each detector (3 keV for the entire spectrometer) Angular resolution 2.5° for point sources 19 Ge detectors Field of View fully coded: 14° flat to flat, 16° corner to corner Launched October 2002

  8. Galactic presence of 26Al Line width dominated by instrumental resolution SPI (INTEGRAL) Doppler shifts suggest 26Al is co-rotating with the Galaxy

  9. Astrophysically Important States Lotay et al., PRL 102, 162502 (2009) 508 429 368 0.1 1 T(GK) 332 276 241 231 189 127 94 68 6

  10. Astrophysically Important States – proton transfer study Vogelaar et al, PRC 53 1945 (1996) 127 keV 26Al(3He,d)27Si Isotopically enriched target (6.3% 26Al/27Al) Upper limit on 127 keV resonance (S<0.02) 189 keV 276 keV

  11. Identification of mirror states in 27Al G. Lotay et al, PRL 102 162502 (2009) • Fusion-evaporation reaction to populate states and studyγdecays with Gammasphere • 6 pnA, 26 MeV beam of 16O ions on ~150μg/cm² 12C target • Location of low-lying resonances constrained stellar rate, assuming: • 0.001 < S < 0.02 (Vogelaar upper limit) for 127 keV • 0.01 < S < 0.3 for 68 keV resonance • S for these states necessary for further constraint on the reaction rate lowest direct (p,g) measurement C. Ruiz et al., PRL 96 252501 (2006)

  12. Identification of mirror states in 27Al 0.1 1 T(GK) G. Lotay et al, PRL 102 162502 (2009) AGB + WR stars lowest direct (p,g) measurement C. Ruiz et al., PRL 96 252501 (2006)

  13. 26Al(d,p)27Al data – Setup 15 10 10 5 5 90 45 60 75 100 130 115 • 117 MeV 26Al • 5x106 pps • 150 mg/cm2 CD2 • MCP normalization (200 kHz) QQQ stack SIDAR MCPs ORRUBA 5 12C d 2.5 p 135 165 150

  14. 26Al(d,p)27Al – Excitation Energy 165 deg 138 deg 75 keV (CoM) 180 keV (CoM) 1 2 3 4 5 6 7 8 9 10 Ex(MeV)

  15. 26Al(d,p)27Al – Excitation Energy ℓp = 0 Astro 164 deg 138 deg 75 keV (CoM) 180 keV (CoM) 1 2 3 4 5 6 7 8 9 10 Ex(MeV)

  16. 26Al(d,p)27Al – carbon background PRELIMINARY ~145° ~164° Run on carbon foil to determine form of background from reactions on carbon

  17. 26Al(d,p)27Al – magnesium contamination PRELIMINARY ~145° ~164° Astro Astro Run with 26Mg beam (5+) to determine background peaks from reactions 26Mg(d,p)

  18. 26Al(d,p)27Al – Background subtracted excitation energy PRELIMINARY FWHM ~ 75 keV (CoM) 5550 keV 11/2+ 3004 keV (9/2+) 6948 keV 11/2+ 4510 keV (11/2+) 1 2 3 4 5 6 7 8 9 10 Ex(MeV)

  19. 26Al(d,p)27Al – Excitation Energy 7858 7806 7798 7721 PRELIMINARY NNDC FWHM ~ 75 keV (CoM) 3/2+ 9/2+ (3/2, 5/2, 7/2) 5/2 7804(12) keV 127 keV mirror? 1 2 3 4 5 6 7 8 9 10 Ex(MeV)

  20. 26Al(d,p)27Al – Excitation Energy PRELIMINARY FWHM ~ 75 keV (CoM) S = 0.018(6) 7804(12) keV 127 keV mirror 1 2 3 4 5 6 7 8 9 10 Ex(MeV)

  21. 26Al(d,p)27Al – Excitation Energy Lotay et al., PRL 102, 162502 (2009) 0.1 1 T(GK) PRELIMINARY FWHM ~ 75 keV (CoM) 7804(12) keV 127 keV mirror 1 2 3 4 5 6 7 8 9 10 Ex(MeV)

  22. 26Al(d,p)27Al – Excitation Energy Lotay et al., PRL 102, 162502 (2009) 0.1 1 T(GK) PRELIMINARY 164 deg 75 keV (CoM) 150 keV (CoM) 132.5 deg 68 keV mirror 68 keV mirror 1 2 3 4 5 6 7 8 9 10 Ex(MeV)

  23. 26Al is the first radioisotope to have a high-resolution Galactic map Resonances in nova(+) Gamow windows measured directly Understanding the structure of low-lying resonances is important for constraining the 26Al(p,g)27Si rate in massive stars Measured single-particle strengths of mirror levels via 26Al(d,p) for constraining stellar reaction rate Population of mirror to the 127 keV ℓ = 0 resonance (preliminary2) S ~ 0.018(6) - comparable to upper limit set by (3He,d) measurement (S < 0.02) Mirror calculations (Marek Ploszajczak, GANIL) Further analysis required to constrain ℓ = 2 state at angles closer to 90 deg; 68 keV mirror is very weakly populated Summary

  24. Collaborators D.W. Bardayan, C.D. Nesaraja, M.S. Smith, D. Shapira, F. Liang Oak Ridge National Laboratory K.Y. Chae, K.L. Jones, S.T. Pittman, K.T. Schmitt University of Tennessee K.A. Chipps J.A. Cizewski, P.D. O’Malley, S. Hardy Rutgers University C. Matei, W.A. Peters Oak Ridge Associated Universities R.L. Kozub, J.F. Shriner Tennessee Tech. University J.C. Blackmon, M. Matos Louisiana State University P.D. Parker Louisiana State University G.L. Wilson University of Surrey

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