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

26 Al - Background 26 Al nucleus was the first radioisotope detected in the interstellar medium Half life of 7.2x10 5 years Observation of  rays associated with its decay provides evidence of nucleosynthesis Temperatures ≥ 0.03 GK, the 26g Al(p,  ) 27 Si reaction is expected to contribute to the destruction of 26 Al N. Prantzos, R. Diehl. Physics Reports (1996) 5 + gs, 0 + isomeric state at 228 keV

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

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

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

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

INTEGRAL Launched October 2002 Field of View fully coded: 14° flat to flat, 16° corner to corner 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

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

Astrophysically Important States T(GK) Lotay et al., PRL 102, (2009)

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

Identification of mirror states in 27 Al Fusion-evaporation reaction to populate states and study γ decays with Gammasphere 6 pnA, 26 MeV beam of 16 O ions on ~150 μ g/cm² 12 C 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 27 Si 27 Al E res (keV)E ex JJ / / / / / / / / /2 - lowest direct (p,  ) measurement C. Ruiz et al., PRL (2006) G. Lotay et al, PRL (2009)

Identification of mirror states in 27 Al 27 Si 27 Al E res (keV)E ex JJ / / / / / / / / /2 - G. Lotay et al, PRL (2009) lowest direct (p,  ) measurement C. Ruiz et al., PRL (2006) 0.11T(GK) AGB + WR stars

26 Al(d,p) 27 Al data – Setup 117 MeV 26 Al 5x10 6 pps 150  g/cm 2 CD 2 MCP normalization (200 kHz) QQQ stack ORRUBA SIDAR C d p MCPs

26 Al(d,p) 27 Al – Excitation Energy E x (MeV) 165 deg 138 deg 75 keV (CoM) 180 keV (CoM)

26 Al(d,p) 27 Al – Excitation Energy E x (MeV) 164 deg 138 deg ℓ p = 0 75 keV (CoM) 180 keV (CoM) Astro

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

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

26 Al(d,p) 27 Al – Background subtracted excitation energy E x (MeV) 3004 keV (9/2 + ) PRELIMINARY FWHM ~ 75 keV (CoM) 4510 keV (11/2 + ) 5550 keV 11/ keV 11/2 +

26 Al(d,p) 27 Al – Excitation Energy E x (MeV) PRELIMINARY /2 + 9/2 + (3/2, 5/2, 7/2) 5/2 FWHM ~ 75 keV (CoM) 7804(12) keV 127 keV mirror? NNDC

26 Al(d,p) 27 Al – Excitation Energy E x (MeV) FWHM ~ 75 keV (CoM) PRELIMINARY S = 0.018(6) 7804(12) keV 127 keV mirror

26 Al(d,p) 27 Al – Excitation Energy E x (MeV) FWHM ~ 75 keV (CoM) PRELIMINARY 0.11T(GK) Lotay et al., PRL 102, (2009) 7804(12) keV 127 keV mirror

26 Al(d,p) 27 Al – Excitation Energy PRELIMINARY 68 keV mirror E x (MeV) 68 keV mirror 164 deg deg 75 keV (CoM) 150 keV (CoM) 0.11T(GK) Lotay et al., PRL 102, (2009)

26 Al 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 26 Al(p,  ) 27 Si rate in massive stars Measured single-particle strengths of mirror levels via 26 Al(d,p) for constraining stellar reaction rate –Population of mirror to the 127 keV ℓ = 0 resonance –(preliminary 2 ) S ~ 0.018(6) - comparable to upper limit set by ( 3 He,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 populatedSummary

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 Collaborators