Direct Measurement of the 21 Na(p, γ ) 22 Mg Reaction: Resonance Strengths and γ - γ Analysis

1. Direct Measurement of the 21Na(p,γ)22Mg Reaction: Resonance Strengths and γ-γ Analysis Mike Trinczek for the DRAGON Collaboration TRIUMF Eighth International Symposium on Nuclei in the Cosmos 23 July 2004

2. Outline • DRAGON Facility • 21Na(p,γ)22Mg results • Current and Future work • γ-γ Analysis of 22Mg Levels • 26Al(p,γ)27Si • Summary NIC8 – Direct measurement of the 21Na(p,γ)22Mg reaction: Resonance strengths and γ-γ analysis

3. ISAC: Highest yields for On-Line Facilities, can go up to 100 μA @ 500 MeV DC proton Target-Ion Sources: • Surface  • Li, K, Na, Rb, Al, … • ECR, on-line tests and first experiment  • 18,19Ne • Laser, off-line test  • Ga in the Fall, Al • Negative, off-line test  • FEBIAD prototype  • High-power target tested off-line  • 11Li in Oct. 2004 • Actinide target task force  • Tests in early 2005 NIC8 – Direct measurement of the 21Na(p,γ)22Mg reaction: Resonance strengths and γ-γ analysis

4. DRAGON Facility D. Hutcheon et al., NIM A 498, 190 (2003). NIC8 – Direct measurement of the 21Na(p,γ)22Mg reaction: Resonance strengths and γ-γ analysis

5. DRAGON Programme • Almost completed • 21Na(p,γ)22Mg • In progress • 26Al(p,γ)27Si • 12C(α,γ)16O • 12C(12C,γ)24Mg • Future work • 26mAl(p,γ)27Si • 25Al(p,γ)26Si NIC8 – Direct measurement of the 21Na(p,γ)22Mg reaction: Resonance strengths and γ-γ analysis

6. 21Na(p,γ)22Mg Reaction • First direct radioactive beam measurement of the reaction rate, populating the 5.714 MeV level in 22Mg • Measured resonance energy and the resonance strength • Ecm = 205.7 ± 0.5 keV • ωγ = 1.03 ± 0.21 meV S. Bishop et al., PRL 90, 162501 (2003). NIC8 – Direct measurement of the 21Na(p,γ)22Mg reaction: Resonance strengths and γ-γ analysis

7. Contributions to the Reaction Rate • Extended the measurements to other states, deduced their contributions to the reaction rate and their impact on 22Na production in ONe novae and x-ray bursts J.M. D’Auria et al., PRC 69, 065803 (2004). NIC8 – Direct measurement of the 21Na(p,γ)22Mg reaction: Resonance strengths and γ-γ analysis

8. Summary of 21Na(p,γ)22Mg Resonance Strengths and Energies J.M. D’Auria et al., PRC 69, 065803 (2004). NIC8 – Direct measurement of the 21Na(p,γ)22Mg reaction: Resonance strengths and γ-γ analysis

9. BGO Array • Efficiency 1 - 10 MeV gammas • 60-72% (0.5 MeV threshold) • 45-60% full Geant simulation • FWHM at 6.13 MeV (244Cm/13C) • Averages 7% for all detectors D.G. Gigliotti et al., NIM B 204, 671 (2003). D.G. Gigliotti, M.Sc. thesis, University of Northern BC. NIC8 – Direct measurement of the 21Na(p,γ)22Mg reaction: Resonance strengths and γ-γ analysis

10. γ-γCorrelation Analysis • Received 10921Na per second from ISAC onto H2 gas target • Detect multiple gammas in the BGO array • Propose decays and spin assignments, guided by analogue states in the mirror nucleus 22Ne • Future: working on using our GEANT simulation to possibly extract branching ratios C.C. Jewett, Ph.D. thesis, Colorado School of Mines. NIC8 – Direct measurement of the 21Na(p,γ)22Mg reaction: Resonance strengths and γ-γ analysis

11. 738 keV Resonance NIC8 – Direct measurement of the 21Na(p,γ)22Mg reaction: Resonance strengths and γ-γ analysis

12. The three Resonances NIC8 – Direct measurement of the 21Na(p,γ)22Mg reaction: Resonance strengths and γ-γ analysis

13. Revisiting the 1101 keV resonance • Different gamma distribution at the low-energy tail • TUDA suggested ~1080 keV • Extended our measurements down to lower energy • See resonance • Twice as intense C.C. Jewett, Ph.D. thesis, Colorado School of Mines. NIC8 – Direct measurement of the 21Na(p,γ)22Mg reaction: Resonance strengths and γ-γ analysis

14. 22Mg γ-γ Analysis Results a J.M. D’Auria et al., PRC 69, 065803 (2004). b R.B. Firestone, Table of Isotopes, 8th Edition, 1996. Consistent with results from the TUDA group: C. Ruiz et al., PRC 65, 042801(R) (2002). C. Ruiz, Ph.D. Thesis, University of Edinburgh (2003). NIC8 – Direct measurement of the 21Na(p,γ)22Mg reaction: Resonance strengths and γ-γ analysis

15. 26Al(p,γ)27Si - 188 keV resonance • 7652 keV level • Dominating resonance in 26Al+p for novae • A change in ωγ by 1/3 would change the final abundance of 26Al by a factor of 2 • Weak, poorly-known resonance • High 0.29 meV • Low 10-5 meV • Adopted value 0.064 meV • DRAGON will use the 7828 keV level (363 keV resonance) for commissioning NIC8 – Direct measurement of the 21Na(p,γ)22Mg reaction: Resonance strengths and γ-γ analysis

16. 26Al(p,γ)27Si - Commissioning 26Al(p,g)27Si 363 keV 27Si recoils • 363 keV resonance • SiC target optimized for 26Al • 108 per second • 1:20 000 26mAl • 1:200 26Na • Preliminary ωγ 60 ±14 meV • cf. 65 ±18 meV L. Buchmann et al., NPA 415, 93 (1984). NIC8 – Direct measurement of the 21Na(p,γ)22Mg reaction: Resonance strengths and γ-γ analysis

17. Summary • DRAGON is a working facility • (Almost) Completed 21Na(p,γ)22Mg • Extending to γ-γ Analysis • Stable beams programme • 12C(α,γ)16O • 12C(12C,γ)24Mg • Beginning 26Al(p,γ)27Si • Exciting future NIC8 – Direct measurement of the 21Na(p,γ)22Mg reaction: Resonance strengths and γ-γ analysis

18. DRAGON E824 Collaboration TRIUMF Lothar Buchmann Don Hunter (Langara) Dave Hutcheon Alison Laird (York) Art Olin Dave Ottewell Marcello Pavan Joel Rogers Mike Trinczek Mike Anderson Kathryn Oraas Andres Ruberg Colorado School of Mines Uwe Greife Cybele Jewett Simon Fraser University Shawn Bishop (RIKEN) John D’Auria Mike Lamey (Notre Dame) Chris Ruiz Chris Wrede (Yale) Ruhr-Universität, Bochum Sabine Engel McMaster University Alan Chen Jonty Pearson University of Northern BC Dario Gigliotti Ahmed Hussein Yale University Rachel Lewis Peter Parker Universitat Politécnica de Catalunya Jordi José NIC8 – Direct measurement of the 21Na(p,γ)22Mg reaction: Resonance strengths and γ-γ analysis

19. NIC8 – Direct measurement of the 21Na(p,γ)22Mg reaction: Resonance strengths and γ-γ analysis