TRIUMF Canada’s national laboratory for nuclear and particle physics Direct Measurement of the 21 Na(p,γ) 22 Mg 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

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

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

23 July 2004 NIC8 – Direct measurement of the 21 Na(p,γ) 22 Mg reaction: Resonance strengths and γ-γ analysis 4 DRAGON Facility D. Hutcheon et al., NIM A 498, 190 (2003).

23 July 2004 NIC8 – Direct measurement of the 21 Na(p,γ) 22 Mg reaction: Resonance strengths and γ-γ analysis 5 DRAGON Programme Almost completedAlmost completed – 21 Na(p,γ) 22 Mg In progressIn progress – 26 Al(p,γ) 27 Si – 12 C(α,γ) 16 O – 12 C( 12 C,γ) 24 Mg Future workFuture work – 26m Al(p,γ) 27 Si – 25 Al(p,γ) 26 Si

23 July 2004 NIC8 – Direct measurement of the 21 Na(p,γ) 22 Mg reaction: Resonance strengths and γ-γ analysis 6 21 Na(p,γ) 22 Mg Reaction S. Bishop et al., PRL 90, (2003). First direct radioactive beam measurement of the reaction rate, populating the MeV level in 22 MgFirst direct radioactive beam measurement of the reaction rate, populating the MeV level in 22 Mg Measured resonance energy and the resonance strengthMeasured resonance energy and the resonance strength –E cm = ± 0.5 keV –ωγ = 1.03 ± 0.21 meV

23 July 2004 NIC8 – Direct measurement of the 21 Na(p,γ) 22 Mg 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 22 Na production in ONe novae and x-ray burstsExtended the measurements to other states, deduced their contributions to the reaction rate and their impact on 22 Na production in ONe novae and x-ray bursts J.M. D’Auria et al., PRC 69, (2004).

23 July 2004 NIC8 – Direct measurement of the 21 Na(p,γ) 22 Mg reaction: Resonance strengths and γ-γ analysis 8 Summary of 21 Na(p,γ) 22 Mg E x (keV) E cm (keV) Γ (keV) ωγ (meV) ± ± ≤ 0.29 ≤ ± ± ± ± ± ± ± ± ± ± ± ± 62 J.M. D’Auria et al., PRC 69, (2004). Resonance Strengths and Energies

23 July 2004 NIC8 – Direct measurement of the 21 Na(p,γ) 22 Mg reaction: Resonance strengths and γ-γ analysis 9 BGO Array D.G. Gigliotti et al., NIM B 204, 671 (2003). D.G. Gigliotti, M.Sc. thesis, University of Northern BC. Efficiency MeV gammasEfficiency MeV gammas –60-72% (0.5 MeV threshold) –45-60% full Geant simulation FWHM at 6.13 MeV ( 244 Cm/ 13 C)FWHM at 6.13 MeV ( 244 Cm/ 13 C) –Averages 7% for all detectors

23 July 2004 NIC8 – Direct measurement of the 21 Na(p,γ) 22 Mg reaction: Resonance strengths and γ-γ analysis 10 γ-γ Correlation Analysis Received Na per second from ISAC onto H 2 gas targetReceived Na per second from ISAC onto H 2 gas target Detect multiple gammas in the BGO arrayDetect multiple gammas in the BGO array Propose decays and spin assignments, guided by analogue states in the mirror nucleus 22 NePropose decays and spin assignments, guided by analogue states in the mirror nucleus 22 Ne Future: working on using our GEANT simulation to possibly extract branching ratiosFuture: working on using our GEANT simulation to possibly extract branching ratios C.C. Jewett, Ph.D. thesis, Colorado School of Mines.

23 July 2004 NIC8 – Direct measurement of the 21 Na(p,γ) 22 Mg reaction: Resonance strengths and γ-γ analysis keV Resonance

23 July 2004 NIC8 – Direct measurement of the 21 Na(p,γ) 22 Mg reaction: Resonance strengths and γ-γ analysis 12 The three Resonances

23 July 2004 NIC8 – Direct measurement of the 21 Na(p,γ) 22 Mg reaction: Resonance strengths and γ-γ analysis 13 Revisiting the 1101 keV resonance Different gamma distribution at the low-energy tailDifferent gamma distribution at the low-energy tail TUDA suggested ~1080 keVTUDA suggested ~1080 keV Extended our measurements down to lower energyExtended our measurements down to lower energy –See resonance –Twice as intense C.C. Jewett, Ph.D. thesis, Colorado School of Mines.

23 July 2004 NIC8 – Direct measurement of the 21 Na(p,γ) 22 Mg reaction: Resonance strengths and γ-γ analysis Mg γ-γ Analysis Results 22 Mg Mirror Nucleus 22 Ne b E x (keV) a Level (kev) Proposed J π Level (keV) JπJπJπJπ ± ± ± ~ a J.M. D’Auria et al., PRC 69, (2004). b R.B. Firestone, Table of Isotopes, 8 th Edition, Consistent with results from the TUDA group: C. Ruiz et al., PRC 65, (R) (2002). C. Ruiz, Ph.D. Thesis, University of Edinburgh (2003).

23 July 2004 NIC8 – Direct measurement of the 21 Na(p,γ) 22 Mg reaction: Resonance strengths and γ-γ analysis Al(p,γ) 27 Si keV resonance 7652 keV level7652 keV level Dominating resonance in 26 Al+p for novaeDominating resonance in 26 Al+p for novae A change in ωγ by 1/3 would change the final abundance of 26 Al by a factor of 2A change in ωγ by 1/3 would change the final abundance of 26 Al by a factor of 2 Weak, poorly-known resonanceWeak, poorly-known resonance –High 0.29 meV –Low meV –Adopted value meV DRAGON will use the 7828 keV level (363 keV resonance) for commissioningDRAGON will use the 7828 keV level (363 keV resonance) for commissioning

23 July 2004 NIC8 – Direct measurement of the 21 Na(p,γ) 22 Mg reaction: Resonance strengths and γ-γ analysis Al(p,γ) 27 Si - Commissioning 363 keV resonance363 keV resonance SiC target optimized for 26 AlSiC target optimized for 26 Al –10 8 per second –1: m Al –1: Na Preliminary ωγ 60 ±14 meVPreliminary ωγ 60 ±14 meV –cf. 65 ±18 meV 26 Al(p,  ) 27 Si 363 keV 27 Si recoils L. Buchmann et al., NPA 415, 93 (1984).

23 July 2004 NIC8 – Direct measurement of the 21 Na(p,γ) 22 Mg reaction: Resonance strengths and γ-γ analysis 17Summary DRAGON is a working facilityDRAGON is a working facility (Almost) Completed 21 Na(p,γ) 22 Mg(Almost) Completed 21 Na(p,γ) 22 Mg –Extending to γ - γ Analysis Stable beams programmeStable beams programme – 12 C(α,γ) 16 O – 12 C( 12 C,γ) 24 Mg Beginning 26 Al(p,γ) 27 SiBeginning 26 Al(p,γ) 27 Si Exciting futureExciting future

23 July 2004 NIC8 – Direct measurement of the 21 Na(p,γ) 22 Mg reaction: Resonance strengths and γ-γ analysis 18 DRAGON E824 Collaboration 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) 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 University of Northern BC Dario Gigliotti Ahmed Hussein McMaster University Alan Chen Jonty Pearson Yale University Rachel Lewis Peter Parker Ruhr-Universität, Bochum Sabine Engel Universitat Politécnica de Catalunya Jordi José

23 July 2004 NIC8 – Direct measurement of the 21 Na(p,γ) 22 Mg reaction: Resonance strengths and γ-γ analysis 19