1 / 29

Measurements of reactions as found in late stellar burning phases with Dragon

CANADA ’ S NATIONAL LABORATORY FOR PARTICLE AND NUCLEAR PHYSICS. Owned and operated as a joint venture by a consortium of Canadian universities via a contribution through the National Research Council Canada.

rowena
Télécharger la présentation

Measurements of reactions as found in late stellar burning phases with Dragon

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. CANADA’S NATIONAL LABORATORY FOR PARTICLE AND NUCLEAR PHYSICS Owned and operated as a joint venture by a consortium of Canadian universities via a contribution through the National Research Council Canada LABORATOIRE NATIONAL CANADIENPOUR LA RECHERCHE EN PHYSIQUE NUCLÉAIRE ET EN PHYSIQUE DES PARTICULES Propriété d’un consortium d’universités canadiennes, géré en co-entreprise à partir d’une contribution administrée par le Conseil national de recherches Canada Measurements of reactions as found in late stellar burning phases with Dragon Lothar Buchmann TRIUMF and John D’Auria Simon Fraser University

  2. 1984 Key Players: R. Azuma-UT J.K.P. Lee McGill J. Crawford, McGill R. Moore, McGill C. Rolfs, Munster J. King, UT L. Buchmann, UT J. D’Auria, SFU Parksville

  3. ISAC LINACS Energy: 0.15 – 1.5 MeV/u Pulsed Iteration: 86 ns Masses: A < 30 amu (A/q < 30) Built for Astrophysics program

  4. www.triumf.ca/dragon www.triumf.ca/dragon NIM A498(2003)190; A553(2005)491 NIM A498(2003)190 MD1 ED1 DSSD or IC MCP

  5. DRAGON Electrostatic bender Target

  6. DRAGON Quantification • Beam Normalization ( < ± 5% ) - Measured elastic scattering in gas target. - Measured ‘light’ in CCD camera from beam. - Normalized to upstream faraday cup. - Measure charge state distribution of recoil (or same Z). • Beam Energy - Use calibrated NMR probe on MD1 - Calibrated magnet in accelerator line

  7. Features/Performance of DRAGON • All operations are EPICS remotely controlled. • DRAGON is ~21 m long; 1-4 s in flight path depending.. • DRAGON acceptance is <~± 18 mrad; ± 4% in energy • Gas target operates <~ 8 torr (H2 and He). • Special holder used for solid targets. • CSB foil of SiN (50 nm) used to increase aver. Charge. • BGO Gamma Array efficiency ~ 50% depending…. • MD1 used to measure beam energy to ~ 0.15% • RMS limitations: electric rigidity = 8 MV (2E/q); magnetic rigidity = 0.5 T-m [m/q (2E/m)1/2] • RMS accepts only one charge state. • Beam transmission/suppression depends on beam energy; up to 1016 with separator, t-o-f, and  coin. • Focal plane detectors • DSSSD (Double sided, Si strip detector) • Multi-anode Ionization chamber • Both detectors can be operated with a MCP/C foil system for fast signal • A second MCP/C system has been added for improved local T-O-F • Upgrade of electronics has been installed. • Data acquisition by MIDAS; data analysis by several programs. • DRAGON operates 24/7 for multi-week experiments DRAGON Beam suppression; recoil mass only NIM A498(2003)190; A553(2005)491

  8. Late Stellar Burning Reactions Measured at Dragon. 12C(12C,ɣ)24Mg 40Ca(,)44Ti

  9. 12C+12C24Mg While the 12C(12C,ɣ)24Mg reaction is not particular important in carbon burning; however, it shows interesting features that are not observed in the particle exit channels. One is that it has far fewer resonances that are not easily identified with the molecular resonances in the particle channels.

  10. Dragon solid target Target in position Monitor counter

  11. Dragon BGO array Split into two sections.

  12. Spectra 6 MeV ɣ-ray spectra total DSSSD recoil spectrum Double coincidence 6 me 6 MeV cm Esum>18 MeV

  13. Spectra 6 MeV Off resonance, 6.4 MeV ɣ-ɣ-correlations There is clear evidence for strong transitions through intermediate states for the 6.0 and 6.8 MeV resonances.

  14. Spectra 8 MeV 8.0 MeV 7.5 MeV Geant 3 calculations: conclusion the 6 MeV resonances are likely J=2, the 8 MeV resonances J=4.

  15. 1.157 MeV COMPTEL 40Ca(,)44Ti Important for production CGRO Cas A

  16. Observation of 44Ti Ti isotopic anomalies in pre-solar grains Detection of g-rays from 44Ti in space COMPTEL image of Cas A SN1987A Nittler et al., Astrophys. J. 462 (1996) Iyudin et al., Astron. Astrophys. 284 (1994) Schönfelder et al., Proc. 5th Comp. Sym. (2000)

  17. Recent 40Ca + 4He Reaction Study;Experiment: Activation followed by AMS determination H. Nassar et al., Nucl. Phys. A 758 (2005) 411c M. Paul, et al., Nucl. Phys. A718 (2003) 239c Level Scheme and Results literature Measured  ~ 5 x Lit. values

  18. Experimental challenges 1. 40Ca beam from Off-line Ion Source with 2+ charge required for acceptance at RFQ (A/q<30) 2. 40Ar contamination (measured with beam in the ionization chamber) 3. Low suppression of 40Ca beam, only ~107 4. A/q ambiguities 44Ti 11+ ↔ 40Ca10+ charge state distribution after the gas target

  19. Charge State Booster SiN foil after gas target

  20. Beam spot on Target August 05 September 05 November 05

  21. Beam Suppression November 05: buncher on buncher off

  22. Ion chamber

  23. 44Ti identification Ionization chamber DE –E measurement recoil identification isobar separation Time-of-Flight coincidence between prompt g ray and recoil detection

  24. g-g coincidence E = 1130 keV/u 1.1 MeV 9.2 MeV

  25. Excitation function 40Ca(a,g)44Ti 1.0 T9 temperature regime 2.8 T9

  26. Reaction rate of 40Ca(a,g)44Ti previous measurements: Prompt Gamma, Nassar2006 statistical model: NON-SMOKER (web, ADNDT 75 2000), Rauscher emp., BRUSLIB DRAGON reaction rate: measured range Ecm= 2.1 – 4.2 MeV + wg of known resonances from prompt gamma studies Ecm > 4.2 MeV

  27. Implications of reaction rate on 44Ti yield Conclusions: 40% increase of 44Ti yield compared to empirical model by Rauscher et al. 2000 Measured uncertainty of the reaction rate results in a 1suncertainty of 3% in 44Ti yield 44Ti yield and a 44Ti/ 56Ni ratio comparable to the observations in Cas A and SN1987A. [cf. Nassar et al., Phys. Rev. Lett. 96 (2006)] But, some reactions with short-lived nuclides have large uncertainty in their reaction rate, which is a significant part of the uncertainty of the model calculations

  28. Thank You The DRAGON Collaboration, in particular: Chris Ruiz, Christoph Vockenhuber, Dave Hutcheon, Dave Jenkins and many others… most slides were stolen from them. \ 4004 Wesbrook Mall Vancouver, B.C. Canada V6T 2A3 Tel: 604 222-1047 Fax: 604 222-1074 www.triumf.ca

More Related