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Using beams of reclaimed 44 Ti to explore the mechanism of core collapse in supernovae

Using beams of reclaimed 44 Ti to explore the mechanism of core collapse in supernovae. Jennifer Fallis TRIUMF. Road map. 44 Ti production in supernovae & importance of 44 Ti( ,p) 47 V Creating beams of 44 Ti at TRIUMF Planned and other possible measurements:

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Using beams of reclaimed 44 Ti to explore the mechanism of core collapse in supernovae

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  1. Using beams of reclaimed 44Ti to explore the mechanism of core collapse insupernovae Jennifer Fallis TRIUMF Jennifer Fallis - ERAWAST Workshop II - 2011

  2. Road map • 44Ti production in supernovae & importance of 44Ti(,p)47V • Creating beams of 44Ti at TRIUMF • Planned and other possible measurements: • 44Ti(,p) @ TUDA • 44Ti(,) @ DRAGON • 44Ti(p,) @ DRAGON(& EMMA?) • Other TRIUMF interests Jennifer Fallis - ERAWAST Workshop II - 2011

  3. Supernova observables • Supernovae explosions are incredibly complex and most observables are very general, resulting from the overall features of the explosion. • Light curves - include all energy given off as photons. • Spectroscopy provides elemental abundances, but only measures the total number of all isotopes of any given element. • Observations of individual isotopes are particularly useful for comparing models to observations • presolar grains • -ray telescope observations • Accurate models, however, need precise reaction rates to be sufficiently constrained. Jennifer Fallis - ERAWAST Workshop II - 2011

  4. 44Ti production And p-rich freeze out Magkotsios et al. ApJ suppl, 191 (2010) Timmes et al. (1996) In neutrino driven explosions: 44Ti is synthesized in the -rich freeze out that occurs in the shock-heated Si layer that lies just above the detonating core and so the amount ejected sensitively depends on location of the ‘mass cut’ • Material that ‘falls back’ is not available for detection • 44Ti yield a sensitive diagnostic of the explosion mechanism • Thus, VERY useful for models to make comparisons against Jennifer Fallis - ERAWAST Workshop II - 2011

  5. Most important reactions determined from sensitivity studies Measured at TRIUMF with DRAGON Letter of intent submitted, but this is a challenging beam to produce Jennifer Fallis - ERAWAST Workshop II - 2011

  6. Experimental data for 44Ti(a,p) Upper limit of Gamow window at 3 GK Only measurements are by Sonzogni et al. [PRL 84 (2000)] : • 4 data points • Energies higher than those required to study the reaction at astrophysically relevant temperatures Jennifer Fallis - ERAWAST Workshop II - 2011

  7. Experimental data for 44Ti(a,p) Only measurements are by Sonzogni et al. [PRL 84 (2000)] : • 4 data points • Energies higher than those required to study the reaction at astrophysically relevant temperatures • Found a rate 2x higher than the SMOKER rates. Jennifer Fallis - ERAWAST Workshop II - 2011

  8. Experimental data for 44Ti(a,p) Only measurements are by Sonzogni et al. [PRL 84 (2000)] : • 4 data points • Energies higher than those required to study the reaction at astrophysically relevant temperatures • Found a rate 2x higher than the SMOKER rates. • Hoffman et al., [ApJ 715 (2010)] recalculated a rate from this data & find a rate consistent with NON-SMOKER within uncertainties Jennifer Fallis - ERAWAST Workshop II - 2011

  9. How to measure 44Ti(,p)47V: difficult to produce and extract • 44Ti targets? Daniel Bemmerer’s talk this morning • 44Ti beams? • On-line production using the ISOL technique followed by immediate acceleration • Off-line production using an enriched source of 44Ti, available through the ERAWAST program in the TRIUMF off-line ion source Jennifer Fallis - ERAWAST Workshop II - 2011

  10. The plan for 44Ti beams off-line: SUPERNANOGAN Supernanogan • ISAC-I accelerator limited to A/q =6. • Use of a stipping foil can provide beams of ions up to A=30 • For beams above A=30 high charge states are needed from the source. • Supernanogan ECR source can provide these high charge states • Beam up to A=150 from the off-line source can now be accelerated. Jennifer Fallis - ERAWAST Workshop II - 2011

  11. 44Ti (,p) Requirements • Previous 44Ti(,p) experiment: 105 pps • A TUDA measurement 1 MeV lower in energy requires ~1012 total ions on target • With ~1016 atoms available we would require: • 0.01% combined source and accelerator efficiency • More 44Ti and better efficiencies would allow for measurements at even lower energies. Jennifer Fallis - ERAWAST Workshop II - 2011

  12. The plan for 44Ti beams off-line: SUPERNANOGAN Supernanogan Source efficiencies depend on the method of acquiring material: • Gas leak • Sputter source • Oven 1 - 10% efficiency 0.01 - 0.1% efficiency • … depends on chemical • properties of material • 0.1% - 1% ? Jennifer Fallis - ERAWAST Workshop II - 2011

  13. The plan for 44Ti beams off-line • 44Ti can be provided in the form of TiF4 • TiF4 sublimates at 284C • Lessons from recent 33S beam: • Melting point 115C / Boiling point 445C • Didn’t even have to turn on oven to get a good vapour pressure! • There is a good chance of getting up to 1% efficiency out of source when using TiF4. … But this needs testing… Jennifer Fallis - ERAWAST Workshop II - 2011

  14. Efficiency tests - Done Good enough… but not great Ti wire sputter test: • Wire produced ~2.7- 3.6x109 pps 48Ti7+ at the source cup • Ran for 5 days • 48Ti is 73.72% of natural abundance • No measured difference in Ti wire weight after the test (0.1mg scale) Minimum sputter efficiency was 0.017% Jennifer Fallis - ERAWAST Workshop II - 2011

  15. Efficiency tests - planned • The Problems: • putting a small enough sample in the Supernanogan to use it up in the time available for beam development • Knowing how much material was in the sample • The Solution: using a small amount of a low concentration solution of TiF4 in water. Jennifer Fallis - ERAWAST Workshop II - 2011

  16. Efficiency tests - planned • The Problems: • putting a small enough sample in the Supernanogan to use it up in the time available for beam development • Knowing how much material was in the sample • The Solution: using a small amount of a low concentration solution of TiF4 in water. • An oven for TiF4 tests has been ordered • TiF4 needs to be acquired • Hope to run in winter shutdown (late Dec. - early Apr.) Jennifer Fallis - ERAWAST Workshop II - 2011

  17. 44Ti is radioactive, t1/2 = 60 y • No other long lived radioactive isotope ever used in OLIS + 14C experiment also has “stage 1” approval (joining forces) + 44Ti beam was produced from an ECR source at Argonne National Lab. SAFETY Jennifer Fallis - ERAWAST Workshop II - 2011

  18. TRIUMF - ISAC I and II ISAC II: up to 16 MeV/u ISAC I: 150 keV/u - 1.9 MeV/u TUDA 2 Jennifer Fallis - ERAWAST Workshop II - 2011

  19. The experiments: 44Ti(,p) at TUDA Jennifer Fallis - ERAWAST Workshop II - 2011

  20. The experiments: 44Ti(,p) at TUDA ∆E E ~200 keV p 44Ti beam Up to 200 Torr of He 47V and 44Ti stopped in exit window Jennifer Fallis - ERAWAST Workshop II - 2011

  21. The experiments: 44Ti(,p) at TUDA EC.M.(MeV) Cross-section (mb) Events/day # 12 hour shifts 5 4 195 2 4 1 65 4 3 0.5 14 10  With 106 pps beams Jennifer Fallis - ERAWAST Workshop II - 2011

  22. So, we have a 44Ti beamwhat else can we do with it… Jennifer Fallis - ERAWAST Workshop II - 2011

  23. 44Ti production destruction Radiative capture Jennifer Fallis - ERAWAST Workshop II - 2011

  24. ~20 keV/u Jennifer Fallis - ERAWAST Workshop II - 2011

  25. Charge state booster (SNi foil, 100nm thick) Jennifer Fallis - ERAWAST Workshop II - 2011

  26. Jennifer Fallis - ERAWAST Workshop II - 2011

  27. Raw suppression for p-capture 108 - 1010 Up to 1015 with +H.I. coincidence Jennifer Fallis - ERAWAST Workshop II - 2011

  28. Current experimental data for 44Ti(a,) (Yes, that’s really all there is…) Jennifer Fallis - ERAWAST Workshop II - 2011

  29. Changes between SMOKER and NON-SMOKER codes:result of suppression of (,) reactions on self conjugate nuclei due to isospin selection rules Jennifer Fallis - ERAWAST Workshop II - 2011

  30. 44Ti (,g) Requirements • Expected yields for 44Ti(,): • 8.7x10-12 at high E limit of Gamow window (6.2 Mev) • 1.0x10-14 nearing lower limit of Gamow window (3.6 MeV) • Yields down to 3x10-16 were measured at DRAGON during the 40Ca(,)44Ti measurement. • For beams of 108 pps, at 6.2 Mev, we expect ~0.6 counts/hr at the end detector. • Count rates of 0.5 counts/hr were measured in the 33S(p,) run • We will be limited by time, which is -1 beam intensity Jennifer Fallis - ERAWAST Workshop II - 2011

  31. 44Ti (,g) Requirements • for 108 pps • 6.2 MeV: ~0.6 counts/hr at the end detector. • for 109 pps • 6.2 MeV: ~6 counts/hr • 4.9 MeV (middle of Gamow window) : ~0.4 counts/hr • For 1010 pps • 3.6 MeV: ~0.14 counts/hr Jennifer Fallis - ERAWAST Workshop II - 2011

  32. Current experimental data for 44Ti(p,) (… I’m sensing a trend …) Jennifer Fallis - ERAWAST Workshop II - 2011

  33. NON-SMOKER cross sections for 44Ti(p,) Jennifer Fallis - ERAWAST Workshop II - 2011

  34. ISAC-I beam energies: 150 keV/u - 1.9 MeV/u This is close to the limit of Ebeam to DRAGON, to measure radiative capture rates for higher temperaturs (up to 4.5 GK) … 44Ti(,): (for upper limit of Gamow window at 3 GK) Eres = 6.2 MeV Ebeam = 1.69 MeV/u 44Ti(p,): (for upper limit of Gamow window at 3 GK) Eres = 3.4 MeV Ebeam = 1.76 MeV/u Jennifer Fallis - ERAWAST Workshop II - 2011

  35. EMMA (ElectroMagnetic Mass Analyser)? CH2 target PGAC, IC, Si detector, etc… But not yet assembled or commissioned Jennifer Fallis - ERAWAST Workshop II - 2011

  36. Summary of The Plan Feasible on a ~1 yr time scale • Test the efficiency of TiF4 from Supernanogan • Acquire safety approval • Run 44Ti(,p)47V at TUDA • Guided by TUDA results, confirm or deny the NON-SMOKER rate for 44Ti(,)48Cr at DRAGON • … Meanwhile, spend more time looking into the possibility of measuring 44Ti(p,)45V at both DRAGON and EMMA Jennifer Fallis - ERAWAST Workshop II - 2011

  37. Collaborators TRIUMF: J. Fallis, C. Ruiz, D. Hutcheon U. Edinburgh: A. St.J. Murphy, G. Lotay, P. J. Woods, M. Aliotta, T. Davinson, D. Mountford, G. Lotay, A. Shotter U. York: B. R. Fulton, A. M. Laird, M. Taggart, S. Fox, C. A. Diget, M. Bently, J. Brown, P. Adsley SFU: J. M. D’Auria UNBC: A. Hussein CSM: U. Greife, U. Hager McMaster: A. A. Chen, J. Chen, D. Irvine, K. Setoodehnia TU-Munich: S. Bishop, A. Parikh, C. Vockenhuber ANL: J. Clark, C. Deibel Jennifer Fallis - ERAWAST Workshop II - 2011

  38. Jennifer Fallis - ERAWAST Workshop II - 2011

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