Jennifer Fallis - ERAWAST Workshop II Using beams of reclaimed 44 Ti to explore the mechanism of core collapse in supernovae Jennifer Fallis TRIUMF

Jennifer Fallis - ERAWAST Workshop II 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: – 44 Ti( TUDA – 44 Ti( ,  DRAGON – 44 Ti(p,  DRAGON (& EMMA?) Other TRIUMF interests

Jennifer Fallis - ERAWAST Workshop II 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. Supernova observables

Jennifer Fallis - ERAWAST Workshop II Ti production In neutrino driven explosions: 44 Ti 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 – 44 Ti yield a sensitive diagnostic of the explosion mechanism –Thus, VERY useful for models to make comparisons against Timmes et al. (1996) And  p-rich freeze out Magkotsios et al. ApJ suppl, 191 (2010)

Jennifer Fallis - ERAWAST Workshop II Most important reactions determined from sensitivity studies Magkotsios et al. (2010):The et al. (1998) 44 Ti( ,p) 47 V 40 Ca( ,  ) 44 Ti 45 V(p,  ) 46 Cr 40 Ca( ,p) 43 Sc 17 F( ,p) 20 Ne 21 Na( ,p) 24 Mg 41 Sc(p,  ) 44 Ti 44 Ti(p,  ) 45 V 57 Ni(p,  ) 58 Cu 43 Sc(p,  ) 44 Ti 44 Ti( ,p) 47 V 45 V(p,  ) 46 Cr 40 Ca( ,  ) 44 Ti 57 Co(p,n) 57 Ni 36 Ar( ,p) 39 K 44 Ti( ,  ) 48 Cr 12 C( ,  ) 16 O 57 Ni(p,  ) 58 Cu 58 Cu(p,  ) 59 Zn 36 Ar( ,  ) 40 Ca 44 Ti(p,  ) 45 V 57 Co(p,  ) 58 Ni 57 Ni(n,  ) 58 Cu 54 Fe( ,n) 57 Ni 40 Ca( ,p) 43 Sc Measured at TRIUMF with DRAGON Letter of intent submitted, but this is a challenging beam to produce

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

Jennifer Fallis - ERAWAST Workshop II Experimental data for 44 Ti( ,p) –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. Only measurements are by Sonzogni et al. [PRL 84 (2000)] :

Jennifer Fallis - ERAWAST Workshop II Experimental data for 44 Ti( ,p) –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 Only measurements are by Sonzogni et al. [PRL 84 (2000)] :

Jennifer Fallis - ERAWAST Workshop II How to measure 44Ti( ,p)47V: 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 44 Ti, available through the ERAWAST program in the TRIUMF off-line ion source difficult to produce and extract

Jennifer Fallis - ERAWAST Workshop II The plan for 44 Ti beams off-line: 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. Supernanogan SUPERNANOGAN

Jennifer Fallis - ERAWAST Workshop II Ti ( ,p) Requirements Previous 44 Ti( ,p) experiment: 10 5 pps A TUDA measurement 1 MeV lower in energy requires ~10 12 total ions on target With ~10 16 atoms available we would require: 0.01% combined source and accelerator efficiency More 44 Ti and better efficiencies would allow for measurements at even lower energies.

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

Jennifer Fallis - ERAWAST Workshop II The plan for 44 Ti beams off-line 44 Ti can be provided in the form of TiF 4 TiF 4 sublimates at 284  C Lessons from recent 33 S 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 TiF 4. … But this needs testing…

Jennifer Fallis - ERAWAST Workshop II Efficiency tests - Done Ti wire sputter test: Wire produced ~ x10 9 pps 48 Ti 7+ at the source cup Ran for 5 days 48 Ti 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% Good enough… but not great

Jennifer Fallis - ERAWAST Workshop II 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 TiF 4 in water.

Jennifer Fallis - ERAWAST Workshop II 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 TiF 4 in water. –An oven for TiF 4 tests has been ordered –TiF 4 needs to be acquired –Hope to run in winter shutdown (late Dec. - early Apr.)

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

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

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

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

Jennifer Fallis - ERAWAST Workshop II The experiments: 44 Ti( ,p) at TUDA # 12 hour shiftsEvents/da y Cross-section (mb) E C.M. (MeV)  With 10 6 pps beams

Jennifer Fallis - ERAWAST Workshop II So, we have a 44 Ti beam what else can we do with it…

Jennifer Fallis - ERAWAST Workshop II Ti production destruction Magkotsios et al. (2010): The et al. (1998) 44 Ti( ,p) 47 V 44 Ti( ,  ) 48 Cr - 44 Ti(p,  ) 45 V Rates usedNON-SMOKERSMOKER Radiative capture

Jennifer Fallis - ERAWAST Workshop II ~20 keV/u

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

Jennifer Fallis - ERAWAST Workshop II

Raw suppression for p-capture Up to with  +H.I. coincidence

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

Jennifer Fallis - ERAWAST Workshop II 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 Ti ( ,  ) Requirements Expected yields for 44 Ti( ,  ): –8.7x at high E limit of Gamow window (6.2 Mev) –1.0x nearing lower limit of Gamow window (3.6 MeV) Yields down to 3x were measured at DRAGON during the 40 Ca( ,  ) 44 Ti measurement. For beams of 10 8 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 33 S(p,  ) run We will be limited by time, which is  -1 beam intensity

Jennifer Fallis - ERAWAST Workshop II for 10 8 pps –6.2 MeV: ~0.6 counts/hr at the end detector. for 10 9 pps –6.2 MeV: ~6 counts/hr –4.9 MeV (middle of Gamow window) : ~0.4 counts/hr For pps –3.6 MeV: ~0.14 counts/hr 44Ti ( ,  ) Requirements

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

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

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

Jennifer Fallis - ERAWAST Workshop II EMMA (ElectroMagnetic Mass Analyser) ? CH 2 target PGAC, IC, Si detector, etc… But not yet assembled or commissioned

Jennifer Fallis - ERAWAST Workshop II Summary of The Plan Test the efficiency of TiF 4 from Supernanogan Acquire safety approval Run 44 Ti( ,p) 47 V at TUDA Guided by TUDA results, confirm or deny the N ON -S MOKER rate for 44 Ti( ,  ) 48 Cr at DRAGON … Meanwhile, spend more time looking into the possibility of measuring 44 Ti(p,  ) 45 V at both DRAGON and EMMA Feasible on a ~1 yr time scale

Jennifer Fallis - ERAWAST Workshop II 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 Collaborators

Jennifer Fallis - ERAWAST Workshop II