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Studying the a p-process at ATLAS Catherine M. Deibel

Studying the a p-process at ATLAS Catherine M. Deibel. Joint Institute for Nuclear Astrophysics Michigan State University Physics Division Argonne National Laboratory. Supernovae Type II: ( a ,p ) reactions during the a -rich freeze out

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Studying the a p-process at ATLAS Catherine M. Deibel

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  1. Studying the ap-process at ATLASCatherine M. Deibel Joint Institute for Nuclear Astrophysics Michigan State University Physics Division Argonne National Laboratory

  2. Supernovae Type II: (a,p) reactions during the a-rich freeze out e.g. Radioactive 44Ti destruction and its influence on g-ray surveys Type Ia: due to He accreting CO white dwarfs Classical novae lower mass nucleosynthesis ap-process in Explosive Stellar Environments • X-ray bursts • Breakout of the CNO cycle • Beginning of the rp-process

  3. ap-process in X-Ray Bursts • The early rp-process a series of (p,g), (a,g) and (a,p) reactions • Stalls where (p,g) and (g,p) reactions come into equilibrium and must wait for b+ decay • (a,p) reactions can break out if they are faster than the b+ decay • May be responsible for double-peaked luminosity profiles • Sensitivity studies have shown many of these reactions have significant effects on final abundances and energy output

  4. ap-process in X-Ray Bursts • The early rp-process a series of (p,g), (a,g) and (a,p) reactions • Stalls where (p,g) and (g,p) reactions come into equilibrium and must wait for b+ decay • (a,p) reactions can break out if they are faster than the b+ decay • May be responsible for double-peaked luminosity profiles • Sensitivity studies have shown many of these reactions have significant effects on final abundances and energy output

  5. ap-process in X-Ray Bursts • The early rp-process a series of (p,g), (a,g) and (a,p) reactions • Stalls where (p,g) and (g,p) reactions come into equilibrium and must wait for b+ decay • (a,p) reactions can break out if they are faster than the b+ decay • May be responsible for double-peaked luminosity profiles • Sensitivity studies have shown many of these reactions have significant effects on final abundances and energy output

  6. ap-process in X-Ray Bursts • The early rp-process a series of (p,g), (a,g) and (a,p) reactions • Stalls where (p,g) and (g,p) reactions come into equilibrium and must wait for b+ decay • (a,p) reactions can break out if they are faster than the b+ decay • May be responsible for double-peaked luminosity profiles • Sensitivity studies have shown many of these reactions have significant effects on final abundances and energy output

  7. ap-process in X-Ray Bursts • The early rp-process a series of (p,g), (a,g) and (a,p) reactions • Stalls where (p,g) and (g,p) reactions come into equilibrium and must wait for b+ decay • (a,p) reactions can break out if they are faster than the b+ decay • May be responsible for double-peaked luminosity profiles • Sensitivity studies have shown many of these reactions have significant effects on final abundances and energy output

  8. Radioactive Beams: The In-Flight Method • Stable beam impinges on gas target and produces radioactive nuclei via (p,n), (d,n), (d,p), (p,d), (p,t), and (3He,n) reactions • Intensities of up to 3 x 106 particles/s achieved • Radioactive beams produced: 6He, 7Be, 8Li, 8B, 12B, 10C, 11C, 14O, 15O, 16N, 17F, 20,21Na, 25Al, 33Cl, and 37K (plans to produce heavier radioactive beams in the near future)

  9. (a,p) Studies in Inverse Kinematics with Short-lived Nuclei • Thick (extended) target method: 4He(14O,p)17F [C. Fu et al., Phys. Rev. C 76, 0216603 (2007)] • Thin (localized) 4He target with FMA: 4He(44Ti,47V)p [A.A. Sonzogni et al., Phys. Rev. Lett. 84, 1651 (2000)] • Time-inverse studies (e.g. CH2 target): p(33Cl,30S)4He [C.M. Deibel et al., in preparation (2009)]

  10. Limitations of Previous (a,p) Studies • Lack of radioactive beams or low intensity radioactive beams • Thick target method • Acceptance • Resolution of reaction products • Identification of products from process of interest • Thin (localized) target method • Small acceptance (≤ 2.5°) • Particle identification of light recoils • Time-inverse reactions • Separation of primary and secondary beams • Particle identification in Si detectors • Heavy recoil identification

  11. Prototype Target fan Si array Si array Beam Recoil Detector HELIOSHELIcal Orbit Spectrometer • Consists of a target fan, Si strip detector array (to detect light recoils) and 0° detector (to detect heavier recoils) housed in a 3 T solenoid • Magnetic field allows unique particle identification based on particle’s cyclotron frequency: Tc=2pm/(qB) • Energy resolution in laboratory is equal to that of the center-of-mass system

  12. 11B(d,p)12B 11B(d,p)12B 12B(d,p)13B 12B(d,p)13B “Conventional” HELIOS Preliminary Improved Resolution of HELIOS

  13. Original design Solid targets Detection of backward light recoils Detection of heavy recoils at 0° ap-process studies with HELIOS Prototype Si Array Beam Target fan Recoil detector

  14. ap-process studies with HELIOS • Original design • Solid targets • Detection of backward light recoils • Detection of heavy recoils at 0° • Additions: • Gas target: allows 3,4He targets Prototype Si Array Beam Gas target Recoil detector

  15. HELIOS Gas Target • Gas targets currently used in the SplitPole Spectrograph and CPT areas • LN2 cooled • effective thickness of 80 mg/cm2 • Modified design will allow for use in HELIOS for • direct (a,p) reaction studies • other indirect studies via transfer reactions such as (3He,d), (3He,t), (4He, 3He), (4He,t), etc.

  16. ap-process studies with HELIOS • Original design • Solid targets • Detection of backward light recoils • Detection of heavy recoils at 0° • Additions: • Gas target: allows 3,4He targets Prototype Si Array Beam Gas target Recoil detector

  17. ap-process studies with HELIOS • Original design • Solid targets • Detection of backward light recoils • Detection of heavy recoils at 0° • Additions: • Gas target: allows 3,4He targets • Full Si array allows almost 4p acceptance Si Array Beam Gas target Recoil detector

  18. ap-process studies with HELIOS Ep (MeV) q (deg) 4He(34Ar,p)37K gs 4He(34Ar,p)37K 3 MeV

  19. ap-process studies with HELIOS • Original design • Solid targets • Detection of backward light recoils • Detection of heavy recoils at 0° • Additions: • Gas target: allows 3,4He targets • Full Si array allows almost 4p acceptance Si Array Beam Gas target Recoil detector

  20. ap-process studies with HELIOS • Original design • Solid targets • Detection of backward light recoils • Detection of heavy recoils at 0° • Additions: • Gas target: allows 3,4He targets • Full Si array allows almost 4p acceptance • PPAC and IC allows for more robust particle identification of heavier recoils, beam, and beam contaminants Si Array Beam Gas target PPAC and IC

  21. Conclusions • The (a,p)-process has far ranging effects for XRBs and other sites of explosive nucleosynthesis • The production of new and heavier radioactive beams will enable new (a,p) studies • HELIOS is already a powerful tool for reaction studies in inverse kinematics • With proposed upgrades it will be uniquely suited for direct (a,p) studies by overcoming the limitations of recoil separation, poor resolution, low acceptance, and other problems encountered in previous (a,p) studies

  22. B. B. Back N. Antler S. Baker J. Clark C. M. Deibel B. J. DiGiovine S. J. Freeman N. J. Goodman Z. Grelewicz J. Rohrer J. P. Schiffer J. Snyder M. Syrion J. C. Lighthall A. Vann J. R. Winkelbauer A. H. Wuosmaa Thank you!HELIOS Collaboration S. Heimsath C. Hoffman B. P. Kay H. Y. Lee C. J. Lister S. T. Marley P. Mueller R. C. Pardo K. E. Rehm

  23. Thick target method a(14O,p)17F • Experimental set up and excitation energy spectrum [C. Fu et al., Phys. Rev. C 76, 0216603 (2007)]

  24. 4He(44Ti,47V)p 2.2o 4He(34Ar,37K)p 3.6o 4He(30S,33Cl)p 4.2o 4He(30P,33S)p 4.0o 4He(22Mg,25Al)p 6.1o 4He(18Ne,21Na)p 7.0o 4He(14O,17F)p 8.1o ←FMA acceptance (2.5o) Thin target method: a(44Ti,47V)p • FMA acceptance (table), spectra of FMA focal plane without and with 4He in gas target (upper right), and Si spectrum of beam and contaminants (lower right) [A.A. Sonzogni et al., Phys. Rev. Lett. 84, 1651 (2000)]

  25. Time-inverse method: p(33Cl,30S)a Preliminary Results- a kinematic curve highlighted • Experimental set-up and preliminary a spectrum [C.M. Deibel et al, in preparation (2009)] 33Cl CH2 target a’s DE-E detector Experimental Set-up

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