1. Studying the  p-process at ATLAS Catherine M. Deibel Joint Institute for Nuclear Astrophysics Michigan State University Physics Division Argonne National Laboratory

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

3. 3  p-process in X-Ray Bursts The early rp-process a series of (p,  ), (  ) and ( ,p) reactions Stalls where (p,  ) and ( ,p) reactions come into equilibrium and must wait for  + decay ( ,p) reactions can break out if they are faster than the  + 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. 4  p-process in X-Ray Bursts The early rp-process a series of (p,  ), (  ) and ( ,p) reactions Stalls where (p,  ) and ( ,p) reactions come into equilibrium and must wait for  + decay ( ,p) reactions can break out if they are faster than the  + 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. 5  p-process in X-Ray Bursts The early rp-process a series of (p,  ), (  ) and ( ,p) reactions Stalls where (p,  ) and ( ,p) reactions come into equilibrium and must wait for  + decay ( ,p) reactions can break out if they are faster than the  + 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. 6  p-process in X-Ray Bursts The early rp-process a series of (p,  ), (  ) and ( ,p) reactions Stalls where (p,  ) and ( ,p) reactions come into equilibrium and must wait for  + decay ( ,p) reactions can break out if they are faster than the  + 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. 7  p-process in X-Ray Bursts The early rp-process a series of (p,  ), (  ) and ( ,p) reactions Stalls where (p,  ) and ( ,p) reactions come into equilibrium and must wait for  + decay ( ,p) reactions can break out if they are faster than the  + 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. 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 ( 3 He,n) reactions Intensities of up to 3 x 10 6 particles/s achieved Radioactive beams produced: 6 He, 7 Be, 8 Li, 8 B, 12 B, 10 C, 11 C, 14 O, 15 O, 16 N, 17 F, 20,21 Na, 25 Al, 33 Cl, and 37 K (plans to produce heavier radioactive beams in the near future)

9. 9 ( ,p) Studies in Inverse Kinematics with Short-lived Nuclei Thick (extended) target method: 4 He( 14 O,p) 17 F [C. Fu et al., Phys. Rev. C 76, 0216603 (2007)] Thin (localized) 4 He target with FMA: 4 He( 44 Ti, 47 V)p [A.A. Sonzogni et al., Phys. Rev. Lett. 84, 1651 (2000)] Time-inverse studies (e.g. CH 2 target):p( 33 Cl, 30 S) 4 He [C.M. Deibel et al., in preparation (2009)]

10. 10 Limitations of Previous ( ,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. 11

12. 12 Prototype Si array Recoil Detector Target fan Beam HELIOS HELIcal 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: T c =2  m/(qB) Energy resolution in laboratory is equal to that of the center-of-mass system

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

14. 14  p-process studies with HELIOS Target fan Recoil detector Prototype Si Array Beam Original design –Solid targets –Detection of backward light recoils –Detection of heavy recoils at 0°

15. 15  p-process studies with HELIOS Prototype Si Array Gas target Recoil detector Original design –Solid targets –Detection of backward light recoils –Detection of heavy recoils at 0 ° Additions: –Gas target: allows 3,4 He targets Beam

16. 16 HELIOS Gas Target Gas targets currently used in the SplitPole Spectrograph and CPT areas –LN 2 cooled –effective thickness of 80  g/cm 2 Modified design will allow for use in HELIOS for –direct ( ,p) reaction studies –other indirect studies via transfer reactions such as ( 3 He,d), ( 3 He,t), ( 4 He, 3 He), ( 4 He,t), etc.

17. 17  p-process studies with HELIOS Prototype Si Array Gas target Recoil detector Original design –Solid targets –Detection of backward light recoils –Detection of heavy recoils at 0 ° Additions: –Gas target: allows 3,4 He targets Beam

18. 18  p-process studies with HELIOS Si Array Gas target Recoil detector Original design –Solid targets –Detection of backward light recoils –Detection of heavy recoils at 0 ° Additions: –Gas target: allows 3,4 He targets –Full Si array allows almost 4  acceptance Beam

19. 19 4 He( 34 Ar,p) 37 K gs 4 He( 34 Ar,p) 37 K 3 MeV  p-process studies with HELIOS Particlep 3 Hed, 4 Het TOF(ns)21.932.843.765.6  (deg) E p (MeV)

20. 20  p-process studies with HELIOS Si Array Gas target Recoil detector Original design –Solid targets –Detection of backward light recoils –Detection of heavy recoils at 0 ° Additions: –Gas target: allows 3,4 He targets –Full Si array allows almost 4  acceptance Beam

21. 21  p-process studies with HELIOS Si Array Gas target PPAC and IC Original design –Solid targets –Detection of backward light recoils –Detection of heavy recoils at 0 ° Additions: –Gas target: allows 3,4 He targets –Full Si array allows almost 4  acceptance –PPAC and IC allows for more robust particle identification of heavier recoils, beam, and beam contaminants Beam

22. 22 Conclusions The ( ,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 ( ,p) studies HELIOS is already a powerful tool for reaction studies in inverse kinematics With proposed upgrades it will be uniquely suited for direct ( ,p) studies by overcoming the limitations of recoil separation, poor resolution, low acceptance, and other problems encountered in previous ( ,p) studies

23. 23 Thank you! HELIOS Collaboration 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 S. Heimsath C. Hoffman B. P. Kay H. Y. Lee C. J. Lister S. T. Marley P. Mueller R. C. Pardo K. E. Rehm

24. 24 Thick target method  ( 14 O,p) 17 F Experimental set up and excitation energy spectrum [C. Fu et al., Phys. Rev. C 76, 0216603 (2007)]

25. 25 Thin target method:  ( 44 Ti, 47 V)p FMA acceptance (table), spectra of FMA focal plane without and with 4 He 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)] 4 He( 44 Ti, 47 V)p2.2 o 4 He( 34 Ar, 37 K)p3.6 o 4 He( 30 S, 33 Cl)p4.2 o 4 He( 30 P, 33 S)p4.0 o 4 He( 22 Mg, 25 Al)p6.1 o 4 He( 18 Ne, 21 Na)p7.0 o 4 He( 14 O, 17 F)p8.1 o ←FMA acceptance (2.5 o )

26. 26 Time-inverse method: p( 33 Cl, 30 S)  Experimental set-up and preliminary  spectrum [C.M. Deibel et al, in preparation (2009)] Experimental Set-up  ’s CH 2 target  E-E detector 33 Cl Preliminary Results-  kinematic curve highlighted