1 / 25

Trojan Horse method and radioactive ion beams:

Trojan Horse method and radioactive ion beams: study of 18 F( p,a ) 15 O reaction at astrophysical energies. 18 F+p  15 O +  @ CRIB. Marisa Gulino INFN,LNS, Catania, Italy Università di Enna “Kore”, Enna, Italy. Nucleus-Nucleus 2012 San Antonio (TX).

honora
Download Presentation

Trojan Horse method and radioactive ion beams:

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. Trojan Horse method and radioactive ion beams: study of 18F(p,a)15O reaction at astrophysical energies 18F+p15O + @ CRIB Marisa Gulino INFN,LNS, Catania, Italy Università di Enna “Kore”, Enna, Italy Nucleus-Nucleus 2012 San Antonio (TX)

  2. Astrophysical motivations • Gamma-ray emission of energy 511 keV from novae is dominated by the positron annihilation following the b+ decay of unstable nuclei • 18F is especially important because • It is produced relatively abundantly • Its lifetime of ∼158 min is well matched to the timescale for nova ejecta to become transparent to g-ray emission • IT IS IMPORTANT TO STUDY THE REACTIONS PRODUCING AND DESTROYING 18F • as 18F(p,a)15O • The 18F(p,a)15O reaction influence the 15O production considered as a key isotope for the escape from the hot- CNO cycle to the rp-process (p,g) 18F (p,a) AX b+ Nucleus-Nucleus 2012 San Antonio (TX)

  3. Astrophysical motivations • 18F(p,a)15O • Astrophysical factor is dominated by several resonances in19Ne A. Coc, M. Hernanz, J. José, and J.-P. ThibaudAstron. Astrophys. 357, 561–571 (2000) Nucleus-Nucleus 2012 San Antonio (TX)

  4. State of Art LLN TRIUMF GANIL- SPIRAL ARGONNE RIKEN – CRIB ORNL TAMU Mostrecentreferences: D. J. Mountfordet al PHYSICAL REVIEW C 85, 022801(R) (2012) “Resonances in 19Ne with relevance to the astrophysically important 18F( p,α)15O reaction.” A. S. Adekolaet al. PHYSICAL REVIEW C 83, 052801(R) (2011) “First proton-transferstudyof 18F + presonancesrelevantfornovae” C. E. Beeret al. PHYSICAL REVIEW C 83, 042801(R) (2011) “Direct measurement of the 18F( p,α)15O reaction at nova temperatures” Nucleus-Nucleus 2012 San Antonio (TX)

  5. State of Art DIRECT EXPERIMENT C. E. Beer et al. PHYSICAL REVIEW C 83, 042801(R) (2011) DIRECT EXPERIMENT TRANSFER REACTION A. S. Adekola et al. PHYSICAL REVIEW C 83, 052801(R) (2011) D. J. Mountford et al PHYSICAL REVIEW C 85, 022801(R) (2012) Nucleus-Nucleus 2012 San Antonio (TX)

  6. New measurement @ CRIB by using the Trojan Horse Method A (x+s) + B  C + D + S B + x C + D n d S A= Trojan Horse nucleus S x nuclear field x x p x 15O B EBA >EC EC C a 18F EBx= ECD – Q2Body (pcp) EBA= A-B relative energy EC= A-B Coulomb Barrier D 18F + d15O + a + n 18F + p15O + a Nucleus-Nucleus 2012 San Antonio (TX)

  7. TURNING THE IDEA INTO PRACTICE Assuming the QF mechanism is dominant the process can be represented in Feynman diagrams ✚ Three body reaction Virtual decay Virtual reaction Half off-shell (astrophysical process) In PWIA: Deduced Need direct data for normalization Measured at high energy Calculated α

  8. CRIB set-up BEAM PRODUCTION 18O(p,n)18F Double-achromaticmagneticseparator gas target 2H 18O+8 @ 4.5-5 MeV/A from AVF cyclotron Scattering chamber Wienfilter Nucleus-Nucleus 2012 San Antonio (TX)

  9. 18F beam development Test fascio BEAM PURITY > 98% Ebeam = 48.7 MeV s = 0.8 MeV Primary beam: 18O 8+, 4.5-5 MeVA Production target: H2 Production reaction: 18O(p,n)18F Nucleus-Nucleus 2012 San Antonio (TX)

  10. EXPERIMENTAL SETUP(otherthan CRIB.....) 188 mg/cm2 28.7 cm  0.5 m 15 cm   CD2 2 TARGET PPAC MCP 0.107 m DSSSD Safety disk DPSSD array Beam@PPAC 2.4 106 pps 48.7 + 0.8 MeV Front view of DPSSD array ASTRHO: Array of Silicons for TRojanHOrse Nucleus-Nucleus 2012 San Antonio (TX)

  11. BEAM TRACKER x q1 y  q2 target z PPAC MCP DSSiSD DPSSD Beam track reconstruction event by event mm mm mm mm mm mm Nucleus-Nucleus 2012 San Antonio (TX)

  12. Q-VALUE SPECTRUM 18F+d  15N+a+p q = 4.194 MeV 18F+d  18O+p+p q = 0.213 MeV 18F+d  18F+p+n q = -2.225 MeV 1 + 2 + 3 18F+d  15O+a+n q = 0.658 MeV • CUTS: • Eventmultiplicity = 2 • E1 > 20 MeV Nucleus-Nucleus 2012 San Antonio (TX)

  13. EVENT SELECTION Red : 18F + d  15N + a + p Black: 18F + d  15O + a + n Blue: 18F + d  18F + p + n Green: 18F + d  18O + p + p “1”+“2”+“3” Nucleus-Nucleus 2012 San Antonio (TX)

  14. Q-VALUE SPECTRUM • Correlation E13- E12 • Correlation E1 - q1 • CUTS: • Eventmultiplicity = 2 • E1 > 20 MeV • GOOD AGREEMENT with • q-value expected position (0.658 MeV) • and beam profile (exp. Sigma 0.8 MeV) Nucleus-Nucleus 2012 San Antonio (TX)

  15. HINTS FOR QF MECHANISM If the quasi-freemechanismispredominant Minumumof ps N Hultenfunction Nucleus-Nucleus 2012 San Antonio (TX)

  16. BARE NUCLEUS CROSS SECTION First TH exp. with RIB 38 keV PRELIMINARY BARENUCLEUS NUCLEARCROSSSECTION Nucleus-Nucleus 2012 San Antonio (TX)

  17. Conclusions and Perspective • THM was successfully applied to radioactive ion beam induced reaction • the beam is tracked event by event and the kinematical variables were consequently reconstructed • the preliminary results showed the possibility to study the cross section of the 18F(p,a)15O reaction and extract complementary information on S(E) factor  (work in progress) • To do:Increase statistics and confirm the results with a second experimental run • Explore the possibility to measure the 18F(n,a)15N reaction Nucleus-Nucleus 2012 San Antonio (TX)

  18. THANK YOU FOR YOUR ATTENTION ! THANK YOU TO ALL THE COLLABORATION ! S. Cherubini, M. Gulino, M. La Cognata, L. Lamia, G. G. Rapisarda, C. Spitaleri, S. Kubono, H. Yamaguchi, S. Hayakawa, Y. Wakabayashi,‡, N. Iwasa§, S. Kato ¶, H. Komatsubara k, T. Teranishi ††, Coc‡‡, N. De Séréville§§ and F. Hammache§§ Dipartimento di Fisica ed Astronomia, Università di Catania and INFN-LNS, Catania, Italy †INFN-LNS, Catania, Italy and UniKORE, Enna, Italy Center for Nuclear Study, The University of Tokyo, Japan ‡Present address KEK, Japan §Department of Physics, Tohoku University, Sendai, Japan ¶Department of Physics, Yamagata University, Yamagata, Japan kDepartment of Physics, Tsukuba University, Tsukuba, Japan ††Department of Physics, Kyushu University, Fukuoka, Japan ‡‡Centre de Spectrométrie Nucléaire et de Spectrométrie de Masse, IN2P3, F-91405 Orsay, France §§Institut de Physique Nucléaire, IN2P3, F-91405 Orsay, France Nucleus-Nucleus 2012 San Antonio (TX)

  19. BARE NUCLEUS CROSS SECTION Nucleus-Nucleus 2012 San Antonio (TX)

  20. TrojanHorseforResonanceReactions ON-SHELL HALF OFF-SHELL PENETRABILITY Indipendentfromspectroscopicfactorvalue

  21. BEAM position on PPAC and MCP DREB 2012 - Direct Reactions with Exotic Beams

  22. CUTS DREB 2012 - Direct Reactions with Exotic Beams

  23. State of Art Manyexperimentsperformedusing 18F beam @ ARGONNE - ATLAS LLN ORNL TRIUMF GANIL- SPIRAL RIKEN – CRIB TAMU Directmeasurements thick target method Indirect measurement  (d,p) (d,n) stripping reaction Mostrecentreferences: D. J. Mountfordet al PHYSICAL REVIEW C 85, 022801(R) (2012) “Resonances in 19Ne with relevance to the astrophysically important 18F( p,α)15O reaction.” A. S. Adekolaet al. PHYSICAL REVIEW C 83, 052801(R) (2011) “First proton-transferstudyof 18F + presonancesrelevantfornovae” C. E. Beeret al. PHYSICAL REVIEW C 83, 042801(R) (2011) “Direct measurement of the 18F( p,α)15O reaction at nova temperatures” Nucleus-Nucleus 2012 San Antonio (TX)

  24. Summary • Astrophysical motivations & State of Art • Indirect measurement by Trojan Horse Method • Experimental set-up  new apparatus for RIB application • Data Analysis and preliminary results Nucleus-Nucleus 2012 San Antonio (TX)

  25. “Plus” of the TH methods Typical QF process cross sections (mbarn/sr) though measuring astrophysical ones The TH cross sections is the purely NUCLEAR one: no Coulomb barrier effects No electron screening effects: an INDEPENDENT piece of information can be obtained on the electron screening potential Ue by comparison to direct data Can be extended to use QFR for studying NEUTRON induced reactions (VNM Virtual Neutron Method) “Minus” of the TH methods 1) Competition between QF and other reaction mechanisms: identification of the convenient kinematical conditions may need more than one experiment run 2) Some dependence on theoretical models 3) Need of direct data at higher energies for normalization S. Cherubini et al., ApJ 457 (1996) 855

More Related