SUMMARY. Novae phenomenon see (J.Jose talk) Why is 18 F important? State of knowledge of 18 F(p,a) reaction. What can we learn from the THM study

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2 SUMMARY Novae phenomenon see (J.Jose talk) Why is F important? State of knowledge of F(p,a) reaction What can we learn from the THM study

3 Classical Nova The companion star transfers matter onto the white dwarf star hydrogen-rich material from companion can accumulate on surface. The temperature and density of the accumulated layers increase with time until it undergoes runaway fusion. g-ray emission

4 WHY IS F IMPORTANT g-ray emission from e + -e - annihilation Line at energy of E= 511 kev (p,g) e + mostly comes from b decay of F F is produced relatively abundantly F lifetime of 158 min is well matched to the timescale for nova ejects to become (p,a) F e + transparent to g-ray emission GIVES THE FIRST SIGNAL AFTER THE EXPLOSION IT IS IMPORTANT TO STUDY THE REACTIONS PRODUCING AND DESTROYING F F(p,a) 15 O is expected to dominate by a factor 1000 For the star energetic this are peanuts! But not for us (g-ray astronomy)

5 Study of F(p,a) 15 O F is radioactive Astrophysical factor is dominated by several resonances in 19 Ne and by interference effects among levels having the same Jp A. Coc, M. Hernanz, J. José, and J.-P. Thibaud Astron. Astrophys. 357, (2000)

6 Previous measurements TRIUMF ORNL ARGONNE TAMU LLN GANIL SPIRAL MLL RIKEN CRIB Most recent references: D. J. Mountford et al PHYSICAL REVIEW C 85, (R) (2012) Resonances in 19Ne with relevance to the astrophysically important F( p,α)15o reaction. A. S. Adekola et al. PHYSICAL REVIEW C 83, (R) (2011) First proton-transfer study of F + p resonances relevant for novae C. E. Beer et al. PHYSICAL REVIEW C 83, (R) (2011) Direct measurement of the F( p,α)15o reaction at nova temperatures A.M. Laird et al. PRL 110, (2013) Is g-ray Emission from Novae Affected by Interference Effects in the F(p.a)15O Reaction?

7 State of art Direct data down to 250 kev Indirect measurement: info on J p of 19 Ne levels and theoretical calculations F(d,p) 19 Ne A. S. Adekola et al. PRC 83, (R) (2011) 19 F( 3 He t) 19 Ne C. E. Beer et al. PRC 83, (R) (2011) A.M. Laird et al. PRL 110, (2013)

8 New RIKEN by using the Trojan Horse Method FIRST APPLICATION OF THE THM WITH RADIOACTIVE ION BEAM F + d 15 O + a + n d n p 15 O F + p 15 O + a F a For quasi-free mechanism N DIRECT INFO ABOUT THE BARE NUCLEAR X-SEC OF THE 2-BODY REACTION

9 Double-achromatic magnetic separator The experiment: beam O(p,n) F gas target 2 H O MeV/A from AVF cyclotron F beam Scattering 90% purity chamber E= MeV I= pps set-up

10 The experiment: beam tracking and ejecta detection 8 mg/cm m 15 cm 28.7 cm PPAC MCP CD2 2 TARGET m DPSSD array DSSSD Safety disk BEAM TRACKER PARTICLE DETECTORS F + d 15 O + a + n ENERGY AND POSITION MEASURED ENERGY AND POSITION RECONTRUCTED A CAREFULL SIMULATION OF THE SET-UP ALLOWS TO CORRECT THE DATA FOR THE GEOMETRY EFFICIENCY

11 DATA ANALYSIS: Events identification Red : F + d 15 N + a + p q=4.194 MeV Black: F + d 15 O + a + n q=0.658 MeV Blue: F + d F + p + n q=0.213 MeV Green: F + d O + p + p q= MeV q 1 PPAC MCP target q 2 DSSiSD

12 constant DATA ANALYSIS Reaction channel reconstructed by kinematical variables Signature of the predominance of the quasi-free mechanism exp.data Hulten function GOOD AGREEMENT With: Q-value expected position (0.658 MeV) beam profile (exp. Sigma 0.8 MeV) N Q- value for F+d 15 O+a+p

13 DATA ANALYSIS: the bare x-sec THM(=barriers free) CROSS SECTION Integral over the full solid angle by using the Legendre Polinomials s N (E) ASTROPHYSICAL FACTOR Gaussian fit Sigma kev Centrifugal barrier penetrability

14 DATA ANALYSIS THM DATA Hypothesis on J p C. D. NESARAJA et al. PRC 75, (2007) A. S. Adekola, et al., PRC 83 (2011) (R). A. M. Laird et al., PRL. 110, (2013) D.R. Tilley et al. NP A. 595, 1, 1995

15 DATA ANALYSIS: S-FACTOR R-Matrix calculation from DREAM code kev The calculations* have been smeared out at the experimental resolution * C. E. Beer, A. M. Laird et al. PRC 83, (R) (2011)

16 DATA ANALYSIS: S-FACTOR R-matrix calculation from DREAM code 1/2 +, 5/2 +, 3/2 + 1/2+ 5/2+ 3/ kev C. E. Beer, A. M. Laird et al. PRC 83, (R) (2011)

17 CONCLUSION AND PERSPECTIVE THM was successfully applied to radioactive ion beam induced reaction the preliminary results showed the possibility to study the cross section of the F(p,a) 15 O reaction and extract complementary information on S(E) factor To do: Repeating the experiment, with less DISASTERS -- and better RESOLUTION -- Measuring ANGULAR DISTRIBUTION DATA WITH THE «RIGHT (?)» J p assignement New experimental set-up SUPER-ASTRHO Explore the possibility to measure the F(n,a) 15 N reaction (work in progress!)

18 COLLABORATORS - FRANCE A. Coc, F. Hammache, N. de Sereville - JAPAN S. Kubono, H. Yamaguchi, S. Hayakawa, Y. Wakabayashi, T. Komatsubara, N. Iwata, S. Nishimura,T. Teranishini - ITALY S.CHERUBINI, C. Spitaleri, W. Crucillà, M. La Cognata, L. Lamia, R.G. Pizzone, M.L. Sergi, G. Rapisarda, G. Kiss, G.M. M E R C I D O M O A R I G A T O G R A Z I E T H A N K Y O U Photo by roberto amendolia