Virtual Neutron Method applied to the study of 17 O(n,  ) 14 C reaction Marisa Gulino LNS - INFN, Catania & Università di Enna “Kore”

 Why studying 17 O(n,  ) 14 C reaction  From Trojan Horse Method to Virtual Neutron Method  The experiments  data analysis and results  Why studying 17 O(n,  ) 14 C reaction  From Trojan Horse Method to Virtual Neutron Method  The experiments  data analysis and results INPC 2013 Firenze, Italy 2-7 JUNE 2013 SUMMARY

INPC 2013 Firenze, Italy 2-7 JUNE 2013 THE 17 O(n,  ) REACTION: status of art NUCLEAR REACTORS the neutron induced reaction on 14 N and 17 O are the dominant sources of the radioactive isotope 14 C (T 1/2 = 5730 yr). NUCLEAR ASTROPHYSICS In the inhomogeneous big-bang model the 14 C may act as a bottleneck in the production of elements heavier than A=17 anomalies in 18 O/ 16 O and 17 O/ 16 O ratios found in asymptotic giant branch stars and in circumstellar Al 2 O 3 meteorite grains neutron poison in the nucleosynthesis of the s-process elements O+n ± ± ± ± O The cross section of this reaction is characterized by the presence of several narrow resonant states in the 18 O compound nucleus.

INPC 2013 Firenze, Italy 2-7 JUNE 2013 THE 17 O(n,  ) REACTION: status of art Data from: P. E. Koehler and S. M. Graff, Phys. Rev. C 44, 2788 (1991). H. Schatz, F. Kaeppeler, P. E. Koehler, M. Wiescher, and H. P. Trautvetter, Astrophys. J. 413, 750 (1993). R. M. Sanders, Phys. Rev. 104, 1434 (1956) from J. WAGEMANS et al. PHYSICAL REVIEW C (2002) INFLUENCE OF SUBTRESHOLD RESONANCE “ The reaction rate at the astrophysical relevant temperatures was calculated and found to be a factor of 2–2.5 lower than previously adopted.“ DIFFERENCES IN EXPERIMENTAL DATA “The significant impact of the presence of the negative-energy p-wave resonance on the reaction rate was shown.”

INPC 2013 Firenze, Italy 2-7 JUNE 2013 INDIRECT METHODS: Trojan Horse Method reminder IDEA (C. Spitaleri, 1990): Extract the cross section  2Body for A + x  B + b from Quasi-free reaction channel data of a three body reaction T + A  B + b + s where T shows a strong clusterization in x+s A T s x B b E TA = T-A relative energy E C =T-A Coulomb barrier E Ax = E Bb – Q 2body (pcp)

INPC 2013 Firenze, Italy 2-7 JUNE 2013 From TROJAN HORSE to VIRTUAL NEUTRON METHOD A d p n B b spectator participant Detected particles If the Quasi-free mechanism is selected in PWIA the cross section of the reaction n+A  B+b can be deduced N

INPC 2013 Firenze, Italy 2-7 JUNE 2013 FIRST APPLICATION: THE 6 Li(n,  ) REACTION 6 Li d p n 3H3H  spectator participant Detected particles 6 Li(n,  ) 3 H d( 6 Li,  3 H)p J. of Phys. G, Nucl. Part.Phys. 37, (2010) 6 Li(n,  )t cross section ___direct data OTH data

INPC 2013 Firenze, Italy 2-7 JUNE 2013 THE 17 O(n,  ) REACTION: the 17 O+d experiments 14 N+  +n 17 O+d 14 C+  +p 17 O+p  14 N+  17 O+n  14 C+  Two experiments have been - Catania, – Notre Dame, IN, USA EXPERIMENTAL SET-UP MeV CD 2 IC PSD 5° 30°

INPC 2013 Firenze, Italy 2-7 JUNE 2013 THE 17 O(n,  ) REACTION: Identification of reaction channel ONCONC  Carbon selection by  E-E spectra  Coincidence between kinematical calculations and experimental data Q- value of the 17 O+d  14 C+  +p reaction  P

INPC 2013 Firenze, Italy 2-7 JUNE 2013 THE 17 O(n,  ) REACTION: Evidences of QF mechanism A more sensitive check of the predominance of the QF reaction mechanism is achieved by investigating the shape of the experimental momentum distribution of the n and p inside deuteron. DWBA

INPC 2013 Firenze, Italy 2-7 JUNE 2013 THE 17 O(n,  ) REACTION: cross section 11 LNS Experiment ND Experiment PHYSICAL REVIEW C 87, (R) (2013) I) subtreshold level II) resonance populated in l=3 missing in the direct data III) corresponding to the direct data IV) corresponding to the direct data I II III IV III IV

INPC 2013 Firenze, Italy 2-7 JUNE 2013 THE 17 O(n,  ) REACTION: angular distribution 12 PHYSICAL REVIEW C 87, (R) (2013) cos  cm l i =1 l i =0, l i =2 l i =3 l i =1 I II III IV I II l i =1l i =3 III IV l i =2l i =1 l i =0 angular distributions have been measured for the first time

INPC 2013 Firenze, Italy 2-7 JUNE 2013 THE 17 O(n,  ) REACTION: Comparison with direct data N N Data correction for the penetrability of the centrifugal barrier PHYSICAL REVIEW C 87, (R) (2013)

INPC 2013 Firenze, Italy 2-7 JUNE 2013 CONCLUSIONS

M Gulino 1,2, C. Spitaleri 1,3, X.D. Tang 4, G.L. Guardo 1,3, L. Lamia 3, S. Cherubini 1,3, B. Bucher 4, V. Burjan 5, M. Couder 4, P. Davies 4, R. deBoer 4, X. Fang 4, V.Z. Goldberg 6, Z. Hons 5, V. Kroha 5, L. Lamm 4,†, M. La Cognata 1, C. Li 7, C. Ma 4, J. Mrazek 5, A.M. Mukhamedzhanov 6, M. Notani 4, S. OBrien 4, R.G. Pizzone 1, G.G. Rapisarda 1,3, D. Roberson 4, M.L. Sergi 1, W. Tan 4, I.J. Thompson 8, M. Wiescher 4 1 INFN Laboratori Nazionali del Sud, Catania, Italy 2 Università degli Studi di Enna “KORE”, Enna, Italy 3 Dipartimento di Fisica ed Astronomia, Università degli Studi di Catania, Catania, Italy 4 Department of Physics and Joint Institute for Nuclear Astrophysics, University of Notre Dame, IN, USA 5 Nuclear Physics Institute of ASCR, Rez, Czech Republic 6 Cyclotron Institute,Texas A&M University,College Station, TX, USA 7 China Institute of Atomic Energy, Beijing, China 8 Lawrence Livermore National Laboratory, Livermore, CA, USA Contact M Gulino 1,2, C. Spitaleri 1,3, X.D. Tang 4, G.L. Guardo 1,3, L. Lamia 3, S. Cherubini 1,3, B. Bucher 4, V. Burjan 5, M. Couder 4, P. Davies 4, R. deBoer 4, X. Fang 4, V.Z. Goldberg 6, Z. Hons 5, V. Kroha 5, L. Lamm 4,†, M. La Cognata 1, C. Li 7, C. Ma 4, J. Mrazek 5, A.M. Mukhamedzhanov 6, M. Notani 4, S. OBrien 4, R.G. Pizzone 1, G.G. Rapisarda 1,3, D. Roberson 4, M.L. Sergi 1, W. Tan 4, I.J. Thompson 8, M. Wiescher 4 1 INFN Laboratori Nazionali del Sud, Catania, Italy 2 Università degli Studi di Enna “KORE”, Enna, Italy 3 Dipartimento di Fisica ed Astronomia, Università degli Studi di Catania, Catania, Italy 4 Department of Physics and Joint Institute for Nuclear Astrophysics, University of Notre Dame, IN, USA 5 Nuclear Physics Institute of ASCR, Rez, Czech Republic 6 Cyclotron Institute,Texas A&M University,College Station, TX, USA 7 China Institute of Atomic Energy, Beijing, China 8 Lawrence Livermore National Laboratory, Livermore, CA, USA Contact INPC 2013 Firenze, Italy 2-7 JUNE 2013 Thanks to the COLLABORATION