33 Sn Cross Section Implications for Neutron Capture

33 S(n, ) Cross Section: Implications for Neutron Capture Therapy and Astrophysics Javier Praena 1, José Manuel Quesada 1, Manuel Lozano 1, Pierfrancesco Mastinu 2, Carlos Guerero 4, Eric Berthoumieux 4, and Ignacio Porras 3 1) Universidad de Sevilla, Spain 2) Laboratori Nazionali di Legnaro, INFN, Italy 3) Universidad de Granada, Spain 4) CERN, Switzerland 1 Javier Praena, CNA-Universidad de Sevilla, España

Plan of the talk 1. 2. 3. 4. 5. 6. Motivations. Sample coatings. nat. S, 33 S. Rutherford Back. Scattering analysis at CNA (PIXE). Micromegas. Some signals before PS Inyector broke down. 2012 compaing: parasitic mode. 2 Javier Praena, CNA-Universidad de Sevilla, España

Motivations • Micromegas for (n, ) reactions at n_TOF, (n, p). • Medical Physics • 33 S as cooperative target for BNCT. • Astrophysics: • Origin of 36 S: although the role of 33 S seems to be solved due to the 34 S as bottle-neck. Schatz et al • Accurate experimental data for testing Hauser-Feshback statistical model used in p-process. Kappeler 3 Javier Praena, CNA-Universidad de Sevilla, España

nat. S and 33 S samples • Bibliographic research. • Person in charged: Wil Vollenberg of Vacum Surface Coatings at CERN. • Sublimation of sulfur in vacuum. 4 Javier Praena, CNA-Universidad de Sevilla, España

nat. S and 33 S samples Evaporation on Kapton and Mylar BAD ADHERENCE 5 Javier Praena, CNA-Universidad de Sevilla, España

nat. S and 33 S samples Previous evaporation of Cu on Kapton (Cr and Ti) taken proffit of the experience with 10 B. Even the quantity of nat. S was high the adherence was poor. And after four days it could be noticed aging effects Simple Method for Making Sulfur Targets D. D. Watson ; Rev. Sci. Instrum. 37, 1605 (1966); Ag 2 S formation by sulfur evaporation at 200 ºC and condensation on bulk Ag heated at 150 ºC. 6 Javier Praena, CNA-Universidad de Sevilla, España

nat. S and 33 S samples FINAL METHOD: external heating of the chamber. Also Kapton (60 C) I=70 A through crysol con S. In case of 33 S it was evaporated 15 mg (75 m/cm 2, thick) and 5 mg (25 m/cm 2, thin) TIME: 1 h vacuum pump, 2 h heating of Kapton and chamber, 5 min 70 A for S 1 h keeping on the temperature after coating. Heated Kapton sample With thin Cu film With thin Cu. S Heating tape 7 Javier Praena, CNA-Universidad de Sevilla, España

RBS analysis at CNA Sample holder Protones de 1782 ke. V Backscattered protons It is possible to calculate the number of atoms per cm 2. We had problems with the Alphatross source of the Tandem, next we will performance with alpha beam. 8 Javier Praena, CNA-Universidad de Sevilla, España

RBS analysis at CNA Proton shoot on zone without Cu. We fixed the at/cm 2 of Cr and Ti. Proton shoot on zone without Cu. We fixed the at/cm 2 of Cu. S. Proton shoot on zone with Cu. We fixed the at/cm 2 of Cu. 9

Samples in Micromegas Mesh-Cu-10 B-Mesh; 6. 1 mm+ 1 mm 6 mm+ 1 mm (B) Mesh-Cu. S-Mesh, 2· 25 g/cm 2 5 mm + 1 mm Mesh-Cu. S-Mesh, 2· 70 g/cm 2 5 mm + 1 mm 2 thick 33 S samples back-to-back. 2 thin 33 S samples back-to-back. 1 10 B 4 C and 1 blank sample. 10 Javier Praena, CNA-Universidad de Sevilla, España

Micromegas in experimental hall Micromegas as parasitic of PPACs 11 Javier Praena, CNA-Universidad de Sevilla, España

Signals during three days We observed signals at: 13. 5 ke. V, 22 ke. V, 56 ke. V, 80 ke. V, 200 e. V? ? ? 12 Javier Praena, CNA-Universidad de Sevilla, España

Bad news and the future The inyector of the PS was broken tha data 16/11/12 and the CERN compaing 2011 was finished. We expected 6 days more. During the three days we were also testing different voltages. • We should perform the experiment next year 2012 (middle, please). • We suppose we should be again parasitic of PPAC. • We would like to perform the experiment with the big Micromegas: • 6 samples of 33 S. • 2 samples of 10 B 4 C back-to-back (to study the effect). • 2 blank samples back-to-back. 13 Javier Praena, CNA-Universidad de Sevilla, España

THANK YOU FOR YOUR ATTENTION 14 Javier Praena, CNA-Universidad de Sevilla, España

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63 Cu(n, ) -> Q=1715 ke. V (69%) 63 Cu(n, p) -> Q=715 ke. V 50 Cr(n, ) -> Q=319 ke. V (2%) 33 S(n, p) -> Q=533 ke. V 17 O(n, ) -> Q=1817 ke. V (0. 03%) 47 Ti(n, p) -> Q=182 ke. V (7%) 47 Ti(n, ) -> Q=2189 ke. V 63 Cu(n, ) -> Q=1715 ke. V Elastic scattering from H 17

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