11 33 S(n, ) Cross Section: Implications for Neutron Capture Therapy and Astrophysics Javier Praena...

11

33S(n,) Cross Section:Implications for Neutron Capture Therapy and Astrophysics

Javier Praena1, José Manuel Quesada1, Manuel Lozano1, Pierfrancesco Mastinu2, Carlos Guerero4, Eric Berthoumieux4,

and Ignacio Porras3

1) Universidad de Sevilla, Spain2) Laboratori Nazionali di Legnaro, INFN, Italy

3) Universidad de Granada, Spain4) CERN, Switzerland

Javier Praena, CNA-Universidad de Sevilla, España

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Plan of the talk

1. Motivations.

2. Sample coatings. natS, 33S.

3. Rutherford BackScattering analysis at CNA (PIXE).

4. Micromegas.

5. Some signals before PS Inyector broke down.

6. 2012 compaing: parasitic mode.


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Motivations


• Micromegas for (n,) reactions at n_TOF, (n,p).

• Medical Physics

• 33S as cooperative target for BNCT.

• Astrophysics:

• Origin of 36S: although the role of 33S 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

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• Bibliographic research.• Person in charged: Wil Vollenberg of Vacum Surface Coatings at CERN.• Sublimation of sulfur in vacuum.

natS and 33S samples


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Evaporation on Kapton and Mylar

BAD ADHERENCE


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Previous evaporation of Cu on Kapton (Cr and Ti) taken proffit of the experience with 10B.

Even the quantity of natS was high the adherence was poor.

And after four days it could be noticed aging effects

Simple Method for Making Sulfur TargetsD. D. Watson ; Rev. Sci. Instrum. 37, 1605 (1966);Ag2S formation by sulfur evaporation at 200 ºC and condensation on bulk Ag heated at 150 ºC.



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FINAL METHOD: external heating of the chamber. Also Kapton (60 C)

I=70 A through crysol con S.

In case of 33S it was evaporated 15 mg (75 m/cm2, thick) and 5 mg (25 m/cm2, 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.

Heating tape

Heated Kapton sampleWith thin Cu film

With thin CuSHeating tape



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RBS analysis at CNA

Protones de 1782 keV Backscattered protons

It is possible to calculate the number of atoms per cm2.

We had problems with the Alphatross source of the Tandem, next we will performance with alpha beam.

Sample holder


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Proton shoot on zone without Cu.We fixed the at/cm2 of Cr and Ti.

RBS analysis at CNA

Proton shoot on zone with Cu.We fixed the at/cm2 of Cu.

Proton shoot on zone without Cu.We fixed the at/cm2 of CuS.

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Mesh-Cu-10B-Mesh; 6.1 mm+ 1mm6 mm+ 1mm (B)

Mesh-CuS-CuS-Mesh, 2·25 g/cm2

5mm + 1mm

Mesh-CuS-CuS-Mesh, 2·70 g/cm2

5mm + 1mm

2 thick 33S samples back-to-back.

2 thin 33S samples back-to-back.

1 10B4C and 1 blank sample.

Samples in Micromegas


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Micromegas in experimental hall

Micromegas as parasitic of PPACs


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Signals during three daysWe observed signals at: 13.5 keV, 22 keV, 56 keV, 80 keV, 200 keV, 200 eV???


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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 33S.

• 2 samples of 10B4C back-to-back (to study the effect).

• 2 blank samples back-to-back.


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THANK YOU FOR YOURATTENTION


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63Cu(n,) -> Q=1715 keV (69%)63Cu(n,p) -> Q=715 keV50Cr(n,) -> Q=319 keV (2%)33S(n,p) -> Q=533 keV17O(n,) -> Q=1817 keV (0.03%)47Ti(n,p) -> Q=182 keV (7%)47Ti(n,) -> Q=2189 keV63Cu(n,) -> Q=1715 keV

Elastic scattering from H

11 33 S(n, ) Cross Section: Implications for Neutron Capture Therapy and Astrophysics Javier Praena...

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