80 likes | 83 Views
This paper focuses on the characterization of 14N implanted targets used in experimental nuclear physics and nuclear astrophysics. The effect of implantation on the target surface is investigated using scanning electron microscope (SEM) and X-ray photoelectron spectroscopy (XPS) measurements.
E N D
Surface Characterization of 14N Implanted Targets Abhijit Bisoi Saha Institute of Nuclear Physics 1/AF Bidhannagar, Kolkata-64
Introduction In experimental Nuclear Physics, target is one of the essential ingredients for any type of measurements. a) Solid target. 1. Evaporated target 2. Sputtered target 3. Targets prepared by rolling from a pellet 4. Implanted Target. b) Gas target. In Nuclear Astrophysics, in most cases implanted targets are used because of its stability and purity (isotopically enrich ). 14N(p,γ)15O reaction is hampered by 15N(p,αγ)12C background reaction with 15N impurity in the target. The 14N implanted targets have a 15N depletion of about two order of magnitude.
Target preparation Simulation: Implanted energy and backing have been selected by the simulation code TRIM. Experiment: *No special treatment of the foil was undertaken to reduce contaminants in the foil.
Scanning Electron Microscope (SEM) Measurement • In order to investigate the effect of implantation on the surface of the target, a pure Ta sheet and an irradiated Ta sheet were characterized by SEM measurement. SEM Measurement: Target surface Before implantation After implantation
X-ray photoelectron spectroscopy (XPS) Measurement Target-I XPS spectrum (1486.6 eV (Al Kα) X-ray)for 14N implanted target. The peak corresponding to nitrogen is shown in the inset. Target-II
Conclusion • No Fluorine & Sodium peaks observed in Target-II. • Reduced Oxygen & Carbon contamination in Target -II. • Additional efforts have to be taken to remove all contaminants from the target. • Effort has to be made to extract quantitative estimation of 15N impurity present in these targets. Future plan: • Investigation of nitrogen distribution in the bulk of the material by using Rutherford Back Scattering (RBS) Spectroscopy or 278 keV 14N(p,γ)15O Resonance reaction.
Acknowledgement: The authors acknowledge Prof. M. Mukherjee, Prof. K.S.R. Menon, A. K. M. Maidul Islam, Souvik Banerjee and Jayanta Das for their sincere help and cooperation for XPS, SEM and EDX measurements and data analysis. References: [1] C. Rolfs and W S Rodney, Cauldrons in the Cosmos (University of Chicago Press) 1988. [2] S. Suethe et. al, Nucl. Instr. and Meth. A 260, 33 (1987). [3] H.Y. Lee et. al, Nucl. Instr. andMeth. B 267, 3539 (2009). [4] J. Cruz et. al, Nucl. Instr. and Meth. B 267, 478 (2009). [5] T.A.D. Brown et. al, Nucl. Instr. and Meth. B 267, 3302 (2009). [6] James F. Ziegler,http://www.srim.org [7] http://www.srdata.nist.gov/xps