Limitation of the RBS Technique

Exercise 1. Find the impact parameter and distance of closest approach for a-particle of 6.7MeV energy impinging on gold target. What will be the distance of closest approach if scattering angle is 90°. 

For scattering at a particular angle the alpha particle comes closest to the nucleus when its momentum is perpendicular to the radius vector from the nucleus. By using the conservation of energy and the conservation of angular momentum it is fairly straightforward to show that for 90° scattering the distance of closest approach is 

Exercise 2. Find the energy of the particles as well as the thickness of Au layer if the RBS spectrum contains 1,000 counts of a-particles backscattered from this Au layer Given Incident angle a = 0°, scattering angle 0 = 170°, E = 2 MeV, Af2 = 10 steridian, Q = 10 pC. 

9 = 170° for incident a-particles on Au target calculated using formula for d(j/dQ 

Exercise 3. The a-particles with kinetic energy lOMeV are incident on a gold foil of thickness 0.1 mm at a rate of 10 particles per second. A detector of area 10 m is placed at an angle of 30° to the direction of incident a-particles at a distance of 2 m from the foil. Calculate how many a-particles per second reach the detector Given the density of gold is 1.93 x 10 kg m . 

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The lead precursor in PbSe film deposition was lead acetate complexed with triethanolamine. The growth rate for PbSe was 0.18-0.16nm/cycle. The films were polycrystalline (i.e., cubic) without preferred orientation. The stoichiometry of SILAR-grown PbSe was found to be 1 1 within the limits of the RBS technique. Impurities detected were 5 at.% of oxygen and 8 at.% of hydrogen.103... 

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