Question

Researchers at IBM routinely use 2.50-MeV Het+ ions to analyze thin films using Rutherford backscattering. In a particular experiment, a 2.50-MeV *He ion beam is used to determine the thickness of a pure aluminum, 27AI, film. In this experiment, a surface barrier detector of area 10.0 cm² is placed 130 cm from the target at an angle of 170 degrees. A. Calculate the energy of the scattered 'Het+ ions that reach the detector. B. Calculate the solid angle of the surface barrier detector. C. The RBS spectrum is collected until 82.0 uC of total integrated beam charge is collected in a Faraday cup that immediately follows the foil. Assuming that the film is sufficiently thin so that charge exchange effects are negligible, calculate the number of "He** ions that struck the target during the experiment. D. Calculate the Rutherford scattering cross section for 2.50-MeV 'He ions on an 13 Al target at 170 degrees. E. What would be the thickness of the aluminum foil in atoms/cm² if the aluminum peak in the RBS spectra for this experiment contained 13,000 counts?

Answer 1

Muz con a) žm, uz = a Zitzel. (18) b Men B. 1709 170° = 2*9x109 x 4x27 X1 1 x 105 102, * *6+(120) = 8.37 x 10-28 Joule = 8.37 x 104 1.602 x 1013 = 5.22 X1015 mer der = 2Tsino doo id=dr = 2T/dinado = 211 - caso) 170° = 2T (Coso - cos 170) = 2T X 61-60. = 20 x 1.98 = 3.96 T. = 12, Z, el 12 cosec of 4TT. MUL T48 27x11.6*10-19 2 x 2.50 x 1,6x1013 Jessee 1707 = 3.16 *10-14 = 3.16 10 19 x Jar = 3.16 8 10 19 X 3.967 - 3.92 x 10-13 con metre? D. do 9 x 10 a This is Rutherford's shattering cross section