The spacing of the atoms of a crystal is 159pm. A monoenergetic beam of neutrons directed normally at the surface of the crystal undergoes first order diffraction at an angle of 58 degrees from the normal.
What is the energy of each of the neutrons? (m neutron =1.675*10^-27kg, 1eV=1.6*10^-19J, h=6.626*10^-34 J*s)