Recoil Atom Yield in 100Mo(p, x)99Mo During 28 MeV Proton Irradiation of Nanosize Molybdenum Layers

According to the Szilard–Chalmers effect, 99Mo recoil atoms can be obtained in nuclear reactions and recorded in a collector. Knowledge of the dependence of the yield of 99Mo atoms on the thickness of the molybdenum layer is necessary for their efficient collection. The yield of 99Mo recoil atoms from molybdenum nanolayers in the nuclear reaction 100Mo(p, x)99Mo was measured as a function of the thickness of the nanolayer. Nanolayers of metallic molybdenum were fabricated by magnetron sputtering on sapphire plates. The measurements were performed after the nanolayers were irradiated by 28 MeV protons in the U-150 cyclotron. The yield of 99Mo recoil atoms for 38–205 nm thick nanolayers was 65–8%. It was found that the maximum 99Mo yield obtains with molybdenum layer thickness 80 ± 5 nm. It was found that the free path of 99Mo recoil atoms in native metallic molybdenum is equal to 34 ± 9 nm.