X-ray Production By Cosmic Muons

Muons have a small cross section for interactions and high energy, so they are very penetrating and give the significant contribution to the gamma spectra of Ge detectors, even in deep underground laboratories. One of the muon interaction effects with material is X-rays production. Having in mind that gold is often used as a detectors component, in this paper the production of X-rays in gold sample is analyzed by using an coincidence system based on plastic scintillation detector and Ge detector. The Au disc-shaped sample with mass of 40.6 g, radius 3.34 cm and 0.06 cm thickness was inside 12 cm thick lead shield of extended range HPGe detector. The plastic detector of 0.5 x 0.5 x 0.05 m dimensions was placed above the lead shield at the distance of 32 cm from detector endcap. The producing rate of Kα rays per Au mass unit from coincidence gamma spectrum is determined as R ≅7.1 x 10-4 g-1s-1. Taking in account the measured muon flux of Φ=54 s-1m-2, the muon cross section σKα≅ 43 Barn, for Au Kα X-rays production is calculated. Also, the cross sections of X-ray production by cosmic muons in lead and tungsten are measured. Unexpectedly, the results obtained did not reveal Z dependence in the Z= 74-82 region