No abstract

No abstract

No abstract

The natural radioactivity due to the presence of (226)Ra, (232)Th and (40)K in selected building materials used in Jordanian building constructions has been measured using gamma-ray spectrometer with a Hyper Pure germanium detector. The average activity concentrations observed in different building materials ranged from 27.7 +/- 7.5 to 70.4 +/- 2.8, 5.9 +/- 0.67 to 32.9 +/- 3.9 and 30.8 +/- 0.87 to 58.5 +/- 1.5 for (226)Ra, (232)Th and (40)K, respectively. The activity concentrations of (226)Ra measured in fine aggregates was found to be among the highest values obtained in this work. The ranges of the calculated Ra-equivalent were found to be lower than those values recommended for construction materials (370 Bq kg(-1)). The average internal and external hazard indices were found to be <1. The average of the calculated annual gonadal equivalent dose was found to be 198 microSv y(-1). Results indicate no significant radiological hazards arise from using such materials in building construction.

The zero-degree ejected-electron spectrum for protons incident on He at 25 keV is examined experimentally using the COLTRIMS technique. The momentum distribution of the emitted electrons for the transfer ionization (TI) reaction channel is measured in coincidence with the momentum vectors of the recoil ion and the scattered projectile. The momentum distribution of the electrons emitted around zero degree in the forward direction for the TI reaction channel shows two prominent structures: the electron-capture-to-the-continuum (ECC) peak and the saddle-point peak. From the measured fully differential electron emission cross sections with respect to the scattering plane we can deduce that the main ECC formation mechanism is electron promotion via quasimolecular orbitals.