Novel 3-D printed radiation shielding materials embedded with bulk and nanoparticles of bismuth.

In the present study, a new type of radiation shielding material was developed by using a 3-D printing technique which enables to create a light radiation shielding materials of a great variety of shapes and dimensions. Micro and nano bismuth particles were incorporated as a filler between the inner layers of polylactic acid thermoplastic polymer (PLA Plastic) designed of the investigated 3-D printed prototypes to achieve the desired radiation attenuation. The effect of particle size on the attenuation parameters were studied over the energy range from 0.0595 to 1.41 MeV. The mass and thickness needed to reduce the intensity of the incoming radiation to half of its original value were determined experimentally for pure polymer (ABS Plastic), polymer with bulk Bi, and polymer with nano Bi. The results reveal that bismuth NPs with average particle size of about 17 ± 3 nm have a greater mass attenuation capability than normal bulk bismuth particles, meaning they are more efficient and a lighter shield can be produced. The enhanced shielding ability of nano bismuth particles was contributed to the excellent particle distribution, leading to an increase in the probability of photons interacting with the bismuth atoms. The bismuth NPs 3-D printed objects can be considered as a promising radiation shielding candidates and also could be utilized in manufacturing of radiation medical phantom.

Shielding Properties of Some Marble Types: A Comprehensive Study of Experimental and XCOM Results.

In this work, some marble types were collected from Egypt, and their shielding characteristics were estimated. Their rigidity, in addition to their elegant shape, led us to consider their use as a protective shield, in addition to making the workplace more beautiful. The mass attenuation coefficient (µ/ρ) was calculated for three types of marble (Breshia, Galala, and Trista) experimentally, using a narrow gamma ray source and high pure germanium (HPGe). The results obtained were compared with the XCOM program and indicated a very good agreement between the two methods. The linear attenuation coefficient (µ) was evaluated to calculate the half and tenth value layers. The maximum µ value of 1.055, 1.041, and 1.024 cm-1 was obtained for Breshia, Galala, and Trista, respectively, at 0.06 MeV. The mean free path for studying the materials was compared with other shielding materials and showed good results at different energy scales. The energy absorption (EABF) and exposure buildup factors (EBF) were determined at different mean free paths. The fast neutron removal cross section ΣR was calculated and expresses the ability of the marbles to slow down fast neutrons through multiple scattering. This is the ability of the marbles to shield fast neutrons.

Calibration of HPGe gamma-ray detectors for measurement of radioactive noble gas sources.

Measurements of radioactive noble gases are routinely made with gamma-ray spectrometers. This work describes the calibration of high purity germanium detectors provided by the full-energy-peak efficiency as a function of the gamma-ray energy. A comparison of measured efficiency values with a new, simplified method based on a direct mathematical method is given here.

Structural characterization of nickel oxide nanowires by X-ray absorption near-edge structure spectroscopy.

Nickel oxide nanowires modified by poly(vinylpyrrolidone) (PVP) were synthesized via a simple chemical pattern. For the first time NiO nanowires with diameters ranging from 40 to 100 nm with the expected ratio (length vs diameter) ranging from 54 to 90 were grown using a simple solution-phase approach (mild method). These nickel nanowires exhibited unique photoluminescence features and displayed a significant UV luminescence. X-ray absorption near-edge spectroscopy has been used to characterize the local Ni environment and identify the electronic structure. Comparing experimental and theoretical spectra at the Ni and O K edges, we determine the lattice distortion via the analysis of the characteristic preedge features and the multiple-scattering structures detected in the X-ray absorption near-edge structure spectra. The correlation between experimental features and the disordered or distorted local structures is also discussed.

Analytical formulae for well-type NaI (Tl) and HPGe detectors efficiency computation.

A straightforward analytical formulae for the computation of total and full-energy peak efficiencies of NaI (Tl) and HPGe well-type detectors are deduced. In addition, the attenuation of photons by the source container and the detector end cap materials is presented in a direct mathematical expression. Results are compared with previous treatments.

HPGe detector photopeak efficiency calculation including self-absorption and coincidence corrections for Marinelli beaker sources using compact analytical expressions.

Direct mathematical methods to calculate total and full-energy peak (photopeak) efficiencies, coincidence correction factors and the source self-absorption of a closed end coaxial HPGe detector for Marinelli beaker sources have been derived. The source self-absorption is determined by calculating the photon path length in the source volume. The attenuation of photons by the Marinelli beaker and the detector cap materials is also calculated. In the experiments gamma aqueous sources containing several radionuclides covering the energy range from 60 to 1836 keV were used. By comparison, the theoretical and experimental full-energy peak efficiency values are in good agreement.