Introduction: In radiation therapy centers across Iran, protection of normal tissues is usually accomplished by either Cerrobend or lead block shielding. In this study, the influence of these two shielding methods on central axis dose distribution of photon beam a Cobalt unit was investigated in clinical conditions. Materials and Methods: All measurements were performed for 60Co γ-ray beams an...

Background: Monte Carlo simulations play a vital role in the calculation of the necessary shielding both for neutrons and photons. Advanced and simple shielding materials against neutron and gamma rays were compared by simulation using the MCNB4B Monte Carlo code. The simulations were carried out for the three common neutron sources, namely the 252Cf, the 241Am/Be and the DD neutron generator w...

Background: Polymer composites when reinforced with heavy metals in the form of micro/nano particles are efficient gamma- and X-ray shielding materials providing such advantageous features as cost-effectiveness, light-weight factor, flexibility, non-toxicity, conformability over conventional shields. Materials and Methods: In this paper the influence of weight percentages and particle sizes of ...

Crack tip shielding phenomena, whereby the "effective crack-driving force" actually experienced at the crack tip is locally reduced, are examined with reference to fatigue crack propagation behavior in metals, composites and ceramics. Sources of shielding are briefly described in terms of mechanisms relying on the production of elastically constrained zones which envelop the crack (zone shieldi...

Effective radiation shielding is imperative to safe operation of modern Medical Cyclotrons producing large activities of short-lived radioisotopes on a commercial basis. Like the containment shielding of Medical Linear Accelerators (1), the optimal shielding design of Medical Cyclotrons demands a careful balance between the radiological, economical and often the sociopolitical factors. One is r...

Radar reflectivity (Zh), differential reflectivity (Zdr), and specific differential phase (Kdp) measured from the operational, polarimetric weather radar located in Trappes, France, were used to examine the effects of radar beam shielding on rainfall estimation. The objective of this study is to investigate the degree of immunity of Kdp-based rainfall estimates to beam shielding for C-band rada...

Action of electric and magnetic fields and their interaction effects are the basis of operation of every electrical and electronic instrument. But such action fields could also cause serious problems to the functioning of those instruments if they act on them unnecessarily, to the extreme, failure of the system may also occur. To avoid such unpleasant consequences arising out of unwanted electr...

While shielding in collisional, strongly magnetized (one-dimensional) plasmas obeys the standard Debye result, shielding in collisionless, immobile ion plasmas is far more complex than commonly believed. In some circumstances, the plasma will antishield a positive test charge; i.e., the plasma becomes more positive in the neighborhood of a positive test charge. When shielding does occur, it res...

In this paper, we propose alternate self shielding to remove critical transitions of on-chip global interconnect. Our proposed method alternates shield and signal wires cycle by cycle. The conventional self-shielding methods need additional wires to remove critical transition by encoding. The proposed alternate self-shielding, however, requires no additional wires. We evaluate our method by sim...

The shielding for 14-MeV neutrons from a D-T generator at SLAC needs to be optimized in terms of shield thickness and cost. Shielding calculations were made using the MCNP4B Monte Carlo code and the ENDF/B-VI cross section set. A few materials were studied: iron, borated polyethylene, three types of normal and heavy concrete, and mixtures of iron and borated polyethylene. The effects of shieldi...