The New Norm
The New Norm
We will be sharing our U.S. Patented, U.S. and International Patent Pending Advancements in the form of a series of white papers such as:
OPTIMIZATION of LEAD-FREE, COST-EFFECTIVE POLYMERIC SHIELDING COMPOSITES for ATTENUATION of ELECTROMAGNETIC RADIATION
OPTIMIZATION of LEAD-FREE, COST-EFFECTIVE METALLIC SHIELDING COMPOSITES for ATTENUATION of ELECTROMAGNETIC RADIATION
OPTIMIZATION of LEAD-FREE, COST-EFFECTIVE HYBRID SHIELDING POLYMERIC and METALLIC COMPOSITES for ATTENUATION of ELECTROMAGNETIC RADIATION
Wilhelm Rontgen originally discovered X-rays by accident at the end of the 19th century. We now know that X-rays, Gamma Rays, etc... are a subset of the Electromagnetic Spectrum, which spectrum is the broadest ranging physical phenomena known to man. In the physical sciences its importance parallels the role of skin, as the human body's largest muscle, to a human’s well being.
As shown in Figure 1, it extends from waves with wavelengths greater than 100 centimeters to wavelengths smaller than 10-17 centimeters. At the smaller wavelengths, the radiation should be considered to be small wave packets individually named Photons and collectively named Quanta by their discoverers Planck and Einstein.
Electromagnetic Radiation consists of transverse waves which travel at the speed of light where Frequencies (f), Energies (E), and Velocities (c), are interrelated by Planck’s constant (H), and Wavelength (λ) as follows E = Hf and c = f λ. By substitution the spectrum can be shown to cover Frequencies from 1000 hertz to over 1024 hertz and Energies from less than 1.0 Micro Electron Volts to over 10 Million Electron Volts.
As shown in Figure 1, the spectrum as we transverse from large waves to small waves covers a range of phenomena which we observe and use everyday, namely; Radio/TV/ Radar/Microwave/Infrared/Visible.
The spectrum’s importance is self-evident. Subsequent to Roentgen's discovery of X-rays, theoretical and experimental physicists, Bohr, Planck, Einstein, Compton, and Schrodinger, were successful in formalizing Quantum Physics Theory to explain observed phenomena at smaller wavelengths.
In essence, the intensity of an Electromagnetic Beam, X-ray, Gamma Ray, etc… is reduced as it passes through a material because of collisions between the beam’s photons and atoms of the material.
The beam is said to be attenuated because the collisions result in the removal and scattering of photons; hence, reducing and changing the energies of Photons that pass through. The main processes of removal and scattering as outlined were discovered by Einstein and Compton and are aptly called Einstein’s Photoelectric Effect and Compton’s Scattering Effect.
To better appreciate the complexity of developing formulations to maximize attenuation, it is worth recapping existing models. For simplicity, consider what happens when an Electromagnetic Beam, X-ray, Gamma Ray etc… strikes an attenuating material as depicted in Figure 2.
Assuming that the incident beam consists of photons of a single X-ray energy the attenuation (i.e. the reduction in the number of photons) in the exiting beam can as experimentally demonstrated represented by;
Nο - N = μ N Δ x
Where No and N are the number of photons in the incident and transmitted beams, Δx is the thickness of the attenuator and μ is a constant called The Linear Attenuation Coefficient, which is characteristic and specific of the attenuation material. By integrating the above expression for the complete attenuator thickness (X) we can develop the equation;
N = Nο exp ( -μ x )
Where we notice that the reduction in transmitted, photons are exponentially dependent upon the value of the Linear Attenuation Coefficient and are more prevalent as the value of μ increases. If we multiply the number of photons by their respective energies to express the above relationship in terms of intensities we can write;
I = Io exp ( -μ x )
Where I and Io are the transmitted and incident radiation intensities.
It has also been experimentally demonstrated that The Attenuation Coefficient, μ, is dependent upon the atomic number of the attenuation material and the energy of the radiation beam, while total attenuation is also dependent upon the density and thickness of the attenuation material.
These interrelated and controlling attenuation factors all need to be synchronized and optimized under appropriate simulated end use conditions if optimal attenuation products are to be forthcoming per specific application.
ARTEMIS Shielding is committed to developing these products to fulfill the end use requirements of Industrial, Testing, Medical, Nuclear, and Experimental facilities.