High purity plastics greatly improve the propagation of radiation-induced light

Nov 08, 2013
High purity plastics greatly improve the propagation of radiation-induced light
Highly-purified Polystyrene

Japanese researchers have reported major improvements in the propagation of light generated by radiation in highly purified plastics. The research was published in the issue of Applied Physics Letters on October 16, 2013.

Plastics that emit light when exposed to radiation are widely used in particle and nuclear physics experiments, and have been integral to radiation measurements in decontamination operations such as that in Fukushima Prefecture. A better understanding of the behavior of light emitted by plastics because of radiation will enable improved measurements of radiation or radioactivity.

This research team manufactured high-purity (>99.9%) polystyrene plastic that exhibits a much greater propagation distance for ultraviolet light than that of general-use polystyrene. Additionally, in-depth analysis of the ultraviolet revealed that values for the refractive index that were based on the longer-wavelength sodium D-line (589nm) were inaccurate. Instead, the team calculated a highly reliable and much more accurate "effective refractive index" that considers the wavelength distribution of light generated by the radiation.

These findings will contribute significantly at the fundamental level to the design of light propagation in radiation measurement devices, and will have far-reaching effects from particle physics experiments to optical fibers (e.g., scintillation fibers or wavelength shifters) that are used in high-performance radiation measurements and decontamination cleanup.

Research Methods and Findings

Basic data that characterizes the propagation of light generated by radiation includes the light attenuation length (defined as the distance in which the light intensity decreases by 0.36), the reflectivity, and the refractive index. The attenuation length of in normal polystyrene plastic is only 1mm. The research team produced highly-purified polystyrene (>99.9%) to study in greater detail the behavior of light produced by radiation. The attenuation length of the highly purified polystyrene was much longer (41.6mm) than that found in general-use polystyrene. Additionally, the group devised a mathematical function that goes beyond the standard index based on the sodium D-line and describes an "Effective Refractive Index" (Neff=1.67) that considers the entire spectrum of light generated by radiation. By doing so, they can increase the accuracy in radiation measurements. This function is generally applicable to other materials that generate light.

Spillover Effects

This research has provided a better understanding of the behavior of light in plastics, and a more comprehensive understanding of the nature of light produced by radiation. In particular, applications using plastic optical fibers have dramatically improved the reliability of data based on outputted values, as well as in the initial values that are used in simulations to replicate the behavior of . Thus, higher performance can now be realized for the measurement of radiation or radioactivity.

Explore further: Discovery of a new mechanism for wavelength conversion of light by a plastic material

More information: Hidehito Nakamura, Yoshiyuki Shirakawa, Hisashi Kitamura, Nobuhiro Sato, Osamu Shinji, Katashi Saito and Sentaro Takahashi. "Light propagation characteristics of high-purity polystyrene." Applied Physics Letters, 103, 161111 (2013)dx.doi.org/10.1063/1.4824467

add to favorites email to friend print save as pdf

Related Stories

Improving light and heat spectra measurements

Oct 30, 2013

Whether you want to investigate objects in space, characterize the quality of light sources, optimize photovoltaics modules or analyze chemical compounds, measuring the spectrum of light- or heat sources ...

Solar cells utilize thermal radiation

Nov 04, 2013

Thermal radiation from the sun is largely lost on most silicon solar cells. Up-converters transform the infrared radiation into usable light, however. Researchers have now for the first time successfully ...

Recommended for you

New approach to form non-equilibrium structures

just added

Although most natural and synthetic processes prefer to settle into equilibrium—a state of unchanging balance without potential or energy—it is within the realm of non-equilibrium conditions where new possibilities lie. ...

Nike krypton laser achieves spot in Guinness World Records

1 hour ago

A set of experiments conducted on the Nike krypton fluoride (KrF) laser at the U.S. Naval Research Laboratory (NRL) nearly five years ago has, at long last, earned the coveted Guinness World Records title for achieving "Highest ...

Unleashing the power of quantum dot triplets

5 hours ago

Quantum computers have yet to materialise. Yet, scientists are making progress in devising suitable means of making such computers faster. One such approach relies on quantum dots—a kind of artificial atom, ...

Chemist develops X-ray vision for quality assurance

5 hours ago

It is seldom sufficient to read the declaration of contents if you need to know precisely what substances a product contains. In fact, to do this you need to be a highly skilled chemist or to have genuine ...

The future of ultrashort laser pulses

6 hours ago

Rapid advances in techniques for the creation of ultra-short laser pulses promise to boost our knowledge of electron motions to an unprecedented level.

User comments : 0