A thin colorless radiochromic diacetylene monomer sensor coated on a transparent polyester base undergoes solid-state polymerization via free radical mechanisms when irradiated with ultraviolet 266 nm wavelength, x- and gamma rays, and high-energy electron beam irradiation. The radiation-induced polymerization reaction leads to the formation of 1, I-trans additions as polyconjugations along the ladder-like polymer chains. As a result, the colorless, transparent films responds to ultraviolet and to ionizing radiation by turning deep-blue, with an absorption spectrum that exhibits two distinct absorptions bands (lambda(max), = 675 nm and 610 nm). Pulse radiolysis and flash photolysis techniques were used to measure the kinetics of the polymerizaton propagation reactions. The pulsed-electron-induced propagation of polymerization has an observed first-order rate constant of the order of 10(3) s(-1), followed by much slower blue-shift of the primary absorption band (lambda(max) = 675 nm --> 660 nm). The activation energy of the polymerization was found to be approximate to 50 kJ mol(-1). The fast kinetics of the UV-induced polymerization is faster by about one order of magnitude (k(obs) = 1.5 x 10(4) s(-1)). The film can be utilized for optoelectronics, remote sensing, and radiation dosimetry.

New transparent radiochromic films, GafChromic MD-55 and NMD-55, which turn from colourless to deep blue upon irradiation, have been designed particularly for measuring radiation therapy absorbed doses (1 Gy to 100 Gy). They are also useful for high resolution mapping of dose distributions, radiographic imaging, treatment planning dosimetry, beam penumbra measurements, and interface dosimetry with ionising photons, electrons and protons. The gamma ray responses are linear with dose in terms of increase of optical absorbance at 670, 633, and 600 nm and are independent of absorbed dose rate and relative humidity. The radiochromic images show a slight gradual post-irradiation increase in absorbance especially during the first 24 h. In addition, there is a small but predictable variation of sensitivity with temperature, both during irradiation and during spectrophotometry. The films also have a slight sensitivity to ultraviolet radiation (250 to 350 nm) in direct sunlight. Experiments with X ray beams show no appreciable energy dependence relative to dose in water at photon energies greater than 100 keV, but they have a sensitivity that gives readings of about 60% of the dose in water for photons at 20 to 40 keV.

In recent years data have been collected on conductive thermal-control paints, such as PCBZ and NS43G, in order to evaluate their stability to the space environment. In addition to being considered for spacecraft thermal control, the paints have been considered as an alternate material for use within on- orbit calibration systems. This will provide both an absolute calibration, by knowing the magnitude of the reflected light, and flat-field pixel-to-pixel comparisons within an instrument. Data are summarized here, as collected by the Cassini, Multi-angel Imaging SpectroRadiometer, and the Medium Resolution Imaging Spectrometer projects. Properties evaluated include absorptance, reflectance factor, electrical conductivity, thermal cycling, resistance, and environmental exposure stability.

A new radiation-sensitive imaging material, called GafChromic™ Dosimetry Media, offers advances in high-dose radiation dosimetry and high-resolution radiography for gamma radiation and electrons. The potential uses in radiation processing, radiation sterilization of medical devices, population control of insects by irradiation, food irradiation, blood irradiation for organ-transplant immuno-suppression, clinical radiography, and industrial radiography have led to the present sensitometric study over the breadth of the wide dynamic range of this new routine detector and imaging material, namely, absorbed doses from 10 Gy to 5 × 104 Gy. The thin-coated film is colorless before irradiation, and registers a deep-blue image upon irradiation, with two absorption bands at about 650 nm (major band) and 600 nm (minor band). The response to electrons, in terms of increase in absorbance per unit absorbed dose, is the same as that to gamma radiation within the estimated uncertainty of the measurements (± 5%, 95% confidence level). The spatial resolving power is > 1200 lines/mm. After the first 24 hours, the image is stable over many months (within ± 5% in absorbance), however, the system should be irradiated and analyzed at approximately the temperatures used during calibration, because of temperature dependence during irradiation and readout, and temperatures greater than 55°C should be avoided.

GafChromicTM Dosimetry Media is a thin film containing a colourless radiochromic imaging layer which produces a high resolution blue image when exposed to ionizing radiation. The high resolution of this film makes it a good candidate for use in dose distribution mapping with high spatial resolution.

A commercially-available electron recording medium has been examined in terms of response to ionizing radiation in the form of photons emitted from the radionuclides 137Cs and 60Co and accelerated electrons. Operational characteristics of the film have been evaluated using scanning visible spectrophotometry, color photometry, densitometry, and scanning densitometry. The effect of various irradiation parameters (absorbed dose, absorbed dose rate, and irradiation temperature) have been characterized over the absorbed dose range of 0.1 to 5 kGy. Principle attributes of the film appear to be dose-rate independence for a given source, a high degree of uniformity with respect to radiochromic dye coating, and reproducibility of individual film sample measurements. Methods of dosimetry system operation and potential applications are discussed, with emphasis on applications for food irradiation.