A small, battery-powered ultraviolet radiation detector was developed using three spectrally distinct photodiodes housed in a weatherproof enclosure (cylinder with r=16mm, h=15mm) under an acrylic window. Each induced photocurrent (plus a temperature reading) was amplified and conditioned electronically, converted to a digital number and stored in a non-volatile memory space, contained in another small enclosure (cuboid, 100x70x30mm). Each reading was time-stamped. The detector was characterised in the laboratory to determine its spectral sensitivity, angular response, linear response, temperature dependency and dark current. It was calibrated in natural sunlight, at a range of solar zenith angles, ozone column amounts and cloud conditions, against a Bentham DTM300 spectroradiometer. The results showed it to approximate the irradiance weighted by four distinct biological action spectra with an overall accuracy of 20%. It was tested in a number of field settings and shown to operate in a range of environmental conditions and provide data that had scientific relevance. A number of the detectors were used in two personal dosimetry experiments. The data revealed distinct exposure patterns between occupational and recreational days, and highlighted the strong influence of behavior on both ultraviolet exposure rates and integrated doses. Further, it was shown that the relative balance of previtamin D photosynthesis and erythemally weighted irradiance is not dependent on solar zenith angle when one considers a population with varying behaviors in a variable climate.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:498673 |
| Date | January 2009 |
| Creators | McNulty, Liam |
| Publisher | University of Manchester |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
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