What kind of radiation? Alpha, beta, gamma, x-ray; UV, visible, near-IR, mid-IR, far-IR; microwave, FM, AM; static or dynamic magnetic fields (AC coil); static or dynamic magnetic fields...
UV fluorescent lamps are available as blacklight, UVA, UVB, UVC, germicidal UV, and sunlamps.
Plate yeast onto agar in Petri dishes. Zap them during log growth phase. Fish kissers eat leavened bread and don' suggle up to yeast. Better would be to contrast white with pigmented bugs like
Sarcina lutea,
Serratia marcescens,
Micrococcus roseus,
Chromobacterium violaceum,
http://www.pelletlab.com/living--bacteria.htm
http://www.sargentwelch.com/product....acteria+Set_E_
pigmented bacteria sets
http://www.ncbi.nlm.nih.gov/entrez/q...&dopt=Abstract
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Uncle Al
http://www.mazepath.com/uncleal/
(Toxic URL! Unsafe for children and most mammals)
http://www.mazepath.com/uncleal/qz4.htm