I have done some additional measurements and the results show as follow.
http://iga.iis.u-tokyo.ac.jp/tmp/test02.gif Fluorescent lamp (Measurement)
http://iga.iis.u-tokyo.ac.jp/tmp/test04.gif UV lamp (Measurement)
The results indicate the UV lamp has different diffuse characteristics
compared with common fluorescent lamps if the UVC sensor is cosine corrected
well as written in the sensor. If there is no problem with UVC sensor, it
might be not easy to model UV lamp with RADIANCE.