Photographs of Front of Detector Front of detector Image in dark Image close-up The image is green with white flickers of background light in its “normal state”. When a particle goes through the detector, a “streak” of white light will be seen across the green background. The next 2 slides show pictures taken from video of the detector. In the first, the detector is sitting on a table in a lab. In the second, the detector is in a test beam.