Glossary for quantities in the Hamamatsu data sheets:<br> <br>
Sk : Cathode Sensitivity, unit = micro Amps per lumen <br>
Sp : Anode Sensitivity, unit = Amps per lumen <br> <br>
From these two quantities, the gain can be calculated as 
Sp / Sk (in units of 10^6, because
A over uA) <br><br>
Note the anode sinsitivity Sp here is measured with all channels ganged
together, namely the sum of 16 pixels.<br>
Also, the light is shed on the tube through a slit  with an aperture of
the size 18 mm times 18 mm,
bigger than the sensitive area. <br>
That means the tube photocathode is exposed to light 
uniformely over the entire cathode, independent of the position on the surface.
<br>
These two facts imply that the gain calculated in the way above 
is that of the average over the surface of the 
photocathode, <br>
or, the average of the 16 channels.

<br><br>

Idb : Anode dark current, unit = nA <br>
Skb : Cathode blue sensitivity (similar to Sk, but in particular to 
blue light) <br> <br>
All these quantities are measured with a standard tungsten lamp (2865 K) 
as a light source. 
<br>Also, the Corning filter CS 5-58 is
used to give blue light.
Tubes are applied with a HV of -800 V.
<br><br>