Disabling/Enabling Parts of the Detector

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The KGEDS_ENB word of the GEDS bank can be use to switch on/off parts of the detector. For example, to disable the PMT support structure (region 460 and 462 ):-

set bank geds 460 word 1 to 0
set bank geds 462 word 1 to 0

or better use the symbolic commands:-

$disable_geom $PSUP_OVL
$disable_geom $PSUP_IVL

However you cannot switch off the following which represent the ``core'' geometry:-

Region Type   Description 




100 		  D2O 


200 		  Acrylic Vessel 


300 		  H2O 


400 		  H2O near PMT panels 


410 		  Panel Zone


422..433 		  PMT outer volume and internal structure 


500 		  Outer darkness 

So, for example, you cannot switch off the Acrylic Vessel, but you could change the KGEDS_IDM word of its GEDS bank so that it was the same medium as say, the H2O, which has the same effect.

Before version 2.08, there was was a subtlety associated with enabling and disabling that, strictly speaking, made it was necessary to adjust volumes in the GEDS to take account embedded regions. This was to ensure correct weighting when picking points from a list of detector elements. As from 2.08, the method of picking has been changed so that the volumes are the true size; no allowance for embedding elements is made and so no adjustments are required. The only possible exceptions are in cases of the core geometry. For example, the Acrylic Vessel volume is that of the shell, not a sphere, for the D$_2$O sphere that embeds is hardwired into the pick code. However the core geometry cannot be disabled so again no adjustment is required.