DRAFT Light-tight Requirement

PROPOSED NEW REQUIREMENT:  The dark current or leakage current of any sensor (PMT, SSD  ladder , DPD) , or associated noise rate,  shall change by less than  50 %, relative to dark-room baseline, when LAT is exposed to a light source of on-orbit solar strength from any direction.


RATIONALE: LAT components are light sensitive.  Although there has been an attempt to provide light tightness in many cases at the subsystem or component level, there is no formal, system-level requirement for the LAT, as a whole, to be light tight.  This requirement corrects this oversight.  When it is adopted, it must then be flowed into the LAT system design and test plans.  The requirement has been worded to be clearly testable and directly relevant to the instrument performance.


updated 21 March 2004 10:03