Hi Archana,
I don’t use any defect detection rate. Personally, I don’t think it is ok to define this rate because defects have different severity. You can find 10 minor bugs in one day and 2 major bugs in the next day. Of course, there can be used metrics with various weights for defects characteristics (severity, likelihood etc.) but you risk focusing more on this metrics/rates and less on testing and quality.
I have seen managers that use this defect detection rate as a target for the testing team during a specific iteration/sprint, but the rate is set by the managers and not by the testers
Regards,
Alin