Dead-time is handled somewhat differently with the URSA-II than in most other MCAs because the spectrum is not accumulated within the device. Each pulse height measurement is transmitted to the PC as it is taken (as a three-byte packet) and that transmission time is responsible for the majority of the "dead time," as the processor cannot measure a pulse height simultaneously with sending out data.
However, the processor can keep track of the number of counts that exceed the threshold, whether pulse-height analyzed or not. So the number of "unanalyzed pulses" is included with the transmitted packet, and the spectrum is adjusted accordingly. All that is a long way of saying that it automatically compensates for dead-time losses... In most cases at moderate count rates the corrections are practically negligible. Under the Misc menu is a setting where you can disable the dead time correction. Oh, and therefore count times are always real/clock time.
It does display the percent dead time, and has a bunch of other features (including the ability to import BNC/Termo N42 files). Alas, the manual has not kept up with all of the changes. Interested in being hired to write a manual?
Paul R. Steinmeyer
Health Physicist, Electronics and Software Design
Radiation Safety Associates, Inc.
PO Box 107/19 Pendleton Drive
Hebron, CT 06248