(Written by Vladimir Horvat - updated on October 20, 2021)
T=0 check box does not really belong in the Calibration factor group, but it was placed there because space was available. When T=0 check box is checked, SEUSS will ignore the actual value of the T coordinate and recalculate effective fluence and effective LET as if T were zero.
This feature was introduced for users who mount their devices directly on the platter, facing the vacuum window, without realizing that the platter had been positioned at a non-zero value of T. Checking the T=0 box saves them the trouble of repositioning their setup on the platter. The catch is that the box will be unchecked every time the SEUSS window opens, so that the users will have to make sure that the T=0 box is re-checked every time that happens, or at least before eeach run.
T=0 box can be checked and then unchecked (or vice versa) to force SEUSS to recalculate the beam parameters after switching from standard calculations to legacy mode or vice versa.