Results

Using the parameters used previously, and $C_{eff}$ = 0.5, $\eta$ = 0.6, and $Trec$ = 100 K, we can make the following comparison of the variations of $Tcal$

Item	$T_{cab}$	$Trec$	$F_{eff}$	$C_{eff}$	$\eta$
Typical Error	2 K	10 K	0.01	0.02	0.02
Induced variation (in %)	0.7	0.3	1.3	2.0	-0.5

This shows that the maximum effect is from $C_{eff}$ if this method is used, from $F_{eff}$ otherwise. It also indicates that the ``reduced chopper'' calibration is not a good technique, but a switchable attenuator should be used instead.