Lakeshore 336, User Manual

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5.10.2 SoftCal™ Accuracy With DT-400 Series Silicon Diode Sensors 89
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5.10.2 SoftCal™
Accuracy With DT-400
Series Silicon Diode
Sensors A SoftCal™ calibration is only as good as the accuracy of the calibration points. The
accuracies listed for SoftCal™ assume ±0.01 K for 4.2 K (liquid helium), ±0.05 K for
77.35 K (liquid nitrogen), and 305 K (room temperature) points. Users performing the
SoftCal™ with Lake Shore instruments should note that the boiling point of liquid
cryogen, though accurate, is affected by atmospheric pressure. Use calibrated stan-
dard sensors if possible.
One-point SoftCal™ calibrations for applications under 30 K are performed at liquid
helium (4.2 K) temperature. Accuracy for the DT-470-SD-13 diode is ±0.5 K from 2 K
to <30 K with no accuracy change above 30 K.
Two-point SoftCal™ calibrations for applications above 30 K are performed at liquid
nitrogen (77.35 K) and room temperature (305 K). Accuracy for the DT-470-SD-13
diode sensor is as follows:
Three-point SoftCal™ calibrations are performed at liquid helium (4.2 K), liquid nitro-
gen (77.35 K), and room temperature (305 K). Accuracy for the DT-470-SD-13 diode
sensor is as follows:
FIGURE 5-8 Acceptable temperature range for DT-400 series silicon diode SoftCal™ sensors
SoftCal Point One
Liquid helium
boiling point
4.2 K
SoftCal Point Two
Liquid nitrogen
boiling point
77.35 K
SoftCal Point Three
Room temperature
point
305 K
2 – 10 K 50 – 100 K 200 – 325 K
325 350 300 275 250 225 200 175 150 125 100 75 50 25 0
±1.0 K 2 K to <30 K (no change below 30 K)
±0.25 K 30 K to <60 K
±0.15 K 60 K to <345 K
±0.25 K 345 K to <375 K
±1.0 K 375 to 475 K
TABLE 5-6 2-point SoftCal™ calibration
accuracy for DT-470-SD-13 diode sensors
±0.5 K 2 K to <30 K
±0.25 K 30 K to <60 K
±0.15 K 60 K to <345 K
±0.25 K 345 K to <375 K
±1.0 K 375 to 475 K
TABLE 5-7 3-point SoftCal™ calibration
accuracy for DT-470-SD-13 diode sensors