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Standard curve Not applicable
Recommended excitation1 20 µV (0.05 K to 0.1 K); 63 µV (0.1 K to 1 K); 10 mV or less for T > 1 K
Dissipation at recommended excitation
10–13 W at 0.05 K, 10–7 W at 4.2 K (temperature and model dependent)
Thermal response time 200 ms at 4.2 K, 3 s at 77 K
Use in radiation Recommended for use in ionizing radiation environments— Click here for more information
Use in magnetic field Because of their strong magnetoresistance and associated orientation effect, germanium sensors are of very limited use in magnetic fields—Click here for more information
Soldering standard J-STD-001 Class 2
 Short term2 Long term3
4.2 K±0.5 mK±1 mK/yr
77 K ±10 mK/yr
1Recommended excitation for T < 1 K based on Lake Shore calibration procedures using an AC resistance bridge—for more information refer to Appendix D andAppendix E
2 Short-term reproducibility data is obtained by subjecting sensor to repeated thermal shocks from 305 K to 4.2 K
3 Long-term stability data is obtained by subjecting sensor to 200 thermal shocks from 305 K to 77 K
Range of Use
GR-50-AA <0.05 K5 K
GR-300-AA 0.3 K100 K
GR-1400-AA 1.4 K100 K
Calibrated Accuracy
 Typical sensor accuracy4
0.05 K±5 mK
0.3 K ±5 mK ±4 mK
0.5 K±5 mK±4 mK
1.4 K ±6 mK ±4 mK ±4 mK
4.2 K±6 mK±4 mK±4 mK
77 K±25 mK±15 mK
100 K±32 mK±18 mK
4 [(Calibration uncertainty)2 + (reproducibility)2 ] 0.5 for more information seeAppendices B D, and E
Typical Magnetic Field-Dependent Temperature Errors5 ΔT/T (%) at B (magnetic induction)
T (K)2.5 T 8 T14 T
4.2-5 to -20-30 to -55-60 to -75
10-4 to -15-25 to -60-60 to -75
20-3 to -20-15 to -35-50 to -80
5 Long axis of thermometer parallel to applied field
Typical Resistance Values
GR-AA Typical resistance at 4.2 K Typical resistance range at 4.2 K
50 30 Ω9 Ω to 65 Ω
300 95 Ω15 Ω to 155 Ω
14001750 Ω350 Ω to 6500 Ω
Temperature Response Data Table (typical)—See Appendix G for expanded response table
0.05 K 35000-3642000-5.203
0.1 K2320-71860-3.101
0.2 K364.6-4043-2.218
0.3 K164.0-964.0-1.76335180-512200-4.367
0.5 K73.75-202.9-1.3765443-34800-3.197
1.0 K33.55-31.33-0.9340875.7-1901-2.170
1.4 K24.73-13.15-0.7445448.6-581.3-1.81435890-94790-3.698
2.0 K19.32-6.167-0.6383248.8-187.4-1.50711040-16670-3.020
4.2 K13.66-1.036-0.318694.46-26.56-1.1811689-861.9-2.144
10 K33.20-3.965-1.194252.8-61.95-2.451
40 K7.789-0.2351-1.2079.569-0.4489-1.876
77.4 K3.504-0.0496-1.0963.545-0.0501-1.093
100 K2.716-0.0238-0.87542.796-0.0208-0.7441
Proper Selection of Germanium Sensors for Use Below 1 K
Germanium resistance thermometers are often classified according to their 4.2 K resistance value. However, for devices to be used below 1 K, there is no close correlation between the 4.2 K resistance and the suitability of the device as a thermometer. As a result, the Lake Shore low resistance germanium sensors (GR-50-AA and GR-300-AA) are classified according to their lowest useful temperatures, not their 4.2 K resistance values.
The resistance vs. temperature behavior for these devices is typical of all the germanium sensors. As the temperature is lowered, both the resistance and sensitivity (dR/dT) increase logarithmically. The lowest useful temperature is generally limited by the rapidly increasing resistance and the difficulties encountered in measuring high resistance values.
The following recommendations are made concerning the optimum temperature range for using these devices:
GR-50-AA0.05 K to 1.0 K
GR-300-AA0.3 K to 100 K
Increasingly better temperature resolution is achievable at lower temperatures.
In general, it is recommended you do not purchase a device which has a lower temperature limit than required, since some sensitivity (dR/dT) will be sacrificed at the higher temperatures. For example, a GR-300-AA will have more sensitivity at 1 K than a GR-50-AA.
Physical Specifications
 MassLead typeInternal
395 mg4 color coded phosphor bronze with heavy build polyimide, attached with epoxy strain relief at sensor
Helium 4 (4He) at =500 Ω, air at < 500 Ω
Doped germanium chip mounted strain-free in a gold plated cylindrical copper can
Germanium Calibration Ranges