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Germanium Specifications

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 — 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 — 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

1 Recommended excitation for T < 1 K based on Lake Shore calibration procedures using an AC resistance bridge — for more information refer to Appendix D and Appendix 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

 Minimum limit Maximum limit
GR-50-AA <0.05 K5 K
GR-300-AA0.3 K100 K
GR-1400-AA1.4 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 see Appendices 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
5030 Ω9 Ω to 65 Ω
30095 Ω15 Ω to 155 Ω
14001750 Ω350 Ω to 6500 Ω

Temperature response data table (typical)

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

Expanded response table

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 atmosphereSensor materials
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 ΩDoped germanium chip mounted strain-free in a gold plated cylindrical copper can

Germanium calibration ranges