SRD1000 superconductive reference device

The SRD1000 sensor provides up to 13 stable reference points for thermometry between about  10 mK and 10 K. The points are established by the superconducting to normal transitions of samples of various materials.  Lesser points may be included in a specific device to cover only the main temperature range of a set-up.

  • Adapter [1] eases and secures the mounting of the sensor in a cryogenic set-up; 

  • A Cryoperm / niobium shield [2] reduces ambient magnetic fields near the reference samples to minimise shifts of the transition temperatures. An optional internal compensation coil allows analysis and compensation of residual fields; 

  • The shielded signal leads [3] of the primary, secondary and compensation coils are terminated by connectors that contain filters [4,5,6] to suppress the influence of rf-interference;

  • Calibration of a sensor and electronics is performed by either HDL or PTB, Berlin.

  

  
Characteristics of the 13 reference points, with typical values for:  
Tc  = transition temperature of the reference material;
Wc = transition width (temperature interval in which the signal of the transition changes by 80%);
Uc  = estimate of the uncertainty in determining Tc related to the transition characteristics.

#

   (1) (2) (3) (4) (5) (6) (7) (8) (9) (10) (11) (12) (13)
 material    W Be Ir80Rh20 Ir92Rh08 Ir AuAl2 AuIn2 Cd Zn Al In V Pb
Tc  [mK] 15 21 30 65 98 145 208 520 850 1180 3400  4900 7200
Wc [mK] <0.2 <0.3 <0.5 <0.5 <0.5 <0.5 <1 <1 <2 <4 <4 <20 <6
Uc  [%] <0.3 <0.3 <0.3 <0.2 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1
 
Output voltage of the MIDS-20x electronics showing the transitions of a 13-point SRD1000 sensor.    
Example of an Ir92Rh08 reference point with TC = 65.38 mK and WC = 0.34 mK (output voltage V of the MIDS-20x electronics versus sensor temperature- measurements by PTB, Berlin).