Appendix C
Calibration
C.1 Inter-Calibration of Time Scales
To obtain a valid correspondence between MC step time and actual time, we
assume that the MC temperature is equal to temperature of the experiment in the
range 1.2K to 2K. We then plot the of generation-recombination time constant
obtained from fitting S(ω, T ) to τ (T )(ω = 0, T )/(1 + (ωτ ) b )) for both MC DSIM
τ MCDSI M (T ) and experiment τ experiment (T ) respectively with temperature T as the
implicit variable. We fit a linear curve to the plot with intercept =0 (Fig. C.1). The
slope of the linear fit gives us the correspondence between MC step and actual time:
1MC-step = 83±11 microseconds.
C.2 Calibration of Sensitivity
The transfer function C between pickup coil and SQUID is calibrated by driving a
small known flux T EST (φ 0 ) via a drive coil (inserted into the pickup coil) through
the pickup coil, and recording the corresponding SQUID output voltage VS. In this
case (Fig. C.2)
C =
V S
0.684
1
T EST (φ 0 )
(C.1)
We find that C=0.015. The spectral density of magnetic-flux noise within the sample
is obtained
S (ω, T ) = S v (ω, T )/(C
2 ).
(C.2)
© Springer Nature Switzerland AG 2021
R. Dusad, Magnetic Monopole Noise, Springer Theses,
https://doi.org/10.1007/978-3-030-58193-0
71
Calibration
C.1 Inter-Calibration of Time Scales
To obtain a valid correspondence between MC step time and actual time, we
assume that the MC temperature is equal to temperature of the experiment in the
range 1.2K to 2K. We then plot the of generation-recombination time constant
obtained from fitting S(ω, T ) to τ (T )(ω = 0, T )/(1 + (ωτ ) b )) for both MC DSIM
τ MCDSI M (T ) and experiment τ experiment (T ) respectively with temperature T as the
implicit variable. We fit a linear curve to the plot with intercept =0 (Fig. C.1). The
slope of the linear fit gives us the correspondence between MC step and actual time:
1MC-step = 83±11 microseconds.
C.2 Calibration of Sensitivity
The transfer function C between pickup coil and SQUID is calibrated by driving a
small known flux T EST (φ 0 ) via a drive coil (inserted into the pickup coil) through
the pickup coil, and recording the corresponding SQUID output voltage VS. In this
case (Fig. C.2)
C =
V S
0.684
1
T EST (φ 0 )
(C.1)
We find that C=0.015. The spectral density of magnetic-flux noise within the sample
is obtained
S (ω, T ) = S v (ω, T )/(C
2 ).
(C.2)
© Springer Nature Switzerland AG 2021
R. Dusad, Magnetic Monopole Noise, Springer Theses,
https://doi.org/10.1007/978-3-030-58193-0
71