Magnetic Flux Noise (MFN)

Fig. 18 Structure of the Magnetic Flux Noise Measurements.

About MFN

The following section is about the fluctuations of the magnetic system.

Fig. 19 Repeated hysteresis loops (Crosses).

Fig. 20 Repeated hysteresis loops (Plusses).

Signal Analyzer

These measurements have been performed with the SR785.

SR785 Signal Analyzer

The signal analyzer SR785 is in-situ calculating the Fourier transformation of a signal. This yields faster results and improved memory usage because the raw signal does not need to be saved. This also implies that the raw signal is not available for further analysis.

Fig. 21 SR785: Large field sweeps outside and covering the hysteresis.

Fig. 22 SR785: Field sweeps inside the hysteresis.

Influence of various parameters on the PSD

Temperature

Fig. 23 SR785: Field sweeps at different temperatures.

Sweeprate

Fig. 24 SR785: Field sweeps for different sweeprates.

Applied Current Amplitude

Fig. 25 SR785: Field sweeps with different applied currents.

SR830 Data Acquisition (SR830DAQ)

These measurements have been performed solely with the SR830 lock-in amplifier.

Time-Signals

The SR830 can be programmed to send automatically data to the computer. Using this feature it is possible to acquire the raw (unfiltered) data.

Fig. 26 SR830DAQ: Time-Signal’s KDEs at static positions (m446).

Fig. 27 SR830DAQ: Time-Signal’s KDEs at static positions (m447).

Fig. 28 SR830DAQ: Time-Signal at selected positions (m446).

Fig. 29 SR830DAQ: Time-Signal at selected positions (m447).

Fig. 30 SR830DAQ: Time-Signal at selected positions (m446).

Analysis Overview

Fig. 31 SR830DAQ: Analysis Overview (m446).

Fig. 32 SR830DAQ: Analysis Overview (m447).

Calculated PSD

Fig. 33 SR830DAQ: Field sweeps for different sweeprates.

Fig. 34 SR830DAQ: Field sweeps with different applied currents.

MFN: Signal Analyzer

Date

2019

Angle

90deg

Important

Every parameter can be researched in detail it the OneNote notebook 03: MFN

Important

We found out: Filling helium into the cryostat interferes with the electric wiring of the cryostat and makes measurements impossible for the near time.

Date

12. Juli 2019

Measurement Plan 9: after filling He, the temperature was not stable. I took 5 hours to be stable. choosing the sensitivity extremly depend on the temperature. It was on overload when choosing 5mV.

After stabalizing the temp, 5mV was OK.

Static Field

Important Measurements

Measurement Plan #11: different applied current for plusses

Together with Measurement Plan #5: Static field effect

Nr.	Struct	Temp	Dir	Position [mT]
360	Plusses	5	Down	25
361	Plusses	5	Up	-25
280	Crosses	30	Down	0
281	Plusses	30	Down	0
310	Empty	30	Down	0
282	Plusses	30	Down	-9.4
283	Crosses	30	Down	-9.4

First measurements at 90deg

Date

6. Juni 2019

Nr	Structure	Field (PM) [T]	freq-span [Hz]	avg	Gain
m274	C	1	50/ 12.5/ 3.125	30	20
m275	#1	1
m276	#2
m277	C	4
m278	#1
m279	C		1.5 (Long)
m280	C	0
m281	P
m282	P	-9.4 mT (down)
m283	C
m286	P	-2.824 mT (down)
m287	P	-0.0063 T
m288	P	0.01247
m289	P	0.015
m290	P	0.03
m291	P	-0.57246	1.5 / 0.8 (Long)
m292	P	-0.10422
m293	P	-4
m294	C	-4
m295	#1	-4
m296	#2	-4
m297	C	-2.824 mT
m298	C	-0.0063 T
m299	C	-0.5725	1.5 (Long)
m300	C	0.01247
m301	C	0.015

Measurement Plan #2

Date

13. Juni 2019

Nr	Struct	Field	Permanent?	F-Span	Avg	Time
m310	#1 Empty	0	PM	Mrz	30	90 min
m311		-572.5 mT	PM	12 / 6 / 3 / 1 / 0.78	30	500 min
m312		250 mT	PM	3.125, 1.5625Hz	30
m313		500 mT	PM	3.125, 1.5625Hz	30
m314		1.5 T	PM	3.125, 1.5625Hz	30
m319:		2 T	PM	1.56 / 0.78 Hz	30
m315	Crosses	250 mT	PM	1.56 / 0.78 Hz	30
m316		500 mT	PM	1.56 / 0.78 Hz	30
m317:		1.5 T	PM	1.56 / 0.78 Hz	30
m318:		2 T	PM	1.56 / 0.78 Hz	30

Moving Field

Date

13. Juni 2019

Sweeping the field from positive to negative \(B_{max}\).

Note

• C: Crosses

• P: Plusses

• #1: Empty Cross

Fig. 35 First field sweeps

Measurement Plan #2

Date

13. Juni 2019

Nr	Struct	Field From	Field To	SR [mT/min]	F-Span	Avg	Time [min]
m320	#1 Empty	2T	1 T	9,43	1,56	25	107
m321				4,7	0,78		214
m322		500 mT	-500 mT	9,4	1,56		107
				4,7	0,78		214
m323		1 T	-1 T	9,4	0,78		214
m324				4,7	0,39		407
m325	Crosses	2 T	1 T	9,4	1,56		107
m326:				4,7	0,78		214
m327:		500 mT	-500 mT	9,4	1,56		107
m328:				4,7	0,78		214
m329:		1 T	-1 T	9,4	0,78		214
m330:				4,7	0,39		407
m331:		500 mT	-500 mT	9,4	1,56	25	107
m332:		300	-300	2,8	0,78	25	214
m333:		750	-750	7	0,78	25	214
m334:		0.1	0.1	0.093	0,78	25	214
m335:	#1 Empty	500 mT	-500 mT	9,4	1,56	25	107
m336:	Plusses	500 mT	-500 mT	9,4	1,56	25	107
m337:		50 mT	-50 mT	0.934	1,56	25	107
m338:		25 mT	-25mT	0,46	1,56	25	107
m339:		0	0.5	4,6	1,56	25	107
	#1 Empty	25 mT	-25mT	0,46	1,56	25	107
	Plusses	5mT	-5mT	9.3e-5

index

m322; m327; m328

Fig. 36 Plan #2: Field sweeps inside hysteresis (m322/327/328).

Large Sweep Ranges

Temperature

\(T = 30~K\)

Nr.	Struct	From	To
320	Empty	2 T	1 T
325	Crosses	2 T	1 T
323	Empty	1 T	-1 T
329	Crosses	1 T	-1 T
322	Empty	.5 T	-.5 T
327	Crosses	.5 T	-.5 T
336	Plusses	.5 T	-.5 T
333	Crosses	.75 T	-.75 T
332	Crosses	.3 T	-.3 T
331	Crosses	.1 T	-.1 T

Plots

Different Sweep Rates

Important

• T = 30K

• Plusses

• Sweeps from \(-M_S \rightarrow -25 \rightarrow 25\) mT

Nr.	Rate (mT/min)
354	2
351	1
353	.25
352	.1

MFN: Lock-In

Date

Feb - Aug. 2020

Note

Ange set to 45deg and fixed there. Measurements

SR830 DAQ

45deg Measurements

Nr.	Struct	Angle	Voltage	Frequency	Temp	Preamp	Rate	Time	Dir	Limit	dB	timeconstant	Error
430	Plusses	45	2.5	17	30	False	8	600	Down	0.2	0.01	0.1	nan
431	Plusses	45	2.5	17	30	False	8	600	Up	0.2	0.01	0.1	nan
432	Plusses	45	2.5	17	30	True	16	1024	Down	0.1	0.0025	0.1	1
433	Plusses	45	2.5	113	30	True	16	1024	Up	0.1	0.002	0.1	nan
434	Plusses	45	2.5	113	30	True	32	512	Up	0.2	0.02	0.1	nan
435	Plusses	45	5	113	30	True	16	1024	Down	0.1	0.005	0.1	nan
436	Plusses	45	5	113	30	True	8	1024	Down	0.2	0.005	0.1	nan
437	Plusses	45	5	113	30	False	8	768	Up	0.15	0.005	0.1	nan
438	Plusses	45	5	113	30	False	4	2048	Down	0.1	0.01	0.1	nan
439	Plusses	45	5	113	30	False	16	1024	Down	0.1	0.005	0.1	nan
440	Plusses	45	5	113	30	False	32	512	Up	0.1	0.005	0.1	nan
441	Plusses	45	5	113	30	False	32	512	Down	0.1	0.005	0.1	nan
442	Plusses	45	5	113	30	False	4	2048	Up	0.1	0.005	0.1	nan
443	Plusses	45	5	113	20	False	8	2048	Down	0.1	0.005	0.1	1
444	Plusses	45	5	113	20	False	8	2048	Up	0.1	0.005	0.1	1
445	Plusses	45	5	113	10	False	2	2048	Down	0.1	0.005	0.1	1
446	Plusses	45	5	113	15	False	8	2048	Down	0.1	0.005	0.1	nan
447	Plusses	45	5	113	15	False	8	2048	Up	0.1	0.005	0.1	nan
448	Plusses	45	5	113	15	False	4	2048	Down	0.1	0.005	0.3	1
449	Plusses	45	5	113	15	False	4	2048	Up	0.1	0.005	0.3	1
450	Empty	45	5	113	15	False	8	1024	Down	0.1	0.005	0.3	nan
451	Empty	45	5	113	15	False	8	1024	Up	0.1	0.005	0.3	nan

Useful Measurements

Nr.	Struct	Angle	Voltage	Frequency	Temp	Preamp	Rate	Time	Dir	Limit	dB	timeconstant
430	Plusses	45	2.5	17	30	False	8	600	Down	0.2	0.01	0.1
431	Plusses	45	2.5	17	30	False	8	600	Up	0.2	0.01	0.1
446	Plusses	45	5	113	15	False	8	2048	Down	0.1	0.005	0.1
447	Plusses	45	5	113	15	False	8	2048	Up	0.1	0.005	0.1
450	Empty	45	5	113	15	False	8	1024	Down	0.1	0.005	0.3
451	Empty	45	5	113	15	False	8	1024	Up	0.1	0.005	0.3
452	Plusses	80	5	17	15	False	8	1024	Down	0.3	0.015	0.1
453	Plusses	80	5	17	15	False	8	1024	Up	0.3	0.015	0.1
456	Plusses	80	5	17	15	False	8	2048	STATIC	0	0	0.1

• 45deg

• Plusses

• 17 Hz / 2.5 V / 30 K (Best results)

• 113 Hz / 5 V / 15 K

• Empty

• 113 Hz / 5 V / 15 K

• 80deg

• Plusses

• 17 Hz / 5 V / 15 K

80deg Measurements

Date

July 2020

Initial 80deg measurements

Nr.	Struct	Angle	Voltage	Frequency	Temp	Preamp	Rate	Time	Dir	Limit	dB	timeconstant	Error
452	Plusses	80	5	17	15	False	8	1024	Down	0.3	0.015	0.1	nan
453	Plusses	80	5	17	15	False	8	1024	Up	0.3	0.015	0.1	nan
454	Plusses	80	5	17	15	False	8	2048	Down	0.15	0.005	0.1	1
455	Plusses	80	5	17	15	False	8	2048	Up	0.15	0.005	0.1	nan
456	Plusses	80	5	17	15	False	8	2048	STATIC	0	0	0.1	nan

Hint

Most useful are m452 and m453.

Note

m456 measured at vacant external field for a very long time. This allows access to very low frequencies.

Error

m454/m455 have experienced some problems during the measurement. The results are not useful.

Check for

• difference between τ = 100ms/30ms

• Empty Cross background reference @ 80deg * Empty Cross with/without gradiometry?

• Voltage difference (2.5 V / 5 V)

• Reproducability of 90deg signal analyzer measurements.

80deg missing measurements

Date

30.06.2020 - 09.07.2020

Nr	Struct	Frequency	Temp	Rate	Time	Dir	Limit	dB	timeconstant	Error
458	Plusses	17	15	8	2048	Down	.1	.005	.1	Unregular number of values
459	Plusses	17	15	8	2048	Up	.1	.005	.1	Unregular number of values
460	Plusses	17	15	8	2048	Down	.1	.005	.1	No values
461	Plusses	17	15	8	2048	Up	.1	.005	.1
462	Plusses	17	15	8	2048	Down	.1	.005	.1
466	Plusses	17	15	8	1024	Down	.1	.005	.03
467	Plusses	17	15	8	1024	Up	.1	.005	.03
468	Plusses	17	15	8	1024	Down	.1	.005	.1
469	Plusses	17	15	8	1024	Up	.1	.005	.1
470	Plusses	17	15	8	1024	Down	.1	.005	.01
471	Plusses	17	15	8	1024	Up	.1	.005	.01
472	Plusses	17	15	8	1800	Down	.1	.005	.1
473	Plusses	17	15	8	1800	Up	.1	.005	.1
463	Empty	17	15	8	2048	Down	.1	.005	.1
464	Empty	17	15	8	2048	Up	.1	.005	.1
474	Empty	17	15	8	1024	Down	.1	.005	.1
475	Empty	17	15	8	1024	Up	.1	.005	.1
476	Empty	17	15	8	1024	Down	.1	.005	.03
477	Empty	17	15	8	1024	Up	.1	.005	.03

Measurement Routines for EVE

[458 Routine] [461 Routine] [463 Routine] [465 Routine] [466 Routine] [470 Routine] Finishes 470 (after cut at 40mT for filling He) and starts 471/472 [475 Routine] Finishes 475 (after power shortage cut at 55mT) and starts 476/477

45deg remeasure missing measurements

Date

July 2020

The first time at 45deg not all needed information could be gathered. Going back to 45deg to remeasure some missing parameters.

Plusses (Repeat 430/431)

Nr	Struct	Voltage	Frequency		Temp		Rate		Time		Dir		Limit				dB	timeconstant				Comment
482	Plusses	5	17		15		8		1024		Down		.1				.005	.1				$` R_{22} = 13.5 kOmega `$
483	Plusses	5	17		15		8		1024		Up		.1				.005	.1				$` R_{22} = 13.5 kOmega `$
484	Plusses	2.5	17		15		8		1024		Down | .1 | .005| .1 | $` R_{22} = 13.5 kOmega `$
485	Plusses	2.5	17		15		8		1024		Up | .1 | .005| .1 | $` R_{22} = 13.5 kOmega `$
486	Plusses	5	17 | 15 | 8 | 1024 | Down | .2 | .01 | .1 | $` R_{22} = 5 kOmega `$
487	Plusses	5	17 | 15 | 8 | 1024 | Up | .2 | .01 | .1 | $` R_{22} = 5 kOmega `$
488	Plusses	5	17 | 15 | 8 | 1024 | Down | .2 | .01 | .03 | $` R_{22} = 5 kOmega `$
489	Plusses	5	17 | 15 | 8 | 1024 | Up | .2 | .01 | .03 | $` R_{22} = 5 kOmega `$

Empty Cross (17 Hz)

Nr	Struct	Voltage	Frequency	Temp	Rate	Time	Dir	Limit	dB	timeconstant
480	Empty	5	17	15	8	2048	Down	.1	.005	.1
481	Empty	5	17	15	8	2048	Up	.1	.005	.1
490	Empty	5	17	15	8	1024	Down	.2	.01	.1
491	Empty	5	17	15	8	1024	Up	.2	.01	.1
492	Empty	5	17	15	8	1024	Down	.2	.01	.03
493	Empty	5	17	15	8	1024	Up	.2	.01	.03

Attention

After finished measurements (untill m493), we discovered that the gate grounding (4-9) device (Yokogawa 7651 Programmable DC Source) was turned off. Probably no gate grounding since power shortage.

Todo

write about power shortage.

Histogram of empty cross (m491)

Fig. 37 m491: Histogram of empty cross (gradiometry) at different external fields (subtracted mean).

90deg Repeating selected measurements

Date

Aug. 2020

Note

Changing back to 90deg again to try and repeat some selected signal analyzer measurements (from SR785) with SR830

Changing Angle to 90deg

Important

• Temp: 15K

• \(V_{in}\) = 2.5 V (6-8)

• \(V_H\) = 0.75 μ V (Target: 0 V) (7-14)

• \(V_y\) = 9.7 μ V (Target: 0 V) high phase

Repeat selected signal analyzer measurements with SR830

Repeating	m351-354
Focus	sweeprates

Sweeping Field (different sweeprates)

from -25 mT to 25 mT with negative saturation (at -.9 T)

Nr	Struct	Voltage	Frequency	Temp	Rate	Sweep rate	Limit	timeconstant
494	Empty	5	17	15	8	200/150/100/50	.025	.003
495	Empty	5	17	15	8	20/15/10/5	.025	.003
496	Empty	5	17	15	8	2/1.5/1	.025	.003

Error

m496: Error when measuring Sweeprate SR=0.5 mT/min. (sweep did not start, measurement contains static field voltages).

Changing Angle again to 90deg

Before Changing Angle

Measuring at +1 T external field and adjusting angle.

Note

Field parallel empty Cross (\(V_{in}\) = 2.5 V) before changing

\(I_1\) = (6-8)

\(V_H\) = (7-14)

Tip

\(V_H\) = 88.9 μ V (\(V_y\) = 7.55 μ V,

θ = -4.8deg)

\(I_1\) = (5-10): \(V_H\) = (7-14)

Tip

\(V_H\) = 83.9 μ V ( \(V_y\) = 3.1 μ V,

θ = -2.15deg)

After Changing Angle

5-10

Note

setting 5-10 to 0

\(I_1\) = (5-10)

\(V_H\) = (7-14)

• \(V_H\) = 0.19 μ V

Danger

\(V_y\) = -5.37 μ V

θ = -88deg

6-8

Note

checking 6-8 if contacts are fine.

Expected: voltage is still to 0

\(I_1\) = (6-8)

\(V_H\) = (7-14)

• \(V_H\) = 4.75 μ V

Phase

\(V_y\) = -9.75 μ V

θ = -64deg

Hint

Measuring HLoop at 90deg for Plusses (1-13) parallel.

Repeating m351-354

Sweeping Field (different sweeprates)

from -25 mT to 25 mT (negative saturation at -.9 T)

Nr	Struct	Voltage	Frequency	Temp	Rate	Sweep rate [mT/min]	Limit	timeconstant
497	Plusses	5	17	15	8	20/15/10/5/2.5/1	.025	.003
500	Plusses	5	113	15	8	20/15/10/5/2.5/1	.025	.003
501	Plusses	5	113	15	8	2/1.5/1/0	.025	.003
502	Plusses	5	113	15	8	2/1.5/1/	.025	.03
507	Plusses	5	17	15	8	2/1.5/1/0	.025	.1

Note

• The sweeping of the field results in temperature instability: the temperature varies around ± 3 mK (at a sweeprate of 100 mT/min).

• m500/501 need up to 500min during sweep … resetting buffer after 16000 datapoints (see AGM/EVE#32).

• measurements > 501 Sweeprates below 1 mT/min did not work (magnet did not sweep -> static field).

• Starting with m500 the capacitor C21 was reset to setting 10 to reproduce the signal analyzer measurements where this setting was used.

Repeating m378-382 (different voltages)

from -100 mT to 100 mT with negative saturation (using 5.9 mT/min to measure for 35 min.)

Nr	Struct	Voltage	Frequency	Temp	Rate	Sweep rate [mT/min]	Limit	timeconstant
498	Plusses	5/4.5/../0.5	17	15	8	5.9	.1	.003
499	Plusses	5/4.5/../0.5	113	15	8	5.9	.1	.003
506	Plusses	5/4.5/../0.5	17	15	8	5	.1	.1
508	Plusses	5/4.5/../0.5	17	15	8	5	.1	.1

Note

• m506 did not always saturate at -900mT (but sensitivity is always 100|mu|V (5V -> .5V))

• instead swept -900mT -> -100mT -> +100mT -> -100mT -> +100mt (see Test_measurements/m506.90_Temp_during_meas.dat)

• m508 repeats m506 but adjusts the sensitivity from 100|mu|V (5V -> 2.5V) -> 20|mu|V (2V -> 0.5V).

Repeating m362-366

Important

changing different field ranges

with negative saturation (at -.9 T)

Nr	Struct	Voltage	Frequency	Temp	Rate	Sweep rate [mT/min]	Limit	timeconstant
503	Plusses	5	113	15	8	2	.15/.125/.1/.075/.05	.03
504	Plusses	5	113	15	8	2	.15/.125/.1/.075/.05	.003
505	Plusses	5	113	15	8	2	.15/.125/.1/.075/.05	.1

Note

m504/505 has been interupted during the measurement and continued using m504.2_routine.dat.