Design, Fabrication, and Use of Scientific Apparatus

204 Pages·2016·11.71 MB·English

Physics 240
Design, Fabrication,
and Use of Scientific
Apparatus
Department of Physics and Astronomy
Brigham Young University
Provo, Utah 84602
Version: January 19, 2018
2
This page intentionally left blank as with all other content free even-numbered pages
at the end of a chapter. Except that this one isn’t actually blank, as you can see.
There should probably be some copyright and publisher information here. Therefore:
© 2018, Brigham Young University, Department of Physics and Astronomy, Provo,
Utah.
Contents
Introduction xi
0.1 Course Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . xi
0.2 Course Learning Outcomes . . . . . . . . . . . . . . . . . . . . . . . . xi
0.3 About the Course Packet . . . . . . . . . . . . . . . . . . . . . . . . . xii
1 The Machining Lab 1
1.1 Expected Learning Outcomes . . . . . . . . . . . . . . . . . . . . . . 1
1.2 Grading . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
1.3 Introduction to the machine shop . . . . . . . . . . . . . . . . . . . . 1
1.4 Machining lab regulations and safety . . . . . . . . . . . . . . . . . . 2
1.4.1 The basic rules . . . . . . . . . . . . . . . . . . . . . . . . . . 2
1.4.2 General safety guidelines . . . . . . . . . . . . . . . . . . . . . 4
1.4.3 Lathe operation safety guidelines . . . . . . . . . . . . . . . . 5
1.4.4 Milling machine operation safety guidelines . . . . . . . . . . . 6
1.4.5 Drill press operation safety guidelines . . . . . . . . . . . . . . 7
1.4.6 Cut-off band saw operation safety guidelines . . . . . . . . . . 7
1.5 SolidWorks project drawings and job sheets . . . . . . . . . . . . . . 9
1.6 SpaceClaim project drawings and job sheets . . . . . . . . . . . . . . 17
i
ii
2 Computer-Aided Design 25
2.1 Expected Learning Outcomes . . . . . . . . . . . . . . . . . . . . . . 25
2.2 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
2.3 Grading . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
2.4 SolidWorks CAD exercises . . . . . . . . . . . . . . . . . . . . . . . . 26
2.4.1 Some strong hints for SolidWorks . . . . . . . . . . . . . . . . 26
2.5 SpaceClaim CAD exercises . . . . . . . . . . . . . . . . . . . . . . . . 27
2.5.1 The SpaceClaim tutorials . . . . . . . . . . . . . . . . . . . . 28
3 LabVIEW Programming 29
3.1 Expected Learning Outcomes . . . . . . . . . . . . . . . . . . . . . . 29
3.2 Grading . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
3.3 Introduction to LabVIEW . . . . . . . . . . . . . . . . . . . . . . . . 29
3.3.1 Execution sequencing . . . . . . . . . . . . . . . . . . . . . . . 30
3.3.2 Some LabVIEW resources . . . . . . . . . . . . . . . . . . . . 31
3.4 LabVIEW Basics Course . . . . . . . . . . . . . . . . . . . . . . . . . 31
3.5 LabVIEW exercises . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
3.5.1 Exercise specific instructions . . . . . . . . . . . . . . . . . . . 32
4 Thermal Measurements Lab: Heating and Cooling of the Cryostat
Assembly 39
4.1 Expected Learning Outcomes . . . . . . . . . . . . . . . . . . . . . . 39
4.2 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
4.3 Equipment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40
4.4 Grading . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
4.5 Summary of steps to carry out the measurements . . . . . . . . . . . 41
4.6 Lab notebooks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42
iii
4.7 Your technical report on the experiment . . . . . . . . . . . . . . . . 42
4.8 Building Models in experimental physics . . . . . . . . . . . . . . . . 43
4.8.1 Modeling the measurement tools . . . . . . . . . . . . . . . . 44
4.8.2 Modeling the physical apparatus . . . . . . . . . . . . . . . . 44
4.9 Constructing a heater coil on your aluminum heater block . . . . . . 45
4.10 Measuring the temperature of the heater block . . . . . . . . . . . . . 45
4.11 Data collection using LabVIEW . . . . . . . . . . . . . . . . . . . . . 46
4.11.1 Diode calibration: analysis questions and requests . . . . . . . 49
4.12 Measuring the thermal parameters of the cryostat assembly . . . . . . 50
4.12.1 Determiningtheheatingandcoolingrateofthecryostatassembly 50
4.12.2 A model for analyzing the heating/cooling data . . . . . . . . 51
4.12.3 Fitting a theoretical model to your experimental results . . . . 52
4.12.4 Thermal parameters: analysis questions and requests . . . . . 52
5 Controlling Temperature and the Controller Contest 55
5.1 Expected Learning Outcomes . . . . . . . . . . . . . . . . . . . . . . 55
5.2 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55
5.3 Temperature controller contest . . . . . . . . . . . . . . . . . . . . . . 55
5.4 Equipment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56
5.5 Grading . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57
5.6 Selecting the proper control variable . . . . . . . . . . . . . . . . . . 57
5.7 Controlling the Kepco power supply . . . . . . . . . . . . . . . . . . . 58
5.8 Controlling the heater with a simple model . . . . . . . . . . . . . . . 59
5.9 PID controller model . . . . . . . . . . . . . . . . . . . . . . . . . . . 60
5.9.1 Tuning a PID controller . . . . . . . . . . . . . . . . . . . . . 62
5.10 Some useful LabVIEW functions . . . . . . . . . . . . . . . . . . . . 62
iv
5.11 Integrals and derivatives of experimental data . . . . . . . . . . . . . 63
5.12 Making your controller work . . . . . . . . . . . . . . . . . . . . . . . 63
6 Resistivity vs. Temperature of a Superconductor 65
6.1 Expected Learning Outcomes . . . . . . . . . . . . . . . . . . . . . . 65
6.2 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65
6.3 Equipment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 66
6.4 Grading . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67
6.5 Literature search . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67
6.5.1 How to read a journal article . . . . . . . . . . . . . . . . . . . 68
6.6 Preparation for the measurement . . . . . . . . . . . . . . . . . . . . 68
6.6.1 Calibrating the diode for temperature measurement . . . . . . 69
6.6.2 A constant current supply for measuring the resistance . . . . 70
6.7 Acquiring the data . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72
6.8 Analysis to prepare to write your formal report . . . . . . . . . . . . 73
7 Superconductor Formal Report 75
7.1 Grading . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75
7.2 Annotated bibliography instructions . . . . . . . . . . . . . . . . . . . 76
7.3 The formal report . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 77
7.3.1 Preparing to write . . . . . . . . . . . . . . . . . . . . . . . . 77
7.3.2 Medium and length . . . . . . . . . . . . . . . . . . . . . . . . 78
7.3.3 Audience . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 78
7.3.4 Content and organization . . . . . . . . . . . . . . . . . . . . 79
7.3.5 Report dos and don’ts . . . . . . . . . . . . . . . . . . . . . . 80
v
8 Ethics Discussion 83
8.1 Expected Learning Outcomes . . . . . . . . . . . . . . . . . . . . . . 83
8.2 Grading . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 83
8.3 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 84
8.4 Ethics resources . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 84
9 Group Projects and Presentations 87
9.1 Expected Learning Outcomes . . . . . . . . . . . . . . . . . . . . . . 87
9.2 Project guidelines . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 87
9.3 Oral presentation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 88
9.3.1 Scheduled presentation time . . . . . . . . . . . . . . . . . . . 88
9.3.2 Presentation audience . . . . . . . . . . . . . . . . . . . . . . 88
9.3.3 Presentation guidelines . . . . . . . . . . . . . . . . . . . . . . 88
9.3.4 Grading of presentations/projects . . . . . . . . . . . . . . . . 89
9.3.5 Suggested reading . . . . . . . . . . . . . . . . . . . . . . . . . 90
A Machine Tool Speeds and Feeds 91
B Considerations for Analog Input and Output 95
B.1 Input Connections . . . . . . . . . . . . . . . . . . . . . . . . . . . . 95
B.1.1 Grounds . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 96
B.1.2 Ground loops . . . . . . . . . . . . . . . . . . . . . . . . . . . 97
B.2 Signal conditioning . . . . . . . . . . . . . . . . . . . . . . . . . . . . 98
B.3 Device specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . 98
B.3.1 Overvoltage protection . . . . . . . . . . . . . . . . . . . . . . 98
B.3.2 Maximum working voltage . . . . . . . . . . . . . . . . . . . . 98
B.3.3 Device resolution . . . . . . . . . . . . . . . . . . . . . . . . . 99
vi
B.3.4 Input impedance . . . . . . . . . . . . . . . . . . . . . . . . . 99
B.3.5 Sample rate and aliasing . . . . . . . . . . . . . . . . . . . . . 99
B.3.6 Settling time . . . . . . . . . . . . . . . . . . . . . . . . . . . 101
B.4 Analog output . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 101
B.5 Input offset voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . 102
B.6 Dithering . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 102
B.7 Electrical noise . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 103
C Uncertainty, Errors, and Noise in Experimental Measurements 107
C.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 107
C.2 Some sources of error and uncertainty in measurements . . . . . . . . 108
C.2.1 Limitations in measurement precision . . . . . . . . . . . . . . 108
C.2.2 Limitations in measurement accuracy . . . . . . . . . . . . . . 109
C.2.3 Uncertainty due to electrical noise . . . . . . . . . . . . . . . . 109
C.3 A summary of relevant statistics . . . . . . . . . . . . . . . . . . . . . 111
C.3.1 Binomial distribution . . . . . . . . . . . . . . . . . . . . . . . 113
C.3.2 Poisson distribution . . . . . . . . . . . . . . . . . . . . . . . . 114
C.3.3 The uniform distribution . . . . . . . . . . . . . . . . . . . . . 114
C.3.4 The normal or Gaussian distribution . . . . . . . . . . . . . . 115
C.4 Propagating errors . . . . . . . . . . . . . . . . . . . . . . . . . . . . 116
C.5 Dealing with noise in measurements . . . . . . . . . . . . . . . . . . . 117
C.5.1 Signal averaging to “remove” noise . . . . . . . . . . . . . . . 117
C.5.2 Filtering to reduce noise . . . . . . . . . . . . . . . . . . . . . 119
C.6 Systematic errors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 119
vii
D Statistics Review for Experimental Measurements 123
D.1 Probability distributions . . . . . . . . . . . . . . . . . . . . . . . . . 123
D.1.1 Binomial distribution . . . . . . . . . . . . . . . . . . . . . . . 125
D.1.2 Poisson distribution . . . . . . . . . . . . . . . . . . . . . . . . 127
D.1.3 The uniform distribution . . . . . . . . . . . . . . . . . . . . . 129
D.1.4 The normal or Gaussian distribution . . . . . . . . . . . . . . 130
D.2 Comparison of distributions . . . . . . . . . . . . . . . . . . . . . . . 132
D.3 Propagating errors . . . . . . . . . . . . . . . . . . . . . . . . . . . . 133
D.3.1 Offset voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . 135
D.3.2 Signal averaging . . . . . . . . . . . . . . . . . . . . . . . . . . 135
E Your Lab Notebook 137
E.1 What to include in your lab notebook . . . . . . . . . . . . . . . . . . 138
E.2 Notebook grading . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 140
F Heater Construction 141
G Four-Lead Measurement of Resistance 143
G.1 Four-lead measurement technique . . . . . . . . . . . . . . . . . . . . 143
H Temperature Transducers 145
H.1 Thermocouple . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 145
H.2 Thermistor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 146
H.3 RTD, resistance temperature detector . . . . . . . . . . . . . . . . . . 146
H.4 Silicon diode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 146
viii
I Measuring Temperature with a Silicon Diode 149
I.1 Analysis of the thermal dependence in the diode equation . . . . . . . 149
I.2 Checking the validity of the linear assumption . . . . . . . . . . . . . 150
I.3 Estimating the error in the measured temperature . . . . . . . . . . . 151
I.3.1 Calibration with V=mT+b . . . . . . . . . . . . . . . . . . . 152
I.3.2 Calibration with T=m’V+b’ . . . . . . . . . . . . . . . . . . . 153
I.4 Estimating the effect of varying diode current . . . . . . . . . . . . . 154
J A Constant-current Source 157
J.1 Optional voltage monitor . . . . . . . . . . . . . . . . . . . . . . . . . 160
J.2 Getting your circuit to work . . . . . . . . . . . . . . . . . . . . . . . 160
K The Art of Debugging 161
K.1 Debugging electronics . . . . . . . . . . . . . . . . . . . . . . . . . . . 162
K.2 Debugging software . . . . . . . . . . . . . . . . . . . . . . . . . . . . 163
K.3 Debugging an experiment . . . . . . . . . . . . . . . . . . . . . . . . 164
K.4 A few things to remember . . . . . . . . . . . . . . . . . . . . . . . . 165
L Calibrating a Silicon Diode for Temperature Measurement 167
L.1 Diode calibration: analysis questions and requests . . . . . . . . . . . 168
M Fitting data with Logger Pro 171
N Fitting data with Mathematica 175
O Fitting data with Matlab 179
P Fitting data with Excel 185