Reliability in Scientific Research: Improving the Dependability of Measurements, Calculations, Equipment, and Software

Cover......Page 1
Half-title......Page 3
Title......Page 5
Copyright......Page 6
Dedication......Page 7
Contents......Page 9
Preface......Page 21
Abbreviations......Page 23
1.2 Central points......Page 25
1.3.1.2 Finding out what is known......Page 29
1.3.1.3 A digression on sources of information......Page 30
1.3.1.5 Paying attention to detail......Page 31
1.3.2.1 Frequency of problems caused by human error......Page 32
1.3.2.2 Dominant types of human error – related problems......Page 33
1.3.2.3 Dominant causes of human error – related problems......Page 34
Frustration......Page 35
1.3.3.2 Preparation and planning......Page 36
1.3.3.3 Automation......Page 37
1.3.3.6 Omissions caused by strong habits......Page 38
Lighting......Page 39
Air conditioning......Page 40
1.3.3.8 Design of systems and tasks......Page 41
1.3.3.9 Procedures and documentation......Page 42
1.3.3.10 Labeling......Page 43
1.3.4.1 Communication......Page 44
1.3.4.3 The value of division of labor......Page 45
1.3.4.5 Problems with communal equipment......Page 46
1.3.4.7 Presence of non research-related people in the laboratory......Page 47
1.4.1 Record-keeping......Page 48
1.4.3 Troubleshooting equipment and software......Page 49
1.5 Reliability of information......Page 52
1.3.2 Some data on human error......Page 55
1.3.4 Interpersonal and organizational issues......Page 56
1.4.3 Troubleshooting equipment and software......Page 57
References......Page 58
2.2.3 Errors in technique......Page 60
2.2.5 Errors in published tables......Page 62
2.2.6 Problems arising from the use of computer algebra systems......Page 63
2.2.7 Errors in numerical calculations......Page 64
2.3.2 Use of diagrams......Page 66
2.3.4 Keeping things simple......Page 67
2.3.7 Outsourcing the problem......Page 68
2.3.10 Practices for manual calculations......Page 69
2.4.1 General remarks......Page 70
2.4.3 Predicting simple features of the solution from those of the problem......Page 71
2.4.5 Further checks involving internal consistency......Page 72
2.4.8 Check calculations......Page 73
2.4.9 Comparing the results of the calculation against known results......Page 75
2.4.10 Detecting errors in computer algebra calculations......Page 76
2.3 Strategies for avoiding errors......Page 77
2.4 Testing for errors......Page 78
References......Page 79
3.2 Stress derating......Page 82
3.3.2 Some causes and characteristics......Page 84
3.3.3 Preventing and solving intermittent problems......Page 86
3.4.1.2 Reduction and regulation of room temperatures......Page 87
3.4.1.3 Measures for preventing the overheating of equipment......Page 88
3.4.2.1 Definitions......Page 89
3.4.2.2 Harmful effects of moisture......Page 90
3.4.2.4 Avoiding moisture problems......Page 91
3.5.1 Introduction......Page 92
3.5.2 Large-amplitude vibration issues......Page 93
3.5.3.1 Measurement difficulties and sources of vibration......Page 95
Selecting a suitable site......Page 97
Isolating sensitive apparatus from floor vibrations......Page 100
Isolating vibrations in pumping lines, electrical cables, and pipes......Page 102
Controlling vibrations at their source......Page 104
Rigidity and stability of optical mounts......Page 105
Other measures......Page 106
Brownouts and sags......Page 107
Swells and transients......Page 108
3.6.2 Investigating power disturbances......Page 109
3.6.3.2 Reduction of RF electrical noise......Page 110
3.6.3.4 Uninterruptible power supplies......Page 111
Double-conversion types......Page 112
Selection and use of UPSs......Page 113
3.6.3.5 Standby generators......Page 114
3.7.2 Conditions encountered during transport......Page 115
3.7.3 Packaging for transport......Page 117
3.7.5 Insurance......Page 119
3.8.2 Oil and water in compressed air supplies......Page 120
3.8.3 Silicones......Page 121
3.9 Galvanic and electrolytic corrosion......Page 123
3.10 Enhanced forms of materials degradation related to corrosion......Page 124
3.11.2 Prevalence and examples of fatigue......Page 125
3.11.3 Characteristics and causes......Page 126
3.12 Damage caused by ultrasound......Page 128
3.2 Stress derating......Page 129
3.4.2 Moisture......Page 130
3.5.3 Interference with measurements......Page 131
3.6 Electricity supply problems......Page 132
3.7 Damage and deterioration caused by transport......Page 133
3.9 Galvanic and electrolytic corrosion......Page 134
References......Page 135
4.2 Using established technology and designs......Page 140
4.4 Understanding the basics of a technology......Page 141
4.5 Price and quality......Page 142
4.6.2 Place of origin of a product......Page 143
4.6.6 True meaning of specifications......Page 144
4.6.8 Testing items prior to purchase......Page 145
4.7.3 Reliability incentive contracts......Page 146
4.7.4 Actions to take before delivery......Page 147
4.8 Use of manuals and technical support......Page 148
Summary of some important points......Page 149
References......Page 150
5.2 Commercial vs. self-made items......Page 151
5.3 Time issues......Page 152
5.5 Making apparatus fail-safe......Page 153
5.6 The use of modularity in apparatus design......Page 154
5.7 Virtual instruments......Page 155
5.8 Planning ahead......Page 156
5.9 Running the apparatus on paper before beginning construction......Page 157
5.11 Designing apparatus for diagnosis and maintainability......Page 158
5.14 Ergonomics and aesthetics......Page 159
Summary of some important points......Page 160
References......Page 161
6.1 Introduction......Page 162
6.2 Classifications of leak-related phenomena......Page 163
6.3 Common locations and circumstances of leaks......Page 164
6.4 Importance of modular construction......Page 165
6.5.1 General points......Page 166
6.5.2 Leak testing raw materials......Page 167
6.5.3 Stainless steel......Page 168
6.5.7 Copper......Page 170
6.6.1 Cleaning agents......Page 171
6.6.2 Vacuum-pump fluids and substances......Page 172
6.6.4 Other type of contamination......Page 173
6.7.1 Worker qualifications and vacuum-joint leak requirements......Page 174
6.7.2.2 Semi-permanent joints......Page 175
6.7.2.4 Improving bonding characteristics with surface coatings......Page 176
6.7.2.7 Joining of bellows......Page 177
6.7.4.1 Arc welding......Page 178
6.7.4.2 Welding of specific materials......Page 179
6.7.4.3 Electron-beam welding......Page 180
6.7.5 Brazing......Page 181
6.7.6.1 Introduction......Page 182
Purity requirements......Page 183
Solder joints in low-temperature applications......Page 184
6.7.6.5 Design of the solder joint, and the soldering process......Page 186
6.7.6.6 Soldering difficult materials......Page 187
6.8 Use of guard vacuums to avoid chronic leak problems......Page 188
6.9.1 Items involving fragile materials subject to thermal and mechanical stresses......Page 189
6.9.2 Water-cooled components......Page 190
6.9.3 Metal bellows......Page 191
6.10.1.1 Introduction......Page 194
Introduction......Page 196
Helium leak-testing techniques......Page 197
6.10.1.3 Some potential problems during leak detection......Page 198
Introduction......Page 199
General methods......Page 200
Superleaks......Page 201
Locating large leaks at very large distances......Page 202
6.11 Leak repairs......Page 203
6.5 Selection of materials for use in vacuum......Page 205
6.6 Some insidious sources of contamination and outgassing......Page 206
6.7.4 Welding......Page 207
6.7.6 Soldering......Page 208
6.9 Some particularly trouble-prone components......Page 209
6.11 Leak repairs......Page 210
References......Page 211
7.2.1.1 General issues concerning mechanical primary pumps......Page 214
Prevention of contamination from pump oil......Page 215
Leaks......Page 217
7.2.1.3 Oil-free scroll and diaphragm pumps, and other “dry” positive-displacement primary pumps......Page 218
Introduction......Page 219
Vacuum-system contamination......Page 220
Automatic protection devices......Page 221
Introduction......Page 222
Magnetic-bearing turbopumps......Page 223
Consequences of improper venting......Page 224
7.2.2.3 Cryopumps......Page 225
Advantages......Page 226
Limitations......Page 227
Deterioration and failure modes......Page 228
Sublimation pumps......Page 229
Non-evaporable getter pumps......Page 230
7.3.1 General points......Page 231
7.3.3 Capacitance manometers......Page 232
7.3.5 Bayard–Alpert ionization gauges......Page 233
7.4.1 Human error and manual valve operations......Page 234
7.4.2 Selection of bakeout temperatures for UHV systems......Page 235
7.4.3 Cooling of electronics in a vacuum......Page 236
7.2.1 Primary pumps......Page 237
7.2.2 High-vacuum pumps......Page 238
7.4 Other issues......Page 239
References......Page 240
8.2.1 Overview of conditions that reduce reliability......Page 242
Advantages and disadvantages......Page 243
Methods for operating flexural mechanisms......Page 245
8.2.2.2 Direct versus indirect drive mechanisms......Page 246
8.2.3 Precision positioning devices in optical systems......Page 247
8.2.5.1 Plain bearings......Page 248
8.2.5.2 Rolling-element bearings......Page 249
8.2.7.1 Introduction......Page 251
8.2.7.2 Selection of materials for sliding contact......Page 252
8.2.7.4 Liquid lubricants for harsh conditions......Page 253
8.2.7.5 Dry lubricants......Page 255
Damage to sealing surfaces and seals......Page 257
Leaks due to contaminants on seals and sealing surfaces......Page 258
Tightening of threaded fasteners on flanges......Page 259
Introduction......Page 260
Materials properties and selection......Page 261
Installation and removal......Page 262
8.2.8.3 Flat metal gasket seals of the “ConFlat®” or “CF” design......Page 263
8.2.8.4 Metal-gasket face-sealed fittings for small-diameter tubing......Page 264
8.2.8.5 Helicoflex® metal O-ring seals......Page 265
8.2.8.6 Indium seals for cryogenic applications......Page 266
8.2.8.8 Weld lip connections......Page 269
8.2.9.1 Devices employing sliding seals......Page 270
8.2.9.3 Magnetic fluid seals......Page 271
8.2.9.4 Magnetic drives......Page 272
8.2.9.5 Use of electric motors in the sealed environment......Page 273
8.2.10.1 Introduction......Page 274
Pressure relief valves......Page 276
Rupture discs......Page 278
8.2.10.4 Metering valves......Page 279
8.2.10.6 Gate, poppet, and load lock vacuum valves......Page 281
8.2.10.7 Solenoid- and pneumatic-valves......Page 282
8.2.10.8 Advantages of ball valves – particularly for water......Page 283
8.3.2 Selection of materials......Page 284
8.3.3 Construction issues......Page 285
8.3.5 Filter issues......Page 286
8.4.1 Introduction......Page 287
8.4.2.1 Introduction......Page 289
8.4.2.3 Termination of hoses......Page 290
8.4.2.4 Automatic detection of water leaks......Page 291
8.4.3.2 Removal and control of impurities......Page 292
8.4.5 Condensation......Page 294
Further reading......Page 295
8.2.3 Precision positioning devices in optical systems......Page 296
8.2.7 Lubrication and wear under extreme conditions......Page 297
8.2.8.2 O-rings......Page 298
8.2.8.7 Conical taper joints for cryogenic applications......Page 299
8.2.10.1 Introduction......Page 300
8.2.10.6 Gate, poppet, and load-lock vacuum valves......Page 301
8.3 Systems for handling liquids and gases......Page 302
8.4.3 Water purity requirements......Page 303
References......Page 304
9.1 Introduction......Page 309
9.2 Difficulties caused by the delicate nature of cryogenic apparatus......Page 310
9.3 Difficulties caused by moisture......Page 312
9.4 Liquid-helium transfer problems......Page 313
9.5 Large pressure buildups within sealed spaces......Page 314
9.6 Blockages of cryogenic liquid and gas lines......Page 315
9.8 Cryogen-free low-temperature systems......Page 317
9.9 Heat leaks......Page 318
9.10.3.1 Thermal conductance vs. contact force......Page 320
9.10.3.3 Indium foil as a gap filler......Page 321
9.10.3.4 Optimizing heat transport through direct metal-to-metal contacts......Page 322
9.11 1 K pots......Page 324
9.12.3 Measurement errors due to RF heating and interference......Page 325
9.12.4 Causes of thermometer calibration shifts......Page 326
9.13 Problems arising from the use of superconducting magnets......Page 327
9.3 Difficulties caused by moisture......Page 329
9.7 Other problems caused by the presence of air in cryostats......Page 330
9.12 Thermometry......Page 331
References......Page 332
10.2 Temperature variations in the optical path......Page 334
10.3 Temperature changes in optical elements and support structures......Page 336
10.4 Materials stability......Page 338
10.5 Etalon fringes......Page 339
10.6.1 Introduction......Page 342
10.6.2.1 High-power light systems......Page 345
10.6.2.3 Diffraction gratings......Page 346
10.6.3 Measures for protecting optics......Page 347
10.6.4 Inspection......Page 350
10.6.5.1 Introduction......Page 351
10.6.5.2 Some general cleaning procedures......Page 352
10.6.5.3 Some cleaning agents to be avoided in the cleaning of optics......Page 354
10.6.5.5 Vapor degreasing......Page 355
10.6.5.8 Cleaning by using reactive gases......Page 356
10.7.1 Problems with IR and UV materials caused by moisture, and thermal and mechanical shocks......Page 357
10.7.3 Corrosion and mold growth on optical surfaces......Page 358
10.7.4.2 Sapphire......Page 359
10.7.4.5 Fused silica or silicon carbide diffraction gratings......Page 360
10.8.3 Insensitivity to crosstalk and EMI, and sensitivity to environmental disturbances......Page 361
10.9.1.1 Introduction......Page 362
10.9.1.4 Microphonics......Page 363
10.9.1.5 Active compensation methods for reducing noise and drift......Page 364
10.9.2.1 Diode lasers......Page 365
10.9.2.3 Other gas lasers......Page 366
10.9.3 Some incoherent light sources......Page 367
10.11 Photomultipliers and other light detectors......Page 368
10.2 Temperature variations in the optical path......Page 369
10.5 Etalon fringes......Page 370
10.6 Contamination of optical components......Page 371
10.8 Fiber optics......Page 372
10.9 Light sources......Page 373
References......Page 374
Importance of grounding arrangements......Page 377
The nature of the problem......Page 378
Unexpected behavior......Page 380
Planning ground systems and the use of ground maps......Page 381
Single-point grounding......Page 383
The provision of floating power......Page 384
Opening ground loops in the signal path......Page 386
Some methods of reducing the effects of unavoidable ground loops......Page 391
11.2.1.3 Detecting ground loops......Page 392
11.2.2.1 Introduction......Page 394
Precautionary measures......Page 396
Shields......Page 397
Filters......Page 398
Radio-frequency grounding......Page 400
Shielded rooms......Page 401
11.2.2.4 Detecting and locating RF noise in the environment......Page 402
11.2.3.1 Affected items......Page 403
11.2.3.3 Prevention of interference......Page 404
11.2.4 Some EMI issues involving cables, including crosstalk between cables......Page 405
11.3.1 The phenomena and their effects......Page 406
11.3.2 Conditions likely to result in discharges......Page 407
11.3.3 Measures for preventing discharges......Page 408
11.3.4 Detection of corona and tracking......Page 410
11.4.1 The difficulties......Page 411
11.4.2 Some solutions......Page 412
11.5.1 Origins, character, and effects of ESD......Page 414
11.5.2 Preventing ESD problems......Page 417
11.6 Protecting electronics from excessive voltages......Page 418
11.7 Power electronics......Page 419
11.8.1.2 Switch selection for low and high current and voltage levels......Page 421
11.8.1.3 Switching large inductive loads......Page 422
11.8.1.5 Alternatives to mechanical switches, relays and thermostats for improved reliability......Page 423
11.8.3 Fans......Page 424
11.8.5 Batteries......Page 425
Further reading......Page 427
11.2.1 Grounding and ground loops......Page 428
11.2.2 Radio-frequency interference......Page 429
11.4 High-impedance systems......Page 430
11.6 Protecting electronics from excessive voltages......Page 431
11.8.4 Aluminum electrolytic capacitors......Page 432
References......Page 433
12.1 Introduction......Page 437
12.2.1.1 Modes of failure......Page 438
Weakness of solder and the need for mechanical support......Page 439
Selection of solder......Page 440
12.2.1.4 Electrostatic discharge (ESD) issues......Page 442
Dissolution of thin conductors (especially gold) by solder......Page 443
Gold embrittlement......Page 444
Use of solder in high-temperature environments or high-current circuits......Page 445
12.2.2.1 Crimp connections......Page 446
12.2.2.2 Welding and brazing......Page 447
12.2.2.3 Use of mechanical fasteners in high-current connections......Page 448
12.2.3.1 Ultrasonic soldering......Page 449
12.2.3.2 Friction-soldering methods......Page 450
12.2.3.3 Solders for joining difficult materials......Page 451
12.2.3.8 Silver epoxy......Page 452
12.2.4 Ground contacts......Page 453
12.2.5 Minimization of thermoelectric EMFs in low-level d.c. circuits......Page 454
12.3.2 Failure modes......Page 455
12.3.3.1 Human error......Page 457
12.3.3.2 Damage and degradation during normal operation and use......Page 458
12.3.3.3 Corrosion......Page 459
12.3.4.1 General points......Page 461
12.3.4.2 Contact materials......Page 466
12.3.4.3 Connector derating in the presence of large currents or voltages......Page 467
12.3.4.5 Provision of a ground pin in multi-pin connectors......Page 468
12.3.5.2 High-voltage connectors......Page 469
12.3.5.3 High-current connectors......Page 470
12.3.5.4 Mains-power plugs and receptacles......Page 471
12.3.6.2 Reducing contact wear and corrosion......Page 472
12.3.6.3 Minimizing crosstalk problems in multi-pin connectors......Page 473
12.3.6.5 Inspection and cleaning......Page 474
12.4.1 Modes of failure......Page 475
12.4.2.1 Vulnerable cable types......Page 476
12.4.2.3 Cable deterioration and ageing......Page 477
12.4.3.1 Provenance......Page 478
12.4.3.3 Choosing cables for use under conditions of flexure and vibration......Page 479
12.4.4.1 Grounding of cable shields......Page 480
12.4.4.2 Choice of cable-shield coverage......Page 481
12.4.4.4 Attachment of shielded cables to their connectors (“pigtail” problems)......Page 483
12.4.4.5 Rapid fixes for cables with inadequate shields......Page 484
12.4.4.6 Use of twisted-wire pairs in the presence of low-frequency interfering fields......Page 485
12.4.5.1 GP-IB cable assemblies......Page 486
12.4.6.1 Installation......Page 487
12.4.6.4 Cable inspection and replacement......Page 489
Selection and removal of enamel19......Page 490
Wiring for cryogenic systems......Page 492
Soldering small enameled wires......Page 494
12.5.2.1 Resistance......Page 495
12.5.3 High-resistance and open- and short-circuit intermittent faults......Page 496
12.5.4 Use of infrared thermometers on high-current contacts......Page 497
12.5.6 Fault detection and location in cables......Page 498
12.2.1 Soldering......Page 499
12.2.4 Ground contacts......Page 500
12.3.3 Causes of connector failure......Page 501
12.3.5 Some particularly troublesome connector types......Page 502
12.4.2 Cable damage and degradation......Page 503
12.4.5 Some comments concerning GP-IB and ribbon cables......Page 504
12.4.7 Wire issues – including cryostat wiring......Page 505
References......Page 506
13.2.1 Selection......Page 511
13.2.2 Some common causes of system crashes and other problems......Page 513
13.3 Industrial PCs and programmable logic controllers......Page 514
13.4.1.1 Risks and causes of hard-drive failure......Page 515
13.4.1.2 Use of redundant disc (RAID) systems......Page 516
13.4.1.4 Recovery of data from failed hard drives......Page 517
13.4.2 Power supplies......Page 518
13.4.3 Mains-power quality and the use of power-conditioning devices......Page 519
13.4.5.2 Data errors on RS-232 links......Page 520
13.4.5.4 Advantages of GP-IB and USB......Page 521
13.4.5.7 References on RS-232, RS-485, and GP-IB......Page 522
13.5.2 Some backup techniques and strategies......Page 523
13.6 Long-term storage of information and the stability of recording media......Page 524
13.7.2 Viruses and their effects......Page 526
13.7.4 Measures for preventing virus attacks......Page 527
13.8.1 Avoiding early releases and beta software......Page 528
13.8.2 Questions for software suppliers......Page 529
13.8.4 Open-source software......Page 530
13.10.2 Graphical languages......Page 531
13.10.3 Some concerns with graphical programming......Page 532
13.11 Precautions for collecting experimental data over extended periods......Page 533
13.12.1 Introduction......Page 534
13.12.2.2 Code requirements......Page 535
Architecture......Page 536
Properties of routines......Page 537
13.12.3.1 Use of pseudocode for detailed design......Page 538
13.12.3.2 Pair programming......Page 540
General points......Page 541
13.12.3.5 Structured programming......Page 542
13.12.3.6 Naming of variables and routines......Page 543
13.12.3.8 Code documentation......Page 544
13.12.3.9 Testing program inputs for errors......Page 545
13.12.3.10 Common programming errors......Page 546
13.12.4.1 Introduction......Page 547
General approach......Page 548
Debugging tools......Page 549
13.13 Using old laboratory software......Page 550
13.2.1 Selection......Page 551
13.4.1 Hard-disc drives......Page 552
13.5 Backing-up information......Page 553
13.8 Reliability of commercial and open-source software......Page 554
13.12.1 Introduction......Page 555
13.12.3 Detailed program design and construction......Page 556
References......Page 557
14.2 Knowing apparatus and software......Page 560
14.3 Calibration and validation of apparatus......Page 561
14.4 Control experiments......Page 562
14.6.1 Introduction......Page 564
14.6.3 Subconscious biases in data analysis......Page 565
14.6.4 Subconscious biases caused by social interactions......Page 566
14.8.1 Introduction......Page 567
14.8.2 The case of polywater......Page 568
14.8.3 Some useful measures......Page 570
14.9.1 Introduction......Page 571
14.9.3 Laboratory visits as a way of acquiring missing expertise......Page 572
14.9.4 A historical example: measuring the Q of sapphire......Page 573
14.10 Low signal-to-noise ratios and statistical signal processing......Page 575
14.11.2 A brief outline and history......Page 576
14.11.3 Origins of the problems......Page 577
14.11.4 Conclusions......Page 581
14.12 Understanding one’s apparatus and bringing it under control: the example of the discovery of superfluidity in He3......Page 582
Further reading......Page 583
14.5 Failure of auxiliary hypotheses as a cause of failure of experiments......Page 584
14.9 Reproducibility of experimental measurements and techniques......Page 585
References......Page 586
Index......Page 588