PH255: Modern Physics LaboratoryPatrick R. LeClairAugust 23, 2012Contents1 PH255 Course Syllabus 11.1 Course Content & Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11.2 Reporting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21.3 Laboratory Safety . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71.4 Grading scale . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 92 Experiments & Schedule 112.1 Shorter experiments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 112.2 Longer experiments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 122.3 Schedule. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 123 The Care & Feeding of Laboratory Notebooks 154 Laboratory Safety 174.1 General rules . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 174.2 High Voltage Safety & Electronic Equipment Considerations . . . . . . . . . . . . . 174.3 General Precautions When Using Lasers . . . . . . . . . . . . . . . . . . . . . . . . 204.4 Radiation Safety . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 204.5 Cryogenics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 224.6 What to do if an Injury Incident Occurs . . . . . . . . . . . . . . . . . . . . . . . . 225 Counting Statistics 255.1 Hypothesis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 255.2 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 255.3 Binomial, Poisson, and Gaussian Statistics . . . . . . . . . . . . . . . . . . . . . . . 265.4 Objective . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 305.5 Preparatory Questions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 305.6 Relevant Reading. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 305.7 Supplies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 305.8 Suggested procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 315.9 Data analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 335.10 Discussion and topics for your report . . . . . . . . . . . . . . . . . . . . . . . . . . 345.11 Format of report . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35iiCONTENTS iiiAppendix 1: A Quick Review of Standard Deviation . . . . . . . . . . . . . . . . . . . . . 35Appendix 2:137Cs Decay and Gamma Emission . . . . . . . . . . . . . . . . . . . . . . . 376 Gamma ray attenuation 396.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 396.2 Objective . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 426.3 Preparatory Questions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 436.4 Supplies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 436.5 Suggested procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 446.6 Data analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 466.7 Format of report . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 476.8 Discussion and topics for your report . . . . . . . . . . . . . . . . . . . . . . . . . . 47Appendix 1: Electromagnetic spectrum . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48Appendix 2: Density of various materials . . . . . . . . . . . . . . . . . . . . . . . . . . . 50Appendix 3: Gamma sources available . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50Appendix 4: Additional data for137Cs and57Co . . . . . . . . . . . . . . . . . . . . . . . 507 Electron Charge to Mass Ratioe/m 537.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 537.2 Objective . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 557.3 Preparatory Questions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 567.4 Supplies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 567.5 Suggested procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 577.6 Data analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 597.7 Format of report . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 607.8 Discussion and topics for your report . . . . . . . . . . . . . . . . . . . . . . . . . . 60Appendix 1: Example Data Table . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 618 The Photoelectric eect 638.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 638.2 Objective . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 668.3 Preparatory Questions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 668.4 Relevant Reading. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 668.5 Supplies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 668.6 Suggested Setup & Alignment procedure. . . . . . . . . . . . . . . . . . . . . . . . 678.7 Experimental Procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 718.8 Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 738.9 Format of report . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73Appendix 1: UV Safety . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73Appendix 2: Visible Spectrum . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 74Appendix 3: Lamp and Filter Reference Data. . . . . . . . . . . . . . . . . . . . . . . . . 74iv CONTENTS9 Observation of Atomic Spectra 779.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 779.2 Objective . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 859.3 Preparatory Questions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 869.4 Relevant Reading. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 869.5 Supplies & Equipment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 869.6 Suggested procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 879.7 Discussion & Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 939.8 Format of report . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 94Appendix 1: Reference Spectral Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 95Appendix 2: USB-650 Red Tide Specications . . . . . . . . . . . . . . . . . . . . . . . . 97Appendix 3: Visible Spectrum . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9710 Speed of Light 9911 Plancks Constant from LEDs 10111.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10111.2 Objective . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10411.3 Preparatory Questions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10411.4 Supplies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10511.5 Suggested procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10511.6 Data analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10911.7 Discussion and topics for your report . . . . . . . . . . . . . . . . . . . . . . . . . . 109Appendix 1: Visible Spectrum . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 110Appendix 2: LED Wavelengths . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11012 Measurement ofe/k 11112.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11112.2 Objective . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11412.3 Preparatory Questions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11512.4 Relevant Reading. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11512.5 Supplies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11512.6 Suggested procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11512.7 Data analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12012.8 Discussion and topics for your report . . . . . . . . . . . . . . . . . . . . . . . . . . 12012.9 Format of report . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 121Appendix 1: Simplied 2N1724 Datasheet . . . . . . . . . . . . . . . . . . . . . . . . . . . 121Appendix 2: Simplied ECG-130 Datasheet . . . . . . . . . . . . . . . . . . . . . . . . . . 12113 Polarization and Diraction of Light 12313.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 123CONTENTS v13.2 Objective . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12713.3 Preparatory Questions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12713.4 Supplies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12813.5 Suggested procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12813.6 Data analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13213.7 Format of report . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13213.8 Discussion and topics for your report . . . . . . . . . . . . . . . . . . . . . . . . . . 13314 Fine Structure in Atomic Spectra 13514.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13514.2 Objective . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14214.3 Supplies & Equipment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14314.4 Suggested procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 143Appendix 1: Reference Spectral Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 144Appendix 2: Angular Momentum Correction to Hydrogen Levels . . . . . . . . . . . . . . 144Appendix 3: Center-of-Mass Correction to the Hydrogen Energies . . . . . . . . . . . . . 14515 Charge Quantization 15115.1 Objective . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15115.2 Relevant Reading. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15115.3 Supplies & Equipment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15115.4 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 151Appendix 1: Viscosity of dry air as a function of temperature. . . . . . . . . . . . . . . . 156Appendix 2: Derivation of Stokes law and the Navier-Stokes Equation: A crash-coursein uids . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15716 Gamma ray spectroscopy 17916.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17916.2 Objective . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18416.3 Preparatory Questions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18416.4 Supplies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18516.5 Suggested procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18516.6 Data analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18516.7 Format of report . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18716.8 Discussion and topics for your report . . . . . . . . . . . . . . . . . . . . . . . . . . 187Appendix 1: Gamma sources available . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18717 Charge Transport 18917.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18917.2 Noise in resistive devices . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18917.3 Signal averaging . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 193vi CONTENTS17.4 Summary of Noise and Averaging . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19317.5 Four point probe techniques . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19417.6 Objective . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20117.7 Supplies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20117.8 Suggested procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20117.9 Data analysis and Discussion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20917.10 Format of report . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 209Appendix 1: Solving the van der Pauw equations numerically . . . . . . . . . . . . . . . . 210Appendix 2: Electrical Resistivity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 211Appendix 3: Measuring Resistive Devices . . . . . . . . . . . . . . . . . . . . . . . . . . . 220Reference Data 22717.11 Periodic Table of the Elements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 227Bibliography 2291PH255 Course Syllabus1.1 Course Content & DescriptionExperimental work in the topics that form the subject matter of modern physics, including spe-cial relativity, quantum physics, atomic and nuclear structure, and solid state physics. PH255 canbe taken at the same time or following PH253.The primary purpose of PH255 is to become acquainted rsthand with some of the phenomenathat provided the empirical impetus for quantum mechanics and special relativity. These include,for example, the speed of light, the photoelectric eect, atomic emission spectra, semiconductorphysics, and nuclear decay and detection.1.1.1 Course TopicsThe course will consist of performing and analyzing most of the following experiments:Counting statistics (scintillation detector)Electron charge-mass ratioDetermination of Plancks constantSolar spectraPolarization & diractionMillikans electron charge determinationAdvanced optical spectroscopyAtomic spectroscopyPhotoelectric eectElectricale/kB determinationGamma ray attenuationGamma ray spectroscopySpeed of light determinationHall eect & superconductivityMuon physics1.1.2 Course Goals and ObjectivesGeneral Learning Outcomes for 100- and 200-level courses:1. Recognizing physics concepts that involve developing mathematical models of ordinary phe-nomena, such as weights and measures, moving objects and forces. [knowledge, evaluation,analysis]2. Knowing the scientic method and the process of critically evaluating scientic information.[knowledge, comprehension, evaluation]Anticipated Learning Outcomes for this Course12 1.2 Reporting1. Students will become familiar with scholarly and research methods. [knowledge, analysis]2. Students will be able to critically discriminate between reliable and less reliable information.[analysis,evaluation]3. Formulating the solution of a physics problem. [analysis, synthesis]4. Analyzing the accuracy of a result. [evaluation]5. Estimating the order of magnitude of a result. [evaluation]Assessment of Outcomes for 100- and 200-Level Courses1. Assessment by checklists and rubrics of laboratory reports (oral and written).2. Assessed by performing laboratory experiments that emphasize the application of the scienticmethod.1.1.3 Course FormatPH255isapurelylaboratory-basedcourse. Onsomedaystheremaybeshort(15-30minute)instructional lectures, but this will be the exception rather than the rule. Students are expected toread the relevant sections of the laboratory manual before coming to class so they can begin theirexperiment immediately upon the start of the class period.1.2 ReportingEach of component of your grade is described in more detail below. The relative weight for eachcomponent in determining your overall grade are shown in Table 1.1, and the grading scale used isdetailed in Table 1.2 at the end of this section. There are several types of reports over the entiretyof the course, each described in detail below.During the rst portion of the course, you will perform a series of 4 shorter experiments designed totake two lab sessions each. The detailed schedule can be found in Sect. 2. For these 4 experiments,you will prepare one report on each experiment. Each report must have a dierent format: oneformal written report, one short oral presentation, one short memo, and one research proposal.These reports are due within 2 weeks of nishing the relevant experiment to avoid a4% per day late penalty.During the nal 4 weeks of the semester you will perform one or two two dierent experimentswhich are slightly more involved. Some of these experiments will take two full lab periods to setup and acquire all data, some will take the full 4 weeks. Your group will choose either one twooftheexperimentsto perform, suchthatthetotal timeis 4weeks. Forthenal experiments,your group will give a 30 minute group presentation, to be scheduled during dead week at thelatest. This report can discuss your entire 4 weeks of work or a single experiment, it is your decision.P. LeClair PH255: Modern Physics Laboratory1.2 Reporting 3Table 1.1: Grading BreakdownComponent Sections section (%) total (%)Short reports Formal written 15Oral 15Memo 15Proposal 1560Final reports Oral 20Summary 525Other Laboratory notebook 10intro. expt., quiz 515Additionally, the quality of your laboratory notebook will also factor into grade determination.1.2.1 Formal written reportsOne required for the initial shorter experiments. Suggested length: 5-10 pages; no strict limit.Elaborate write-ups of the experiments are not required, but it is expected that reports will includedetailed graphs and data analysis. Though the format will vary with the experiment and your ownpreferences, templates will be provided. A suggested outline is:Purpose of the experimentDescription of experimentTheoryProcedureDataSample calculationsUncertainty analysisResults and discussionA good laboratory report should be clear enough that you can read it a few years hence and recallwhat you have done and repeat it. It is particularly important that the results be clearly presentedand their signicance and deviation from expected results understood. Grading of formal reportswill be according to the following criteria:Theoretical and experimental motivation, 10%PH255: Modern Physics Laboratory P. LeClair4 1.2 ReportingDescription of experiment, 40%Analysis of data and results, 40%Style and quality of written English, 10%Analysis should include things such as comparisons with theoretical models, statistics and erroranalysis, and plots/tables; style includes things such as references, captions for gures and tables,a short abstract, conclusions, and general proofreading; the description of the experiment need notreproduce the laboratory procedure, but should provide sucient detail for another experimenterto reproduce your results. The overall quality of your data will aect both the description andanalysis sections.1.2.2 Short oral presentationsOne required in total for the initial shorter experiments, 15 minutes duration. Following roughlythe outline above, your group will present the outcome of your experiment. Oral presentations mustbe scheduled within two weeks of the completion of the experiment, at a non-class time of yourconvenience. All group members must present. Grading of oral presentations will be according tothe following criteria:Theoretical and motivation, 30%Understanding of experiment and quality of data 40%Error analysis, interpretation, and conclusions, 20%Presentation quality, 10%A few guidelines for each section: motivation and theory should include the fundamentals only,no long derivations, critical relationships expressed; understanding should show and discuss theapparatus, calibrations employed, primary (raw) data, and reduced data plots; analysis shouldinclude how uncertainties are derived, systematic and random uncertainties, and comparison withknown values; presentation quality includes timing, clarity of message, and a smoothly-owing nar-rative.Other factors under consideration are your loudness and articulation, rate and timing, spontaneity(e.g., thinking on your feet), eye contact and expression, posture and gestures, professionalism,visual aids, and responses to questions.1.2.3 MemosOne required in total for the initial shorter experiments. Suggested length: 3-5 pages; hard limitof 5pagesinmaximum. Aconcisememorandumsummarizingtheresultsof theexperiment.The memorandum is a sort of role-playing exercise: you play the role of an outside contractor,P. LeClair PH255: Modern Physics Laboratory1.2 Reporting 5specializinginanalytical work, whohasbeenhiredbyatechnologyrmtoperformaspecicexperiment. For example, for the gamma ray attenuation experiment, you might imagine that youare to investigate the properties of candidate radiation shielding materials. You are writing thismemorandum for a very busy manager at a technology rm who has little time for (or interestin) esoteric details: you must get to the point quickly, without sacricing critical information. Atemplate will be provided. Creativity is encouraged, and the format will vary with the experimentand your own tastes. A suggested outline is:1. Background: what is the problem addressed?2. Theory: a very short (2 paragraph) outline of the physics3. Experimental calibration procedures4. Results and Discussion5. Conclusions: did you solve the problem?To what degree?6. Appendices: important, but secondary data.The grading of memos will be somewhat between that of formal reports and oral presentations, butwith brevity and precision playing a larger overall role.Theory and motivation, 10%Description of problem, 20%Description of experiment, 20%Analysis of data, results, and uncertainties, 30%Relevance of results to the stated problem, 10%Style and quality of written English, 10%1.2.4 ProposalsOne required in total for the initial shorter experiments. Suggested length: 5-10 pages; hard limitof 15 pages maximum. Another role-playing exercise! You have just completed an experiment,and are excited by the results. However, exploring them further will require research funding forstudent stipends, supplies, equipment, etc. Therefore, you will write a short (fake) proposal tothe National Science Foundation (NSF) introducing the problem at hand, your preliminary results,and a description of the proposed research and its potential impact.iA template will be provided.Creativity is encouraged, and the format will vary with the experiment and your own tastes. Asuggested outline is:1. Project summary: single-page summary of the proposed research, including intellectual meritand broader impact.2. Project Description- Introduction to the problemiJust so were clear: you are not actually submitting proposals to the NSF. This is just an exercise.PH255: Modern Physics Laboratory P. LeClair6 1.2 Reporting- Background theory and prior results by others- Initial results (i.e., the result of your experiment)- Proposed research plan (i.e., what more do you want to do, and what do you need to doit)- Broader impact of proposed research (who will it aect, student training, industry, . . . )3. Management plan (rough timeline, personnel involved, management structure)4. Equipment and other resources (both what is available and what you require further)The grading of proposals will also be somewhat between that of formal reports and oral presenta-tions, but with a stronger emphasis on the creativity of the proposed follow-up experiments.Theory and motivation, 10%Description of problem, 20%Description of existing results (including analysis), 20%Proposed experiments (including experimental feasibility and theory), 30%Impact of proposed research, management plan, 10%Style and quality of written English, 10%As with the other types of reports, a template will be provided as a guide. As with the memos,creativity is encouraged!1.2.5 Final oral presentationJust like the short oral presentation, but more so: 30 minutes in duration (5 min). The gradingwill proceedaccordingtotheguidelinesfortheshortoral presentations. Aninformal writtensummary of your nal projects is also required, details of which will be provided as the semesterunfolds.1.2.6 Laboratory notebookYou must keep a laboratory notebook as a group. Its purpose is to document your activities inthe laboratory, including experimental data and preliminary plots, procedures you followed, thelocationof electronicdata, etc. Moredetailswill beprovidedinSect. 3andinasubsequenthandout, below are some brief guidelines.1. Record what you do in such a way that you will understand it a year from now, and couldrepeat the experiment.2. Use a bound book with pages big enough to tape/glue in printed items (e.g., graphs)3. Put your name and contact information on the rst page.4. Leave a few blank pages at the beginning for, e.g., a table of contents, contact informationfor lab partners, useful constants, etc.P. LeClair PH255: Modern Physics Laboratory1.3 Laboratory Safety 75. Spread out leave the left-hand page blank in case you need it (e.g., analysis, follow-up notes)6. Enter your notes chronologically and date each page, even if working on several labs at once.Also note who you are working with.7. Write down notes before, during, and after you work with equipment. Include schematics orsketches of the equipment, block diagrams illustrating functional relationships, etc. Do nottake notes on separate pages and copy them in.8. Record all measurements in raw form, do conversions/calculations as a second step. Alwaysinclude units!9. Do progress checks as you go along quick graphs, analysis, computations. This is a goodway to catch glitches or bad data, and is the essence of experimental work!10. Before you leave the lab, take the next step by entering your into the computer and doing aquick graph (if appropriate). Again, this helps you determine if your data is sucient andassess overall quality before it is too late.11. Continuetouseyourlabnotebookasyounalizetheexperimentandwritethereport.Updatedgraphs, errorcalculations, comparisonswithotherexperimenters(i.e. acceptedvalues), conclusions, ideas for improvements would be appropriate. If your notebook is donecorrectly, a short lab report comes almost directly from your notebook.1.2.7 General aspectsAll reports, of any type, must include proper citations for instance, reference data and imagesused in presentations or reports must have their source properly attributed if they are not yourown work. All quantities must include units (SI and derivative units only) and uncertainties whereappropriate. With the exception of the short oral presentations, reports are due one week afterthe completion of the experiment, with a two-day grace period. Reports not received in this timeframe will be reduced by one letter grade, with additional reductions for extreme delays. Shortoral presentations must be scheduled within two weeks of the completion of the experiment. Thenal written report is due on the last day of classes, and the nal presentations will be scheduledduring the last week of classes (a.k.a., dead week).1.3 Laboratory SafetyThe safety policies and procedures listed below must be followed in the laboratory. Failure to complywith these rules may result in dismissal or suspension from the laboratory. More importantly, failureto comply with these rules will put you at risk of injury!Be aware of the locations of re extinguishers, rst aid kits, debrillator, and emergency exits.The emergency telephone is in the hallway (dial 911 for emergencies).All accidents or injuries, however slight, must immediately be called to the attention of thelaboratory instructor who will advise the student on the course of action to be taken.PH255: Modern Physics Laboratory P. LeClair8 1.3 Laboratory SafetyUnauthorized experiments are prohibited. Follow the laboratory directions carefully, and askthe instructor before deviating from them.Food and beverages are prohibited in the laboratory.Do not remove any laboratory equipment or supplies from the laboratory.Never work in the laboratory without supervision.Eyeprotectionmustbewornatall timeswhenperformingexperimentsinvolvingliquidnitrogen or pressure vessels.The thermometers used in this laboratory may contain mercury. Mercury is toxic. Mercuryis a silvery liquid metal at room temperature. If the thermometer is broken the contentsmay spill out. Avoid skin contact with liquid mercury. Notify the lab instructor in case of amercury spill.The shielding used in some experiments is made of lead. Never handle lead without wearinggloves, and wash your hands afterward to be on the safe side.Use liquid nitrogen only according to the written instructions in the laboratory manual. Avoidskin contact with liquid nitrogen. It is extremely cold and can cause frostbite or serious burns.Liquid nitrogen is to be used in open Dewar containers only. Never pour liquid nitrogen intounauthorizedcontainers, especiallyairtightcontainers. Liquidnitrogenisacontinuouslyboiling liquid. If its volume is conned, then the vapor pressure created by the boiling liquidcan build up to dangerous levels. By dangerous, we mean shopping-for-an-eyepatch levels orworse.Never look directly into a laser beam or its direct reection or point a laser beam at someoneelse.Use care when handling electrical equipment in order to avoid electrical shock. Do not alterelectrical connections unless the relevant sources are fully powered o.Do not handle electrical equipment with wet hands.Notify the instructor in case of damaged power cords or other problems with electrical equip-ment.Careless acts are prohibited. You will know a careless act when you think of one.A more extensive discussion of laboratory safety can be found in Sec. 4.P. LeClair PH255: Modern Physics Laboratory1.4 Grading scale 91.4 Grading scaleFinally, here is the grading scale that will be used to determine letter grades at the end of thesemester.Table 1.2: Grading ScaleGradeLetter Numerical Min. % DescriptionA+ 4.33 97%Superior ability or attainment signicantlybeyond all minimum expectationsA 4.00 93%A- 3.67 90%B+ 3.33 87%Good ability or attainment which meets andexceeds many minimum expectationsB 3.00 83%B- 2.67 80%C+ 2.33 77%Ability or attainment which is acceptable andmeets all minimum (required) expectationsC 2.00 73%C- 1.67 70%D+ 1.33 67%Ability or attainment which does not meet allminimum (required) expectationsD 1.00 63%D- 0.67 60%F 0.00 0-59% Not appropriate for a minimum professionallevel of performancePH255: Modern Physics Laboratory P. LeClair10 1.4 Grading scaleP. LeClair PH255: Modern Physics Laboratory2Experiments & Schedule2.1 Shorter experimentsShorter experiments for the beginning of the semester are designed to take two lab periods for setup,data collection, and cursory analysis. Full analysis and reporting will be carried out as homeworkduring the following week. Each group will choose four experiments from the list below to performduring the rst portion of the course:1. speed of light2. counting statistics and gamma ray attenuation3. observation of atomic and thermal spectra4. electron charge to mass ratio (e/m) and photoelectric eect (h/e)5. polarization and diraction6. interferometry7. absorption spectroscopy8. Plancks constant and Boltzmanns constantThese will have a variety of reporting requirements, as detailed in the syllabus (Sec. 1.2). Over thecourse of these experiments, you will be required to do four reports of dierent types:1. formal written lab report2. short memo3. research proposal4. group oral presentationYou may choose which type of report you will do for each experiment, keeping in mind that youmust do one of each. You will be given basic templates and more detailed guidelines for each typeof report. There are a few specic items that we expect to see in each report (if applicable):1. Properly formatted equations, tables, and plots, suitable for Physical Review (seehttps://authors.aps.org/STYLE/). Examples will be provided.2. Proper SI units for all reported quantities.3. Correctly propagated uncertainties for all reported quantities.4. Statistical analysis of your data.5. Regression analysis / curve tting (e.g., linear or gaussian t).6. Quantitative comparison with a physical model.1112 2.2 Longer experiments7. Full citations/referencesforanyinformationincludedinthereportthatisnotyourownoriginal work. Onlinesources(e.g., Wikipedia)areacceptable, butshouldnotbeasolesource for any topic.2.2 Longer experimentsDuring the nal 4 weeks of the semester you will perform one or two dierent experiments whichare slightly more involved and more inquiry based. Some of these experiments will take two fulllab periods to set up and acquire all data, some will take the full 4 weeks. Your group will chooseeither one two of the following experiments to perform, such that the total time is 4 weeks:1. ne structure in atomic spectra (2 weeks)2. muon decay (2 weeks)3. molecular and absorption spectroscopy (2 weeks)4. superconductivity and giant magnetoresistance (2 weeks)5. Millikan oil drop (electron charge; 2 weeks)6. electron and light diraction (2 weeks)7. Giant Magnetoresistance (GMR; 2 weeks)8. analog electronics and semiconductor devices (4 weeks)9. build a new experiment (4 weeks + prior discussions)10. An experiment of your own design, subject to approval (2 or 4 weeks)For the nal experiments, your group will give a 30 minute group presentation, to be scheduledduring dead week at the latest. This report can discuss your entire 4 weeks of work or a singleexperiment, it is your decision. An informal written summary of your nal projects is also required.2.3 ScheduleFor most of the experiments above, the maximum number of students that can be accommodatedat any time is three. Given that, and the time and space constraints, we have a capacity of 12students for this course. You will be split into groups of at most three students each. You arefree to choose your own group members, but the groups must remain xed through the semester,barring any problems.The shorter experiments will be conducted by all groups following the schedule below. After theshorter experiments have nished, for the last four weeks of the semester each group will performtwo of the two-week experiments of their choosing in sequence. At any given time during the lastfour weeks, most of the possible experiments will be occupied. Therefore, it may not be possibleto accommodate every groups rst choice of experiment, but every eort will be made to grant atleast one of each groups rst request between the two experiments.P. LeClair PH255: Modern Physics Laboratory2.3 Schedule 13Week Sect. 1 (M) Sect. 2 (Th) topic reading1 27 Aug 23 Aug Introduction, statistical analysis Taylor Ch. 1-22 10 Sept 30 AugTwo-week experiment 1Taylor Ch. 2-33 17 Sept 6 Sept Taylor Ch. 44 24 Sept 13 SeptTwo-week experiment 2Taylor Ch. 5, 65 1 Oct 20 Sept Taylor Ch. 76 8 Oct 27 SeptTwo-week experiment 3Taylor Ch. 87 15 Oct 11 Oct Taylor Ch. 98 22 Oct 18 OctTwo-week experiment 4TBD9 29 Oct 25 Oct10 5 Nov 1 NovFinal experiments 11 12 Nov 8 Nov12 19 Nov 15 Nov13 26 Nov 29 Nov14 3 Dec 6 Dec Dead week / nal presentationsPH255: Modern Physics Laboratory P. LeClair14 2.3 ScheduleP. LeClair PH255: Modern Physics Laboratory3The Care & Feeding of Laboratory NotebooksOn the following page, we reproduce an excellent guide from MITs OpenCourseWare on main-taining a laboratory notebook. (This guide is available under the Creative Commons Attribution-NonCommercial-ShareAlike3.0UnitedStateslicense. Seehttp://ocw.mit.edu/terms/#ccforterms and conditions.)15RequirementsforExperimentalNotebooks MITDepartmentofPhysics (Dated:February14,2008) Learningtomaintainalaboratorynotebookisoneof the most important skills you will develop in Junior Lab. Agoodlaboratorynotebookisessentialwhenyoube-gin to write papers or to develop oral presentations sum-marizingyourexperimentaleorts.Aclearwell-written narrative that includes experimental schematics, plots of rawdata,anddetailsofyouranalysismethodswillen-ableyoutoreceivequickfeedbackandassistanceduring labsessionsfrompeers,TAsandsectioninstructors. Apoorlymaintainednotebookwillproveimmensely frustratingtoyouandyourinstructor.Itisverydi-culttoanswerquestionslikewhydidnttheexperiment workorwhywasmyresultobyanorderofmagni-tude?without being able to clearly and easily trace your eortsusingyournotebook.Dontcountonbeingable torecallthegainofyouramplierevenonedayaftera labsession!!!Thefollowingisalistofspecicguidelines tofollowwhenperforminglaboratorywork. 1.Create a descriptive table of contents and make an entryeverytimeyouaddnewmaterial: Date- Contents- PageDont usegenericentrieslikeDay1orAnalysis.In-stead,producerecordsofsignicantmilestones: e.g.CalibrationofNaIScintillationCounter UsingBa-133andNa-22CheckSources,Plot ofmonochromatorlinearityoverthevisiblespec-trum, Montecarlo Simulation of Mean Slant Path DistanceinMuonTOFExperiment. 2.Signanddateeachpagedemonstratingauthentic-ity. 3.Dontevererase,usewhite-out,ortearoutpages ofalabnotebook.Indicatemistakesbysimply drawing a single, neat line through the item.These mayprovetonotsoincorrectasinitiallythought and will very often be useful as a guide to how the experimentwasdoneandprovidecluesonhowto betterexecutetheexperimentnexttime. 4.Loose-leafpagesareneveracceptablewithinalab notebook.Graphicsortablesgeneratedbycom-puter must be neatly taped into the notebook.Re-membertoannotatethesetypesofgraphicswith asmuchinformationabouthowtheywerecreated aspossible. 5.Preparatory questions and solutions should be writ-teninyourlabnotebooks. 6.Followingthepreparatoryquestions,listtheob-jectivesoftheexperiment.Restatetheessential physicsoftheexperimentinyourownwords!!! 7.After listing the objectives, identify the things you will have to do, the data you must obtain and iden-tifytherequiredcalibrations. 8.Ontherstdayofanewexperimentyoushould sketchablockdiagramoftheexperimentalappa-ratus.. 9.Identifythelocationofthedatalesorlonganal-ysisprogramsiftheyaretoobigtodirectlyenter or tape into your notebook.Analysis scripts, func-tionalformsfornon-linearts,etc.shouldalways bepresentinyournotebooks. 10.Notetypicalreadingsandinstrumentalsettings sotobeabletoquicklysetupanexperimenton subsequentdays. 11.Sketchwaveformsatvariousplaceswithinthesig-nal chain.This will help ensure your understanding of each component and permit you to rapidly iden-tifyequipmentfailure. 12.Whentabulatingdata,makeneatcolumnswith headingsandalwaysnotecorrectunits. 13.Dont wait until after the session has ended to visu-ally examine the quality of your data.Make prelim-inary, hand drawn plots of data, AS THEY ARE ACQUIRED.Theseinitialplotswillveryoften saveyoutimeandfrustrationinmakingsurethat yourdataarereasonableandsuggestiveofthebe-havioryouexpect.Theimportanceofmaking preliminaryplotsandanalysesinreal-time cannotbeoverstated. 14.Yournotebookshouldcontaindiagrams,narra-tives,tablesofrawdata,formulas,computations, reduceddata,erroranalysisandconclusionsina neatcompact,orderlyarrangement. Bringyournotebooktoeverylabsessionand toalloralexams.Failuretodosowillresultin penaltiestoyourgrade! 4Laboratory SafetyIt is required that you read this entire section before doing any PH255 lab work. After reading thesafety information below, please print and sign the lab safety rules acknowledgment form on page 24.UA safety information and procedures can be found at http://bama.ua.edu/~ehs/.4.1 General rulesTwo primary rules for lab safety are that you never work alone in the lab, and you never operateequipment without proper training. At least one other person must be present in the lab for you towork on any experiment or exercise. The instructor will usually be happy to assist you if you needany extra time in the laboratory beyond normal class hours. Proper training includes reading thelaboratory procedure for a given experiment and asking the instructor for a quick demonstrationof the operation of the equipment involved. A short summary of some of the basic rules:If you dont know what you are doing WITH CERTAINTY, ask for help.Dont assume that you can just gure it out, ask for proper instructions.Make sure you are trained on all equipment and procedures before beginning.Never work alone.If you must work alone,see the preceding rule.If others urge you to follow unsafe practices, refuse.Taking shortcuts to speed up an experiment is not only potentially dangerous, it usually hasthe opposite eect in the end. A hastily done experiment usually needs to be repeated.If an injury occurs, remain calm, dial 911, and only provide rst aid if you are absolutelycertain of what to do.Other general rules are to always put things back in their proper place when you are nished, andleave the lab in a better condition than you found it. This is more than just a common courtesy toothers working in the lab, safety and organization go hand in hand.4.2 High Voltage Safety & Electronic Equipment ConsiderationsSome of the exercises and experiments in this course involve the use of high voltage. To ensure yourown safety and to prevent damage to equipment in the lab, certain precautions must be followed.1718 4.2 High Voltage Safety & Electronic Equipment ConsiderationsWhile OSHA denes high voltage to be anything in excess of 600 V, for the purposes of thiscourse, we will treat all electrical devices as if they had high voltage present.Beforeconnectingordisconnectinganycable, makesurethatthepowersupplyisintheSTANDBY or OFF mode. NEVER connect or disconnect a cable with power supplied.Never, ever work alone. If an electrical accident does occur, having a lab partner present maybe the dierence between life and death. We have rst-hand experience in these matters.Some supplies have capacitors inside which may not be discharged for a considerable amountof time after powering o the supply. Do not open any electrical equipment unless instructedto do so and supervised by an instructor.Always keep one hand in your pocket or behind your back when testing any circuit in whichthere may be high voltage present. This will help prevent an electrical shock from sourcingcurrent through your heart.Remember that it is current that kills. A good (e.g., sweaty) connection of 6 V across yourbody can kill as well as a poor connection of 600 or 6000 V.Unless specically instructed to do so, do not change the polarity of an applied voltage. Underno circumstances change the polarity with the high voltage on, as this will damage the powersupply.Gas discharge tubes (e.g., for atomic spectra) use a 5000 V dc supply. Never insert or removea tube while the power is on, and never touch the metal connectors on the ends of the tubewhile inserting or removing a tube. Only handle the central glass portion of the tubes. Thetubes may also become hot after operation, let the tubes cool down before attempting toremove them.Whenyouhavenishedyourexerciseorexperiment, powerdownall electronics(exceptcomputers, they stay on).Keep all cable ends and connectors o the oor. If a cable ends or connector get stepped on,it will be damaged, and the mating connector will also be damaged when you attempt to putthem together. Connectors and cables cost anywhere from $10 to $100 each the damagebill adds up quickly!Electrical equipment represents the large majority of potential hazards in the lab, particularly interms of risk indexed against opportunity. There are many sources of moderate or high voltage, andmany occasions to operate electronic equipment. However, if you follow proper safety procedures,the risk to you is negligible.Electricity is potentially dangerous because your body operates via electrical nerve impulses. Evena small amount of external current can disturb or interrupt such transmissions. The amount ofcurrent is what matters, as shown in the table below.iiSource data fromhttp://www.allaboutcircuits.com/vol_1/chpt_3/4.html. This page has an excellent dis-cussion of electrical safety.P. LeClair PH255: Modern Physics Laboratory4.2 High Voltage Safety & Electronic Equipment Considerations 19Bodily eect dc 60 Hz ac 10 kHz acSlight sensation Men = 1.0 mA 0.4 mA 7 mAfelt at hand(s) Women = 0.6 mA 0.3 mA 5 mAThreshold of perceptionMen = 5.2 mA 1.1 mA 12 mAWomen = 3.5 mA 0.7 mA 8 mAPainful, but voluntary Men = 62 mA 9 mA 55 mAmuscle control maintained Women = 41 mA 6 mA 37 mAPainful, unable to Men = 76 mA 16 mA 75 mAlet go of wires Women = 51 mA 10.5 mA 50 mASevere pain, Men = 90 mA 23 mA 94 mAdiculty breathing Women = 60 mA 15 mA 63 mAPossible heart brillation Men = 500 mA 100 mAafter 3 seconds Women = 500 mA 100 mAKeep in mind that these gures are only approximate, and will vary from individual to individual.However, note that with more than just a few milliamperes, you cantletgo of the electricalsource. With good contact, your arm-to-arm resistance is about 1 k. A normal 110 V ac walloutlet thus gives 110 mA, more than enough to kill you if improperly handled!Ifsomeoneinthelabdoes receiveanelectrical shock, rstturno thepowerto theoendinginstrument or pry the victim o with insulated materials (gloves, yardstick, plastic). Apply CPRif you know how (you have learned CPR, right?), and have someone immediately dial 911.Some other important suggestions if an accident occurs:If you dont know what you are doing, GET HELP.Double check that the power is o, and tape its power switch o so no one else can turn iton.Use a plastic-handled screwdriver to short out the device before touching wires or electrodes.If you need to move the oending wire(s), use a long insulating item, such as a wooden meterstick.If you must touch the oending wire(s), keep one hand in your pocket, touch the wire withthe back of your hand rst (higher resistance, no chance of grabbing and not being able tolet go).Never, EVER work alone.Be sure all electrical equipment is grounded in at least one place, and do not defeat the thirdpin on electrical plugs.PH255: Modern Physics Laboratory P. LeClair20 4.3 General Precautions When Using Lasers4.3 General Precautions When Using LasersThe helium-neon and diode lasers used in the laboratory have a total beam power of 1.022 MeVe+(+)e()Figure 16.3: Illustration of pair production.A gamma enters the detector from the left with energy E >1.022 MeV, producingan electron-positron pair in the detector. The positron is annihilated producing two 511 keV gammas.will produce two 511 keV gammas moving in opposite directions, only one of which may possiblyenter your detector if the annihilation occurs outside the detector. Positrons can only travel veryshort distance before being annihilated, meaning annihilation almost always occurs in the sourcematerial. The result is a 511 keV photopeak and Compton distribution in the gamma spectrum, asshown in Fig. 16.4.Gammas with energies greater than 1.022 MeV can enter your detector and interact by pair pro-duction, producing a positron inside the detector, as shown in Fig. 16.3. Annihilation occurs sorapidly that the light produced by the two 511 keV gammas combines with the light produced fromthe total kinetic energies of the electron and positron to produce a pulse that represents the energyof the original gamma. This appears as a photopeak pulse. Sometimes one or both of the 511 keVgammas escape the detector, and this creates photopeaks that are missing 511 keV of energy (rstescape peak) or 1.022 MeV (second escape peak).0 200 400 600 800 1000 1200 14001001k10k1274 keV511 keVannihilationpeak 22NaIntensity (counts)E (keV)Figure 16.4: Gamma spectra of22Na, showing a 511 keV annihilation peak..Two other mechanisms are worth noting, though they do not change the essential physics of thePH255: Modern Physics Laboratory P. LeClair184 16.2 Objectiveproblem.iiA fourth mechanism, Rayleigh scattering, corresponds to the elastic (photon-energy-conserving) scattering of light, which simply changes the direction of incident photons. Since noenergy is lost, this process will merely reduce the measured intensity of radiation (because somephotons will be deected out of the detection region) and will not alter the spectrum.Finally, in principle must also consider direct absorption of incident photons by the nucleus itself,photonuclear absorption. This process usually results in the ejection of one or more neutrons and/orprotons. This interaction can contribute 510% to the total photon interaction, though withina fairly narrow energy region usually occurring somewhere between 5 MeV and 40 MeV. At theenergies of the present experiment (