8.13-14 | Fall 2016 | Undergraduate

Experimental Physics I & II "Junior Lab"

Syllabus

Course Meeting Times

Labs: 2 sessions / week, 3 hours / session

Prerequisites

Students enrolling in 8.13 Experimental Physics I are expected to have recently completed 8.04 Quantum Physics I.

Students enrolling in 8.14 Experimental Physics II are expected to have recently completed 8.05 Quantum Physics II and 8.13 Experimental Physics I so as to be prepared to immediately begin conducting investigations. 

Description

Junior Lab consists of two undergraduate courses in experimental physics. The course sequence is usually taken by Juniors (hence the name). Officially, the courses are called Experimental Physics I and II and are numbered 8.13 for the first half, given in the fall semester, and 8.14 for the second half, given in the spring.

The purposes of Junior Lab are to give students hands-on experience with some of the experimental basis of modern physics and, in the process, to deepen their understanding of the relations between experiment and theory, mostly in atomic and nuclear physics. Each term, students choose several different experiments from a list of 21 total labs.

Goals

The purposes of Junior Lab are to give you hands-on experience with some of the experimental bases of modern physics, deepening your understanding of the relation between experiment and theory, and — in the process — to accelerate your professional development as a scientist in skills such as oral and written communication methods, the troubleshooting process, professional scientific attitude, data analysis, and reasoning about uncertainty.

You will do experiments on phenomena whose discoveries led to major advances in physics. The data you obtain will have inevitable systematic and random errors that obscure the relations between the macroscopic observables of our sensory experience and the physical laws that govern the submicroscopic world of atoms and nuclei. You will be challenged to learn how each of the experimental setups works, to master its manipulation so as to obtain the best possible data, and then to interpret the data in light of theory with a quantitative assessment of the uncertainties. We believe you will find satisfaction in observing, measuring, and understanding phenomena many of which would have won you the Nobel Prize if you had discovered them.

Section Organization

Students in the class are assigned to a section, with enrollment less than or equal to 16 students. Each section is run independently by one faculty member with the assistance of a graduate Teaching Assistant (TA). The sections are scheduled Monday through Thursday, and the lab is also open on Fridays from 10AM to 4PM for additional lab time outside of your regularly scheduled section.

You are expected to work in pairs, sharing as evenly as possible in the measurements, the analysis and the interpretation of the data. The best choice for a lab partner may be someone who lives nearby and has a schedule that matches yours so you can get together outside of class to analyze and interpret your results. Most students find they require at least 18 hours per week to do the work of the course.

Laboratory Access

Beyond your required assigned lab time, the laboratory will be open every class day from 9AM–5PM (except for Junior Lab staff meetings) and Friday from 10AM–4PM with staff help available to discuss physics and maintain equipment. At all other times the laboratories must be kept locked for safety and security, especially the security of radioactive sources. Junior Lab students may occasionally be permitted access to the lab outside of the normal hours, but only after consulting with their TA or section leader. It is each student’s responsibility to maintain security by making sure the doors are kept locked at all times outside of the regularly scheduled sessions. One should never work alone in a laboratory, especially if high voltages are involved. A partner or instructor must be within reach.

Ethics in Science and Education

Nature is the ultimate enforcer of truth in science. You will be tempted many times in Junior Lab to tamper with the integrity of your scientific results. Do not. This hurts yourself and others. You may also be tempted to plagiarize materials for your oral and written reports. Do not. All instances of academic misconduct in Junior Lab will be punished severely. Students are highly encouraged to review the materials on MIT’s Academic Integrity website.

Please consult Junior Lab’s more extensive Ethics in Science and Education section — which you are obligated to understand — for more specific discussion.

Safety in Junior Lab

Your safety in Junior Lab is the staff’s top priority. It should be your top priority, too. The most important safety rules, which the staff will enforce diligently, are as follows:

  1. Never work alone.
  2. No eating or drinking in the lab.
  3. Treat radioactive sources according to the ALARA principle, as per your training.
  4. Obey state regulations and Junior Lab practices on access and tracking of radioactive sources, as per your training.

On the first day of 8.13, Junior Lab students receive a general safety discussion, a lab tour, and a formal state-mandated training in the use of sealed sources of ionizing radiation from a member of MIT’s Radiation Protection Program. This training is required for work in both 8.13 and 8.14. Students who will be performing experiments using biological materials, Class 3b or Class 4 lasers, or requiring access to the MIT Nuclear Reactor facility will require further formal training from MIT’s Office of Environment, Health and Safety (EHS). The Junior Lab staff will provide information on the required training as needed.

In particular, the ‘Doppler-Free Saturated Absorption Spectroscopy’ experiment utilizes a Class 3b near-IR laser operating at 40 mW of output power; the ‘Raman Spectroscopy’ experiment utilizes a Class 4 532 nm 2 W laser. As such, all users of these experiments must undergo MIT Laser Safety Training (EHS Course 371C, about 1.5 hours in length, offered by EHS every few weeks) prior to performing the experiment. All students should download the MIT Laser Safety manual and read, at a minimum, Section Two.XVI.D dealing with Class 3b laser controls.

Please consult the more extensive Safety in Junior Lab section — which you are obligated to understand — for more specific discussion.

When you read the report of a physics experiment in a reputable journal you can generally assume it represents an honest effort by the authors to describe exactly what they observed. You may doubt the interpretation or the theory they create to explain the results. But at least you trust that if you repeat the manipulations as described, you will get essentially the same experimental results.

Nature is the ultimate enforcer of truth in science. If subsequent work proves a published measurement is wrong by substantially more than the estimated error limits, a reputation shrinks. If fraud is discovered, a career may be ruined. So most professional scientists are very careful about the records they maintain and the results they publish.

Junior Lab is designed to provide preprofessional training in the art and science of experimental physics. What you record in your lab book and report in your written and oral presentations must be exactly what you have observed including date, time and who did it.

Sometimes you’ll get things wrong because of an error in manipulation, equipment malfunction, misunderstanding, or a miscalculation. The instructor’s job is to help you figure out what went wrong so you can do better next time. If circumstances in an experiment are such that you cannot get your own data (e.g. broken equipment, bad weather), you may use somebody else’s provided you acknowledge it.

Fabrication or falsification of data, using the results of another person’s work without acknowledgement, and copying from “the files” are intellectual crimes as serious as plagiarism, and possible causes for dismissal from the Institute.

The precaution about the acknowledgement of other people’s data also applies to acknowledging other people’s rhetoric. The appropriate way to incorporate an idea which you have learned from a textbook or other reference is to study the point until you understand it and then put the text aside and state the idea in your own words.

One often sees, in a scientific journal, phrases such as “Following Albert Einstein …”. This means that the author is following the ideas or logic of Einstein, not his exact words. If you quote material, it is not sufficient just to include it in the list of references at the end of your paper. You should use the following formatting:

The quote should be indented on both sides or enclosed in quotes, and attribution must be given immediately in the form of a reference note.

Importing text from a published work, from other student papers, or from the lab guide without proper attribution is a serious breach of ethics and will be dealt with by the Committee on Discipline.

Most Junior Lab experiments are concerned with data comparison measurements of well-known fundamental constants such as h, e, kB, and c, or of significant physical quantities such as the mean life of the muon or the cross section of an electron for scattering a photon. The purpose of these experiments is to give you hands-on experience with atomic and nuclear phenomena, a sense of the reality of the concepts and theories you have studied in books and lectures, and the beginning of professional skill in obtaining and recognizing reliable data and extracting meaningful results from them. There is nothing wrong with “peeking” in the CRC Handbook or any of the many relevant texts to see what your experiment should have yielded. Indeed, the way to get maximum benefit from your Junior Lab experience is to play it as a game in which you squeeze the most accurate measurement you can get out of the available equipment and the practical limits of analysis, make a rigorous estimate of the error, and then compare the results with the established value. If the established value is outside your error range, try to find out what went wrong, fix it, and try again. If the established value is in your error range, don’t rest easy, but do whatever may be necessary to prove it isn’t an accident. Repetition is the essential key to attaining confidence and errors for a result, whether of a single measurement or an entire experiment! But whatever the outcome of an experiment is, you must tell exactly what you observed or measured when you present your oral or written report, regardless of how “bad” the results may appear to be.

ACTIVITIES 8.13 8.14
Lab Performance and Attendance 10% 11%
Laboratory Notebooks 8% 8%
Homework and Exercises 6% Not Applicable
Preparatory Questions (3) 6% 6%
Oral Examinations (3) 30% 27%
4-page Written Summaries (3) 30% Not Applicable
Final Public Oral Presentation 10% Not Applicable
5-page Written Summaries (2)
including Peer Review 		Not Applicable 24%

Open-Ended Project

Project Proposal
Project Poster

Not Applicable

12%
12%

Lab Performance and Attendance

The regularity of your attendance will be a factor in determining your grade in the course, as will be your preparedness for the measurements and alternating as the “lead” (with your partner), to carry them out.

It is essential that you efficiently use all of the laboratory time assigned to you. Extra time is available, but should not be essential. Several experienced experimental physicists will be present in every scheduled session, ready and eager to answer your questions and to help you make your apparatus function properly. Calling for help when you get stuck can only improve your lab performance grade.

8.13 Students Only:

Failure to have a “dry run” of the final presentation with a Writing, Rhetoric, and Professional Communication (WRAP) instructor will result in a 2% reduction of the lab performance grade. Failure to submit the preliminary oral exam or written summary will each result in a 1% reduction of the lab performance grade. 

Laboratory Notebooks

Throughout the term, you will be required to maintain a detailed real-time record of your activities in a laboratory notebook which is provided to you by Junior Lab. To help motivate the most effective use of this critical laboratory tool, student notebooks will be comprehensively evaluated twice during the semester:

8.13 Students:

The first check will be after the preliminary experiments (this preliminary grade does not count towards the course total), and the second at the end of the semester for 5% of the final grade. In addition to these comprehensive evaluations, the notebook will also be briefly evaluated at each oral examination, each for 1% of the total grade. Please talk with your section instructors before your notebook evaluations if you have any questions. Spot checks of your notebook may also occur during lab sessions as an indicator of lab performance. Spot checks during the oral exams also provide an indicator of data quality.

8.14 Students:

The first check will be around midterm for 3% of the final grade, and the final check will be at the end of the semester for 5% of the final grade. Having already taken 8.13, you should be well versed in how to maintain a good laboratory notebook. Spot checks of your notebook may also occur during lab sessions as an indicator of lab performance, and as part of the oral exams as an indicator of data quality.

A detailed discussion of how to set up and use a scientific notebook is given in Requirements for Experimental Notebooks, a copy of which is recommended to be taped to the inside cover of your notebook for routine consultation.

Homework and Exercises (8.13 Students Only)

A number of in-class exercises will be performed during the introductory period to help you learn core scientific skills, especially data analysis. Preparation before class and follow-up practice are both necessary to maximize the utility of these exercises. Therefore, the in-class work will be surrounded by a small number of graded homework assignments.

Preparatory Questions

For each experiment, there a set of preparatory questions which point you to the essentials of the experiment, including safety information. You are expected to work out the solutions and/or predictions to the preparatory problems in your notebook and submit the answers before starting the experiment. Late solutions will not be accepted because you will need to know this material before starting the experiment: late solutions do not make sense. [Note: The preparatory questions are not available to OCW users.]

8.13 Students Only:

The preparatory questions for preliminary experiments will be graded for feedback, but will not count towards your final course grade.

Oral Examinations

For each main experiment, a one-hour total length (2 students × 30 minutes each) oral examination and discussion will be scheduled with one or more of your instructors, your lab partner, and yourself within 10 days of the last scheduled session for that experiment. You and your lab partner must both bring your lab notebooks to the exam session. All oral exams are video-recorded so that you may review your presentation technique.

Each student should prepare a 15-minute oral report on the theoretical and experimental aspects of a single portion of the experiment. This is a short time, so it is essential that you rehearse your presentation as you would if you were giving a 15-minute presentation at a meeting of the American Physical Society. Please review the Speaker Tips and Guidelines.

You must prepare your visual aids electronically (e.g. slides in the LaTeX beamer class or MS PowerPoint) for use with a digital projector in a professional-style presentation. We suggest a maximum of ten slides. Written and Oral Report Resources have detailed instructions and templates for generating your own presentations.

The theoretical section should briefly demonstrate a mastery of some portion of theory relevant to understanding the significance of the experimental results. The experimental section should dominate the discussion and demonstrate an understanding of how the equipment works, what was measured, how the data were reduced, and how the random and systematic errors were estimated. Each student must discuss different aspects of the motivating theory and experiment. Furthermore, it is not acceptable to discuss theory only or experiment only; every presentation should contain a balance! Full cooperation with lab partners and others in preparing for the oral reports is encouraged and required. This latter aspect is particularly important to ensure that both partners report the same results!

Orals exams will be graded using the following criteria:

  • Theoretical and/or experimental motivation: 15%
  • Description of experiment: 35%
  • Analysis of data and results: 35%
  • Style and English: 15%

8.13 Students Only:

To familiarize you with the examination procedure, a one-hour oral exam will be held on one of the three preliminary experiments of your choice. This oral will proceed identically as the others. It will be scored but will not count towards your final course grade. (However, as discussed above, failure to execute the preliminary oral exam will result in a 1% deduction from the overall lab performance grade for the semester.) It is designed to give you feedback on content, style and presentation without the pressure of a graded performance. Partners should choose different preliminary experiments for this initial oral exam. Video recordings of these practice orals will be used to facilitate guidance from the Lecturers in MIT’s Program in Writing, Rhetoric, and Professional Practice (WRAP) who are part of the Junior Lab staff. You must schedule a one-hour appointment for feedback with one of these instructors within a week following their practice oral.

Final Public Oral Presentations (8.13 Students Only)

At the end of the term in December, you will give a 15-minute public oral presentation which will be attended by all students in your section and any other interested parties. The last two class sessions are reserved for this purpose. The public oral presentations should be given in the style of a paper presented at a conference, with careful attention paid to the preparation of visual aids — in the form of an electronic presentation — and to the clarity of the oral discussion. Questions from classmates and the audience are encouraged, allowing for a general discussion of the experiment.

This public presentation, in addition to the four jointly prepared oral examinations given earlier in the term, is a major component of the CI-M requirement which 8.13 fulfills. Revision of past work is essential to this requirement, as it is to all formal communication. You are required to make a 1-hour appointment with a WRAP Program instructor to do a “dry run” and receive feedback at least four days prior to your public presentation. The dry run will not be graded, but, as mentioned above, failure to do it will result in a 2% reduction of the lab performance grade. Obviously, to present on an experiment in the public presentation, it must have previously been presented as an oral exam with the section instructor.

Written Summaries

8.13 Students must do three 4-Page Written Summaries:

A written summary must be prepared for each of the three standard experiments, plus the preliminary experiment that was presented orally. (As usual, the preliminary written summary does not count in the final grade, but failure to submit it will result in a 1% reduction from the overall lab performance grade for the semester, as discussed above.) The purpose, theory, and results of the experiment must be summarized in no more than 4 pages, including all figures, with a neat appearance and concise, correct English.

8.14 Students must do two 5-Page Written Summaries:

A written summary must be prepared for two of the three standard experiments. The purpose, theory, and results of the experiment must be summarized in no more than 5 pages, including all figures, with a neat appearance and concise, correct English.

You must prepare your summary individually, not as a group. All of your work on the experiment should be summarized, not just the part you chose for your oral presentation.

You must submit your written summary to your section instructor by the appointed deadline: specifically, written reports for each experiment will be due by midnight on the day after your oral exam. It is expected, however, that the paper will be essentially complete by the time of your oral exam. The delay between oral exam and paper submission allows you to correct any egregious mistakes that were uncovered during the exam so as not to repeat them in your written work and receive a double penalty!

Your summary’s organization and style should resemble that of an article in the Physical Review Letters. In particular, the abstract is essential. It should briefly mention the motivation (purpose), the method (how measured) and most importantly, the quantitative result with uncertainties.

The report must be typeset in a form that would be suitable for submission as a manuscript. To aid you in this process, we have produced a sample paper template written in LATEX that we encourage you to study and use for your own submissions. The sample paper is downloadable from Written and Oral Report Resources along with its associated .tex file.

Papers will be graded using the following criteria:

  • Theoretical and/or experimental motivation: 15%
  • Description of experiment: 35%
  • Analysis of data and results: 35%
  • Style and English: 15%
  • Papers not submitted by the deadline will be deducted 10% for each day they are late.

MIT has excellent resources for technical writing and oral presentations (including on-line writing consultations) at the CMSW Writing and Communication Center website. Use them!

Open-Ended Project (8.14 Students Only)

The open-ended project, usually occurring in the second half of the Spring term, should fall within Junior Lab’s resources and scope of modern physics, but the design and goals of the project are to be determined by the student group.

Each group will submit a single project proposal as a formal 2-page written document. The proposal is due on the Friday between Experiments 1 and 2, and will count as 10% of the total grade. As this may not allow enough time to correct malformed projects before they could begin in Experiment 2, a rough form of the proposal — which nevertheless provides enough detail for the Junior Lab staff to judge its merits — will be due two weeks earlier. This rough proposal will count for 2% of the total grade, and will be graded as either a 2 (for an adequate proposal), 1 (for a proposal which shows little thought), or 0 (for no proposal). It is expected that all groups should receive full credit on the rough proposal. After all proposals are received, the Junior Lab staff will serve as a review committee which will: determine if any proposals are making competing requests for resources, and attempt to adjudicate such conflicts; determine if any proposals have components which are beyond the scope of the program, and scale back these components; and approve a coordinated schedule for the projects to go forward.

Projects will be evaluated based on a scientific poster of comparable detail to the reports due for the other experiments, prepared and presented by the group at a poster session at the end of the semester, making up 10% of the total grade. There is no oral report or written summary for the project. Criteria for grading are themselves open-ended, but will largely reflect how well the project goals were pursued — or adapted, in the case of unforeseen circumstances.

The poster will be preceded by a draft for 2% of the total grade, graded similarly to the rough proposal. Each poster will be peer-reviewed by other students. The written peer-review report of other students’ projects will count for 8% of the total grade.

Required Readings

Bevington, Philip R., and D. Keith Robinson. Data Reduction and Error Analysis for the Physical Sciences. Boston: McGraw-Hill, 2003. ISBN: 9780072472271.

Experimental Lab Manuals by the Junior Lab staff (available inside every Experiment page)

Ethics in Science and Education by the Junior Lab staff 

Laboratory Safety and Regulations in Junior Lab by the Junior Lab staff 

Melissinos, Adrian Constantin. Experiments in Modern Physics. New York: Academic Press, 1966. (Out of print. May be available in academic libraries.)

Melissinos, Adrian Constantin, and Jim Napolitano. Experiments in Modern Physics. San Diego: Academic Press, 2003. ISBN: 9780124898516.

Consult both before and during your investigations. This text is only “Recommended” because the Junior Lab staff feels it is too expensive to “Require.” Material which is essential to the understanding of an experiment and which can be found in the Melissinos text is generally omitted from the lab manuals. The Physics Reading Room on campus has both editions which offer different material: you should consult them both!

Other Useful Texts

Preston, Daryl, and Eric Dietz. The Art of Experimental Physics. New York, NY: John Wiley & Sons, 1991. ISBN: 9780471847489.

Taylor, John Robert. An Introduction to Error Analysis: The Study of Uncertainties in Physical Measurements. Sausalito, CA: University Science Books, 1997. ISBN: 9780935702750. (This book covers much of the same material as Bevington and Robinson and is easier to read.)

Gregory, Philip Christopher. Bayesian Logical Data Analysis for the Physical Sciences: A Comparative Approach with Mathematica® Support. Cambridge, UK: Cambridge University Press, 2006. ISBN: 9780521841504.

Reference Articles and Equipment Manuals

At this stage of your training as an experimentalist, you should realize that there is no ‘comprehensive’ or perfect textbook. Much of the material you will need to dig into are the early journal papers which originally detailed many of these important discoveries.

For more information on Technical Writing, please refer to The Mayfield Handbook for Technical and Scientific Writing.

8.13 Experimental Physics I Schedule Summary

The first few class sessions will familiarize you with the lab, giving everyone a common foundation in experimental techniques, data analysis, collaboration skills, oral and written communication, and computing tools including MATLAB and LaTeX. The first two sessions are dedicated to important organizational and administrative issues, plus important safety information and an introduction to the basics of work in 8.13.

Next, two 3-hour sessions are scheduled for each of three short preliminary experiments:

  • Optical Interferometry
  • The Photoelectric Effect
  • Poisson Statistics

For useful information on how to prepare for these first experiments, see The Purpose and Format of Junior Lab Preliminary Experiments (PDF).

The second day of each preliminary experiment will include further instruction and in-class exercises on foundational skills. Your work on the preliminary experiments will be graded for feedback, but will not count towards the final course grade.

Following this introductory period, you will plan, execute, analyze, and report on three longer experiments. The first will be executed in 5 sessions, while the last two will be performed in 4 laboratory sessions each. The sequence of experiments performed by each student group is determined by the section leader as early as possible in the semester, based on student preferences. To ensure a proper variety of physical techniques are experienced, you must perform at least one — but no more than two — of the following 5 experiments:

  • Compton Scattering
  • Relativistic Dynamics
  • The Speed and Mean Life of Cosmic-Ray Muons
  • Rutherford Scattering
  • X-Ray Physics

The remaining experimental options are:

  • Optical Emission Spectra of Hydrogenic Atoms
  • Optical Trapping
  • Pulsed NMR: Spin Echoes
  • 21-cm Radio Astrophysics
  • The Frank-Hertz Experiment
  • Johnson Noise and Shot Noise

The term culminates in a week-long series of public oral presentations given by you and your fellow students to peers, friends, and faculty in the style of a parallel session at an American Physical Society conference.

8.14 Experimental Physics II Schedule Summary

The first class period will be dedicated to selecting partners, choosing the first experiment, and brief introductory remarks by the section instructors. The remainder of the term will be divided into four experimental sessions of 5 days each. Experiments for three of the four sessions will be selected from the standard Junior Lab Experiments menu, while the fourth will be an open-ended project of your own design. (For scheduling reasons, the open-ended project will not occur during the first experimental session.)

Before the second experiment begins, each student group will propose a schedule for the use of the remaining three experimental sessions, most notably including the open-ended project, the scientific goals of which should be defined in the proposal. A brief draft proposal will be due near the middle of the first experiment, while a more formal two-page written proposal will be due near the end. Proposals should outline the required resources and scheduling constraints for the open-ended project. Projects beyond the scope of Junior Lab will be identified and scaled back at the draft proposal stage. Examples of projects include:

  • Deeper exploration of a previously performed 8.13 or 8.14 experiment
  • Performing an experiment still under development by the Junior Lab staff
  • Assembling and performing a simple Junior Lab style experiment from the American Journal of Physics
  • Other projects subject to approval

The project schedule:

  • Rough draft project proposal: Due at the end of the second week of the semester
  • Two-page project proposal: Due on the Friday between Experiments 1 and 2
  • Execute project: During time period proposed, usually during the second half of the semester
  • Draft poster presentation: Due about two weeks before the end of the semester
  • Final project poster presentation: Usually done on the last day of the semester

The open-ended project will be evaluated based on a scientific poster prepared by the group and presented in an open poster session at the end of the semester. The student group judged by the 8.14 teaching staff to have proposed and performed the best original project of the year will be awarded the annual Edward C. Pickering Award for the most Outstanding Original Project in the MIT Physics Junior Lab. Note that the additional fifth day per experiment (beyond what you had in 8.13) raises the level of expectations regarding the completion of “challenging” aspects of the lab manuals and an expectation to exceed the standard material.

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