Physics 128b: Experimental Physics
Winter 1999
Professor Jeffrey D. Richman
Broida Hall 5131, 893-8408
(This syllabus and other information is available from this web page.)



Welcome to Ph128b!

Having survived Ph128a, you are now ready for Ph128b. Last quarter, you learned that for your work in the laboratory to be effective, you have to invest a large amount of time and effort into discovering what is really going on.. Many students learned that this can be a lot of fun!

I have tried to emphasize a central point about this course. Our main goal is to train you in the methodology, mind-set, and habits of a research scientist. This goal sets this course apart from the usual physics lecture course, where the main goal is to teach you physics, as well as problem-solving skills. Here are some characteristics of a research-oriented approach:

These characteristics are what we are trying to develop. I have heard some students say that when they work in labs for a certain professor, that they don't have to do all the things that I require in Ph 128. My advice is: you should do them anyway! You should (1) make a safety assessment for each new experimental situation; (2) develop a plan at the beginning of each session in the lab, with an outline of what you expect to do and accomplish; (3) record all of your procedures and experimental conditions, making clear diagrams of the setup; (4) carefully record and interpret you data; and (5) understand the relevant theoretical issues. The reasons for all of these things are discussed in a separate handout, "What You Should Write In Your Logbook."

The Experiments
You will choose four experiments, spending two weeks on each one. The list of possible experiments for this quarter is:

  1. Mossbauer effect
  2. Molecular spectra
  3. Nuclear magnetic resonance
  4. Surface plasmons
  5. X-ray diffraction crystallography
  6. Zeeman effect
  7. Quantum Hall effect
  8. Vacuum Techniques.
Last quarter, many students began to appreciate that each experiment was really just an introduction to a broad topic. Each topic could be explored far beyond what we do in the two-week lab, and this statement could be made even more strongly about Ph 128b. For example, you can have a career working in nuclear magnetic resonance or X-ray crystallography!
As for last quarter, you are strongly encouraged to make use of our lab library, which I am continuously adding books to. Don't feel restricted to this library, however. Some students made very good use of the UCSB library last quarter and found some extremely useful references.

The last experiment listed above, vacuum techniques, was also available during Ph 128a, but several groups did not do it. Since it is good experience, we have set it up for this quarter also.


There are important safety issues in some experiments. This is particularly important in Ph 128b, where we use an X-ray machine and radioactive sources, but there are also safety issues in some of the Ph 128a experiments. I require that you start each experiment by doing an assessment of the safety issues. Please work like a professional and be actively involved in your own safety:

  1. Look for safety-related information in the lab manual.
  2. Look for safety-related information in the manuals for the equipment.
  3. Ask me, the T.A.s, or Rich Harding about anything that concerns you.
  4. Record important safety-related information in your logbook.
Usually, it doesn't take long to inform yourself about safety issues, and it is well worth the trouble. Some typical examples of safety hazards are:
  1. Intense light sources: lasers or gas discharge tubes. Never look directly into a laser beam. In addition, be careful not to look into a mirror or other polished surface that may reflect laser light directly into your eye. When working with lasers, it is always a good idea to keep the level of your eyes substantially above the level of the laser beam. Avoid looking directly at gas discharge tubes. In some experiments, we have provided eye goggles. If you would like a pair but they aren't around for some reason, feel free to ask us and we will get some.
  2. Electrical hazards (high voltage);
  3. High-field magnets can pull tools out of your hands.
  4. Liquid nitrogen and liquid helium (vacuum lab, surface plasmons, quantum Hall effect)
  5. X-ray machines, radioactive sources (Ph 128b). Note that you must wear a film badge to work in the room for these experiments (Mossbauer effect, X-ray crystallography). This film badge will be specifically signed out to you.
If any type of accident occurs, you must report it as soon as possible to the instructor, Rich Harding, or one of the T.A.s. If for some reason, there is an emergency and no one is around, you can go to the Physics Department Office on the third floor and ask someone to call 9-911.


You may work on an experiment after class hours, but there must always be at least two students together in the room.

Class Requirements

The requirements are:

  1. Do four experiments, and keep a good logbook record of each one. The logbooks should not just be spiral notebooks. Please keep two separate logbooks to facilitate grading; the T.A.s will grade one while you are using the other for your next experiment.
  2. Give one talk; this will be after the second experiment, and it can be on either of the first two experiments. You will give this talk jointly with your lab partner using transparencies and an overhead projector. We will provide blank write-on transparencies, but you should get your own pens. The best ones are Staedtler Lumocolor Fine-point permanent pens. You may also use a computer to generate your talk. You will then need to use a different kind of transparencies.
  3. Write one abstract. The abstract is about one paragraph long and will be due after the third experiment. It can be on either of the experiments that were not the subject of your talk.
  4. Write one full scientific research paper. The paper will be due after you complete all four experiments, but it may not be on the same experiment as the one your give your talk on. It may be on the one you have written your abstract for, but in general you will need to rewrite your abstract.
To determine your final course grades, I will use the following weighting:
  1. Experiments + logbooks: 75%
  2. Talk: 8%
  3. Abstract and Paper: 17%
Goals of the Class

There are several different goals for this class.

Schedule: dates are specified as M, W (T, Th) for each week.

Dates Remarks
Jan 6 (7) Orientation, reading
Jan 11, 13 (12, 14) Orientation, Expt 1
Jan 18x, 20 (19, 21) Expt 1 x=MLK holiday
Jan 25, 27 26, 28) Expt 1
Feb 1, 3 ( 2, 4) Expt 2
Feb 8, 10 (9, 11) Expt 2
Feb 15, 17 (16, 18) Expt 3; talks on Feb 15, 17
Feb 22, 24 (23, 25) Expt 3
Mar 1, 3 (2, 4) Expt 4
Mar 8, 10 (9, 11) Expt 4
Mar 15, 17 (16,18) Finals week: paper due Mar 25

Some important dates:

Grading of Logbooks (changed slightly from Fall quarter)

The logbooks will be due one week after you complete the experiment. Thus, for the M, W section, the logbooks will be due on the W following the two week period for the experiment; for the T, Th section, they will be due on the Th following the two week period for the experiment. The logbooks will graded on a scale from 1 to 50. Late logbooks will be accepted, but with 3 points deducted for each day late. If special circumstances arise, please discuss them with me as soon as possible.
Talks (same as Fall quarter)
Each group will give a 15 minute talk, which will be followed by 5 to 10 minutes of questions. The talk should contain

  1. A title slide, with title, authors, and main goals of the experiment.
  2. 2-4 of slides on theoretical background.
  3. 2-4 slides on the method.
  4. 2-4 slides on the results and conclusions.
All together, you should have 8-12 slides. Please label all plots and give the units for all quantities. The talks will be timed with a hard cutoff, so you should practice your talk to

make sure that it fits into 15 minutes. Sometimes, extra or "backup" slides are useful during the question period. The talk should be divided between the two lab partners, with roughly equal time for each student.
Paper (slightly changed from Fall quarter-see "Conclusions")
The paper should contain the following sections:

  1. Abstract
  2. Theoretical Discussion
  3. Methods and Procedures
  4. Results
  5. Interpretation and Discussion
  6. References
The abstract

The abstract is meant to be a stand-alone description of the work-it should succinctly state what was done and what the results were. It should not refer to any other section of the paper, and it should not go into the theory, except perhaps very briefly. An abstract should not read like an introduction, which contains background information and is not a summary of the results. You should include the numerical values of important measurements, with their uncertainties. A person opening up the journal to your article will read the abstract first. If they are busy, this may be all that they will ever read! 

You should write a section on the theory behind your experiment. Do not mix your results or interpretation into this section, which should be 2-4 pages. (If you want to write more, it's fine with me.)
Experimental Methods and Procedures
Include at least one clear diagram of the experimental setup. Be sure to describe your experimental methods in detail. The length of this section will depend on the experiment that you did, but as a guideline, it should be between 3 to 5 pages. Detailed figures add a lot to the clarity of such descriptions.

Tables are great for summarizing results. In some cases, graphs are preferable to tables, since they make it much easier to see relationships in the data. In fact, a lot of students miss important observations because they don't bother to graph their data. Be sure to include a discussion of how you estimated your experimental uncertainties in the raw data and how you propagated these uncertainties into your final results.
Discussion and Interpretation
I prefer to have the interpretation of the results in a separate section from the results themselves, since it explicitly separates what you measured from your interpretation. This rule may not apply to all situations, so if there is a strong reason to combine this section with that on Results, you can do that.
I didn't require you to write this section last quarter, but any scientific paper has one. This section, one or two paragraphs long, is quite similar to the abstract but need not be quite as terse and bare bones. Very often, when I read a paper I do the following: (1) read the abstract, (2) look at the figures and tables, (3) read the conclusions. Most of the time, that's all I have time for. If the paper is very important, I'll read the rest!
If there are important theoretical or experimental results that you wish to use in your paper, they should be referenced. In the body of the text, put a reference number, and  list the references in numerical order in this section.
Good luck!