Physics 128b: Experimental Physics
Professor Jeffrey D. Richman
Broida Hall 5131, 893-8408
(This syllabus and other information is available from this web
Welcome to Ph128b!
Rich Harding, Developmental Technician, 893-2553, firstname.lastname@example.org
Daniel Duarte, graduate teaching assistant, email@example.com
Alfredo Alexander-Katz, graduate teaching assistant, firstname.lastname@example.org
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
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."
Research Methodology: be systematic and organized; repeat measurements
to check for reproducibility; vary experimental parameters one by one;
understand what the apparatus does-don't just treat it like a black box;
record all the relevant conditions of your measurements; make lots of plots
of your data and try to understand what's going on-don't just list the
numbers in your logbook without scrutinizing them.
Research Mind-set: be a careful observer-don't just record what you expect
to see, or what somewhat told you that you ought to see---record what you
actually do see; be skeptical-think of ways in which you might have
made an error or overlooked an important effect; estimate meaningful error
bars, don't just cook something up (I can easily tell the difference!).
Research Habits: be professional in how you work with your partner
and with the equipment; use your time well; pay special attention to safety
issues; record your data carefully and honestly.
You will choose four experiments, spending two weeks on each one. The
list of possible experiments for this quarter is:
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!
Nuclear magnetic resonance
X-ray diffraction crystallography
Quantum Hall effect
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:
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:
Look for safety-related information in the lab manual.
Look for safety-related information in the manuals for the equipment.
Ask me, the T.A.s, or Rich Harding about anything that concerns you.
Record important safety-related information in your logbook.
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.
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.
Electrical hazards (high voltage);
High-field magnets can pull tools out of your hands.
Liquid nitrogen and liquid helium (vacuum lab, surface plasmons, quantum
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
THE MOST IMPORTANT RULE OF THIS CLASS, WHICH
MUST NOT BE BROKEN IS:
You may work on an experiment
after class hours, but there must always be at least two students together
in the room.
The requirements are:
To determine your final course grades, I will use the following weighting:
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.
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.
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.
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.
Goals of the Class
Experiments + logbooks: 75%
Abstract and Paper: 17%
There are several different goals for this class.
Learn to work in a laboratory. We are trying to train you not just in physics
knowledge, but also in the methods of working scientists in almost any
Develop an approach that is systematic, methodical, careful, and organized.
Be tough-minded and skeptical.
Prepare ahead of time and try to anticipate the issues that you will need
to address. This is extremely helpful in using your time in the lab efficiently.
In many real-world experiments, you have limited access to a shared piece
of equipment, such as an expensive telescope, and preparing yourself in
advance gives you a much better chance to complete your investigation within
the allotted time.
Understand the sources of experimental uncertainty and the limitations
of your apparatus. Effort spent on understanding how your equipment works
is almost always rewarded with more reliable results.
Learn how to record results and how to describe your setup and procedures
so that the conditions under which your results were obtained are completely
Learn proper methods of data analysis.
Learn how to draw conclusions that are specific, meaningful, and justified.
Learn some modern physics. In your classical mechanics and electromagnetism
classes, you are learning physics that was developed about 100 years ago;
in quantum mechanics, you are learning physics from the 1920s and 1930s.
In this class, you will learn some physics that is based on much more recent
work. This will be challenging, since you may not have encountered much
of this physics in your theoretical classes.
Learn skills for giving talks and writing papers. These skill have a very
wide applicability. They are extremely important in any scientific field
and in many non-scientific jobs as well.
Learn to obtain information from many sources, not just a single textbook.
Schedule: dates are specified as M, W (T, Th) for each week.
||Jan 6 (7)
||Jan 11, 13 (12, 14)
||Orientation, Expt 1
||Jan 18x, 20 (19, 21)
||Expt 1 x=MLK holiday
||Jan 25, 27 26, 28)
||Feb 1, 3 ( 2, 4)
||Feb 8, 10 (9, 11)
||Feb 15, 17 (16, 18)
||Expt 3; talks on Feb 15, 17
||Feb 22, 24 (23, 25)
||Mar 1, 3 (2, 4)
||Mar 8, 10 (9, 11)
||Mar 15, 17 (16,18)
||Finals week: paper due Mar
Some important dates:
Grading of Logbooks (changed slightly from Fall quarter)
For the M, W section, the talks will be on Mon, Feb 15
For the T, Th section, the talks will be on Tues, Feb 16
For the M, W section, there is one holiday, Monday, Jan 18. For this reason,
the M, W section will start its experiments on Weds., Jan 13.
The papers will be due on Thurs., Mar. 25. Note, however, that since
you can write the paper on any experiment except the one that you give
your talk on, you could in principle hand it in earlier!
J.R. at Fermilab on Jan. 14, 15; at SLAC Feb 18, 22-25.
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
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
A title slide, with title, authors, and main goals of the experiment.
2-4 of slides on theoretical background.
2-4 slides on the method.
2-4 slides on the results and conclusions.
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:
Methods and Procedures
Interpretation and Discussion
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
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
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.