notes on PE effect
A.N James on the PE
PE effect and
Radiation Safety - READ BEFORE STARTING EXPERIMENT
will need to obtain a radiation badge (see
instructions). It takes several weeks to arrive, so plan
Radiation Safety - READ BEFORE STARTING EXPERIMENT
Note: You wil not need a radiation badge for this experiment
| Zeeman effect
Equipment and procedure
- The TeachSpin
Pulsed and continuous wave NMR
- Hahn, E. L.,
"Free nuclear induction", Physics Today, Nov. 1953, pp. 4-9.
- Hahn, E. L., "Spin echoes", Phys. Rev., 80,
- Carr, H. Y., and E. M. Purcell,
"Effects of diffusion on free precession in nuclear magnetic resonance
experiments", Phys. Rev., 94, 630-638 (1954).
- Meiboom, S., and D. Gill,
"Modified spin-echo method for measuring nuclear relaxation times",
Rev. Sci. Inst., 29, 688-691 (1958).
- Simpson, J. H., and H. Y. Carr,
"Diffusion and nuclear spin relaxation in water", Phys. Rev.,111,
You must read the
on safety procedure in this laser manual before starting experiment.
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An important objective of this course is to instill habits of record
that will serve you well in future research. A good laboratory notebook
essential when you begin to write papers or to develop oral
summarizing your experimental efforts. A clear well-written narrative
includes experimental schematics, plots of raw data, and details of
analysis methods will enable you to receive quick feedback and
during lab sessions.
You will need a standard experimental notebook (as shown in class) in
dated record of procedures, events, original data, calculations and
of every experiment is to be kept. Although you will work in a group
are urged to collaborate on all aspects of the experiments, each
must keep a complete, dated record of each experiment and its analysis.
During your time in the lab, write down the procedures, experimental
parameters/conditions, problems encountered, and how you solved
them. Cataloging your experience in the lab is crucial for replication
of your experiment. Your lab notebook should be written such that in a
hypothetical future you or anyone else can replicate your work based on
the notes alone.
Your notebook will be checked during class times several times a
The following is a list of record keeping guidelines to follow when
Create a descriptive table of contents
make an entry every time you add new material.Title the table of
contents with the
Date - Contents - Page. Don't use generic entries like "Day 1" or
Instead, produce records of signifcant mile stones: e.g. "Calibration
NaI Scintillation Counter Using Ba-133 and Na-22 Check Sources",
- Don't erase, use white-out, or tear out
of a lab notebook. Indicate \mistakes" by simply drawing a single, neat
through the item. These may prove not so incorrect as initially
and will very often be useful as a guide to how the experiment was done
provide clues on how to better execute the experiment next time.
- Loose-leaf pages are not acceptable
a lab notebook. Graphics or tables generated by computer must be neatly
into the notebook. Remember to annotate these types of graphics with as
information about how they were created as possible.
- Your notebook should contain diagrams,
tables of raw data, formulas, computations, reduced data, error
and conclusions in a neat compact, orderly arrangement.
- Bring your notebook to every lab session.
to do so will result in penalties to your grade.
Notebook grading criteria
- Notes are original, in-class notes.
- Notes are easy to follow: an outsider could
recorded and why.
- Notes are complete: operations or conditions
interpretation or analysis of data are given.
- First page includes name of experiment, names
dates beginning and ending experiment.
Apparatus diagrams and annotations
- The diagrams + annotations clearly describe
works and how it was used.
- Diagrams are well annotated,
function of each important component, and important physical
features (e.g. magnet orientation, important dimensions).
- Raw data are correct: no significant mistakes
collection of data.
- The data set is sufficient to calculate all
results and uncertainties.
- Relevant conditions pertaining to data sets
sample type, run
number, equipment settings) are present.
- Tables of data include an estimate of
for assigning that uncertainty.
- Raw data are recorded neatly, with correct
units on the computer or directly into notebook. Computer data should
be pasted into the notebook.
Analysis and Results
- All classes of data taken have at least one set
analyzed. [All data
sets must be analyzed in final report.]
- Analysis of data has correct units.
- Plotting and fitting of data to obtain results
- All calculations are
- Graphs are easy to read:
estimate data points from the graph itself.
- Graphs follow these basic formatting
Legends are given
for graphs with multiple data sets and/or curves; data points are bare
point symbols not
with lines; when applicablepoints include error bars; theoretical
curves and/or fits are shown as
lines (not points); axes are labeled with correct units;
there is a clear caption
explaining the graph purpose.
- Spreadsheet printouts are clearly laid out with
rows, including quantities and units.
- For each of the four experimemts, after
completing data collection SEND
THE RAW DATA to the TA.
analysis and calculation
- <>Uncertainty is calculated for numerical
least one data
set in each class of data. [full calculation to be included in final
- Reasoning and method used to derive uncertainty
- Preparing for an
EATING OR DRINKING IN THE LAB
o Prior to each new experiment
read the experimental writeup
in order to understand the physics involved. Do not start an
experiment before understanding the entire procedure.
Each lab guide includes a set of preparatory
which point you to the essentials of the experiment. Work out the
to these problems in your lab book
the experiment. Make a copy of your solutions and hand to the TA
later than the beginning of the second session. Late solutions will not
accepted because you will need to know this material BEFORE the
objectives and procedures.
The next entry in your lab book
be a statement in your own words of the essential physics ideas and
of the experiment. List your experimental objectives and how they
to the essential physics. After listing the objectives, identify
things you will have to do, the data you must obtain and identify the
o Your laboratory notebook
should be with you
all times and used to keep a record of every step of the
It must contain sufficient narrative as the experiment proceeds so
years later, you could reproduce the results you obtained. Notes,
and graphs should be neat and compact, leaving as little empty space in
lab notebook as is compatible with clarity and the logic of
There should be no loose sheets or graphs in your notebook.
o On the first day of a new experiment, before turning
any of piece of equipment, read the manual
with the controls and operation. The relevant manuals will be
near each experiment. If you cannot find a manual ask the course
to help you find it.
o When you feel confident you understand the equipment and
measurement procedure hook up the experiment according to the
described in the lab writeup and turn on the the equipment.
o At this point sketch a block diagram of the apparatus and
chain in your lab notebook.
o Note typical â€œreadings" and instrumental
as to be able to quickly setup an experiment on subsequent days.
o Sketch waveforms at various places within the
chain. This will help ensure your understanding of each component and
you to rapidly identify equipment failure.
o When tabulating data into columns, use headings and list the
and estimated measurement uncertainties.
o Don't wait until after the session has ended to
examine the quality of your data. Create hand drawn plots of
as they are acquired, not later. These initial plots will save you time
frustration in making sure that your data are reasonable and suggestive
the behavior you expect. Analyze data in the lab in a preliminary way
you go along to check for reasonableness. If you are making a series of
of one quantity as you vary another, plot the results as you go along
that you can see the trend, catch blunders, and judge where you may
more or less data. Repeat every measurement at least five times
as independent a manner as possible in order to establish a statistical
for estimating random error and to reduce the chance of blunders. If
get through all the manipulations and preliminary analysis of an
in less than the alloted time, take the opportunity to perfect part or
of the experiment so as to obtain the best possible data set.
o Some experiments will require you to transfer your
to a computer and store them in files on disk. Obviously, it is not
in these cases to print out all your data and paste them into your
However, your lab notebook should include a clear description and
of the data files so that when you return to them days or weeks later,
are able to identify particular files with procedures you carried out
the lab. Identify the location of large data files or long analysis
if they are too big to directly enter or tape into your notebook.
scripts, functional forms for non-linear fits, etc. should always be
in your notebooks.
o Your notebook will be checked and graded
o As a courtesy to the next group leave your work area
least as tidy as you found
it. Return reference material and
at the end of each lab.
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We have several Windows 7
machines and one XP machine (muon experiment). They should have the
most recent version of Origin
be downloaded here
an example can be found here
python 2.7, 3.6 & Libre Office (spreadsheet, power point, and
word). There is also a general notes file which activates on start up
to put notes if needed. Old data will be systematically deleted when a
new group starts an experiment. BE AWARE OF THIS, OR YOU MAY LOSE YOUR
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References on Statistics
The lab report should show mastery of the entire experiment, and
a neat appearance with concise and correct English. Length should be ~
3200 words (excluding the title
bibliography and supplementary information in appendix ). This
to ~ 8 pages with double spacing and 12 pt font.
(If you wish, you may attach data sheets for your own records.)
if you chose PRL or Nature format it should be ~ 4 pages (two column
font and single spaced).
For publication style reports you may use a Word
For collaborating on a report in Latex you can also use overleaf.com
If using Latex you will need this
. To insert figures you will need figure files
as in this example
and for citations you will use a bibliography file as this
. To compile the file use Revtex 4.1
Also there exist collaborative Latex tools such as Write latex ( https://www.writelatex.com/
that allows a group to edit and compile a single document online
similar to google docs.
The report should consist of the
II. Introduction (purpose, equations; 1 ~ 2 paragraphs)
III. Apparatus (1 paragraph of description)
IV. Data (pages from the student's lab notebook)
V. Analysis and Results (graphs, calculations, answers)
VI. Discussion (measurement uncertainties) and Conclusions
ABSTRACT should appear on the title page. This is part of title page of
report, but it is a good idea to write it last, when you know exactly
you are summarizing. The abstract is a concise summary of what the
will find in the paper. It should briefly mention the motivation, the
and most important, the quantitative result with errors. Based on
a conclusion may be drawn. You should use appropriate technical
leaving their definitions and explanations for the Introduction.
INTRODUCTION OR BACKGROUND. Desctibe briefly what the experiment
about: Give some historical context, but not many pages or long
Outline theoretical results which will be needed, but omit intermediate
of derivations; you don't have to tell everything you know. Be sure to
all terms appearing in formulas. Material and ideas drawn from
work of others must be properly cited in the bibliography.
APPARATUS AND PROCEDURE. This section describes the main components of
apparatus. It makes reference to a figure(s) which contains a
of the apparatus and includes the most important signal processing
The figure should be referenced as early as possible in this section
the placement of the figure as close to the descriptive text as is
This should be followed by a description of the procedures and of the
DATA. Give a narrative, which cites data in tables and graphs. All
and tables should be numbered, and should have captions.
sure that axes are labeled, with units. The text should tie everything
in a linear sequence. Therefore all Tables, Figures, and Graphs should
cited by number at an appropriate place in the text. Place Figures,
and Tables in the text as close as possible to where they are cited
than at the end of the report). Do not inundate the reader with
you should find a way to summarize your results in two or three
ANALYSIS Compute from your data whatever quantities are most
for making comparison with theory, or for extracting useful
Where repetitive calculations are necessary, present one sample
to make the procedure clear. Be sure to include a precision (i.e., "error" analysis
), which starts from estimates
the uncertainties of the measured quantities and leads to an estimate
the precision in the final quantity derived [See any of the references
statistics and error analysis
crux of the report is how much you can get out of your measurements and
reliable the results are.
CONCLUSIONS. State the main results, but omit vague generalities. List
discuss possible causes of any discrepancies between your experiment
theory or previous measurements; bring your estimate of precision into
discussion. You might suggest specific improvements of the experiment.
BIBLIOGRAPHY. In this section which should be after the
page list all references used, whether explicitly cited in the text or
Use citations throughout the paper to acknowledge sources. These
may be by number or by author.
It may be useful to model your reports on Nature letters or
Review Letters (some copies are reserved in the lab).
Reports will be graded using the following criteria:
1. Theoretical and/or Experimental Motivation - 15%
2. Description of Experiment - 15%
3. Data presentation and Analysis - 40%
4. Conclusions and answers to questions 20%
5. Style and English - 10%
6. A 4% deduction will be assessed for EACH day the report is late.
on basic measurement apparatus
Prevention of injury is a
of being aware of pieces of equipment that are potentially
Since it is virtually impossible to set up a reasonably comprehensive
interesting set of experiments in modern physics without using
which has potential hazards, it is essential to be aware of the
and exercise appropriate precautions.
The first rule is never to work alone. All high voltage supplies are
marked as dangerous. Do not poke or probe into them. Turn off the
if you need to change cable connections. The supply may be dangerous
when turned off if the capacitors have not discharged; always keep one
in your pocket when testing any circuit in which there may be high
present so that if you get a shock, it will notbe across your chest.
go barefoot in the lab. Remember that it is current that kills. A good
sweaty) connection of 6 volts across your body can kill as well as a
connection of 600 or 6000 volts.
A laser beam may not seem very bright, but if it enters your eye it
be focused by the lens of your eye to a pinpoint spot on the retina
the intensity is sufficient to destroy retinal cells. It is wise to
a laser beam with a diffuse absorber so that the beam doesnâ€™t
the room. Never examine the performance of an optical system with a
by viewing the beam directly with your eye or reflector.
Radiation Safety - link to power point
Ionizing radiation damages tissue; any exposure should therefore be
minimized. The unit of radiation exposure is the rem (roentgen
equivalent man). Your inescapable dosage from cosmic rays and other
background sources is 360 mrem yr−1
, which works out to 4.2
recommended limit to controllable exposure for a member of the general
public is 100 mrem yr−1
, averaged over any consecutive five
years. If you follow the Lab guidelines, your exposure will be
only a small fraction of the dose you receive from the natural
Radioactive sources emit three types of radiation: high energy helium
nuclei (alpha rays), electrons (beta rays), or photons (gamma rays).
Most of the sources in the Modern Physics Lab emit only gamma
The strength of a radioactive source is measured in curies (Ci).
A one-curie source has an activity of 3.7 x 1010
The “absorbed dose” is a quantity that measures the total energy
absorbed per unit mass; it is measured in rads, where 1 rad = 100 erg
. The “equivalent dose” is measured in the units
the rem. The equivalent dose is derived from the absorbed dose by
multiplying by a “radiation weighting factor” which is a measure of how
damaging a particular type
of radiation is to biological tissue. For photons (gamma rays) and
electrons and positrons (beta particles), the radiation weighting
factor is unity; for helium nuclei
(alpha particles), it is 20; for protons with energy greater than 2 Mev
it is 5; and for neutrons it ranges from 5 to 20, depending on the
energy. When you use the meter in the lab, the readings are in rads,
and you must consider the type of particle when you work out the
For gamma rays with energy greater than 1 MeV, a useful approximation
is that the equivalent dose due to a source with an activity of C
microcuries is 5.2 x 10−4
where R is the distance from
the source in meters and E is the energy of the gamma ray in MeV.
For gamma rays with energy less than 1 MeV, this formula is still
approximately true for a full body dose. However, low-energy gamma rays
deposit their energy in a smaller mass of tissue than high-energy gamma
rays and can cause high local doses. For example, the local dose to the
hands from handling a 10 keV source can be up to 25 times the value
given by the above formula; hands, however, have a higher tolerance to
than inner organs or eyes.
The protective value of shielding varies drastically with the energy of
the photons. The intensity of a “soft” Xray beam of < 1 keV can be
reduced by many orders of magnitude with a millimeter of aluminum while
1.2 MeVgamma rays from 60Co are attenuated by only a factor of 2 by a
lead sheet one-half of an inch thick. The best way to keep your dosage
down is to put distance between you and the
source. If you stay a meter away from most sources in the Lab, you will
be receiving, even without any lead shielding, a dose which is much
less than your allowable background dose. If, however, you sit reading
the write-up with a box of sources a few inches away, you may
momentarily be receiving ten to a hundred times the background level.
Precautions for Working with Radioactive Materials - ALARA
1. Donâ€™t handle radioactive sources any more than you have to.
2. Work quickly when transferring or positioning radioactive sources.
3. Never take a source out of the Lab, even temporarily.
4. Keep sources away from your body.
5. Be aware of the sources being used in neighboring experiments.
6. Remember ALARA â€“ As Low as Reasonably Achievable!
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INSTRUCTIONS FOR ORAL
tutorial on writin
Powerpoint presentations can be downloaded
At the end of the term, each student will give a public oral presentation which will be attended by all students in the section. The presentations
be in the style of a paper presented at a conference. Questions
classmates are encouraged allowing for a general discussion of the
should be about your fourth experiment, unless a substitution is agreed
with the instructor.
should attend the whole session, and participate in asking questions.
partner will have 12-15 minutes to make a presentation, with a few
after each part for questions (such as requesting clarification). There
be time for questions addressed to either partner after their talks.
should decide between themselves how to divide the material
theory, apparatus, procedure, data, analysis, conclusions, etc.).
each should give a single segment.
should be prepared for a powerpoint
presentation. It should include title page, outline of talk, graphs,
summary of conclusions, etc.. Do not include
text or long derivations of equations, but just outlines, final
or a few sentences of conclusions. The blackboard is also available.
the talks with your lab partners. In addition to refining the
checking the length, and making sure nothing crucial falls through the
cracks, try to anticipate questions which
may be raised.
should ask at least two questions (overall) of other speakers (besides
partner). These should not be confrontational, but seek clarification
surprising, intriguing, or unclear points