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PHYS 432 A: Modern Physics Laboratory

Meeting Time: 
MW 1:30pm - 4:20pm
PAB B248
David Pengra

Syllabus Description:

Physics 432, Spring 2020


David B. Pengra
Office: Physics/Astronomy Building, Room B256A
Phone: 543-4783

Class Hours

Section A - Monday & Wednesday
Zoom lecture: 1:30 – 2:30 pm
Zoom work sessions: 2:00 - 4:00 pm
Section B - Tuesday & Thursday
Zoom lecture: 1:30 – 2:30 pm
Zoom work sessions: 2:00 - 4:00 pm

Required Reading Material

The course material will be primarily distributed from the course website, not handed out in class. You are expected to print out your own copies of the experiment instructions or otherwise have them available with you during the lab meetings.



No text required, but the following are recommended.

Experiments: Experiments in Modern Physics, Adrian C. Melissinos (Academic Press, San Diego, CA, 1966), and The Art of Experimental Physics, Daryl W. Preston and Eric R. Dietz (John Wiley & Sons, New York, 1991). 

Theory reference: Atomic Physics, C. J. Foot (Oxford University Press, Oxford, 2005).

Additional material is posted on the experiment pages and will be added during the term.


The modern physics labs in the 43x series are intended to provide a bridge between the introductory labs, which are mostly "canned" in the sense that there is a fixed sequence of activities to perform and a fairly rigid analysis to carry out, and the kind of "open ended" research that you would do in a real experiment, where you don't really know what will happen or how you should interpret the results. In addition, the physics itself is more complicated than in the intro labs. As a result, most of the experiments in this course require significantly more time for data analysis and uncertainty assessment than for data taking itself.

The experiments in 432 focus mainly on the physics of individual atoms or molecules. Most are forms of spectroscopy: the basic measurements probe the relationship between the variation of a particular parameter, such as wavelength or magnetic field, and the transition energies between various electronic states of an atom or molecule. The range of electromagnetic energy treated by these experiments runs from x-rays (keV) through visible light (eV), down through radio waves (neV). Although each energy range requires different detection techniques and apparatus, there are common threads that run through many of the experiments, for example, the physics of quantized angular momentum and the consequent ideas of selection rules and Zeeman energy appear again and again.

It is expected that students will work in groups of 2 or 3 to analyze data and draw conclusions which will be recorded in a graded group notebook.  Each student will also write a separate short written report.  The grade is entirely based on the work turned in and on a record of participation with partners and communication with the instructor.

Special Note: Because the lab course will be conducted remotely, for the first time ever, course requirements, deadlines, and expected work and participation will likely change during the term. This syllabus should be regarded as an evolving plan, not a contract.

Basic requirements

Required work:

  1. Complete six experiments, which means produce 6 group notebooks on OneNote or Google Docs and write 6 personal reports.
  2. Participate in weekly Zoom discussions with instructor(s) and partners.

Each of these requirements is discussed further below.


  • Experimental groups must be no larger than three persons. With four persons or more, there is not enough to do to keep everyone busy.
  • Each student must write their own Personal Report. Students work together on experiment description, data reduction and analysis. They are encouraged to discuss their conclusions and results with each other (and with students outside their group) but each person must independently produce their own written reports.
  • You should have at least one partner. Most students learn more by talking with other students than they would by working alone.
  • Only if and when University restrictions on in-person instruction are lifted may a student or group of students enter the physical lab space in the Physics/Astronomy Building.


At the nominal class time of 1:30pm Pacific Time, a Zoom lecture will be presented during most class days (Monday, Wednesday for section A; Tuesday, Thursday for section B).  The lectures will discuss the essential physics of the experiments, and related theory in atomic physics with an emphasis on the experimental aspects.  The lectures will be recorded and posted for later review, along with the lecture slides.

Students registered for one section may participate in the Zoom meetings of another session if they wish.  The Zoom sessions will be the best place to get your questions about atomic physics answered.

Experiment videos

For each experiment, a video will be produced that shows the experiment in detail: what the apparatus is, how it is assembled, how the electronics are configured and connected together, and any other important physical detail you would need to know in order to operate it. The videos will also show how data are collected, plus other measurements needed for calibration or analysis.

You will be expected to watch the videos and take notes, in particular, you will want to sketch out diagram(s)  (1 or more) of the setup to include in your notebook (see below).  Questions about the apparatus will be posed by the instructor which you should also discuss.

Working Groups & Meetings

Students in each section will self select into working groups of 2-3 persons each.  To choose your group, go to People via the navigation sidebar and then select the "Groups" tab.  Each group will have a collaboration space in which to keep files, links to notebooks, and discussion boards that are private to the group.

The groups must agree on a time for their working meetings.  Optimally, these meetings should take place during the scheduled lab days, between 2:00 - 4:30 pm, however other times are acceptable.  Group meetings may occur on Zoom (preferred), other video conferencing apps like Skype or Google Hangouts, or through discussion boards or chat (for those with time conflicts or low internet bandwidth).  Regardless of the mode of meeting, it must be arranged with the instructor or TAs so that they may also participate and be able to ask and answer questions of the group.

Participation credit will be assessed for each student for each scheduled class day.  For full credit, each student must communicate in a substantial way with the group members and instructor/TA concerning the lab material. This may happen as a matter of course in an online conference, or asynchronously via a discussion board associated with the current lab.

In either mode of Working Meeting — live synchronous meeting or asynchronous chat/message board — each group must adopt an agreed-upon meeting time to check in with each other and discuss or present information to be assessed.

Meeting participation credit will count for 30% of the final grade.

Group Notebooks

Graded written material will consist of (1) group notebooks, created and graded in an online group space (see below) and (2) separate individual short reports, uploaded as PDFs directly to Canvas. 

The group notebooks may be created in Microsoft OneNote or in Google Docs through the Collaborations feature. However your group chooses to build your notebooks, you must do the following:

  1. Make sure that the instructors and TAs have access.  The online notebooks will be checked after the end of each class period to assess progress. This access is ensured if you use the Collaborations feature or the specific OneNote notebook created for the course.
  2. Include everything you do concerning the lab into the notebook.  The notebook is a working document.  It is NOT a report. If you work out some things on paper, or in your own online space, you must put copies of these materials into the group notebook.  If you write a separate computer file, such as a spreadsheet or computer program, you must add a link to or a copy of these.  Any one person in the group, including the instructor or TA should be able to see everything that all members have contributed.  This is the way scientific records are treated.

Information on how to get started with either OneNote or Google Docs through Collaborations is available at the page Getting started with Group Notebooks.

Group Notebooks will count for 35% of the final grade.

Individual Reports

Each student must also write and submit their own individual report, as a PDF uploaded to a Canvas assignment.  The structure and content of the report will be described in the assignment, and will vary as the course proceeds, but there are a few common aspects:

  • It must conform to strict formatting rules and length limits.  Typically,  a report must be between 2 and 4 pages, be typed, use 11 or 12 point font and 1 inch margins. 
  • It must be written well, with complete grammatically correct sentences and structured paragraphs.
  • It must address certain questions or topics in a certain order.  For example, the first paragraph should state the experimental measurement done, the method of the measurement or experimental technique, and the main quantitative result.  Later paragraphs should answer specific questions requested in assignment.

More information is given in the page About Individual Reports.

Individual Reports will count for 35% of the final grade.


Due to the online nature of the course, and the fact that videos of the apparatus must be produced as the term goes on, all groups will work on the same experiment at the same time, up through the first four experiments, which are fundamental to the development of atomic physics.  Then, groups will have the option of finishing with two experiments along one of two paths.  Path 1 focuses on magnetic interactions involving the nucleus.  The pulsed NMR and Optical pumping experiments show how nuclear magnetic moments can be related to RF absorption, and can be understood through the model of a Bloch sphere.  Path 2 illustrates two different methods used to measure the energy states of atoms in ways that circumvent the limitations arising from the motion of the atoms themselves: the Doppler effect.

First 4 Path 1 Path 2
1: Hydrogen-deuterium mass difference 5: Rubidium optical pumping 5: The Hanle effect
2: X-ray fluorescence 6: Pulsed NMR 6: The Lamb shift in hydrogen
3: The Franck-Hertz experiment
4: The Zeeman effect in mercury


Group Notebooks

Notebook grading will reflect "real-world" assessments: the kinds of assessments that are typical in work environments and active research.  Notebook assessments will be listed as letter grades A, B, C, D, F which correspond to numerical grades 4, 3, 2, 1, 0, and are based on the typical workplace assessments outstanding, exceeds expectations, satisfactory, below satisfactory, nothing to assess

The Group Notebook will be worth 35% of the experiment grade and the same letter grade will be assigned to all students in the group, subject to participation adjustment (see below).  The notebooks will be graded ASAP after the due date.  There is nothing to "submit:" whatever is in the notebooks will be graded. There are no extensions to these due dates unless a special arrangement is made before the due date.  Comments from the instructors may appear before the due date as reminders for things to fix or clarify by the members of the group, but no grade will be assigned until after the due date has passed.

Participation and Group Notebook grade adjustment

It is expected that all students in a group will contribute substantially to the Group Notebook.  Groups should designate aspects of the analysis or tasks to each member and hold all members accountable for their contribution. Who is responsible for what should be stated clearly within the notebook.  If a student fails to complete an assigned task, this fact will be noted by the TA/instructor who grades the notebook.  This participation assessment is used to adjust the student's score for the group notebook. 

Individual Reports

The Individual Report will count for 35% of the experiment grade, and it will be graded on a 3 level scale, corresponding to typical decisions made by scientific journals: accepted (A), accepted with revisions (AwR), and rejected (R).  These will correspond to letter/numeric grades of A/4.0, B/3.0, and F/0.0.  Reports that earn AwR or R may be resubmitted once.  Once a personal report may no longer be resubmitted, the final grade for it will be on the above A-F scale.

Working Meeting Participation

Credit for participation in the group's Working Meeting will be assessed on each scheduled day. The participation credit will also follow a "real-world" standard: A = Fully and frequently contributes to the discussion; B = Present and offers a few relevant comments; C = Present but comments or contribution minimal; F = Absent. 

It is important that the group participants communicate with each other.  It is not sufficient for a given student to simply write to the instructor with questions or only talk with the instructor during the meeting.  The TAs and the instructor will assess the communication mainly among the members of the group.

For groups working via live meetings on Zoom or other audio chat, the assessments should take about 15 minutes per group.  For this part of the meeting, students should prepare what they wish to discuss, for example, questions about an analysis task, a report on what they have accomplished since the last meeting, plans or ideas they may have for their assigned tasks, etc.  It is expected that the live meetings themselves may not last the full class period, and that the groups may very well meet online at times outside of the scheduled class times.

For groups that prefer to work asynchronously, the assessment will be based on the written record in a chat session or discussion board.  As in the live meeting, each group member should post on what they have accomplished, what they are working on, and any questions they would like answered, either by other members or on behalf of the group to the instructor or TAs.

Minimum requirements & Final Grade

Six (6) experiments are required. For an individual student, failure to complete at least three (3) Individual Reports with a score above zero will result in failure (0.0) of the course.

Group Notebooks and Individual Reports are due by the dates listed on the main page.  If you believe that you and/or your group needs an extension on grading, you must ask for it before the due date has passed.  Any exceptions to this rule must be granted by the course instructor.   Another due date will be negotiated for the work in question.

Grade Calculation

Assuming the minimum requirements have been met, the final grade will be calculated according to the formula

Grade =
Percent score
× 4.2

Thus, to earn a 4.0, you need about 95%.

Writing ("W") Option

A writing "W" credit will be awarded to any student who earns at least 4 "Accept" grades on their Individual Reports.

Catalog Description: 
Measurement in modern atomic, molecular, and solid-state physics. Prerequisite: PHYS 225; PHYS 334. Offered: Sp.
GE Requirements: 
Natural Sciences (NSc)
Section Type: 
Last updated: 
March 19, 2020 - 9:31pm