Swain West 207/IUCF 144
856-4320/855-3057
email:rtayloe@indiana.edu
Office Hours:
W: 1:00-3:30pm and by appointment
- P301 (Modern Physics, or equivalent) and
- P309 (Modern Physics Lab, or equivalent)
- Recommended: P453 (Quantum Mechanics).
In this class you will learn advanced laboratory techniques and methods while investigating topics in modern physics, i.e. phenomena discovered in the last 100 years that exhibit the quantum-mechanical nature of the universe. You will become acquainted with methods and equipment used in the research lab and will practice with these while learning how to solve the problems that arise. You will learn how to analyze the resulting data (with errors!) and how to present your conclusions.
These are not "cookbook" labs. You will be given writeups with an assignment, but the tasks will be similar to a situation that you may encounter in a graduate school or industrial research project. A quantity or effect will be identified and your goal will be to measure or investigate it. Not everything will be spelled out. Your job will be to learn how to effectively and efficiently make a quantifiable statement about nature. This is ultimately the goal of the experimental physicist.
An (incomplete) list of skills that you will learn/practice/master are:
- Advanced experimental techniques and equipment,
- Problem solving,
- Data and error analysis,
- How to write an experimental report,
- Presentation of results.
Many of the experiments that we will do are explained in more depth in this text and it contains much good reference material.
In addition, a logbook is required. Obtain a type #43-64x (or equivalent).
Here is list of useful text and reference books .
We have approximately 12 experimental stations in the Modern Physics Lab. You will complete 4 of these experiments (as individuals) and write a report on each one. For the last experiment, you will be expected to take it farther by investigating some aspect of your own choosing. You will present a talk on this work during the final class period. In addition, during the first month of class there will be a few lectures and home work assignments. See the Experiments Page for more info on the experiments available.
You are required to come to class every Thursday that our class meets. The instructor will be available in the lab during office hours - you may work on the lab and get additional assistance during that time. Also, you will be given a key to the lab so that you can work on you own as needed.
This lab will become chaotic and not conducive to good science, if we don't all do our part to keep it neat, organized, and functioning. You will be required to:
- Always leave an experiment in a state working as good or better than when you started.
- Keep the lab clean and organized, e.g. tools put away, broken equipment identified, etc.
When we finish the semester, with your help, the lab will be in much better shape than when we started. That is an important skill to learn as well. Part of your lab grade will be based on these items.
You are required to prepare thoroughly for every new experiment that you begin. These experiments are not trivial and take some time to understand and setup. You need to read the experimental writeup and references before coming to class to start the lab. Lack of preparation will be discouraged vigorously.
There are several potential safety hazards in this laboratory, primarily involving high voltages or radioactive sources. You will be instructed on safe handling procedures and the use of monitoring equipment. A copy of the University Radiation Safety Regulations is also kept in the laboratory for your reference. Please look it over. The most important safety rule is think about what you are doing. Always be conscious of the hazards around you. Think before you act.
The small radioactive sources that we will use should be handled in such a way as to minimize exposure. Your level of exposure is proportional to the time that you handle the source, and is inversely proportional to the square of the distance from the source. So we will minimize the exposure time, maximize the distance, and use shielding as much as possible. After use, radioactive sources should be returned to the instructor for storage. They are not to leave the lab. Two items are sufficiently `hot' that they can be used only under the direct supervision of the instructor: the Neutron Beam Irradiation Facility, and the Co-57 Mössbauer source. Because radioactive sources may be in use, eating and drinking are not allowed in the lab.
The photomultiplier tube power supplies can generate fairly high voltages (~1000-1500 V). Though these supplies are current limited, they can produce a nasty shock if mis-handled. Just to be safe, never work alone around apparatus using high voltage.
There are also power supplies used for many of the experiments. Be careful working with these. Observe the one-hand rule.
One of the most difficult things to learn, yet one of the most important for future success in physics research, is mastering the "art" of maintaining a proper log book. You should keep a detailed log of all your activities in the lab. Because this is so important, I will require that you adhere to the following "Log Book Rules":
- Use a bound notebook (type #43-648 or equivalent) , not loose sheets of paper. Do not get the type with extra pages for carbon copies. Extra material, such as computer printout, photographs, etc., may be pasted or taped into the book.
- Make sure your logbook has numbered pages.
- Skip the first page or two to use for a Table of Contents.
- Start a new page for each experiment, but otherwise do not leave blank pages. If you have work to add from a previous experiment, just indicate this with a brief note ("Continued on page 57").
- Date every page, and record the time of the day for each important entry.
- Always write directly into your log; NEVER work on loose scraps of paper, and then copy things into the book. Even `mistakes' often turn out to be important!
- For the same reason, do not use pencil. If you discover that something was wrong, "X" it out so that it is clearly marked as being in error, but is still legible. Never use White-out, paste over, or (worst of all) remove pages!
As far as deciding what should be entered into your log book, this is largely a matter of personal taste. A few general guidelines might be:
- When you start a measurement, state briefly what its goal is -- just a few key phrases to remind yourself exactly what you will be trying to do.
- As you go along, jot down enough information to indicate what you are doing at that moment. Remember to note the times.
- Provide diagrams (sketches, electronic schematics) of the apparatus, with complete information on settings of controls and other relevant instrumental data. As a rule of thumb, these should be sufficiently detailed that you (or someone else) would have no trouble reproducing your experimental setup.
- All measurements should be recorded immediately and directly. Any necessary arithmetic (to convert your numbers to other units, to average two numbers, etc.) should be done in a second step, and also recorded. Remember to record the units for dimensioned quantities, and always estimate the uncertainties in any measured quantity.
- Any time your measurements result in a list of numbers (e.g., determining how a quantity y depends on the setting of x), you should immediately convert this information into a graph. This will not only often provide some `intuition' about their correlation, but will usually allow you to spot quickly any departure from a smooth dependence, which might indicate a problem with the equipment or an error in that single measurement.
- As soon as you finish collecting the data, present some preliminary conclusions: what worked, what didn't, and what else will need to be done to complete the analysis.
Your logbook will be handed in for grading a few times during the semester.
These reports should concentrate on the analysis of the data and the results. They may be terse yet should not lack critical details. A common mistake in student reports is to be overly verbose during the description of the experiment yet omit crucial details in the analysis and results.
See this sample report for more details.
We currently have several computers for the Modern Physics Lab. Several are used for data acquisition and one for data analysis and miscellaneous. These may all be used for data analysis and plots, however, do not over use them. Try to do an experiment completely before using the computer to make final plots. It is easy to get caught up in learning how to make this or that plot just right, when it could be done by hand, in your logbook, much more quickly and efficiently.
We'll use Visual C++ for data acquisition, Excel, Sigma Plot, and PAW for data analysis (and perhaps a few other tools later). Remember to keep your use of computers to a minimum. An important skill to learn is how to efficiently do experiments - sometimes computers spoil that.
- Logbook and assigned exercises (25% of your score)
- Experimental Reports (40%)
- Performance in the lab (25%)
- Final presentation (10%)