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PHYS 457 Experimental Physics (1- or 2-credit)
PHYS 457W Experimental Physics (3-credit)

Section 001 | Section 002

Fall 2009:   MW 10:10A - 1:10P, 309 and 310 OSMOND

 

Instructor: Qi (Jenny) Li

Email: qil1@psu.edu
Telephone: 3-5347
Office: 317 Davey Lab.
Office Hours: By appointment

Teaching Assistant: James Healy

Email: jch302@psu.edu
Telephone:
Office: S5 Osmond
Office Hours: By appointment

Textbook:

No textbook is assigned for this course

No textbook is assigned for this course.
Short introductions to each experiment, including links to documentations of most instrument to be used, can be found below.

Students are also encouraged to use resources available in libraries or online on the background of each experiment

Course Outline:

• Purpose of the course

To provide a general introduction to experimental techniques and instrumentation used in modern physics research labs.
To train students to work independently and creatively. While the instructor and the teaching assistants will be available to help, the students should try to work on their own as much as possible.

No formal lectures will be given in this class.

• Organization

Students will do experiments in teams of two.

Students taking course in the 3-credit option will do 3 short and 1 long experiments. Those taking the course in the 2-credit option will do 4 short experiments.

For short experiments, each team is required to choose one experiment from each of the three categories (see below). Students with the 2-credit option can choose the last short experiment in any category.

• Lab reports

The lab report is an important component of the course. You need to devote significant effort in writing good lab reports.

While the data will be shared by two team members, each student will write his/her own lab report.

For students with 3-credit option your lab reports for short experiments will be read by the instructor and may be returned to you with suggestions for revision. You will make changes and turn the report in again. Sometimes the report will be returned to you one more time for additional revision. No revisions will be required for students with 2-credit option.

For the long experiment, you’re required to turn in an informal preliminary lab report on the date as indicated below. The preliminary lab report should include the introduction and the theory sections, and the results you have (You should get most data by then already. No revision of the long report will be required.

• End-of-Semester Presentation

There will be a presentation at the end of the semester for all students. .

PHYS 457W (3 credit) students will present the long experiment as a team using Power-point.

PHYS 457 (2 credit) students will each present a short experiment.

Grading:

PHYS 457W (3-credit): 16% for each short experiment and 32% for the long experiment (half for experiment, half for lab report), 10% for presentation, and 10% for overall performance.

PHYS 457 (2-credit): 20% for each short experiment (half for experiment, half for lab report), 10% for presentation, and 10% for overall performance.

Factors for grading the experiment and lab report:

Experiment:

1) Motivation and persistence.
2) Completeness of the measurements.
3) Correctness of the data.
4) Understanding of the physics including the possible sources of error.

Report:

1) Correctness in physical concept.
2) Compliance to the format of the report as described below.
3) Clarity and style.
4) Completeness, especially in error analysis.

The presentation will be graded mainly on the clarity, general performance, and understanding of the experiment.
The overall performance will be evaluated based on the quality of your work, initiatives, and participation.

There will be no exams for this class.

• Error Analysis

The experimental error is the deviation of your measurement from the true value of the quantity, a number that can be estimated in a scientific way. It is NOT the same as the difference between your measurement and the accepted value of what you are trying to measure (which, unfortunately, is commonly assumed), even though the accepted value is presumably close to the true value. For the purpose of this course, this distinction means that we usually do NOT obtain the experimental error by simply comparing the result of our measurements with the accepted value.

A more detailed discussion on error analysis is posted on the course website.

The error analysis is very important for scientific research as it helps us understand nature of the measurement, and ultimately, how much you can trust your result. To track down all sources of error and come up ways to eliminate them when possible are an intellectually challenging task.

Your final result for quantity X should be written as (X ± delta(X)) followed by the unit of the quantity, where delta(X) is the estimated error of X.

• Instructions for writing lab report (Very Important!)

1. The lab report should include the following sections:

• Title, your name and your lab partner’s name, and the version of the report for PHYS 457W students.

• Abstract. Summarize the purpose, method, and the main results of the experiment.

• Introduction. What? Why? How? Big picture stuff!

• Theoretical and other background information.

• Experimental method(s). Schematics of the experimental setup is required.

• Experimental results. Include raw data in an appropriate form and analysis of the data.

• Evaluation of experimental uncertainties. For a discussion on error analysis, Click Here.

• Discussion and conclusion. Indicate the main implications of the experimental results.

• References. Cite the most relevant ones. Elementary things from common textbooks are not necessary to reference. Follow American Physical Society (APS) style when citing a reference.

2. The lab report should be limited to 5-6 pages for short experiments and 10-15 pages for long experiments, excluding illustrating figures and plots of experimental results.

3. Use 12-point fonts and 1.5-line spacing for your reports.

4. Each figure should include a figure caption, placed below the figure. If you use tables, each table should have a table caption, placed above the table.

5. Writing styles should follow American Physical Society (APS) style handbook, available online at

http://publish.aps.org/STYLE/

7. Lab reports should be turned in hard copy (single sided if possible).

• Instructions for presentation

1. Format: informal.

2. Each presentation group will have 10 minutes for presentation and 2 minutes for questions and answers.

3. Contents: consistent with the lab report.

4. Power-point or equivalent format. We will provide one computer for the presentation. Please bring your file to the TA to preload your presentation

Important Notice:

The University regulations on radioactive substance require that absolutely no food or drinks be allowed in Room 310. A failure of observing this rule will automatically result in an “F” grade for this course.

Calendar:

1

9/2

Introduction and organization.
1st short experiment.

2

9/9

1st short experiment.

3

9/14 & 9/16

1st short experiment.

4

9/21 & 9/23

2nd short experiment..
Lab report for the 1st experiment due Monday, 9/21.

5

9/28 & 9/30

2nd short experiment.

6

10/5 & 10/7

3rd short experiment.
Lab report for the 2nd experiment due on Monday, 10/5.

7

10/12 & 10/14

3rd short experiment.

8

10/19 & 10/21

long experiment.
Lab report for 3rd experiment due on Monday, 10/19.

9

10/26 & 10/28

long experiment.

10

11/2& 11/4


long experiment.

11

11/9 & 11/11

long experiment.

12

11/16 & 11/18

Long experiment.
The preliminary long report and the 4th short report for 2-credit student are due on 11/16

13

11/23 & 11/25

Thanksgiving break.

14

11/30 & 12/2

Finish the Long experiment.

15

12/7 & 12/9

Presentations.
Presentation in electronic format is due on Monday morning.

16

12/15 & 12/17

Finals Week.
Class will not meet

 

Experiments:

 

Fundamental Constants:

Speed of Light
The velocity of light is one of the most important and intriguing constants of nature. Whether the light comes from a laser on a desk top or from a distant star, the speed of light is constant. The speed of light is also important for other reasons. It establishes an upper limit to the speed of any object, according to Einstein’s special theory of relativity, and objects moving near the speed of light follow physical laws which are drastically different from Newton’s laws. Some of the most accurate early measurements of the speed of light were those made by Albert Michelson between 1926 and 1929, using methods similar to those employed here.
Current Balance
The current balance is used to measure the force of repulsion between identical oppositely directed currents in parallel conductors. The magnitude of this force can be shown using classical electrodynamic theory to be , where I is the current in either conductor, L is the length of the conductors, r is their separation and m 0 is the magnetic permeability of free space.
Cavendish Experiment
In 1665, Isaac Newton proposed that all bodies attract each other, according to his famous law: F = G m1m2 / r2 , where G is the gravitational constant, m1 and m2 are the masses of the two bodies and r is the distance that separates their centers of mass. In 1798, Henry Cavendish constructed a device to measure G, using a torsional balance and masses. In this experiment, we will use the method of Cavendish to measure G.
Millikan Oil Drop Experiment
The electric charge carried by any object such as an elementary particle cannot take arbitrary values, but in fact is quantized: it can take on only an integer multiple of a fundamental value e = 1.602 ´ 10-19 C . This fact was first discovered experimentally by Robert Millikan in 1909, using an apparatus of his devising conceptually very similar to the one you will use in this experiment. His technique utilizes tiny oil droplets …
Coulomb Balance
In 1785, Charles Augustin de Coulomb discovered that the electrical force between two point charges varies inversely with the square of the distance between them, which is known as the Coulomb's Law. The constant of proportionality, k, is the Coulomb constant. In this experiment, you will use the Coulomb balance to measure the Coulomb Constant k.

Resonance and Interference:

This experiment is designed to study a simple mechanical system: a string fixed at both ends. This system has a set of natural frequencies, at which standing waves are formed. If the string is driven by an external source with some frequency, the string will experience the strongest vibrations if this frequency is equal to one of the natural frequencies of the system.
Harmonic oscillators play a very important role in physics, and so it is necessary that you understand them well. In this experiment, you will be able to explore damped and driven harmonic motion with the Driven Harmonic Motion Analyzer (DHMA). The analyzer displays the frequency at which it is driving the mass-spring system and measures the amplitude and period of the oscillations. The operation and setup procedures are described in detail in the manual. Be sure to follow the setup procedures carefully before performing each of these experiments.
Microwaves have wavelengths of the order of centimeters, which allows them to be used to do "macroscopic diffraction" experiments. This is instructive because one can readily see the crystal structure which is diffracting. The diffraction theory is, of course, identical to the Bragg theory which applies to electron and X-ray diffraction.
A free electron has spin ½, which means the stationary states in an applied magnetic field have components of spin angular momentum parallel to the field of ± ?/2 . There is a corresponding magnetic moment µ= ± ½ gµB, …

Others:

X-ray Diffraction
When electromagnetic radiation is incident upon a periodic array of scattering centers, there are certain discrete directions for the incident ray that result in strong reflections. This is because of constructive interference of the radiation scattered from each of the centers. The directions for which these strong reflections occur are related through the Bragg law to the geometry of the arrangement. Therefore, measurements of the angles and intensities of the Bragg reflections can be used to deduce the arrangement and spacings of the scatterers.
Franck-Hertz Experiment
The Franck-Hertz experiment verifies that the atomic electron energy states are quantized by observing maxima and minima in transmission of electrons through mercury vapor. The variation in electron current is caused by inelastic electron scattering that excites the atomic electrons of mercury. The 1925 Nobel prize in physics was awarded jointly to Franck and Hertz for their discovery of the laws governing the impact of an electron on an atom.
High TC Superconductors
High-temperature superconductors exhibit superconducting behavior, e.g., the Meissner effect, zero resistance, etc., at temperatures which can be attained using liquid nitrogen. Below the critical temperature, the superconducting state may be destroyed by applying a large enough current or magnetic field. This occurs at the critical current density or the critical magnetic field, respectively.
Granular Matter
In the past decade or so granular materials have become a fast growing field of research in physics. Granular materials capture the attention of physicists because they pose novel questions of fundamental interest, and are of interest for certain practical applications, such as transport and storage of powders in mining industries, food and pharmaceutical productions, and soil and sand management.

Long Experiment:

Compton Scattering
In 1923 Compton discovered that when a beam of x-rays of well-defined wavelength is scattered through an angle by sending the radiation through a metallic foil, the scattered radiation contains a component of a well-defined wavelength which is longer than the original wavelength. This phenomenon is called the Compton effect.
Scanning Tunneling Microscopy (STM)
observe atomic images of surfaces and charge density waves. See R. Serway, Physics for Scientists and Engineers, with Modern Physics, 3rd ed. (Sanders, Philadelphia, 1990). 
Mössbauer Effect
measuring changes in the nuclear spectrum of 57Fe in different materials to determine the local magnetic and electronic environment. See G. Wertheim, Mössbauer Effect: Principles and Applications (Academic Press, New York, 1964) or D. P. E. Dickson & R. J. Berry, Mössbauer Spectroscopy (Cambridge U. Press, New York, 1986). 
Raman Effect
measure excitation spectra of molecules by using inelastic light scattering. See S. Walker & H. Straw, Spectroscopy, vol. 2 (Chapman & Hall, London, 1962) or P. J. Hendra & T.R. Gilson, Laser Raman Spectroscopy (Wiley, London, 1970). 
Muon Lifetime
measure speed of cosmic-ray muons and infer relativistic effects; measure the lifetime of muons decaying at rest. See MIT Speed and Mean Life of Cosmic Ray Muons lab manual, available at: http://web.mit.edu/afs/athena.mit.edu/course/8/8.13/JLExperiments/JLExp_14.html
Hall Effect
determine the properties of charge carriers and the band gap in semiconductors. See Preston & Dietz, Chapter 17. 
Nuclear Magnetic Resonance (NMR)
Nuclear Magnetic Resonance (NMR) is a phenomenon which involves the magnetic moment of nuclei processing about a static magnetic field. If this nuclear spin system is exposed to a second oscillating magnetic field at the processing frequency, we can observe a resonance in the coupling. In this experiment, we use RF pulse sequences to probe NMR. We can prepare spins in a certain orientation and watch them relax to random orientation. NMR is a fundamental example of a resonance phenomenon and is also a technologically important tool, such as in medicine NMR imaging of diseased tissue.
Electron Spin Resonance (ESR)
Instead of probing the spin resonance phenomenon with nuclear spins in an external field, electron spin resonance (ESR) involves the resonance of the unpaired electron spin states. Because the electron spin moment is much larger than the nuclear magnetic spin moment, we have to use larger frequency microwaves to excite the resonance in an external laboratory magnetic field.