A. Choice of Experiment
All students are to complete two experiments. Some experiments are challenging while others are more routine. Typically, the first experiment is the more difficult because of lack of familiarity with the available equipment and procedures. The first experiment is good preparation for the second experiment. The experiments are flexible by design and allow students considerable latitude. Operation manuals for all the laboratory equipment are available in the laboratory.
Each student will discuss with the instructor the experiment he/she has chosen to perform. The purpose of the discussion is to identify appropriate measurement goals and provide the opportunity to ask questions and receive advice on how to get started. The papers referenced in the Graduate Laboratory Handbook are an important source of information about the experiments.
A written schedule for performing the chosen experiment and preparing the report will be established by each student in consultation with the instructor. The schedule should take into account the time necessary for deciding on the equipment that is needed, assembling and setting up the equipment, testing and calibrating the equipment and acquiring and analyzing, and interpreting the data. The schedule should take into consideration the physical foundation of the experiment, the available equipment, and experimental uncertainties. An estimate of the accuracy and precision of the expected results should be made. Familiarity with the equipment is useful in making a realistic schedule. Sufficient time should be allotted for the preparation of the report. While report conclusions cannot be written before the experiment is finished and the data analysis complete, much of the other sections can be written during the course of the experiment. In this way the report can be finished on time without the need for heroic last minute efforts. During the course of the experiment, it may be necessary to modify the schedule to take into account unanticipated events. This is usual and contingency time should be built into the schedule.
1. Performing the Experiment
Most time will be spent getting familiar with the experiment, setting up apparatus, and testing and calibrating equipment.
Taking data once the apparatus is operating correctly is generally the easiest and fastest part of the experimental work. Analysis of preliminary data should be done as soon as possible in order to make informed decisions on parameter choices or changes for successive data collection. It is essential to demonstrate and explain the working experiment to the instructor. Experiments should be performed with the goal of obtaining the best possible results, subject to the constraints of time and equipment.
There will be weekly individual discussions with the instructor. These discussions help to focus efforts and provide advice when there are questions and difficulties.
3. Experiment Demonstration
Near the end of each experiment, each student will demonstrate the operation of the experiment to the instructor and teaching assistant. This presentation should last between 15 and 20 minutes and should include demonstration of the signals that are being measured, where possible.
C. Laboratory Reports
Separate written laboratory reports for each experiment will be due at the end of each experiment as noted in the schedule for the course. These reports should contain a description of procedures, tables and graphs showing results, and a discussion explaining the results. Unless prior arrangements are made with the staff, late reports will be subject to a penalty of 1/2 point (out of a maximum grade of 12 points) per day late. Stylistic and formatting guidelines for writing the report are detailed in the introductory section of the Graduate Laboratory Handbook. The laboratory reports should consist of four sections; Introduction, Experimental Procedure, Results, and Discussion and Conclusions.
The Introduction should contain a clear statement of the purpose of the experiment. Relevant theory should be included in this section. Detailed derivations are not necessary.
The Experimental Procedure should contain all the information required to reproduce the experiment as it was done in the laboratory. A list of components and equipment along with schematic diagrams should be part of this section. The measurement procedures should be clearly described and the choice of parameters on various instruments justified.
The experimental data form the Results section. Effective presentation of data is an essential skill for scientists. Data are routinely presented in tables and graphs. When tables are used, columns should be clearly labeled with units. Graphs should have both axes clearly labeled. Each figure or table should have a descriptive caption. It should be possible to look at a figure and discern its meaning without reading the body of the text. Do not substitute a screen dump for a figure. Experimental data should be presented with estimates of errors or uncertainties. The errors can be systematic as well as random and can be due to limitations of the measuring instruments as well as uncertainties in the values of the experimental components. Temperature effects can cause the results to deviate from the expected values. A discussion of the errors should accompany the data. It is not necessary to include component specification sheets, but reference to them should be given where appropriate.
The Discussion and Conclusions section should contain comparisons between the predicted and measured properties of the system under investigation. Conclusions should be based on comparisons of the data with calculations based on the theory of the phenomena investigated. Suggestions for improving the experiment and applications of the results can be included in this section. Clarity rather than length or complexity is the goal of the reports. It should be possible to reproduce your results from the information in the report.
Scientific publications are most often subject to peer review, therefore each student will review the report of a fellow student and is encouraged to make constructive comments that address both content and style of the report. Students have the opportunity to incorporate changes in their manuscript before handing it in.
Each of the four sections of the report will be graded on a scale from 0 to 3 where a grade of 3 means that the section fully met the criteria listed above, and a grade of 0 means that none of the criteria were met. The maximum grade for a report is 12. It is essential for the report to be well organized, neat, clear, complete and with no misspellings nor errors in syntax.
D. Laboratory Notebook
Each student must have a bound laboratory notebook in which all data and descriptive information about each experiment are recorded. The notebook is the detailed record of the experiment. Learning to keep a research notebook is an important skill and is essential for experimental work. Notes and calculations on separate pieces of paper are not permitted. The notebook should be a "Computation Book" with large 9 1/2" x 11 5/8" numbered quadrille pages or equivalent. Similar looking laboratory notebooks with white and yellow pages that tear out easily are not to be used. The laboratory notebook must have a Table of Contents in the first pages to aid in locating the different experiments and the important parts of each of the experiments. It should be possible to reconstruct the experiment from the information in the laboratory notebook. All entries in the notebook are to be dated and made with pen, not pencil. Errors should be crossed out with a single line rather than erased or obliterated. Often an incorrect calculation or measurement will contain information that is useful later on. The notebook entries should include, but not be limited to experiment design, preliminary calculations, estimates of uncertainties, description and characteristics of the instruments, calibration data, procedures, preliminary data, and final data as well as details on data analysis. The information in the notebook should allow another experimenter to reproduce the experimental set up and obtain data from it comparable to the data recorded. Explanations and narrative along with the data and notes are important for orienting the reader. The notebooks will be graded at the end of each experiment: mid-way through the semester and at the end of the semester.
Data Reduction and Error Analysis for the Physical Sciences (Second Edition) by P. R. Bevington and D. K. Robinson is recommended for the course. (A useful reference with a more elementary treatment of error analysis is An Introduction to Error Analysis by J. R. Taylor.) The Bevington text includes the Turbo Pascal algorithms used in the Graduate Laboratory data analysis programs LINREG and ANALYSIS. A second recommended publication is the American Institute of Physics Style Manual. It is available on the web at http://www.aip.org/pubservs/style.html. This manual describes the preparation of manuscripts for publication. Use the American Institute of Physics style for figures, tables and references.
The PC's in the laboratory are available for data analysis and plotting. The Graduate Laboratory has a selection of analysis and plotting programs available for this purpose. The appendix of the Graduate Laboratory Manual describes the software.
Dell PC's are available in room 3333 (Grad Lab Library), and in the Physics Open Workstation Lab, room 3111 (OWL2).Storage of data or personal programs on the Laboratory's hard disks is risky; the disks are subject to periodic "cleansing'' without notice. Much of the software available in the Micro Labs is covered by copyright; it is illegal to copy these programs. It is the policy of th
2.1.3 Mössbauer Effect (2)
2.1.7 Critical Phenomena: Ferroelectric Crystals (2)
2.1.9 Acousto-optic Diffraction (2)
2.2.1 Second Sound in Liquid Helium II (2)
2.2.2 Superconductivity (2)
2.3.1 Compton Effect
2.3.3 Angular Correlations
2.3.4 Rutherford Scattering
2.4.1 Lifetime of the Cosmic Ray Muon
2.5.1 Doppler Free Laser Spectroscopy
2.7.1 Thermal Noise
2.7.2 1/f Noise Not Available Spring 2010
2.12.3 Critical Phenomena: Critical Opalescence (2)
3.1.1 Ion Channel Conduction
Safety depends on a common-sense approach to the hazards that exist in the laboratory. Students are responsible for working in a safe manner and in accord with the safety regulations established by the University's Department of Environmental Safety and the Graduate Laboratory Staff. These regulations are given in the University publications Radiation and Laboratory Safety Policies and Procedures and Radiation Safety Manual and the book Radiation Protection in the Radiologic and Health Sciences by Noz and Maguire. Of particular interest are the Material Safety Data Sheets (MSDS) for chemicals. These are available on the web http://www.inform.umd.edu/des/ls/index.html, or on the front of the chemical safety cabinet in room 3313. Information concerning suitable gloves for handling liquid chemicals can be found at http://www.inform.umd.edu/des/ls/safeskin.html.
Specific safety items:
• No smoking
• Eating and drinking only permitted in the Library, room 3333
• Radiation film badges to be worn at all times
• No open footwear
• Long hair must be confined.
• An emergency phone is located in the main corridor outside room 3303. This phone connects directly to Emergency Services.
Information about the experiments is available for student use. Material from the Library should not be removed from the Grad Lab suite except for copying. Additional reference material can be found in the Engineering and Physical Sciences Library. The Handbook contains complete bibliographic information for this purpose. Do not remove equipment manuals from the Laboratory. Original equipment manuals are available from the Laboratory Coordinator.
Equipment failures should be reported promptly so that repairs can be made expeditiously. Place malfunctioning equipment on the table in the hallway near room 3323 with a description of the failure and send an email to the coordinator.
Equipment and tools are not to be removed from the Laboratory.
C. Supplies and Parts
Parts and supplies may be obtained from Physics and Chemistry Stores. Account numbers are assigned as needed. Materials not available in the Stores may be ordered from outside vendors. Check with the Laboratory Coordinator.
D. Cryogenic Liquids
Liquid helium and nitrogen can be ordered only on certain days. Helium is ordered on Monday or Wednesday for delivery on Tuesday or Thursday. Liquid nitrogen dewars are filled on Monday, Wednesday, and Friday. Request for either of these cryogenic liquids must be made in advance. Orders for cryogenic materials will be placed only when the experiment is fully prepared for operation.
E. Laboratory Facilities
All of the facilities of the laboratory are available for student use.
Copies of some books and most journal articles referenced in this handbook are available in room 3333. The remaining reference material may be found in the Engineering and Physical Sciences Library. Equipment manuals are also available for use in the laboratory only and must not be removed from the laboratory area. Please return all reference materials to their respective files. These reference materials are part of the Graduate Laboratory's inventory.
Soldering irons as well as a selection of small hand tools are available for use in the laboratory. For more involved work the department has a student machine shop in Room PHY-0125. The supervisor of the shop will be pleased to answer questions and give advice. It is necessary to see him before starting any project in the student shop. For reasons of safety, unsupervised work in the shop is not permitted. Plastic and metal supplies are available in the student shop and in the main shop stockroom. Authorization from the Laboratory Coordinator is necessary.
Nuclear Instrumentation Modules (NIM) are stored in Room 3323, as are all radioactive materials. Radiation monitoring film badges are stored in the gray wall cabinet in Room 3333 and must be returned there when not in use. The personal radiation monitors must be worn at all times when in room 3323 or when using any radioactive materials. Radiation badge reports will be sent directly to the badge-holders.
Most of the instruments and expendable supplies are stored in room 3313. Students have self-service privileges in this room. It is required that all equipment and supplies will be returned to their proper places of storage when no longer needed.
Expendables and other small items not available in the laboratory may be obtained at the Physics Store (room 0104) and Chemistry Store (CHM-0202). Authorization from the Laboratory Coordinator is necessary.
F. Some Helpful Advice
Most instruments are more versatile than generally recognized. The operating sections of many instrument operation manuals have application notes. There is no need to use a more complicated instrument than is necessary.
G. Protection of Equipment
Equipment can be damaged if appropriate precautions are not observed. Read the operation manual before using any instrument for the first time. These manuals are found in the Graduate Laboratory Library in the files labeled "Manuals".
Most electronic instruments can be damaged by excessive voltage or current. Excessive voltage can be as low as 7 volts for some instruments.
There are several mechanical vacuum pumps in the laboratory. They should never be turned off and left with a vacuum at the pump intake port because oil may be drawn into the system. They may be left operating overnight pumping on a closed and leak free vacuum system.
Exposing photomultiplier tubes to light makes them noisy for an extended period. Photomultiplier tubes exposed to ambient light with accelerating voltage applied are instantly destroyed.
The heat of vaporization of helium is 6 cal/gm, by comparison, that of water is 596 cal/gm and that of nitrogen is 93 cal/gm. Helium transfers are only to be done by the Lab Coordinator, or staff.
to the Laboratory Guide
© Dept. of Physics, Univ. of MD
For queries regarding: