Is CARBON Hard or Soft?
	Diamonds are made of carbon. They are among the hardest of materials and are used to cut glass and steel. Graphite is also a form of the element carbon. It rubs off easily on paper, which is why we use it to make pencil leads.If diamonds and graphite are made out of the same element, why do they look so different and behave so differently? Take a closer look: Above is a drawing of the crystalline structure of a diamond. The spheres represent carbon atoms; the lines connecting the atoms represent chemical bonds. Each carbon atom is at the center of a four-sided pyramid, or tetrahedron, formed by the neighboring carbon atoms to which it is bonded. Above is a drawing of a graphite crystal. A few carbon atoms are bonded vertically to those above and below, but most are only attached to neighbors in the same horizontal plane. Do these drawings suggest a reason why diamonds are hard while graphite breaks apart easily? The answer has to do with how the carbon is arranged in the two materials–with the materials’ structures. to try an activity that explores this idea further: Materials scientists are interested in knowing how a material’s macroscopic properties– such as hardness, resistance to extreme temperatures, electrical conductivity, and many others–are related to its atomic structure. This knowledge can be used to improve materials and develop new materials to meet specific needs.For instance, materials scientists at Lawrence Berkeley National Laboratory recently invented a new material that is harder than diamonds. It may be used as an inexpensive substitute for diamonds or to carve diamonds into intricate shapes for use in electronic devices. Scientists are also experimenting with a recently discovered carbon structure, called buckminsterfullerene (or fullerene for short, or “buckyballs” for shorter) that looks like this: The buckyball is named after Buckminster Fuller, the inventor of the geodesic dome. One of the many interesting qualities of buckyballs is that atoms of other elements can be put inside the buckyball “cage,” creating all sorts of possibilities for new materials.Studying a material’s structure often means looking at its atomic structure–how its atoms fit together and interact. The ALS allows scientists to study materials on the scale of their atomic structure. To find out how researchers are using the ALS to study materials, just click on one of the following: Kevlar–The Wonder Material Selenium: A Window On Wetlands

What’s going on inside this building?

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The ALS is a research facility used by scientists to: Explore the properties of materials Analyze samples for trace elements Probe the structure of atoms and molecules Study biological specimens Investigate chemical reactions Manufacture microscopic machines.

The ALS produces light–principally x rays–with special qualities. Scientists use these x rays as a tool to do their work, just as dentists use x rays as a tool.Many scientists working on different projects can use the ALS at the same time. For example, one scientist might be checking samples of mud for tiny amounts of a toxic contaminant, while another might be investigating a polymer to find out how its molecules are arranged. Fact: X rays have shorter wavelengths than visible light. But both are light, also calledelectromagnetic radiation.

Why is the ALS so large?

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To produce light of the wavelengths and brightness that scientists want, the ALS designers had to create a large machine. Its largest component, the storage ring, has a diameter two-thirds the length of a football field.The storage ring is a tubular vacuum chamber made to:

• Hold an electron beam travelling through it at nearly the speed of light.
• Maintain the high energy of the electron beam.

As the electrons circle the ring, they give off light. The ring must be as big as it is to maintain the electron beam at 1.5-1.9 billion electron volts, the energy required to produce light of the desired wavelengths and brightness.For more information, see ALS Components.

Fact: Light produced by machines that operate like the ALS is called “synchrotron radiation.”ALS floor diagram. Why is light from the ALS a useful tool?

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produces light in the far ultraviolet and soft x-ray regions of the electromagnetic spectrum. This light has wavelengths from 0.0001 micrometer to 0.1 micrometer.

object is closest in length to a micrometer 

• a submarine
• an ant
• the diameter of a human hair
• a virus

Here are some reasons why light from the ALS is a good tool for exploring materials.

Reason 1

Light from the ALS can penetrate materials. Just as your dentist uses x rays to see inside your gums, scientists use the light from the ALS to look inside materials.

Dental x ray.

Why do dental x rays penetrate your gums and not your teeth

Reason 2

It is impossible to “see” anything smaller than the wavelength of the light you are using. So to study atoms or molecules, you must use light waves about their size or smaller. The ALS produces light with wavelengths about the sizes of atoms, molecules, chemical bonds, and the distances between atomic planes in crystals.

Atoms, chemical bonds, and the distances between atomic planes in crystals all measure a few angstroms, about the same as the wavelengths of light from the ALS.

Reason 3

Photons (or particles of light) from the ALS have the right energies to interact with many electrons in atoms.

The diagram below shows what can happen when light shines on a material.

Electrons may absorb the photons’ energy and escape from the material (as shown at the top of the diagram). Scientists in the late 19th century observed this phenomenon and called it the photoelectric effect.

OR

Electrons in the atoms of the material may absorb the photons’ energy and jump to a higher energy level. When an electron does this, its atom is said to be “excited.” Soon the electron loses the extra energy and returns to a lower level–a process called de-excitation. Often this lost energy escapes from the atom in the form of photons. Excitation and de-excitation are shown at the bottom of the diagram.

Also, you may observe no interaction. Can you guess why?

Scientists at the ALS detect and analyze the escaping electrons or photons to learn more about the structure and behavior of atoms and the materials in which they are found. Analyses like these serve many purposes, for example:

• Detecting the presence and quantity of trace elements from their unique emission patterns (see Selenium: A Window On Wetlands).
• Providing images that show the structure of materials (see Kevlar–the Wonder Material).

Reason 4

The ALSis one of America’s brightest soft x-ray sources available for researchers. The x rays produced here are a hundred million times brighter than those from the most powerful x-ray tube, the source used in a dentist’s machine. High brightness means that the x rays are highly concentrated. Many x-ray photons per second can be directed onto a tiny area of a material.

(left) Brighter; (right) not so bright.

Reason 5

Besides their brightness, x rays from the ALS have other useful characteristics such as tunability, near-coherence, pulsed nature, and polarization.

Since the ALS produces x rays, why couldn’t scientists just use an x-ray tube as a dentist does, instead of the ALS?

Here are some facts:

ALS X Rays	X Rays Produced by an X-Ray Tube
Penetrate matter	Penetrate matter
Have wavelengths near the size of atoms and molecules	Have wavelengths smaller than the sizes of many atoms and molecules
Have the right energies to interact with electrons in light atoms such as carbon and oxygen	Have energies too high to interact with many electrons in light atoms but can interact with those in heavy atoms such as gold
ALS “soft” x-rays are brighter than any other x-ray source in America; similar to the light from a laser	Are not bright enough for high-resolution experiments; more like a floodlight than a laser
Are produced in tiny pulses constantly for 6 hours or more	Can be produced in a single short burst (i.e., dental x-ray tube)

X-ray tubes are found in the laboratory as well as in dental offices and continue to be used for many experiments. But the ALS has advantages over x-ray tubes when it comes to investigating most materials.

An obvious advantage is the length of time the x-ray beam lasts. A beam from the ALS continues for hours, while the beam from an x-ray tube is often limited. A scientist could not use the light generated by an x-ray tube for experiments that take much time, for example, scanning the surface of a material for impurities.

Also, x rays from the ALS have the right energies to interact with many electrons in lighter atoms, which make up most common materials. Interaction must take place; otherwise, an experiment will not yield information. X-ray tubes produce photons with higher energy than those from the ALS–an advantage for imaging objects made of very heavy elements such as gold (Au). But these energetic photons would pass right through materials made up of light atoms and not interact at all.

The greatest advantage of the ALS is its brightness. You could compare an x-ray beam from the ALS with a laser and one from an x-ray tube with a floodlight. While they both might deliver an equal number of photons per second, those from the ALS are concentrated on a small area, whereas those from the x-ray tube are widely scattered. A higher concentration of photons on a smaller area allows scientists to increase the specificity of their experiments. They can study smaller objects or choose more specific photon energies (down to tenths of electron volts) to study a very specific target. Activity

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If you could use the ALS or an x-ray tube as your source of photons, which would you choose to solve the following problems?1. I have a material suspected to be contaminated with small amounts of copper (Cu). If it is contaminated, I need to know how the copper is distributed in the material. Which x-ray source should I use, and why 

2. I need photons with an energy of exactly 285.5 eV (electron volts). Photons with this energy are absorbed by an aromatic group in a fiber I am studying, and I want to make an image of the fiber’s cross section. Which x-ray source should I use, and why 

3. Archaeologists have found a sealed urn and suspect that it contains gold (Au) coins. Which x-ray source would I use to determine the presence of the coins, and why 

4. I’m a curator for a large art museum, and I need to know if this urn is genuine before we purchase it from the art dealer. All of the art historians say that the style of the urn and the designs painted on it are from the same time period and location as that which the dealer claims. However, I have reason to believe that the urn might be a reproduction from another time period. The art conservation literature states that a distinguishing characteristic from this time period is the presence of manganese (Mn) in a layer of pigment. Which x-ray source should I use to determine whether there is manganese in the pigment, and why 

5. I need an x-ray source to determine how quickly a chemical compound found in automobile exhaust is converted to a component of smog. It is suspected that this compound is converted at very fast rates–in picoseconds. (Picoseconds are trillionths of a second.) Which source of x rays should I use to detect the change 

6. I fell down, and I heard a crack. My arm hurts a LOT. Which x-ray source should be used to tell if my arm is broken, and why  ALS Components

U.S. Department of Energy’s Decades of Discovery
The following list of discoveries is grouped by general discipline—the numerical order is random and not ranked by importance.

Biological and Environmental Research

73. Improving the Realism of Global Simulations

74. Decoding the Human Genome

75. Verifying the “Third Branch of Life”

76. The World’s Toughest Microbe

77. The Smallest Genome that Sustains Independent Life

78. Speeding Up the Process of Gene Discovery

79. Engineered Enzyme Accelerates DNA Sequencing

80. Tiny Capillaries Have Giant Impact on DNA Sequencing

81. “Painting” Chromosomes for Quick and Easy Analysis

82. Putting a Virus to Practical Use

83. Unraveling the Role of DNA Repair

84. Of Mice and Men

85. The Role of the Extracellular Matrix in Cancer

86. New Tools for Structural Biology Research

87. The Structure of Nature’s “Molecular Machines”

88. Studies of Protein Structure Help Fight Lyme Disease

89. Accelerating the Study of Proteins

90. Optical Probes for Imaging Single Molecules

91. MicroPET Enhances Studies of Small Animals

92. Mapping Human Brain Function

93. Improving Neutron Beams for Cancer Treatment

94. The Biochemistry of Human Addiction

95. Observing Chemical Changes in Living Cells

96. Modeling and Simulating Environmental Problems

97. Discovering the Processes of Acid Rain

98. Predicting Effects of Elevated Carbon Dioxide

99. Clues to the Location of the Missing Carbon Dioxide

100. Human Effects on Global Warming

101. Listening to the Ocean’s Temperature

U.S. Department of Energy’s Decades of Discovery

The following list of discoveries is grouped by general discipline—the numerical order is random and not ranked by importance. Plasma Physics 57. Stable Confinement of High-Pressure Plasmas 58. The Role of Currents in Plasma Confinement 59. Reducing Plasma Turbulence 60. Measuring the Magnetic Field Inside Plasmas 61. A New Magnetic Container for Super Hot Plasmas 62. Modeling Large Systems of Particles 63. First Achievement of Fusion Temperatures in the Laboratory 64. A New Plasma Confinement Regime

U.S. Department of Energy’s Decades of Discovery

The following list of discoveries is grouped by general discipline—the numerical order is random and not ranked by importance. High Energy and Nuclear Physics 29. First Evidence of a Third Family of Fundamental Particles 30. Discovery of One of the Smallest Particles of Matter 31. A Limit on the Complexity of the Universe 32. Completion of the Third Generation of Matter 33. Confirmation of the Unification of Two Fundamental Forces 34. Methods for Complex Calculations 35. Zeroing in on the Elusive Higgs Boson 36. The Missing Solar Neutrinos 37. Evidence for Neutrino Mass 38. Setting Limits on the Mass of the Electron Anti-Neutrino 39. Beyond the Standard Model? 40. Unraveling the Mystery of Antimatter 41. Detecting the Afterglow of the Big Bang 42. The Inflationary Universe 43. Expansion of the Universe is Accelerating 44. The Most Distant Object Ever Observed 45. “The Stars Above Us, Govern Our Conditions” 46. Rare Double Beta Decay Process is Observed 47. Unusual Nuclei May Answer Long-Standing Questions 48. A Theory for Deducing Quark Behavior 49. The World’s Most Powerful Accelerator 50. First Linear Collider Offers New Possibilities 51. World’s Most Intense Source of Polarized Electrons 52. Lifetime of the Bottom Quark 53. New Clues to the Disappearance of Antimatter 54. The Highest-Energy Atom Smasher 55. Why Dinosaurs Are Extinct 56. Understanding and Applying Superstring Theory

U.S. Department of Energy’s Decades of Discovery

The following list of discoveries is grouped by general discipline—the numerical order is random and not ranked by importance. Basic Energy Sciences 1. Adenosine Triphosphate: The Energy Currency of Life 2. Making Better Catalysts 3. Understanding Chemical Reactions 4. New Types of Superconductors 5. Development of Neutron Scattering Facilities 6. Development of Synchrotron Radiation Light Sources 7. Development of Lithium Batteries 8. A New Class of Carbon Structures 9. Engineering Organisms to Make Valuable Biomaterials 10. Heavy Element Chemistry 11. Improving Intermetallic Compounds 12. Ion Beam Techniques Enhance Materials Science 13. Preventing Radioactive Contamination 14. Explaining and Applying Magnetism 15. Modeling Metals 16. Organic-Based Magnets: A New Frontier 17. Manipulating Light in Photonic Crystals 18. Extending the Power of Nuclear Magnetic Resonance Techniques 19. Saving the Earth’s Ozone Layer 20. Making Solar Energy More Affordable 21. Enhancing Separations and Analysis 22. Sequencing the First Plant Genome 23. New Opto-electronic Materials and Devices 24. Unraveling the Mystery of High-Temperature Superconductivity 25. Harnessing the “Thermoacoustic” Effect 26. Metallic Glasses with Extraordinary Properties 27. Extending the Science of Transition Metal Nitrides 28. A New Type of Microscopy

• I.   Astronomy of the Earth’s motion in space.
• II.   Newtonian mechanics.
• III.   The Sun
• VI.   Spaceflight and spacecraft
  also …. an introduction for teachers,   and:
• A Math Refresher.
• Helpful Material including
• Glossary
• Questions and Answers
• A Timeline and more.
• Also           Items of interest to educators
  (a guide, problems, concepts, article in “The Physics Teacher.”)
• A set of Lesson Plans
• (NASA site)   Objects and phenomena currently visible on the night sky
  Translations into
• Spanish by J. M. Mendez, H. Chávez, et al.
• French by Dr. Guy Batteur.
• Italian by Giuliano Pinto
• A message for home-schooling parents here

Then + Now A brief overview of this Web site that compares what we knew in 1900 to what we know today That’s My Theory Meet some of the scientists who made twentieth century history on this made-for-the-Web game show On the Edge These comic-book style stories take you back through time and present scientists soon after they made their discoveries You Try It Cool activities, including Atom Builder, Probe the Brain, and Technology at Home (requires Shockwave plug-in) People and Discoveries A databank of biographies of scientists and descriptions of key events and discoveries About the Television Series Program descriptions, TV broadcast schedule, excerpts from the companion book Resources for Educators Educator’s guide, and information about a science camp-in, a science demonstration, how to order a poster, and more What’s Happening in Your Area Find out what Science Odyssey activities and events are happening near you

Major funding is provided by the National Science Foundation.	Corporate sponsorship is provided by IBM. IBM is a registered trademark of IBM Corporation.	public television viewers, the Corporation for Public Broadcasting,The Arthur Vining Davis Foundations,Carnegie Corporation of New York, andBecton Dickinson and Company.	125 Western Ave Boston, MA 02134 A production of WGBH Boston 617. 492.2777

Math Refresher: This brief overview covers useful high-school math you may have forgotten. Includes basic formulas for sinusoid and logarithmic functions, a discussion of log scales, and discrete probability. Includes a list of recommended inexpensive reference books. Any suggestions for additions to the list welcomed. By William Stallings. Updated 25 July 2005.
Number Systems: Decimal, binary, hexadecimal, with a discussion of conversion from one system to another. By William Stallings.
Queuing Analysis: A practical guide to an essential tool for computer scientists. By William Stallings.
Theoretical Computer Science Cheat Sheet: By Professor Steven Seiden. Ten pages of commonly used formulas and other useful information for computer scientists.
Ask Dr. Math An excellent source of information on many math area. The emphasis is on high school math but college-level math is also covered.
The Mathematical Atlas: A very large collection of articles about aspects of mathematics. Each article gives a basic introduction to the subject, applications and related fields, and selected topics. There are also many references to resources, both books and online, that discuss the topic in greater detail.
Applied Mathematics: Links to Math resources on the Web, organized by topic, plus by keyword search. The site also shows the level of mathematical background to read the materials.
MathWorld: By the makers of Mathematica. Extensive, useful collection of information.
Math Tables and Formulas: Tables featured include Trigonometric Identities, Derivatives, Indefinite Integrals, Common Integrals, and Binomial Coefficients and Formulas, among others. A search engine and links to other S.O.S. sites and the S.O.S. Mathematics Cyberboard (for posting questions) can also be found here.
Math Reference Tables: Excellent collection of downloadable math tables.
Prime Mathematics Encyclopedia: Large collection of entries on mathematical terms and concepts.
Elementary Computer Mathematics A basic survey. Includes Java-generated problems with solutions.
Sage This computer algebra/computer mathematics package has the power and flexibility of Mathematica, Maple, or MATLAB. It is open source, free, and platform-independent. If you master one math package, this is the one to pick.

NSF and the Birth of the Internet — Text-only | Flash Special Report
Resources

ILLUSTRATIONS

Maps of Internet Growth 1960s through 1990s (pdf file)
Map of the Internet 2007 (pdf file)

DOCUMENTS

Report of the Panel on Large Scale Computing in Science and Engineering

http://www.pnl.gov/scales/docs/lax_report_1982.pdf

Also known as the Lax Report, this report in 1982 was influential in the creation of NSF’s supercomputing centers and efforts to network them together, leading to the NSFNET.

Sharing the Supercomputers
http://query.nytimes.com/gst/fullpage.html?
res=940DEEDB143AF93AA15751C1A96E948260
John Markoff of the New York Times wrote about the NSFNET project in this 1990 article.

Management of NSFNET
http://www.eric.ed.gov/ERICWebPortal/custom/portlets/
recordDetails/detailmini.jsp?_nfpb=true&_&ERICExt
Search_SearchValue_0=ED350986&ERICExtSearch_SearchType_0=no&accno=ED350986
A transcript of a 1992 hearing before the U.S. House of Representatives Subcommittee on Science of the Committee on Science, Space, and Technology, which had oversight over the NSFNET project

NSFNET: A Partnership for High-Speed Networking Final Report
http://www.merit.edu/about/history/pdf/NSFNET_final.pdf
This report was produced in 1995 by MERIT Networks, Inc., one of the original NSFNET partners. It provides a summary of the project and the conditions that lead to the decision to decommission the network in 1995.

Retiring the NSFNET Backbone Service: Chronicling the End of an Erahttp://www.merit.edu/networkresearch/projecthistory/nsfnet/nsfnet_article.php
A year after the NSFNET was retired in 1995, Susan R. Harris, Ph.D., and Elise Gerich wrote this article about the project for the journal ConneXions.

OTHER RESOURCES

TCP/IP
http://en.wikipedia.org/wiki/TCP/IP_model
An explanation of TCP/IP from Wikipedia

NSFNET Diagrams
http://www.merit.edu/networkresearch/projecthistory/nsfnet/nsfnet_maps.php
Diagrams of NSFNET throughout its development from MERIT Networks, Inc.

NSFNET on Wikipedia
http://en.wikipedia.org/wiki/NSFNet
NSFNET entry on Wikipedia.org

NSFNET Conference
http://www.nsfnet-legacy.org/event.php
In November, 2007, over 200 of the researchers and scientists who worked on the NSFNET project gathered in Arlington, Virginia to reflect on their experiences. Video from the three-day event are available online.

Internet2
http://www.internet2.edu/
Internet2 is a consortium of research and educational organizations that are working to facilitate the development, deployment and use of revolutionary Internet technologies.