 | Thursday, November 9, 2006 |
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Thursday, November 9 THERE WILL BE NO ALCPG ILC PHYSICS AND DETECTOR SEMINAR THIS WEEK
Friday, November 10 Click here for NALCAL, a weekly calendar with links to additional information. |
 Mostly Sunny 61º/41º
Extended Forecast |
Secon Level 3 |
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Thursday, November 9 -Santa Fe Black Bean -Sloppy Joe -Stuffed Peppers -Sauteed Liver and Onions -Baked Ham and Swiss on a Ciabatta Roll -Assorted Slice Pizza -Crispy Fried Chicken Ranch Salad |
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Thursday, November 9 Dinner Caribbean Root Vegetable Soup Red Snapper Vesuvio Steamed Rice Green Beans & Red Onions Banana Walnut Spring Rolls w/Caramel Rum Sauce
Wednesday, November 15
Chez Leon Menu |
| Fermilab Today is online at: http://www.fnal.gov/today/ Send comments and suggestions to today@fnal.gov Fermilab Today archive Fermilab Today PDF Version Fermilab Result of the Week archive Fermilab Safety Tip of the Week archive Fermilab Today classifieds Subscribe/Unsubscribe to |
| Fourth-grade scouts learn some college-level physics | |
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It's Friday at the Lederman Science Center, and docent Mary Hawthorne is placing a glass jar upside-down over a lit candle in a tin full of water. "What will happen?" she asks. The room is full of boy scouts, pumping their hands in the air to answer her question. The fourth-grade St. Charles boy scout den is spending the afternoon with Hawthorne to earn science pins for their uniforms. Hawthorne is teaching them about the Bernoulli Effect, Newton's laws of motion, Pascal's law, and how hydraulics and electric fields work. In one of her many demonstrations, she shows how cold temperatures can enhance the field of a superconducting magnet--she allows a magnet to levitate over a piece of superconducting wire cooled in liquid nitrogen. The scouts are really thinking about this. Their eyes are glued to Hawthorne, and they gasp when water spontaneously fills upside-down glass jars, small magnets hover inside copper tubes, and rubber balls crack into pieces after being dunked in liquid nitrogen. Scouts try to explain each outcome, sometimes using Newton's laws to justify their answer. "I like your balance between excitement and behavior," Hawthorne tells the group. "It's really working for me."
Classes like this have been going on at Fermilab for over two years. They are open to any den interested in earning a science pin. "We offer engineering pins, too," said Sue Sheehan, who also leads scout activity sessions at the Lederman Center. "In the engineering lesson, students get to make catapults." You can learn more about the scout program and other course offerings on the education website. |
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USA Today, WonderQuest November 8, 2006: Photon on a drunk walk Q: How many years does it take for heat generated in the sun's core to reach its outer layer, the photosphere? (KS, Kuala Lumpur, Malaysia) A: Asking how long photons take to migrate to the sun's surface can start a fight. Some solar physicists say 17,000 years, others 40,000, some 170,000, still others 1,000,000 years. It's a fairly tricky question, since the sun's core - where a photon starts - is a bad place to make much progress. Let's follow a photon from its birth in the thermonuclear furnace at the sun's center, across 525,000 kilometers (more than the distance from Earth to the Moon) to the convective shell, and then follow the heat transfer to the sun's surface. The sun's core is a hellish place. Gravity squeezes inward, compressing matter to densities unlike any matter found on Earth - about eight times the density of gold. Furthermore, the center sizzles at a temperature (27 million degrees Fahrenheit) hot enough to get two positively-charged hydrogen nuclei (protons) moving fast enough to collide together with enough energy to overcome their mutually repulsive electrical force. At 27 million degrees those guys smack together hard enough to fuse into a heavy hydrogen atom, and release an anti-matter electron (positron) and a neutrino (a massless, chargeless particle, moving at light speed).
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| The puzzle of a lifetime | ||
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Particle physicists make a living piecing together intricate puzzles of data and theoretical predictions. Usually, each new piece of the puzzle clarifies the picture being assembled. In the case of the Λb hadron, however, the picture seems to be getting fuzzier as measurements pour in. First observed more than a decade ago, the Λb vexes physicists because its measured properties disagree with careful predictions.
Hadrons are bound states of two or more quarks, and the Λb is the lightest three-quark hadron containing a b quark. It is believed that the heavy b-quark dominates the decay of any particle containing a b quark; therefore, any particle whose heaviest constituent quark is a b-quark should have the same lifetime. Actual measurements show lifetime differences between various b hadrons, indicating that the other, lighter, quarks also play a significant role in the decay process. Sophisticated calculations predict that the Λb baryon should have a shorter lifetime than almost all of the other b hadrons. The DZero experiment has recently reconstructed about 174 complete Λb decays and has used this sample to measure its lifetime. The result of (1.30 ± 0.15) × 10-12 seconds (less than the time it takes light to travel the width of a hair), is one of the most precise measurements of the Λb lifetime to date. It confirms earlier shorter lifetime results from other experiments, but is considerably shorter than a recent similar measurement reported by the CDF collaboration. Therefore the level of agreement between the data and theory remains open. It is widely expected that new analysis techniques and additional Tevatron data will shed more light on the problem. For now, the Λb remains the puzzle of a lifetime.
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Above: Eduard de la Cruz Burelo (Univ. Michigan) and Natalia Panikashvili (Technion, Michigan visitor) contributed to this analysis. Below: The muon algorithm group at DZero provides a crucial
contribution to all analyses that rely upon good-quality muon
identification. From left, top row: Raimund Stroehmer, Philippe
Calfayan, Thomas Gadfort, Michel Eads, Boris Tuchming. Bottom row:
Marion Arthaud, Frederic Deliot, Mark Owen, Linda Stutte, Andrzej Zieminski.
 Result of the Week Archive
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November 6 - 8 - One store provided 20 hours and 26 minutes of luminosity - 400 MeV Debuncher cavity temperature problems - Recyclers looses 100.0E10 antiprotons
Read the Current Accelerator Update |
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Entertainment Book Sale in the Atrium Would you like to save money on restaurants, stores and entertainment? Entertainment discount books will be sold in the Atrium Wednesday, November 15, and Thursday, November 16, from 11:30 a.m. until 1:00 p.m. Cash, checks, Visa and MasterCard will be accepted. You can also buy the books anytime during business hours in the Recreation Office. |
