Friday, Oct. 18, 2013

Have a safe day!

Friday, Oct. 18

3:30 p.m.

4 p.m.
Joint Experimental-Theoretical Physics Seminar - One West
Speaker: Mark Williams, Indiana University; Kai Yi, University of Iowa
Title: Search for the X(4140) State in B+→J/ψφK+ Decays with the DZero and CMS Detectors

Monday, Oct. 21

2:30 p.m.
Particle Astrophysics Seminar - WH6W
Speaker: Ted Bunn, University of Richmond
Title: Interferometers for Cosmic Microwave Background Polarization Measurements

3:30 p.m.

4 p.m.
All Experimenters' Meeting - Curia II
Special Topic: T-992: Rad Hard Sensors for the SLHC

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a weekly calendar with links to additional information.

Ongoing and upcoming conferences at Fermilab


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Wilson Hall Cafe

Friday, Oct. 18

- Breakfast: French bistro breakfast
- Breakfast: chorizo and egg burrito
- Beer-battered fish sandwich
- Smart cuisine: teriyaki pork stir fry
- Vegetarian eggplant lasagna
- Cuban panino
- Breakfast-for-lunch omelet bar
- Tomato basil bisque
- Texas-style chili

Wilson Hall Cafe menu
Chez Leon

Friday, Oct. 18
- Lentil soup
- White fish with Moroccan spice marinade
- Couscous
- Moroccan vegetables
- Tangerine custard tart

Wednesday, Oct. 23
- Crispy salmon
- Spiced lentils
- Baked apples with calvados
- Custard sauce

Chez Leon menu
Call x3524 to make your reservation.


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Physics in a Nutshell

Seeing the world with neutrino eyes

A simulation of what the Earth would look like if we could see only neutrinos. The Earth is transparent because neutrinos pass through it easily, and the spots on the surface are nuclear reactors. (Data source: Atomic Energy Agency. View a version with continental outlines.)

On Feb. 23, 1987, neutrino detectors in Ohio, Japan and Russia observed a burst of neutrinos. This type of experiment usually only sees neutrinos produced in the sun and the far more energetic neutrinos produced in the Earth's atmosphere. These neutrinos trickle in at about 10 per day. In 13 seconds, however, the detectors saw 24 neutrinos. Hours later, astronomers witnessed the brightest supernova seen since the invention of telescopes. When the core of a star known as GSC 09162-00821 collapsed, 99 percent of its energy was radiated as neutrinos; the remaining 1 percent became a bright flash of light hours later.

Neutrinos are barely detectable particles produced in weak-force interactions, much as photons are particles of light produced in electromagnetic interactions. Unlike photons, neutrinos are so weakly interacting that they could pass through light-years of lead without much attenuation. If we could see the neutrinos, the universe would look quite different. We would be able to look directly at the core of the sun, where the nuclear reactions take place, rather than its relatively cool surface. The spinning Earth would look like the animation above, with a diffuse glow from natural radioactive elements in the Earth's crust and bright spots emanating from nuclear power plants, easily visible through the planet. If we could also selectively see neutrinos of different energies, we could focus on neutrinos from particle accelerators, which are typically much higher in energy than solar and supernova neutrinos and more consistent than the sparkle of neutrinos produced in the atmosphere by cosmic rays. I sometimes wonder if that would be the most conspicuous evidence of human civilization to faraway observers: high-energy neutrinos such as those from NuMI at Fermilab, revolving every 24 hours like a lighthouse beam.

However, just as there are extragalactic sources of ultra-high-energy cosmic rays, there may be ultra-high-energy neutrinos coming from active galactic nuclei, gamma-ray bursts and starburst galaxies, and they might also be formed when cosmic rays collide with photons. They may even come from decays of dark matter, if dark matter is not stable. Until last year, none of these ultra-high-energy neutrinos had been observed because so few neutrinos interact in a detectable way per cubic foot of ordinary matter. IceCube, an enormous detector that uses a billion tons of Antarctic ice as its detection medium, observed two ultra-high-energy neutrinos last year — each with about 100 times as much energy as an LHC collision. They may be the first extragalactic neutrinos seen since Supernova 1987A. If the signal is real and points back to a small region of the sky, we could be looking at a cosmic accelerator with neutrino eyes.

Jim Pivarski

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Photo of the Day

Reflections of fall

The air is getting crisper and colors are getting warmer. Wilson Hall stands tall on an early-morning fall day. Photo: Patrick Sheahan, AD
Special Announcement

Road D closed Oct. 21-Nov. 4

Road D in the vicinity of the IARC OTE Building construction will be closed beginning Monday. Click on the map to view the detour route.

Because of Road D improvements in front of the IARC Office Technical and Educational Building, part of Road D will be closed beginning Monday, Oct. 21. Access to all buildings in the area will remain open. See this map to view the detour route.

In the News

"Higgsogenesis" proposed to explain dark matter

From Nature, Oct. 4, 2013

A key riddle in cosmology may be answered by the 2012 discovery of the Higgs boson — now a leading contender for the 2013 Nobel Prize in physics on 8 October.

Two physicists suggest that the Higgs had a key role in the early Universe, producing the observed difference between the number of matter and antimatter particles and determining the density of the mysterious dark matter that makes up five-sixths of the matter in the Universe.

In a paper accepted for publication in Physical Review Letters, Sean Tulin of the University of Michigan in Ann Arbor and Géraldine Servant of the Catalan Institute for Research and Advanced Study in Barcelona, Spain, say that there may have been an asymmetry in the early Universe between the Higgs boson and its antimatter counterpart, the anti-Higgs.

"We really make the Higgs a key player, whereas in many other cosmological theories it's just a by-product," says Tulin.

Read more

Frontier Science Result: MINERvA

Seeing more from the nucleus than the sum of its parts

Ratio of iron (top) and lead (bottom) to plastic neutrino cross sections (interaction probability) as a function of how much momentum the struck quark has compared to a proton or neutron in the nucleus.

Para una versión en español, haga clic aquí.

We can all tell that a lump of coal, a steel ball bearing and a lead brick are very different from one another, just by using our eyes. On the other hand, we know they are all just made up of different numbers of protons and neutrons in the nucleus, the atom's inner core. At MINERvA we use neutrinos to see these materials, and sure enough, the protons and neutrons seem to know whether they are inside coal, steel or lead. The surprise is that these "nuclear effects" are different from what you would predict from measurements using electrons to see those same nuclei.

The nucleus is a complex bound state of proton and neutrons, which are themselves complex bound states of quarks and gluons. The theory of particle physics tells us precisely how a neutrino interacts with a single quark inside a proton or neutron. However, in MINERvA, each neutrino hits not only individual quarks, but also sometimes protons or neutrons, or sometimes even the whole nucleus. Neutrino interactions also happen in many different ways: Sometimes they only change a neutron into a proton, and sometimes they break up a whole nucleus.

When MINERvA looked at the first kind of interaction, we saw that the previously understood simple picture of what the protons and neutrons are doing inside carbon was not correct. For this result, we look at a much larger range of neutrino interactions and a larger range of nuclei. Once again we have found that our simple model is not correct.

The above figure shows the measured probabilities (or cross sections) of a neutrino interacting with the material in different MINERvA targets. Specifically, they show the ratios of the neutrino cross sections for iron and for lead to those for plastic in different Bjorken x ranges. "Bjorken x" is the scientific term for how much of the proton's or neutron's momentum is carried by the struck quark.

The measurement is compared with the model used by most neutrino experiments, and we see that the heavier the nucleus, the more the data do not agree with the model: The data tell us that the heavier the nucleus, the more the quarks can get extra momentum. This would be possible if a quark can get extra momentum from the rest of the nucleus, a phenomenon that is not yet in the model. To obtain the best measurements of neutrino oscillations in the future, we will need to improve these models so that they can reproduce what we measured here.

Brian Tice of Rutgers University is writing his thesis on this MINERvA finding. He described the result at the Oct. 11 wine and cheese seminar. View the talk.

Mousumi Datta

Brian Tice of Rutgers University discusses this MINERvA result at the Oct. 11 wine and cheese seminar.

Wilson Fellowship application link in Thursday's issue

In Thursday's article on applying to Fermilab's Wilson Fellowship, a link to the fellowship application page pointed to the wrong page. To apply for the Wilson Fellowship, visit this Web page. Thursday's article has been updated. Fermilab Today regrets the error.


Today's New Announcements

Deadline for Wilson Fellowship application - Nov. 1

Employee Health & Wellness Fair - Oct. 21

Zumba Fitness - starts Oct. 22

Zumba Toning - starts Oct. 24

Fermilab Family Halloween Party - Oct. 25

Office of Science's Patricia Dehmer speaks at UChicago - Nov. 5

Heartland Fermilab walk-in blood drive - Nov. 5 and 6

Lepton flavor violation course in lecture series

Donate winter wear for Fermilab Coat Exchange

New wireless guest network service now available

CRC Handbook of Chemistry and Physics is online

SPIE digital library online trial at Fermilab

Money just got cheaper

Accelerate to a Healthy Lifestyle

Indoor soccer on Tuesdays and Thursdays

Basketball open gym on Wednesdays

Ringling Bros. and Barnum & Bailey discounts

Find new classified ads on Fermilab Today.