Friday, Jan. 18, 2013

Have a safe day!

Friday, Jan. 18

3:30 p.m.

4 p.m.
Joint Experimental-Theoretical Physics Seminar - One West
Speaker: Tom Junk, Fermilab
Title: Final Combination of CDF's Searches for the Higgs Boson in the Standard Model and Extensions

8 p.m.
Fermilab Lecture Series - Auditorium
Speaker: Todd Kuiken, Northwestern University
Title: Building Bionics
Tickets: $7

Sunday, Jan. 20

2:30 p.m.
Gallery Chamber Series - 2nd Flr X-Over
Metropolis Quartet
Tickets: $17

Monday, Jan. 21

HOLIDAY - Martin Luther King Jr. Day

Tuesday, Jan. 22

3:30 p.m.


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a weekly calendar with links to additional information.

Ongoing and upcoming conferences at Fermilab


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Current Security Status

Secon Level 3

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Flags at full staff

Wilson Hall Cafe

Friday, Jan. 18

- Breakfast: Blueberry-stuffed French toast
- Cuban black bean soup
- Cajun turkey burger
- Enchilada-style beef and bean burrito
- Smart cuisine: Greek fish florentine
- Baked ham and Swiss ciabatta
- Assorted pizza
- Malaysian curried chicken

Wilson Hall Cafe Menu
Chez Leon

Friday, Jan. 18

Wednesday, Jan. 23
- Stuffed cabbages
- Mashed potatoes
- German chocolate cake

Chez Leon Menu
Call x3524 to make your reservation.


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Physics in a Nutshell

The atom splashers

In some Civil War battles, the shooting was dense enough and prolonged enough for bullets to collide. The atoms of the metal bullets redistributed themselves as a liquid, much like the quarks and gluons of heavy ion collisions. Image source:

In most particle physics experiments, physicists attempt to concentrate as much energy as possible into a point of space. This allows the formation of new, exotic particles like Higgs bosons that reveal the basic workings of the universe. Other collider experiments have a different goal: to spread the energy among enough particles to make a continuous medium, a droplet of fluid millions of times hotter than the center of the sun.

The latter studies, often referred to as heavy-ion physics, require collisions of large nuclei, such as gold or lead, to produce amorphous splashes instead of point-like collisions. Lead ions, for instance, contain 208 protons and neutrons. When two lead ions hit each other squarely head-on in the LHC, many of the 416 protons and neutrons are involved in the collision, unlike the single-proton-on-single-proton collisions used to search for the Higgs boson. With so many collisions in such close proximity, the debris of the nuclei mingles and re-collides with itself like atoms in a liquid. Instead of just splitting in half, the nuclei literally melt.

This is a bit like what happens when two bullets collide in mid-air. Immediately after impact, the atoms in the bullets have enough energy to temporarily melt. Similarly, the quarks and gluons in the colliding lead nuclei spread and mingle as a droplet of fluid before evaporating into thousands of semi-stable particles.

This short-lived state of quark matter is unlike any other known to science. All other liquids, gases, gels and plasmas are governed by forces that weaken with distance. Water, for instance, is made of molecules that electromagnetically attract each other and repel oil. Clouds of interstellar dust are gathered by gravity and congealed by electromagnetism. In contrast, the quarks and gluons loosed by a heavy-ion collision are attracted to one another by the nuclear strong force, which does not weaken with distance. As two quarks start to separate from each other, new pairs of quarks and antiquarks join the mix with an attraction of their own.

This difference in the strong force law leads to surprising effects in the droplet as a whole. Experiments indicate that it is dense and strongly interacting, but with zero or almost no viscosity. As a result, it splashes through itself without friction. This differs from colliding bullets, which behave like clay because of the viscosity of liquid metal.

Quark matter is the stuff the big bang was made of. In the first microseconds of the universe, all matter was a freely flowing quark-gluon soup, which later evaporated into the protons and neutrons that we know today. Yet it is far from understood. It can only be produced in collisions and it is so short-lived that its properties have to be inferred from patterns in the particles that spatter away. Heavy-ion collisions in the LHC and RHIC at Brookhaven will tell us more about the origin of our universe.

—Jim Pivarski

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In Brief

Cybersecurity and Java 7

Recently you may have heard that Java 7 users have been experiencing issues with computer security. The Fermilab Computer Security Team has taken protective measures but, for a variety of reasons, it has not yet declared this issue a "critical vulnerability," which requires the Fermilab community to take immediate action. See the reasons for this and read about protective measures and what you can do to avoid this and other vulnerabilities. (A KCA certificate is required to view.) Any further recommendations or configuration requirements will be announced to the laboratory community through the appropriate channels.

In the News

Scientists reassemble the backbone of life with a French particle accelerator

From Science Codex, Jan. 14, 2013

Scientists have been able to reconstruct, for the first time, the intricate three-dimensional structure of the backbone of early tetrapods, the earliest four-legged animals. High-energy X-rays and a new data extraction protocol allowed the researchers to reconstruct the backbones of the 360 million year old fossils in exceptional detail and shed new light on how the first vertebrates moved from water onto land.

Read more
In the News

Focus: Ground-based instruments could detect cosmic wall structures

From Physics, Jan. 11, 2013

One of the potential explanations for the Universe's mysterious dark matter and dark energy is a cosmic latticework of energetic "domain walls." In Physical Review Letters, a team proposes the first method to directly detect these structures as the Earth passes through them. They find that if such walls exist and are abundant enough, they may be detectable by a relatively cheap set of sensitive magnetic-field detectors at several locations on Earth.

Read more
Frontier Science Result: MINOS

Organizing the masses at MINOS

By combining its neutrino and antineutrino data sets, MINOS has provided first constraints on the spectrum of neutrino masses (represented by the sign of Δm2), the CP-violating phase δ, and whether muon or tau neutrinos are more strongly mixed with the so-called ν3 mass state (indicated by θ23). The relative goodness of each scenario is given along the vertical axis in terms of a difference of log-likelihoods. The parameter Δm2 and the angles θ13 and θ23 relate to the relative masses of the neutrinos and to how quantum mechanically "mixed" the three types are.

Over a decade ago the evidence became clear that neutrinos, which come in three varieties, can morph from one type to another as they travel, a phenomenon known as neutrino oscillation. By tallying how often this transformation happens under various conditions—different neutrino energies, different distances of travel—one can tease out a number of fundamental properties of neutrinos, for example, their relative masses. The MINOS collaboration has been doing exactly this by sending an intense beam of muon-type neutrinos from Fermilab to northern Minnesota, where a 5-kiloton detector lies in wait deep underground.

In this new result, MINOS has observed the rare case of muon-type neutrinos changing into electron-type neutrinos. This transformation is governed by a parameter known as θ13, and the MINOS data provide new constraints on θ13 using different experimental techniques than previous measurements. MINOS also collected data with an antineutrino beam, and the real excitement comes in when combining the antineutrino and neutrino data sets. Differences between the rates of this particular oscillation mode between neutrinos and antineutrinos would point to a violation of something called CP symmetry. While physicists know that CP symmetry is violated by quarks, it remains unknown whether the same is true for neutrinos. A new source of CP violation is required to explain why the universe began with more particles than antiparticles, and neutrinos could hold the key. (If the universe began with equal numbers of particles and antiparticles, they would have subsequently annihilated away, leaving nothing left over to make the stars and galaxies we have today.)

The neutrino-antineutrino oscillation comparison is not as straightforward as it could be, however. As MINOS' beam travels through the Earth's crust en route to Minnesota, the electrons present in the crust influence the traveling neutrinos and antineutrinos differently, inducing an asymmetry between them that has nothing to do with the fundamental one mentioned above. The size of this extra asymmetry depends on which neutrino is the heaviest. This is currently unknown, so comparing these oscillation rates actually provides information both on CP violation and on the spectrum of the neutrino masses.

While further data will be needed to bring the answers into sharper focus, MINOS is the first to use this accelerator-based neutrino-antineutrino technique to probe such deep questions in the neutrino sector, paving the way for the next round of measurements.

—Ryan Patterson, Caltech

Photo of the Day

Among the reeds

The world stands still on partially frozen Lake Law. Photo: Steve Krave, TD

Today's New Announcements

Fermilab Barn Dance - Jan. 20

Artist reception - Jan. 25

Scottish country dancing Tuesday evenings in Kuhn Barn

Fermilab Lecture Series - Building Bionics - Jan. 18

Gallery Chamber Series - Metropolis Quartet - Jan. 20

Series on the Bible book of Daniel - begins Jan. 22

NALWO Armenian cooking demonstration - Jan. 24

Fermilab Arts Series - Tomas Kubinek - Jan. 26

January 2013 float holiday for timecard use

UChicago panel discussion on Higgs discovery - Feb. 7

URA Visiting Scholars Program deadline - Feb. 25

2013 FRA scholarship applications accepted until April 1

Fermilab Management Practices courses available for registration

Interpersonal Communication Skills course offered in May

Abri Credit Union - member appreciation

International Folk Dancing Thursday evenings in Kuhn Barn

Indoor soccer

USA Athletic Club and Spa discount for employees

Interested in a Vaughan Athletic Center membership discount?

Employee discounts on AAA membership

Find new classified ads on Fermilab Today.