Thursday, May 28, 2015
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Today's New Announcements

Annual domestic hydrant flushing - June 6-7

WalkingWorks week two winners

Chicago Science Fest - May 28-30

International folk dancing Thursday evenings through June 11, cancelled today

LDRD preliminary proposals due May 29

Muscle Toning registration due June 2

Bill Kurtis presents "How the American Diet is Killing You" - June 3

Register now for LArSoft Workshop on June 3

Fermilab pool open June 9, memberships available

Managing Conflict (half-day) on June 10

Living Green! new Fermilab Library book display

Pilates registration

WalkingWorks program begins - register now

Wednesday Walkers

Pedometers available for WalkingWorks program

Swim lessons at Fermilab Pool

Adult water aerobics at Fermilab Pool

Outdoor soccer

Scottish country dancing meets Tuesday evenings at Kuhn Barn

English country dancing at Kuhn Barn

H4 Training discount for Fermilab employees


Fermilab Today

Director's Corner

Frontier Science Result

Physics in a Nutshell

Tip of the Week

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In Brief

LDRD proposals due Friday

Laboratory Directed Research and Development preliminary proposals are due tomorrow, May 29.

LDRD funds employee-initiated projects at the forefront of science and technology that are aligned with the missions of DOE and Fermilab. A first required step is a one-page preliminary proposal, due Friday.

Additional information is available on the LDRD website and from William Wester, LDRD coordinator.

Wellness Feature of the Month

June wellness and fitness classes

Complimentary Wellness

Bill Kurtis, broadcast journalist, presents "How the American Diet is Killing You"
Wednesday, June 3, noon-1 p.m.
One West
Seating is limited. Email or call x2548 to reserve your seat.

Lunch and Learn about Vein Disorders
Tuesday, June 16, noon-1 p.m.
Curia II
Presented by Presence Health.

Wednesday Walkers
Wednesdays. Depart from Wilson Hall east side at noon. Time, distance and speed are up to you.

Pool opens June 9
Tuesday-Friday, noon-7 p.m.
Saturday-Sunday, 1-6 p.m.
Closed Mondays

Pool memberships are sold in Wellness Office, WH15W.
Individual membership: $130
Family membership (up to four): $305
Extra family members over four: $55
Daily rate: $8/person. After 4 p.m.: $6/person
Day passes sold only at pool.
See more at Fermilab pool Web page.

Children's Swim Lessons and Adult Water Aerobics
Register online at Jeff Ellis Management. Registration is due June 8 for Water Aerobics and for Session One of Children's Swim Lessons. All other sessions due one week prior to start of class.

Fitness Classes

Mondays, June 1-July 13, noon-12:45 p.m.
Fitness Center Exercise Room
$87. Register now.

Muscle Toning by Bod Squad
Tuesdays and Thursdays, June 9-July 30, 5-6 p.m.
Fitness Center Exercise Room
$82. Register by June 2.

Athletic League

Outdoor Soccer
Tuesdays and Thursdays, 6 p.m.
Fermilab Village soccer field. Contact O'Sheg Oshinowo for more information

Employee Discounts
Visit the employee discount Web page.

Photos of the Day

Life of bison

A bison baby digs around in the muddy grass. Photo: Julianna Holden Mohler
Mothers nurse their young. Photo: Bridget Scerini, TD
Bison calves walk side by side with their parents. Photo: Ruben Carcagno, TD
Physics in a Nutshell

Magnets for measurements

Magnet systems in modern particle physics experiments are used to analyze particle charge and momentum, but the field is strong enough and covers enough volume to give a whale an MRI exam.

Broadly speaking, a modern particle physics detector has three main pieces: (1) tracking, which charts the course of charged particles by letting them pass through thin sensors, (2) calorimetry, which measures the energy of charged or neutral particles by making them splat into a wall and (3) a strong magnetic field. Unlike tracking and calorimetry, the magnet doesn't detect the particles directly — it affects them in revealing ways.

Magnetic fields curve the paths of charged particles, and the direction of curvature depends on whether the particle is positively or negatively charged. Thus, a tracking system with a magnetic field can distinguish between matter and antimatter. In addition, the deflection is larger for slow, low-momentum particles than it is for fast, high-momentum ones. Fast particles zip right through while slow ones loop around, possibly several times.

Both effects were used to discover positrons in 1932. A cloud chamber (tracking system) immersed in a strong magnetic field revealed particles that curved the wrong way to be negatively charged electrons, yet were also too fast to be positively charged protons. The experimenters concluded that they had discovered a new particle, similar to electrons, but positively charged. It turned out to be the first evidence of antimatter.

Today, most particle physics experiments feature a strong magnet. The radius of curvature of each particle's track precisely determines its momentum. In many experiments, these magnets are stronger than the ones used to conduct MRI scans in hospitals, yet are also large enough to fit a whale inside.

Most of these magnets work the same way as a hand-held electromagnet: a DC current circulates in a coiled wire to produce a magnetic field. However, particle physics magnets are often made of superconducting materials to achieve extremely high currents and field strengths. Some magnets, such as the one in CMS, are cylindrical for more precision at right angles to the beamline, while others, such as ATLAS's outer magnet, are toroidal (doughnut-shaped) for more precision close to the beamline. In some cases, an experiment without a built-in magnet can surreptitiously make use of natural magnetic fields: the Fermi-LAT satellite used the Earth's magnetic field to distinguish positrons from electrons.

Since the particle momentum that a magnetized tracking system measures is closely related to the particle energy that a calorimeter measures, the two can cross-check each other, be used in combination or reveal the particles that are invisible to tracking alone. Advances in understanding often come from different ways of measuring similar things.

Jim Pivarski

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In memoriam: Mary Barath

Former Fermilab Technical Division employee Mary Barath passed away on May 13.

A celebration of her life will take place on Saturday, May 30, at Ballydoyle Pub, 28 West New York Street, Aurora. A visitation will be held from 2-4 p.m., and a memorial service will be held at 4 p.m.

Read Barath's obituary.

In the News

Do atoms going through a double slit 'know' if they are being observed?

From Physics World, May 26, 2015

Does a massive quantum particle — such as an atom — in a double-slit experiment behave differently depending on when it is observed? John Wheeler's famous "delayed choice" Gedankenexperiment asked this question in 1978, and the answer has now been experimentally realized with massive particles for the first time. The result demonstrates that it does not make sense to decide whether a massive particle can be described by its wave or particle behaviour until a measurement has been made. The techniques used could have practical applications for future physics research, and perhaps for information theory.

Read more