Thursday, Aug. 30, 2012

Have a safe day!

Thursday, Aug. 30

1 p.m.
Computing Techniques Seminar - Racetrack (WH7X)
Speaker: Qiming Lu, Fermilab
Title: Multi-core Optimizations for Synergia2

2:30 p.m.
Theoretical Physics Seminar - Curia II
Speaker: Marco Zaro, Université Catholique de Louvain
Title: NLO Phenomenology with Madgraph

3:30 p.m.


Friday, Aug. 31

3:30 p.m.

4 p.m.
Joint Experimental-Theoretical Physics Seminar - One West
Speaker: Warren Huelsnitz, Los Alamos National Laboratory
Title: New Results from MiniBooNE's Search for Short Baseline Neutrino Oscillations

Click here for NALCAL,
a weekly calendar with links to additional information.

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Wilson Hall Cafe

Thursday, Aug. 30

- Breakfast: sausage gravy omelet
- Green pork chili
- Surfside tuna melt
- Mom's meat loaf
- Smart cuisine: finger-lickin' oven-fried chicken
- Crispy buffalo chicken wrap
- Bacon cheeseburger pizza
- Greek chicken salad

Wilson Hall Cafe Menu

Chez Leon

Friday, Aug. 31

Wednesday, Sept. 5
Menu unavailable

Chez Leon Menu
Call x3524 to make your reservation.


Fermilab Today

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Result of the Week

CMS Result

Physics in a Nutshell

Tip of the Week

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World-record quality factor achieved at Fermilab

Scientist Anna Grassellino of TD's SRF Development Department worked to develop techniques for maximizing the quality factor in bulk-niobium accelerator cavities. Photo: Reidar Hahn

Sometimes it pays to dust off old papers for new ideas.

Earlier this year, TD scientist Anna Grassellino began researching past successes and failures of accelerator cavities made of bulk-diffused niobium-nitride. Scientists reported less than stellar results in their tests in the 1990s and, in the years since, appeared to have mostly abandoned the material as a possibility for superconducting cavities. But Grassellino believed trying niobium nitride would be worth another go-round.

Her effort paid off. This month, Grassellino reported a world-record measurement on a 1.3-gigahertz, single-cell niobium cavity heat-treated in a nitrogen-rich atmosphere. The cavity achieved a quality factor of 7.5 x 1010 at 2 Kelvin and at a 20 megavolt-per-meter peak surface electric field. The measurement is almost twice that of the next-highest reported quality factor of any accelerator cavity. It bodes well for superconducting radio-frequency research.

"We're very excited," she said. "This is a milestone that sets completely new boundaries for SRF technology."

A cavity's quality factor, Q for short, is a measure of how efficiently energy is stored in the cavity. The energy stored in the cavity helps accelerate particle beams, which travel down the cavity's axis.

For the last several years, researchers have been developing cavities made of pure niobium for the next generation of particle accelerators. Scientist Alexander Romanenko, TD, also recently achieved a record measurement on a standard pure-niobium cavity. By putting the cavity through a particular polishing and baking regimen, he achieved a lower surface resistance at 1.6 K than previously observed. This lower resistance helps increase the cavities' Q.

"There is still a lot to do to improve bulk niobium technology," Romanenko said. "My recent results with bulk niobium show that very simple twists to already existing processing recipes can lower the surface resistance dramatically and help cut down the costs, especially for continuous-wave machines."

Researchers are developing machines that run continuous-wave beams, as contrasted with pulsed beams, for future accelerators such as Berkeley Laboratory's Next-Generation Light Source and Fermilab's proposed Project X. CW accelerators require a good deal of power. With increased Q, cavities use less power and therefore require less refrigeration, helping save financial resources.

While pure niobium continues to be a promising material for superconducting cavities, Grassellino wanted to see what she could do with a new, different superconductor, so she worked with Allan Rowe and Mayling Wong-Squires of the SRF processing group. Together, they succeeded in producing a cavity with the new Q.

"The amazing thing is that this is our result on the first shot," she said. "For many years, people tried to get good results with niobium nitride, but they succeeded only partially."

Though researchers were previously able to achieve intriguing results above 4.2 Kelvin, they seemed to hit a wall when the temperature dropped below 4.2 K. The new Fermilab measurement shows instead almost zero surface resistance as the temperature approaches 1.6 K.

"Anna's got impressive first results. It's a great first step toward technology achievements for CW projects around the globe," said SRF Development Department Head Slava Yakovlev, who initiated the Q-maximization program.

"It's only by doing new R&D and getting out of our 'safe mode' that we can obtain extraordinary results to build what would otherwise be cost-prohibitive machines," Grassellino said. "A big acknowledgment goes to the SRF Development and Test and Instrumentation Departments. We thank those whose support has made these results possible."

Leah Hesla


University of Chicago geneticist discusses epigenetics next week

Could our environment affect how we pass on our genes? Photo: Stephen Barnett

Epigenetics is the emerging branch of science aimed at understanding how environmental influences such as diet and stress can act on an organism at the level of controlling gene activity and how these environmentally induced changes may be inherited by offspring.

On Friday, Sept. 7, at 8 p.m. in Ramsey Auditorium, University of Chicago geneticist Alex Ruthenburg will give a lecture on the development of the concept of epigenetics as part of the Fermilab Lecture Series. His talk will cover several areas where epigenetic information carriers are known to function, reveal what researchers in the field have discovered and are still wrestling with about the mechanism and conclude with connections between these molecular players and human health.

Until recently, Ruthenberg says, epigenetics was a catchall term for everything we do not yet understand about heredity beyond the double helix of DNA, a murky backwater of exceptions to the standard rules of genetics. New research is beginning to shed light on these puzzling phenomena. What we have learned thus far suggests that these epigenetic pathways may be far more general and central to genome management than imagined.

Admission to the lecture is $7.

Learn more.

Result of the Week

The march to higher and higher precision

The figure shows the agreement between the data and the CDF simulation for the electron transverse energy distribution. The electrons come from the decay of a Z particle.

Z bosons are produced at the Tevatron via the collision of particles – quarks and gluons – inside the proton and antiproton beams. Interactions within the collision can kick the Z boson in directions transverse to the direction of the incoming particle beamline. These kicks range from the very gentle, where the Z boson is moving along the beamline, to the very hard, where the Z boson emerges at large angles and velocities. The details of the collision physics from the very gentle to the very hard kicks are quite different. The study and understanding of these details require precise measurements. One needs a careful understanding of both the detector acceptance and the event selection efficiency. The top figure shows that the data and our simulation are in excellent agreement.

CDF physicists from the University of Rochester, using a sample of 140,000 Z bosons, have measured the momentum distribution of the Z boson in the direction transverse to the beamline to learn more about the physics of collisions that produce Z bosons. The Standard Model of particle physics is very successful in predicting many aspects of proton and antiproton collisions. However, because of the changing nature of the physics from low transverse momentum (gentle kicks) to high transverse momentum (hard kicks), no single Standard Model prediction is reliable and accurate at all transverse momenta. The prediction at low transverse momentum is very challenging as the physics there is complex. A widely used prediction program is RESBOS.

The Z boson transverse momentum distribution is a benchmark measurement. A precise measurement of this is needed to guide and refine predictions using the Standard Model. In the upper right insert in the second figure, one sees the precision of the data and its agreement with the RESBOS calculation in the low transverse momentum region. This knowledge of understanding the transverse momentum distribution can be applied to the production of other particles at both the Tevatron and LHC. It is important for any physics measurement because particles of interest are predominantly produced at low transverse momentum.

Learn more

—edited by Andy Beretvas

The plot is proportional to the probability for the process (Z → e+ e-) as a function of the transverse momentum. The black crosses are the data and the red histogram is the RESBOS calculation.
These CDF physicists contributed to this data analysis. From left: Arie Bodek, Jiyeon Han and Willis Sakumoto (all from the University of Rochester).
Special Announcement

Road D closed starting Sept. 4

Due to the construction of the IARC Office Technical and Educational building, part of Road D will be closed from Sept. 4 to mid-October.

See this map to view the detour route.


Chez Leon open on Sept. 5

In yesterday's issue of Fermilab Today, we erroneously stated that Chez Leon was closed on Wednesday, Sept. 5. It will in fact be open that day.

We regret the error.

In the News

After the Higgs: the new particle landscape

From Nature, Aug. 29, 2012

When particle physicists around the world woke up on 5 July, the scenes of joy, relief and tears were still fresh in their minds — along with a huge unanswered question. The memories were of celebrations the previous day, when researchers announced that a new particle very much like the long-sought Higgs boson had at last been found in data from the Large Hadron Collider (LHC) at CERN, Europe's particle-physics laboratory outside Geneva in Switzerland. The question promised to define their discipline's whole future. Is the particle a Higgs boson of maximum simplicity, as predicted by the 40-year-old standard model of particle physics? Or is it something more complex and interesting that will point towards a deeper, more complete theory?

Physicists hope and expect that the LHC will give them some answers over the next few years. But they are already honing their sales pitches for a machine to follow the LHC — a 'Higgs factory' that would illuminate such a theory with measurements far more precise than the LHC can provide.

Read more

Scottish country dancing in Ramsey Auditorium - through Aug. 31

International Folk Dancing in Ramsey Auditorium - through August

Free Weight Management class - begins Sept. 6

Walk 2 Run - begins Sept. 6

Fermilab Arts & Lecture Series: Epigenetics - Sept. 7

Fermilab Arts & Lecture Series: Broadway's Next H!T Musical - Sept. 22

Word 2010 classes scheduled

Excel 2010 classes scheduled

Access 2010 classes scheduled

Additional professional development courses

Bowlers wanted for 2012/2013 season

Outdoor soccer - Tuesdays and Thursdays at 6 p.m.

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