Thursday, Oct. 8, 2015
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Powerful pair of speakers scheduled for Oct. 12, 19

Fermi Society of Philosophy, A. Burov, "A Puzzling Error of Karl Popper," WH4NW - today

Muscle Toning registration due today

Barn Dance Oct. 11

Zumba Toning registration due Oct. 13

Process Piping Design; Process Piping, Material, Fabrication, Examination, Testing - Oct. 13-16

English country dancing Oct. 25 at Kuhn Barn and special workshop Oct. 15

Concert of Sator Duo at Kuhn Village Barn - Oct. 21

PowerPoint 2013: Introduction / Intermediate - Nov. 18

Mac OS X Mountain Lion (10.8) end of life - Dec. 14

Professional and Organization Development 2015-16 fall/winter course schedule

Scheduling a meeting with the Visa Office

FY 2017 diversity visa lottery registration open

Indoor soccer

Scottish country dancing Tuesdays evenings at Kuhn Barn

International folk dancing Thursday evenings at Kuhn Barn

Norris Recreation Center employee discount


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Dan Bauer leads SuperCDMS as new spokesperson

Dan Bauer

The Cryogenic Dark Matter Search has gone through a number of major changes over the years. In 2002, operations moved from Stanford University to the Soudan Mine in Minnesota. In 2010, the CDMS collaboration installed more advanced germanium detectors and renamed itself SuperCDMS.

And in 2019, the experiment will begin a new phase in the underground Canadian laboratory SNOLAB.

Fermilab scientist Dan Bauer will lead the SuperCDMS collaboration through this upcoming transition as its recently elected spokesperson. He began his three-year term in May, taking over from Blas Cabrera of Stanford University. Prior to his role as spokesperson, Bauer served CDMS and SuperCDMS as project manager and project scientist for 13 years.

SuperCDMS is one of several experiments around the world that is on the hunt for dark matter, hypothesized invisible stuff that holds galaxies together. SuperCDMS' goal is to detect it in the form of WIMPs: weakly interacting massive particles. The experiment will focus particularly on light WIMPS, with masses less than 10 times the mass of the proton.

Bauer's main goal is to make sure the move to SNOLAB, whose cleaner environment and greater depth beneath ground will help reduce backgrounds in the experiment, goes off smoothly.

It's not a matter of popping the experiment on a truck and sending it on its way to Ontario. One major piece of the transition is building a considerably larger, more complicated cryogenic system to lower the sensors' temperature from 50 millikelvin, their temperature in Soudan, to a mere 15 millikelvin. Colder sensors and improved shielding will allow the detectors to be more sensitive to potential dark matter interactions.

"We've been doing a lot of physics at Soudan, and switching to a new site is always a challenge," Bauer said. "We want to be set up to do the best possible experiment at SNOLAB."

Bauer is working to add new institutions to the collaboration, including SNOLAB. He is also in discussions with members of two similar experiments in Europe (Edelweiss and CRESST) to bring their detectors to SuperCDMS SNOLAB.

The SuperCDMS collaboration currently has members from 21 institutions, including SLAC National Accelerator Laboratory (the project managing institution), Pacific Northwest National Laboratory, U.S. and Canadian universities, a group in the UK, and NISER in India.

"I'm looking forward to building a new experiment — that's always fun," Bauer said. "Seeing dark matter particles for the first time would be fantastic."

Leah Hesla

In the News

Supernova 'stream' in neutrino lab's sights

From BBC News, Oct. 2, 2015

A global collaboration will aim to unravel the mysteries of neutrinos — also known as "ghost particles".

Among the goals of the venture, formed earlier this year, will be to catch neutrino particles streaming towards us from a supernova — an exploding star.

Such events occur about every 30 years, but the neutrino streams they produce have not been studied in detail.

Dune (Deep Underground Neutrino Experiment) will be hosted at Fermilab in Batavia, Illinois.

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In the News

Inaugural American Physical Society Division of Particles and Fields Instrumentation Award

From, Oct. 5, 2015

The inaugural American Physical Society (APS) Division of Particles and Fields Instrumentation Award has been presented jointly to David Nygren of the University of Texas at Arlington and Veljko Radeka of the U.S. Department of Energy's (DOE) Brookhaven National Laboratory. Nygren and Radeka received the award during the APS "New Technologies for Discovery" Workshop on October 5, 2015, at the University of Texas at Arlington.

The award citation notes that Nygren and Radeka were honored "for widespread contributions and leadership in the development of new detector technologies and low-noise electronics instrumentation in particle physics as well as other fields, and in particular work leading to the development and instrumentation of large volume liquid argon time projection chambers that are now a key element in the global particle physics program.

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Physics in a Nutshell

Is the universe getting bigger or am I getting smaller?

Alice knows she's getting bigger only because the room isn't.

It is a well-established fact that the universe is expanding. It grows without center, like an inflating raisin cake, but an infinite raisin cake filling all of space in all directions. The raisins are the galaxies.

A problem I've had with this explanation is that if everything were to double in size — galaxies, houses, you and me, rulers — then we'd never notice. I might be a towering giant, but if the room is equally huge, I wouldn't know. We can only see relative differences in sizes.

When scientists say the universe is expanding, they don't mean that its occupants are expanding along with it. The raisins do not grow with the cake. Imagine cake batter so full of raisins that they're pressed against each other when you first put the cake in the oven, but by the time it's done, there's only one raisin per mouthful. This would be a better analogy, but it raises another question: How do we know the raisins aren't shrinking?

Putting the question another way, what if the distances between galaxies are fixed, but everything except those distances are getting smaller? Or somewhere in between — the universe grows a little while we shrink a little. For that matter, where should we put the boundary line between the scales that grow relative to the scales that shrink?

Fundamentally, the expansion of the universe is described by one ratio that relates lengths in space with durations in time, sometimes called the cosmic scale factor. As time passes, this ratio changes: the scale of space increases with each second. But since this ratio, length divided by time, is a speed, suppose we think of space as fixed and all speeds slowing down.

What would happen if every object, from particles to planets, suddenly slowed down? Planets would fall in closer to the sun because they would have less angular momentum. Similarly, electrons would get closer to the nuclei of atoms. Molecular bonds would shorten. Every system bound by a force would shrink, but the distances between unconnected systems would stay the same.

Alternatively, what would happen if particle speeds were left alone but everything expanded uniformly, like a plate of marshmallows in the microwave? Again, electron and planetary orbits would then shrink to their natural sizes, like marshmallows taken out of the microwave, but the gaps between them wouldn't.

Regardless of how we interpret the underlying theory, we have the same picture: Distances between bound systems increase relative to the sizes of those systems. But that shouldn't be a surprise, since we're talking about the same physics theory in two different ways. It's all a matter of perspective.

Jim Pivarski

Photo of the Day

Tiny turtle

nature, animal, reptile, turtle, snapping turtle
A baby snapping turtle walks on the pedestrian path leading to Wilson Hall. Photo: Chris Sheppard, CCD
In the News

4,850 feet below: the hunt for dark matter

From Science Friday, Oct. 5, 2015

Deep in an abandoned gold mine in rural South Dakota, a team of physicists are hunting for astrophysical treasure. Their rare and elusive quarry is dark matter, a theoretical particle which has never been seen or directly detected. Yet its gravitational effect on distant galaxies hints at its existence and provides ample evidence to fuel the experiments and aspirations of scientists at the Sanford Underground Research Facility. Insulated by 4,850 feet of rock, the researchers have constructed the world's most sensitive particle detector, known as the Large Underground Xenon Experiment, or "LUX." Their goal is to use this complex device to capture an epiphanous event: the interaction between dark matter and atoms inside a chilled tank of liquid xenon. If they're successful, the researchers may not only solve some of the biggest mysteries in astrophysics but affirm their faith in the nature of dark matter.

Watch the video