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Einstein’s most famous equation

Friday, March 13th, 2015

This article appeared in symmetry on March 12, 2015.

You’ve heard of Einstein’s E=mc2, but what does it mean?

You’ve heard of Einstein’s E=mc2, but what does it mean?

With Einstein’s birthday just around the corner on March 14 (which also happens to be Pi Day), it seems appropriate to take a fresh look at one of his biggest accomplishments with a short video.

In 1905, Einstein published four papers that radically changed how we look at the world around us. Dubbed Einstein’s “Annus Mirabilis,” or “Year of Wonders,” it gave us revolutionary new ideas about light, atoms and how your frame of reference makes a big difference in your perception.

It was Einstein’s final paper that year that really took the (birthday) cake. In it, he gave us a deceptively simple idea—that mass and energy were equivalent. He even summed it up for us with the tiny equation E=mc2*.

However, while appearing simple, the implications of E=mc2 are huge and far-reaching. To find out why, sit back, enjoy some birthday cake (or pie, depending on how you’re celebrating), and watch the video!

*Although we are most familiar with E=mc2, Einstein didn’t quite say it that way in the original paper. It was actually in the form of a sentence in German: “If a body gives off the energy L in the form of radiation, its mass diminishes by L/V2.”

Chris Smith

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Scientists find rare dwarf satellite galaxy candidates in Dark Energy Survey data

Tuesday, March 10th, 2015

This Fermilab press release came out on March 10, 2015.

 

 

Scientists on two continents have independently discovered a set of celestial objects that seem to belong to the rare category of dwarf satellite galaxies orbiting our home galaxy, the Milky Way.

Dwarf galaxies are the smallest known galaxies, and they could hold the key to understanding dark matter and the process by which larger galaxies form.

A team of researchers with the Dark Energy Survey, headquartered at the U.S. Department of Energy’s Fermi National Accelerator Laboratory, and an independent group from the University of Cambridge jointly announced their findings today. Both teams used data taken during the first year of the Dark Energy Survey, all of which is publicly available, to carry out their analysis.

“The large dark matter content of Milky Way satellite galaxies makes this a significant result for both astronomy and physics,” said Alex Drlica-Wagner of Fermilab, one of the leaders of the Dark Energy Survey analysis.

Satellite galaxies are small celestial objects that orbit larger galaxies, such as our own Milky Way. Dwarf galaxies can be found with fewer than 100 stars and are remarkably faint and difficult to spot. (By contrast, the Milky Way, an average-sized galaxy, contains billions of stars.)

These newly discovered objects are a billion times dimmer than the Milky Way and a million times less massive. The closest of them is about 100,000 light-years away.

“The discovery of so many satellites in such a small area of the sky was completely unexpected,” said Cambridge’s Institute of Astronomy’s Sergey Koposov, the Cambridge study’s lead author. “I could not believe my eyes.”

Scientists have previously found more than two dozen of these satellite galaxies around our Milky Way. About half of them were discovered in 2005 and 2006 by the Sloan Digital Sky Survey, the precursor to the Dark Energy Survey. After that initial explosion of discoveries, the rate fell to a trickle and dropped off entirely over the past five years.

The Dark Energy Survey is looking at a new portion of the southern hemisphere, covering a different area of sky than the Sloan Digital Sky Survey. The galaxies announced today were discovered in a search of only the first of the planned five years of Dark Energy Survey data, covering roughly one-third of the portion of sky that DES will study. Scientists expect that the full Dark Energy Survey will find up to 30 of these satellite galaxies within its area of study.

graphic

Download: Med-res | Low-res

This illustration maps out the previously discovered dwarf satellite galaxies (in blue) and the newly discovered candidates (in red) as they sit outside the Milky Way. Image: Yao-Yuan Mao, Ralf Kaehler, Risa Wechsler (KIPAC/SLAC).

 

 

Atlas image obtained as part of the Two Micron All Sky Survey (2MASS), a joint project of the University of Massachusetts and the Infrared Processing and Analysis Center/California Institute of Technology, funded by the National Aeronautics and Space Administration and the National Science Foundation.

While more analysis is required to confirm any of the observed celestial objects as satellite galaxies, researchers note their size, low surface brightness and significant distance from the center of the Milky Way as evidence that they are excellent candidates. Further tests are ongoing, and data collected during the second year of the Dark Energy Survey could yield more of these potential dwarf galaxies to study.

Newly discovered galaxies would also present scientists with more opportunities to search for signatures of dark matter. Dwarf satellite galaxies are dark matter-dominated, meaning they have much more mass in unseen matter than in stars. The nature of this dark matter remains unknown but might consist of particles that annihilate each other and release gamma rays. Because dwarf galaxies do not host other gamma ray sources, they make ideal laboratories to search for signs of dark matter annihilation. Scientists are confident that further study of these objects will lead to even more sensitive searches for dark matter.

In a separate result also announced today, the Large Area Telescope Collaboration for NASA’s Fermi Gamma-Ray Telescope mission reported that they did not see any significant excess of gamma ray emission associated with the new Dark Energy Survey objects. This result demonstrates that new discoveries from optical telescopes can be quickly translated into tests of fundamental physics.

“We did not detect significant emission with the LAT, but the dwarf galaxies that DES has and will discover are extremely important targets for the dark matter search,” said Peter Michelson, spokesperson for the LAT collaboration. “If not leading to an identification of particle dark matter, they will certainly be useful to constrain its properties.”

The Dark Energy Survey is a five-year effort to photograph a large portion of the southern sky in unprecedented detail. Its primary instrument is the Dark Energy Camera, which – at 570 megapixels – is the most powerful digital camera in the world, able to see galaxies up to 8 billion light-years from Earth. Built and tested at Fermilab, the camera is now mounted on the 4-meter Victor M. Blanco telescope at the Cerro Tololo Inter-American Observatory in the Andes Mountains in Chile.

The survey’s five-year mission is to discover clues about the nature of dark energy, the mysterious force that makes up about 70 percent of all matter and energy in the universe. Scientists believe that dark energy may be the key to understanding why the expansion of the universe is accelerating.

“The Dark Energy Camera is a perfect instrument for discovering small satellite galaxies,” said Keith Bechtol of the Kavli Institute for Cosmological Physics at the University of Chicago, who helped lead the Dark Energy Survey analysis. “It has a very large field of view to quickly map the sky and great sensitivity, enabling us to look at very faint stars. These results show just how powerful the camera is and how significant the data it collects will be for many years to come.”

The Dark Energy Survey analysis is available here. The University of Cambridge analysis is available here.

The Dark Energy Survey is a collaboration of more than 300 scientists from 25 institutions in six countries. For more information about the survey, please visit the experiment’s website.

Funding for the DES Projects has been provided by the U.S. Department of Energy, the U.S. National Science Foundation, the Ministry of Science and Education of Spain, the Science and Technology Facilities Council of the United Kingdom, the Higher Education Funding Council for England, the National Center for Supercomputing Applications at the University of Illinois at Urbana-Champaign, the Kavli Institute of Cosmological Physics at the University of Chicago, Financiadora de Estudos e Projetos, Fundação Carlos Chagas Filho de Amparo à Pesquisa do Estado do Rio de Janeiro, Conselho Nacional de Desenvolvimento Científico e Tecnológico and the Ministério da Ciência e Tecnologia, the Deutsche Forschungsgemeinschaft and the collaborating institutions in the Dark Energy Survey. The DES participants from Spanish institutions are partially supported by MINECO under grants AYA2012-39559, ESP2013-48274, FPA2013-47986 and Centro de Excelencia Severo Ochoa SEV-2012-0234, some of which include ERDF funds from the European Union.

Fermilab is America’s premier national laboratory for particle physics and accelerator research. A U.S. Department of Energy Office of Science laboratory, Fermilab is located near Chicago, Illinois, and operated under contract by the Fermi Research Alliance, LLC. Visit Fermilab’s website at www.fnal.gov and follow us on Twitter at @Fermilab.

The DOE Office of Science is the single largest supporter of basic research in the physical sciences in the United States and is working to address some of the most pressing challenges of our time. For more information, please visit science.energy.gov .

The mission of the University of Cambridge is to contribute to society through the pursuit of education, learning and research at the highest international levels of excellence. To date, 90 affiliates of the university have won the Nobel Prize. Founded in 1209, the university comprises 31 autonomous colleges, which admit undergraduates and provide small-group tuition, and 150 departments, faculties and institutions. Cambridge is a global university. Its 19,000 student body includes 3,700 international students from 120 countries. Cambridge researchers collaborate with colleagues worldwide, and the university has established larger-scale partnerships in Asia, Africa and America. The university sits at the heart of one of the world’s largest technology clusters. The ‘Cambridge Phenomenon’ has created 1,500 hi-tech companies, 14 of them valued at over US$1 billion and two at over US$10 billion. Cambridge promotes the interface between academia and business and has a global reputation for innovation. www.cam.ac.uk .

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Detecting something with nothing

Tuesday, March 3rd, 2015

This article appeared in Fermilab Today on March 3, 2015.

From left: Jason Bono (Rice University), Dan Ambrose (University of Minnesota) and Richie Bonventre (Lawrence Berkeley National Laboratory) work on the Mu2e straw chamber tracker unit at Lab 3. Photo: Reidar Hahn

From left: Jason Bono (Rice University), Dan Ambrose (University of Minnesota) and Richie Bonventre (Lawrence Berkeley National Laboratory) work on the Mu2e straw chamber tracker unit at Lab 3. Photo: Reidar Hahn

Researchers are one step closer to finding new physics with the completion of a harp-shaped prototype detector element for the Mu2e experiment.

Mu2e will look for the conversion of a muon to only an electron (with no other particles emitted) — something predicted but never before seen. This experiment will help scientists better understand how these heavy cousins of the electron decay. A successful sighting would bring us nearer to a unifying theory of the four forces of nature.

The experiment will be 10,000 times as sensitive as other experiments looking for this conversion, and a crucial part is the detector that will track the whizzing electrons. Researchers want to find one whose sole signature is its energy of 105 MeV, indicating that it is the product of the elusive muon decay.

In order to measure the electron, scientists track the helical path it takes through the detector. But there’s a catch. Every interaction with detector material skews the path of the electron slightly, disturbing the measurement. The challenge for Mu2e designers is thus to make a detector with as little material as possible, says Mu2e scientist Vadim Rusu.

“You want to detect the electron with nothing — and this is as close to nothing as we can get,” he said.

So how to detect the invisible using as little as possible? That’s where the Mu2e tracker design comes in. Panels made of thin straws of metalized Mylar, each only 15 microns thick, will sit inside a cylindrical magnet. Rusu says that these are the thinnest straws that people have ever used in a particle physics experiment.

These straws, filled with a combination of argon and carbon dioxide gas and threaded with a thin wire, will wait in vacuum for the electrons. Circuit boards placed on both ends of the straws will gather the electrical signal produced when electrons hit the gas inside the straw. Scientists will measure the arrival times at each end of the wire to help accurately plot the electron’s overall trajectory.

“This is another tricky thing that very few have attempted in the past,” Rusu said.

The group working on the Mu2e tracker electronics have also created the tiny, low-power circuit boards that will sit at the end of each straw. With limited space to run cooling lines, necessary features that whisk away heat that would otherwise sit in the vacuum, the electronics needed to be as cool and small as possible.

“We actually spent a lot of time designing very low-power electronics,” Rusu said.

This first prototype, which researchers began putting together in October, gives scientists a chance to work out kinks, improve design and assembly procedures, and develop the necessary components.

One lesson already learned? Machining curved metal with elongated holes that can properly hold the straws is difficult and expensive. The solution? Using 3-D printing to make a high-tech, transparent plastic version instead.

Researchers also came up with a system to properly stretch the straws into place. While running a current through the straw, they use a magnet to pluck the straw — just like strumming a guitar string — and measure the vibration. This lets them set the proper tension that will keep the straw straight throughout the lifetime of the experiment.

Although the first prototype of the tracker is complete, scientists are already hard at work on a second version (using the 3D-printed plastic), which should be ready in June or July. The prototype will then be tested for leaks and to see if the electronics pick up and transmit signals properly.

A recent review of Mu2e went well, and Rusu expects work on the tracker construction to begin in 2016.

Lauren Biron

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Ten unusual detector materials

Tuesday, February 17th, 2015

This article appeared in symmetry on Feb. 17, 2015.

The past century has generated some creative ideas for tracking particles. Image: Sandbox Studio

The past century has generated some creative ideas for tracking particles. Image: Sandbox Studio

Hans had been waiting in the darkened room for 45 minutes. It was a dull part of his day, but acclimating his eyes was a necessary part of his experiment—counting faint sparkles of light caused by alpha particles deflecting off a thin metal foil.

The experiment was part of a series organized by Ernest Rutherford in 1908, and it led to the discovery of the atomic nucleus. Rutherford’s assistant, physicist Hans Geiger, would share credit for the discovery.

Their experiment was particle physics in its infancy.

Studying particle physics requires revealing the smallest bits of matter. This work might involve hurling billions of accelerated particles at a target and watching for the flash of energy that results from the crash. It might involve setting up a detector to wait for particles created in nature to pass through.

Over the years, electronics and mainframe computers have taken over Rutherford and Geiger’s painstaking particle-counting duties. And physicists have used a host of materials other than foil to lure those particles—including hard-to-catch neutrinos—into view.

1. Dry cleaning fluid.

Physicist Ray Davis had either a terrific idea for a particle detector or a tremendous load of laundry. In a few years leading up to 1966, he obtained 600 tons of a common dry cleaning solvent, perchloroethylene, and deposited it nearly a mile beneath the Black Hills of South Dakota in a detector stationed in the Homestake gold mine. He hoped to count solar neutrinos, which trigger a detectable chemical reaction when they pass through this fluid. Davis’ perchloroethylene-filled particle detector was a success, even though he tallied only a third of the neutrinos he was expecting. Revelations that neutrinos change form as they travel were soon to follow.

2. Soviet-era artillery shells.

In the 1940s, the Russian navy armed its vessels with a grade of brass specifically designed to hold its shape under extreme stress and for long periods of time. More than 50 years later, the CMS particle detector under construction at the Large Hadron Collider at CERN required brass with the same high standards. It needed to be able to withstand a bombardment of particles with unflinching consistency over its lifetime. The lab struck a deal with Russian officials to melt down old, unused shells for the CMS hadron calorimeter, a part of the detector that measures the energy of particles produced in collisions in the LHC.

3. 2.5 million gallons of mineral oil.

Fermilab’s 14,000-ton NOvA neutrino detector in northern Minnesota, possibly the largest freestanding plastic structure in the world, is filled with a liquid substance that is 95 percent mineral oil. That single raw material took up 108 rail cars and a barge as it left a refinery in southwest Louisiana for a facility 1000 miles away near Chicago, where it was blended with the remaining ingredients 110,000 gallons at time. The result was a liquid scintillator, which releases measurable light as a result of collisions between neutrinos and particles in the liquid.

4. Lead bricks wrapped in foil by robots.

The OPERA detector at Gran Sasso National Laboratory catches neutrinos with something a bit more, as they say in Italy, duro—a wall of 150,000 18-pound bricks. The bricks themselves are stacks of lead sheets and radiation-sensitive film, wrapped in reflective aluminum tape and sealed in an airtight container. When neutrinos collide with the lead, they create other particles that streak across the film and leave tracks that can be analyzed after the film is developed. The 11 robots of Gran Sasso’s brick-assembly machine, otherwise known as BAM, cranked out 750 bricks per day, faster and with much less complaining than an army of graduate students.

5. Smartphones. Yep, there’s an app for that.

Actually, there are at least two. A physicist at the University of Wisconsin, Madison, and a director of citizen science at the LA Makerspace are working on one called DECO, an educational app that records speedy cosmic-ray particles that your phone’s camera accidentally detects. Two more physicists, one from University of California, Irvine, and the other from University of California, Davis, are at work on a similar app called CRAYFIS. Their objective: gather enough users to create a functional cosmic ray detector from a massive network of devices.

6. A crystal ball.

No, SLAC National Accelerator Laboratory did not enlist a psychic medium to locate subatomic particles when they built the Crystal Ball detector in the late ’70s. They did, however, arrange more than 600 sodium iodide crystals into a sphere 13 ½ feet around to detect neutral particles at the SPEAR particle collider. The crystals work in similar fashion to the liquid inside the NOvA detector (see No. 2 in this list), converting energy from particle collisions to measurable light. The detector is still in use, currently at Johannes Gutenberg University in Mainz, Germany. Its future, ironically, is uncertain.

7. Antarctica, from below.

When penguins look down, there’s a chance they might discover one of 86 holes drilled more than a mile deep into the Antarctic ice for the IceCube experiment. When turbocharged cosmic neutrinos collide with ice, the resulting particle shrapnel creates a blue flash of light otherwise known as Cherenkov light. Scientists survey the ice sheet for that light with an array of more than 5000 separate, bauble-like detectors strung on wires running down each hole.

8. Antarctica, from above.

Should penguins look up instead, they may spot the Antarctic Impulsive Transient Antenna, or ANITA, floating above them, suspended from a massive scientific balloon. ANITA listens for radio waves emanating from the ice below. The pure, polar ice makes an unbelievably clear medium for the Askaryan effect, discovered only in 2000, in which cosmic neutrinos similar to the ones that produce light for the IceCube experiment generate a signature radio signal. The floating antenna is so sensitive that it can detect a handheld radio up to 400 miles away.

9. A breath of fresh Martian air.

Our descendants may well enjoy a beautiful sunset on Mars—if we can engineer its atmosphere to warm the planet from its current average temperature of about minus 60 degrees Celsius to something more friendly to vacationing humans. For such a project, some researchers have singled out the compound octofluoropropane as the greenhouse gas of choice. In the meantime, researchers on the PICO experiment at underground Canadian laboratory SNOLAB are using octofluoropropane in its liquid state to detect dark matter. If a particle of dark matter can knock one fluorine nucleus hard enough, it will cause the superheated liquid to boil and form a telltale bubble in the chamber.

10. Dry ice, alcohol and a fish tank.

This one you can build yourself. The cloud chamber earned its inventor the 1927 Nobel Prize in physics, and variations of it—including No. 9 on this list— have a long history of use in particle physics labs. But many DIY varieties exist online, too. The gist is usually to create a thick vapor (of alcohol) that is cooled (by dry ice). Be patient, and you’ll catch a passing particle such as a cosmic muon as it bumps into vapor molecules and triggers a cloudy streak of condensation through the chamber (a.k.a. fish tank).

 

Troy Rummler

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Fermilab contributes to SLAC LCLS-II with cutting-edge technology and expertise

Wednesday, February 11th, 2015

This article appeared in Fermilab Today on Feb. 11, 2015.

Fermilab is developing superconducting accelerating cavities similar to this one for SLAC's Linac Coherent Light Source II. Photo: Reidar Hahn

Fermilab is developing superconducting accelerating cavities similar to this one for SLAC’s Linac Coherent Light Source II. Photo: Reidar Hahn

Now one year into its five-year construction plan, the Linac Coherent Light Source II, an electron accelerator project at SLAC, will produce a high-power free-electron laser for cutting-edge scientific explorations ranging from refined observations of molecules and cellular interactions to innovative materials engineering. Cornell University as well as Argonne National Laboratory, Lawrence Berkeley National Laboratory, Fermilab and Thomas Jefferson National Accelerator Facility are partners in the SLAC-directed project.

“We at the laboratories are all developing close ties,” said Richard Stanek, Fermilab LCLS-II team leader. “The DOE science lab complex will be stronger for this collaboration.”

In 2015, Fermilab will intensify its LCLS-II contribution in the overlapping areas of superconducting radio-frequency (SRF) accelerator technology and cryogenics, critical components that distinguish LCLS-II from SLAC’s current LCLS facility, whose laser production has enabled noted scientific investigations in cancer treatment and other important areas.

SLAC physicist Marc Ross, LCLS-II cryogenics systems manager, said LCLS cannot keep up with scientists’ requests for use. The existing LCLS facility and LCLS-II combined will offer researchers laser X-rays with a wide range of properties.

“This new approach will transform the repetition rate of LCLS — from 120 pulses per second to up to 1 million per second,” Ross said. “This will allow a completely new class of experiments and, eventually, a much larger number of experimental stations operated in parallel.”

Fermilab Technical Division physicists Hasan Padamsee, division head, and Anna Grassellino and their team are working on SRF technology for LCLS-II, in particular on implementing Fermilab’s two recent findings to reduce the needed cryogenic power. In one innovation, known as nitrogen doping, Grassellino found that infusing a small amount of nitrogen gas when preparing the superconducting cavities — the structures through which beam is accelerated — reduces two main causes of the usually expected resistance to radio-frequency currents.

“It is exciting to see our discovery becoming an enabling technology for LCLS-II,” Grassellino said.

Grassellino’s high-Q team has also found that the cavities’ cooling dynamics significantly helps expel magnetic flux, another major source of cavity power dissipation. The Fermilab high-Q team, together with Cornell University and Jefferson Lab, are currently working on calibrating the cooling thermogradient for LCLS-II.

Stanek said Fermilab is advancing its SRF work with its LCLS-II participation.

“I see this project taking us from an R&D phase of SRF technology, which is where we have been the past six to eight years, and moving our expertise into production,” Stanek said. “This is a big step forward.”

Fermilab and Jefferson Lab are working closely together on the cooling systems that enable the cavities’ superconductivity. Fermilab scientist Camille Ginsburg leads LCLS-II cryomodule production at Fermilab, and Fermilab engineer Arkadiy Klebaner manages the LCLS-II cryomodules distribution system.

“To build a high-energy beam using SRF technology, LCLS-II needed expertise in cryogenics,” Klebaner said. “So Jefferson Lab and Fermilab, who both have special expertise in this, were ready to help out.”

A cryogenic plant generating the refrigeration, a cryogenic distribution system for transporting the refrigeration into cryomodules and the cryomodules themselves make up the LCLS-II cryogenics. Jefferson Lab will provide the cryogenic plant, and Fermilab is in charge of developing the cryogenic distribution system. Jefferson Lab and Fermilab are jointly developing LCLS-II’s 35 cryomodules, each one about 10 meters long.

Fermilab’s contribution draws on the Tevatron’s cryogenics and on SRF research begun for the proposed International Linear Collider. The lab’s LCLS-II experience will also help with developing its planned PIP-II accelerator.

“So when we build the next accelerator for Fermilab, PIP-II, then we will have already gotten a lap around the production race course,” Padamsee said.

All labs have something special to contribute to LCLS-II, Ross said.

“The Fermilab team have figured out a way to make this kind of accelerator much better operating in the cold temperature that superconducting technology requires,” Ross said. “It is worthy of special recognition.”

Rich Blaustein

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ELBNF is born

Tuesday, February 3rd, 2015

This article appeared in Fermilab Today on Jan. 27, 2015.

The proposed experiment at the Long-Baseline Neutrino Facility would send neutrinos through the Earth's mantle from Batavia, Illinois, to Lead, South Dakota. Image: symmetry

The proposed experiment at the Long-Baseline Neutrino Facility would send neutrinos through the Earth’s mantle from Batavia, Illinois, to Lead, South Dakota. Image: symmetry

At approximately 6:15 p.m. CST on Jan. 22, 2015, the largest and most ambitious experimental collaboration for neutrino science was born.

It was inspired by a confluence of scientific mysteries and technological advances, engendered by the P5 report and the European Strategy update, and midwifed by firm tugs from Fermilab, CERN and Brookhaven Lab. Going by the placeholder name ELBNF (Experiment at the Long-Baseline Neutrino Facility), the newborn had the impressive heft of 145 institutions from 23 countries.

The new Institutional Board (IB), convened by interim chair Sergio Bertolucci, unanimously approved a Memorandum of Collaboration that launches the election of spokespeople and a process to develop bylaws. The IB also endorsed an international governance plan for oversight of ELBNF detector projects, in concert with the construction of the LBNF facility hosted by Fermilab.

The goal of this international collaboration is crystal clear: a 40-kiloton modular liquid-argon detector deep underground at the Sanford Underground Research Facility exposed to a megawatt-class neutrino beam from Fermilab with the first 10 kilotons in place by 2021. This goal will enable a comprehensive investigation of neutrino oscillations that can establish the presence of CP violation for leptons, unequivocally determine the neutrino mass ordering and strongly test our current neutrino paradigm. A high-resolution near detector on the Fermilab site will have its own rich physics program, and the underground far detector will open exciting windows on nucleon decay, atmospheric neutrinos and neutrino bursts from supernova detonations.

Unlike most births, this one took place at an international meeting hosted by Fermilab; there was room for nearly all the friends and family of accelerator-based neutrino experiments. One of the critical items flagged at this meeting is to find a better name for the new collaboration. Here are a few of my unsolicited attempts:

nuLAND = neutrino Liquid ArgoN Detector

GOLDEN = Giant OsciLlation Detector Experiment for Neutrinos

Think you can do better? Go ahead. My older son, a high-priced management consultant, offered another one pro bono: NEutrino Research DetectorS.

I am too young to have been in the room when ATLAS and CMS (or for that matter CDF and DZero) came into being, but last week I had the thrill of being part of something that had the solid vibe of history being made. The meeting website is here.

Joe Lykken, Fermilab deputy director

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DECam’s nearby discoveries

Monday, February 2nd, 2015

This article appeared in symmetry on Jan. 22, 2015.

The Dark Energy Camera does more than its name would lead you to believe. Image courtesy of NOAO

The Dark Energy Camera does more than its name would lead you to believe. Image courtesy of NOAO

The Dark Energy Camera, or DECam, peers deep into space from its mount on the 4-meter Victor Blanco Telescope high in the Chilean Andes.

Thirty percent of the camera’s observing time—about 105 nights per year—go to the team that built it: scientists working on the Dark Energy Survey.

Another small percentage of the year is spent on maintenance and upgrades to the telescope. So who else gets to use DECam? Dozens of other projects share its remaining time.

Many of them study objects far across the cosmos, but five of them investigate ones closer to home.

Overall, these five groups take up just 20 percent of the available time, but they’ve already taught us some interesting things about our planetary neighborhood and promise to tell us more in the future.

Far-out asteroids

Stony Brook University’s Aren Heinze and the University of Western Ontario’s Stanimir Metchev used DECam for four nights in early 2014 to search for unknown members of our solar system’s main asteroid belt, which sits between Mars and Jupiter.

To detect such faint objects, one needs to take a long exposure. However, the paths of these asteroids lie close enough to Earth that taking an exposure longer than a few minutes results in blurred images. Heinze and Metchev’s fix was to stack more than 100 images taken in less than two minutes each.

With this method, the team expects to measure the positions, motions and brightnesses of hundreds of main belt asteroids not seen before. They plan to release their survey results in late 2015, and an early partial analysis indicates they’ve already found hundreds of asteroids in a region smaller than DECam’s field of view—about 20 times the area of the full moon.

Whole new worlds

Scott Sheppard of the Carnegie Institution for Science in Washington DC and Chad Trujillo of Gemini Observatory in Hilo, Hawaii, use DECam to look for distant denizens of our solar system. The scientists have imaged the sky for two five-night stretches every year since November 2012.

Every night, the DECam’s sensitive 570-megapixel eye captures images of an area of sky totaling about 200 to 250 times the area of the full moon, returning to each field of view three times. Sheppard and Trujillo run the images from each night through software that tags everything that moves.

“We have to verify everything by eye,” Sheppard says. So they look through about 60 images a night, or 300 total from a perfect five-night observing run, a process that gives them a few dozen objects to study at Carnegie’s Magellan Telescope.

The scientists want to find worlds beyond Pluto and its brethren—a region called the Kuiper Belt, which lies some 30 to 50 astronomical units from the sun (compared to the Earth’s 1). On their first observing run, they caught one.

This new world, with the catalog name of 2012 VP113, comes as close as 80 astronomical units from the sun and journeys as far as 450. Along with Sedna, a minor planet discovered a decade ago, it is one of just two objects found in what was once thought of as a complete no man’s land.

Sheppard and Trujillo also have discovered another dwarf planet that is one of the top 10 brightest objects beyond Neptune, a new comet, and an asteroid that occasionally sprouts an unexpected tail of dust.

Mythical creatures

Northern Arizona University’s David Trilling and colleagues used the DECam for three nights in 2014 to look for “centaurs”—so called because they have characteristics of both asteroids and comets. Astronomers believe centaurs could be lost Kuiper Belt objects that now lie between Jupiter and Neptune.

Trilling’s team expects to find about 50 centaurs in a wide range of sizes. Because centaurs are nearer to the sun than Kuiper Belt objects, they are brighter and thus easier to observe. The scientists hope to learn more about the size distribution of Kuiper Belt objects by studying the sizes of centaurs. The group recently completed its observations and plan to report them later in 2015.

Next-door neighbors

Lori Allen of the National Optical Astronomy Observatory outside Tucson, Arizona, and her colleagues are looking for objects closer than 1.3 astronomical units from the sun. These near-Earth objects have orbits that can cross Earth’s—creating the potential for collision.

Allen’s team specializes in some of the least-studied NEOs: ones smaller than 50 meters across.

Even small NEOs can be destructive, as demonstrated by the February 2013 NEO that exploded above Chelyabinsk, Russia. The space rock was just 20 meters wide, but the shockwave from its blast shattered windows, which caused injuries to more than 1000 people.

In 2014, Allen’s team used the DECam for 10 nights. They have 20 more nights to use in 2015 and 2016.

They have yet to release specific findings from the survey’s first year, but the researchers say they have a handle of the distribution of NEOs down to just 10 meters wide. They also expect to discover about 100 NEOs the size of the one that exploded above Chelyabinsk.

Space waste

Most surveys looking for “space junk”—inactive satellites, parts of spacecraft and the like in orbit around the Earth—can see only pieces larger than about 20 centimeters. But there’s a lot more material out there.

How much is a question Patrick Seitzer of the University of Michigan and colleagues hope to answer. They used DECam to hunt for debris smaller than 10 centimeters, or the size of a smartphone, in geosynchronous orbit.

The astronomers need to capture at least four images of each piece of debris to determine its position, motion and brightness. This can tell them about the risk from small debris to satellites in geosynchronous orbit. Their results are scheduled for release in mid-2015.

Liz Kruesi

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How to build your own particle detector

Wednesday, January 21st, 2015

This article ran in symmetry on Jan. 20, 2015

Make a cloud chamber and watch fundamental particles zip through your living room! Image: Sandbox Studio, Chicago

Make a cloud chamber and watch fundamental particles zip through your living room! Image: Sandbox Studio, Chicago

The scale of the detectors at the Large Hadron Collider is almost incomprehensible: They weigh thousands of tons, contain millions of detecting elements and support a research program for an international community of thousands of scientists.

But particle detectors aren’t always so complicated. In fact, some particle detectors are so simple that you can make (and operate) them in your own home.

The Continuously Sensitive Diffusion Cloud Chamber is one such detector. Originally developed at UC Berkeley in 1938, this type of detector uses evaporated alcohol to make a ‘cloud’ that is extremely sensitive to passing particles.

Cosmic rays are particles that are constantly crashing into the Earth from space. When they hit Earth’s atmosphere, they release a shower of less massive particles, many of which invisibly rain down to us.

When a cosmic ray zips through a cloud, it creates ghostly particle tracks that are visible to the naked eye.

Building a cloud chamber is easy and requires only a few simple materials and steps:

Materials:

  • Clear plastic or glass tub (such as a fish tank) with a solid lid (plastic or metal)
  • Felt
  • Isopropyl alcohol (90% or more. You can find this at a pharmacy or special order from a chemical supply company. Wear safety goggles when handling the alcohol.)
  • Dry ice (frozen carbon dioxide. Often used at fish markets and grocery stores to keep products cool. Wear thick gloves when handling the dry ice.)

Steps:

  1. Cut the felt so that it is the size of the bottom of the fish tank. Glue it down inside the tank (on the bottom where the sand and fake treasure chests would normally go).
  2. Once the felt is secured, soak it in the isopropyl alcohol until it is saturated. Drain off any excess alcohol.
  3. Place the lid on top of dry ice so that it lies flat. You might want to have the dry ice in a container or box so that it is more stable.
  4. Flip the tank upside down, so that the felt-covered bottom of the tank is on top, and place the mouth of the tank on top of the lid.
  5. Wait about 10 minutes… then turn off the lights and shine a flashlight into your tank.
Artwork by: Sandbox Studio, Chicago

What is happening inside your cloud chamber?

The alcohol absorbed by the felt is at room temperature and is slowly evaporating into the air. But as the evaporated alcohol sinks toward the dry ice, it cools down and wants to turn back into a liquid.

The air near the bottom of the tank is now supersaturated, which means that it is just below its atmospheric dew point. And just as water molecules cling to blades of grass on cool autumn mornings, the atmospheric alcohol will form cloud-like droplets on anything it can cling to.

Particles, coming through!

When a particle zips through your cloud chamber, it bumps into atmospheric molecules and knocks off some of their electrons, turning the molecules into charged ions. The atmospheric alcohol is attracted to these ions and clings to them, forming tiny droplets.

The resulting tracks left behind look like the contrails of airplane—long spindly lines marking the particle’s path through your cloud chamber.

What you can tell from your tracks?

Many different types of particles might pass through your cloud chamber. It might be hard to see, but you can actually differentiate between the types of particles based on the tracks they leave behind.

Short, fat tracks

Sorry—not a cosmic ray. When you see short, fat tracks, you’re seeing an atmospheric radon atom spitting out an alpha particle (a clump of two protons and two neutrons). Radon is a naturally occurring radioactive element, but it exists in such low concentrations in the air that it is less radioactive than peanut butter. Alpha particles spat out of radon atoms are bulky and low-energy, so they leave short, fat tracks.

Long, straight track

Congratulations! You’ve got muons! Muons are the heavier cousins of the electron and are produced when a cosmic ray bumps into an atmospheric molecule high up in the atmosphere. Because they are so massive, muons bludgeon their way through the air and leave clean, straight tracks.

Zig-zags and curly-cues

If your track looks like the path of a lost tourist in a foreign city, you’re looking at an electron or positron (the electron’s anti-matter twin). Electrons and positrons are created when a cosmic ray crashes into atmospheric molecules. Electrons and positrons are light particles and bounce around when they hit air molecules, leaving zig-zags and curly-cues.

Forked tracks

If your track splits, congratulations! You just saw a particle decay. Many particles are unstable and will decay into more stable particles. If your track suddenly forks, you are seeing physics in action!

 

 

Sarah Charley

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Deck the halls with Nobel physicists

Friday, December 19th, 2014

This article appeared in symmetry on Dec. 16, 2014.

Symmetry presents a physics twist on the craft of cutting paper snowflakes. Image: Sandbox Studio, Chicago

Symmetry presents a physics twist on the craft of cutting paper snowflakes. Image: Sandbox Studio, Chicago

If you’re looking for a way to decorate for the holidays while also proudly declaring your love of science, symmetry has got your back. Below you’ll find templates for paper snowflakes with winners of the Nobel Prize in Physics incorporated into the designs.

With the help of a printer, paper, an X-acto knife (preferably with some sharp replacement blades at the ready) and a cutting board or mat, you can transform your home into a flurry of famous physicists.

Simply download the snowflake templates, print them out, follow the folding instructions, and cut out the gray areas, making sure to cut through every layer of paper (but not your fingers!). Then unfold the paper and revel in your creation.

Practice makes perfect, but remember, no two snowflakes are supposed to be alike anyway.

Albert Einstein

Energy and mass may be equivalent, but this Albert Einstein snowflake is beyond compare.

SnowflakeEinstein2

Download PDF template.

 

Marie Curie

Double Nobel Laureate Marie Curie radiates charm in this snowflake design.

Download PDF template.

 

Erwin Schrödinger

Is it an Erwin Schrödinger snowflake with cats on it, or is it a cat snowflake with Erwin Schrödingers on it? You won’t know until you make it.

Download PDF template.

For advanced snowflake-making techniques, see our instructional video.

Kathryn Jepsen

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New books for the physics fan

Saturday, December 13th, 2014

This article appeared in symmetry on Dec. 9, 2014.

These recently published popular science books will help you catch up on particle physics news, knowledge and history. Image: Artwork Sandbox Studio, Chicago, with Ana Kova

These recently published popular science books will help you catch up on particle physics news, knowledge and history. Image: Artwork Sandbox Studio, Chicago, with Ana Kova

Looking to stay current on your particle physics knowledge? Here are 10 recent popular science books you might want to check out.

 

1. Faraday, Maxwell and the Electromagnetic Field: How Two Men Revolutionized Physics

Nancy Forbes, Basil Mahon

Classical unified field theory came from the realization that electricity, magnetism and light all can be explained with a single electromagnetic field.

There is no modern physics without classical unified field theory—heck, there are no electronics without classical unified field theory—and there is no classical unified field theory without Michael Faraday (1791-1867) and James Clerk Maxwell (1831-1879).

The unlikely partners, born four decades apart, shared the achievement of upending a view of the world that had prevailed since Isaac Newton.

“The extraordinary idea put forward by Faraday and Maxwell was that space itself acted as a repository of energy and a transmitter of forces,” write Nancy Forbes and Basil Mahon in Faraday, Maxwell and the Electromagnetic Field: How Two Men Revolutionized Physics.

Faraday was largely self-taught and made important realizations without the benefit of a formal education in mathematics, while Maxwell was regarded as among the most brilliant mathematical physicists of his time. This double biography examines their differing lives and explains how their combined work paved the way for modern physics.

 

2. The Cosmic Cocktail: Three Parts Dark Matter

Katherine Freese

In The Cosmic Cocktail: Three Parts Dark Matter, physicist Katherine Freese explores the critical place dark matter occupies in our understanding of the cosmos.

It has yet to be observed directly. But, she tells us, dark matter’s day of reckoning might not be far off.

“Some new particles, unlike any from our daily experience, might be tearing through the galaxy,” she writes. “Scientists have already found hints of detection in their experiments… The nature of dark matter is one of the greatest puzzles of modern science, and it is a puzzle we are on the verge of solving.”

Freese, now the new director of the Nordic Institute for Theoretical Physics in Stockholm, admits to spending a disproportionate amount of time on the dance floor of nearby Studio 54 when she should have been focused on her doctoral studies at Columbia University. But she also tells a compelling history of the search for dark matter, from the cantankerous Fritz Zwicky’s early predictions in the 1930s to hopes for an appearance when the Large Hadron Collider fires up again in 2015.

 

3. The Large Hadron Collider: The Extraordinary Story of the Higgs Boson and Other Stuff that will Blow Your Mind

Don Lincoln

“My goal was to give readers an inside account of the hunt and discovery,” says Fermilab scientist Don Lincoln, a member of CERN’s CMS experiment, of his latest book, The Large Hadron Collider: The Extraordinary Story of the Higgs Boson and Other Stuff that will Blow Your Mind. “Almost all of the similar books have been written by non-physicists and theorists. I went to all the meetings, so I have a unique perspective.”

In the book, Lincoln describes the process of the discovery of the Higgs boson—and explains that it is not the end of the story.

Even though the widely celebrated appearance of the Higgs particle confirmed theorists’ predictions, Lincoln maintains that the relatively light mass of the Higgs raises enough questions to keep physicists awake at night.

“The measurement is quite inconsistent with the Standard Model and the quantum corrections,” he says. “This absolutely screams that there is something still to be found and this could be supersymmetry, extra dimensions, composite Higgs bosons or some other kind of new physics. In short, we know there is something big we’re missing.”

 

4. The Most Wanted Particle: The Inside Story of the Hunt for the Higgs, the Heart of the Future of Physics

Jon Butterworth

“I wanted it to give readers a sense of what it really feels like to work in a big experiment at such an amazing time and what it meant,” says University College London physicist Jon Butterworth of his book The Most Wanted Particle: The Inside Story of the Hunt for the Higgs, the Heart of the Future of Physics. “This meant occasionally the physics had to go a bit deeper than the common analogies, but also there is a lot of non-physics story which hopefully captures the real-time excitement.”

Butterworth, who works on the ATLAS experiment at CERN, uses a personalized approach to convey a sense of scene. In one chapter, he describes explaining the Higgs discovery to British TV reporter Tom Clarke while the two shoot pool.

He also uses his current hometown in England to describe his workplace at CERN, comparing the size of the Large Hadron Collider tunnel to the size of the London Underground.

The book, released in the UK in May under the title Smashing Physics: Inside the World’s Biggest Experiment, will be released in the US in January 2015.

 

5. The Perfect Wave: With Neutrinos at the Boundary of Space and Time

Heinrich Pas

Heinrich Pas, a theorist at the Technical University of Dortmund in Germany, studies neutrinos, particles that seem to defy the rules but may hold answers to the deepest questions of the universe.

In The Perfect Wave: With Neutrinos at the Boundary of Space and Time, Pas explains how powerful processes in the cosmos—from the fusion that lights the sun to the magnificent explosions of supernovae—are bound up in the workings of the mysterious particles.

“It is a story of an elementary particle that, just like the Silver Surfer in the superhero cartoons, surfs to the boundaries of knowledge, of the universe and of time itself,” Pas writes. “A story that captivates you as it sucks you into a maelstrom like an oversized wonderland. Jump on your board and hold tight.”

 

6. The Science of Interstellar

Kip Thorne

Kip S. Thorne, the Feynman Professor of Theoretical Physics Emeritus at Caltech, served as the executive producer for scientific credibility (and flexibility) on the space epic Interstellar. He explains that work in the book The Science of Interstellar.

In the film, astronaut Cooper (Matthew McConaughey) takes leaps and bounds over, under, around and through black holes and wormholes on his quest to find a refugee planet for the population of Earth, whose food supply is devastated by global blight.

Thorne writes that “[s]ome of the science is known to be true, some of it is an educated guess, and some is speculation.”

But he takes all of it seriously; Thorne and his colleagues even wrote a scientific paper based on their computer simulations of the movie’s black hole.

 

7. The Singular Universe and the Reality of Time

Roberto Mangabeira Unger, Lee Smolin

Physicist Lee Smolin of Canada’s Perimeter Institute for Theoretical Physics, author of the controversial book The Trouble With Physics, collaborated with philosopher and politician Roberto Mangabeira Unger on the new book The Singular Universe and the Reality of Time.

In it, Smolin and Unger argue against the idea of the multiverse and declare that it is time to view the cosmos as being governed by laws that are evolving rather than laws that are immutable. They contend that, “everything changes sooner or later, including change itself. The laws of nature are not exempt from this impermanence.”

 

8. Time in Powers of Ten: Natural Phenomena and their Timescales

Gerard ‘t Hooft, Stefan Vandoren

In Time in Powers of Ten: Natural Phenomena and their Timescales, Nobel Laureate Gerard ‘t Hooft and theorist Stefan Vandoren, both of Utrecht University in the Netherlands, step back and forth in time from the minutest fractions of a second to the age of the universe and beyond. Observations range from the orbits and rotations of planets and stars, down to the decay times of atoms and elementary particles and back to geological time scales.

“The smallest matter mankind has studied moves considerably faster than the quickest computing processes of the most expeditious machine; while on the other side of the timescale we see planets, stars and entire galaxies of unimaginably old age, some billions of years,” ‘t Hooft and Vandoren write. “Scientists believe they know almost exactly how old the universe is, but even its seemingly eternal lifetime does not constitute a limit for physicists’ research.”

 

9. Travelling to Infinity: The True Story Behind the Theory of Everything

Jane Hawking

In Travelling to Infinity: The True Story Behind the Theory of Everything, readers are introduced to a young, floppy-haired Stephen Hawking through the eyes of his first wife, Jane Hawking (née Wilde). Hawking published versions of this book in both 1999 and 2007, and the book was reissued this year to accompany the film adaptation, The Theory of Everything.

In the book, Jane describes an early impression of Stephen from a New Year’s party in 1963: “Clearly here was someone, like me, who tended to stumble through life and managed to see the funny side of situations. Someone who, like me, was fairly shy, yet not averse to sharing his opinions, someone who unlike me had developed a sense of his own worth and had the effrontery to convey it.”

Here is a love story in which love is not enough. Hawking leaves and marries one of the nurses who tended him. Jane marries an old family friend. The two have reconciled and are on amicable terms—a good thing when the person writing your life story is your former spouse.

 

10. What If? Serious Scientific Answers to Absurd Hypothetical Questions

Randall Munroe

Randall Munroe’s stick-figure web comic strip, xkcd, comes with a warning: “This comic occasionally contains strong language (which may be unsuitable for children), unusual humor (which may be unsuitable for adults), and advanced mathematics (which may be unsuitable for liberal-arts majors).”

There are no dumb questions, only humorous and provocative answers from Munroe, a former NASA roboticist, in his book What If? Serious Scientific Answers to Absurd Hypothetical Questions. For example:

“Q – What would happen if the Earth and all terrestrial objects stopped spinning, but the atmosphere retained its velocity?

“A – Nearly everyone would die. THEN things would get interesting…”

In “What If?” what seems like the end is often just the beginning.

Mike Perricone

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