Bob’s most excellent particle detector adventure

June 13, 2011 | 12:02 pm

One month ago, Fermilab’s Bob Peterson embarked on a month-long journey in the Atlantic Ocean with two cosmic ray muon detectors, collecting data for science and education programs. This offers a chance to study how cosmic ray recordings differ on land and sea and at different latitudes. The data will be accessible to high school students and teachers in several countries who use similar detectors to learn about particle physics. Bob recorded the entire adventure, which concluded last week, in Quantum Diaries. He posted the following entry on May 12, just as his ship was about to pass the equator.

Enduring a branding for QuarkNet science education

4 May 2011
R/V Polarstern
Latitude: 9-47.1 N
Longitude: 19-46.2 W
off the coast of Guinea
Ship course 320 ° T
Ship velocity 10.1 knots

4 May 2011:
Two days ago, the R/V Polarstern stopped mid-ocean at latitude: 00-00.053S, longitude: 11-39.259W.

By my reckoning, that’s 318 feet south of that east-west line “painted” in the water. Guilty parties were forced into very little rubber rafts and pointed in obscure directions and told to “cross the line”. Only one actually knew which way to go. After circular paddling, which amounted to three times the distance required to cross the line, those guilty of being equator-crossing newbies were initiated as shellbacks .

And what an initiation it was.

Neptune, lord of the sea, and his court rose up out of the Atlantic for the ritual baptism of those who had violated his domain. A trial was held and renaming of the pollywogs was required. Much fun and antics was had by the entire crew as they put on a real show of cruel and dastardly deeds. I could almost hear them cackling like the pirates of days past: “Arrrghhh! Avast ye maties!”

Bathing in stinky slop ensued, ceremonial memorizing of creeds was demanded and kissing of the feet of Neptune’s wives was enjoyed. Men in drag wearing clown shoes slathered in mustard and horseradish sauce stood in for Neptune’s wives. Lovely. I was also assisted by large, burly men with tattoos into a baptismal font made from a large fish basket. Four times I went in it; I must have been extra sinful. Each dunking got nastier as more people were “baptized”.

Finally they branded our stomachs with Neptune’s trident. This was a bit scary because they covered our faces with hoods execution-style and we could hear the metal trident heating in a charcoal grill and sizzling as it pressed onto flesh. Thankfully, when it came to my turn I found out the sizzle was the trident branding a raw piece of meat that then got slapped onto my stomach.  The crew got a great laugh out of our initiation.

We earned certificates for our ceremonial passage and a feast at sunset. Neptune felt the ceremony was befitting and left without taking the ship with him. So I am now the shellback known as Cosmic-Ray Rider, and I have pictures and a certificate to prove it.

Those will have to do because I skipped one of the most permanent parts of the ceremony. While I appreciate all the suggestions of earring types from friends and family, I decided to forego that little ritual. It’s the burly men that punch the hole, and they’re none too delicate.

So, the cosmic ray muon detector gave me my shellback name, but it’s also been my source of grief. Sometimes delicate instruments refuse to cooperate. For me, the trouble has been channel four and a scintillator counter that drops off line. Of course, it’s the one on the bottom of the stack, and it chooses to act up in the middle of the night. Several times in the morning I find it asleep, and that no data was taken during the night. Suspecting a light leak, I rewrapped it twice. Nope; that’s not it. Then I discover a flakey wire into the photo multiplier tube. There must be a short inside that photo multiplier tube. To compensate, I have lowered the coincidence to 3-fold from four so that a particle signal recorded in the three working sections of the detector will count as cosmic ray remnant event. Now, I will at least get some data. A replacement wire is some 8,000 miles away at Fermilab and the parts you can find along our route are pretty wet wheeling, as they say.

After many days in the southeast trade winds, we pushed through the doldrums, an area of still air near the equator that seems to rise rather than blow, and into the northeast trade winds. Other than the stop for the equator crossing, our course and speed have been relentless: 320 ° T, 11 knots; however, the following winds and swell have now turned on the nose and have become quite lumpy. Max, the weather guesser, promises it will get worse. In several days we make a turn to the north and a planned stop at the Canary Islands to pick more scientists.

Glossary:
*Pollywog: Some no good, inexperienced mariner who has never crossed the equator.

*Shellback: The opposite of a pollywog.

*Coincidences: The cosmic ray muon detector looks for what we call coincidences, two signals, one from each photo multiplier tubes, received within a short time. These are reported to the computer; all other signals are vetoed as likely background noise from the photo multiplier tubes.

– Bob Peterson

 

 

 

 

Guest author

No Comments »

AMS-02 antimatter detector lifting off in 3, 2…

April 29, 2011 | 11:00 am

Edit: The shuttle launch has been postponed until May 16 due to heater issues. For the latest news follow @AMS_02.

In about four hours, the Endeavour space shuttle is scheduled to launch from the Kennedy Space Center on its final mission, carrying with it what will be the largest physics experiment to blast into space.

Watch the event live via a CERN webcast or follow the detector on Twitter.

The Endeavour will deliver to the International Space Station the Alpha Magnetic Spectrometer experiment. AMS-02 will bring scientists a new understanding of the makeup of the universe by collecting information from subatomic particles accelerated to energies far beyond those attainable by a man-made particle accelerator.

Astrophysicists postulate that the explosions of stars and other dramatic events in space release high-energy cosmic rays, which can travel for hundreds of millions of light years before reaching Earth. Once the rays collide with Earth’s atmosphere, they can be absorbed or break into showers of particles. Physicists are sending AMS-02 into space in order to catch cosmic rays before that happens.

AMS-02 will search for the unexpected, but scientists have a few items on their wish-lists for the detector, including primordial antimatter and dark matter particles.

Primordial antimatter is antimatter created during the big bang. Scientists think the big bang should have created equal amounts of matter and antimatter. When matter and antimatter meet, they annihilate into particles of light. But the universe as we know it is made almost entirely of matter. If AMS-02 detected antimatter particles in cosmic rays, it could mean that primordial antimatter still exists in abundance; we just haven’t found it yet.

Dark matter is matter that exerts a gravitational pull but does not absorb or emit light. The behavior of galaxies and the way we see them lead scientists to believe that almost a quarter of the universe is made up of dark matter. However, they have yet to detect dark matter particles. Some theories state that dark matter could be made up of particles called neutralinos. If these particles exist, they could collide with one another and produce excesses of charged or neutral particles the AMS-02 could detect.

AMS-02 will collect between 2,000 and 2,500 events per second and is scheduled to remain in orbit at the space station for at least a decade.

About three and a half days after today’s lift-off, the shuttle will reach the same orbital configuration as the International Space Station about 200 miles above the Earth. Once it has docked there, astronauts will remove the detector from the shuttle cargo area and attach it to the space station in an extraterrestrial hand-off using two giant robotic arms – one attached to the Endeavour and the other attached to the ISS. Less than an hour after they secure AMS and hook it up to the space station’s electrical supply, the detector will be able to start sending data back to Earth.

For more information about following the launch, see the press release. For more photos and videos, see the AMS-02 website.

Kathryn Grim

1 Comment »

The AMS detector heads for the International Space Station

April 27, 2011 | 11:50 am

The following press release was issued today by CERN.

Geneva 27 April 2011. The AMS particle detector will take off on 29 April 2011 at 21.47 CEST onboard the very last mission of the space Shuttle Endeavour. AMS, the Alpha Magnetic Spectrometer, will then be installed on the International Space Station from where it will explore the Universe for a period of over 10 years. AMS will address some of the most exciting mysteries of modern physics, looking for antimatter and dark matter in space, phenomena that have remained elusive up to now.

In laboratories like CERN, physicists observe matter and antimatter behaving in an almost identical way. Each matter particle has an equivalent antiparticle, very similar but with opposite charge. When particles of matter and antimatter meet, they annihilate. Matter and antimatter would have been created in equal amounts at the Big Bang, yet today we live in a Universe apparently made entirely of matter. Does nature have a preference for matter over antimatter? One of the main challenges of AMS will be to address this question by searching for single nuclei of antimatter that would signal the existence of large amounts of antimatter elsewhere in the Universe. To achieve this, AMS will track cosmic rays from outer space with unprecedented sensitivity.

“The cosmos is the ultimate laboratory,” said Nobel laureate and AMS Spokesperson Samuel Ting. “From its vantage point in space, AMS will explore such issues as Antimatter, Dark Matter and the origin of Cosmic Rays. However, its most exciting objective is to probe the unknown because whenever new levels of sensitivities are reached in exploring an unchartered realm, exciting and unimagined discoveries may be expected.”

In the same way that telescopes catch the light from the stars to better understand the Universe, AMS is a particle detector that will track incoming charged particles such as protons, electrons and atomic nuclei that constantly bombard our planet. By studying the flux of these cosmic rays with very high precision, AMS will have the sensitivity to identify a single antinucleus among a billion other particles.

“This is a very exciting moment for basic science,” said CERN Director General Rolf Heuer. “We expect interesting complementarities between AMS and the LHC. They look at similar questions from different angles, giving us parallel ways of addressing some of the Universe’s mysteries.”

AMS may also bring an important contribution to the search for the mysterious dark matter that would account for about 25% of the total mass-energy balance of the Universe. In particular, if dark matter is composed of supersymmetric particles, AMS could detect it indirectly by recording an anomaly in the flux of cosmic rays.

“Never in the history of science have we been so aware of our ignorance,” said AMS Deputy Spokesperson Roberto Battiston. “Today we know that we do not know anything about what makes up 95% of our Universe.”

AMS is a CERN recognized experiment and as such has benefited from CERN’s expertise in integrating large projects, from CERN’s vacuum and magnet groups and from test beam facilities for calibrating the detectors. In addition, the Payload Operation Centre (POC) of AMS will open in June 2011 at CERN, very near to the place where the AMS detector was assembled in clean room facilities. From the POC, physicists will be able to run the AMS detector as well as receive and analyse data arriving from the International Space Station.

AMS is the result of a large international collaboration with a major European participation. It is led by Nobel laureate Samuel Ting and involves about 600 researchers from CERN Member States (Denmark, Finland, France, Germany, Italy, the Netherlands, Portugal, Spain, Switzerland) as well as from China, Korea, Mexico, Taiwan, and the United-States.

Follow the launch of AMS live:

The launch of AMS can be followed live via webcast at: http://webcast.cern.ch
Questions can be asked during the webcast by sending them to @cern on twitter

The live will also be broadcasted through EBU Eurovision services.
A VNR preview will be broadcasted on 28 April 2011, 10:00 – 10:15 GMT.
More information on http://www.eurovision.net/

Videos are available at: http://bit.ly/cernamsfootage
Videos are subject to the CDS conditions of use: http://bit.ly/CDSconditionsofuse

For updates about of AMS, follow @astroparticle and @ams_02

Information about AMS can be found at www.ams02.org

Elizabeth Clements

No Comments »

Dark Energy Camera ready for shipping to Chile

April 16, 2011 | 10:41 am

This story first appeared in DOE Pulse on April 4.

Building and installing one of the world’s largest digital cameras to solve the mystery of dark energy requires the collaboration of scientists and industry from across the globe. The Dark Energy Survey’s combination of survey area and depth will far surpass the scope of previous projects and provide researchers for the first time with four search techniques in one powerful instrument. More than 120 scientists are collaborating to determine the true nature of dark energy, the mysterious force that accelerates the expansion of the universe. Taking images of galaxies from the time the universe was only a few billion years old, the DES will trace the history of the expanding universe roughly three-quarters of the way back to the time of the Big Bang.

But first researchers needed to build the 570-megapixel camera at DOE’s Fermi National Accelerator Laboratory and make sure it works. Nearly all of the camera’s parts made their way to Fermilab for assembly and testing during the last 12 months. The components were assembled and operated on a full-size replica of the front end of the 4-meter Blanco telescope in Chile, built by Fermilab and Argonne National Laboratory.  Testing finished successfully in February. During the next few months, physicists will be putting the finishing touches on pieces of the camera and shipping them to the Cerro Tololo Inter-American Observatory in Chile where they will receive another round of tests before installation.

The high-tech supply chain tapped the expertise at four DOE Office of Science national laboratories and more than two dozen institutions and universities in the United States and abroad.  More than 120 companies in the United States contributed know-how and parts. Fermilab took the lead in the assembly and testing of the camera and building a cryogenics system several times larger than those used in previous ground-based sky surveys, while Berkeley and Argonne national laboratories played key roles in the camera development.

Berkeley Lab developed the Charge Coupled Devices used in the camera and did some of the processing of the silicon for the CCDs before sending the pieces to Fermilab for packaging of CCD chips. The unique design of these CCDs will give the camera unprecedented sensitivity for red and near-infrared wavelengths, allowing it to record more light for a given exposure time. The camera contains 62 CCDs for observing with 8 million pixels each, plus 12 CCDs with 4 million pixels each for guiding and focusing.

Argonne National Laboratory helped construct the calibration camera to conduct a mini-sky survey last year from a telescope adjacent to the Blanco telescope. This scaled-down version of the dark energy camera allowed for testing of the experiment hardware, software and observing strategies as well as created a baseline of celestial objects for Dark Energy Survey. Argonne also constructed several smaller components for the full-size camera and some large mechanical systems, including the heavy apparatus that installs and removes a 1-ton mirror from the front of the camera.

SLAC National Accelerator Laboratory took the lead in constructing a separate, small telescope with an infrared camera that will sit on a mountain near the Blanco telescope in a separate enclosure. This telescope will monitor cloud coverage so that the Dark Energy Camera can adapt its survey modes to various atmospheric conditions.

The DES collaboration expects to take its first astronomical images with the installed Dark Energy Camera before the end of 2011.

Tona Kunz

5 Comments »

Particle physicist lends skills to planet hunt

February 4, 2011 | 2:11 pm

Yet, Jason Steffen, an astrophysicist at Fermilab, is a long-time member of NASA’s Kepler Mission and its only practicing  particle physicist. He helped make possible the mission’s discoveries announced Wednesday of a six-planet solar system 2,000 light years away, tits first Earth-sized planet candidate, and the first such candidate that potentially could support human life.

It’s one small step for Steffen and his Kepler collaborators and one giant step for dreamers everywhere.

“In one generation we have gone from extraterrestrial planets being a mainstay of science fiction, to the present, where Kepler has helped turn science fiction into today’s reality,” says NASA administrator Charles Bolden upon announcing the data release.

The Kepler spacecraft-mounted telescope, 11 million miles from Earth,  scans the sky to find, for the first time, distant life-sustaining planets the size of Earth.  Telescopes can’t directly spot planets smaller than Jupiter, but Kepler uses starlight to indirectly see smaller planets. Planets that could potentially sustain life fall into a Goldilocks-like “habitable zone,” orbiting the perfect distance from a star like our sun so as to not be too hot or too cold. Often these planets’ orbits cross close in front of a star, or “transit,” making them visible through the blinking out of the stars’ light.  By measuring the brightness change of a star as a planet passes in front of it, as well as  the time between these transits, scientists can tell the planet’s size, orbit, and estimated temperature.

But the closeness to the star that allows Kepler to “see” the planet also often makes it too hot for life. The more distant planets outside Kepler’s view hold a greater chance of being just right to sustain life. Kepler has difficulty spotting these planets because of orbit cycles that are longer than the time frame of the released data or because they do not transit stars.

That’s where Steffen comes in.

“We are sensitive to planets that Kepler can’t see directly,” says Steffen of the analysis team he leads. “That is where it gets interesting.”

He helped pioneer a search method that can detect distant planets more than 600 times smaller than Jupiter and out of range of Kepler‘s telescope. He uses computerized mathematical procedures, called algorithms, including many that are commonplace to particle physics, to probe deeper into space in the area around a planet Kepler sees to find planets in that often cooler, more habitable zone.

This is done by studying the amount of time it takes a planet to complete its orbit past a star. Deviations from a constant orbit time  indicate the presence of some additional unseen planet whose gravitational pull is changing the orbit speed of the observed planet. This technique is used to confirm that distant images seen by the Kepler telescope are planets and not pairs eclipsing binary stars blurred by the telescope to resemble an object of planet size.

Steffen expects to look at hundreds of planetary systems during the mission’s 3 ½ years. By looking at patterns in the times it takes planets to transit, scientists could fill in some blanks about how planetary systems form with relation to their distance from a sun.

The discoveries announced Wednesday are part of several hundred planet candidates identified in new Kepler mission science data release. The findings increase the number of planet candidates identified by Kepler to date to 1,235. Of these, 68 are approximately Earth-size; 288 are super-Earth-size; 662 are Neptune-size; 165 are the size of Jupiter; and 19 are larger than Jupiter. Of the 54 new planet candidates found in the habitable zone, five are near Earth-sized. The remaining 49 habitable-zone candidates range from super-Earth size — up to twice the size of Earth — to larger than Jupiter.

The findings are based on the results of observations conducted from May 12 to Sept. 17, 2009, of more than 156,000 stars in Kepler’s field of view, which covers approximately 1/400th of the sky.

Based on this large data sample “….it turns out that close to 20 percent of all stars are orbited by
planets, meaning that a significant fraction of the stars in the sky are orbited by alien worlds,” says Tim Brown, Kepler co-investigator and physics professor at the University of California Santa Barbara, in a press release.

Just as Kepler collaborators look  for a planet that is just right for habitation, the group also needed just the right skill set to expand its search reach. Steffen happened to be one of the only people in the world versed in that area of research because of his graduate degree work in transit timing variations.

NASA to note and asked him to join the Kepler mission as a participating scientist, collaborators drawn from outside the normal NASA research field to to enable the team to more effectively execute the mission’s science program.

Steffen and his thesis advisor Eric Agol, associate professor of astronomy at the University of Washington, fine-tuned this method of tracking fluctuations in the orbits of planets, making it unexpectedly useful for short-time mission such as Kepler’s planet hunting.

Scientists had tracked orbit fluctuations before but always on the time scale of comparing  many thousands of orbit cycles during the course of many decades. Using smaller data sets taken during shorter periods of time seemed pointless because they generated such small effects–until Steffen and Agol came along.

By introducing a  new tracking method, they reduced the time needed to identify these hard-to-find planets to a year with only a dozen or two orbit cycles.  Matt Holman, an astronomer with the Harvard-Smithsonian Center for Astrophysics, had also been focusing on the same problem. The two joined together to adapt their tracking methods, along with help from colleagues across the country, for the Kepler exoplanet hunt.

This work with exoplanets doesn’t have direct applications to high-energy physics or Steffen’s other work at Fermilab on chameleons, axion particles, and holographic noise. However, particle physics uses many of the same mathematical algorithms in experiments and there is no telling whether Steffen’s technique could become useful in that field in the future.

“It’s fair to say I can cannibalize the components of the algorithm for future projects,” Steffen says.

–Tona Kunz

For more information:

Kepler mission website

Kepler discovers new planetary system press release

Kepler finds Earth-size planet in habitable zone press release

Kepler public data website

Tona Kunz

1 Comment »

Astronomical computing

October 18, 2010 | 10:00 am

This story first appeared in iSGTW on October 13, 2010. It discusses the computing needs of the Large Synoptic Survey Telescope, which astrophysicists hope to use in their search for dark matter and dark energy, among other things.

The Large Synoptic Survey Telescope to be constructed in Chile will incorporate the world’s largest digital camera, capable of recording highly detailed data more quickly than any other telescope of comparable resolution.

For the scientists working on the project, that all amounts to an exciting opportunity to learn more about moving objects (including monitoring asteroids near the Earth), transients such as the brief conflagrations of supernovae, dark energy, and the structure of the galaxy.

For computing specialists, it means more data. A lot more data.

The LSST will take between 1000 and 2000 panoramic 3.2 gigapixel images per night, covering its hemisphere of the sky twice weekly. Along with daytime calibration images, this will amount to 20 terabytes of data stored every 24 hours.

It’s a long journey from the summit of Cerro Pachon in Chile, the future site of the telescope, to the hundreds of research papers that the telescope’s data will inspire over its mandated ten-year lifespan. The journey begins with around-the-clock shifts to monitor the instruments and data for quality control. Scientists will be able to do shifts from either the summit site’s control room, or from the remote control room at the base site in La Serena, Chile; data is transmitted between the two sites via dedicated 10 gigabits per second fiber optic lines.

At the base site, approximately 3000 computing nodes with 16 cores each wait to make a rapid analysis of the data as it comes in.

“We have 60 seconds, basically, to do an initial reduction of that data and find any sort of astronomical transient events,” explained Jeff Kantor, project manager of data management for LSST. “And of course we have to distinguish those that are true transients from asteroids and other moving objects.”

As those transient objects are identified, subscribing scientists will receive alerts. This gives them a chance to orient other telescopes on the same patch of sky in order to gather additional data.

Once per day, the raw data and metadata will be transmitted nearly 8000 kilometers to the Archive Center at the National Center for Supercomputing Applications at the University of Illinois at Urbana-Champaign, where it will be re-processed and merged into the archives.

The Archive Center will require 100 teraflops of processing power and the capacity for 15 petabytes of storage — at first.

“Once a year we have to take that data and re-process all of the accumulated images since the survey started, in one year. And so our processing requirements go up each year,” Kantor said. “Ultimately, that will require in excess of 250 teraflops of computing power, which is a fairly big chunk of computing capability.”

Scientists and citizens alike will be able to access the data in a variety of ways. Members of the LSST team are researching technologies that will assist them in deploying a science gateway where researchers can access the data and perform basic analyses. Kantor expects, however, that other organizations will want to establish their own portals, which LSST plans to support with open interfaces that comply with Virtual Observatory standards. Likewise, the software, which is all open source, runs on the TeraGrid.

“We are doing prototype implementations of the system right now, during our ‘R&D’ phase, and each year we do a fairly substantial software project and process terabytes of pre-cursor and simulated image data,” Kantor said. “We are using the TeraGrid for that purpose.”

More recently, the LSST team has begun to explore how they could use the resources offered by Open Science Grid.

“Many of our applications are what you’d call embarrassingly parallel,” Kantor explained. “My understanding is that it [OSG] has lots of locations that are well-suited to the embarrassingly parallel type of application.”

It’s still early days for the LSST, which is scheduled to complete its design and development phase in a few years and construction and commissioning within a decade. Over twenty years of preparation will culminate in a ten-year survey. Creating the telescope and infrastructure has certainly posed a set of pretty technical problems.

Said Kantor, “Why do we think we can do it? Because we’ve got pretty much world experts in every key area on the team, from petascale database to astronomical data processing algorithms.”

Miriam Boon

1 Comment »