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Posts Tagged ‘“liquid argon”’

This article appeared in Fermilab Today on May 5, 2015.

Technicians John Cornele, Pat Healey and Skyler Sherwin have been crucial in preparing the LArIAT detector for beam. The liquid-argon-filled detector saw first beam on Thursday. Photo: Jen Raaf

Technicians John Cornele, Pat Healey and Skyler Sherwin have been crucial in preparing the LArIAT detector for beam. The liquid-argon-filled detector saw first beam on Thursday. Photo: Jen Raaf

Fermilab’s Test Beam Facility (FTBF) now runs a second beamline to provide particles for R&D experiments. The MCenter beamline came back to life last year after an eight-year slumber to join the facility’s other beamline, MTest.

On Thursday, April 30, accelerator operators began using the revived beamline to send particles to its first major experiment, Liquid Argon TPC in a Test Beam (LArIAT), which will help advance particle detector technologies for neutrino experiments.

The FTBF provides experiments with different types of particle beams with a range of energies. Its main purpose is the research and development of particle detectors. It is one of only two sites in the world that provides this service with high-energy hadrons, which are particles made of quarks. Since 2005, the FTBF, with its distinctive orange and blue corrugated-steel roof, has staged more than 50 experiments, conducted by scientists from more than 170 institutions in 30 countries.

“We’re very busy and fully subscribed,” said JJ Schmidt, deputy facility manager at FTBF. “The existence of two beams allows us to serve a broader class of experiments.”

Not only does the new beamline allow FTBF to serve a larger number of users, it also provides room for a greater diversity of experiments. While MTest is aimed at experiments with a turnover of about one to four weeks, MCenter caters to more long-term experiments like LArIAT that will last for months, or even years.

Beautiful tracks at first try
LArIAT is a liquid-argon time projection chamber. Charged particles traveling through the sea of liquid argon ionize the argon atoms, and an electric field causes liberated electrons to drift toward the detector readout. Different particles cause different amounts of ionization, allowing researchers to distinguish between particles such as pions, kaons and protons.

This plot shows LArIAT's first tracks: two views of a charged particle interacting inside the LArIAT detector, which is filled with liquid argon.

This plot shows LArIAT’s first tracks: two views of a charged particle interacting inside the LArIAT detector, which is filled with liquid argon.

The first spill of particles delivered to LArIAT led to immediate success. The detector recorded picture-perfect tracks of charged particles.

Like the test beam, LArIAT will act as a research and development vehicle for future projects. Because neutrinos can be studied only through the particles produced when they interact with material inside a particle detector, being able to reliably characterize these other particles is of great importance.

“This is going to be fantastic not only for LArIAT but all the neutrino experiments that will use its results,” said Jen Raaf, co-spokesperson for LArIAT.

LArIAT will run the test beam for 24 hours a day while experimenters take data. The first run will last about three months, after which the detector’s cryogenic system will undergo upgrades to prepare for longer follow-up runs.

“It’s great that we have a facility where a small experiment can take beam over a long term,” said Brian Rebel, a scientist involved in LArIAT.

About 75 people from 22 institutions from the United States, Europe and Japan work on this experiment.

“Most are young postdocs and Ph.D. students that are enthusiastically doing a great job,” said Flavio Cavanna, LArIAT co-spokesperson.

“It’s an exciting combination of many years of work by the Accelerator, Particle Physics, Neutrino and Scientific Computing divisions to have the capability to do research that is important for making this the premier neutrino laboratory in the world,” Schmidt said.

Diana Kwon

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Welcome to LAr week

I arrived this morning in Marrakech, Morocco, for ATLAS’s “Liquid Argon Week.” No, we’re not going out in search of liquid argon in the desert. I’m going to meet up with colleagues that I work with to make sure our part of ATLAS is ready go when the first collisions of the LHC take place.

The ATLAS experiment has many different pieces, and each piece measures different aspects of the collisions provided by the accelerator. The piece that I work on is called the Liquid Argon Calorimeter. A calorimeter is a device that measures energy. Ours is called the “Liquid Argon” (abbreviated to “LAr”) calorimeter because liquid argon is the substance inside the detector that lets us know that particles passed through it. As particles from the LHC collisions enter the argon, they ionize the argon and we can infer the energy of the particles from the ions they left behind. Argon is usually a gas at room temperature, but the gas would not be dense enough to help us measure the energy well. We have to cool the argon to -186 degrees Celsius (about -300 degrees F) to use it in ATLAS! If you want to learn more about how the calorimeter works, I recommend this video which explains many of the ATLAS subsystems with great illustrations. There are actually four different types of liquid argon calorimeters used in ATLAS, but they share many of the same tools and challenges, so all the people working on those detectors form the “Liquid Argon Calorimeter Group” within ATLAS.

People who work on these calorimeters get together every few months to share their progress and make plans for the future. The same thing is done for other systems of ATLAS: there is a “muon detector week” and an “inner detector week” and then there are weeks for all of ATLAS to get together. Usually these weeks are at held at CERN, but once a year, they may be held outside CERN. The outside-of-CERN weeks give one of the groups a chance to show their colleagues around their home town. It also gives people from that area a break from travelling all the way to CERN. Being away also allows/forces people to get away from their usual offices, tasks, and social circles at CERN. There are scheduled talks, and a lot of other important and useful discussions take place over coffee (or mint tea!) or lunch or dinner while people are away
from home, together.

This week, our Liquid Argon Calorimeter colleagues from Morocco have invited us all to meet in Marrakech. We’ll have four days of meetings on different topics relating to the calorimeters, and then a free day at the end of the week for exploring. There will be a big dinner one night with Moroccan food — I’m looking forward to that!

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