Recommended by us: "MicroBooNE, in 3-D"

Tingjun Yang (left) and Wesley Ketchum lead the effort to develop new 3-D reconstruction 
software for the MicroBooNE experiment. Here they stand inside the MicroBooNE 
time projection chamber.Photo: Reidar Hahn

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Imagine your job is to analyze the data coming from Fermilab's MicroBooNE experiment. 

It wouldn't be an easy task. MicroBooNE has been designed specifically to follow up on the MiniBooNE experiment, which may have seen hints of a fourth type of neutrino, one that does not interact with matter in the same way as the three types we know about. The big clue to the possible existence of these particles is low-energy electrons.

But that experiment could not adequately separate the production of electrons from the production of photons, which would not indicate a new particle. MicroBooNE's detector, an 89-ton active volume liquid-argon time projection chamber, will be able to. To take advantage of this, every neutrino interaction in the chamber will have to be examined to determine if it created an electron or a photon.

And there will be a lot of interactions to study — the MicroBooNE collaboration expects to see activity in their detector once every 20 seconds, including nearly 150 neutrino interactions each day.

If all goes to plan, human operators won't have to worry about any of that. When MicroBooNE switches on next summer, it will sport one of the most sophisticated 3-D reconstruction software programs ever designed for a neutrino experiment.

According to Wesley Ketchum and Tingjun Yang, two postdocs leading the software development team at Fermilab, MicroBooNE's computers will be able to accurately reconstruct neutrino interactions and automatically filter the ones that create electrons. The key to accomplishing this lies in the design of the time projection chamber.

Continue to read on Fermilab Today 

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Recommended by us: "Fermilab special Halloween edition" :)

Fermilab Today special Halloween edition

For the Halloween occurence the popular scientific website "Fermilab Today" decided to put related links and fake news. Take a look here and have fun :)

http://www.fnal.gov/pub/today/archive/archive_2013/today13-halloween.html

Recommended by us: Neutrinos and non-standard interactions

“ Does matter matter for neutrino flavor? The NuMI (Neutrinos at the Main Injector) beam is generated here at Fermilab and points toward the Soudan Underground Laboratory in Soudan, Minn. The MINOS collaboration detects this beam of neutrinos in its journey twice: once at Fermilab right after it is generated and once at Soudan Lab after the neutrinos have traveled 450 miles through the Earth's crust. At its generation, the beam is made up of muon-flavored neutrinos (neutrinos come in three flavors: electron, muon, and tau). After traveling such a long distance, some of the neutrinos change flavor, primarily into tau neutrinos and a few into electron neutrinos. This phenomenon of flavor change is called neutrino oscillation. By counting the number (and measuring the energy) of muon neutrinos before and after travel, MINOS can measure parameters that govern neutrino oscillations.             The presence of matter in the neutrino path may also have an impact on flavor change. If it does, the flavor              count after travel would be altered. Some of these interactions are expected from the tiny number of oscillation             generated electron neutrinos, but extra interactions of muon or tau neutrinos with the Earth are non-standard and             are thus called non-standard interactions, or NSI for short. (The Earth is made up of regular matter—electrons,              protons and neutrons—and not of matter in muon or tau flavors.) By combining its neutrino and antineutrino data sets, MINOS has constrained the non-standard interaction parameter εμτ, finding that the results are consistent with εμτ=0, shown by the gray line. The angle θ and the parameter Δm2 relate to the relative masses of the neutrinos and to how quantum mechanically "mixed" the flavors are.                                                                                               (Continue to read on Fermilab Today)                  ”

Recommended by us: Organizing the masses at MINOS

Organizing the masses at MINOS

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By combining its neutrino and antineutrino data sets, 

MINOS  has  provided first constraints on the spectrum 

of neutrino masses (represented by the sign of Δm2), the 

CP-violating phase δ,and whether muon or tau neutrinos 

are more strongly mixed  with the so-called ν3 mass state 

(indicated by θ23). The relative goodness of each scenario

 is given along the vertical axis in terms of a difference of 

log-likelihoods. The parameter Δm2 and the angles θ13 

and θ23 relate to the relative masses of the neutrinos and

to how quantum mechanically "mixed" the three types are.

Over a decade ago the evidence became clear that neutrinos, which come in three varieties, can morph from one type to another as they travel, a phenomenon known as neutrino oscillation. By tallying how often this transformation happens under various conditions—different neutrino energies, different distances of travel—one can tease out a number of fundamental properties of neutrinos, for example, their relative masses. The MINOS collaboration has been doing exactly this by sending an intense beam of muon-type neutrinos from Fermilab to northern Minnesota, where a 5-kiloton detector lies in wait deep underground.

In this new result, MINOS has observed the rare case of muon-type neutrinos changing into electron-type neutrinos. This transformation is governed by a parameter known as θ13, and the MINOS data provide new constraints on θ13 using different experimental techniques than previous measurements. MINOS also collected data with an antineutrino beam, and the real excitement comes in when combining the antineutrino and neutrino data sets. Differences between the rates of this particular oscillation mode between neutrinos and antineutrinos would point to a violation of something called CP symmetry. While physicists know that CP symmetry is violated by quarks, it remains unknown whether the same is true for neutrinos. A new source of CP violation is required to explain why the universe began with more particles than antiparticles, and neutrinos could hold the key. (If the universe began with equal numbers of particles and antiparticles, they would have subsequently annihilated away, leaving nothing left over to make the stars and galaxies we have today.)

(Continue to read on Fermilab Today)

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Recommended by us: gravitons

“  Gravitons Sesame Street has a learning game that goes with the jingle "One of these things is not like the other. One of these things just doesn't belong." Can you find which one is different? If you've read anything about the kinds of physics we do at Fermilab, you've heard lots of words ending with "on" – words like proton, neutron, gluon, photon, boson, fermion and on and on and on. One of the words you might have encountered is the graviton. Let's get one thing out of the way: At the moment, gravitons are entirely theoretical constructs that delicately walk the knife-edge precipice between the domains of scientific respectability and the shady world of hand waving. The fantastic success of quantum theory to describe three forces – electromagnetism and the strong and weak nuclear forces – provides a considerable impetus to try to marry it to the fourth force of gravity. In the same way that the photon is known to be the quantum particle of the electromagnetic force and the gluon is the quantum particle of the strong force, the "graviton" is the name given to a hypothetical quantum particle of the gravitational force. However, a quantum theory of gravity has so far been elusive. Einstein's theory of general relativity has been the most successful description of gravity, but when it encounters the quantum realm, it predicts nonsense, with impossible infinities popping up throughout the calculations. Infinities like that are nature's way of saying "back to the drawing board." And though theoretical physicists have quite a way to go in coming up with such a model, it is still possible to work out some of the properties of gravitons. (Continue to read on Fermilab Today)

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