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Posts Tagged ‘neutrinos’

Massive thoughts

Thursday, April 24th, 2014

This article appeared in symmetry on April 24, 2014.

The Higgs boson and the neutrino fascinate the general public and particle physicists alike. Why is that?

The Higgs boson and the neutrino fascinate the general public and particle physicists alike. Why is that?

If there are two particles that everyone has read about in the news lately, it’s the Higgs boson and the neutrino. Why do we continue to be fascinated by these two particles?

As just about everyone now knows, the Higgs boson is integrally connected to the field that gives particles their mass. But the excitement of this discovery isn’t over; now we need to figure out how this actually works and whether it explains everything about how particles get their mass. With time, this knowledge is likely to affect daily life.

One way it could possibly bridge the gap between fundamental research and the commercial market, I believe, is in batteries. The ultimate battery in nature is mass. The expression E=mc2 is a statement of that fact. During the early moments of the universe, all particles were massless and traveling at the speed of light. Once the Higgs mechanism turned on, particles suddenly began interacting with the field and, in this process, converted their energy into what we now refer to as mass. In a recent address to the Canadian Nuclear Society, I suggested that if engineers of the future could learn how to manipulate the Higgs field (to “turn it on and off”), then we would have developed the ultimate energy source and the best battery nature has created. This idea definitely belongs in the science-fiction category, but remember that progress in science is driven by thinking “outside the box!”

This sort of thinking comes from looking at the Higgs from another angle. According to the Standard Model, many particles come in left-handed and right-handed versions (in the former, the particle’s direction of spin matches its direction of motion, while in the latter, they are opposite).

Keeping this fact in mind, let’s look at the mass of the familiar electron as an example. When we say that the mass of the electron is created by interactions with the Higgs field, we can think of this as the Higgs field rapidly changing a left-handed electron into a right-handed electron, and vice versa. This switching back and forth is energy and, through E=mc2, energy is mass. A heavier particle like the top quark would experience this flipping at a much higher frequency than a lighter particle like the electron. As we learn more about how this process works, I encourage physicists to also seek applications of that knowledge.

And what about neutrinos? Do they get their mass from the Higgs field or in a completely different way? Once thought to be massless, neutrinos are now known to have a tiny mass. If the Higgs mechanism is responsible for that mass, there must exist both a left-handed and a right-handed neutrino. A good number of physicists think that both are out there, but we do not yet know. That knowledge may help us understand why the neutrino mass is tiny, as well as why there is more matter than antimatter in the universe—one of the most important questions facing our field of particle physics.

But since the neutrino is a neutral particle, the story gets more interesting. It may instead be possible that there is another type of mass. Referred to as a Majorana mass, it is not a mass described by the flipping of left- and right-handed neutrinos back and forth, but it is “intrinsic,” not derived from any kind of “motional energy.” I expect that the efforts by our field of particle physics, in the collective sense, will pursue the questions associated with both the Higgs boson and the neutrino with enthusiasm, and that the results will lead to advancements we can’t even imagine today.

Nigel Lockyer, Fermilab director

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Fermilab released this press release on Feb. 11, 2014.

Workers at the NOvA hall in northern Minnesota assemble the final block of the far detector in early February 2014, with the nearly completed detector in the background. Each block of the detector measures about 50 feet by 50 feet by 6 feet and is made up of 384 plastic PVC modules, assembled flat on a massive pivoting machine. Photo courtesy of NOvA collaboration

Workers at the NOvA hall in northern Minnesota assemble the final block of the far detector in early February 2014, with the nearly completed detector in the background. Each block of the detector measures about 50 feet by 50 feet by 6 feet and is made up of 384 plastic PVC modules, assembled flat on a massive pivoting machine. Photo courtesy of NOvA collaboration

Scientists on the world’s longest-distance neutrino experiment announced today that they have seen their first neutrinos.

The NOvA experiment consists of two huge particle detectors placed 500 miles apart, and its job is to explore the properties of an intense beam of ghostly particles called neutrinos. Neutrinos are abundant in nature, but they very rarely interact with other matter. Studying them could yield crucial information about the early moments of the universe.

“NOvA represents a new generation of neutrino experiments,” said Fermilab Director Nigel Lockyer. “We are proud to reach this important milestone on our way to learning more about these fundamental particles.”

Scientists generate a beam of the particles for the NOvA experiment using one of the world’s largest accelerators, located at the Department of Energy’s Fermi National Accelerator Laboratory near Chicago. They aim this beam in the direction of the two particle detectors, one near the source at Fermilab and the other in Ash River, Minn., near the Canadian border. The detector in Ash River is operated by the University of Minnesota under a cooperative agreement with the Department of Energy’s Office of Science.

Billions of those particles are sent through the earth every two seconds, aimed at the massive detectors. Once the experiment is fully operational, scientists will catch a precious few each day.

Neutrinos are curious particles. They come in three types, called flavors, and change between them as they travel. The two detectors of the NOvA experiment are placed so far apart to give the neutrinos the time to oscillate from one flavor to another while traveling at nearly the speed of light. Even though only a fraction of the experiment’s larger detector, called the far detector, is fully built, filled with scintillator and wired with electronics at this point, the experiment has already used it to record signals from its first neutrinos.

“That the first neutrinos have been detected even before the NOvA far detector installation is complete is a real tribute to everyone involved. That includes the staff at Fermilab, Ash River Lab and the University of Minnesota module facility, the NOvA scientists, and all of the professionals and students building this detector,” said University of Minnesota physicist Marvin Marshak, Ash River Laboratory director. “This early result suggests that the NOvA collaboration will make important contributions to our knowledge of these particles in the not so distant future.”

Once completed, NOvA’s near and far detectors will weigh 300 and 14,000 tons, respectively. Crews will put into place the last module of the far detector early this spring and will finish outfitting both detectors with electronics in the summer.

“The first neutrinos mean we’re on our way,” said Harvard physicist Gary Feldman, who has been a co-leader of the experiment from the beginning. “We started meeting more than 10 years ago to discuss how to design this experiment, so we are eager to get under way.”

The NOvA collaboration is made up of 208 scientists from 38 institutions in the United States, Brazil, the Czech Republic, Greece, India, Russia and the United Kingdom. The experiment receives funding from the U.S. Department of Energy, the National Science Foundation and other funding agencies.

The NOvA experiment is scheduled to run for six years. Because neutrinos interact with matter so rarely, scientists expect to catch just about 5,000 neutrinos or antineutrinos during that time. Scientists can study the timing, direction and energy of the particles that interact in their detectors to determine whether they came from Fermilab or elsewhere.

Fermilab creates a beam of neutrinos by smashing protons into a graphite target, which releases a variety of particles. Scientists use magnets to steer the charged particles that emerge from the energy of the collision into a beam. Some of those particles decay into neutrinos, and the scientists filter the non-neutrinos from the beam.

Fermilab started sending a beam of neutrinos through the detectors in September, after 16 months of work by about 300 people to upgrade the lab’s accelerator complex.

“It is great to see the first neutrinos from the upgraded complex,” said Fermilab physicist Paul Derwent, who led the accelerator upgrade project. “It is the culmination of a lot of hard work to get the program up and running again.”

Different types of neutrinos have different masses, but scientists do not know how these masses compare to one another. A goal of the NOvA experiment is to determine the order of the neutrino masses, known as the mass hierarchy, which will help scientists narrow their list of possible theories about how neutrinos work.

“Seeing neutrinos in the first modules of the detector in Minnesota is a major milestone,” said Fermilab physicist Rick Tesarek, deputy project leader for NOvA. “Now we can start doing physics.”

Note: NOvA stands for NuMI Off-Axis Electron Neutrino Appearance. NuMI is itself an acronym, standing for Neutrinos from the Main Injector, Fermilab’s flagship accelerator.

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This article appeared in symmetry on Nov. 6, 2013.

Scientists planning the next decade in US particle physics consider what we can learn from fundamental particles called neutrinos.

Scientists planning the next decade in US particle physics consider what we can learn from fundamental particles called neutrinos.

We live in a galaxy permeated with tiny particles called neutrinos. Trillions of them stream through each of us each second. They are everywhere, but much remains a mystery about these particles, which could be key to understanding our universe.

During the first weekend of November, a couple of hundred scientists gathered at Fermilab to discuss ways to unravel the mystery of neutrinos.

The meeting was part of the process of planning the next decade of particle physics research for the United States. A group of 25 scientists on the Particle Physics Project Prioritization Panel, or P5, is studying an abundance of research opportunities in particle physics. In spring they will make recommendations about which of these opportunities should take priority in the United States.

In their first town-hall meeting, the group dedicated a full day to discussing neutrino research.

“Neutrinos have already revealed many properties of the universe, some of them unexpected,” says Antonio Masiero, the vice president of Italy’s National Institute of Nuclear Physics, who provided an international perspective at the meeting. “They still keep secrets which could reveal aspects which are new and answer questions which are still open.”

Neutrinos might help scientists understand what caused the imbalance between matter and antimatter that allowed our universe to form. They could give insight into why particles seem naturally to be organized into three generations. They could help reveal undiscovered principles of nature.

“The neutrino is still a mysterious particle,” says Fermilab physicist Vaia Papadimitriou, pictured above giving a presentation at the meeting. “When I was a graduate student, we didn’t even know neutrinos had masses.”

The next generations of neutrino experiments could reveal other surprises. For example, says Northwestern physicist Andre de Gouvea, neutrinos could turn out to be identical to antineutrinos. They could give scientists clues to the existence of undiscovered types of neutrinos, such as massive ones theorists think might have had a great influence early in the formation of the universe. Neutrinos could turn out to be the only fundamental particles that gain their mass from a source other than the just-discovered Higgs field.

Scientists have proposed a number of experiments to learn more about the properties and behaviors of neutrinos. Those answers could lead to even deeper insights.

P5 will hold at least two more town-hall meetings to discuss additional opportunities in particle physics—including dark matter and dark energy, the Higgs boson, new hidden dimensions of space and time, and the imbalance between matter and antimatter.

Kathryn Jepsen

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Le LSM(1) est un laboratoire insolite par sa situation géographique, situé à 1700 mètres sous la roche pour une meilleure observation de l’univers. Ce n’est pas sa seule particularité …

Entre la Savoie et l’Italie, dans l’atmosphère étouffante et assourdissante du tunnel du Fréjus, rien n’indique la présence du laboratoire au kilomètre 6,5. Puis, en pénétrant dans l’antre, et à la vue de cette grande caverne bardée d’instruments scientifiques dans laquelle s’affairent des chercheurs aux accents russe, grec ou chinois, c’est une excitante sensation d’être au beau milieu d’un film de James Bond qui vous saisit. A l’extérieur, dans la vallée, comme un écho à cette impression, les rumeurs vont bon train et parlent même d’expériences secrètes ! Pourtant, il n’en est rien, car l’intérêt à s’installer sous la montagne est purement scientifique. En effet, le but n’est pas de se soustraire aux regards indiscrets, mais de s’abriter du flux des rayons cosmiques qui bombardent la surface de la Terre en permanence. L’objectif est de mener des recherches sur la matière noire ou le neutrino et procéder à des mesures d’ultra faible radioactivité grâce à un niveau de bruit de fond très bas. Une quête au moins aussi palpitante qu’un scénario de James Bond !

C’est ainsi que depuis 30 ans, le laboratoire aiguise la curiosité des habitants de Modane et des vacanciers… Un lieu propice à l’échange avec les chercheurs s’est donc révélé nécessaire et a été créé en 2009 dans le bâtiment Carré Sciences situé à Modane. Près de 3000 personnes découvrent chaque année “les petits secrets de l’univers” et environ 300 chanceux visitent le laboratoire lui-même.

Tubes de Geissler-Plücker, découverte de l ionisation – photo : lsm

A l’entrée de l’exposition se trouve un cosmophone qui révèle en direct le passage des rayons cosmiques et les transforme en une mélodie de l’univers. Conçu par le Centre de Physique des Particules de Marseille (CPPM), cet instrument ludique aide à comprendre pourquoi le laboratoire cherche à se mettre à l’abri des rayons cosmiques.

Suivent ensuite des vidéos, l’exposition d’objets remarquables, des panneaux et des jeux ou encore le petit train de la radioactivité naturelle. Une chambre à brouillard, instrument fascinant, donne une touche artistique et permet de voir concrètement la trace laissée par le passage d’une particule de radioactivité venant de l’air, de la Terre, du cosmos… ou bien même de notre propre corps !

De quoi aiguiser la matière grise en attendant de percer les secrets de la matière noire…

Avec l’essor du tourisme scientifique, la qualité de cette exposition permanente et l’intérêt du laboratoire sont désormais reconnus et mis en avant par les professionnels du tourisme. L’exposition du LSM et le laboratoire lui-même sont cités dans le Guide du Routard(2), le Guide Vert Michelin(3) ou encore le Petit Futé(4). Un coup de pouce qui nous aide à partager la science avec le public. Pas mal non ?

 

 

(1) LSM : laboratoire souterrain de Modane – UMR6417 du CNRS/IN2P3 et du CEA/IRFU
(2) Guide du Routard Savoie Mont-Blanc, page 121
(3) Guide Vert Michelin Alpes du Nord – Savoie Dauphiné, page 422
(4) Petit Futé France souterraine, page 14 – Petit Futé Savoie, page 322 – Petit Futé Alpes

- Article envoyé par le Laboratoire souterrain de Modane -

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After gathering a huge amount of data the physicists at the Ice Cube experiment in Antarctica have come to an inescapable and startling conclusion. There is a massive body orbiting the Earth, and the scientists can see its “shadow” in their data. They can even trace its path across the sky.

This body is called “Luno” by some scientists and it seems to be cross the sky once every 29.5 days. The mass of Luno is estimated to be quite staggering- about 1% of the mass of the Earth! Despite its large size there seems to be little danger posed by this body, It seems to be orbiting happily, showing no sign deviating from its course. Taking a look at the data once the movement of Luno is taken into account gives a striking pattern, confirming that its orbit is indeed stable over long periods of time:

The position of neutrinos in the sky respect to Luno (Ice Cube)

The position of neutrinos in the sky respect to Luno (Ice Cube) (Link to pdf)

The Ice Cube experiment is a neutrino observatory that searches for high energy neutrinos from outer space. These are thought to be given off by gamma ray bursts, neutron stars and alien TV broadcasts. (Some controversial theories also state that we can expect high energy neutrinos from malfunctioning microwave ovens and vacuum cleaners. But it would have to be some extreme form of malfunction.) As the neutrinos cosmic rays hit Luno they interact and the associated neutrinos don’t make it to Ice Cube. This is how Ice Cube see the “shadow” of Luno:

Schematic of the shadow of Luno (Ice Cube)

Schematic of the shadow of Luno (Ice Cube) (Link to pdf)

Other observations of Luno

This is not the first time that a particle physics experiment has speculated about a massive extra terrestrial body. The experiments at LEP postulated the existence of a massive body outside the Earth that changed their centre of mass energies. The assumptions went as far as to say that Luno was responsible for huge tidal forces that changed the shape of the Earth subtly around LEP. Then again, the LEP experiments were also sensitive to the TGV train timetables and meetings of the CERN Yoga Club.

Scientists at NASA have been studying Luno and they have come to some interesting conclusions. The most striking prediction is that Luno should be visible to the naked eye. Luno should reflect electromagnetic radiation from the sun, making it particularly visible at night. It is also thought that Luno is largely responsible for the tides we see in the seas and oceans across the world, a phenomenon which had been a mystery for centuries. Luno could even block the line of sight between the sun and the Earth, causing nightfall for a brief period of time. This could cause panic for people from scientifically illiterate cultures, nocturnal animals and biochemists. After much study there have been a number of artist’s impressions to help with identification of Luno:

Artist's impression of Luno to aid identification (NASA)

Artist's impression of Luno to aid identification (NASA)

Ancient prophecy

Although Ice Cube has only discovered Luno recently, there are several examples of prophecy of Luno in various forms. Several ancient civilizations drew pictograms that represented Luno in some way with some examples, such as the Tarot deck, surviving to the present day. Some cultures even had a Luno deity, such as Khonsu of the ancient Egyptians. His pictogram includes a large figure, which carries Luno. Given the size of Luno, we should be able to see the large figure as well, but all searches have been fruitless. Some people think that this figure may be even harder to find than SUSY, or even extra dimensions (outside of the Terry Pratchett universe.)

Khonsu (discovered portions shown in gray) (Wikipedia)

Khonsu (discovered portions shown in gray) (Wikipedia)

Whatever Luno is, it should be heralded as one of the greatest discoveries of 2012, and I wouldn’t be surprised if it won the Nobel Prize!

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A Grumpy Note on Statistics

Tuesday, March 13th, 2012

Last week’s press release Fermilab about the latest Higgs search results, describing the statistical significance of the excess events, said:

Physicists claim evidence of a new particle only if the probability that the data could be due to a statistical fluctuation is less than 1 in 740, or three sigmas. A discovery is claimed only if that probability is less than 1 in 3.5 million, or five sigmas.

This actually contains a rather common error — not in how we present scientific results, but in how we explain them to the public. Here’s the issue:

Wrong: “the probability that the data could be due to a statistical fluctuation”
Right: “the probability that, were there no Higgs at all, a statistical fluctuation that could explain our data would occur”

Obviously the first sentence fragment is easier to read — sorry![1] — but, really, what’s the difference? Well, if the only goal is to give a qualitative idea of the statistical power of the measurement, it likely doesn’t matter at all. But technically it’s not the same, and in unusual cases things could be quite different. My edited (“right”) sentence fragment is only a statement about what could happen in a particular model of reality (in this case, the Standard Model without the Higgs boson). The mistaken fragment implies that we know the likelihood of different possible models actually being true, based on our measurement. But there’s no way to make such a statement based on only one measurement; we’d need to include some of our prior knowledge of which models are likely to be right.[2]

Why is that? Well, consider the difference between two measurements, one of which observed the top quark with 5 sigma significance and the other of which found that neutrinos go faster than light with 5 sigma significance. If “5 sigma significance” really meant “the probability that the data could be due to a statistical fluctuation,” then we would logically find both analyses equally believable if they were done equally carefully. But that’s not how those two measurements were received, because the real interpretation of “5 sigma” is as the likelihood that we would get a measurement like this if the conclusion were false. We were expecting the top quark, so it’s a lot more believable that the excess is associated with the top quark than with an incredibly unlikely fluctuation. But we have many reasons to believe neutrinos can’t go faster than light, so we would sooner believe that an incredibly unlikely fluctuation had happened than that the measurement was correct.[3]

Isn’t it bad that we’d let our prior beliefs bias whether we think measurements are right or not? No, not as long as we don’t let them bias the results we present. It’s perfectly fair to say, as OPERA did, that they were compelled to publish their results but thought they were likely wrong. Ultimately, the scientific community does reach conclusions about which “reality” is more correct on a particular question — but one measurement usually can’t do it alone.

———————————

[1] For what it’s worth, I actually spent a while thinking and chatting about how to make the second sentence fragment simpler, while preserving the essential difference between the two. In this quest for simplicity, I’ve left off any mention of gaussian distributions, the fact that we really give the chance of a statistical fluctuation as large or larger than our excess, the phrase “null hypothesis,” and doubtless other things as well. I can only hope I’ve hit that sweet spot where experts think I’ve oversimplified to the point of incorrectness, while non-expert readers still think it’s completely unreadable. ;)

[2] The consensus among experimental particle physicists is that it’s not wise to include prior knowledge explicitly in the statistical conclusions of our papers. Not everyone agrees; the debate is between Frequentist and Bayesian statistics, and a detailed discussion is beyond the scope of both this blog entry and my own knowledge. A wider discussion of the issues in this entry, from a Bayesian perspective, can be found in this preprint by G. D’Agostini. I certainly don’t agree with all of the preprint, but I do owe it a certain amount of thanks for help in clarifying my thinking.

[3] A systematic mistake in the result, or in the calculation of uncertainties, would be an even likelier suspect.

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This week the OPERA experiment released a statement about their famous “faster than light” neutrino measurement. In September scientists announced that they had measured the speed of neutrinos traveling from CERN to Gran Sasso and they found that they arrived slightly sooner than they should do according to special relativity. There was a plethora of scientific papers, all kinds of rumors and speculation, and most physicists simply refused to believe that anything had traveled faster than light. After months of diligent study, OPERA announced that they may have tracked down two sources of experimental error, and they are doing their best to investigate the situation.

But until we get the results of OPERA’s proposed studies we can’t say for sure that their measurement is right or wrong. Suppose that they reduce the lead time of the neutrinos from 60ns to 40ns. That would still be a problem for special relativity! So let’s investigate how we can get faster than light neutrinos in special relativity, before we no longer have the luxury of an exciting result to play with.

The OPERA detector (OPERA Collaboration)

The OPERA detector (OPERA Collaboration)

Special relativity was developed over a hundred years ago to describe how electromagnetic objects act. The electromagnetic interaction is transferred with electromagnetic waves and these waves were known to travel extremely quickly, and they seemed to travel at the same speed with respect to all objects, no matter how those objects were moving. What Einstein did was to say that the constancy of the speed of light was a fundamental law of nature. Taking this to its logical conclusion meant that the fastest speed possible was the speed of light. We can call the fastest possible speed \(s\) and the speed of light \(c\). Einstein then says \(c=s\). And that’s how things stood for over a century. But since 1905 we’ve discovered a whole range of new particles that could cast doubt on this conclusion.

When we introduce quantum mechanics to our model of the universe we have to take interference of different states into account. This means that if more than one interaction can explain a phenomenon then we need to sum the probabilities for all these interactions, and this means we can expect some strange effects. A famous example of this is the neutral kaon system. There two lightest neutral kaons are called \(K^0\) and \(\bar{K}^0\) and the quark contents of these mesons are \(d\bar{s}\) and \(s\bar{d}\) respectively. Now from the “outside” these mesons look the same as each other. They’ve got the same mass, they decay to the same particles and they’re made in equal numbers in high energy processes. Since they look identical they interfere with each other, and this gives us clues about why we have more matter than antimatter in the universe.

Since we see interference all over the place in the Standard Model it makes sense to ask if we see interference with a photon. It turns out that that we do! The shape of the Z mass peak is slightly asymmetric because of interference between virtual Z bosons and virtual photons. There are plenty of other particles that the photon can interfere with, including the \(J/\psi\) meson, and the \(\rho\) meson. In fact, any neutral vector meson with no net flavor will do. Einstein didn’t know about any of these particles, and even if he did he never really accepted the conclusions of quantum mechanics, so it’s no surprise that his theory would require that the speed of light is the fastest speed (that is, \(c=s\).) But if the photon interferes with other particles then it’s possible that the speed of light is slightly lower than the fastest possible speed (\(c<s\)). Admittedly, the difference in speed would have to be very small!

In terms of quantum mechanics we would have something like this:
\[
|light>_{Einstein} = |\gamma>
\]
\[
|light>_{reality} = a_\gamma |\gamma> + a_{J/\psi} |J/\psi> + a_Z |Z> + \ldots
\]

As you can see there are a lot of terms in this second equation! The contributions would be tiny because of the large difference in mass between the massive particles and the photon. Even so, it could be enough to make sure that the speed of light is ever so slightly slower than the fastest possible speed.

At this point we need to make a few remarks about what this small change in speed would mean for experiments. It would not change our measurements of the speed of light, since the speed of light is still extremely fast and no experiment has ever showed a deviation from this extremely fast speed. Unless somebody comes up with an ingenious experiment to show that the difference between the speed of light and the fastest possible speed is non-zero we would probably never notice any variation in the speed of light. It’s a bit unfortunate that since 1983 it’s been technically impossible to measure the speed of light, since it is used in the definition of our unit of length.

Now we know that photons can interfere with other particles it makes sense to ask the same question about neutrinos. Do they interfere with anything? Yes, they can interfere, so of course they do! They mix with neutrinos of other flavors, but beyond that there are not many options. They can interfere with a W boson and a lepton, but there is a huge penalty to pay in the mass difference. The wavefunction looks something like this:
\[
|\nu_e>(t) = a(t)_{\nu_e}|\nu_e> + a(t)_{\nu_{\mu}}|\nu_\mu> + a(t)_{\nu_{\tau}}|\nu_\tau> + a(t)_{We}|We>
\]
(I’ve had to add a time dependence due to neutrino mixing, but it’s essentially no more complicated than what we had for the photon.)

That means that the photon could get slowed down slightly by the interference with other particles (including particles in the vacuum) and that neutrinos could get slowed down more slightly by their interference terms with other particles. And that way we could get neutrinos traveling faster than the speed of light and special relativity could remain intact. (In this description of the universe we can do what used to seem impossible, we can boost into the rest frame of a photon. What would it mean to do that? Well I suppose it would mean that in this frame the photon would have to be an off-shell massive particle at rest.)

The SN 1987 supernova, a rich source of slower than light electron neutrinos (Hubble, ESA/NASA)

Now I’ll sit back and see people smarter than I am pick holes in the argument. That’s okay, this isn’t intended to be a serious post, just a bit of fun! There are probably predictions of all kinds of weird effects such as shock waves and time travel that have never been observed. And there are plenty of bits I’ve missed out such as the muon neutrinos traveling faster than electron neutrinos. It’s not often we get an excuse to exercise our analytic muscles on ideas like this though, so I think we should make the most of it and enjoy playing about with relativity.

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New Information on “FTL Neutrinos”

Thursday, February 23rd, 2012

We have new information, but my position on the OPERA experiment’s FTL neutrino measurement hasn’t changed.

First, here’s what we know. Members of the OPERA experiment has been working diligently to improve their measurement, better understand their uncertainties, and look for errors. Yesterday, the discovery of some possible problems was leaked anonymously (and vaguely) in Science Insider. This compelled OPERA to release a statement clarifying the status of their work: there are two possible problems, which would have opposite effects on the results. (Nature News has a good summary here.)

The important thing to learn here, I think, is that the work is actually ongoing. The problems need further study, and their overall impact needs to be assessed. New measurements will be performed in May. What we’ve gotten is a status update whose timing was forced by the initial news article, not a definitive repudiation of the measurement.

Of course, we already knew with incredible confidence that the OPERA result is wrong. I wrote about that last October, but I also wrote that we still need a better understanding of the experiment. Good scientific work can’t be dismissed because we think it must have a mistake somewhere. I’m standing by that position: it’s worth waiting for the final analysis.

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From left: Fermilab Deputy Director Young-Kee Kim; Gina Rameika, PPD; Kevin Bomstad and Jason Whittaker, Whittaker Construction and Excavation; Dixon Bogert, Fermilab; Mike Weis, DOE; Fermilab Director Pier Oddone; Erik Gottschalk, PPD. Photo: Reidar Hahn

This article first appeared in Fermilab Today on Jan. 24.

Despite the biting cold and snow, scientists and Fermilab personnel gathered outside to break ground for Fermilab’s new Liquid Argon Test Facility. The facility, expected to be completed spring 2013, will house liquid-argon based experiments.

Scientists have speculated since the 1980s that liquid argon could be used as a crash pad for high-energy neutrinos and have subsequently constructed several liquid-argon neutrino detectors; the largest and most prominent being ICARUS, the Imaging Cosmic And Rare Underground Signals, detector in Italy. The design of the new MicroBooNE experiment improves upon technology developed for ICARUS and will allow scientists to observe neutrinos with greater precision and resolution.

Regina Rameika is the project manager for the construction of the MicroBooNE detector.

“The MicroBooNE detector that will first use this facility is smaller than ICARUS, but incorporates some advanced designs,” Rameika said.

MicroBooNE will use liquid argon as a target for neutrinos generated in the Booster neutrino beam. When the neutrinos hit the argon nuclei, they generate showers of charged particles that then drift to an electrical detector. The purer the argon, the further the particles are able to drift. MicroBooNE will use ultrapure argon to maximize the distance these particles drift. This model is more efficient, cost effective, and has the potential to be scaled-up to a much larger size than previous detectors.

The MicroBooNE experiment will provide another layer of data for using the Booster neutrino beam. Not only will scientists be able to observe particles with the existing MiniBooNE detector, but now they will be able to measure neutrinos from the Booster neutrino beam with a second, higher-resolution detector.

“The MicroBooNE experiment will be focused on understanding some anomalies observed in the data from the MiniBooNE experiment,” Rameika said. This project will also provide valuable insight into different designs for liquid-argon detectors that could be located in the LArTF once MicroBooNE is complete.

—Sarah Charley

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Fermilab planning a busy 2012

Tuesday, January 3rd, 2012

This column by Fermilab Director Pier Oddone first appeared in Fermilab Today Jan. 3 .

We have a mountain of exciting work coming our way!

In accelerator operations, we need to give enough neutrinos to MINERvA to complete their low-energy run, enough anti-neutrinos to MiniBooNE to complete their run and enough neutrinos to MINOS to enable their independent neutrino velocity measurement that will follow up on last year’s OPERA results. We need to provide test beams to several technology development projects and overcome setbacks due to an aging infrastructure to deliver beam to the SeaQuest nuclear physics experiment. And we need to do all of this in the first few months of the year before a year-long shutdown starts. During the shutdown, we will modify the accelerator complex for the NOvA era and begin the campaign to double the number of protons from the Booster to deliver simultaneous beams to various experiments.

In parallel with accelerator modifications, we will push forward on many new experiments. The NOvA detector is in full construction mode, and we face challenges in the very large number of detector elements and large mechanical systems. Any project of this scale requires a huge effort to achieve the full promise of its design. We have the resources in our FY2012 budget to make a lot of progress toward MicroBooNE, Mu2e and LBNE. We will continue to work with DOE to advance Muon g-2. All these experiments are at an important stage in their development and need to be firmly established this year.

At the Cosmic Frontier, we will commission and start operation of the Dark Energy Survey at the Blanco Telescope in Chile, where the camera has arrived and is being tested. In the dark matter arena we will commission and operate the 60 kg COUPP detector at Canada’s SNOLAB and continue the run of the CDMS 15 kg detector in the Soudan Mine while carrying out R&D on future projects. We continue to have a major role in the operation of the Pierre Auger cosmic-ray observatory. In addition we should complete the first phase of the Fermilab Holometer, which will study the properties of space-time at the Planck scale.

At the Energy Frontier, we play a major role in the LHC detector operations and analysis. It should be a fabulously exciting year at the LHC as we push on the hints that we already see in the data.

Beyond construction and operation of facilities we continue our R&D efforts on the superconducting RF technology necessary for Project X and other future accelerators. We will be building the Illinois Accelerator Research Center and moving forward to connect our advanced accelerator program with industry and universities. Our rich program on theory, computation and detector technology will continue to support our laboratory and the particle physics community.

If we accomplish all that is ahead of us for 2012, it will be a year to remember and celebrate when we hit New Year’s Day 2013!

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