CMS prepares for the future

Three years after resuming operation at a centre-of-mass energy of 7 TeV in 2010 and ramping up to 8 TeV last year, the LHC is now taking a break for its first long shutdown, LS1. During the long period of highly successful running, the CMS collaboration took advantage of the accelerator’s superb performance to produce high-quality results in a variety of physics analyses, the most significant of which being the joint discovery with ATLAS of a new, Higgs-boson-like particle in July 2012.

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Supernova origin of galactic cosmic rays confirmed

The first direct evidence that galactic cosmic rays are accelerated within supernova remnants has been provided by observations by the Fermi Large Area Telescope collaboration. The results make use of four years of data collected by the telescope observing two supernova remnants – IC 443 and W44 – within our galaxy. The observations fit very neatly with predictions of neutral pion decay.

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Muon-capture measurement backs QCD prediction

The rate at which protons capture muons has been accurately measured for the first time by the MuCap collaboration at the Paul Scherrer Institute (PSI) in Switzerland. This process, which can be thought of as beta decay in reverse, results in the formation of a neutron and a neutrino. The team has also determined a dimensionless factor that influences the rate of muon capture, which was found to be in excellent agreement with theoretical predictions that are based on very complex calculations.

Muons are cousins of the electron that are around 200 times heavier. Beta decays demonstrate the weak nuclear force in which a neutron gets converted into a proton by emitting an electron and a neutrino. Now, replace the electron with the heavier muon and run the process backwards: a proton captures a muon and transforms into a neutron while emitting a neutrino. This process – known as ordinary muon capture (OMC) – is crucial to understanding the weak interaction involving protons.

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BaBar makes first direct measurement of time-reversal violation

The BaBar collaboration has made the first direct observation of time-reversal (T) violation. The results are in agreement with the basic tenets of quantum field theory and reveal differences in the rates at which the quantum states of the B0 meson transform into one another. The researchers say that this measured lack of symmetry is statistically significant and consistent with indirect observations.

The BaBar detector at the PEP-II facility at SLAC in California was designed to study the collisions of electrons and positrons and to determine the differences between matter and antimatter. In particular, physicists working on the experiment are interested in the violation of the charge–parity symmetry (or CP violation). Although the detector was decommissioned in the spring of 2008, data collected during the period of operation continue to be analysed.

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Students “hangout” with CMS physicists on Google+

The Compact Muon Solenoid experiment at the LHC [CMS] recently organised two virtual visits to the CMS experimental cavern, around 100 meters underground, using the Google+ Hangouts platform. Schools, universities and interested members of the public were invited to remotely connect with physicists in front of the CMS detector and in the above-ground control room, to talk about the detector, the LHC, and the physics goals of the collaboration.

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The CMS experiment puts physics onto the menu

When the LHC operates at peak luminosity, about a 1000 million interactions will be produced and detected each second at the heart of the CMS experiment. However, only a tiny fraction of these events will be of major importance. As in many particle-physics experiments, a trigger system selects the most interesting physics in real time so that data from just a few of the collisions are recorded. The remaining events – the vast majority – are discarded and cannot be recovered later. The trigger system, therefore, in effect determines the physics potential of the experiment for ever.

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Death by spitting [archives]

[This piece was originally hosted on my now-defunct MA course blog.]

The last few weeks have flown by, and it is now time for me to return to London. However, there was a story I read in the papers the day I landed in Bombay that I want to tell you about.

For those who are unfamiliar with us Indians, you should know that we abhor clean surfaces, vertical or horizontal. And so, we do our very best to spoil these clean surfaces in a variety of artistic ways. The most common method, picked up in school, involves dropping whatever waste we have onto the streets as we walk. This includes candy wrappers, chips packets, peanut cones and leaflets handed out to us outside malls.

However, for those pesky vertical surfaces, mere littering isn’t enough – Gravity plays spoilsport. Here’s where the subject of this post comes in – spitting! Spitting in public is a form of art in India, with skilled artisans peppering our walls and streets with red, paan-based projectiles, whilst avoiding the millions of people who live on, adjacent to and under the streets of the city.

One such skilled spitter recently lost his life when he spat out of the window of his home, illegally constructed too close to the overhead electricity cables. His red-coloured saliva made contact with the cables and the electricity pulled him out of the window, electrocuting him. He was declared dead on admission, when taken to a nearby hospital.

Some people I spoke to expressed shock at his death, pointing to the dangers that these brave artists face each day in defacing and polluting the city we all call home. Others vowed to continue his brave work, with many deciding to take up paan-chewing, often described as a disgusting habit.

Some ardent fans of the man’s work have rightly blamed the companies who installed the high-tension cables for providing electricity to the city, claiming that it was an elaborate plan by the elite to stamp out all alternative forms of artistic expression.

Alas, if the elite succeeds, our bare, ugly surfaces will become commonplace, and we will be forced to view the original layer of paint on them. Alas, given the number of artists in the city, this looks very unlikely.

Where are my microscopic black holes, eh? [archives]

[This piece was originally hosted on my now-defunct MA course blog.]

So, the Large Hadron Collider (LHC) smashed protons at a combined energy of 7 Tev yesterday. It was quite cool, and was possibly the largest collective orgasm physicists have ever had. But I am very disappointed, and you might have guessed why.

Some of you may know that a bunch of people (very, very few of them physicists) “predicted” that the world would be consumed in a microscopic black hole if the LHC smashed protons at very high energies. Here’s a sample from The Sun:

German chemist Otto Rossler has filed a complaint with the European Court Of Human Rights – although he thinks the test will take a little longer to kill us.

He claimed: “Nothing will happen for at least four years. Then someone will spot a light-ray coming out of the Indian Ocean.

“A few weeks later we will see a stream of particles coming out of the soil on the other side of the planet. Then we will know there is a little quasar inside the planet.

“The weather will change completely, wiping out life. There will be a Biblical Armageddon.”

Yes, you read it right. A chemist. Not a particle physicist. A chemist who seems to know exactly where the “quasar” will appear.

I really don’t see the point of attempting to highlight all the flaws in that statement, but I must bring to your attention the amused look I had when I read the word “quasar”. A quasar or a quasi-stellar radio source is a very distant, highly energetic galaxy. These quasars do have active galactic nuclei that may be made of black holes, but that is not related to the microscopic black holes that will supposedly form when the LHC starts smashing protons at even higher energies.

Coming back to my disappointment, I was thoroughly shattered when I found that the LHC hadn’t. Well, it did shatter some records, but it didn’t destroy the earth.

Of course, I am not like this guy:

Disaster Voyeurism. Source:

Disaster Voyeurism. Source:

Sometimes, I feel a little sorry for the people who spread such unjustified fears in society, especially when they are rubbished by the experiments they fear. At those times, I remember the girl who committed suicide in India because she was fed nonsense by the TV channels and didn’t want to be around when the earth would crack up and swallow the village.

Don’t feel sorry for them. Their fear might have its reasons, but spreading it to such an extent that someone is prompted to take their own life is unacceptable.

Although, somehow, science gets actively discussed only when there is some negative chatter around the topic. I don’t see that as a bad thing, necessarily, but I wonder where these debates should be held and how the public should be informed.

While we discuss this, I’m still waiting for my microscopic black holes.

Seeing beyond VIBGYOR [archives]

[This piece was originally hosted on my now-defunct MA course blog.]

Ah, the human species. For all our coolness, we can’t do what a little mantis shrimp can – see beyond the VIBGYOR spectrum of light. The mantis shrimp has what scientists call hyperspectral colour vision, something that ESA’s ExoMars rover’s camera eyes will have. Essentially, hyperspectral imaging allows a camera to view not just the visible-to-humans spectrum but also the infrared and ultraviolet bands.

Check out a simulation of the ExoMars rover, designed to drill into the Martian surface in search of subterranean life.

So, why exactly have I started talking about funky shrimps and Mars rovers? Well, this morning, we had a lecture by Lewis Dartnell who is an astrobiologist. [Cue: “Oooh!”] During the break, Dr Dartnell, who is working on some aspects of the ExoMars rover, mentioned the hyperspectral imaging camera and set my mind thinking.

I began to think of what it might mean if we were able to see light on either side of the VIBGYOR spectrum.

For starters, human history might have taken a very different route. Think of the importance of night vision in modern urban warfare – the goggles detect infrared (IR) light emitted by enemy combatants. Remember the scene from Predator where the alien kills the humans by detecting their body’s infrared radiation? Now, imagine how the various ambushes planned by the various warriors of antiquity might have panned out if all the people could detect their opponents by their body heat!

Warriors could also use their ultraviolet (UV) vision to spot blood and use it to track down their enemies. This, of course, is under the assumption that the same mechanism that would allow us to see UV radiation doesn’t cause us to go blind from over-exposure to Sol’s UV light. Of course, since the insects and birds survive fine, I don’t see a reason to assume that it would do us physical harm.

Think, also, of the lack of privacy and the social structure in which the humans would have evolved. Rudimentary huts wouldn’t have been adequate to hide lovers from the eyes of their families, equipped with IR vision! Would we, as some primates do, have indulged in public displays of more than just affection? I believe clothes would only be worn to protect oneself from the elements, and not to protect one’s modesty, whatever that term might mean in a society capable of infrared vision. Human history and sociology might have been very different, only if we saw differently.

Wikipedia informs me (as do another couple of sources) that many insects are aided in their flight navigation by the ultraviolet radiation from celestial bodies. I’m not sure about the veracity of these claims, but assuming they were true, I imagine that the way in which we went about exploring this planet of ours might have been rather interesting.

Another thought that occurred to me involved the nature of art. I imagine that with a larger palette of colours at our disposal, artists would have found unique methods of expressing themselves. I’m not sure I can imagine what this might have been like, but the possibility for art, photography and filming seems very fascinating.

“But what about the downsides?” I hear you ask. Surely there are a few. I think the one that hits me squarely between the eyes involves our perception of hygiene. Human urine, like the urine of cats, dogs and rodents, glows in ultraviolet light. My first thought was something along the lines of, “Eew!” Eloquent, yes. The thought of being able to see the glow of urine isn’t a pleasant one, and I was tempted to classify it as a downside.

Then a thought struck me.

Our ancestors might not have had the plague, since rat urine might have told them where the mice lived and bred. Who knows what the population of the world would have comprised of?

In addition, we have evolved socially to consider the act of urinating a private one (albeit shared with hundreds of people of the same sex, over the course of our lives). We consider it disgusting to urinate anywhere other than a toilet. We might call the perpetrator uncultured. This, of course, is the “we” that has evolved in the absence of UV vision. If the progenitors could see urine glowing, I think our social dynamic might have been slightly different. Thinking of all the animals that mark their territory with their fluids, I think one of two things might’ve occured:

  1. We would still live in what we define as a cultured society, but without the pets we keep – no cats and no dogs.
  2. We would turn into one of those species that marked our territories with urine. Landscaping would’ve have looked SO weird.

Anyway, I’m not sure what all the consequences would be if we were able naturally to see a range of colours beyond VIBGYOR, but at least we now have the technology to explore these spectra.

LHC’s world record [archives]

[This piece was originally hosted on my now-defunct MA course blog.]

First collisions at LHC at 7 TEV! The two beams are at 3.5 TEV each and everything is cool!

CERN has a live webcast here1.

Check out CERN’s latest tweets as well as the conversation people are having about theLHC.

[Standard declaration: I am not responsible for the content from external sources. People may use the hashtag to spam, but there’s also some real conversation happening.]

I’m all whee! :D

  1. Please note that, as of the date of republishing this archived post, the webcast is no longer available. In lieu, here are some clips from the day: The high-energy collisions at 7 TeV, building 40, 30th March 2010, LHC News April 2010 : LHC First PhysicsLHC first physics : clip resume of the day March the 30th, 2010 []