Friday, March 16, 2012

ICARUS: the neutrino speed discrepancy is 0, not 60 ns

The OPERA detector originally detected neutrinos that were arriving to the Gran Sasso cavern (or tavern) in central Italy 60±10 nanoseconds too early after their 730-kilometer (2.4 milliseconds) trip from CERN. If that were so, they would have been 0.0025% (25 ppm) faster than light in the vacuum.

Many of us remained sane and realized that this can't happen; it follows that the OPERA was out-of-tune. And indeed, the mistake was found in the timing: loose cables and wrong interpolation in the GPS synchronization procedures have to be blamed for up to 100 ns and dozens of ns in the opposite direction. (And maybe other things they haven't found or announced yet were wrong, too.)

Even though some physicists incredibly enough remain ambivalent, it's clear that most of the discrepancy – to say the least – has gone away (and will officially go away once the new paper is published) and there's no credible experiment at this moment that would indicate a neutrino's heresy against Einstein's commandments. The only question is how accurately OPERA will manage to measure the speed of light in their corrected paper but I am not too interested in that given the fact that they're able to produce a 60-nanosecond error, anyway.

OPERA – whose real job should be neutrino oscillations and not sensational, wrong claims about relativity – still tries to look very important so we must wait for their new precise results (hopefully more precise than the previous ones). However, there is one guy who can already measure the right speed today and who has actually published a preprint with the right figure. Who's that?



Yes, his name is ICARUS. Nice to meet you. A few thousand years ago, he had a company that later evolved to the Aegean Airlines Greece. But because the Greeks no longer have to work – they have invented a financial perpetual motion machine (a printer of worthless government bonds that some people exchange for the real money) that replaces work and produces lots of money even after you die – ICARUS retired and lives in the cave in Gran Sasso, very close to OPERA. What a coincidence. ;-)

You may ask whether OPERA and ICARUS are friends if they share a cave. But the answer is that your friend is not your neighbor but the guy behind him. And the paper I am going to present is another anecdotal proof of the proverb. Even though ICARUS is emeritus, he (together with his 50+ employees) just published his measurement of the neutrino speed. What did he find?




ICARUS (which stands for "Imaging Cosmic And Rare Underground Signals") contains 600 tons of liquid argon and detects neutrinos via the reaction \[

{}^{40}{\rm Ar} + \nu \to {}^{40}{\rm K} + e^-

\] By the beta/weak process above, some neutrinos transmute the argon nuclei to... no, it's not krypton although it rhymes with argon. Instead, it's kalium that is called "potassium" in English for reasons I find incomprehensible (especially because both words sound totally Latin) but they have something to do with potash (why don't you just call it "draslík" just like everyone I know and I have ever communicated with on this element?). The number of neutrinos they can detect is smaller than for OPERA. But they still observed seven neutrinos from the same production center (CERN-SPS) that is used by OPERA and published the resulting speed in
Measurement of the neutrino velocity with the ICARUS detector at the CNGS beam
At this moment, you must be growing impatient: why this Lumo keeps on babbling? Can't he just tell me the result? And you're right. The result is \[

\delta t = (0.3 \pm 4.0_\text{stat}\pm 9.0_\text{syst})~{\rm nanoseconds}.

\] Within the error margin which is almost exactly the same as OPERA's error margin, around 10 nanoseconds in total (in the Pythagorean way: but unlike OPERA, ICARUS says that most of the error is systematic), they get an exact agreement with relativity. The discrepancy is so small relatively to the error that I won't even study in which way it goes (subluminal vs superluminal). The neutrinos propagate by the speed of light in the vacuum up to the (relative) accuracy of a few parts per million. Let me just mention that due to their finite rest mass, the neutrinos don't quite move by the speed of light but the difference is of order \(c-v\sim 10^{-20}c\) which isn't measurable for any beams going from one place of the globe to another. If you don't know how I got this small number, note that the rest mass \(m_{\nu0}c^2\lessapprox 0.1\eV\) and the actual energy of these multi-GeV neutrinos is \(E\gtrapprox 10^9\eV\) so \[

\eq{ \gamma &=\frac{1}{\sqrt{1-v^2/c^2}} = \frac{E}{m_{\nu 0}c^2} \\
\gamma& \gtrapprox 10^{10} \\
1-\frac{v^2}{c^2} &\lessapprox 10^{-20}\\
\frac{c-v}{c} &\lessapprox \frac{1}{2}\times 10^{-20}
}

\] ICARUS has previously falsified OPERA's claims in November 2011, by an indirect method. They showed the absence of some crazy Cherenkov-like radiation that would have to be produced by hypothetical superluminal neutrinos, as pointed out by Cohen and Glashow. If you accept the Cohen-Glashow assumptions, they showed that the speed discrepancy had to be at least 1,000 times smaller than claimed by OPERA.

I personally think that further experiments on this topic are a waste of time and money. We've had a potentially exciting effect for a few months (and many physicists got infected by the laymen's media emotions connected with the chance to humiliate Albert Einstein) but it has evaporated and it will never return again, OK? So let's move on. Real discoveries may be waiting for us.



Neutrino and communication

By the way, the Physics arXiv blog discusses a preprint about the first successful transfer of a digital message using neutrinos, something that could be useful for the submarines.



LHC: back to work

The proton beams began to circulate in the LHC tubes again, on 3/14 approximately at 3:14:15.926535897932384626. OK, the time isn't accurate but at least it's \(\pi\) and OPERA wasn't accurate, either. The collisions at 8 TeV, 50 ns should restart on April 7th or so.

5 comments:

  1. Dear Luboš,
    I understand that you don't like what is happening in Greece (I don't either), but please try to be objective: The Greek crisis is not a result of Greeks being lazy.

    In fact Le Monde [1] refers to a study by Patrick Artus of Natixis that Greeks work almost twice as much as Germans. Greeks have a higher work hour schedule than other European countries. I also say with reservation that the study might not reflect accurately the non official work hours of people working 2nd and 3rd jobs, trying to make ends meet.

    [1] http://toutsurlachine.blogspot.com/2011/06/non-les-allemands-ne-travaillent-pas.html (Le Monde seems to be closed without subscription) I have seen many other similar statistics by others (in greek), please search the web.

    Konstantinos Anagnostopoulos
    Fellow physicist, reader of your blog (thank you), National Tech U Athens.

    ReplyDelete
  2. Dear Konstantinos,

    thanks for your comment and attention. These sentences about working hours may sound like emotionally or bureaucratically relevant arguments but they're not really relevant for the fiscal problem.

    At the end, what the "staggering life in Greece beyond your means" means is that you spend (vastly, by a factor of 2-3) more than you produce when expressed as financial amounts. This discrepancy has various reasons, including bad discipline in taxation, pensions, and all these things.

    However, even the employment and work discipline is just catastrophic in your country, regardless of some artificial criteria counting the "hard work" of e.g. the Greek bureaucrats. First of all, your comment completely neglects 21% of the working force that is unemployed - it doesn't work at all but it often gets all kinds of incredible support from the government that is higher than our average salary (!). Among the youth, the percentage of unemployed stands above 51%. Not shocking if all these people are doing well, anyway.

    But even those who are employed predominantly do no useful work. The public sector represents something like 1/2 of the employed people in Greece which is horrible because they are, from a financial viewpoint, as unproductive as the unemployed ones, and they often actually harm the tiny private sector in Greece by trying to regulate it or otherwise harass it. You are counting as "hard work" by your nonsensical criteria all kinds of activities for which the people should be arrested under normal healthy conditions in which the productive people actually have their say.

    These comments don't mean that the tiny private sector in Greece is healthy. It's not healthy, either: it mostly produces things that can only be sold to the heavily overpaid Greek pensioners and employers of the bloated public sector but would be uncompetitive in the world markets. That's why the prices of everything are higher than they should be and the GDP of everyone, including the private sector, is heavily overstated by the official numbers.

    The result of all this mess is that Greece, a country that has never gone through the "official" Soviet-like communism and that has higher unemployment benefits than salaries in Czechia, exports 6 times less than Czechia (the same population), a country screwed by 40 years of full-fledged communism, does. And this is despite the fact that our situation is far from perfect and even our pensions etc. are not guaranteed to be sustainable. That's just one number. One may compare lots of quantities that actually matter with many other countries and it's just scary.

    After decades of de facto hardcore socialism, your country clearly needs much deeper reforms than we needed after the fall of communism in 1989. You will surely need a 50% reduction of various pensions/social_fees/salaries in the public sector etc. The main problem with your nation is that most of you live in a complete denial of this fact. You're trying to look for errors in someone else and your comment is just another anecdotal evidence of this horrifying fact, the main fact that will make the Greek problem a long-term one.

    Best wishes
    Lubos

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  3. Konstantinos, i have not met a person from Greece in my whole life that does not have a socialist or communist ideology. Everyone in Greece believes in big government, no matter what political party they belong to.

    Even if the Greeks that have a job, work more than Germans, that they do not, is not very relevant. One of the problems in Greece is that people think they deserve the salaries in Germany and Norway and that they should have a similar welfare state with rich European countries. They do not understand that they are not Norway that has lots of oil and 4 million population.

    Both in schools and university, the students are brainwashed that the government should give to them. The socialist system is the reason that the greek universities are in such a big mess.

    My brother studied there and he is really disappointed by it. Both the students and you the professors, not only support this system but you also think that it is the best system and best universities in the world. Probably the only ones that have anarchists living inside the classes of the university and students carrying molotovs instead of bags. It is normal to not have classes because of strikes for months and taking 8 years to get an undergraduate degree.

    Any politicians that did not promise things to the people would never win. If a politician told the truth to the greek people, his career would immediately stop. So i do not understand why you always blame the politicians for the crisis. You only vote for the people that say they will give things for free.

    There is a deep cultural problem in Greece that is the reason for the problem. Everyone feels sorry for Greece here but i really do not like people that others give money to them and all day they swear about the people that help them. You should be and deserved to be in a much worse situation.

    Although people in greece were poorer than most of europe before the crisis, they should have been even poorer. What they had before the crisis was more than they deserved and more than they produced. The salaries were low-they should have been even lower and there shouldn't have been lots of unnecessary jobs. This is why you do not see a crisis in China, their salaries are low and they don't force the government to give to them.

    You will go forward when you start having and supporting, the private sector, stop hating the rich and blaming and calling everyone a thief but yourselves. It is strange to not find a person from greece not accusing everyone else of being a crook and a thief and stealing from the people. This has always been, much before the crisis. And if someone supports some rules and some order, he is a fascist!

    If you really want to help your country, admit the mistakes it did instead of denying them.

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  4. Hi guys,

    I am not sure what you mean "spend (vastly, by a factor of 2-3) more than you produce when expressed as financial amounts" when the deficit without debt obligations is appx 5% (some exceptional years in the decade 2000-2009 exist but this will not make a huge difference below). The problem with greece is a humongous debt that results in debt obligations that surpass the scale of the annual budget. The annual budget is appx 50 bn and in 2012 the debt obligations will reach 80 bn, with similar figures in 2013 and 14. The usurious history of the greek debt is long and complicated and goes as deeply as in 1893! No one has made a serious analysis due to lack of data (this is why some of us have asked for an independent committee to access and analyze the relevant data). Some people claim that most of it is interest upon interest and obtained (in the full knowledgte of the lender) for illegal use through corruption. Many of us believe that it is illegal and we have to refuse to pay it, according to the international law.

    Some numbers that could be helpful is that salaries in the public sector and pensions is less than 26 bn euros over a 50 bn annual budget. I am sure you understand that reducing salaries at any possible rates will not remedy the situation. Inefficient as the public sector is, it still needs people to run it and I am not sure how much less can be spent on salaries of permanent personel. Normalized to the population, the amount spent in the public sector is less than in France, Germany and Italy. Contrary to the above, salaries of government personel (advisors of ministers, secretaries of ministries as well as the cost of ministers and MPs) is close to 5bn and I will be very happy to see it cut by a factor of 5 (it still does noe solve the equation).

    Also referring to unemployment benefits in Greece, I am not sure what the numbers are in Czechia, but a Greek unemployed person gets about 400 euros before tax for 12 months (then ... nothing). This is very low for European standards, and if it is less in Czechia, I really sympathize with this. It is certainly not enough to live a descent life when the rent for a 2 bedroom appartment (40-60 sq. meters) in Athens is more than 300 euros, imagine if you also have to support a family and pay the bills.

    In contrast, Greece has spent (mostly through borrowing) 110 bn euros for refinancing the banks since the end of 2009 (official declaration of E. Venizelos) and banks seem not to use the money for the good of the economy. There was an article by JP Morgan that an additional 25bn will be needed until 2013.

    As you see, the equation is unsolvable. You might want to look at some figures in a small post ay my blog
    http://knanagnostopoulos.blogspot.com/2012/03/to-my-european-friends-money-badly.html

    I am not trying to make anyone feel sorry for Greece, we are responsible and we will get out of this mess. You are right for many of the comments about the corruption of politicians, which is at the heart of today's public debt. We have paid roads, bridges, airports, electronic systems, military planes, submarines and tanks, olympic games ... 2 to 4 times their market value. We have been stupid for letting this happen, but extremely few Greeks were aware of the scale of the problem and these were not in the mainstream news. The system was happy, making very few people very rich (an estimate is 77000/10000000 Greeks), but the rest of us were living very moderate lives. So when the German government "punish" the Greek people to satisfy their voters, they punish the wrong people.

    Even if this is happening to Greece, it is still worthwhile to understand it as much as possible quantitatively, public debt is soon blowing in a country near you!

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  5. Dear Konstantinos,

    it is a nonsensical self-delusion to subtract the interest payments from your budget deficit to make it look smaller.

    They're a part of the environment in which Greece is operating and has to be operating. In Norway, they surely have higher heating bills in winter which doesn't mean that they should subtract them from various deficits.

    But even if you subtract them, saying that 5% of GDP is "normal and OK" is pathological. It may be OK once but 20 years of such debt creates, with interests, the debt of 160% of the GDP i.e. it creates your situation. Because you clearly mean that it's OK in the long term, you're wrong. 5% deficits would still fail to be OK. The opposite opinion is really the reason why you're KO.

    You: "In contrast, Greece has spent (mostly through borrowing) 110 bn euros for refinancing the banks since the end of 2009 (official declaration of E. Venizelos) and banks seem not to use the money for the good of the economy."

    Apologies but the banks are the healthiest and sanest part of your economy.

    You: "I am sure you understand that reducing salaries at any possible rates will not remedy the situation. Inefficient as the public sector is, it still needs people to run it and I am not sure how much less can be spent on salaries of permanent personel."

    I am sure you understand that I don't agree with a single word you say. The Greek public sector simply isn't doing work worth more than 50% of salaries so if someone doesn't like the 50% cut, he may still leave and/or commit suicide.

    Your comment that the public sector tumor needs to exist regardless of the amount of inefficiency in it is simply scary. People outside Greece don't understand how hopelessly morally corrupt your nation, including people at universities etc. where they should have a clue, is.

    Cheers
    LM

    ReplyDelete