Merged Puzzling results from CERN

[ceptimus]

There's a small correction factor needed due to Earth's rotation. The detector is experiencing centripital acceleration towards the Earth's axis, and a component of that acceleration is towards the direction of the particles.

However, this effect is far too small to account for the alleged early arrival of the neutrinos.

 

[Michael Mozina]

I have a slightly different take on this: surely almost as soon as they'd started giving such talks the press would have got hold of it, and (to avoid only pure nonsense appearing in the press) they would have essentially been forced to make a press release. So it seems sensible to do both at the same time.

But given that they've apparently done 6 months checking, why not wait slightly longer and release the detailed analysis at the same time? I would have expected something like the current paper plus a 100 page (or whatever) appendix giving details of the kinds of things people asked about at the presentation, and giving enough detail of the statistics etc to give people a chance to check things.

I tend to agree with you. Sol might be being a little too hard on them. It seemed to me they did everything they could to suggest that the results were likely due to an error that they couldn't find themselves. They made it very clear that they were asking for help in finding a likely error.

I'm confident that the press would have latched on to the results either way. I think they did their best to try to explain to the press that it was most likely an oversight on their part, not something that was likely to overturn the laws of physics as we understand them. I think the lead writer offered to eat his own shorts if there isn't an error of some kind that was found in fact.

I don't really know what else any group in their position might do once they reach the point where there aren't a lot more answers internally other than to ask for help.

 

[Meridian]

Thanks Sol, the link you posted does not seem to work, here's a correct link:

http://www.guardian.co.uk/science/life-and-physics/2011/sep/24/1?

That's a very interesting article. I wonder whether it's in the actual paper, or just a blog associated to it. (It seems much too sensible for anything science-related in a newspaper!)

The particular issue about potential correlation between production time and beam angle was raised in the Q&A, but (from a non-expert point of view) the speaker just asserted that there was no such effect - he didn't give a comprehensible account of how he knew this. He did seem to indicate that the beam spread is mostly from the dynamics of the decay, implying that the angular variation of the protons hitting the target is much smaller, and did talk about the spot size on the target, but didn't convert that to angles or quantify possible correlations, e.g., with the switching on and off of the proton beam.

 

[Meridian]

There's a small correction factor needed due to Earth's rotation. The detector is experiencing centripital acceleration towards the Earth's axis, and a component of that acceleration is towards the direction of the particles.

However, this effect is far too small to account for the alleged early arrival of the neutrinos.

Presumably at some point they will have to produce a much longer paper with all sorts of effects like this listed and quantified (or just shown to be negligible). Personally though I expect them to get these things right: the mostly likely source of error seems to me to be associated to the statistics, and (probably as yet unidentified) possible biases affecting that. There again, presumably they will have to give a detailed account of these at some point.

 

[RecoveringYuppy]

You should really watch the video or have attended like sol Watching the video really increased my understanding; perhaps from 5% to 10%

Yes, the mountain reduces the amount of background noise.

Well, I didn't see the video so maybe it answers my question, but I wasn't referring to background. "background" shielding is obviously the whole purpose of burying the lab at Gran Sasso. I was referring to filtering out particles produced at CERN as side effects of producing the neutrinos.

 

[Speed of Light]

There's a small correction factor needed due to Earth's rotation. The detector is experiencing centripital acceleration towards the Earth's axis, and a component of that acceleration is towards the direction of the particles.

However, this effect is far too small to account for the alleged early arrival of the neutrinos.

Rotation also alters the trajectory.
What about the earth's rotation around the sun?

 

[RussDill]

Rotation also alters the trajectory.
What about the earth's rotation around the sun?

There is no acceleration afaik, its just following a geodisc.

 

[Lennart Hyland]

When I read about the mass of the neutrino on wiki they use eV.. why dont they use kg?

 

[MattusMaximus]

When I read about the mass of the neutrino on wiki they use eV.. why dont they use kg?

Because to particle physicists energy and mass are practically interchangeable (because of E=mc²). The value of eV is units of energy, presumably divided by c² (speed of light squared) which can give you units of mass.

 

[ServiceSoon]

Well, I didn't see the video so maybe it answers my question, but I wasn't referring to background. "background" shielding is obviously the whole purpose of burying the lab at Gran Sasso. I was referring to filtering out particles produced at CERN as side effects of producing the neutrinos.

Oh. In other words how do they know they are detecting neutrinos and not something else? I don't recall that this was presented as a concern at the Q&A. Unfortunately, I can't explain why that is. My smart ass answer is that the detector is a neutrino detector. I suppose that means it detects neutrinos only.

There's a small correction factor needed due to Earth's rotation. The detector is experiencing centripital acceleration towards the Earth's axis, and a component of that acceleration is towards the direction of the particles.

However, this effect is far too small to account for the alleged early arrival of the neutrinos.

Can you show your math? I ask that because I don't think this is a real concern. If anything they would have to aim the death ray laser higher than the target so it ended up hitting the detector. I’m thinking in terms of bullet drop…. Besides, if the neutrino drops then it would have to travel a longer distance so if they didn’t calculate for this it would have showed a slower speed. Speed = time/distance. What say you?

When I read about the mass of the neutrino on wiki they use eV.. why dont they use kg?

The mass is so negligible (zero) that they often us it's energy equivalent instead, electron volt. Has the scientific community came to agreement that the neutrino has any mass? I don't think so.

 

[RussDill]

Because to particle physicists energy and mass are practically interchangeable (because of E=mc²). The value of eV is units of energy, presumably divided by c² (speed of light squared) which can give you units of mass.

Why would you do this? What is wrong with you? "Presumably"? You could have just taken 5 seconds to look it up.

 

[rwguinn]

Seems to me there are a lot of ways for error to build up, not unexpectedly. Asking for help is a decent way to find it, if so.
Quick question--Are the 3-D coordinates from GPS that good (We're talking parts per billion, here, I gather) considering that the orbits are not exactly perfect circles/elipses due to all the little differences in mass distribution in the Earth?

 

[edd]

The mass is so negligible (zero) that they often us it's energy equivalent instead, electron volt. Has the scientific community came to agreement that the neutrino has any mass? I don't think so.

It's pretty much agreed they have a tiny mass, but the masses haven't been nailed down very well.

 

[MattusMaximus]

Why would you do this? What is wrong with you? "Presumably"? You could have just taken 5 seconds to look it up.

Or, I could have just typed it out in zero seconds because I already knew that's how particle physicists look at the mass of particles

 

[RussDill]

Or, I could have just typed it out in zero seconds because I already knew that's how particle physicists look at the mass of particles

That isn't an electron volt. An electron volt is the energy gained by a particle with an elementary charge of 1 is accelerated through 1 volt.

 

[MattusMaximus]

That isn't an electron volt. An electron volt is the energy gained by a particle with an elementary charge of 1 is accelerated through 1 volt.

Yes, and electron-volts are units of energy (E), which when divided by the speed of light squared (c²) gives you units of mass (m), via

E = mc²
m = E / c²
Looking at the mass of fundamental particles in units of eV/c² is pretty standard practice in particle physics. And, depending upon which system of units you use, sometimes c = 1, so the mass looks like it is in units of eV.

Get it now?

 

[nvidiot]

From wiki:

By mass-energy equivalence, the electron volt is also a unit of mass. It is common in particle physics, where mass and energy are often interchanged, to use eV/c2, where c is the speed of light in a vacuum (from E = mc2). Even more common is to use a system of natural units with c set to 1 (hence, E = m), and simply use eV as a unit of mass.
For example, an electron and a positron, each with a mass of 0.511*MeV/c2, can annihilate to yield 1.022 MeV of energy. The proton has a mass of 0.938 GeV/c2, making a gigaelectronvolt a very convenient unit of mass for particle physics.
1 GeV/c2*= 1.783×10−27 kg
The atomic mass unit, 1*gram divided by Avogadro's number, is almost the mass of a hydrogen atom, which is mostly the mass of the proton. To convert to megaelectronvolts, use the formula:
1 amu*= 931.46 MeV/c2*= 0.93146 GeV/c2
1 MeV/c2*= 1.074×10−3 amu

 

[RecoveringYuppy]

Oh. In other words how do they know they are detecting neutrinos and not something else? I don't recall that this was presented as a concern at the Q&A. Unfortunately, I can't explain why that is. My smart ass answer is that the detector is a neutrino detector. I suppose that means it detects neutrinos only.

Actually, I doubt the neutrinos are detected directly. More likely they are directly detecting tau leptons. Either way, I expect a stream of any other high energy particle would swamp the dectector, most detectors are like that. I woul expect that the direction the particle is travelling is probably the strongest indicator there is that they have a relevant event. So I'm wondering if, in this case escpecially, the mountain is a necessary part of fitlering out particles produced as side effects of producing the neutrinos.

 

[dasmiller]

Seems to me there are a lot of ways for error to build up, not unexpectedly. Asking for help is a decent way to find it, if so.
Quick question--Are the 3-D coordinates from GPS that good (We're talking parts per billion, here, I gather) considering that the orbits are not exactly perfect circles/elipses due to all the little differences in mass distribution in the Earth?

FWIW, the GPS orbit ephemeris parameters don't assume perfectly elliptical orbits. There are actually 9 terms IIRC, whereas an ideal elliptical orbit can be completely specified with 6.

 

[RussDill]

Yes, and electron-volts are units of energy (E), which when divided by the speed of light squared (c²) gives you units of mass (m), via

E = mc²
m = E / c²
Looking at the mass of fundamental particles in units of eV/c² is pretty standard practice in particle physics. And, depending upon which system of units you use, sometimes c = 1, so the mass looks like it is in units of eV.

Get it now?

Yes, but your statement explained this in a rather poor manner.

Because to particle physicists energy and mass are practically interchangeable (because of E=mc2). The value of eV is units of energy, presumably divided by c2 (speed of light squared) which can give you units of mass.

An eV is not a unit of energy divided by c^2. It can, just as any unit of energy, *be* divided by c^2 to give units of mass. Joules could just have easily been used, but eV are used by particle physicists because they enjoy accelerating charged particles through a potential difference.