Search found 49 matches

by adam_jeff
Mon May 19, 2014 9:10 am
Forum: The Accelerator
Topic: Repulsive gravity testing at the LHC?
Replies: 1
Views: 1706

Re: Repulsive gravity testing at the LHC?

Interesting idea. I am skeptical although I didn't go through the relativistic physics in detail. However, I can say that he makes a couple of pretty basic errors with regards to the LHC, which leads me to believe that he hasn't discussed the idea with anyone at CERN.
by adam_jeff
Wed Dec 12, 2012 3:54 pm
Forum: The Accelerator
Topic: Decay film
Replies: 2
Views: 2412

Decay film

I think some people here would enjoy Decay (http://www.decayfilm.com/) To be stressed that this is a work of fiction! However there's lots of nice location shots of CERN and it is surprisingly well filmed for an amateur movie (I am referring to the camera-work, not the acting, which is terrible. But...
by adam_jeff
Tue May 29, 2012 8:38 am
Forum: The Accelerator
Topic: 2012 Events Discussion
Replies: 100
Views: 79852

Re: 2012 Events Discussion

Beams just dumped on a 170 pb^-1 fill! Is this a record for the LHC so far? Now filling with a new scheme. Still 1380b, but few more expected bunch pairs at IP 1 and 5, (CMS/ATLAS) and a few less at point 8 (LHCb). Anyone know why the change? Yes a new record as announced here - https://twitter.com...
by adam_jeff
Mon May 07, 2012 12:05 pm
Forum: The Accelerator
Topic: Protons and Special Relativity
Replies: 8
Views: 5049

Re: Protons and Special Relativity

Yes, the mass of the protons certainly increases according to Einstein's equations, and that's why the protons don't speed up very much in the LHC - most of the added energy goes into extra mass, not extra speed. But that is mass not size. According to Special Relativity, a moving object will appear...
by adam_jeff
Thu May 03, 2012 8:23 am
Forum: The Accelerator
Topic: What's the rf cavity phasing for?
Replies: 3
Views: 1893

Re: What's the rf cavity phasing for?

Oh and the extra complication is that the LHC operates 'above transition' meaning that particles with more energy actually take longer to go round - you have to give an extra FORWARDS kick to the leading particles, and a backwards kick / less forwards kick to the trailing particles... accelerators a...
by adam_jeff
Thu May 03, 2012 8:21 am
Forum: The Accelerator
Topic: What's the rf cavity phasing for?
Replies: 3
Views: 1893

Re: What's the rf cavity phasing for?

That's right. The complication is that the beam itself places a 'load' on the cavities which changes the shape of the oscillation slightly. That's why when you increase the intensity you have to tweak the phase of the cavities to allow for the extra 'beam load'.
by adam_jeff
Thu Apr 19, 2012 8:04 am
Forum: The Accelerator
Topic: Why is there a difference in the Cms and Atlas luminosities?
Replies: 9
Views: 2848

Re: Why is there a difference in the Cms and Atlas luminosit

Analysing the van der Meer scans is not straightforwards and it will take some time before the results are known, and the calibration is applied to the luminosity monitors. Even then, ATLAS and CMS may not agree on the calibration. Already last year there was considerable disagreement on the integra...
by adam_jeff
Mon Apr 16, 2012 3:05 pm
Forum: The Accelerator
Topic: 2012 Events Discussion
Replies: 100
Views: 79852

Re: 2012 Events Discussion

There have been more programmed dumps this year so far, not because the machine is better but because the priorities are different. They are trying to increase the intensity back to 1380 bunches. To get there there are a number of milestones to pass and boxes to tick, in order to satisfy the Machine...
by adam_jeff
Thu Apr 05, 2012 1:02 pm
Forum: The Accelerator
Topic: Yellow Pipes
Replies: 1
Views: 1588

Re: Yellow Pipes

They're beam loss monitors (tip: there's a label just behind them!). Specifically, they are ionisation chambers. They work on the same principle as a Geiger counter: a tube of gas is subject to a high voltage (thus the warning signs). When any particles from the beam hit the beam pipe, they create a...
by adam_jeff
Fri Jan 27, 2012 9:30 am
Forum: Portal link and forum suggestions
Topic: Too many spam-bots
Replies: 11
Views: 5171

Too many spam-bots

In the last few months the forums seem to be more and more plagued by spam-bots. Maybe it's just more noticeable it because all the humans are quiet during the LHC tech stop. Obviously [some of] these bots are quite sophisticated and it's hard to think of a way of weeding them out automatically (For...
by adam_jeff
Wed Dec 14, 2011 9:35 am
Forum: Science
Topic: Higgs could be found before Christmas!
Replies: 26
Views: 6024

Re: Higgs could be found before Christmas!

ATLAS asked for 20 fb-1 in order to confirm (that's how much data they would need, if the Higgs is really around 125GeV, to get a 5 sigma discovery) which is at the optimistic end of the 2012 run.
by adam_jeff
Fri Nov 25, 2011 9:24 am
Forum: The Accelerator
Topic: Possible uses of Higgs Field
Replies: 1
Views: 1543

Re: Possible uses of Higgs Field

and hoverboards! The movies promised us hoverboards!
by adam_jeff
Fri Nov 18, 2011 1:00 pm
Forum: Science
Topic: Neutrinos go faster then light !
Replies: 109
Views: 96786

Re: Neutrinos go faster then light !

The so-called refutation by ICARUS is really nothing of the sort. They measured the neutrino energy spread (which had already been measured by OPERA anyway) and found that the neutrinos had not lost energy on their journey. This links back to an earlier 'refutation' by Cohen & Glashow which states t...
by adam_jeff
Fri Nov 04, 2011 9:52 am
Forum: The Accelerator
Topic: Is MD expected to be 25% completed?
Replies: 2
Views: 1578

Re: Is MD expected to be 25% completed?

That's right, the Hubner factor is the ratio of the integrated luminosity actually produced to the thoretically producible maximum. It's much lower than the fraction of time that the machine is running, because it includes time for filling, ramping, squeezing, etc; the effect of the luminosity half-...
by adam_jeff
Mon Oct 31, 2011 3:48 pm
Forum: The Accelerator
Topic: Half life sems to have increased from 10 to 12.5 hours
Replies: 1
Views: 1380

Re: Half life sems to have increased from 10 to 12.5 hours

For the last week or so they were experimenting with main-satellite collisions in the two 'low-luminosity' experiments. In other words, instead of colliding two main bunches, they collide a main bunch with one of the very small 'satellite' bunches, that is, a bunch of particles in a supposedly unocc...