Search found 76 matches

by photino
Sat Jan 23, 2010 12:44 pm
Forum: Controversial topics
Topic: Several biggest errors of particle physicists.
Replies: 1135
Views: 214748

Re: Several biggest errors of particle physicists.

Wormholes have space-time metrics, which is close to Kaluza-Klein space-time with extra-dimension, uniting gravity and electromagnetism. IF what you mean by this is that you are interpreting a Reissner-Nordstrom metric as a KK system (fair enough), then you are probably misunderstanding the Einstei...
by photino
Fri Jan 22, 2010 11:53 pm
Forum: Controversial topics
Topic: Several biggest errors of particle physicists.
Replies: 1135
Views: 214748

Re: Several biggest errors of particle physicists.

Stephen - sure, beyond a certain point maybe it's a matter of taste which (correct) line of argument one personally finds most convincing, depending on the evidence and theoretical tools used. But I must say I find it astonishing that one could regard the process of black hole *production* (which re...
by photino
Fri Jan 22, 2010 11:27 pm
Forum: Controversial topics
Topic: Several biggest errors of particle physicists.
Replies: 1135
Views: 214748

Re: Several biggest errors of particle physicists.

Stephen, if you don't believe in Hawking radiation, there are other chains of reasoning - for instance based on astrophysical evidence. You can find the papers linked from the following wikipedia page (they are not that hard to read, at least if only you want to get the gist): http://en.wikipedia.or...
by photino
Fri Jan 22, 2010 7:49 pm
Forum: Controversial topics
Topic: Several biggest errors of particle physicists.
Replies: 1135
Views: 214748

Re: Several biggest errors of particle physicists.

March_Hare, even if a mini-BH was at rest it would be no danger because its temperature would be extremely high (for an uncharged black hole, it would be inversely proportional to the mass, and the mass is tiny). It will therefore radiate and lose energy, hence lose mass. This means it gets hotter! ...
by photino
Fri Jan 22, 2010 2:34 pm
Forum: Controversial topics
Topic: Several biggest errors of particle physicists.
Replies: 1135
Views: 214748

Re: Several biggest errors of particle physicists.

Here is the English translation of Fortov's introductory review article: http://www.iop.org/EJ/article/1063-7869/52/6/R08/PHU_52_6_R08.pdf?request-id=c943ce88-3e73-4a7c-8374-15966a961552 I note that in this article, Fortov is very positive about the LHC! The relevant passage Ivan cited is on page 25...
by photino
Fri Jan 22, 2010 10:54 am
Forum: Controversial topics
Topic: Several biggest errors of particle physicists.
Replies: 1135
Views: 214748

Re: Several biggest errors of particle physicists.

That diagram of a "magnetic hole" is bizarre. If you had electrons and positrons on the same orbit, they would annihilate. Quite apart from the question of what is supposed to cause those orbits (and worse, the lattice-like arrangement) in the first place.
by photino
Mon Jan 11, 2010 6:21 pm
Forum: Science
Topic: Can black holes grow?
Replies: 36
Views: 9112

Re: Can black holes grow?

>How do black holes ever grow? >For is it not at the event horizon where time freezes (according to einsteins theory) for >masses speeding up to the velocity of light? Clocktime at the horizon freezes relative to our >clocks. Then, how can black holes ever accumulate mass in the timeperiods our cloc...
by photino
Thu Dec 17, 2009 1:30 pm
Forum: LHCb
Topic: Q&A with a LHCb expert
Replies: 6
Views: 3657

Q&A with a LHCb expert

From the chat... [20:53] <photino> CMS has also rediscovered the pion http://cms.web.cern.ch/cms/Media/Publications/CMStimes/2009/12_14/images/K0s.png [20:53] <photino> lhcb was faster... [20:54] <Anitusar> lhcb also found the Ks and lambda :) [20:54] <photino> sorry that's actually the K_0 producti...
by photino
Tue Dec 15, 2009 12:53 am
Forum: LHCb
Topic: Event Display
Replies: 12
Views: 7583

Re: Event Display

OK, based on the above, a first stab at colour ID's (it's a bit hard to tell due to the lack of resolution around the velo in particular): light purple = TTracks turqoise = downstream dark blue = long tracks grayish light blue = upstream dark purple = RICH photons light green = also TTracks? green =...
by photino
Sun Nov 29, 2009 12:34 pm
Forum: New Users Start Here
Topic: Fascinating Facts about the LHC
Replies: 13
Views: 12801

Re: Fascinating Facts about the LHC

One of my favourite facts: Remember how metal contracts as it gets colder? When the LHC is cooled down, each sector shrinks by about 10 metres in length. This means the entire ring shrinks by 80m! (almost the length of a football field). (This change has to be absorbed - thats why components are joi...
by photino
Sat Nov 28, 2009 1:15 am
Forum: New Users Start Here
Topic: What do the displays mean ?
Replies: 85
Views: 54418

Re: What do the displays mean ?

Neat summary of the basic "LHC operations" sequence: After re-cycling, the machine is ready for injection of 450 GeV protons This should take ~15 minutes The beams are ramped to nominal energy (3.5 TeV in 2010) This takes about ½ hours Beams are prepared for physics: Squeeze to make them smaller at ...
by photino
Sat Nov 28, 2009 12:35 am
Forum: The Accelerator
Topic: What does ... mean?
Replies: 28
Views: 14257

Re: What does ... mean?

This contains a nice explanation of luminosity and intensity... there's lots and lots of detail there.

https://edms.cern.ch/file/445831/5/Vol_1_Chapter_3.pdf

roughly speaking,
intensity = number of particles in a bunch
luminosity = number of particles going through a cm^2 per second
by photino
Thu Nov 26, 2009 3:47 pm
Forum: New Users Start Here
Topic: What do the displays mean ?
Replies: 85
Views: 54418

Re: What do the displays mean ?

Re the BTV displays on page 1: it appears the BTV images are produced by lowering a scintillating screen into the beam. Since this somewhat degrades the beam itself, the screen is only lowered into the beam when measurement is required. I suspect some of the images we are seeing are artifacts of BTV...
by photino
Wed Nov 25, 2009 11:19 pm
Forum: New Users Start Here
Topic: What do the displays mean ?
Replies: 85
Views: 54418

Re: What do the displays mean ?

Or maybe the red bar (like for instance at the moment on the right at BTVST.A4R8.B2) is a beam that is not very collimated? Then the red bar on the left display (BTVST.A4L2.B1) would also be the presently circulating second beam? Ah well, maybe someone from CERN will enlighten us at some point...
by photino
Wed Nov 25, 2009 10:27 pm
Forum: New Users Start Here
Topic: What do the displays mean ?
Replies: 85
Views: 54418

Re: What do the displays mean ?

This site explains the codes above the four images on LHC Page1. They denote the beam TV camera the image is coming from.
http://ab-dep-bi-pm.web.cern.ch/ab-dep- ... ies.BTVLHC

It would be nice to understand better the actual image itself ;)