Live web cast of dragon/black hole in EU - Page 7

The image is produced by an event display program, which provides a nice visual representation of the output of the whole detector (ATLAS in this case) for one event. One event here means one beam crossing, generally, which could include up to several proton-proton collisions, but generally only one interesting one.

Now, I'm not completely familiar with ATLAS (I'm a CDF guy), but I'm pretty sure the top left section is the muon chambers. These record, well, muons, which are the only thing which interacts poorly enough to consistently punch all the way through the detector and the layers of steel in front of the muon chambers, but strongly enough to be recorded all the way along its passage.

The top center shows a zoomed in view of the middle of the top left: the calorimeters. Calorimeters record the amount of energy that enters them, and are arranged radially, so that you can see just how much energy (in the form of both mass and kinetic energy) was carried away from the collision in a particular direction. This is accomplished by means of scintillator crystals, which tend to get ionized by the passage of high energy particles, thus absorbing some energy from the particles, and then they reemit that energy as photons, which are collected and measured in photomultiplier tubes. The calorimeters are used to look for most particles, particularly electrons and "jets" (which are a spray of particles resulting from the ejection of a quark from the collision), both of which leave clusters of energy over a significant area of the calorimeter.

The top right is again a zoomed in view of the middle of the top center: the tracking chambers. These act sort of like thousands and thousands of geiger counters; every time a charged particle passes through the vicinity of a wire in the tracking chamber, it records a hit. You can then piece all these hits together in a line to measure the track of a particle. The offcenter pink and blue line is almost certainly a cosmic ray, which will naturally leave a track in the chamber, but not appear to originate from the interaction point. In the lower left, you can see what is probably two different short track segments.

The first three images have been more or less slices out of the center of the detector, perpendicular to the beam line. The lower left is a side-on view, showing the somewhat less important parts of the detector that lie at small angles to the beam line, the so-called forward detectors.

The lower right is probably intended to be a flat plot of the calorimeter, as if you sliced it parallel to the beam line and unrolled it. The height of the bars would then indicate how much energy was deposited in each section. However, at the moment, that plot looks like it is having some sort of overflow problems.

On September 10 2008 20:19 betaben wrote:
http://atlas.web.cern.ch/Atlas/GROUPS/OPERATIONS/prodSys/atlasoracleadmin/10Sep2008/beam/index.php
http://picasaweb.google.com/graeme.a.stewart/LHCRedButtonDay#

looks like they sprayed the detector a bit - that can't be too good.

On September 13 2008 02:20 betaben wrote:


this, and more pictures, are here

On November 19 2009 01:31 zatic wrote:
This thing is just as bad as SC2. I predict there will be another delay, pushing the thing back to December 2012.

On November 19 2009 01:31 zatic wrote:
This thing is just as bad as SC2. I predict there will be another delay, pushing the thing back to December 2012.

On November 18 2009 22:05 meeple wrote:
Did anyone hear about the bird that somehow damaged it?

http://www.time.com/time/health/article/0,8599,1937370,00.html

On November 18 2009 21:56 disciple wrote:
More than a year after an explosion of sparks, soot and frigid helium shut it down, the world’s biggest and most expensive physics experiment, known as the Large Hadron Collider, is poised to start up again. LHC has been fixed and seem ready to become operational by the end of this week.

Various sources however claim that the Collider wont be started again before December. But will it actually work? A pair of otherwise distinguished physicists have suggested that the hypothesized Higgs boson, which physicists hope to produce with the collider, might be so abhorrent to nature that its creation would ripple backward through time and stop the collider before it could make one, like a time traveler who goes back in time to kill his grandfather.

Wow.

On November 19 2009 04:14 Foucault wrote:


The funny thing is that reality is more crazy than science fiction. What you mentioned above doesn't sound impossible at all, try quantom physics for unexplainable and extremely weird stuff.

We are quite blind about the weirdness of reality, in our daily lives.