Christopher M: There are several books on the experimental side of high-energy physics, from technical books,
to general textbooks, to popular accounts written by particle experimentalists. Some examples are: (general
textbooks) _Detectors for Particle Radiation_ by K. Kleinknecht, _Experimental Techniques in High Energy
Physics_ by T. Ferbel, and the excellent chapter in the classic _Introduction to High Energy Physics_ by D.
Perkins. Physicists who already know the topic look things up at
http://pdg.lbl.gov/2008/reviews/pardetrpp.pdf . Popular accounts include L. Lederman’s horribly-titled _The
God Particle_, and _The Rise of the Standard Model_ by L. Hoddeson et al., amongst many others. As for the
precision of the detectors, that is indeed very carefully measured and calibrated using a variety of means –
primarily tracks of particles themselves. As for alignment, the typical scale that experiments need to
calibrate the position of the innermost detector elements to is O(20 microns) or so for the very innermost
pixels. The further out in the detector you go, the less sensitive we need to be. Now how, you may ask, do
we use the very same particle tracks we are measuring to calibrate the detector? The answer is that the vast
majority of events don’t get used for physics, so these aren’t typically the same events. But one thing you
can be reasonably sure of with almost any particle track: _it doesn’t zigzag_. Particles travel in a smooth
curve: in a constant magnetic field as within a detector, their tracks always form a helix. So if you see
that the tracks your particles are making are zigzagging, and always in the same way when they cross a
certain detector element, it is likely that you have the position of that element wrong. This is the
technique by which the detector is aligned. We write computer programs to take a bunch of test events from
the detector, determine zigzag patters, and thus determine an alignment pattern for the detector to remove
them. We can align using tracks from cosmic rays or real beam tracks. A lot of effort is put into designing
the detector elements such that they don’t vibrate, so we don’t need to do too much for effects that are
rapidly time-dependent in-between accesses of the detector (but there are some other techniques for those, in
fact ATLAS also uses a laser interferometry alignment system to check those types of movements, but they tend
to be small). Hope that answers your question, ask if you have more.

collin237: Particles almost never stop when they hit a pixel detector — they pass through the layers of
pixels, as well as the outer tracking elements, and we detect a track if the particle is charged. How does
one display particle tracks in 3-dimensional space, especially on a flat computer screen? This is a
challenge, similar to many computer 3-D graphics challenges. Typically event displays allow one to rotate
one’s view of the event and see it from different angles. There are many recent developments in computer
graphics that may allow this to be improved in the future, see e.g.
http://gordonwatts.wordpress.com/2008/06/25/head-tracking-and-3d-displays-the-new-event-display/

Sili: With the current LHC magnets, there is no way that antiprotons could be used — the antiprotons would
bend in the wrong direction and hit the wall of the beam pipe immediately. Certainly one could conceive of
an entirely new accelerator in the ring that could be p-pbar rather than p-p. But, upgrade-wise, under the
hopefully quite safe assumption that the present LHC is successful, the focus is more on a luminosity upgrade
of the present collider (in 7-8 years or so), and then probably later on (in 15-20 years or so) an energy
upgrade, rather than changing it to p-pbar. We think we can get more physics reach by moving in those
directions (luminosity and energy) rather than pushing hard on antiproton production and storage and
switching to p-pbar — it would be hard to envision as significant gains in, say, Higgs or supersymmetry
cross-sections by moving to p-pbar as by increasing the luminosity and (later on) the energy.

Richard: As for the boxes that detectors are put in for shipping, I’m not sure where you can find a good set
of pictures, maybe others can help. But there is a huge set of pictures and videos in
http://multimedia-gallery.web.cern.ch/multimedia-gallery/

If we put on out prognosticatory goggles and look twenty years into the future, will it possible to run anti-protons through the same pipes? Assuming of course that through the power of Science(tm), we’ll have found away to produce enough of them to get the necessary luminousity.

Actually it may not be a bad thing for the detector, the detector probably will think he finds the biggest particle in the world

(Note: Juan Collar’s recent comments on CV are mentioned.)

(Actually, I could ask the same thing about just an ordinary cloud chamber.)