Thursday, May 24, 2012

A Picture from Work

I have the greatest job in the world! (While, apart from being the chair of the Math Department, but that's just for another year.) Having tenure at a great up-and-coming liberal arts university, and conducting nuclear physics research at the world's premier medium energy electron accelerator-- which is only a 10 minute drive from our campus! It is darn near a perfect situation.

The accelerator has gone quiet. Data taking has stopped for the next 18 months, after which will turn back on with twice the energy (12 GeV).

Everyone is getting ready. New detectors have to be built and new software written. One of my tasks is to write the event display software for Hall B, one of the four experimental halls: Hall A, Hall B, Hall C and Hall Tim. (Just kidding, Hall D.)

Here is a screen shot from version 0.1:

This shows one set of detectors for our experiment: drift chambers. This is a 2D slice (we also have 3D views) in which you can imagine the tilted 2D rectangles are actually tilted 3D boxes perpendicular to the page. Each box contains six layers of wires, with 112 wires per layer. The wires are also (roughly) perpendicular to the page. The wires are maintained at high voltage (to produce an Electric field) and embedded in a gas. After a collision at the target (roughly the lower left corner) the outgoing reaction particles go flying toward the detectors. Going through the gas they cause ionization, and the ions collect on the wire which then produces an electronic signal. That results in a rough set of locations of the track which, together with the magnetic field (shown as a "thermal" plot in the picture) allows us to determine the momentum (but not, by itself, the identify) of the particles.

What is show is a simulation (from GEANT4) which is why it is so clean (this simulation did not, in this instance, simulate background) and why we know "truth". That is, the particles are colored based on what type they are. In real data, prior to analysis, we wouldn't know one track was a pion, one a muon, etc.


And another:


  1. Yes David, it's fascinating work and I'm proud to have been part of it (helping Dr. K Beard do muon simulations with G4Beamline.) The search for the Higgs was such a media madness, and how curious for the "finding" of this special particle to be so dependent on dry statistical standards of adequate proof. I left a little pastiche at various websites, sometimes appreciated:

    July 4th was a great day for physics! Detective "Higgsy Callahan", AKA "Dirty Higgsy", has been on the trail of this perpicle for years and had a few things to say about the search:

    Making sure the perpicles couldn't get away:

    Higgsy: We're not just going to let you walk out of here.
    Particles: Who's "we", sucker?
    Higgsy: ATLAS, CMS and me.

    As the trail got warmer, he thought it was chancy:

    "I know what you're thinking: "Did we find five sigma, or only four?" Well, to tell you the truth, in all this excitement, I've kinda lost
    track myself. But being this is the LHC, the most powerful collider in the world, and would blow our mind clean off, you've got to ask yourself one question: "Do I feel lucky?" Well do ya, punk?"

    And as he closed in for the "arrest", Dirty Higgsy said:

    "Go ahead, make my day!"

    Well, the Higgs did*! Congratulations to all the theorists, workers; and especially to Dr. Peter Higgs!

    *However, things may be even more interesting, there are hints this isn't the fully expected standard Higgs. Ahh, keep feeling lucky, perps (and Stephen Hawking ...)

  2. Well then, moving on to serious matters so to speak: At How the Higgs Boson Posits a New Story of our Creation, we find the execrable Pharyngulite wanna-be Lawrence Krauss suggesting that the Higgs obviates the need for a creator God. I left the following comment:

    No, this is a fallacious argument: "... creating “stuff” from “no stuff” seems to be no problem at all—everything we see could have emerged as a purposeless quantum burp in space or perhaps a quantum burp of space itself. " A quantum "burp" happens in an previously existing physical manifold, it is not "nothing" - if it was, there'd be no rules or process possibilities already there. The term "nothing" is misleading, it functions grammatically like a noun but is really supposed to be a *logical negation* of anything existing. So "suppose there was nothing" is not postulating a sort of weird empty "something" that anything could come from, it is just a botched wording of "suppose there was not anything in existence" - which already means, a complete and self-contained nullity. This is a basic logical point, it doesn't depend on details of physical properties or theory.

    None of what happens within the scope of the physical laws themselves, *once we already have* such a structure, explains how or why they are a background to other developments instead of there truly "not being anything" as I explained before. Lawrence, distinguished philosopher/physicist David Albert already gave you a spanking over this, very rightly pointing out that of course particles etc. may come from pre-existing quantum fields (and BTW the Higgs is what gives them mass, it doesn't "create" them in any deeper way than the background), but that doesn't explain why such fields exist at all, why they are that way and not otherwise (why for example, not a classical universe, or why not no universe at all (and again, "no" is here being properly used as a logical negation, not as a trick of bungled semantics making it look like a stuff called "nothingness.")

  3. Here's a good description of the Judeo-Christian religion.

    "The word God is for me nothing more than the expression and product of human weaknesses, the Bible a collection of honorable, but still primitive legends which are nevertheless pretty childish. No interpretation, no matter how subtle, can (for me) change this.
    For me the Jewish religion like all other religions is an incarnation of the most childish superstitions. And the Jewish people to whom I gladly belong and with whose mentality I have a deep affinity have no different quality for me than all other people. As far as my experience goes, they are also no better than other human groups, although they are protected from the worst cancers by a lack of power. Otherwise I cannot see anything 'chosen' about them."-Albert Einstein

    Religion is mind rot. A bunch of asinine Stone Age bullshit that only the weak minded, apparently in need of comforting fairy tales, can swallow.

    Virgin births, blood sacrifices, talking donkeys, genocide, infanticide,slave trading, stoning non-virgins to death, stoning homosexuals to death, etc. In other words, absolute Stone Age bullshit!! Gotta love it!!