Experiment
drorzel | March 10, 2008While Kate was off being all lawyerly at her NAAG workshop, I spent my time visiting my old group at NIST, and some colleagues at the University of Maryland. This wasn't just a matter of feeling like I ought to do something work-like while she was workshopping-- I genuinely enjoy touring other people's labs, and hearing about the cool things they're working on.
I figure that, having spent a day and a half talking about hot new physics experiments, I may as well mine them for blog fodder. I've managed to scrounge up papers related to a lot of the experiments in question on the arXiv, but the…
drorzel | March 10, 2008A great many physics experiments need to be conducted at low pressures, in order to avoid sample contamination, thermal effects, or dissipative forces produced by interaction with air. Some experiments don't require all that much in terms of vacuum, while others require pressures so low that they're limited by the diffusion of gasses through stainless steel.
To cover the wide range of pressures needed for different experiments, there are lots of different types of vacuum pumps, and there are nearly as many schemes for classifying them. As an experimental physicist and blogger, though, I've…
drorzel | March 1, 2008As mentioned previously, I was invited to discuss physics and politics at one of the local fraternities earlier this week. Oddly, given the primacy of Greek organizations on campus, this is only the fourth time I've set foot inside a fraternity or sorority house in seven years. The previous occasions were times when I was doing housing inspections for the committee that handles those matters.
They've cleaned up the house since the other time I was there-- they used to be Φ Γ Δ, years ago, and then there was a brief interregnum when they were officially "Alpha Beta" (referred to as "oh, those…
drorzel | February 29, 2008I spent the bulk of yesterday afternoon doing vacuum system work, specifically working on the system to feed gas into the atomic beam source. My feelings about this can be inferred from the Facebook status message I set at the time: "Chad Orzel abhors a vacuum."
The apparatus I'm building uses laser cooling to decelerate an atomic beam of krypton atoms in a particular metastable state. This works brilliantly to slow metastable krypton atoms down, but the only atoms affected by the laser are krypton atoms-- everything else continues along unimpeded. As a result, the entire experiment needs to…
drorzel | February 13, 2008I'm not hugely enthusiastic about the ResearchBlogging.org project, but it's a little ridiculous that they've been active for weeks now, and there still isn't a single post in the "Physics" category. If they're going to offer the category link, something ought to come up when you click it, so let's give them some blogging on peer reviewed physics research.
The recent paper that most seems to lend itself to a quick explanation is this Phys. Rev. Letter from the Katori group at the University of Tokyo on the trapping of neutral mercury atoms. Full disclosure: Dr. Katori was a student of Prof.…
drorzel | January 11, 2008It's been a while since I did one of these (see "How to Tell a True Lab Story" for an explanation), but yesterday's laser tech story reminded me of one.
The lab next to mine in grad school also used an argon ion laser to pump another laser, but they were much more cramped for table space than we were. Instead of putting the argon ion laser (which was about 6' long) on top of the table, they put it on a bench that slid under the optical table, then used mirrors to direct the beam up onto the table top. Since the ion laser is pretty much a black box, this worked great, and they could drag it…
drorzel | December 18, 2007I could probably tease this information out of the Particle Data Group website, given enough time, but somebody with a background in particle physics can probably answer this in two seconds, so I appeal to the Internets:
What is the shortest lifetime of a particle that has been directly detected?
By "directly detected" I mean, well, directly detected. Something that has been identified from a track in a detector, or a click in a calorimeter, and not something whose existence has been inferred from a resonance observed in the production of other things.
My half-assed guess would be a neutral…
drorzel | December 11, 2007Faith in theory and curve-fitting, at least...
Tommaso Dorigo reports some new results, which are based on a figure that could be titled "Why I Am Not a Particle Physicist #729":
"What's the problem?," you ask, "There's a nice big peak there, looking a little like a black-body spectrum."
Ah, but that's not the signal. The green shaded region in the big plot is all background. The signal is in the tiny little gap between the green background line and the blue data points on the right-hand side of the enormous background peak.
Now, this is actually a pretty solid result, as you can see from…
drorzel | December 3, 2007I burned out some diode lasers a while back, and needed to buy replacements. Here's one of the replacements on top of the tube containing the other, with a US quarter for scale:
Here they are, with the box and packing material used to ship them to me:
I realize that this is probably due to somebody at the laser company deciding to save money by standardizing on a single size of shipping container. Still, this seems just a tiny bit excessive...
drorzel | November 21, 2007I generally like Gregg Easterbrook's writing about football (though he's kind of gone off the deep end regarding the Patriots this year), but everything else he turns his hand to is a disaster. In particular, he tends to pad his columns out with references to science and technology issues. I'm not quite sure what the point of these is supposed to be, other than to demonstrate that he, Gregg Easterbrook, is so much smarter than the average football fan that he knows, like, rocket science and stuff. The problem with that is that his knowledge of rocket science seems to owe more to Star Trek…
drorzel | November 13, 2007 Jennifer Ouellette meantions it as the jumping-off point for her particle-wave duality post, but I want to spend a little time talking about this paper on single-electron interference (Science 318, 949 (2007)), because it's a very nice piece of work. There's also a Physics World news article about the experiment, which is pretty good, but slightly understates the coolness of the experiment.
The experiment here is extremely simple: They take a jet of molecular hydrogen, and hit it with extremely high-energy photons from the Advanced Light Source at Lawrence Berkeley National Lab. These…
drorzel | November 9, 2007 I have a bunch of science news sources in my RSS feeds, and every evening, I scan through the accumulated articles to try to figure out what physics-related stories there are to talk about. Sometimes, it's hard to find anything, but other days, you get stories that lead to four press releases at EurekAlert (one, two, three, four), a write-up at Backreaction, a Physics World news story, and a Dennis Overbye piece in the New York Times. I guess I really ought to say something about the new results from the Pierre Auger Observatory, published this week in Science (Science 318, 938 (2007), if…
drorzel | November 8, 2007There are a lot of high-tech tools that are absolutely essential to the functioning of my lab. The diode lasers I use are a couple hundred bucks each, and only available from a handful of companies. I've got a couple of digital oscilloscopes that are really impressive instruments, packing a huge amount of signal-processing power into a single smallish box. I have an infrared viewer that I use to see the beam, and the lab is literally just about shut down when a colleague needs to borrow it.
Something that people outside of experimental physics don't really appreciate, though, is that there…
drorzel | November 5, 2007I'm suffering muscle twinges in my neck and shoulder that are usually linked to excessive typing. As I have a grant proposal to review, a senior thesis to help whip into shape, and a book under contract, this means that blogging will be substantially reduced while I ration my typing to those things that pay the bills. You'll get more linking and less thinking, at least until my shoulder calms down a bit.
I don't want to pass up a set of links-- two press releases and a news story-- on some new results regarding friction:
If you want to reduce the friction between tiny objects, just increase…
drorzel | October 16, 2007OK, the monkey business may have been a little too abstract for a good audience participation entry. So let's fall back on a classic:
What science-related superpower would you most like to have?
Because this is a Dorky Poll, "science-related superpower" here means a supernatural ability that is useful for doing science. Because battling crime is passé.
Personally, I think I'd have to go with the ability to manipulate small objects remotely. I'm a big guy, and I have big hands, and you know what they say about big guys with big hands...
That's right, they have a lot of trouble turning screws…
drorzel | October 9, 2007Having gotten that silly Medicine business out of the way, the Swedish Academy has moved on to the important Award, with the 2007 Nobel Prize in Physics going to Albert Fert and Peter Grunberg for the discovery of Giant Magnetoresistance. This is one that people have been calling for for a while, now.
I'll try to give a more complete explanation of what this is and why it's important later, but I'm going to Boston with a student group today, and I need to run to catch the bus. I'll just note quickly that this should be applauded by blog readers, because GMR is an enabling technology for…
drorzel | October 2, 2007Speaking of cryptic particle physcis results, noted rumor-monger Tommaso Dorigo has a rather long post about the ongoing Higgs search. It basically boils down to "There are new results due to be released soon, and I'm not going to talk about them," which wouldn't seem to require 2000 words, but there you go.
Anyway, if you're anxiously following the search for the Higgs boson, he's hinting away about the upcoming update to the small signal that created a bit of a stir back in January. If there's anything to it, that would be really exciting, but for now, only people within CDF know, and they'…
drorzel | October 2, 2007I've got a bunch of EurekAlert feeds in my RSS subscriptions, that I use to keep up with recent developments, because I need blog fodder. One of the really striking things about these is how extremely variable the quality of the releases is.
Take, for example, the release headlined New particles get a mass boost, describing results from extremely precise measurements at Jefferson Lab:
A sophisticated, new analysis has revealed that the next frontier in particle physics is farther away than once thought. New forms of matter not predicted by the Standard Model of particle physics are most…
drorzel | September 28, 2007Physics World had a news story about developments in quantum computation, covering two new papers in Nature:
Coupling superconducting qubits via a cavity bus from the groups of Steve Girvin and Rob Schoelkopf at Yale, also described in this press release.
Coherent quantum state storage and transfer between two phase qubits via a resonant cavity by a group at NIST at Boulder, also described in this press release.
These are completely independent experiments, as far as I know, but they're doing essentially the same thing: They're demonstrated the transfer of quantum information between two "…
drorzel | September 26, 2007So, I've put myself into a position where I need to spend a substantial amount of time thinking about weird foundational issues in quantum mechanics. This has revealed to me just why it is that not that many people spend a substantial amount of time thinking about weird foundational issues in quantum mechanics.
Let's consider a Mach-Zehnder interferometer, of the type shown in the figure at left (click the figure to see the original source). A photon (or an electron, or an atom, or any quantum particle) enters the interferometer at the lower left, and is split onto two paths by a 50-50…