Experiment
drorzel | September 20, 2007Let's say you have a mirror-- not some cheesey $2 makeup mirror, but a research-grade aluminum mirror-- and it has some crud on it, say a film of junk deposited during your Summer Institute for Hot MEtal Chemistry. Like, say, the mirror on the right in this picture:
How do you get that mirror clean?
Well, first, you assemble your tools:
You'll need the mirror, some lens tissue (special soft, lint-free paper), a hemostat (I prefer the curved-tip kind shown here, but you can use the straight ones, too), and some solvent (the bottle here is methanol, but you sometimes need to use acetone).
The…
drorzel | September 12, 2007In a comment to the book announcement, "HI" makes a request:
Would you be able to summarize the recent paper "Progressive field-state collapse and quantum non-demolition photon counting" (Nature. 2007 Aug 23;448(7156):889-93) for non-specialists? How do you interpret it?
This probably would've slipped by me if not for this comment, but it's a really nice paper, and I'm happy to give it a shot. There's also a commentary by Luis Orozco that you won't be able to read without a subscription because Nature are bastards that way.
The basic idea of this paper is that they prepare a quantum system…
lundblad | September 7, 2007I should probably sneak in a few posts before Chad gets back. It's been a hectic week, as the time came for my current experiment (as it does for all experiments) where one stops futzing around trying to make things better, and takes the actual data, with an eye to moving on. This means that you want good, clean runs with lots of attention to detail (as opposed to the semi-qualitative exploration of parameter space, when you're first seeing an effect), and the first thing life-wise that suffers during this phase is blogging.
But the second-worst blog post in the world is the why haven'…
bergman | September 5, 2007Steinn reports that the NRC has made its recommendations for NASA's Beyond Einstein program. The winners appear to be LISA, a gravity wave observatory, and JDEM, a competition of dark energy focussed satellites. Steinn has lots of links to the various projects. The executive summary of the report is availabe here (pdf).
I know next to nothing about these things, but from afar it always seemed like LISA was one of those neat ideas that was never actually going to happen. The basic idea is to put three satellites in orbit around the sun and bounce lasers around to measure gravitational waves.…
lundblad | August 31, 2007A little while ago, intrepid reporters from the Baltimore Sun dropped by my lab to investigate the newsworthiness of a paper (also on the ArXiv) that had just been published, about which I might talk a little bit before Chad gets back. Surprisingly, the article actually got published, complete with photo and great quotes.
I'm tragically not in the picture, as I was gone that day, but also wasn't an author on the paper; the data were taken last summer, before my arrival, which gives you an idea of the delay in this business between data, writing, and publishing. Highlights from the…
lundblad | August 30, 2007A long time ago, all you needed to think about and record the data you were interested in was a pen and some vellum, and maybe a few candles and a trusty manservant. Somewhere along the line, the chart recorder got invented, and when combined with the oscilloscope and those awful scope cameras, a whole new world of data recording and storage was available. Having one's own ENIAC was pretty helpful, too, especially once manservants (and really, all of bored-noble-of-means science) became gauche.
These days we're a little bit more sophisticated. Computers are indispensable parts of…
lundblad | August 22, 2007Lest this blog turn into a one-trick pony, let me tell you what I did today that's of a little different flavor.
I epoxied some stuff onto some other stuff. More importantly, I calculated a band structure.
This amazes me. Sure, all you squa^Wsolid-state types out there do this every day, over your cereal even, and (in some cases) just have it done for you by the undergrad, but I'm an AMO physicist. I haven't calculated a band structure since I first made sweet love to the Kronig-Penney potential back in the warrens of LeConte and Campbell, guided by the two-who-are-one, Cohen and…
lundblad | August 18, 2007While I'm sure there will be a lot of chatter around here in the next few weeks about the vacuum (or, God help me, vacua), I feel like I should lay the groundwork by talking about laboratory vacuum. I know I'm here to talk about cold atoms and the hot stuff going in in experimental physics right now, but I've spent a lot of time in the last couple days dealing with vacuum, and I want to tell you about it.
If you want to do most sorts of atomic physics experiment, it's essential that you isolate what you're interested in studying (atoms) from stuff that will either knock those atoms away,…
drorzel | August 15, 2007Michael Nielsen, who's so smart it's like he's posting from tomorrow, offers a couple of provocative questions about the perception of a crisis in funding for basic science:
First, how much funding is enough for fundamental research? What criterion should be used to decide how much money is the right amount to spend on fundamental research?
Second, the human race spent a lot lot more on fundamental research in the second half of the twentieth century than it did in the first. It's hard to get a good handle on exactly how much, in part because it depends on what you mean by fundamental…
drorzel | August 10, 2007I'm working on something at the moment that involves talking a bit about the historical development of quantum theory, and specifically the demonstration of the wave nature of electrons. One of the famous proofs of this is the Davisson-Germer experiment, showing that electrons bouncing off a nickel target produce a diffraction pattern.
(As an aside, let me note that I love the fact that the Wikipedia stub on the experiment blatantly plagiarizes the text of the Hyperphysics page (which is screamingly obvious, in that it refers to a figure that they didn't cut-and-paste into Wikipedia). Way to…
drorzel | July 12, 2007Peter Steinberg is lecturing at a summer school in Florida, and has posted the slides for the three lectures he gave about recent work at the Relativistic Heavy Ion Collider on Long Island. The first lecture is linked from that post, and the other two are available (at the moment) from links on the sidebar.
These are gigantic PDF files-- the first one especially, which clocks in at 32.4 MB-- but the first lecture is a very nice introduction to the physics they're exploring at RHIC. I haven't looked at the other two yet, but if they're as good as the first, they'll be worth the long download.
drorzel | June 25, 2007The Large Hadron Collider at CERN has suffered some setbacks in recent months, but they aren't letting that hold them back:
CERN has announced that the Large Hadron Collider will switch on in May 2008, with collisions at full energy starting in summer 2008.
"We'll be starting up for physics in May 2008, as always foreseen, and will commission the machine to full energy in one go," said LHC project leader Lyn Evans.
Of course, they're currently working to repair a magnet that was damaged during a pressure test, so starting on schedule will mean some corners have to be cut. Specifically, they'…
drorzel | June 21, 2007The mysterious saga of "supersolid" helium continues this week. If you recall, there were some new results a little while back showing that the effect depends on disorder in the samples, followed by neutron scattering studies that didn't show the expected distribution of states in the sample. These results suggest that something else is going on in these samples, and the explanation of the observed effects isn't all that simple.
Now, Moses Chan and co-workers at Penn State, who made the initial discovery, have returned with a new paper in which they see "supersolid" behavior in single…
drorzel | June 12, 2007Clifford Johnson is pointing to a pair of stories about extrasolar planets. One is a news piece about the "flood" of new discoveries, and the other is a Top 10 list from space.com (warning: irritating web design).
This provides a good excuse to roll out a blog suggestion from Ron Walsworth, who pointed out a possible connection to the ultra-stable lasers that Jun Ye and Jim Bergquist talked about on the first day of last week's conference. He suggested that, in the future, these ultra-stable lasers may be useful not only for comparing clocks on Earth, but as a crucial reference to help detect…
drorzel | May 24, 2007The Female Science Professor has a nice post about high and low tech data acquisition:
An MS student has repeatedly questioned why he/she has to use a low-tech method to acquire, somewhat tediously, some data that could be acquired more rapidly with a higher-tech method. I say 'more rapidly' because the actual acquisition time once the machine is on and ready for analysis can be fairly rapid, but this technique becomes much less rapid when the substantial (and tedious) preparation time is considered. In any case, with the low-tech method, you can get data any time you want, and the amount of…
drorzel | May 24, 2007A discussion in the back-channel forums reminded me about all the many things I've learned how to do badly in the course of my scientific training. My junior high shop teacher probably sprained something laughing the first time he heard that I was doing machine shop work as part of a research project, but it's part of experimental science, so I know a little bit about how to work a milling machine these days.
It's a crazy busy week for me, and today will be largely taken up by hosting Jennifer Ouellette, who's visiting campus to tell us about the physics of Buffy the Vampire Slayer. So, I've…
drorzel | May 15, 2007There's a big long Dennis Overbye article about the Large Hadron Collider in the Times today. The paginated version runs to seven or eight pages on the web, and Overbye is a good writer, so you can be fairly sure it's exhaustive and detailed and interesting.
I can't say that authoritatively, though, because I got about five paragraphs in, and gave up. I'm officially sick of rapturous articles about the LHC, which isn't going to turn on for several months yet, assuming everything goes smoothly.
Yeah, yeah, it'll address the most fundamental questions in physics, it'll provide an unprecedented…
drorzel | May 11, 2007The bizarre saga of Rusi Taleyarkhan (which I've mentioned before) keeps getting stranger. Previously, Purdue University had announced that it conducted an investigation of Taleyarkhan's work and cleared him of any misconduct, without saying, well, anything much about the investigation. Now, after pressure from Congress on the question, the New York Times reports that they're opening a new investiagation.
The letter from Congress that triggered this contains the first real details of the earlier investigation, including this absolutely boggling couple of paragraphs:
Up to now, Purdue has…
drorzel | May 8, 2007One of the other ScienceBloggers is prone to complaining in the back-channel forums that we don't have enough bloggers who work in some subfield of biology or another-- we need more left-handed shrew ecologists, or some such. This is, of course, patently ridiculous. What we need is a physics blogger from the condensed matter world, so we'd have somebody to explain what's up with "supersolid" helium:
Superfluidity was discovered in the liquid phase in 1938, when Pjotr Kapitsa - who shared the 1978 Nobel prize for the work - found that liquid helium-4 suddenly behaves as if it has zero…
drorzel | April 19, 2007One of the things that I always have to explain toward the end of my laser cooling spiel is that the technique only works well for particular atoms. Somewhere on the high side of twenty different elements have been laser cooled and trapped, but the standard techniques don't generalize well to even simple diatomic molecules, let alone solids.
Given that, you might be surprised to see the headline "Laser Cooling of Coin-sized Objects," referring to this paper in Physical Review Letters. The description sounds really cool:
Now, a collaboration of scientists from the LIGO Laboratory at MIT and…