My Lab
drorzel | August 21, 2008I announced my intention to do some research blogging a little while ago, and managed one pair of posts before the arrival of SteelyKid kind of distracted me. I'm still planning to complete the Metastable Xenon Project blog, though (despite the utter lack of response to the first two), and the second real paper I was an author on is "Suppression and Enhancement of Collisions in Optical Lattices," a PRL from 1998, with a preprint version available here.
So, this is another paper about collisions, obviously, but what's an optical lattice? An optical lattice is an arrangement of laser beams--…
drorzel | March 25, 2008Here's a picture of the gas-handling line leading to the discharge region seen in the plasma post:
How many valves can you count in that picture? If you said "seven," give yourself a pat on the back. Here's the same picture with the valves numbered for your convenience:
("Seven! Seven valves! Ha ha ha ha ha ha ha!!! thunder, lightning)
So why all the hardware?
Well, the gas bottle contains krypton gas at a pressure of several atmospheres. The discharge tube feeds into a vacuum system at 10-7 torr, thanks to some honkin' big pumps. We'd like both of them to stay that way, so some valves are…
drorzel | March 24, 2008A couple more pretty pictures of the apparatus, to pass the time:
This is the plasma discharge source that we use to make metastable atoms. We excite the gas using a RF coil (under the tinfoil) with a couple of watts of power at 145 MHz (local ham radio people must love me...), which creates a discharge in the glass tube. Some small fraction of the atoms are excited to the state that we want in the chaos of the plasma, and we work with those downstream.
When it's working right, there's a pretty steep pressure drop across the discharge region:
The pressure is much lower on the left (there's…
drorzel | March 24, 2008Behold, the end of the world is at hand!
They said I was mad-- mad!-- but now they'll pay...
Well, ok, it's not actually a doomsday weapon. It's a shot of the main experiment chamber in my lab, taken in very low light in an attempt to capture the orange glow of the ion gauge inside the chamber. It only looks like an instrument of apocalypse.
Here's a better lit picture:
And here's one showing a bit of the atomic beam line behind the chamber:
The large copper coils in the foreground are for the magneto-optical trap, while the longer coil stretching off to the right is the Zeeman slower. The…
drorzel | March 11, 2008In the previous post on this topic, I discussed the various types of noisy vacuum pumps, both clean and dirty varieties. This time out, we'll deal with the quiet pumps, the ones that don't deafen people working in the lab.
Quiet and Dirty: The quintessential quiet and dirty pump is an oil diffusion pump. These have no moving parts, but operate by heating a low-vapor-pressure oil inside a series of baffles so that it sprays out in a downward jet. The oil jet will collide with air molecules in the way, and force them back into the reservoir region of the pump, where they can be pumped away by…
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 | 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 | January 17, 2008They're renovating a lab down the hall from mine (this is what led to the power shutdown that temporarily disabled my wavemeter). Today's agenda apparently involves a lot of drilling. Or, possibly, a bank robbery.
Whatever's going on, the intermittent violent shaking of the floor is not so conducive to research with laser diodes. When the boys clean out the bank safe, I hope they make off with quite a haul. I'm going to lunch before anybody gets stabbed.
drorzel | January 16, 2008Last week, I made an oblique mention of an equipment failure, and commented about the positive experience I had in dealing with their engineers on the phone. I carefully avoided naming the broken product or the company I was dealing with, out of some obscure sense of blogging ethics.
I shipped the broken item off to them, and on Friday got an email telling me it was fixed:
Don't ask me what exactly we did; but after some alignment and
power-on-power-off, it seemed to come online and give proper readings.
Perhaps the power surge mentioned in your blog hung up some logic gates?
I did a double-…
drorzel | January 8, 2008Having made a snide comment or two about engineers earlier, I feel like I should relate a positive experience today:
Over the Christmas break, there was a power outage in my lab. Not an accidental outage, but a planned outage that nobody told me about-- a contractor cut the breakers in order to do some work down the hall. After the outage, a piece of laser diagnostic equipment wasn't working. After exhausting the really sketchy information in the manual about the particular failure mode of this device, I tried to call the manufacturer. Of course, the original company got bought by a different…
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 30, 2007Via Kate, a story from a legal blog about a decisions in the case of a messy professor:
"Clean your room or get out!" Words from a frustrated parent to a messy teenager? Not quite. The mess-maker in this case was a chemistry professor at the University of Texas, who ignored repeated warnings to clean up his dangerously cluttered lab space. When University officials decided to clean it themselves, the professor caused such a disturbance that campus police had to lead him away in handcuffs. The professor was eventually fired, which prompted a lawsuit claiming that the University retaliated…
drorzel | November 28, 2007Today's lesson:
Lead bricks are really heavy.
That is all. Carry on.
(I had a student working on a project involving radiation over the summer, in a shared lab space. A colleague needs to use the space next term, so I was moving the summer project stuff across the hall to a more permanent home. I got a hand cart to move the lead bricks, stacked a whole bunch of them up, and then had to un-stack most of them in order to move the cart...)
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 | October 17, 2007My least favorite part of academic research has to be waiting for vendors who aren't actually going to call me back. Even when it's a company I've done a lot of business with, "a lot of business" by my standards is peanuts to them, so I'm way, way down the priority queue when it comes to callbacks.
In order to really get anything done, I need to call the vendor, and get an actual human on the line. Leaving voice mail messages really doesn't do any good. And yet, I feel like an asshole calling them every hour on the hour trying to get through to the one person in the company who knows where…
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 | July 6, 2007"Ahhhh... summer at last. No more classes. No more committee meetings. Do you realize what this means?"
"Ummmmm.... no. What does it mean? What are we going to do this summer, Brain?"
"The same thing we do every summer.... Try to do PUBLISHABLE RESEARCH!!!"
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"Are you pondering what I'm pondering?"
"I think so, Brain, but diffusion pump oil is all stinky and viscous, and won't the chickens get upset?"
"You are the very quantum of imbecility, Pinky."
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"The first step in our plan is to use a grating-locked diode laser to-- yes, Pinky?"
"Um, Brain?"
"Professor Brain."
"Um…
drorzel | June 27, 2007It's been ages since I posted a True Lab Story, mostly because I've been too busy to do anything really dumb. I had a good day for True Lab Stories yesterday, though, so here's a tale of something idiotic I did, or, rather, had my students do.
I have a student working on a project to put anti-reflection coatings on some diode lasers, which will help improve their performance in various ways that don't really matter here. This requires the deposition of a very even layer of material that's a couple hundred nanometers thick, which we do using a vacuum evaporator. This consists of a bell jar…
drorzel | June 22, 2007Here's my achievement for the week:
OK, that may not seem like much, but this is what it looked like before I started:
OK, that's not really my only accomplishment for the week-- I have three students for the first half of the summer (two of them for the whole summer), and all three got off to good starts on their summer projects this week. That's why it's taken me a whole week to clean my office-- I've been run ragged getting them all going, and keeping on top of their progress.
Still, the important papers have been filed, the unimportant ones recycled, and the trash taken away. Time to…
drorzel | May 24, 2007Somewhere between yesterday's posts about uselesss junk and useful antiques, there's this. The picture to the right is a tragedy in progress, though is might not look that way: It's an FTIR spectrometer left behind by the previous occupant of my lab.
It's a top-of-the-line instrument, a Bomem DA-8 spectrophotometer, and a new one will set you back better than $100,000. It's no use to me, though, as it's designed to make measurements of spectra in the far infrared-- wavelengths of a couple of microns or more, well past the 800 nm sort of range where I work. So it sits there in the lab, next to…