Posted on July 16th, 2010 1 comment
So I’ve been in Lincoln at the University of Nebraska for about a month now doing research with their Summer Research Program, and I’ve been seriously slacking in the department of documenting my time here…oops. Hope you can forgive me.
Anyway, I guess the place to start would be the program. There are about 60 students from all over the country here with me working with professors on research projects in various disciplines, from Virology to Biomed Engineering to Laser and Optical Physics (me!) and several others. There are 8 of us in the Physics program, and probably about 30 total working on physics-related things (materials research, engineering, etc).
They’re housing all of us on a couple floors of one of the residence halls on campus and feeding us in the dining hall downstairs. All in all, the housing and food isn’t bad, considering it’s free. In fact, I’d say the cafeteria is a bit better than Sodexo back at Truman most of the time. The other people in the program are generally enjoyable too. It’s great to get to meet a lot of people from all over the place–my roommate is from Puerto Rico, the guys across the hall are from Minnesota and Texas, there are a couple people from California, and one or two from New York. There’s also a pretty big range of academic backgrounds: guys from Cornell and Princeton, and several from smaller schools like Truman; we have a girl who just finished her freshman year and, I think, more than one person who will be a 5th year.
As for my project, I’m working on some theoretical stuff–modeling the evolution of a plasma after a very short (femtosecond) laser burst is shot into it. Basically what happens is that the laser pulse pushes the electrons out of the way, and then they rush back in and create oscillations a bit like a wake behind a boat in a lake. Since the electrons are either pushed out of the way, or squished together, they create net electric fields which also oscillate in the wake of the laser. Since this wake is moving at almost the speed of the laser (very near the speed of light), the electric fields can be used to accelerate other particles, such as electrons or positrons that have been injected into the wake, to GeV levels with only a few cm of plasma! Specifically, I’m working with a computer program written in C++ that does 2D simulations of the EM fields along with the density and momentum in each direction. In the previous version, the code set up the plasma with no initial internal energy, a “Cold Fluid Model.” My job is to add in the requisite equations and functions to make the code a “Warm Fluid Model.” So far, I’ve pretty much gotten all the changes made; now it’s just a matter of testing to make sure the numbers it’s giving us are correct. I’ve added in a few diagnostics and so far everything’s looking good.
Aside from the research, we have a lot of fun here. The program has sponsored several fun events: canoe trips, picnics, a sailing trip; and we have a lot of fun individually too. Our evenings are pretty free, so we play sand volleyball usually 2 or 3 times a week, watch movies, find things to do in downtown Lincoln, and just hang out in general. With so many people in a program like this, you’re pretty much guaranteed to find some people you like and there’s almost always something going on if you’re willing to jump in on it. For the record…several people I know of (including myself) do also spend some time studying for the GRE this fall, and we’ve all had our nights of working until midnight–it’s not all fun and games.
Anyway, I think I’ve written enough for now. Thanks if you’ve stuck with me this far. Check back soon for another installment. Ciao!
Posted on July 14th, 2010 No comments
I wish I had more time with this project. It’s all coming together now. I optimistically think I can have a “final product” probe early next week. I’ll make many of them, and then the grad student I’m working with and I will do some measurements to see if they’re as good as the simulations would have us believe. Basically, we just need to compare the performance of a stock probe to the modified probe in action and see what happens!
I’m kind of jumping the gun with this blog post, as you can see. This week, I’ve been experimenting with techniques. My laptop’s background is currently an SEM image of a nearly-finished probe, an image I have drawn so many times and wondered if I could ever build.
We have a final fabrication process down for the coatings, and a batch will finish this weekend. I won’t be there for the final coating over the weekend because I’m visiting a friend from my REU last summer at Yale. I plan to hit the ground running on Monday. Hope for high yields!
Posted on July 9th, 2010 No comments
Well, it’s been a month, and things have developed quite a bit here at Harvard! I can’t believe it’s already been five weeks. At this point, I really only have three more weeks to get all the results I can before I need to make a paper, presentation, and poster–and get ready to fly to Minnesota for the “NNIN Convocation” (for the exceptionally curious: http://www.nano.umn.edu/nninreuconvocation2010/) on August 11.
There were several hoops to jump through to get all the training I needed, but I’ve finished that part now. I was trained on and can work independently on:
- Wet benches in the clean room
- Chemical vapor deposition
- Reactive ion etch
- Spectroscopic ellipsometer
- Thermal evaporator
- Scanning electron microscope
- Focused ion beam
- Atomic force microscope
As I was going through all the necessary training, my mentor (a grad student at Harvard) walked me through the details of the fabrication process. For the last roughly 2.5 weeks, he was out of the country on vacation, so I worked independently.
The focused ion beam is awesome. What I’m dealing with is an SEM that has another column poking down at the sample, 54 degrees from the vertical. Instead of shooting accelerated electrons like the SEM, it shoots accelerated Gallium ions. It can be used for imaging like an SEM (though the ions are much more abrasive to the sample).
Rest assured that this is singularly awesome.
Posted on June 27th, 2010 No comments
Alright, I’ve been here in Davis, California for about a week, so I figured it was about time for a blog post.
So, getting introductions out of the way first – I’m Miguel Fernandez; I’m a Physics/Math double major, and I’ve just finished my second year. After applying to several REUs, I got in here at UC Davis. Protip for underclassmen: Apply early, spots can fill up really fast (after all, there’s tons of competent people out there!).
I got in last Wednesday, after an unpleasantly long flight delay, and I started working the very next day. The project is in granular materials – we have a rotating drum filled with small ball bearings. Some of them are welded into pairs (dimers), and some are welded into sevens (hexes – the seventh ball is the central ball). Video is taken over hours as the drum slowly rotates, and we extract just the frames before and after an avalanche. The idea is to get some information about what kind of circumstances cause an avalanche.
I’ve said “we” so far, but I haven’t done any of that work yet. This has been an ongoing project, and my job, so far, has been to fix code written by previous students. Given that the code is poorly documented, and my personal ineptitude with computer programming (Protip to self: Take more computer science…), it’s taken some time – especially since I’ve had to learn some IDL on the fly. The computer is also less than stellar – some really old (I’d say, 2002) Unix computer. Since IDL is tied up in this computer, and buying the software costs somewhere in the thousands, this has been my workstation. On the other hand, I’ve been looking for an excuse to use a Linux/Unix based computer, and here it is. It’s been quite a learning experience, especially writing/fixing non-trivial programs.
As for the living situation, I’m staying at the dorms (room and board all paid for), which, at least this particular dorm, I’m pretty sure used to be an old motel/hotel. There’s a freaking pool in the middle of the place. It’s awesome.
We’re 14 students working under the REU program here. We’ve all been packed into about 3 dorms rooms, which are suite-style. It’s three rooms per suite, 2 beds per room. As far as the city goes, a little exploration has yielded a great frozen yogurt place (Yolo Berry!), an adult playground (right behind the dorms!!), and a large concrete slide. We’ve also done some fine dining at a local Nepalese restaurant. I wish I could tell you what I ate, but I arrived late, and we all just picked food off of each others’ plates anyways.
We’re about 30 minutes away from the Physics building via walking, about ~13 minutes via bicycle (very kindly provided by the professor in charge of the REU). Speaking of such, pretty much everyone bikes in Davis. It’s a pretty bike-friendly city, so if you like biking, give the place some thought for grad school.
There’s also plenty of fields trips planned (six, if I recall correctly). Just yesterday, we all headed out to San Francisco to visit the Exploratorium. The Exploratorium is basically an awesome interactive science museum. It’s absolutely fantastic, and there is an interesting dynamic when you have a bunch of physics students talking about the science behind the displays (ranging from the purely mathematical like Voronoi Diagrams, optics, acoustics, electricity and magnetism and more). The most fun was probably playing with magnets.
After lunch, we headed to Muir Beach, in the way going across the Golden Gate Bridge. The Pacific is one cold ocean, so we mostly walked along the shore. After finding an old, large (~1m diameter) piece of rope, as well as a trail into small thicket, we settled into a game of Rock, in which we throw rocks at a target (a stick embedded in the sand), hoping to knock it down. This lasted about 30 (great) minutes, until we realized we had a frisbee. Shortly afterwards, we packed up and headed for a hike at Muir Woods, a national park chock-full of redwood trees. My lack of camera was made up by the modest pictures my cellphone took; I might post pictures later.
We wrapped up the day by heading to Muir Beach Overlook, having a beautiful view of the Pacific, and eating the dinner made by the professor. Exhausted, we arrived late at night, and most of us went straight to bed.
It’s been a good week here at Davis. With some luck, I’ll also have the programs fully running by middle of the week, and maybe take some new data myself by the end of the week. Tune in again soon!
Posted on June 9th, 2010 No comments
I’m doing an REU at Harvard University this summer, funded by the National Nanotechnology Infrastructure Network (NNIN) REU Program. I was running a 2-hour simulation, drinking some tea, and reading The Feynman Lectures on Physics when I decided, at Miguel’s suggestion, to give the blog a post.
Let me start with a discussion of general living circumstances. After over three weeks of lazing around Springfield, and also reading some physics articles and researching graduate programs, I jetted over to Boston on Sunday and found my way to my dorm at Harvard in a rather dangerous taxi ride. There was a simple check-in process, and while there was a slight hurdle finding my room that involved some major condescension from a security guard, I eventually found my way to my room to unpack.
The room setup is quite different from any dorm I’ve experienced (this description is essentially superfluous): from the main hallway (where some 60 summer interns in various programs, mostly research-oriented, live), you enter a suite and find a large (perhaps 20′x20′), empty room with a red phone on the ground. Off to the side, there is a narrow staircase, either up or down (mine goes down), which leads to a miniature hallway with several doors: three locked doors marked A, B-D, E-F (or something like that); two doors marked EXIT, one of which actually leads to a bathroom which is shared with the adjacent suite; and a door to a small, empty, triangular room. Inside the E-F door, there is a short hallway with space for hanging clothes and a mirror which connects to two non-lockable doors to individual bedrooms. Having a single room is nice, though it is quite small (perhaps 8.5′x8.5′). The bathroom is efficiently laid out and has two showers, two toilets, and three sinks. Most of the summer residents in research-type programs have gotten to know each other somewhat by hanging out in the common lounge on the first floor, which is fortunate. We’ve gone out to eat a lot, in fragmented groups, which is good for socializing purposes but not sustainable for the whole summer. There’s a kitchen, but I need to get my suite rolling on renting a microfridge, and I need to find a good place to shop (I regretfully feel that a Walmart would be quite convenient right now)–thankfully, there’s a small Trader Joe’s a mile south of where we are, so I’ll check that out soon.
We all met on Monday morning for some orientation sorts of things that lasted through lunch, and on Tuesday morning, we had some safety training that lasted through lunch. Those afternoons, and all day today, I have been hanging out in the lab area being paid to think, which is awesome.
The research I’m doing is strictly speaking in “Applied Physics,” and it is a bit of an engineering challenge.
I can’t do much meaningful experimental work until I have full access to the clean room. There’s a giant, super-high-tech (well, the computers all run Windows XP), absurdly well-stocked lab in there, and my work is sensitive to things like dust. But the graduate student I’m working with has gone through the fabrication techniques with me and also has shown me the focused ion beam (FIB) , and I’ve done plenty of technical reading on the broad subject, so I’m well prepared for when I finish the training for all the equipment I need (hopefully by next week). Additionally, the work I did at the REU at SIUC last summer on nanowires is going to prove quite useful–many of the techniques transfer very nicely.
We’ll see what the future has in store. I don’t know how often I’ll get around to writing on here, but I will try to do better than I did last year. I know this ran rather long, but I don’t exactly have an editor over my shoulder, here. Thanks for checking it out!
Posted on July 29th, 2009 No comments
So I think it’s time somebody posted to the physics blog…where has everyone been all July?
I am currently 6 weeks into my REU, with 4 more to go. Up to now I’ve been working on assembling and testing a voltage controlled oscillator (VCO). The VCO is part of the laser frequency stabilization control loop here at LIGO. The interferometer requires a very stable laser beam because fluctuations in the laser’s frequency that is input to the interferometer are indistinguishable from a change in the lengths of the interferometer arms (the thing we’re trying to measure). The laser that we currently use is far too noisy out of the box. (Laser noise by-the-way comes from things like electrical jitter in power supplies and control circuits, thermal noise acting on the laser cavity, and the optical pumping that makes the laser lase). To correct for noise, we take the beam before it is injected into the main interferometer and pass it through several (active and passive) stages that eliminate excess noise. The VCO device that I am working on is a single electronic (rack mount format) component that is part of the stage that eliminates high frequency noise (in a range of ~10kHz to 100kHz). The VCO takes as input a DC error signal that tells how far the laser is from a target/reference frequency. It turns this DC signal into an AC (RF) signal who’s frequency is modulated proportional to the DC voltage. The AC signal is used to drive an acousto-optic modulator (AOM) that shifts the frequency of the laser’s light by the frequency that it is driven with, thereby “locking” the laser to the reference frequency.
We anticipate that we will need to modulate the laser’s frequency by plus-minus 1MHz. What makes this complicated is that any VCO that can be purchased commercially (they’re essentially diodes that have a voltage dependent capacitance) has way too much intrinsic frequency noise–we’d end up introducing a second noise source into the laser rather than eliminating existing noise. To get around this, we start with a VCO that operates at much higher frequencies than we need (this typically means a higher signal-to-noise ratio) and divide the signal down in frequency, thereby dividing down the noise by the same amount. In our setup we start with a 1GHz signal that we can modulate plus-minus 130MHz and divide it down to an 8 plus-minus 1MHz signal (our target frequency gain). Since the AOM needs ~80MHz to operate, we then mix this signal with an extremely stable reference signal from a crystal oscillator to obtain an 80 plus-minus 1MHz signal with low frequency noise–at least in theory!
The VCO is in the prototype stage so I’ve spent the last several weeks working out bugs in the design. It was initially laid out entirely on paper (CAD in reality) and specifications for custom parts were sent off to manufacturers. We’ve had several issues with the physical layout of components (you can’t fit two parts in the same space in real life) and I’ve spent some time correcting resistor values on this chain of op-amps. All things considered, I’m quite impressed that my advisor made so few design errors, given the complexity of the device.
I have also been testing for, characterizing and eliminating noise sources in the circuitry. I’ve replaced a bunch of noisy (probably blown) op-amps and have consequently become fairly good at delicate soldering. (I replaced a ridiculously small chip the other day…about 1/4 inch square, with 10 pins on two sides.)
As of now, I’m waiting on some parts that have yet to arrive before I can do any more meaningful tests. I have a project report due next week, so it’s actually nice to have a little downtime right about now. Once the parts arrive, I’ll be able to start assembling a second VCO (LIGO has two interferometers after all) and I’ll be able to do more extensive noise tests and in addition to side-by-side comparisons between the two identical (hopefully) boxes.
I have to admit that eastern Washington is not quite as fun as it sounds like Germany is, but the local farmer’s market is quite nice and we’re a short drive from the mountains (where I spent a weekend camping out, see picture). I’m thinking I’ll spend a weekend at Hells Canyon sometime in the future when it’s not too hot.
Posted on July 2nd, 2009 No comments
Hello people who are interested in Germany/Joey/Physics!!
!im sorry, but my posts are always super long…
So a bunch of exciting stuff has happened since the last post. So I will start Friday June 19th, about 2 weeks ago… I had just received my train passes from DAAD (the people who are paying me) which will allow me 5 free days of travel within Germany. I was thinking that I only had a few weekends left and thus I needed to use 2 of those passes and go somewhere awesome. Thus, around midnight Friday, I decided I wanted to go to Munich (Munchen in Germany) on Saturday. In the morning I got up, packed, booked a hostel, put on my running shoes and ran to make an 8am train. I must say, I made pretty good time from my room to the train station, and the train literally left less than 40 seconds after I got on it. My legs were still shaking when I had to change trains in Frankfurt about 40 min later!
Eventually I made it to Munich, checked into my hostel, and went about trying to find stuff I’d heard about that was cool. After a while of being lost underground (subway tunnels and such) I was able to make it to the famous Nymphenburg Palace with the help of some super-nice german people. It was beautiful and amazing and it had a garden which was over 500 acres. It was so strange to be walking down a busy street in Munich and then suddenly be in front of an astounding sight like this! I spent a little bit of time walking/being semi-lost in the garden and looked around the palace before moving on. Soon after, I was lucky enough to see a group of street performers composed of a cello, a stand up bass, a flute, and a mini-grand piano!! It was really cool!
From there I saw some statues and other landmarks, before stumbling across the Residence, which was the home of the rules of Bavaria for hundreds of years. I did not mean to find this (i was looking to find a theater and see a play) but it was amazing. I never went inside, but instead just admired the myriad statues and the great architecture outside. I walked around it for hours, passing gardens, fountains, and other incredible sights. There was a moment when I was in the middle of a garden in a small, ordinate pavilion while a street performer was playing solo violin and a man was painting a picture of him. The sun was setting behind a palace and it was all breathtaking.
Nothing else spectacular happened that day, and I again spontaneously decided to take a train in the morning. This time the train was at 7am and went to Garmisch-Partenkircken, a small town essentially in the Alps. I spent a really long time walking around the town and surrounding area. I eventually ended up at the top of the tallest mountain in Germany (with a little help from a train)!! It was almost 10,000 ft up, but I couldnt see much of the famed panoramic view of the Alps due to clouds. It was actually very disappointing… but I did walk on a glacier for a while! I finished off the weekend with a bit of shopping and I got home around 2am. Overall it was a great weekend and I really liked exploring so much stuff on my own!
Okay, so then I was back at work for a week. Early in the week I finished another program, which I talked about in my last blog post. It uses a first order partial differential equation to model neutron stars. When I was done with the program and had checked everything, it was still giving dramatically wrong results. I spent the entire remainder of the week checking units and algorithms in this program. We wrote up a mathematica script which could do some of the same things and our program agreed exactly. I checked several places within the program by computing values in multiple ways and comparing them. After a while my PhD student also started looking at it and determined that my program was probably right, but we were just missing some equation that is supposed to be “understood”! We still haven’t figured it out…
During this week the final few RISE students (RISE works for DAAD, and together they give us money) got here, so now there are 10 of us. There are 8 biology people and 2 physics. There is another physics person!! She is from England and she is hardcore experimental… so she didn’t really know anything about my project at all (because she is experimental… not because she is from England!). She mentioned that she wants to learn fortran, and I had to hold my tongue to not tell her that it is the devil, because no matter how much I dislike it, it is the standard in a lot of physics right now and if she is only going to know one language that should be it.
It was, overall, a pretty uneventful and frustrating week at work… so now I will skip forward to the weekend! I wasn’t sure what I was going to do until about 11:30 pm on Friday (I sense a pattern…) but then I decided to accompany some of the other RISE students to Hamburg. It was an 8 hour train ride, because we opted for the super cheap tickets (with a lot of train changing) and because we missed one train (which only added 1 hour). I had ordered some burger king and the lady was taking a while, I said we should abort but the other students thought we had time…
Anyway, Hamburg is a really cool city! It is a port town, and the people equally like fish and pirates. We got a hotel which I thought was really cool, because it was so small and had cool pictures everywhere, but the girls thought was a little sketchy, for the same reasons. Apparently the red light district in hamburg is some sort of historical big deal, and a thing called a “whore tour” is offered, where a woman dressed like a whore from hundreds of years ago shows you famous old brothels and tells interesting facts. I think this would have been hilarious/awesome/uncomfortable/memorable, but it was too expensive. So we toured some boats, some churches, a WWII memorial, and miniature wonderland and we also climbed a tall tower. Miniature Wonderland is like a model train set times 10^7! It was really awesome and through random confusion and awkwardness I was able to look at it for about an hour for free! Its kinda a long story…
So there is a flea market known as “the fish market” at 5am, and thus we decided to stay up until then! We went out to dinner at an awesome Italian place where I ordered coffee and everyone else ordered water, but the guy made fun of me and brought everyone beer! The two girls who went were really into going to clubs, so them and the other boy who went and myself ended up at a dance club all night. Its not really my scene, but it wasn’t Casey’s (the boy) scene either so it worked out. The name of the club was HALO, which was awesome. Oh, and we passed “the doll house”, which was the nightclub recommended to us by the ~40 year old woman at the travel information center, and it turned out to be a strip club!! From there my subpar german got us to the fish market, but everyone else was too tired and lame to stay up so we went to the hotel and slept for 3 hours.
The next day we ate free breakfast, checked out the motorcycle convention going on at the time, and went to the awesome hamburg zoo. I fed an elephant and a giraffe!! Also, in a lot of places the animals (ie the elephants, mountain goats, giant rabbit creatures, …) were not separated from the people at all! It was really unsafe/cool! It was fun and there was also a large guinea pig village with a church, windmill, barn, etc…
From there we ran to make our train. We passed a taxi that I wanted to hail, but the other students told me not to. Oh how I regret that moment… We missed the train and would have made it if I had said “screw you guys, hey taxi!” It would have been awesome… well, we just had to wait 1 hour for the next train, and then we came back home to Giessen!
Oh, and on the trip I finished the 5th book ive read since ive been here! It is nice to have some time to read… not like at school where I have to do homework all the time! Next I’ll be reading GEB, and I’m really excited! Jeez this post is getting long…
So then this week started! We have given up on fixing the code from last week, and my PhD student said he trusts it and will figure out what we are missing sometime. So I started a new project, and he said “I know there is not much time left, so I don’t know if you will have a chance to finish it, which is fine.” To me that means “I CHALLENGE YOU TO FINISH THIS!” Thus, I am now in a race to create code that will find phase transitions in nuclear matter with 8 particles. It sure would have been cool if I had taken critical phenomena last semester… The code is going alright so far and I have worked on it a bit at home since I was challenged to complete it. I’m getting okay shapes for the curves, but the magnitude is off by a lot. It is probably a unit thing and I feel pretty confident that I will have it all worked out in a few days.
Tomorrow is the annual theoretical physics summer excursion! This year the excursion consists of riding bicycles between beer gardens! Yay! Then yesterday I learned that we are riding almost 50 miles! I haven’t ridden a bicycle more than from Tom & Ian’s to campus (not even 1/2 mile) since middle school… oh no! Eh, I’m sure I’ll be fine… but maybe all the beer gardens won’t help!
You’ve almost made it to the end of the post… just hold on a little longer!
So here is what I’ve got left ahead of me:
-bike trip tomorrow
-weekend in Berlin with my PhD student
-3 days of work
-4 day RISE conference and hanging out in Heidelberg (beautiful german city)
-1 day of work
-1 day to pack/check out of my room
-come home on Wed, July 15th!!!
Wow I only have 4 days of work left! It’s going to be a challenge to get this program done! Anyway, you’ve made it to the end of this blog post! I’m sorry it was so long…
Posted on June 23rd, 2009 No comments
The past few weeks have been full of ups and downs.
Let’s start with a downer. I walked out to my car a couple mornings ago to find the rear windshield smashed out by a rock, which was still lying serenely in the backseat. My innocent blue Chevy was sitting amid a sea of vehicles in a campus parking lot, yet mine was the only one targeted. Luckily, this is Arizona, so I didn’t really need to worry about rain for a while before I could get the windshield replaced (at a cost of $230). I never really expected Flagstaff to be a dangerous place, even after getting my windshield smashed out, but just today one of my housemates was biking along a trail winding through the southern part of the Northern Arizona University campus when he came across a couple doo-ragged guys beating the crap out of each other in broad daylight. Maybe they were just practicing?
On the upside, I had my first real mountain biking experience last weekend. A couple friends and I biked 24 miles from campus to the top of a mountain looming 2,500 feet over Flagstaff and back. The mountain has a couple of peaks, all of which have a huge array of antennas and a watchtower on top. We played leapfrog with a more experienced mountain biker as we took a windy, switchbacky, pot-holed service road up the mountain. We asked him to recommend us another trail to get back down, and he pulled out a map and pointed. “You guys want just a little technical? A little taste of downhill? Then this is the trail you want.” The trail was rated one X (on a scale from one to three Xs, with more Xs indicating a harder trail), but looking back I think the Xs may have actually been skull and crossbones. I asked what trail he was taking back down. “Oh, my trail isn’t even on the map,” he said. This guy totally overestimated our skill level – the trail was deceptively easy while it was level and following a ridgeback, but soon it plunged headfirst down the mountainside. The trail was littered with logs, roots, and giant rocks, not to mention it was extremely steep and narrow… if you took a rock the wrong way you’d fly off the mountain.
Every Saturday we’ve chosen a new place to explore. On the first weekend, we hiked into the bowels of a blown-apart cinder cone, then crawled into a dormant lava river tube. The next weekend, we hiked around in the Red Rocks desert around Sedona, world-renowned for its “vortexes” that emanate mystical, healing energies. This past Saturday, we went up to the Grand Canyon. We were stuck on a shuttle bus during a thunderstorm, but decided to go ahead and start hiking into the canyon anyway. We were the last ones to hit the trail before the storm, so by the time the clouds burned off an hour later, we had that much time to spend in solitude eating lunch and chilling out at the tip of a ridge jutting into the canyon. The views were absolutely stunning, 360 degrees around. The floor of the outer canyon, formed by the material eroded from the collapsing rim walls that has washed down to the river, had the color of guacamole with all of its shrubby, dusty plant life. The Colorado river itself was so deep in the inner canyon that you can’t even see it unless you hike a couple miles down from the rim.
On Sundays, one of us cooks for all the others. We’ve had steak and potatoes on the grill, fajitas/quesadillas/margaritas, and chicken puttanesca. All 12 of us astronomy interns (four REU students working at Lowell Observatory, five REU students working at NAU, two MIT students, and one student working at the Naval Observatory) have become very close in the past couple weeks. I bought a flat-screen LCD TV, so everyone gathers at our apartment to watch movies and party on the weekends. We play a sport just about every day – volleyball up at Lowell, basketball and soccer down at the NAU campus. I’ve become known for a couple moves in volleyball, including “the hammer” and jumping up in the air to spike when it’s completely unnecessary to jump at all. This kid we played volleyball with even asked if I was a martial artist because of the way I chopped and punched at the ball, then asked if I played tennis because of the way I served.
I suppose I should say a few obligatory words about my research. Last week I wrote my first program. Well, scratch that… I wrote my first program in a decade. I taught myself Java and Basic when I was 13 while I was grounded from my computer games for a month, but I haven’t programmed since. My research advisor was gone to a conference in Canada last week, so I used my down time to teach myself FORTRAN (the standard for scientific applications) and IDL (a proprietary language used extensively by astronomers for data analysis and visualization) and wrote a couple programs from scratch for my research.
One of my programs allows me to overplot contour maps of geometrically aligned images observed at different wavelengths. I’ve spent a good amount of my time exploring these images, some of which have such high resolution that we can see an incredible amount of structure in the core of the galaxies too. Some of these bright “knots” look like stars, but we can’t be absolutely sure what they are until we get spectral information in order to determine their redshift or until we correlate them with pockets of gas from 21-cm radio data. I’ve been experimenting with point-spead function (PSF) fitting in a program called IRAF in order to subtract foreground stars across the face of a galaxy in order to compute accurate surface photometry – that is, how the brightness of the galaxy changes with radius from the center – just in case we figure out if the knots are indeed foreground stars or are bright, star-forming nebulae within the galaxy.
This week, since my advisor is back from Canada, she’s teaching me how to run another data reduction program called AIPS in order to perform the monumentally challenging task of building spectra and contour maps from radio interferometric data collected with the VLA (the big antenna dishes seen in the movie Contact). Once I know more about it, I’ll give an overview of interferometry in my next update, but so far it is clear to me that radio data will provide us a huge amount of information about the star formation in our galaxies, as well as about the bulk motion and turbulence of the gas within them.
Well, I’m spent. Here’s some pictures:
Posted on June 22nd, 2009 1 comment
Greetings from the deserts of the Pacific Northwest! Yes, I said deserts. Washington State has the reputation of being a very wet and rainy place, so you wouldn’t think that there’d be any deserts anywhere near it, much less in the state itself. Eastern Washington however, is very dry. As they say here, the Seattle area magically steals all the rain…but it’s no magic, just mountains and a bit of thermodynamics!
I arrived here in Richland, WA (my REU town) after two weeks and one day on the road. I drove ~9,000 miles total and my truck really needs an oil change. I visited the Grand Canyon, Yellowstone, the Redwoods and Olympic National Park among other things. I took few pictures of the bigger tourist sights (eg old faithful, Grand Canyon)–they are some of the most photographed places in the world after all. I will mention what the pictures don’t tell you: old faithful smells like a giant fart because of the sulfur. It was overall, a really great trip. I really enjoyed the scenery in the Northwest, but Wyoming gets the overall top spot for favorite place.
I’m writing after my first full week here at LIGO. So far we’re working on settling in and getting the necessary paperwork done. I’ve been given a look at my project: mostly I will be building electronic equipment. I was handed a stack of circuit diagrams that I need to assemble. At this point I need to give a big thank-you to Dr. Goggin’s electronics class, without which I would be pretty lost right now.
The tumbleweeds around here are quite a sight. For the benefit of those of you who are, like me, from back east: a tumbleweed is a sagebrush plant that has died and been dried out. Eventually the stalk breaks in the wind and the whole plant blows across the desert, often for hundreds of miles. The sagebrush grow fairly round, facilitating their tumbling. They range from about the size of a softball to larger than a beachball. Cars on the highway that are traveling directly into the wind often collect a large pile of tumbelweeds on their grilles. Overall I must say that I find them quite comical–there’s just something about how they bounce across the desert…
It’s very dry out here. The sky one day was brown from blowing dust and they have signs along the road telling us that it’s illegal to throw burning material out of your car. We were notified one day over the PA system that there was a brush fire along the main road that runs between the site and the town, and that we all should take an alternate route home. This of course prompted stories from the staff of brush fires, which apparently turn tumbleweeds into hurtling balls of flame.
LIGO itself is pretty amazing. For those who need an introduction, LIGO is a giant michelson interferometer with 4km long arms. It was built as part of an attempt to detect gravity waves originating from distant, energetic cosmic events. A passing gravity wave moves the mirrors in the interferometer, causing a detectable change in the output light. The difficulty in the whole project is that we expect (based on the predictions of general relativity) that a passing gravitational wave will deform the distance between the mirrors in the 4km arms by about 10^-18 or 10^-19 meters depending on the strength of the source and its distance from earth. What is 10^-19 meters? well, it’s about a billion times smaller than the diameter of an atom or a thousand times smaller than the diameter of an atomic nucleus. Insane.
Most of the work done here at LIGO is focused on eliminating sources of noise in the interferometer. To a large degree the entire LIGO project is a massive exercise in control theory. The complexity of the systems used to keep out external effects is amazing. The equipment is first built on its own concrete slab that is physically separated from the main foundation and rest of the building. Things like the HVAC system are even located a good distance away from the interferometer to reduce vibrations. The optics are isolated from the ground by pendulums so that a vibration in the ground will be damped out. The pendulum isolation system is only effective for higher frequency motions (> ~1Hz). Even though LIGO is not trying to detect gravity waves with such low frequency, it is still necessary to counter low frequency motions so that the arms are maintained at a resonant length for the laser light inside (the interferometer is “locked”). Effects such as tidal stretching of the ground and thermal expansion during the day are some of the main causes of low frequency motion of the mirrors. In fact, the effect of tidal forces is about 200um over the 4km length of the arms–a big deal when you are trying to detect motion on the order of 10^-19m! Low frequency motions are compensated for by servo motors that move the mirrors to keep them at the correct distance.
Oh ya…we have really big lasers. LIGO is currently using a 30W 1064nm laser, which will be upgraded to a 200W laser as part of the Advanced LIGO project’s improvements. The quantum mechanical signal to noise ratio goes as N/Sqrt(N) where N is the number of photons, so increasing the power will decrease this type of noise. Since LIGO is a power recycled interferometer, the amount of power bouncing around in the arms can be in the neighborhood of 10,000-100,000W. This massive amount of light causes thermal heating of the mirrors, which deforms them and changes their optical properties. To keep the mirrors functional, a secondary laser system was built with the sole purpose of heating the mirrors in a pattern that will compensate for the thermal deformation by the main laser. For example, the second laser might by aimed into an annular pattern around the main beamspot. (in keeping with the philosophy that any problem caused by lasers can be solved with more lasers.)
I think I’ve rambled enough, sorry for the length of this post! I do have to give a big thanks to Ian Noble at ISU who was nice enough to give me a place to sleep and a free meal when I drove through Pocatello, ID. Also Ian, I passed a sign when I got out here that said I was entering the most potato producingest county in America, and I’ve been told that the area here produces more potatoes than even Idaho…HA!
Here’s some pics from the latter part of my road trip: (thumbnailed this time!)
The Grand Canyon:
The Olympic Mountains in Washington state:
The Oregon Coast:
The snowblower was very colorful:
Mountains in southern Colorado:
Mt St. Helens:
A buffalo on the road in Yellowstone National Park:
Posted on June 21st, 2009 No comments
It seems that today is a major update date for the REU blog so far, and I figured I should make this day as big as possible. When we last left off, I was about to present my findings to everyone in the program. That all went ok. If there is anything I can handle, it is tongue and cheek public speaking events.
After that began my weeklong struggle getting our actual experiment up and running. We tried to start setting up our stuff in the beam room, but we had to wait until another professor’s 100 hour beam experiment was over. This lead to me doing any sort of calculation that we would need. Cross section calculations to see what the probability of a photon–> pair production happens in air. What are the count rates we should expect to get for running the beam at such and such specifications. Basically, we wanted to know just how many electrons and positrons would happen in each pulse of the beam. Ideally, it wouldn’t be that much, so we could be sure that any time we get a hit in both detectors, we could then assume the electron and positron came from the same photon.
The number we got was extremely large, so we had to add in a bunch of collimation to our beam line to get count rates low. Still, this wasn’t that much work to do, and we were basically just waiting to get the beam time. The downside of having your own linear accelerator at your school is that there is a lot of negotiating between professors on running the beam, since none of them have to pay to use it like an outside person would. The beginning of this week, we were set to go in the beam, but the other professor (who has a huge gov’t grant) was in a some sort of underground bunker talking to the military in D.C., so we couldn’t get a hold of him to ask if we could use the beam. There are some high school kids doing a sort of physics summer camp here, so I ended up helping them make more detectors because they were as lost as baby sheep with the circuit boards.
Finally, we had beam time (dedicated beam time so we could do whatever we want) on Friday. Yes, that means I had a miserably slow week as far as work goes. We were ready though. I had to move a lot of lead, aluminum and graphite bricks around to protect our detectors getting fried, but it was really worth it. I was so ready to do physics. Friday comes along, and everyone who is involved with he project comes down to the countroom to see the initial launch of the pair spectrometer everyone has worked so hard on. We set up a nice circuit to measure coincidences in our two detectors.
The beam starts up and we start getting flashes of data. Or so we thought. It was just background cosmic rays. The beam didn’t started because they had a problem with the cooling system. 7 minutes later, they get it going, and we are seeing peaks on our oscilloscope. For about 20 seconds. “Something is wrong with the cooler still, I need to call the supervisor guy.” 30 minutes later. “We found the problem. A switch was stuck, and it needs to be replaced, but it will work for now.” The beam starts up and it is working. We see hits flying in…for 45 seconds. “Somethings wrong. We need to call a repair guy. It will be down until 1.” Ok, go to lunch and then come back ready to go.
The experiment is a pretty easy result. If we have pairs being made, we will see the majority of coincidences hitting the two detectors at roughly the same time. It won’t take long to know if we got it right, so losing the morning isn’t that bad. A hamburger, fries and ice cream cookie sandwich later, we’re back in the countroom. “Yeah, we fried a circuit board. The guy who is the electrical engineer for the beam is in Germany in Tuesday. We can’t run today.”
To sum it up, I am in a limbo of nothing to do. Joey, since you’re in Germany, if you can find an electrical engineer from ISU named Chad, could you send him back to the states for me? Thanks.
Sometimes, it sucks to be an experimentalist.
I’ll have the fun stuff I’ve been up to in my next post. I’ll probably have a ton of free time to blog this upcoming week.