SPS REU Blog

VCO

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.

The VCO:

Northeast Oregon (panorama shot):

keine titel.

Hello people who are interested in Germany/Joey/Physics!!

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!im sorry, but my posts are always super long…

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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 5^th 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 15^th!!!

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…

Have fun!

joey

Smashed windshields, Millenium Falcons, microwaved light bulbs, canyon-jumping good times.

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:

My shattered rear windshield with mountains in the background.

We're chilling out eaten snacks at the top of a mountain overlooking Flagstaff.

A couple of the other students I work and live with hanging out in the Grand Canyon.

Overlooking the Grand Canyon. This is not a place for the faint of heart.

I am renowned for my floppy hat. I gave my jacket to one of the girls, so that hat was all I had to protect me from the rain.

I'm leaping like a flying squirrel into a creek at the bottom of a gorgeous canyon.

Mashing potatoes the cheap college student way... with a beer bottle.

The Millenium Falcon is airborne! (Don't worry, it's just a kite we spent an hour building.)

Sweet glowing light bulb in the microwave.

LIGO is crazy, and other stuff

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:

Hoover Dam:

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:

Beamtime

Hey everybody,

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.

deutschland ist toll… aber Kirksville ist auch gut?

Hey!  I haven’t posted in a while so get ready to read way more stuff about me than you actually care about!

First off, do you guys remember when Truman hosted that awesome party that over a thousand people came to and everyone had a really fun time for many hours?  Oh wait… that only happens in Germany!  So yeah, that happened here.  The party was in a large field and there were no less than three soccer tournaments going on.  There was volley and sac racing too, and lots of slightly overpriced (but still tasty) german beer.  There was also a beer crate stacking competition where you had to climb on top of the crates you’d already stacked to put more on top, which was super awesome!  Then there was a dancing/break dancing/other stuff show which was really cool and had really different creative stuff.  I was there from 6pm to 430am which was really fun, and there were tons of people there when i showed up and tons still there when i left.

Then, last weekend, some of the other RISE students and I went to Koln, or Cologne.  It was really fun!  On the first day we saw the dom which is a giant church.  We also saw an old nazi prison that had been converted into a really interesting museum.  My favorite part was the writing scratched on the wall of the tiny tiny cells (which held 30 people, 28 more people then i had guessed by looking at them!!).  Among the best were “Nazi Assholes”, and “Dear prisoner, you can endure through anything, and thus you can endure this.  Keep your head high!”.  The guy who wrote that last one must have been awesome.  From here we ate some food at the Rhine, and noticed the German phenominom that is the ‘beer bike’.  A bar with wheels and petals!  We walked about town, lost track of time, and had to run across the whole town (with me jumping walls because i fell behind to take a picture of a mr t poster) to catch a boat.  We took a really cool tour of the rhine, which i slept during.

This was followed by making our way back to the hotel we had booked, which was literally in the middle of a field out of the city.  We had to walk through the woods to get to it.  Then, around 11pm we made our way back into the city!  We enjoyed the German tradition of buying beers at corner stores and walking the streets drinking them while looking for bars and getting lost.  Okay, I don’t know if its a German tradition, but we did it anyway.  The next train back to our hotel was at 5am so we stayed out until then to avoid the cost of a cab, but we accidentally took a train in a circle and got confused so we just took a cab anyway.  In the course of the evening we spent a lot of time just walking around, met a homeless man with a giant joint who was frustrated because someone took his “rook-bag” and he hoped he could randomly see that person tomorrow so “I… I will push my fist so hard into his face!”, and some cool british guys, one of which said to me “you have the coolest beard and haircut that I have seen the whole past 2 months I’ve been in Germany,” so it was a pretty fun evening i guess.

The next day we got up and went back to the dom.  We looked at the underground caverns and stuff it has.  Building it began in the 1200’s and didn’t finish until sometime in the 1800’s!  We also saw a fancy box that is said to have the remains of the 3 wise men in it, which was cool.  Then we proceeded to climb over 500 stairs in a tiny spiral staircase (it took a LONG time) to see the worlds largest free hanging bell.  The bell was closed so we didn’t get to see it… but it was still a super cool view of the city!

We then finished off the trip by visiting the chocolate museum!  It was actually really interesting but we didn’t get as much free chocolate as I would have liked… Then we traveled back to Giessen and went to sleep!

Well, during this time I’ve also been going to work.  As always I’ve just been programming away, which is a lot of fun!  While I really don’t like FORTRAN very much, I do like programming a lot!  I’ve pretty much finished the program that I had been working on.  We have a file with the parameters for different nuclear models, and I have the program set up to take whichever models the user specifies and create data tables for density, effective mass, effective chemical potential, energy density, free energy, entropy, chemical potential etc for each particle (there are 8 particles, include particles with strangeness /neq 0) for given ranges of total density and temp.  It works really well and it is fun to look at the 3D graphs in gnuplot.  Using this program we found a few behaviors that were not expected including an area which had a continuum of solutions.  Andreas was able to theoretically explain this, and it was really cool!

Since then I’ve been working on a new program concerning neutron stars.  Neutron stars can be described by the Tolman-Oppenheimer-Volkoff equation, which is a first order pde expressing d(pressure)/d(radius) in terms of enclosed mass, pressure, and radius.  I am using the 4th order Runge-Kutta method to numerically evaluate the equation.  It is kind of a pain because M is expressed as an integral in terms of radius and energy density which we also needed to solve numerically.  This is even more of a pain because we don’t have an analytical way to obtain energy density from p so we have to use newton’s method to find rho (total density) for the given p and then use that rho to find energy density.  Well, i actually finished this program today, but it basically took me all week and a lot longer than I had hoped.  The program uses a given pressure for r = 0 and evaluates pressure at different r, until reaching p = 0 (the surface of the star) and then returns the total radius of the star and its total mass.  I just finished it before leaving work today, so I haven’t had a chance to check the results at all.

Oh!  There was another program I wrote sometime that I totally forgot about.  In between writing these two I spent a few days  writing a program which takes certain facts about neutron stars to act like my first program but not require rho as an input.  It was really cool and uses Newton’s method in 24 dimensions, which was kind of a pain, but not too bad.  It works well and turned out good I think.

The PhD student which is my mentor said that he wanted to give me my own side project, and I’m glad that he did.  It has been cool acting mostly on my own doing research which is important to his, but somewhat distinct.  That being said, once I finish this neutron star program I will be done with everything which he had set aside for me, so we don’t know what I’ll be doing…

Now lets stop talking about physics again.  I think that I will be going to the Alps tomorrow, but maybe not, I haven’t decided.  I really want to go somewhere but I don’t know where… I suppose you, dear reader, will hear about it in my next post!  I really should post more often, because this one seems very long…

UNRELATED SUBJECT:——————————————————————–

So I have been thinking about my schedule next semester a lot lately, and I think this might be a good place to get some opinions.  I’m afraid I might be doing too much and I’d like to especially hear from anyone who has taken these classes.  My classes, in order of probable difficulty, are:

MATH 465 — differential geometry with Easley

PHYS 580 — quantum mech with Edis

CS 460 — computer graphics with Neitzke

MATH 564 — adv linear algebra with garth

PHYS 490 — senior research with goggin

PHRE 186 — intro to phil with chad mohler

Let me know what you guys think!  Any input would be greatly appreciated!

———————————————————————————————

Well, I think I did a good job conveying all of the interesting stuff I’ve been through without being too long-winded… Anyway, everybody keep up the good physics and good luck with everything!

have fun!

-joey

Nanowires made, waiting for SEM Tuesday

We finally fixed the problem we’d been having with making nanowires, which turned out to be a broken reference electrode.  Ideally, the part can take a consistent measure of potential differences regardless of what it is submerged in, which is important to (i) successful electrodeposition and (ii) consistency.  So while our early nanowire growths were (as the kids might say) full of fail, with a new reference electrode, all became well.

I wound up making 8 different samples, including one pure Ni and one pure Fe, as well as six intermediate values.  The pure Fe one seems little janky.  Due to the electronegativity differences between Ni and Fe, the final composition ratios will end up a bit random-looking (not a clean 0:6, 1:5, etc.), but if we compensated correctly, they should be dispersed fairly evenly.

Tuesday, I will get to go to SIU’s imaging center where I’ll assist our lab’s post-doc in taking some pictures of the wires.  This will be very similar to the last time I encountered an SEM, except that instead of one successful growth we have eight; it will probably take a long time.  Then we’ll leave the samples with the imaging people to perform electron dispersion spectroscopy (EDS) to find the ratio of Ni to Fe in each of the samples.  Here’s to hoping no Fe crept into the “pure Ni” sample!

Yesterday, I etched all of the samples.  It’s a fairly simple process, but it took a few rounds of practice to get right (I will only be sure that I did in fact get it right on Tuesday).  The templates we’re using dissolve in NaOH.  Today I prepared them for the SEM, and they are presently good to go.

Magnetic measurements have begun, but I haven’t received all of the necessary training yet.  Here’s to hoping for fast progress.

The project has received an addendum.  Once I find the alloy with the most favorable magnetic qualities, I will take the solution, make more samples of various diameters, and find an optimized diameter.

The last week has been rather odd.  Fortunately, everything has been working (finally).  However, there was an electrician in the lab doing rewiring on Tuesday and Wednesday which hampered progress.  Wednesday night and yesterday, I did a lot of work to get all of these samples fabricated and prepared, but that left a meager workload for today.  This is fortunate because I had a minor alarm clock malfunction.  It is also unfortunate because I find myself writing a blog entry instead of laying down some science.

Happy Father’s Day.  I get to spend the weekend in St. Louis with my family.  I’m going to experiment with route selection from Carbondale to St. Louis.  Illinois State Highway 13, you had better be worth it.

LANL*

Hey everybody!

Sorry it’s been so long… We had quite the experience trying to get a steady internet connection set up in our apartments. Anyway, this would be the much awaited ‘physics post’ for my research experience (although I’ll probably take up more space writing about non-physics stuff).

For those of you who hate condensed versions and like the drawn out version with way too many technical terms, you can see what my project is all about here. This is the article that my mentor (Josef) and his colleagues have already published. Here is the condensed version:

My project’s goal is to develop a new method for calculation the magnetic drift invarient L* used in many space weather applications.  I’m sure many of you know what L* is, but here’s a little refresher straight from Josef’s paper: ‘L* is dircctly proportional to the integral of the magnetic flux contained within the surface defined by a charged particle moving in the Earth’s geomagnetic field.’ The problem that we face when calculating L* is that, typically, an L* calculation can require ~10^5 calls to a model. This takes a LONG TIME! To put it in perspective, each call takes about a minute on the computers here (wait ’til I tell you about the cluster I’m going to be working with!). Doing some simple math (1*10^5), that would take 100000 minutes! I don’t know about you, but I just don’t have the time to sit around and wait for that. What Josef has been working on (and what I’m now working on), is to develop a neural network surrogate model that can calculate L* millions of times faster than the standard direct integration techniques. The neat thing about a charged particle’s motion through Earth’s magnetic field is that it remains ‘trapped’ in certain places (provided it does not get lost in the Earth’s atmosphere or travel past the magnetopause). The particle exhibits three types of motion - gyro, bounce, and drift. The gyromotion is the partcle circling around a magnetic field line. The bounce is the particle ‘bouncing’ up and down along a magnetic field line. This motion depends on the particle’s pitch angle with respect to the magnetic field line. The last motion is the particle ‘drifting’ around the Earth, parallel to the magnetic field lines.

That’s about it for the physics part - my main job here at LANL is to train a neural network (a big-@$$ computer network) to learn what results come from what input parameters. I think about it (not sure how correct this is) as giving the computer examples and building up its ability to instinctively spit out an answer. Someone who is more computer-savvy might want to explain the exact workings… So basically, my job is to provide the network with many real examples (from data collected the past four decades) and then validate the results with other sets of data that the network hasn’t seen. LANL came up with a clever name for their model of L* - LANL*!

So far, I’ve been stretching my brain to learn Python (yes, named after Monty Python!) and understand what Josef already has written. I have already written a couple of scripts that call upon the 40 year data table and organized that data into dictionaries in Python (basically a list with many key-value pairs. ex: key-value=’Year’-1963). Then I also wrote a script that transforms TAI (I think) time value, which is basically seconds since the start of 1958, into a human-understandable reading of day-month-year-hour-minute-second. So far it’s been a lot of fun using Python and troubleshooting on my own. I highly suggest all computer language illiterate people to at least try some simple stuff with a language. I’m not claiming I’m an expert, but it has been a very enjoyable experience so far, not to mention it will be very useful in the future.

This week was very exciting for me because I was finally told to log in to the computer cluster that I will be working with. I don’t know how much I can tell you about the cluster because I haven’t been able to find public info on the web. It is only described on LANL’s internal network. But I can tell you that it is monstrous. I get nervous everytime I log in to the cluster through my terminal. Oh well, maybe I’ll get used to the idea of having tons of computing power at my fingertips…

Well, enough talk about work. This past week we went hiking to three different places. We went up Pajarito Ski Area, down Hamilton Camp Trail, and up Cerro Grande in the Jemez Mountains. Tons of fun. I just realized I don’t know how to put a picture in here… That’s sad. A little help, Isaac!!

So, I guess I lied when I said there would be more non-work writing. I’ll get some pictures up and expand on my social activities once I figure out how…

Hope everyone is enjoying their summers!

-Martín

Let There Be Nanowires

Since my last entry, I have been making Ni nanowires.  Today, I went to the imaging center to use the SEM with a post-doc who works with my professor.  Only one of the four samples showed nanowires; the current scapegoat is a poor gold/palladium back coating (and thankfully not my handiwork).  I made two of the solutions for alloy nanowires, which I will test tomorrow.  Overall, the lab work should soon be in full swing, assuming that subsequent nanowire samples do not fail like samples 2-4 did.  I am cautious.  I am optimistic.

Today there was some kind of film crew hippie pizza gathering outside of my lab.  I wish I’d had more of a chance to interact with them, but I doubt there will be a second day of shooting tomorrow.  Note that there was an acoustic guitar, and they made a film in the neighboring lab (plot unknown).

Dorm life is becoming more settled, though it is not quite in equilibrium.  The lack of kitchen facilities is disturbing.  Current provisions include:  off-brand low-fat Cheez-It knockoffs, off-brand low quality Cheerios knockoffs, quick grits, quick oats, brown sugar, 39 cent wheat bread, reprocessed turkey, provolone, 11 cent hot dogs, and of course JIF brand peanut butter.  Also, tea.  Without tea, Carbondale would be but a haze.

I am doing laundry tonight.  Ordinarily I probably would have passed out by now, though last night I was up rather late playing Left4Dead and watching Diggnation.  The laundry machines are very similar to the ones from Truman, but there are no quarter slots.  You have to pay with your ID.  Two of the washers were malfunctioning in some fashion to allow free washing.  It seemed like a great idea at the time, but I believe there was some kind of tissue in the bottom of the drier hidden so as to cover my socks in lint.  I also acknowledge the possibility that this was my fault.  I am hoping that the drier will take care of this, but I fear the problem will be exacerbated.  I must now go to the laundry room to retrieve my clothes.

More Than a Feeling

Greetings, physics persons far and wide!

I finally make my maiden post, updating you on the wonders of physics on the east coast like no one else can! Maybe I’m promising more than I can deliver, but nonetheless, here we go:

I was awarded a position in the REU Program at Boston College, a mid-sized institution (~9,000) just outside the city of Boston that is administered by the Jesuits of the Society of Jesus. This is the second year BC (as you quickly find yourself calling it) has hosted an REU program, and they’re pretty ambitious about it. Week 1 has thus far included a rigorous battery of lectures, most of which center around condensed matter and material sciences, the specialties of the fine faculty here at BC.

It’s worth taking a moment to describe the type of department physics is here: unlike Truman, they are very much geared toward research. When I say that, I don’t mean that we don’t have opportunities or aren’t encouraged, but just that it’s not the focus. That’s hardly the case here where it IS the focus: million-dollar laboratories, government grants, grad students and post-docs, the whole nine yards. They’ve got their own faculty support staff unto themselves (no sharing those staff with Bio, even though they share the building with Biology, and no chemists to be found!), not to mention a big old office and virtually the entire basement to themselves. I’ve been assigned to work with Dr. Michael Naughton and his laboratory team.

Time and time again, I’ve been told that his is the “best” lab, which I’ve come to find means that they have the most projects and grants up in the air at one time, as well as the biggest physical space. Most Impressive Thing So Far: The 43 Tesla Pulse Magnet you have to lock in its own tiny room without any people before firing it. That’s not my project though, sadly. This begs an important question: What is my project? Truth be told, I don’t know yet. The Naughton Lab has so much going on that we decided to wait until a few more things shake out before I get assigned my work.

That mostly depends on how good the sample materials created by another BC lab pan out. A graduate student was examining them just this afternoon over at the Scanning Electron Microscope / Tunneling Electron Microscope facility across the way at BC’s other campus. I myself will be touring that facility with the REU group, and then staying behind after they leave to be “oriented” so that I can go work there if my project requires it! Security’s pretty crazy: foreign nationals aren’t even allowed in, which a priori I take a political objection to, but I’m not above being a little impressed at whatever lies within, that they feel it requires such security.

Following that, I have a meeting with my mentor (Dr. Naughton) and hopefully I’ll have more information about which project I’ll be assigned to by then. (There are a bunch, but explaining them all would be a bit of a waste, and I’d probably maul the science anyways…)

Right now I’m sitting in my little dorm [Note: I was recently corrected that 'dorm' is a pejorative term, with "residential hall" being the preferred nomenclature; ResLife people, you can deal with it. I sleep here, IT'S A DORM]. I share an apartment-kinda-thing (though it’s in a dorm-like building) with three other dudes, though the space we’re in was meant for six. So we each get our own room that was supposed to have two people in it. I’ve been told numerous times that this is “one of the best” dorms on campus. Eh? All I have to compare it to is Truman’s dorms, but I feel like they’d clean up in any such competition. BC has this weird apartment business going for it: having a full fridge and stove and living room is pretty nice… but sharing it with five other people? That’s more than I live with at Truman, and we’ve got an entire HOUSE. Also: I feel like if I took a misstep I might fall though one of my room-walls! Anyways, I don’t wanna complain. It’s a nice place to sleep, and plenty of room, I guess I just expected to be blown away since tuition is so much more expensive, and I was not.

I’ve had limited time to kick it in Boston, so far only one foray to the grocery, and another to get some Chipotle (which I do not hate nearly as much as I expected to) and then see a one-night-only presentation of Pulp Fiction at a restored movie theater, which was fantastic!

Anyway, gotta get to the bus stop at 8:30 tomorrow to get to the clean room, and I’ve caught something of a cold, so I’m gonna get some sleep. More science updates to follow, and I promise right here and right now to keep you abreast of my adventures in Boston proper.