SPS REU Blog

Rainy Idaho=Raindaho

Hey everybody,

It has been pretty exciting to see everyone else’s REUs start up. We are in a lot of cool places, and I like the enthusiasm. I haven’t posted in a while, because my current project has been much of the same thing, and I wanted to at least wait until I was done with this part before I posted something. I guess I should put physics first and then move on to my cool, yet rainy adventures.

I have talked about how my work deals with a pair spectrometer and measuring things with a linear accelerator. Well, for the past week or so, I have had to calibrate (gain match) two photomultiplier tube detectors. What is the deal with gain matching? Well, no two photomultiplier tubes will be exactly the same, and a single PMT will have large difference in measurements depending on the voltage you have running into the detector and how high of a threshold you set for the detections. So, Dave(my partner) and I have had to do a lot of tests in the Laboratory for Detector Science. (Wait until Truman gets one of those)

A single “run” of tests would go like this: we hook up a PMT and setting a radioactive source(I need to wear a radiation badge thing) right next to the detector. Then we want to find out how many counts the detector registers from the source in a set time; we did it for two minutes. We set a threshold for how much energy the particles must have, and then we incrementally (25 volts at a time) decrease the detector’s voltage from 1400 until we don’t get any more hits. This takes about an hour. We had to do a run with three different thresholds, 2 radiation sources, and for both detectors. Factor in some faulty cables, scalar boxes and other stressful things, we were doing this for quite a while. As a side note, it is very interesting to live your life in 2 minute increments. You have 1 minute 50 seconds to do whatever you want, but then you have to get back to work. I’m happy Dave was there. The grad students also taught us a lot about their projects, so I’ve really learned a lot.

When we looked through the data sets for our 12 runs, we were able to figure out a lot more about what voltages to run the detectors so that they have similar count rates. We were also able to find the “plateau” where the count rates were least sensitive to voltage changes. Our Professor asked us to find the Compton Edge for the detectors. Compton edge is basically something in spectometry where gamma rays deposit some energy into the scintillator, the thing that picks up the radiation, even though they escape from the scintillator. The maximum energy of the particle allowed would be the particle that doesn’t escape, and that is the Compton edge.

This meant going back to the LDS and doing the same thing, except we had to collimate the sources by shooting them through a tiny hole in a lead brick and we kept the voltage constant and varied the threshold. This took a lot longer, but we only had to do two runs. Now, we will be presenting our data to all of the grad students and professors, about 15 people who know a lot more physics than me,  who are involved in the larger project in about 2 hours. I hope that goes well.

Now for the fun side of Idaho, or for this last week, Raindaho. It rained here for about a week. It wouldn’t rain during the day, just when we would be leaving dinner after work. A lot of the outdoor adventures have been postponed, like our tubing trip down the Portneuf River. This has left us with a lot of reading (Blood Meridian by Cormac McCarthy is fantastic so far), board games (a lot of late night Monopoly and Clue and Rummikub[Taner, if you read this, did anyone know Rummikub is just Castet?]) and most recently, someone brought a Wii from home (You all know how that ends up).

Before the rain, however, we were able to go hiking up Scout Mountain. I guess this is nothing compared to Nick’s elevation, but we ended up at 6,500 ft, which is about a 2,500 foot climb from ol’ Pokey(what locals call Pocatello). It took us about 7 hours of just constant incline. It started off as a 90 degree day, but remember, it is dry heat at least. Eventually, we hit the snow banks, one of which I fell through up to my hips. If that wasn’t interesting enough, on our way down through sage brush and Aspens, we were caught by rain(this was the beginning of Raindaho week) and eventually hail. This meant that last leg of the trip was through mud. One of the more tiring experiences I have had in a while, but it really was worth it. The views from high elevation are absolutely stunning. These pictures were taken by the professor who took us there and a Ukrainian grad student who had never made the hike before.  I’m going to leave you guys with these, because I can’t really say something that is more beautiful than this.

Until next time everybody (the rain has cleared up, so some good fun should be coming my way)

http://picasaweb.google.com/valeriias/ScoutMountain#

http://picasaweb.google.com/rshapova/ScoutMountain

Greetings from the Rockies!

I’m writing to you from the town of Leadville, CO where there is public WIFI access (what an awesome town!). This is my 5th day on the road and it’s been wonderful. I have 5 states worth of mud on my truck (see picture) and I refuse to wash it until I get home (with the exception of doing the windows while filling up on gas–I need to see the road!).

So far I’ve camped out in central Nebraska, the Black Hills of South Dakota, the Big Horn Mountains in northern Wyoming, the Medicine Bow Mountains in southern Wyoming and the Rockies near Denver. I’m traveling in my small pickup which has a camper shell over the back that I can sleep in. As an impoverished college student, I’ve been subsisting on ham-sandwiches and ramennoodles, camping on public lands and going to state park campgrounds to shower, etc, etc. Public lands here out west are pretty nice, it’s really quiet and you can count on being undisturbed (with the exception of being woken up by a cow sniffing at the window of the truck). For the record, I did get stuck in a snowbank yesterday (it’s June). I carry appropriate tools and getting out wasn’t much hassle–it was quite fun actually.

The weather was fairly lousy the first three days and I didn’t take many pictures because most of the scenery was obscured by rain and fog. Since it’s cleared up I’ve taken more pics. Most of what I’ve posted below is from the last two days.

I have about 10 days left on the road before I have to be in Washington State doing physics. I think I’ll be heading southwest toward the Grand Canyon…

Pictures
The Big Horn Mountains in the Clouds:

Devils Tower on a rainy day:

Rain in the Great Divide Basin of Wyoming:

I camped here:

Rain west of Laramie, WY:

My truck!

Wind River Canyon, WY:

Mountains in the Wind River Range:

Oh Washington, you elusive Devil…

Hey you crazy physics cats out there, this is Travis Grider typing to you from beautiful Washington, which is by far better than Missouri.  It took me awhile to get this setup, as I have for some reason been blacklisted from the physics email list ever since I’ve been going to Truman.  Even as we speak I’m pretty sure I’m still not on it, Joey forwarded me the info from Tom so thank you Joey.  At least once over there you need to drink enough German beer and Apfelwein to get a little tipsy in the pub!  But anyway, I’m doing a cool, laid back REU at Washington State University in Pullman WA, which until I looked on a map figured it would be raining here all washington-like every day, but no, it has actually not rained once in the ten or so days I’ve been here, and has had beautiful skies and a mid seventies temp with a perfect breeze every day.  So when I say it’s better than missouri summers I’m not kidding at all.  Oh and stuff like flowers and trees actually grows here in the summer in abundance too, without scorching heat killing it off at the beginning of July.  It’s in the bottom right hand corner of the state, so it’s very close to Idaho, and in fact I can be in Idaho in like a 8 minute drive.  However, this state is much different than Idaho.  It’s very hilly here and there’s farm land all around, so it looks pretty crazy because they use the hills and the awesome soil here to farm on, so they don’t plant fields in grid shapes, but in big giant circles that from a plane remind you of different colored crop circles or something.  And then crossing into Idaho, the world changes and it all seems kind of rocky and there’s big cliffs and it’s much more mountainous.  So even though they’re hugging where I’m at, there’s a distinct difference in landscape, so it makes sense why they drew the border there I guess.  So yeah, I’ve settled in nicely, and similar to Ian’s, they payed for travel and living and a bunch of money for doing some research stuff, I just need to feed myself, and without sedexo or a car is kind of a pain sometimes.  But Pullman is pretty similar to kirksville, in that it’s basically a college town, except the college is about 5 times bigger, so the town’s scaled up accordingly.  There’s not a ton of stuff to do in the town itself, apart from bars and stuff like that, and it’s pretty dead in the summer, but the Rec center here is awesome and there’s scheduled float trips and hiking and rockclimbing and those kind of things offered which I’m definitely going to do while I’m here.  I’ll make another post about the actual research kind of things I’m doing in a day or two.  Since my actual research is in the field of Materials Science Engineering, there was a lot of reading and catching up I had to do, because although it’s more or less physics-type stuff, the reading gives you an impression that engineers think of things a bit differently than physicists do, and while the physics knowledge helped me digest it easier, mainly because engineering is way easier than straight up physics, there’s a definite separation of thinking styles.  As one of the professors here told me, ‘A materials science engineer is just a physicist who wants to make money with his degree.’  I will leave you with that.  Reading all of the stuff you guys are doing for the actual physics REU’s sounds really interesting and cool, and I wish I would have signed up for the physics REU here at WSU because they get paid about $1500 more, and makes mine seem really easy, but all I can say to that is… Suckas!

Astronomy: the other white meat

Well, after all this talk of neural networks and particle accelerators, I suppose it’s about time to hear from a representative from “the other white meat” of physics. I’m out here in Flagstaff, Arizona, working at the world-renowned Lowell Observatory, whose primary claims to fame are Slipher’s 1912 discovery of high-velocity redshift in the spectral lines of galaxies (which led to the realization that the universe is expanding and, hence, had a beginning), and Tombaugh’s 1930 discovery of Pluto (whose eventual demotion from planethood led to great confusion as to what exactly my very educated mother just served us).

The observatory is still an active, privately owned research institution that regularly hires a staff of summer interns, who also attend seminars at the local Northern Arizona University and live in apartments on the NAU campus. There’s a group of 12 of us from all over the country, and over the past week we’ve gotten really close already. (In fact, a couple of them just finished knocking down some beers to help dullen the pain from basketball injuries while watching Harold & Kumar Go To White Castle. I was busy writing this blog and not following the movie a single bit. Somebody will have to explain the cheetah.)

Now, a little about Flagstaff. Simply put, this town is amazing. I’ve been here a couple times ago to work on research I’ve been doing at Truman, and every time I come back I love it even more. It’s a bit smaller than Columbia, Missouri, but this isn’t your typical Arizona town in the middle of nowhere in the desert. We’re up at 7,000 feet sitting smack in the middle of gorgeous pine forest country. The state’s tallest peaks, which form the outer shell of a supervolcano that blew apart (much like Mount Saint Helens), loom over the town a couple miles to the north, and the whole county is pockmarked with cinder cones and crisscrossed with underground lava tubes.

We’re planning an expedition to the summit of the tallest peak this weekend, which is probably a stupid thing to do because we haven’t even adjusted to the thin air at 7,000 feet while climbing a flight of stairs, much less hiking up another 5,000 feet to the top of a snow-capped mountain. You can see the peaks from 100 miles in any direction, so if my theory is to be taken, the view from the summit should be incredible – on clear days I hear you can see all the way to the Grand Canyon.

The town itself has got everything you’d find in a big city – tons of great restaurants and shopping – but surprisingly it’s got to be the most bike-friendly town I’ve ever been in. Drivers actually respect your right to “share the road” instead of trying to plow you off into the shoulder. I bike a mile up a very steep hill to Lowell every morning (or at least throw it on my bike rack and drive up), then ride around some forest trails during my lunch break. The Lowell campus is absolutely beautiful, sitting on the edge of a national forest, lined with flower beds, overlooking a stunning view of the volcanic peaks and the city of Flagstaff in the valley below.

Now, let’s talk about the actual work I pretend to do: My project involves analyzing “ultra deep” (really really long-exposure) images of dwarf irregular galaxies, the small, misshapen, and extremely common galaxies that populate the universe, in order to determine the extent of star formation in their extreme outer edges. Our images were observed at several wavelengths, including near- and far-ultraviolet (using an earth-orbiting satellite), radio (using the Very Large Array in New Mexico), and several optical colors (using ground-based telescopes here in Arizona).

The different wavelengths probe the star formation history at different time periods in the past. Radio emission (from the well-known 21-cm line, which is formed when the spin of the electron in a hydrogen atom flips from parallel to antiparallel with respect to the spin of the proton, dropping the electron from one hyperfine energy level to another and thereby emitting a low-energy photon) traces the distribution of cool hydrogen gas, which is where we’ll find current star formation. Ultraviolet and H-alpha emission come from hot, massive stars that burn their fuel very quickly and thus must be very young. And finally, optical emission comes primarily from cooler stars that burn their fuel more slowly and thus were formed long ago.

Now, some basic background: Stars form when a distribution of gas (somehow) compartmentalizes into individual clouds that are (somehow) sufficiently cool and (somehow) dense enough to surrender to gravitational collapse. Any successful model of star formation must be able to explain the “somehow”s. Dwarf irregular galaxies in particular are extremely useful for testing models of star formation for several reasons: First, the gas density is already very low near the centers of these galaxies, but especially in the extreme other edges (the focus of my project). Second, irregular galaxies do not benefit from “spiral density waves,” which act as the primary catalyst for star formation in spiral galaxies. (Cool fact: The beautiful “spiral arms” you see in spiral galaxies do not rotate rigidly around the core. The arms themselves rotate independently of the stars that compose them, much like waves moving forward through a traffic jam even though the individual cars barely move at all. These so-called “spiral density waves” rotate around the core of the galaxy and trigger star formation by compressing the gas. The newly born, hot blue stars do not have enough time to migrate far enough away from the arms before they explode as supernovae or otherwise burn out as white dwarfs, which explains why the spiral arms of a galaxy are typically so bright and so blue.)

The big question that my project seeks to answer is, how are stars being formed in such low-density environments and without spiral density waves to trigger formation?

Day 4 in Sunny Carbondale

Hey everyone.  I haven’t had a real opportunity to write on the blog since I got to Carbondale this past Sunday.

It has been a slow start.  There have been orientations and tours of chemistry facilities and paperwork paloozas galore over the past few days.  We have yet to obtain the equivalent of Banner ID numbers which are necessary to perform such activities as obtaining an ID card, connecting to the internet, parking legally, eating in the cafeteria, and doing laundry.  As a result, we do not have internet connectivity in the dorms, so I am writing this during my maiden visit to the library, which is very nice.

On Monday, we watched each professor who would be directing an area of research give a ten minute presentation (though ten professorial minutes is really more like nineteen earth minutes).  They were interesting, but I will admit that the day grew long.

The professor in charge of my project is out of town until Friday, so I have been operating under the supervision of a graduate student.  Yesterday, he laid out the groundwork of the project I am doing and gave me substantial reading materials.

Essentially I will be fabricating and analyzing nanowires formed from various ratios of Nickel to Iron.  There will be seven batches, 6:0, 5:1, 4:2, 3:3, 2:4, 1:5, and 0:6.  Then I will use a scanning electron microscope to study visible morphologies of the various alloys and, using energy dispersive spectroscopy with the SEM, determine the final ratio of Iron to Nickel within each sample.  If time permits, I will also perform an X-ray diffraction experiment, which I do not fully understand currently.  The most important part is certain magnetic measurements under a parallel and perpindicular magnetic field.  More details are to come.  More specific information can be had from this link, which may or may not be broken.  http://scholar.google.com/scholar?hl=en&lr=&cluster=17909959330274837858

Today I made some solutions that I will use to fabricate a 100% Nickel batch tomorrow morning.  I am also working on a presentation that I will give to our group, which will hopefully land right on ten earth minutes.

Welcome to the Atomic City!

Hello again!

Well, I finally made it to Los Alamos! The 17 hour drive wasn’t very exciting, especially driving across Kansas diagonally! I left on Saturday after having only 36 hours at home (should have been more but my car broke down coming back from KCI). I decided to knock out 10 hours the first day so that I could get to Los Alamos early afternoon. I stopped in a little town in SW Kansas called Liberal. Pretty neat town besides the moldy gas station pizza. Apparently, Dorothy Gale’s house is in Liberal - complete with a yellow brick road. They also have the Mid-America Air Museum! It has over 100 aircraft and other neat stuff. As you can tell, I got really excited when I heard that, but they had already closed for the day by the time I arrived in Liberal. I think I’ll stop by on my way back in August.

I made it to Los Alamos around 1500 logging 989 miles at an impressive 33.6 mi/gal. The student housing (University of New Mexico - Los Alamos) isn’t exactly what I expected. The way the website described it, I was under the impression that I would have a decent kitchen, bath, walk-in closet, and living area. Instead, the living area has our beds, a couch, a tiny table, and one desk (for two people!). The walk-in closet is ok, and we got two dressers. The bathroom is pretty cramped, and I would describe our ‘kitchenette’ as a ‘kitchen-in-a-closet.’ Double doors open up to reveal 3 feet of linoleum and a stove, sink and cabinets. In all, I can’t really complain - UNM just needs a better website. And besides, I’ve already met a good number of awesome people that should hopefully make my summer here somewhat exciting.

Speaking of exciting, the materials science department here at LANL disposes of their expired explosives every summer in a huge event for the student interns (about 1,200 in all). They claim that the best/easiest way to dispose of explosives is, well, to explode them. I can’t wait for that.

I had my first day of work today. I got up around 0700 and took a van provided by my program to the badge office at LANL. I got my ID card and got a chance to swipe it to get through a security checkpoint. Pretty exciting! I made the mistake of wearing a blue shirt for the photo, so now my ID card has my head floating on a blue background (the backdrop was blue). After that, I went to meet my mentor. We work in an old metal building on the edge of TA-03 (Technical Area 03). The quickest way to it from parking is via a dirt trail through some back country along the edge of a canyon. I love that the lab is set in the middle of mini mountains.

I toured our building and met some of the other employees. LANL is divided into workgroups, so there are mini work communities that do weekly lunches and dinners together. My office (yes, an office!) is not what I expected in a national laboratory. It’s just an average room. I do get my own computer with two monitors on a pretty big desk. I share the room with Misa ___. I think she’s an intern because all the permanent employees look like they are at least 30, but I’m not really sure. The people here are really laid back. They’re the mountain loving type who mainly like to have a good time while keeping their brains active and interested in the world around them.

I had to complete a couple of training excercises on the computer regarding information safety and drug abuse. I got a kick out of the information safety program because it kept referring to ‘bad guys.’ Does that make me a good guy? Other than that, the whole thing was kind of boring. After that, Josef (my mentor) explained the physics to me, showed me what I would be doing, etc. We then went to a seminar on neural network methods (my project for the summer!) that was way over my head. They guy giving the talk was from Germany. I spent the rest of the day toying with and trying to understand Python. I also started reading from a book Josef gave me on space weather. I’ll save the physics details for a little later when I get a better understanding of it and what I will specifically be doing so that I can talk about it all at once.

I got home from work around 1700 and had some rice and eggs from last night. I’m going to go play some basketball with some friends tonight. We got the basketball at Wal*Mart last night. We had to make an emergency run because a couple of guys didn’t have bed sheets. The Wal*Mart was about half an hour away in Española, but at least it was a fun drive through the curvy, cliffhanging roads.

Well, enough for now (and I wondered how everybody else was writing such long posts…). Off to get some excercise…

-Martín

if only the strong force wasn’t so strong…

Hello phyisics fans!

So I have been doing a bunch of cool stuff lately!  First off, last weekend I did my first ‘touristy’ thing and went to visit the nearby town of Marburg.  It was really awesome!  The brothers Grimm lived there for a while and there is a cool castle and stuff like that.

Here’s how it went:  Around 3:30 (I almost wrote 15:30!!) I decided I was bored and it was lame for me to just sit around.  Thus, via train, I was in Marburg at 4:30.  The train system here is amazing!  Then I wandered around for a while, eventually seeing a giant church tower.  I knew Marburg was really famous for the old section of the city, so I walked towards the tower.  It was Elizabethkirke and it was awesome.  I then, following anything old I saw, found the old city.  It was really neat.  The streets were very narrow and it was built on a hill, so the town literally had more steps in its alleys and roads then in its houses!  From here, more exploring yielded several awesome churches, a ton of cool houses, a gigantic castle, a scary dark underground tunnel that I think was left unlocked on accident, and other cool stuff.  It was a fun day, and I got home that night around 11 just in time to go out to a pub with Andreas and one of his friends.  We had some good beer and played some bad pool, so overall it was a pretty good night!

From there I had a very productive week of work.  I have continued working on the FORTRAN program and now it works!!  It is almost done, I have a few little tweeks and things, but overall I got it all working and Andreas said he was surprised at how much I had already accomplished!!  That put me in a pretty good mood…

Also, on thursday we had a presentation of some experimental physicist.  It was actually really boring because he mostly just showed us graphs, then the smart profs would ask crazy questions that he usually didn’t know the answer to.  Whenever he did say anything that could have been interesting it went way over my head.  During the presentation Andreas got out some paper and proceeded to scribble away.  After a few minuets of this, he just walked out of the presentation.  It was really loud and a bit awkward!  Later I went to his office to discover he had solved a problem with his model that I had pointed out earlier.  He was so excited that he had to try it out right then!  He told me there are two types of colloquium, one type is good because it is interesting, and the other type is good because they are so boring that you start thinking about other stuff!

Ok, so I have had one other adventure.  Yesterday me and two of the RISE girls, Jennifer (biologist from Canada) and Elise (biochemist from Alabama) went to a random town in Germany to meet one of Jenifer’s friends from high school who was randomly also in Germany.  We just chose the town that was halfway in between us, and it turned out to be an awesome place!  We climbed a large hill (or small mountain) to get to a giant statue of herkules.  Elise and I dangerously climbed over a spiked fence (that was really high up) to get on to an abandoned aqueduct.  It was super cool.  We also saw a palace and an old awesome castle.  We spent hours walking around the woods to find all these places.

After these adventures, we began to forage for food (look for a restaurant).  We were hungry and tired and wandered the streets until we found a place to eat.  The rest of the day consisted of running across a 6ish lane road, going to an awesome Grimm brothers museum, and randomly finding a festival in the town.  I bought a giant bag of candy.  Then we took a train home.  Overall, it was a good day.

Thus the point becomes, dear reader, America is lame compared to Germany because even a randomly chosen German town has a statue of herkules with 535 steps leading up to him.

Well, I’ll update when I’ve done some more physics or adventuring… until then, have fun!

-Joey

Physics Adventures in Idaho

Hey everybody!

It seems like as good of a time as any to update everyone on my project here. In the very opposite of Joey’s REU, I have been pretty much entirely experimental here in Idaho so far. My project has many stages, and I mentioned that one of the ultimate goals for my project is to help determine a characteristic signature for different fissionable material when they are shot by a linear accelerator. This way, the government can scan more of the industrial shipping crates that come into our ports everyday, helping keep our country safer.

The first aspect of this research is building a pair spectrometer. What is this/what is it used for? Well, the linear accelerator is going to shoot a beam of photons at a converter, which will convert the photon into an electron/positron pair. This converter will be placed right up next to a magnet, so the two particles will move in opposite circular trajectories. After they leave the magnet, they will fly straight into scintillation detectors. Where do I come in?

Well, they have two magnets here. There is a variable B-field electromagnet and a permanent one. The plusses of the electromagnet? It is variable. The upside of the permanent magnet? It doesn’t have a leak in it. My first task was to see if we could use the permanent magnet, whether it would bend the electron/positron pair enough to  avoid each other and the beam. Since it is a permanent magnet, there is a return yoke. So, how much energy do we need to give the electron to clear the yoke. Balance the Lorentz and centripetal forces, use the relativistic energy equation and a ton of nasty trigonometry later, we worked out that the magnet was feasible.

From there, we had to make two scintillation detectors. The was a lot of finding the right parts. A scintillation detector is just a light guide connected to a photomultiplier tube connected to a voltage module. Light hits the light guide, which guides the light (shocker, I know) to the PMT, which sends an electric impulse to an oscilloscope or whatever so we can measure whatever radiation we need. We hooked these up to about 1000V and were able to measure cosmic rays, which I found pretty cool.

For us to gain any useful information from all of this, we need to make sure that our two detectors are collecting data from an electron/positron pair from the same photon. Right now, I am working on these coincidence measurements. We have the two detectors right next to a Sodium-22 source, so we are getting hits  on our detectors more often than the cosmic rays. We send the signals to a constant fraction discriminator, which helps put the two measurements into the same shape. We send both of these signals into another box. This box is a nice “and” or “or” circuit box. It is a lot simpler and nicer than what we had to do in Electronics Lab. We are able to adjust the threshold of each detector, so we are getting hits and not just background noise, and the width of the circuit. Basically, what it takes to generate a signal and then how much time between the two different signals we give it to register them both together and thus activate the and circuit. We are talking in the nanosecond range for these things.

The last part that we need to do for this setup is send the and circuit into a counter. That way we can plateau our detectors. Basically, find the optimum energies to run them at to get the best counts. That will all be done tomorrow. Then we can get into the particle lab and try out this part of the experiment before I move on to my next task. I think that all should make pretty good sense, but feel free to ask any questions.

In other news, I have been making myself feel like a complete wimp lately. I have been running around town and among the hills here lately, and hills can really take it out of you. It has been my goal to finish this 2.3 mile run that ends at the top of this hill. I haven’t made it all the way up the final stretch without stopping yet, but there is always tomorrow. Today, another REU student/my roommate Zac and I went to a local park to participate in their Tuesday/Thursday Open Climb. A very cool guy named Peter taught us how to do figure 8 knots and belay. We both made it up our first wall, but the second proved a little too hard for us, so we both got only halfway. I never knew how much finger strength it took! We tried a third wall, and while it should have been doable, my arms were hurting so much that we called it a day. Next Tuesday, though, I am showing it who is boss.

Later tater haters,

Ian

Physik!

Hey!  This post is actually going to be about the physics im doing, so get ready!

The PhD student that I am paired with, Andreas Fedoseew, has developed a model for the structure of the nucleus that takes into account both quantum and relativistic effects.  Most of my work is writing programs in FORTRAN 90 (thank goodness its not FORTRAN 77) which carry out calculations with this model.  I will then analyze these results and he will take this into account as he modifies the model.  It is a good job, and I really like programming.

My job for the first few days was just to read and learn about the problem.  Andreas mentioned that since we are doing a purely theoretical project, I actually have to understand the Physics to be any sort of help.  I’m going to do my best here to describe the Physics, but I have yet to take quantum and it has been difficult for me to keep up with everything.  Here goes…

The traditional theory of nuclear structure is based on the nonrelativistic many-body Schrodinger equation, but this just isn’t good enough for several reasons.  Under many extreme conditions (such as particles in high density situations) it is important to take other (such as relativistic) effects into consideration.  Also it is important to consider that in quantum mech a vacuum is a dynamical object (because of pair production).  There is growing evidence that learning about these high density and high speed situations will give a lot of insight for the normal situations.  There is obviously a lot more to this… but this is a good summary I think.

Thus, the goal becomes:  Find a relativistic model for the nuclear many-body system (within quantum hadrodynamics(QHD)) where the degrees of freedom are baryons and mesons which is both Lorentz covariant and causal.  So we pretty much would like to make a theory that is like quantum electrodynamics (QED).  There is, of course, a bit of a problem here.  For those of you who remember your QED, it depends on a parameter alpha ~ 1/137.  Since alpha is small it is possible to do some sort of (Taylor i think) expansion in QED.  In QHD the coupling constants are much larger (thats why its called the strong nuclear force and the other is the weak nuclear) so the expansion does not converge.

That is a decent summary of the motivation I think.  From here I examined the Dirac Equation, and the Dirac Hole Theory.  This was a lot of crazy math, but nothing too bad.  I learned that the Dirac Equation provides a Lorentz covariant solution to free particles.  From here, using a little Lagrangian magic, we can end up with several fields which control the interaction of particles.  The particles change the fields and the fields change the particles, and we have several of each… so it is sort of a mess!

In the model we work with we use Mean Field Theory.  This theory is exactly what it sounds like, the field operators are replaced with their expectation values to make everything simpler (but still very complicated overall).  In this process we end up with what is called the effective mass(for each particle), Mstar:

Mstar = M - (coupling constant)(scaler meson field)

As it turns out, once you have Mstar you get everything else for free, chemical potential, baryon pressure, etc…  So we want to get Mstar, but when you solve for it in terms of things we get to know about, it is very very messy.  So that is my job!  Find Mstar, then find everything else.

Mstar depends on an integral which has no analytical solution.  Doesn’t sound so bad yet… but Mstar is also in this integral… which sucks!  Also we use 8 particles and each has two equations (one for Mstar and another for chem pot mu) so that is 16 linked equations which are self-consistency equations(we cant isolate the variable we care about).  To do this we use a program that is a generalization of newtons method for finding zeros (iterating over tangent lines, it is a simple idea that converges very quickly if you have a good starting point) changed to accommodate any number of dimensions which uses a Jacobian instead of a derivative.  This is the program i am optimizing.

The problem with newton’s algorithm is you need a starting point close to the zero in question.  Thus, to find solutions for high temperature we have to solve for T=0 (which is easy), then solve for a small T using the previous solution as a starting point, then work our way up to the T we care about.  This is slow and no fun.  So I have currently been programming the algorithm to decide what step size of T is the maximal possible at each point, so we dont have to do so many points just to get some high T.  it is going well so far.

So for the next few weeks i will be optimizing this program and extending it.  I will also be studying its output and looking for anything interesting.  I am glad that I am so interested in programming, because that has turned out to be my main job here!  Anyway, this is a summary of what physics is going on here.  It isnt very thorough because it is a lot of information, so feel free to ask me if you have any questions!  There is way more I could write but I feel like I have already written too much!

next post will be about my german adventures thus far, i suppose?

have fun!

-joey

Idaho- Famous Potatoes…and awesome Physics

Hey everybody!

This is Ian Noble coming to you straight from the Gem State, Idaho. I am just starting my second week in the program. I am going into my final year at Truman and figured it would be a fantastic experience to spend a summer doing an REU. At the intersection of interesting physics, fun extras, and well paying (it is a 6-way stop apparently) is the REU program at Idaho State University.

This is their first year doing an REU program, so they decided to resolve any doubts by just trying to do more. I have one of the sweetest deals when it comes to money. $4,500 plus free room and board plus full travel reimbursement. The town here, Pocatello, is absolutely stunning. It is larger than Kirksville, but it is quite dead during the summer. Luckily for anyone who likes the great outdoors (like me) this is a perfect place to spend a summer.

I had to get used to the elevation here for the first day or so, because I am definitely not used to being 4,500 feet in the air. There are many large hills and mountains plainly in view from my room. Three of us hiked up a 1,500 foot “hill” on Saturday, and I was glad that I have adjusted to the elevation. We went with a professor’s family and their horses. We even had a neighborhood dog, Abdul, who wanted to tag along. It ended up being about 5 miles when it was all said and done with, but boy was there a view. The sky is so clear here that you feel like you can see forever. We were able to see the Portneuf river, which we will be inner tubing down on July 4th.

There is no end to the beauty of nature here. We are a short trip away from Yellowstone (which they are taking us to pretty soon), 40 miles from Lava Springs (which some of us are doing a bike trip to so we can relax there before heading back), white water rafting, and so many trails to take. I took a run today that ended at the top of the school’s big hill, and that proved to be interesting. I guess I should get more into the physics that I’m doing here though, shouldn’t I?

After touring the facilities, I believe that this school has to be one of the best for nuclear and particle physics research, especially for graduate work. They have 3 linear accelerators (call linacs in the business) ranging from a “pitiful” 20 meVs to 44meVs I believe. They work closely with the Idaho Accelerator Center, which is basically on campus, to do experiments. An hour of beam time here is $2,000/hour I believe they said. They also have a mini nuclear reactor that was especially designed for use in universities to teach students about nuclear physics. It is designed so that it is impossible to go Czernobyl. They are really dedicated to this stuff and giving their students the ability to work with these machines.

I will get into the big details of what I have been working on in my next post, which may happen tomorrow after a big research project meeting we’re having, but I can summarize the concept behind it now. My project’s title is “Linear Accelerator Techniques for Homeland Security and Nonproliferation.” I finally understood what we’re doing about last Wednesday.

There are thousands of shipping crates that are sent into the United States everyday. The big ones that fit on trains and such. Only 2% of them are subjected to random safety checks, so ISU received a grant from the government to investigate if they could work out a way to have a linear accelerator to beam particles into the crates to see if there is any fissionable material in them, increasing our ability to monitor the shipments. So, we need to see if we can find a unique “signature” for different fissionable materials.

I’ll get into my work tomorrow? but until then, enjoy your summers everybody.

Ian