CERN switches to Comic Sans

In the midst of all the press about how much money can be saved by changing fonts (see e.g. http://www.cnn.com/2014/03/27/living/student-money-saving-typeface-garamond-schools/), it's nice to see CERN getting on board by switching over to Comic Sans, effective today, April 1: http://home.web.cern.ch/about/updates/2014/04/cern-switch-comic-sans

Updates, and I'm an astronomer now?

It's been a while since my last post, and a lot has changed!

First, I'm married! To the wonderful Katie Felkins, who is featured in some of the earliest posts here. We had a great time celebrating with our friends and family at the Maryland Zoo. It's hard to believe that was 8 months ago.

Second, I left high energy physics and joined the quest for Earth-like planets around other stars! For me, this is the most exciting field of science right now (and it's the fastest growing field of astronomy, so I'm not alone in thinking this). Recent advances in technology have finally made this possible on a large scale (see e.g. http://www.jpl.nasa.gov/news/news.php?release=2014-062). My data comes from Project 1640, whose goal is to blot out as much of the light from the host star as possible so that we can see the faint planets nearby. Aaaand I now have a research website! www.pha.jhu.edu/~jaguilar

Last, I am going to try focusing on shorter, less content-heavy posts to try to lower the activation barrier for writing here. We'll see how that goes.

Neutrino flavor oscillations

One of my classes this semester covers topics in experimental particle physics, and tomorrow I have to give a quick presentation about the first time neutrino flavor oscillations were experimentally confirmed. If you didn't know, one of the great physics problems of the last few decades was why, for 30 years, people measured 1/3 fewer neutrinos coming out of the Sun than they expected to see. 30 years! The problem became so infamous that it ended up being called the Solar Neutrino Problem - capital letters and a "the" in front. From 1967, when the first experiment saw this deficit, until 2001, this remained unsolved.

Basically, what was happening was that most of the experiments were sensitive only (or mostly) to one of the three types of neutrinos. It took until 2001 to collect enough heavy water to do the first observation that measured *all* types of neutrinos equally, at Sudbury Neutrino Observatory in Ontario.

But this post is not about that measurement. This post is about what you do if you have to find another way.

In June of 2001, just before SNO published its results in August, another one of these one-neutrino-only experiments (Super-Kamiokande, in Japan) released the results from its observations. While previous experiments had only confirmed the measurement of the neutrino deficit, Super-Kamiokande managed to provide evidence (albeit indirect) of the oscillations themselves by having the temerity to treat the entire Earth as nothing more than a part of its experimental apparatus (other experiments, like DAMA, do this now as part of the search for dark matter).

Why did this work? The reason electron, muon, and tau neutrinos oscillate between each other is that they are flavor eigenstates, not mass eigenstates. The flavor eigenstates are in fact built out of a superposition of mass eigenstates (the values of the matrix elements relating them is an active topic of research), and as they evolve in time each mass eigenstate picks up a time-dependent phase factor proportional to its energy. The upshot is that as the particle propagates along, the probability of it being in any particular flavor eigenstate changes. If you have a detector that can only see electron neutrinos, but two thirds of the electron neutrinos have evolved into the muon or tau neutrino state, you'll get only one-third of the neutrinos you expect!*

So what do you do if you can only measure electron neutrinos? Since the probability of a neutrino being in the electron neutrino state depends on its distance to the Sun, you just wait for the Earth to move closer or further away. You'd expect the flux of electron neutrinos to go up and down with the seasons.

And that's exactly what you get:

arxiv link, PRL link

There's something really special about this kind of magnificent simplicity.



*With some complications, but this is the simplified version.

Balloon-borne camera, part 9: Finally, success (and a final post)

I'm happy to report that after a lot of unhelpful weather got in the way, we finally have successful video! Before we get to that, I have a few more details to fill you in on. The first is that, emboldened by the success of our tiny $4 kite, we invested in what can only be described as Kite Kong, Lord of the Kites, with a whopping 9 square feet of surface area. We also bought 500 feet of 150-lb rated kite line. We went with a delta-shaped kite because they have a reputation as being easy to fly and very stable, although this parafoil kite was also an option due to a similar reputation for stability and good performance in low wind conditions. In the end, the real difference maker was that giant kites look way more awesome, so if a big parafoil kite had been available, we may have gone with that.

Anyway, with the help of one of the camp counselors, on Monday we had our first successful video-capturing flight! Here's a short excerpt from the video - as you can tell from the audio, we were having a little trouble getting altitude and needed a little help from the campers :)

Edit: Nix that for now, I'm having trouble

getting an excerpt from the video.

Will add it later.

Curiosity on Mars!

Big news lately has been that NASA put a robot the size of a car onto Mars, utilizing one of the most hare-brained landing schemes ever concocted.

So far, this has got to be one of my favorite pictures ever: a satellite orbiting mars managed to find the robot during its descent and snap a photo.

Derek Lowe, from In The Pipeline, writes:

And since we are well into the 21st century, it's only fitting and proper that we have a laser-firing, nuclear-powered robot rolling around on Mars. On to Europa, Titan, and Enceladus!

Balloon-borne camera, part 8: switching to kites and fixing poor choices

Like I told you last time, we had to make a sad decision and give up on the balloons in favor of kites. This exposed some bad practices I described in earlier posts, which will be corrected as soon as I post the corresponding correct practices!

So it was with sadness in our hearts but determination in our eyes that we went and bought our first kite, from a nearby hardware store (yeah, a hardware store). In fact, it was this kite, and it was super inexpensive. I was a little apprehensive about how much weight this little kite could lift, given our previous troubles with the balloons, but man was I proven wrong. With a little help from the high winds of an oncoming storm (note: it is a pretty dumb idea to fly a kite in a storm), we got our camera way up on the first try! No pictures, sadly, but if you look at pictures from previous posts and replace the balloons with a small Canadian flag kite, you'll get the idea.

So it worked really well, except (there's always an except)...

Olympics and the Fosbury Flop

I get really sucked into the Olympics, and I had a great time watching the high jump last night. How the heck do you walk up to a bar that you can't even reach with your fingertips, and say to yourself, "I'm gonna get my feet over that"?

I found this video from the 1968 Olympics, where the Fosbury Flop made its international debut. Since every jumper now uses this technique it was really cool to see the variety of ways people used to clear the bar before this was developed. It's even cooler to see how one guy's ingenuity allowed him to dominate the competition.

You wonder how much of a vacuum he was working in. Does anybody have any information on other people trying similar techniques at the time? There are hints of it on Wikipedia but not much solid information, and an admittedly cursory search on the web doesn't reveal much. 

The technique actually lends itself to physics analysis for its clever use of the distribution of the jumper's weight. It's explained well here (maybe with a little too much physics). I also liked reading on Wikipedia about how the eponymous Fosbury had his first inkling about the technique in high school and kept developing it until it finally worked better than the prevailing styles of the time. Technology played a role, too: I realized (obviously, in retrospect) that high jumpers didn't always have nice, cushy foam pads to land on, so athletes before the 60s had to land on their feet or risk having very, very short careers.

Edit:
I should mention that this post was inspired by the Museum's three-day event, Science at the Games (en français)! If I have somehow managed to collect some Ottawan readers, you should definitely come by. We have great sports demos going on and some really exciting guests, including Jean Labonté, a gold medalist Paralympian in sledge hockey!