Dark Matter Exists!!

There is a great post by Sean at Cosmic Variance on the new Dark Matter discovery. The post was slashdotted early Tuesday my time, so I couldn’t get at it until this evening. It’s compulsory reading for everyone.

There are just two important things to note here. Firstly, as pointed out in the article and comments, approximately 90% of the visible mass of the galaxy clusters lies in the intergalactic gas, and only about 10% comes from the galaxies themselves. The gravitational field from the galaxies that remain in the cluster after the collision is negligible. This is not where the gravity is coming from. Secondly the dark matter is only weekly interacting, both with other dark matter and also with the plasma. The Dark Matter in both clusters wouldn’t be slowed down by the collision. You would expect it to end up with the visible center of the clusters, where it would have been before the collision, which is exactly what the results show.

Of course, now we finally know for certain that this stuff exists, the next challenge is to figure out exactly what it is, and to make some of it here on earth. This is one of the most interesting problems in particle physics today, and will be one of the major goals of the Large Hadron Collider and the International Linear Collider.

Science Humour

I’m a bit behind on this one, but there are a handful of good science gags going around at the moment that I wanted to put up. The first is from Cynical-C Blog, via Cosmic Varience, on the latest US government response to the terror threat in London. They have decided to fight back by classifying an entire state of matter as a terrorist threat.


Next are a few good comics from newly discovered site xkcd, also via Cosmic Variance, which are doing the rounds.




And last but not least, another couple of classics from PhD, where Professor Smith has gone off on holiday.

Dalitz Plots

Great post on Dalitz plots over at Superweak, via Tommaso. Although these plots have been around since the 1950’s, they have become popular tools again to analyize the results coming out of the B factories. As described in the post it is possible to use Dalitz plots to measure the complex phases that occur in three-body decays from the interference behaviour of the plots. We use this method at Belle or BaBar to get information on the complex phase in the KM matrix.

Home Again

All finished. The second lecture from Tanaka-san was this morning, and most of the HEP experiment students headed back together after lunch. HEP theory and the nuclear physics students still have one more day, but we finished early because there were less of us. Actually, the organizers were talking about trying to get a lot more students, double or so, for the next year.

Just on the train back from Nagano to Nagoya at the moment. It’s a really nice trip. It heads up through the mountains in SW Nagano prefecture and then through Gifu I think.

It has been a full on five days. The lectures and talks by the other students were all really interesting. I wanted to write everything up before I forget, but I’m a bit tired and can’t spit out anything coherent at the moment. I had a really great time. Learnt lots as well, and even managed to get through the week without sleeping through any lectures, unlike the last time two years ago. I think that's actually quite an achievement, given the compulsory socialising over beers until about 3AM or 4AM every morning. Absolutely buggered though, will post a summary and a few photos over the weekend.

Thanks to Kuwabara from Tokyo for organising the high energy physics experiment session. He did a great job rounding everyone up, arranging the lectures and drinks and just generally making sure everyone had a good time. Huge success. Cheers mate.

Exploration of New Physics at the TeV scale at LHC

Today we heard from Professor Tanaka from Okayama University, who is working on the LHC detector and physics at the LHC experiment. This morning was mainly just an introduction to the experiment. He had a lot of slides on the physics, and he showed two very cool animations which show the size of the ATLAS detector, and give a basic outline of what happens in the accelerator and inside ATLAS when a collision occurs. Very very awesome. How come we don't have PR guys doing stuff like that for our experiment?

Kick Baseball

Just finished the first two days of lectures on neutrino mixing and the KamLAND experiment.

This afternoon we headed off to a local high school and borrowed their sports ground for a kick baseball tournament. About 140 students from the summer school took part. We split into two pools of four teams for a league tournament, and then a final. My team lost our second game 11-10, but won the pool on point difference. Cleaned up in the final 12-10. Everyone looks exhausted. We were playing on a standard-issue Japanese high school sand sports ground, so I took a bit of a beating when I was feilding.

Welcome party tonight. The organisers are really going out of their way to justify compulsory beers here every single day. As long as everyone is having a good time...

Summer School in Nagano

At a hotel in Kijimadaira ski resort for the annual Nuclear and Particle Physicists of Japan summer school. Last night we had a lecture on Physics at the LHC by Prof Hagiwara (KEK), who came to talk at Osaka a few months back.

We followed up the lecture with a few beers downstairs in the lecture hall, and then a few more beers upstairs in the lobby before bed. Par for the course here I think.