Kiwi Particle Physicist

September 28, 2006

Nobel Prize Speculation

The winners of the Nobel Prize in Physics will be announced a week from today, on Tuesday October 3. Peter Woit has a post about it, with people discussing their favourites it the comments. The leading contenders at the moment seem to be:

1) The COBE and WMAP teams, for their discovery of anisotropies in the cosmic microwave background, and
2) Michael Berry and Yakir Aharonov, for theoretical condensed matter physics.

Personally I’d like to see it go to Kobayashi and Maskawa for their theory of CP Violation. As of this summer the unitary triangle is looking very consistent, and their names have come up before, so it wouldn’t be too unexpected.

I should point out though that there is a fairly strong bias towards High Energy Physics and cosmology here. Over the last few years more than half of the Nobel Prizes have gone to condensed matter physics, and the prize could of course come from there this year as well. Look forward to seeing who wins.

September 21, 2006

Belle Back for Autumn

The KEKB accelerator was fired up again after the summer shutdown at 09:00 on September 19. There were problems with the injection system of the HER (high energy ring), which meant we couldn’t get enough electrons stored in the rings for collision for the first 24 hours or so, although it looks a bit better now. The LER (low energy ring, positron) beam seems to be working normally. Collisions started at about 19:30 last night, and we started taking data at 22:43 after a few hours of tuning.

The graph below shows the recent performance of the KEKB accelerator. The horizontal axis represents time and shows the last 24 hours. The yellow line in the third graph from the top shows the instantaneous luminosity (collisions per second), and is currently about 8.145 /nb/s, compared to our world record of 16.517 /nb/s. It will hopefully climb fairly quickly over the next couple of days. The dark green line (right axis) in the same graph shows the integrated luminosity -- which corresponds to the total amount of data recorded -- for the runs so far. You can see the text "Collision Tuning" at the top of the graph, which indicates that the accelerator experts are still trying to figure out the best way to get the two beams to collide with each other. Things don't always work exactly the same after a long shutdown as they did before, so it takes a while to make sure both beams are stable and on target so that we can get as much data as possible out of the machine.

I'm amazed at how easily they have managed to bring everything back online after having people down there fiddling with it for the last two months or so. I have shifts in another three weeks or so, so hopefully it will all be back to normal by then.

September 20, 2006

Soccer, Game 2

Had the second game of the tournament today at lunchtime. We had another 0-0 draw, this time against Zaimu (Finance Department.) Overall I thought we played pretty well -- better than last time anyway. The main problem was that we were playing seven aside on less than half a normal field, which makes it pretty crowded, and we didn’t have enough room to move the ball around. In addition to that, none of our long passes were hitting their targets. It was the same for the other team as well. We pretty much just slugged it out in the middle of the pitch for the whole 30 minutes.

We have two games to go, and we probably need to win both of them to have a chance of making it to the next round.

I will head back to Osaka this evening. Should be there for the next three weeks or so until I have a set of experimental shifts again.

Iwabuchi takes a kick in.

Discussion after the game.

September 17, 2006

Wire Chambers

Belle Plus is off to a good start. Yesterday we had an introductory lecture from Abe san, and then Haba san gave us a tour of the KEKB tunnel and the Belle detector. Afterwards we had dinner and a welcome party, where I was in charge of running a group trivia session, and then we all headed back to the dorm for (non-alcoholic) drinks. All the students seemed really interested, but they are different ages and at different levels so I think we might have a bit of a challenge ahead of us. I spent half the evening explaining how to calculate velocity, distance and time to a first year student, and then spent an hour or two explaining how the weak interaction works and what Feynman diagrams mean to a third year. It’s a bit difficult to entertain everyone at once.

This morning Uno san helped us make wire chambers. A wire chamber is a simple particle detector made out of a tube filled with gas, and a wire with high voltage applied passing through it. When a charged particle (a cosmic ray, for example) passes through the tube, it kicks electrons out of the gas. These are attracted to the nearby wire because the high voltage in the wire creates a strong electric field, and by counting the number of electrons passing through the wire you can calculate the energy of the original cosmic ray.

The students started off with a square pipe and endplates, which had openings for the high voltage supply and the gas input. They paired off to assemble the whole thing. Afterwards we got all the wire chambers together and tested them. They all seemed to be working, but unfortunately we ran out of time. I think Uno san wanted to wire them up in coincidence and count cosmic rays, or measure their angular distribution. It was good fun though. It’s always a good experience when you get to build stuff yourself and check that it works.

September 16, 2006

Fun Few Weeks

Everything’s been going great recently. I’ve had a very busy couple of weeks, with a few days R&R thrown in as well. I haven’t posted anything in ages, but I’ve got a mountain of drafts sitting almost ready to go.

I popped back to KEK late August for a few meetings. We had the whole Osaka group up here, including the new first-year grad students, for the first time. It was supposed to be a group study session, but Hara san (our advisor at Osaka) found a rock climbing gym, so we all headed out for a day of bouldering, and then stopped for steak and beers on the way back.

The next day was the annual KEK open house, so we took the chance to go and have a look at all the other experiments here we never normally get the chance to see.

After finishing with the last summer school in Nagano last month, I was asked to help with organizing the summer school for Osaka University. This is a three-day/two-night trip to somewhere nearby for the HEP theory/experiment groups, nuclear physics theory/experiment groups, cosmology, astrophysics, and space science theory/experiment groups, and the experimental laser fusion group. I popped back to Kyoto/Osaka from the lab here earlier this month to help with organizing the program and to attend. Good fun.

Over the last week we had a Belle Analysis Meeting (BAM), which are normally held every couple of months or so, and where everyone presents their results to get approval from the rest of the experiment before publication. After that, on Wednesday and Thursday, there was the conference on B Physics and New Measurements (BNM), and I got roped into helping with odd jobs there as well, including helping the visitors set up their wireless connections, and running around with the mikes during the question sessions at the end of each talk.

The KEK soccer tournament started a couple of days ago, and the Belle Football Club drew our first game against the Shisetsu (Plant and Facilities Department) team. They were supposed to be one of the stronger competitors, so it wasn’t a bad start to the tournament. Got up early this morning and went for a run as well, for the first time in ages. I did two laps around the accelerator (6.6km) in 28’30”, which is not too far off a new PB.

Anyway, back to work. From today we (actually Nara Women’s University) are hosting Belle Plus at KEK. It is a program aimed at high school students, where they will have the chance to come up here for a long weekend and see what we do, and get the chance to play around with the detector and software a little bit. I am the class supervisor for the software group, and am basically in charge of showing them around, answering their questions, and just generally getting them organized for the next three days. We start in an hour or so, but the kids are piling into the cafeteria for lunch as I type. When this is finished I have the second game of the soccer tournament on Wednesday, and then I’ll head back to Osaka for a few months concentrated effort on the analysis. I have been working on it for three months already and am making only very slow progress. Apart from two weeks worth of shifts after the detector starts up for the Autumn run, I should be pretty much focused on getting it finished.

Updates from the last few weeks will appear gradually over the next few days as I get a bit more free time.

September 14, 2006

Could a black hole at the LHC end the world?

There is an article at the Sydney Morning Herald that talks about the possibility of a Black Hole being made at the LHC and destroying the Earth. This issue seems to pop up quite often when starting up a new accelerator. Needless to say, there's nothing to worry about.

They asked "What do you think? Is it worth playing the odds?" and posted everyone's responses on the site. Here's the comment I left.

It's absolutely worth it.

As pointed out in the list of threats in the Wikipedia article linked above, the particle collisions that will be produced at the LHC are similar to those that occur naturally in our atmosphere anyway. Cosmic rays (mainly protons) with much higher energy than those to be used in the LHC experiment collide with protons in the atmosphere, and have done so since the beginning of our solar system. The collision energy of a single proton at the LHC is equivalent to 10^5 TeV, whereas cosmic rays have been observed with energies as high as 10^8 TeV, about 1000 times higher.

If there was any danger of a stable black hole or some other dangerous matter forming in collisions at these energies, then we would have been wiped out already.

I can't wait to see the first results from this machine when it gets up and running in a year or so. It will hopefully tell us a lot more about why our universe is here, and deliver a few suprises along the way.

As someone else pointed out though, it might just be a cunning way for the experiment to get a bit of publicity. Works well for the experiment, and gives the media something else that they can hype up. Everyone's a winner.