July 7

I started my day by getting my CERN computer account logged in, and tonight I will try to see if my email account works. It was more lectures this morning and afternoon, and a great slide show of the CMS assembly. What an amazing feat....not just in the science that it does, but how precise it all has to be. CMS (one of the detectors) is 15 meters tall and weighs 15,000 tonnes, and once the magnets are turned on, it compresses 20 centimeters. The compression due to the magnietic field, as well as the temperature variations, had to be taken into account in the construction, while still allowing data collection accurate to within a nanosecond (.000000001 seconds). There are 100 million channels of data that have to be collected, and collisions occur every 25 ns (.000000025 seconds). That means that particles from one collision have not yet left the detector before the next collision occurs. The data that is collected every second at the front end is equal to the amount of global data transmitted in year. to analyze the data, a 400,000 x 400,000 matrix is used.

We went to the CMS control roomm for awhile this afternoon. It was fairly quiet at that time because they weren't doing collisions, but they have resumed collisions this evening. There are monitors in the cafeteria that allow people to watch some of the information gathered at various detectors. I remember standing in the Remote Operations Center at Fermilab this time last year watching the video link to this very control room, and today i watched the video link from here back to Fermi.

We also went to the computing center here. CERN built the computer center in 1970 and put in huge mainframe computers. The "CERN unit"of computing power was defined at 4 million instructions per second, equivalent to the IBM 168 mainframe. An ordinary PC processor today is at least 2000 times more powerful. For the start of the LHC, 28,000 processors were installed in the computer center. The LHC will produce a total of 1 Gigabyte per second or more...the equivalent of 1 DVD every 5 seconds. The storage capacity is more than 15 million Gigabytes per year, or the equivalent of a 20 km high pile of CDs. In 1990, CERN established the fastest connection between Europe and the US at 1.5 Megabits per second; today it is 10 Gigabits per second. The computing grid will store 15 Petabytes a year, the equivalent of 3 million DVDs, and has a computing capacity equivalent to 100,000 processors.

Mount Blanc was very clear today. It helped in keeping my bearings as we walked around.

I missed lunch today because I came back to the room to take a nap. Note to self: no more espressos at 11 pm. Now I am off to a meeting with the Americans, and probably some more chocolate.