LHCb on track
On 7 and 8 June 2006, the last large component of the LHCb experiment was lowered into the cavern. This 10-tonne, 18-metre long metal structure known as 'the bridge' will support the LHCb tracking system.
The LHCb is a bit like a large millefeuille pastry but this is where the culinary comparisons end as positioning the various layers of this enormous detector is no piece of cake. The task is made even harder by the lack of space in the LHCb cavern, which was once the home of the Delphi experiment at LEP and now also houses the cryogenic systems for the accelerator. On 7 and 8 June, lowering the "bridge", a 10-tonne, 18-metre-long metal structure, down the shaft was no trivial matter. In the cavern, where it had to be turned and moved into its final position, there were only a few centimetres to spare, 'It was the last large component', explains Rolf Lindner, who is coordinating the installation of LHCb. 'The remaining parts to be lowered into the cavern are much smaller and weigh less than a tonne'.
The bridge is a huge component made of stainless steel, a material which is only slightly magnetic and was chosen to avoid creating interference. It is fitted with rails onto which the three stations of the silicon inner tracker and the three stations of the outer tracker consisting of 5 millimetres of straw tubes will be slid. These components, which are designed to reconstruct the trajectories of the particles, will be sandwiched between the RICH2 detector, which will identify the charged particles, and the magnet that will bend their trajectory. Since the bridge was installed, the teams have been checking its mechanical behaviour and making sure that the frames that will support the tracker modules are being integrated with the required precision. Towards the end of the year, all of the modules will have been installed on their respective frames and the trackers will be in place under the bridge so that the first tests to run all the detectors together can go ahead in December.
There is still much to be accomplished between now and then. Two teams are working in shifts to complete the installation of the LHCb components, one from 6.00 a.m. till 4.00Â p.m. and the other from 9.00 a.m. to 7.00 p.m. This makes it possible for them to move components in the morning and in the evening without getting in each other's way. The lack of space is the biggest challenge for the installation of the experiment. The various detector layers are the responsibility of different teams and, as they are very close together, this requires some juggling of work schedules.
In spite of these difficulties, Rolf Lindner is confident. LHCb is on schedule and all of its systems will be fully installed and ready for the final tests by May 2007, so that the cavern can be closed in August. In the meantime, the next milestone will be when LHCb receives its vital beryllium vacuum chambers (see Bulletin No. 05/2005).
