OT: Zaujimavost - novy detektor zaznamenal prve castice

Daniel Valuch daniel.valuch@wanadoo.fr
Pátek Červenec 22 15:16:59 CEST 2005


Niektore casti detektorov zrazok castic su uz hotove a zacinaju sa 
postupne skusat a zahorovat.
Tu je par obrazkov zo stavby detektoru ATLAS z podzemia 
http://cdsweb.cern.ch/search.py?recid=855456 (tie rury s oranzovymi 
pasikmi su supravodive cievky).

A cely clanok:

The ATLAS barrel tile calorimeter has recorded its first events 
underground using a cosmic ray trigger, as part of the detector 
commissioning programme.

A cosmic ray muon recorded by the ATLAS barrel tile calorimeter at 
18:30, on 21 June 2005. The calorimeter has three layers and a pointing 
geometry. The light trapezoids represent the energy deposited in the 
tiles of the calorimeter depicted as a thick disk.

ATLAS has recorded its first events underground. On the evening of 21 
June, the ATLAS detector, now being installed in the underground 
experimental hall UX15, reached an important psychological milestone: 
the barrel hadronic tile calorimeter recorded the first cosmic ray 
events in the underground cavern. An estimated million cosmic muons 
enter the ATLAS cavern every 3 minutes, and the ATLAS team decided to 
make good use of some of them for the commissioning of the detector.

The purpose-built trigger system selected cosmic rays - mainly muons - 
passing ‘back-to-back' through the top and bottom of the calorimeter. 
Although only 8 of the 128 calorimeter slices (‘superdrawers') were 
included in the trigger, beautiful muon tracks were seen traversing the 
detector.

A complete ‘slice' of the ATLAS detector ran in a test beam during 2004, 
but this is the first time that events have been recorded underground.

For two weeks, experts of different disciplines from CERN and the 
experiment (cooling, high-voltage, front-end electronics, data 
acquisition, offline), led by Richard Teuscher, worked underground in 
USA15, the counting room next to the main ATLAS cavern. The goal of the 
exercise was the commissioning of hardware and software systems, 
monitoring long-term stability and checking module uniformity and 
performance. The test used final components for the whole signal chain 
up to the counting room and valuable experience was gained for the whole 
tile calorimeter system.

The project leader for the tile calorimeter, Robert Stanek, said: "The 
first picture of cosmic rays from the ATLAS pit is like a snapshot - it 
captures many years of hard work by a team from dozens of countries 
around the world."

This is just the first stage of a long ATLAS commissioning programme. 
After the completion of the installation of the barrel toroid magnet 
system, the barrel calorimeter will move to its final position in autumn 
2005 (from the temporary ‘parking' position it occupies now) and the 
final services will be connected. This autumn, a fraction of the muon 
spectrometer already installed in the pit will join the programme. The 
electromagnetic calorimeter will then be integrated after being cooled 
down in spring 2006.




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