Status des ATLAS Experimentes am LHC Beschleuniger des CERN
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Status des ATLAS Experimentes
am LHC Beschleuniger des CERN
ET-Workshop
Linz, 11.4.2008
E. Kneringer
Institut für Astro- und Teilchenphysik, Universität Innsbruck
ATLAS
Kollaboration
35 Länder
164 Institutionen
1900 Wiss. Autoren
(1550 mit Doktorat)
Neue Bewerbungen:
Göttingen, Germany
Neue Interessenten:
Santiago/ Valparaíso, Chile
Bogotá, Colombia
Albany, Alberta, NIKHEF Amsterdam, Ankara, LAPP Annecy, Argonne NL, Arizona, UT Arlington, Athens, NTU Athens, Baku,
IFAE Barcelona, Belgrade, Bergen, Berkeley LBL and UC, HU Berlin, Bern, Birmingham, Bologna, Bonn, Boston, Brandeis,
Bratislava/SAS Kosice, Brookhaven NL, Buenos Aires, Bucharest, Cambridge, Carleton, Casablanca/Rabat, CERN, Chinese Cluster,
Chicago, Clermont-Ferrand, Columbia, NBI Copenhagen, Cosenza, AGH UST Cracow, IFJ PAN Cracow, DESY, Dortmund,
TU Dresden, JINR Dubna, Duke, Frascati, Freiburg, Geneva, Genoa, Giessen, Glasgow, LPSC Grenoble, Technion Haifa, Hampton,
Harvard, Heidelberg, Hiroshima, Hiroshima IT, Indiana, Innsbruck, Iowa SU, Irvine UC, Istanbul Bogazici, KEK, Kobe, Kyoto,
Kyoto UE, Lancaster, UN La Plata, Lecce, Lisbon LIP, Liverpool, Ljubljana, QMW London, RHBNC London, UC London, Lund,
UA Madrid, Mainz, Manchester, Mannheim, CPPM Marseille, Massachusetts, MIT, Melbourne, Michigan, Michigan SU, Milano,
Minsk NAS, Minsk NCPHEP, Montreal, McGill Montreal, FIAN Moscow, ITEP Moscow, MEPhI Moscow, MSU Moscow, Munich LMU,
MPI Munich, Nagasaki IAS, Nagoya, Naples, New Mexico, New York, Nijmegen, BINP Novosibirsk, Ohio SU, Okayama, Oklahoma,
Oklahoma SU, Oregon, LAL Orsay, Osaka, Oslo, Oxford, Paris VI and VII, Pavia, Pennsylvania, Pisa, Pittsburgh,
CAS Prague, CU Prague, TU Prague, IHEP Protvino, Regina, Ritsumeikan, UFRJ Rio de Janeiro, Rome I, Rome II, Rome III,
Rutherford Appleton Laboratory, DAPNIA Saclay, Santa Cruz UC, Sheffield, Shinshu, Siegen, Simon Fraser Burnaby, SLAC,
Southern Methodist Dallas, NPI Petersburg, Stockholm, KTH Stockholm, Stony Brook, Sydney, AS Taipei, Tbilisi, Tel Aviv,
Thessaloniki, Tokyo ICEPP, Tokyo MU, Toronto, TRIUMF, Tsukuba, Tufts, Udine, Uppsala, Urbana UI, Valencia, UBC Vancouver,
Victoria, Washington, Weizmann Rehovot, FH Wiener Neustadt, Wisconsin, Wuppertal, Yale, Yerevan 2
Größe der LHC Experimente
z ATLAS
¾ 35 Länder | 164 Inst. | 1900 Wiss.-Autoren (350 Stud.)
z CMS
¾ 37 Länder | 155 inst. | 2000 Physiker (400 Stud.)
z LHC-B
¾ 14 Länder | 47 Inst. | ~600 Mitglieder
z ALICE
¾ 30 Länder | 105 Inst. | > 1000 Mitglieder
3
Der Beginn von ATLAS (20 a)
z late 1980’s: R&D started
z 1992, March 3:
¾ Ascot + Eagle merge (Evian conference)
z 1992, Oct. 1:
¾ Letter of Intent (signed by Innsbruck Univ.)
z 1994, December:
¾ Technical Proposal
z 1996, February:
¾ Atlas is approved
z 1998 - 2005:
¾ Technical Design Reports
z 2003:
¾ underground cavern completed ATLAS superimposed to
the 5 floors of building 40
z 2008:
¾ spring: complete installation
4
Der ATLAS Detektor
Diameter 25 m
Barrel toroid length 26 m
End-cap end-wall chamber span 46 m
Overall weight 7000 Tons
length of cables 3000 km
# of channels ~108
5
The Underground Side C Side A(irport)
Cavern at Pit-1 for
the ATLAS Detector
Length = 55 m
Width = 32 m
Height = 35 m
“building a ship in a bottle”
6
ATLAS Caverne (Sept. 26, 2005)
Barrel Toroid
7
ATLAS Caverne (Sept. 23, 2007)
End Cap Toroid
8
Probleme
z Ja
¾ z.B. mit dem soeben gezeigten Endkappen-Toroid
9
ATLAS Endkappen Toroid-Magnet
15 m hoch, 5 m breit, CERN, 29 Mai 2007
340 Tonnen schwer
10
Atlas Puzzle Bild - da vorne drauf
kommt das Endkappen Totoid
11
Der Endkappen-Magnet-Vorfall
z Als Beispiel für die Grundvorlesung
¾ Reibung: zwischen festen Körpern
Die Physik dahinter:
Masse(Magnet) = 340 t
Annahme: P = 0.2
benötigte Zugkraft
zum Bewegen:
F = FReibung = 6.8·105 N
(= Gewicht von 68 t)
berechnete Kraft zwischen
Magnet und Kalorimeter
aufgrund der magnetischen
Anziehung bei Strom I = 15 kA:
FAnziehung | 2·105 N
(äquivalent Gewicht von 20 t)
Links: die Kühlleitung ist noch intakt. der nicht fixierte Magnet
Rechts: die beschädigte Kühlleitung. hätte sich beim Einschalten des
Der Endkappen-Magnet ist rechts noch sichtbar. Stroms nicht bewegen sollen!
12
Berichte verschiedener Leute
Marzio Nessi - ATLAS technical coordinator
During the last three weeks, we have been pursuing current ramping tests on the
End-Caps Toroid Magnets, doing them one at a time. After the first initial safety
system checks (integrity of the vacuum, power and cryogenics systems), we
started ramping up the magnet current. On the 22nd of November, the goal of the
test was to ramp up to 75% of nomimal current on ECT-C, then provoke both slow
and fast magnet dumps to check the response of the cryogenics and the
mechanical behavior of the toroids. This test is not done in a standard ATLAS
configuration but in a configuration that brings the end-cap magnet 35 cm closer
to the calorimeter end-cap than normal position. Care was taken to ensure there
was enough safety margin for this operation. Unexpectedly, at 14.7 kAmp, the
EC-Toroid moved toward the calorimeter by about 8 cm. Immediately, all activities
were stopped, and the current was released. All means were put in place to
visually inspect the Liquid Argon Calorimeter End-Cap services for possible
damage. The ATLAS safety management team brought in all experts and the fire
brigade with safety equipment just in case liquid argon would spill out.
Despite what happened, this incident confirmed that we are very well organized in case of safety problems. We were able
to put together an effective team of experts at 2:00, with a phone conference bringing together people from all over the
planet to discuss the best course of action. What amazed me was that everybody remained calm, organized and
coordinated under the supervision of our Glimos, Olga Beltramello. Nobody argued, nobody got excited but instead
everybody acted in an efficient and pro-active manner.
13
Magnet Team
Herman Ten Kate - the view from the magnets team:
From our calculations, we determined that the friction coefficient of the magnet
against the supporting rails underneath was at least 0.2. The end cap toroid
weighs 340 tonnes, which means it should not move at all if the magnetic force
of attraction is below 68 tonnes. We were testing at 15 kA, and the magnetic
force between the end cap toroid and calorimeter at that current is 20 tonnes.
We are absolutely sure of that. So, although the magnet should have been
stationary unless there was an attraction of over 68 tonnes, it in fact moved
towards the iron at a force of 20 tonnes. Clearly the friction coefficient was
much lower than we thought. But the absolute minimum friction coefficient
of a metal-to-metal contact is 0.12, according to textbooks. Even at that
coefficient, you should need 40 tonnes of attractive force to move the magnet.
To this day, we are not sure why the magnet moved at half the absolute minimum
friction coefficient. We will make a model setup using the same type of steel to try
to understand what happened. But for our magnet tests the calorimeter was in a
non-standard configuration. In the final configuration this won’t be a problem.
14
Zeitplan für die Installation von ATLAS
close 15
16
eNEWS unter http://aenews.cern.ch/
17
Wer wettet auf das Higgs!
18
Forschung:
Teilchen – Antiteilchen Übergang
Simulation
eines Ereignisses
Visualisierung der
Atlas Detektor, CERN gemessenen Daten
44 m lang, 22 hoch
25 Millionen Kollisionen
(Movie) pro Sekunde,
jede Kollision erzeugt
ein Bild von diesem Typ
Herausforderung:
Entwicklung eines effizienten Algorithmus,
der feststellen soll, ob ein Übergang
Teilchen o Antileilchen (oder umgekehrt)
stattgefunden hat, oder nicht.
Zerfallstopologie
19
Teilchen – Antiteilchen Umwandlung
z Indirekt
¾ Durch Austausch von W-Teilchen
z Übergang auch in umgekehrter Richtun
¾ Oszillation
20Bs0 o Ds– S+
z Bs Zerfall rekonstruieren
I
Wie weiß man,
ob ein Übergang
stattgefunden hat?
_
z Bs oder Bs bei Produktion und Zerfall identifizieren
¾ Produktion
Ladungsvorzeichen des Zerfallsmyons eines (nicht osz.) B-
Hadrons auf der anderen Seite: B– o P– o Bs0
¾ Zerfall
Ladungsvorzeichen des D-meson: Bs0 o Ds– 21
Ideale Oszillation
22Oszillation in einem Experiment
Bestimmung der Oszillationsfrequenz
aus diesen Daten.
Zeitauflösung ist sehr wichtig
23
Oszillation?
noch hochfrequenter
24You can also read
