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1 Logo et image Alice.

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Présentation au sujet: "1 Logo et image Alice."— Transcription de la présentation:

1 1 Logo et image Alice

2 2 Infos 31 pays, 111 instituts, ~ 1000 collaborateurs Membres du groupe ALICE IPNO –Bruno Espagnon (MC resp) –Yves Le Bornec (DR) –Cynthia Hajidakis (CR) –Christophe Suire (CR) – Bruno Boyer (These) –Mercedes Lopez-Noriega (Post-doc) –Daniel Tapia Takaki (Post-doc) –Louis Bimbot (DR 50%) –Nicole Willis (jeune retraitee) –Marie-Pierre Comets (detachement ASN)

3 3 s nn = 0.9 TeV Accepted by EPJC for publication on 1 Dec last time measured at the ISR for pp Le 23 novembre : 43 minutes de collisions, 234 bons evenements enregistres Nombre moyen de particules chargees a rapidite centrale : dN/d = 3.10 ± 0.13 (stat) ± 0.22 (syst) last time measured at the ISR for pp A partir du 6 decembre, le LHC offre des faisceaux stables, evenements collectes a s nn = 0.9 TeV (tout ALICE) et des faisceaux quiet ~60000 evenements a s nn = 2.36 TeV (tracker silicium)

4 4 gs Le spectrometre a muon Distribution en moment tranverse des muons reconstruits sur un echantillon de evenements « min-bias » : les premières comparaison données-simulations donnent un accord remarquable (sans « fine- tuning ») ! asg

5 5 Collision s nn = 900 GeV s nn =900 GeV, les premiers di-muons sont observes

6 6 Historique Le premier cluster 2007 : installation et intégration –Décembre 2007 : premier cosmic run Full Alice avec la station 1 (Orsay) du spectromètre a muons : installation et intégration continuent –Deux cosmic run Full Alice –Incident LHC 2009 : intégration continue, plus de tests… –Un muon cosmic run (03/09) –cosmic run Full Alice –23 Novembre 2009 : Les premières collisions p+p at s nn = 900 GeV

7 7 LHC first beams and collisions

8 8 Historique Decembre 2009 : la premiere trace dun muon dans un collision p+p observee dans le spectrometre

9 9 Number of events ALICE : – good events at s nn = 0.9 TeV with all detectors –~60000 events at s nn = 2.36 TeV with ITS only ATLAS : –~ events at s nn = 0.9 TeV with all detectors (especially the Si- tracker) –~ events at s nn = 2.36 TeV (Si-tracker not always ?) CMS : –number of events extracted from luminosity (30% error) –but 10 (0.4) nn = 0.9 TeV (2.36) (16000) events LHCb – good events at s nn = 0.9 TeV with all detectors –~ events at s nn = 2.36 TeV (no Si-Tracker/VeLo)

10 10 s nn = 0.9 TeV ALICE first paper November 23 rd, around 16h40, the first pp collision appeared on the online display (ALIEVE) a) 284 good events recorded in 43 minutes b) Only ITS, 6 layers of silicon pixel, drift and strip detectors, is powered on. NB : ALICE is the only LHC experiment that switched on its internal tracker for the very first collisions. LHC beams were declared quiet not stable ! c) No B field d) Goal was clearly to get the first LHC paper : dn/dη with SPD tracklets (i.e. tracks made of SPD hits only )

11 11 s nn = 0.9 TeV ALICE first paper Accepted by EPJC for publication on 1 Dec last time measured at the ISR for pp The average number of charged particles created perpendicular to the beam in pp collisions at 900 GeV is: dN/d = 3.10 ± 0.13 (stat) ± 0.22 (syst) last time measured at the ISR for pp Pas assez de statistique pour la physique du spectrometre a muon good events at s nn = 0.9 TeV with all detectors ~60000 events at s nn = 2.36 TeV with ITS only Cependant ….

12 runs selected (taken during Dec. 2009). Les premiers muons

13 13 J/ψ in p+p at s nn = 900 GeV Run ; Ev650 Inter. and Muon trig m inv = 0.79 GeV/c 2 Run ; Ev170 Inter. and Muon trig m inv = 1.8 GeV/c 2 Run ; Ev650 Inter. and Muon trig m inv = 0.81 GeV/c 2 3 di-muons candidates seen in the Alice muon spectrometer… but Quite understandable : ~ 20 µb-1 of s nn = 900 GeV If : σ J/ψ ~ 1 µb, BR J/ψ µ-µ+ =6%, Acc. x Eff. spectro ~ 0.1 x 0.9 Expected nof of J/ψ = 0.1 Lets try in 2010 !

14 14 Demain, nn = 7 TeV Quelques dizaines (centaines ?) de pb-1 en collisions p+p Physique QCD, statistique a peine suffisante pour la physique electro-faible Et surtout quelques centaines de millions de collisions = 7 TeV


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