1. Status of ATLAS and CMS and prospects for the 2010-2011 run
Fabiola Gianotti (CERN, Physics Department)
CMS:
Multi-jet event
at √s = 2.36 TeV
(Preliminary) results from the 2009 run: a few examples …
Prospects for
More in ATLAS (M Duehrssen, A Wildauer) and CMS (S Beauceron, P Meridiani) talks this week

2. Chronology of a fantastic escalation of events:
20 November: first beams circulating in the LHC
23 November: first collisions at √s = 900 GeV
6 December: stable beams  experiments’ trackers fully on
8, 14, 16 December: few hours of collisions at √s = 2.36 TeV (the world record !)
16 December: end of first run
Max peak L in ATLAS :
~ 7 x 1026 cm-2 s-1
Recorded data samples (ATLAS) Number of events Int. luminosity (~30% uncertainty)
Total ~ 920k ~ 20 μb-1
With stable beams ~ 540k ~ 12 μb-1
At √s=2.36 TeV (flat top) ~ 34k ≈ 1 μb-1

3. 3 main messages from the first LHC run
ATLAS and CMS work extremely well:
-- few permil of non-operational channels
-- data-taking efficiency: ~85%-90%
-- detector performance is better than expected at this early stage (close to nominal)
Simulation reproduces the data very well in the (most difficult) soft regime tested so
far (years of test-beam activities, material scrutiny, tune of G4 physics lists paid off ..)
Many nice results produced very quickly (few days)  the whole experiments
work efficiently, and are not hampered by the “dynamics of the big collaborations”
 Excellent basis to do good physics soon
Silicon strip detector (SCT)

4. In the following: few examples from
huge number of (preliminary)
results (mainly detector performance)
obtained in a very short period ….

5. Resonances in the CMS tracker
K0s  π+π-
Λ  pπ-
Ξ ± Λ π± pπ- π±
Φ  K+K-
K± band
dE/dx (MeV/cm)
P(GeV/c)

6. ATLAS tracker One of the 8 jets tagged with
the secondary-vertex tagger (SV0)
(light-jet probability: 10-4 )

7. ATLAS tracker One of the 8 jets tagged with
Track transverse impact parameter wrt vertex
ATLAS tracker
One of the 8 jets tagged with
the secondary-vertex tagger (SV0)
(light-jet probability: 10-4 )
Longitudinal impact parameter wrt vertex

8. γ  e+e- conversions e- e+ ATLAS data γ conversion point
R ~ 30 cm (1st Silicon strip layer)
pT (e+) = 1.75 GeV, 11 TRT high-threshold hits
pT (e-) = 0.79 GeV, 3 TRT high-threshold hits

9. γ  e+e- conversions e- e+ ATLAS data γ conversion point
R ~ 30 cm (1st Silicon strip layer)
pT (e+) = 1.75 GeV, 11 TRT high-threshold hits
pT (e-) = 0.79 GeV, 3 TRT high-threshold hits
Beam pipe
Pixel 1
Pixel 2
Pixel 3
SCT 1

10. π0 , η γγ Photon shower shape in the first
compartment of ATLAS EM calorimeter
Note: soft photons are challenging in ATLAS:
lot of material in front of EM calorimeter
(cryostat, coil): ~ 2.5 X0 at η=0

11. π0 , η γγ  C2 segmented in ~ 4mm strips in the η-direction
Photon shower shape in the first
compartment of ATLAS EM calorimeter C1 C2 
segmented in ~ 4mm
strips in the η-direction
for γ/π0 separation

12. Electron candidates ATLAS Transition Radiation detector
Transition radiation intensity is proportional
to particle relativistic factor γ=E/mc2.
Onset for γ ~ 1000

13. Missing transverse energy
Measured over full calorimeter coverage
(3600 in φ, |η| < 5, ~ 200k cells)
Sensitive to calorimeter performance
(noise, coherent noise, dead cells,
mis-calibrations, cracks, etc.) and
backgrounds from cosmics, beams, …
Particle-Flow algorithm:
- Identify all type of particles:
Photons (ECAL only)
Charged Hadrons (Tracker only)
Electrons (ECAL+Tracker)
Neutral Hadrons (CALO only)
Muons (muon chambers + Tracker)
And then τ, π0, …
Obtain the best energy estimate
for each type of particle

14. Single hadrons and jets
|η| < 0.8, 0.5 < pT < 10 GeV
Cluster energy at EM scale
Particle-flow algorithm

15. Muons Only a few, mostly from K/π decays  soft, mostly forward
ATLAS Preliminary
Only a few,
mostly from K/π decays  soft,
mostly forward
Combined muons:
tracker +
muon spectrometer

16. pT(m1) = 3.6 GeV/c, pT(m2) = 2.6 GeV/c
m(mm)= 3.03 GeV/c2
“Global-Global muon” i.e.high quality

17. Prospects for the 2010-2011 run √s = 7 TeV Machine plan:
2010: L = ~1028  cm-2 s-1  total of pb-1
2011: L = 1 few cm-2 s-1  collect ≥ 100 pb-1 per month  total of ~ 1 fb-1
2012: shut-down
Note:
here: very preliminary estimates using fast simulations in most cases, as studies
for √s = 7 TeV have just started
a few examples for illustration only, as input to the discussion …

18. Expected number of events in ATLAS for 100 pb-1 after cuts
for some representative processes
J/ψμμ
Wμν
Zμμ
ttμν+X
inside peak
(strong cuts)

19. Two relevant examples Process 7 TeV 200 pb-1 7 TeV 1 fb-1
Z ee
tt  l+jets
Expected number of
events after cuts for
one experiment
Z  ll: with 1 fb-1 large enough sample to calibrate the detector to the “ultimate”
precision: e.g. ECAL inter-calibration ~ 0.5%, absolute E/p momentum scale
to ~ 0.1%, etc; much less needed to understand trigger and lepton efficiency
tt  l+jets: statistics with 1 fb-1 is ~ 2 times larger than one Tevatron experiment
with 10 fb-1
Note: first observation of top-quark signal in Europe with few O(10 pb-1)
Note: Tevatron expects ~ 10 fb-1 of “analyzable” luminosity by end 2011

20. Cross-section Tevatron LHC@7TeV/Tevatron LHC@14TeV/Tevatron
More in
Chris Quigg’s talk
Cross-section Tevatron
W/Z  lν, ll /0.25 nb per family ~ ~ 10
tt production pb ~ ~ 100

21. Z’ (SSM): Tevatron limit ~ 1 TeV (95% C.L)
New Physics : approximate LHC reach (one experiment) for some
benchmark scenarios (√s = 7 TeV, unless otherwise stated)
Z’ (SSM): Tevatron limit ~ 1 TeV (95% C.L)
50 pb-1 : exclusion up to ~ 1 TeV (95% C.L.)
500 pb-1 : discovery up to ~ 1.3 TeV
exclusion up to ~ 1.5 TeV
1 fb : discovery up to ~ 1.5 TeV
W’ : Tevatron limit ~ 1 TeV (95% C.L)
10 pb-1 : exclusion up to 1 TeV
100 pb-1 : discovery up to ~ 1.3 TeV
1 fb : discovery up to ~ 1.9 TeV
exclusion up to ~ 2.2 TeV
SUSY ( ) : Tevatron limit ~ 400 GeV (95% C.L)
100 pb-1 : discovery up to ~ 400 GeV
1 fb : discovery up to ~ 800 GeV
LHC will start to compete with the Tevatron in 2010, and should
take over in 2011 in most cases.

22. Higgs √s=7 TeV: H  WW, mH ~ 160 GeV (Tevatron exclusion: 163-166 GeV)
Very preliminary
estimates
Higgs √s=7 TeV: H  WW, mH ~ 160 GeV (Tevatron exclusion: GeV)
300 pb-1 per experiment : ~ 3σ sensitivity combining ATLAS and CMS (similar to Tevatron)
1 fb-1 per experiment : could exclude 145 < mH < 180 GeV
~ 4.5 σ combining ATLAS and CMS
Exclusion of the full mass range down to mH~115 GeV requires
~1.5 fb-1 per experiment at 14 TeV
Discovery for mH ~ 115 GeV requires ~ 10 fb-1 per experiment at 14 TeV
A long way to go if the Higgs is just above
the LEP2 limit.
Note: Tevatron and LHC are complementary
for mH~ 115 GeV:
-- main channels at the Tevatron:
WH, ZH with H bb
-- main channels at LHC: H γγ, qqH  ττ

23. Conclusions We are very pleased to start challenging the Tevatron
ATLAS Control Room
, day of
first LHC beams
ATLAS and CMS have successfully collected first LHC collision data
(thanks also to the exceptional performance of the LHC machine team !).
The experiments operated efficiently, from data taking at the pit, to
data processing and transfer worldwide, to fast delivery of first results.
Preliminary results indicate that the performance of the detectors, as well as the
simulation and reconstruction tools, is far better than expected at this (initial) stage.
Years of test beam activities, increasingly realistic simulations, and
commissioning with cosmics to understand and optimize the detector
performance and validate the software tools paid off …
ATLAS and CMS should be able to produce excellent physics results soon
(2010 Summer conferences).
We are very pleased to start challenging the Tevatron
in the second half of 2010 !
Many thanks to the CMS colleagues, in particular Joe Incandela, Gigi Rolandi, Guido Tonelli,