IV Workshop Atlas-CMS

1
IV Workshop Atlas-CMS
Aspettative di ATLAS e CMS per
il pilot run 2007 e inizio 2008
triggers, rates, calibrazioni, validazione
detector, possibili misure
U.Gasparini, Univ.di Padova INFN
Padova A.Nisati, INFN Roma1
2
Sommario

• scenario di startup per LHC pilot rundel
• 2007, run di fisica del 2008 (brevi richiami)
• Rivelatori cosa ci aspettiamo di avere
• (in termini di calibrazioni, allineamenti,
• conoscenza campo magnetico, prestazioni)
• Primo commissioning su fascio
• Triggers
• Prima fisica

3
2007 LHC pilot run
Assunzioni ragionevoli
(3 settimane, ad una efficienza globale del
DAQ di 50 )
Pilot run (450 450 GeV ) luminosita L
1029 1030 cm-2s-1 Dt106s
? Ldt ? 1029?106 1035 100 nb-1
kb 43 43 156 156
ib (1010) 2 4 4 10
? (m) 11 11 11 11
intensity per beam 8.6 1011 1.7 1012 6.2 1012 1.6 1013
beam energy (MJ) .06 .12 .45 1.1
Luminosity (cm-2s-1) 2 1028 7.2 1028 2.6 1029 1.6 1030
event rate (kHz) 0.4 2.8 10.3 64
W rate (pe24h) 0.5 3 11 70
Z rate (per 24h) 0.05 0.3 1.1 7
M.Lamont Sept.06
4
LHC 2008 physics run
2008 Physics pilot run
Stage I
II
III
Hardware commissioning 7TeV Machine checkout 7TeV Beam commissioning 7TeV 43 bunch operation 75ns ops 25ns ops I Shutdown
No beam
Beam
Hardware commissioning to 7 TeV
Should look something like
Machine Checkout ? 1 month
Commissioning with beam? 2 months
Provisional
Pilot Physics ? 1 month
vedi backup slide
Nessuno puo dire oggi cosa ci sara in
aggiunta nel 2008 ( 10/100 pb-1? 1 fb-1
sembra molto ottimistico)
5
Rivelatori _at_ startup tracciatori
L Inner Detector di ATLAS
Pixels 1700 moduli, 80 milioni di celle -
misura 3 punti/traccia con accuratezza 10 mm

(115 mm nella
coordinata z) SCT 4000 moduli, 6 milioni di
canali - 4 punti/traccia con accuratezza 20 mm

(400 mm
in the z-coordinate) TRT 370k straws 36
punti con accuratezza 200 mm accuracy - C wheels
initialmente

non installate SIstemi
estremamente complessi mesi di commissioning
anche prima dei dati di fisica
6
Accuratezza in posizione, ricostruzione di
traccia con allineamento as installed

• Individual modules located on supports to 2-100?m
  in r-?
• Support structures (layers/disks/modules)
  positioned to 20-200?m
• Interferometry can monitor SCT deformation
  induced by environmental condition at 1 ?m level
• Whole ID positioned to within 500(200) ?m in X(Y)
  wrt the solenoid axis
• Possible rotation up to 0.1 mrad wrt beamline,
  about 0.1 mrad to solenoid axis
• Start system debug and alignment with cosmics and
  beam-gas interactions

• How well will tracks be found initially ?
• Use standard track finding
• Misalign all modules (SCT/pixel) by local
  installation precision
• Misalign all barrels/disks by RMS 100 ?m
• Reasonable estimate of installed precision
• Four examples different misalignments
• Study track finding efficiency wrt perfect align.
  
• 94 efficiency for local misalignments
• 40-60 efficiency for installed precision
• Tracks can still be found (with std cuts)
• Should really run with relaxed tolerances
• With 500 ?m RMS, serious degradation
• Sometimes very few tracks found
• Important to build as precisely as possible

7
Analisi di muoni cosmiciposizionamento dei
moduli SCT
Gli spostamenti relativi TRT ?SCT ottenuti dai
dati dei cosmici sono ben compatibili con
le misure del survey fatte in fase di
installazione 290 ?m vs 300 ?m Similmente
per le rotazioni 0.28 mrad vs 0.22 mrad
mm
Individual module position to less than 50 ?m
mm
8
Allineamento con i dati dalle collisioni pp
stima delle precisioni ottenibili

• Calculate r-? alignment precision from one day of
  low luminosity running (here L1033 cm-2s-1 was
  assumed)
• Use all tracks in modules, or only overlaps (few
  1)
• Results given for middle pixel barrel, and 2nd
  SCT barrel
• The same is for L1031 cm-2s-1 in the case of
  hadrons scale by 10 for muons

• Statistics to align pixels to 1-2 ?m and SCT to
  2-3 ?m using 1 day of data taking
• Limited by data recording rate rather than
  luminosity
• But systematics will also be important can make
  a start with little data

La statistica non e un problema sara piu
importante la comprensione degli effetti
sistematici
9
Rivelatori _at_ startup tracciatori in CMS
Il sistema di allineamento delle camere a mu
Pixel 720 moduli (barile) Si-Tracker 15,000
moduli
250 camere DT
L obiettivo finale dell allineamento (ovvero
essere confrontabile con la risoluzione
intrinseca)
468 Camere CSC
Strategia a due stadi
LA sfida per lallineamento con le tracce
vedi backup slide per maggiori dettagli
Nota il Pixel det. NON sara installato
nel pilot run 2007
10
Rivelatori _at_ startup Tracciatore
CMS Tracker
TIB layer4
(I)
si punta a 30 mm nel 2008 raggiungibile
(II)
11
Rivelatori_at_startup tracciamento

• 15 tracce/evento nell accettanza del
  Tracciatore, con momento medio di 0.5 GeV.
• L effetto dello scattering multiplo e
  importante
• 10 delle tracce ha pTgt2 GeV
• _at_ ECM14 TeV
• Ipotizzando di avere un trigger MB 10 Hz (10
  della bandwidth totale potrebbe essere maggiore,
  data la piccola dimensione degli eventi)
• 2 tracks/ sec
• 105 tracce/giorno

CMS Pixel, 720 modules iterative Hits Impact
parameters method
Convergenza a sxsy10mm OK
12
Rivelatori _at_ medio/lungo termine
Recente risultato (CMS ComputingSw Challenge
06)
CMS Si Tracker, 15,000 moduli 106 Z
?mm (iterative Hits Impact Parameters method)
Allineamento con le tracce dei TOB rods
Misalign.100 mm
risultato
sometime in 2008?
13
Calibrazione del rivelatore di Muoni ATLAS

• before pp data
• cosmics during commissioning (sys shift)
• cosmics in ATLAS
• Use RPC few ns accuracy
• Use track fit

14
Calibrazione del rivelatore di Muoni ATLAS
t(ns)

• before pp data
• average r-t accuracy 100?200 ?m
• cosmics in ATLAS (105/day100days ? ok)

r(mm)
15
Allineamento del rivelatore di Muoni CMS
Misure dal CMS MagnetTest Cosmic Challenge
(MTCC)
dai muoni cosmici (dati MTCC )
dal sistema di allineamento dei mu
misure dalle tracce
misure del survey
L obiettivo di una precisione 100 mm sembra
essere raggiungibile
16
CMS Muoni Cosmici in caverna
Frequenza attesa in caverna (barile)
ricostruzione muoni StandAlone, usata in MTCC

- 500 Hz nel Barile (significativamente minore
negli endcaps)
1 track events

3
2
2 tracks events
5?105 muoni /camera/giorno
(soprattutto nei sect.3-5, 9-11)
1
12
17
Pre-allineamento
Dati cosmici, nella stessa ruota
(poche ore di DAQ in caverna)
150mm
- Controllo delle misure col LASER _at_ B0 -
LASER necessario con B acceso.
18
Allineamento con le tracce del sistema dei muoni
in ATLAS introduzione

• Two alignment modes were tested in H8 2004
  setup
• Absolute alignment Reconstruct the chamber
  positions using only the optical sensor
  responses, the knowledge of their positions and
  their calibrations.
• Relative alignment Assume chamber positions to
  be known at a given time (reference geometry) and
  use sensor responses to infer the chamber
  movements with a precision of lt 20 µm since that
  time.
• Both modes are internal to the barrel or to the
  endcap muon spectrometer.
• There is no information that links the aligned
  muon system to the other detectors ID,
  calorimeters e.t.c. use tracks!
• Target achieve 30 mm accuracy on sagitta
  measurement

19
Test allineamenti nel Barile movimenti
controllati delle camere

• Complex movements (rotations displacements) of
  all barrel chambers

Relative mode Both barrel and endcap
relative alignment is known within 20 µm Absolute
mode Endcap Sagitta mean value 150
µm Barrel Sagitta mean value 350 µm
20
Allineamento con le tracce del sistema dei Muoni
in CMS

• Meno importante che in ATLAS
• esiste Link Tracker-Mu nel
• sistema hardware
• Utile cross-check
• (medio/lungo periodo)
• e.g. usando W?mn

20 giorni di presa dati _at_ L1033
N.B si assume perfetta conoscenza del campo
magnetico
Rivelatore ideale
sd100mm
2 su 4 camere disallineate in un settore di CMS
tutte le camere sono disallineate
Estimatore dello spostamento dalla
posizione ideale di una singola camera del barile
21
Disallineamnti impatto sulla fisica
Impatto su possibili scoperte iniziali
Esempio Z ?2m
CMS, L 100 pb-1 (Zh in SO(10) GUT model)
potrebbero mostrarsi presto
ideal
first data scenario

ideal
22
Campo magnetico

• Understanding magnetic field is important for
  mass scale
• W mass requires overall field integral to lt 0.05
  (10 G in the 2T Field), other physics processes
  0.1.
• Principle of the mapping
• Scanning ID volume with 48 Hall probes mounted on
  two rotating arms in ? in radial position from
  11.8 to 105.8 cm
• Hall probes calibrated to about 1G with NMR
  readings
• Four NMR probes are permanently placed at large
  radius at z0
• Mapping campaign from June 29th to August 7th
• Configuration Complete barrel, no shielding
  disk, minivan on side C
• 139000 measurements 6 points/dm3

ATLAS Solenoid
23
Campo magnetico il solenoide di ATLAS

• Field stability the NMR shows a stability of
  about 0.003 T
• The measurements have been fitted with a detailed
  model of the solenoidal field
• Typical residuals
• Br 6 G Bz 7G Bf 3 G
• Use the measurement an the field model to
  estimate the coil position in spacethe survey
  position is found within an accuracy of about 0.5
  mm
• Contributions of the iron predicted to be about
  5 of the field is confirmed by the measurements
• Goal within reach to meet the the requirement of
  a solenoidal field map with an absolute precision
  of 510-4 .
• Work in progress for further improvments

24
Misure del campo magnetico in ATLAS durante il
test del Toroide Risultati Preliminari

• Configuration only Tile, no Endcap Toroids, no
  Solenoid
• forces on the edge of the coil weaker coil
  shape different w.r.t the final layout

Coverage complete (up to DB problems)
Partial coverage A only, C only or several
chambers missing
The ATLM model
25
Most of the results here from 14000 A test
21000 Amp ! (nominal is 20500)

• Calculation done with ATLM (10kA, z 0, R 7.61
  m) and scaled using the magnet current
• current (amp) NMR(T) calculation (T) DB/B()
• 12000 0.37035 0.36936 0.26
• 13000 0.40118 0.40014 0.26
• B gradient at NMR location is lt 0.5 mT/cm
• Work in progress to correct for the probes
  position.

26
Campo magnetico CMS
Riproducibilita a livello di pochi Gauss grande
quantita di dati disponibili (misure ridondanti
) analisi in corso
CMS magnet test esempio di mappa a 3.8 T
(Oct. 06)
Br(T)
B radial component
Bz, r fissato
different r
different probes
27
Calibrazione in impulso
Le risonanze determineranno la conoscenza della
scala in impulso (? controllo mappa campo
magnetico allineamenti)
30 MeV stat.error.
CMS 20 giorni di presa dati _at_L1032 200
pb-1
2m in Barrel (hlt0.8)
1m in overlap (0.8lthlt1.2) 1m in
endcap (hgt1.2)
28
Calorimetri E.M.
ATLAS
Pb-liquid argon sampling calorimeter with
Accordion shape, covering ? lt 2.5
H ? ?? to observe signal peak on top of huge
?? background need mass resolution of 1 ?
response uniformity (i.e. total constant term of
energy resolution) ? 0.7 over ? lt 2.5
the same holds for CMS, of course
29
Calibrazione del Calorimetro

• The constant term ccL ? cLR
• The local constant term, cL
• Geometry (residual Accordion modulation)
• Mechanics (absorber gap thickness)
• Calibration (with pulse test amplitude
  uniformity, etc )
• The long-range constant term cLR (from
  module-to-module miscalibration)
• The absolute energy scale
• Use test beam measurements, cosmic ray run, pp
  collisions

30
lt gt 2.2 mm ? ? 9 ?m
EM Calorimeter, ATLAS
Da dove si parte?

1. Geometry (e.g. deviation from Accordion
   modulation) 0.3
2. Construction phase thickness of all 1536
   absorber plates (1.5m long, 0.5m wide) within
   10mm ? response uniformity lt 0.3
3. Pulse-Test and Testbeam calibration accuracy of
   each module 0.4
4. Overall local constant term 0.5-0.6.
5. Overall EM-scale 1-2. Main uncertainty from
   test beam extrapolation is probably temperature
6. Misalignment effects
7. Overall position of main elements few mm
8. Sagging/Pear Shape 1-2mm effect vs phi (barrel)

Test-beam data
Uniformity e- 245 GeV energy
0,44
Resolution e- 245 GeV energy
0,7-0,9
Comb TB 2004 0.55 over 30 cells
31
EM Cal., ATLAS
Test-beam data

• Cosmic muons
• find dead/noisy channels cabling errors compare
  with test beam data
• Check uniformity at the level of 1 accuracy
  with lt3 months of cosmics runs we can correct the
  calorimeter response variations vs h to 0.5
• Checks on drift time accuracy, at the level of
  1ns accuracy, see plot

Timing
32
Calibrazione con i primi dati

• 900 GeV data
• Huge uncertainty on luminosity. But Z,W are
  excluded as calibration probes.
• Min.Bias
• Jets
• J/psi O(103) events with Et5GeV for 1 day _at_
  1029cm-2s-1
• Inclusive electrons
• 14 TeV data
• 10 pb-1 (105s at 1032cm-2s-1) 5.103 Z,
  105 W events, inclusive electrons (also
  Upsilon)
• Overall scale in EM barrel, and EMEC OW.
• EMEC IW need e-id without tracker. Probably OK
  for Z identification. 250 events Barrel-IW per
  side
• Inter-region calibration with Z 1-1.5
• 100 pb-1 5.104 Z, 106 W
• Stat. Error on energy scale lt0.1
• Inter-region calibration with Z 0.5
• Non-linearity checks

33
ECAL calib CMS
vedi Zotto, commissioning talk
Punto di partenza misure in laboratorio(4)
test su fascio (5 SuperModuli) cosmici
Tbeam vs Cosmic data Calib.coeff.
Cosmic data
simulation
34
ECAL CMS
All inizio con i dati pp intercalibrazione
basata sulla
f-symmetry
Barrel
Endcap
107 L1 jet triggers (10 h data taking _at_ 1KHz
L1 rate)
Limite sistematico (Tracker material budget)
precisione raggiungibile 1.5 - 2.0
35
calibrazione di ECAL in CMS
Serve il Tracker allineato ben capito
Successivamente E/p (da W? en )
Endcap, 7 fb-1
Confronta con lumi richiesta da H ?gg
Barrel
precisione raggiungibile
(giusto in tempo)
NOT for 2008
Int.luminosity
36
Calibrazione di ECAL in CMS
calibrazione in situ con Z?ee (independente
dal Tracker) Precisione dell intercalibrazione
degli anelli a h constante
370 events/ring 2fb-1
37
Calorimetri Adronici

• Cell calibration
• Reference scale (starting point) for individual
  cell calibration EM scale
• LAr testbeam and calibration systems about 1
  accuracy on EM scale
• Tilecal testbeam data, Cs calibration 3
  precision on EM scale
• Cosmic muons, beam-halo muons
• Useful in many aspects
• Largon finding dead channels, cabling errors
• Compare to muon test beam data
• Trigger with Tilecal under study
• Beam-gas hadrons
• Channel mapping
• Study their properties and how to reject them

38
Minimum Bias jet events

• Monitoring detector response stability with
  1-8x106 triggers to reach 1 stability
• Cell-to-cell calibration
• Using phi-symmetry of MB triggers,
  inter-calibrate cells with equal
  dimensions/positions (2x64 cells)
• Jet calibration based on weights estimated from
  Monte Carlo studies ingredients
• Jet fragmentation modelling electromagnetic jet
  energy fraction, energy and multiplicity of
  charged hadrons, etc..
• Hadronic shower models, benchmarked in comparison
  with test beam data
• Description of dead material in simulation
  (fraction of lost energy in dead material from
  few to 15 ) studies with material distortion
  will take place in next months.
• Validation of jet adrons look to isolated
  hadrons and use E/p to understand first agreement
  between data/MC at EM scale than use hadronic
  scale and check hadron calibration.
• Example ? jets Gammajet has high QCD
  background up to about 150 GeV but reaches higher
  pT. First estimate indicates that a statistical
  error 1 in the central region up to pT 400 GeV
  with 100pb-1. Realistic trigger studies have to
  be carried out see next slide

39
Calibrazione usando i dati Gamma jet

• Validation comparing balance at reconstruction,
  MC jet and parton level gives indication on
  source of unbalances and deviation between MC and
  data
• Source of pT unbalance
• calibration biases
• contribution of UE event
• losses due to unclustered energy.
• effect of ISR contribution.
• pT balance at parton level is within lt1 ISR
  effect is small
• Cone 0.7 is correctly calibrated (red vs blue)
  and losses due to out of cone energy are
  compensated by UE (blue vs black).

pT gamma
UE
pT jet
(pT?pTparton)/2 (GeV)
40
Jets conoscenza a startup (MC)
CMS study
MC jet corrections
Starting point (test beam meas.rad.source
calib.)
Next Calib.from pp data
41
Calibrazione dei jets dai dati
CMS
QCD dijets balancing relative calibration
barrel leading jet(hlt1) against probe jet
(any h)
pTgt120 GeV, prescaled to 2.5 Hz 1 hour data
taking
Inclusive one jet QCD cross section at low pT is
a benchmark measurement 1 error on jet scale
leads to 5 error on cross section at 300 GeV
Threshold Prescale
25 GeV 10k
50 GeV 1k
90 GeV 25
170 GeV 1
300 GeV 1
400 GeV 1
ATLAS
StartUp 100 pb-1
1 x 1031 Prescales Total rate 22 Hz
42
Energia trasversa mancante
Fake Etmiss rejection Fake/badly measured muons
Shower leakage both from punchtrough and cracks
energy lost in dead material, cracks Etmiss in
direction of jet , jet in region with poor
responce,
First require detailed understanding of
instrumental Etmiss sources ? event
cleaning Beam halo muons, beam gas collisions,
cavern background, displaced vertices (use calo
cells timing, event velocity) dead/noisy/hot
cells in calorimeters
EtMiss in early dataresolution with minimum bias
and W-jets
Minimum bias Possible to test EtMiss resolution
up to ?ET300GeV
Wjets evaluate EtMiss resolution up ?ET1 TeV
(L100 pb-1)
43
EtMiss in early data in situ scale determination
with Z ? ??

Z? ?? ?lepton-hadron Expect 70000 in 100pb-1
7000 with pt(lep)_truegt15GeV
Rec ?? mass
Signal Z ? ?? Inclusive W ? e? Inclusive W ? ??
top

• Single Trigger lepton (PT15 GeV)
• Apply kinematic, Tau-Id and
• reconstructed mass cuts
• Expected in 100pb-1
• 300 evts with 20 backgd
• Possible to loosen cuts to increase statistics?
  Or more severe cuts necessary to reduce bb
  backgd?

ltgt 90 ? 16
Rec ?? mass vs EtMiss scale
3
Results still preliminar due to low background
statistics Need to have also a bb sample
Trigger-aware analysis and Cuts tuning
-3
- 10
10
44
Triggers

• Initial luminosity about L1031cm-2s-1
• Bunch spacing 75 ns
• We know which 25 ns bunch is filled-in
• Excellent opportunity to relax the timing of the
  several systems
• No real problem to identify the Bunch Crossing
• Background in the muon system is expected to be
  not a concern even in the more pessimistic
  scenarios
• Trigger time calibration not critical?relax the
  pulse width of the trigger detector signals
• Low occupancy of the muon chambers
• Data Acqusition rate 200 events/s, for 1.5 MB
  average event size it can go up to 400 MB/s.

Trigger commissioning / syncronization (local,
relative, absolute) expected to be done in the
first days of data taking (some info also
from cosmic exercise, but different time pattern
w.r.t particles fro pp interaction)
45
Sync.example CMS muon DT chambers
Syncronizing the muon passage on a chamber with
the internal clock of the chamber trigger device
Optimal phase peak -12.5 ns
Scan on internal clock phase in each DT chamber
(can be parallelized)
10 ns
9 ns
11 ns
Needs 0(105 ) prompt muons
Mean time (ns)
46
Commissioning _at_ startup muoni
?Ldt 100 nb-1
ev / 10 nb-1
2007 LHC pilot run
15000 prompt m from b/c, pTgt6 GeV
hlt2.4
Sqrt(s)900 GeV
47
Muoni Prompt 900 GeV vs 14 TeV
Pythia 6.2 ,default min.bias settings
Normalization to sinel 50 mb
?Ldt 100 nb-1
15000 prompt m from b/c, pTgt6 GeV,
h lt 2.4
100 W
Sqrt(s)900 GeV
in addition, there will be substantial number
of K/p ?m
48
Trigger menu
Object (GeV) rate(Hz) prescaling Muon 6(5)
40 6 Muon 20 14 1 Dimuons 2x6
(2x5) 3 1 e/g/t 25 20 10 e/g/t 15
20 70 2e/2g/2t 2x15 ?20 1 Jets
25,50,90,200 22 104,103,25,1 Dijets,Trijets,...
10 ? ETMiss 25,100 30 ? Minimum
Bias 20 5x104 and/or random
trigger Monitoring/Diagnostics 20 1 TOTAL RATE
220
ATLAS example, for L 1031
Trigger Commissioning The understanding of the
LVL1 trigger is one of the most crucial points
for the trigger at the startup we can run only
with the LVL1 active, HLT transparent In a
second phase insert the HLT in the Trigger system
CMS, single jets, L 1032
pre-scaling example
8 Hz
49
Segnali di fisica a Startup?
Non molto di piu che jets da QCD (includendo
b-jetse leptoni prompt che li accompagnano)
50
Misure con gli eventi di Minimum Bias
Soft physics, pile-up at higher luminosities,
calibration of experiment

• Acceptance limited in rapidity and pt
• Rapidity coverage
• Tracking covers hlt2.5
• pT problem
• Need to extrapolate by x2
• Need to understand low pt charge track
  reconstruction
• Triggering
• MBTS
• Random triggertrack trigger

v12.0.2
51
Prima fisica nel 2008
J/psi signal
Compare CDF
D.Green
7 J/y /nb-1
( harder spectrum _at_ LHC, particularly for B?
J/psiX )
CMS simulation (prelim.), both mu reconstructed
40 pb-1 ( potrebbe essere statistica totale
del physics run 2008 ?
pilot physics in Primavera sara 2 3 pb-1)
52
Esempi di prima fisica con i B
CMS Bs ? J/y f ?mm KK
ATLAS sensitivity in discovery channel B0s?
µµ-
Offline reco
HLT
Integral LHC Luminosity Signal ev. after cuts BG ev. after cuts ATLAS upper limit at 90 CL CDFD0 upper limit at 90 CL
100 pb-1 0 0.2 6.410-8 8 10-8
10 fb-1 7 20 1.210-8 8 10-8
30 fb-1 21 60 710-9 8 10-8
Bs mass
SM prediction 3.5x10-9
dDGs /Gs 20 with 1.3 fb-1
900 GeV trigger studies critical to commission
and optimise the trigger
53
Prima fisica W
Substantial numbers of W (and Z )in 2008 -
firstly, for calibration/alignment (see above) -
secondly, for doing physics (standard candles/
luminometers, precision measurements)
this is for 1fb-1, anyway (factor 10
below in 2008?)
W? en
W? mn
BUT for such purity, good knowledge of MET in
the low energy regime (ETmiss 20-40
GeV)
54
Higgs non molto nel 2008
Tuttavia, essere pronti in (almeno) alcuni
canali
e.g. H ?WW
10 fb-1
55
e naturalmente oltre lo SM
Example heavy long lived stau (LSP in GMSB
Susy) in CMS muon DT chambers
1/b
CMS simulation,1 fb-1
P (GeV/c)
56
Conclusioni

• I primi dati di collisioni pp permetteranno di
  realizzare molti
• importantissimi obiettivi
• Sotto-rivelatori
• Le iniziali calibrazioni/allineamenti
  permetteranno di realizzare
• alcuni studi di fisica
• Le calibrazioni/allineamenti miglioreranno
  notevolmente con
• le analisi dei dati iniziali rispetto alle
  conoscenze di startup
• (test-beam, cosmici, beam-halo)
• Dai sotto-rivelatori a ATLAS/CMS
• Trigger commissioning determinazione delle
  efficienze
• integrazione ed event building
• Commissioning del software offline
• Dai revalatori ATLAS/CMS ai resultati
• Alcune analisi fisiche preliminari sezioni
  durto W, Z , (top?), spettro dei muoni, dei jets
  e possibilmente nuova fisica (Z, B0s? µµ- , )

57
Backup
58
2008 pilot physics run
Sub-phase Bunches Bun. Int. beta Luminosity Time Int lumi
First Collisions 1 x 1 4 x 1010 17 m 1.6 x 1028 12 hours 0.6 nb-1
Repeat ramp - same conditions - - - - 2 days _at_ 50 1.2  nb-1
Multi-bunch at injection through ramp - collimation - - - - 2 days -
Physics 12 x 12 3 x 1010 17 m 1.1 x 1029 2 days _at_ 50 in physics 6 nb-1
Physics 43 x 43 3 x 1010 17 m 4.0 x 1029 2 days _at_ 50 in physics 30  nb-1
Commission squeeze single beam then two beams, IR1, IR5 - - - - 2 days -
Measurements squeezed - - - - 1 day -
Physics 43 x 43 3 x 1010 10 m 7 x 1029 3 days - 6 hr t.a. - 70 eff. 75 nb-1
Commission squeeze to 2m collimation etc. - - - - 3 days -
Physics 43 x 43 3 x 1010 2 m 3.4 x 1030 3 days - 6 hr t.a. - 70 eff. 0.36 pb-1
Commission 156 x 156 - - - - 1 day  
Physics 156 x 156 2 x 1010 2 m 5.5 x 1030 2 days - 6 hr t.a. - 70 eff. 0.39 pb-1
Physics 156 x 156 3 x 1010 2 m 1.2 x 1031 5 days - 5 hr t.a. - 70 eff. 2.3 pb-1
          28 days total  
59
Results of the alignment with tracks
Studies done with the H8 Testbeam setup Use 250
GeV muons
muons 250 GeV
mm
Sagitta mean value 3 µm Sagitta resolution 150
µm Statistical error on alignment 3µm
60
Validation of EM/Had scale with Jets

• QCD di-jet events. Intercalibration between
  different calo sections, may be checked using the
  back-to-back constraint pTj1 pTj2. Dijet
  balancing will be cheched first at EM and than at
  HAD scale. Allows validation of shower shape,
  detector effects, fragmentation model, jet
  calibration method.
• Statistics depends prescaled triggers or
  calibration triggers.

Inclusive one jet QCD cross section at low pT is
a Benchmark measurement. 1 error on jet scale
leads to 5 error on cross section at 300 GeV

Threshold Prescale
25 GeV 10k
50 GeV 1k
90 GeV 25
170 GeV 1
300 GeV 1
400 GeV 1
StartUp 100 pb-1
1 x 1031 Prescales Total rate 22 Hz
61
Barrel FSI
Distance measurements between grid nodes precise
to lt1 ?m
62
CMS Tracker layout
6 layers
6 layers srf35-50mm, sz500mm
220 cm
4 layers srf20mm, sz230mm
SiTracker 15400 modules
270 cm
Tracker material budget
srf10mm, sz20mm
63
Use of Beam Halo data

• Order of less than (or close to) 1 Hz/cm2 charged
  particles flux (for bunch currents close to the
  nominal one) is expected
• Very useful to commission the EndCap muon
  trigger, in particular the Level-1
• Reconstruct tracks in the forward Muon
  Spectrometer and check the tracking and trigger
  chambers alignment
• Continue studies of track reconstruction in the
  forward Inner Detector and system alignment
• measure p0 in EM calo and check shower shapes
• Understand the beam-halo events as potential
  background to large Missing ET events (event
  selection)

64
Beam halo muons

• Beam halo muons are machine induced secondary
  particles and cross the
• detector almost horizontally. Thus leaving
  essentially signals in the endcaps.

Muons
Hadrons
Muons
Plots based on LHC Project Note 324 (2003) LHC
optic 6.4 ? in IP1 0.5 m Beam current 0.54 A
Rather flat rate
R in cm
R in cm
E in GeV
Note Results are strongly dependent on machine
parameter settings. These settings are not
anymore more fully up-to-date. Improved machine
simulations are in preparation!
Substantial Expected Rates for E?gt100
GeV However, still significant uncertainties in
simulations but probably good enough for a first
impression
NHIT?1 Hz
CMS tot 1000
Muon 800
Calo. 800
tracker 200
?Very interesting for several commissioning effort
s of the endcap regions
65
Triggering Beam halo muons in CMS
Tracker Rlt110cm
Beam Halo Muon traverse Tracker volume Rlt110cm.
66
Calibrazione dei jets dai dati
Absolute calibrations
Tools

• - g jets ( ? absolute scale)
• Tower-to-tower response to isolated W? mn
• W mass fitting in tt
• MET
• - Zjet

Next slide
increasing lumi
67
Calibrazione dei jets dai dati gjet
Statistics NOT an issue Systematics
initial state QCD rad.
jet backg. to photons
kjetpTjet/pTg
the observable quantity
CMS
using MC true in jet algo
isolated g ETisol lt 5 GeV
Syst. error
Threshold ETtowergt0.5GeV
68

• DA AGGIUNGERE