iv workshop atlas-cms

U.Gasparini/A.Nisati

Atlas-CMS workshop, Bologna 24/11/06 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 PadovaA.Nisati, INFN Roma1



Sommario

scenario di startup per LHC: “pilot run”del 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



2007 LHC pilot run

“Pilot run” (450 + 450 GeV ): luminosita’: L= 1029 – 1030 cm-2s-1

t~106s Ldt 1029106= 1035 =100 nb-1

Assunzioni “ragionevoli”…:

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

(~3 “settimane”, ad una efficienza “globale” del DAQ di ~ 50% )



LHC :2008 physics run

Should look something like…Hardware commissioning to 7

TeV

Machine Checkout 1 month

Commissioning with beam 2 months

Pilot Physics 1 month Pro

visional

Stage I II III

No beam Beam

Hardware commissioning

7TeV

Machine checkout

7TeV

Beam commissioning

7TeV

43 bunch operation

75ns ops 25ns ops I Shutdown

2008 :Physics pilot run

Nessuno puo’ dire **oggi**cosa ci sara’ in aggiunta nel 2008( 10/100 pb-1? 1 fb-1 sembra **molto** ottimistico…)

[vedi backup slide]



Rivelatori @ startup: tracciatori

L’ Inner Detector di ATLAS

Pixels: 1700 moduli, 80 milioni di celle - misura 3 punti/traccia con accuratezza 10 m (115 m nella coordinata z) SCT: 4000 moduli, 6 milioni di canali - 4 punti/traccia con accuratezza 20 m (400 m in the z-coordinate) TRT: 370k straws – 36 punti con accuratezza 200 m accuracy - C wheels initialmente non installate SIstemi estremamente complessi – mesi di commissioning anche prima dei dati di fisica…



Accuratezza in posizione, ricostruzione di traccia con allineamento “as installed”

Individual modules located on supports to 2-100m in r- Support structures (layers/disks/modules) positioned to 20-200m

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



Analisi di muoni cosmici:posizionamento dei moduli SCT

Individual module position to less than 50 m

mm

mm

Gli spostamenti relativi TRT ↔SCTottenuti dai dati dei cosmicisono ben compatibili con lemisure del survey fatte in fase di installazione:

290 m vs 300 m

Similmente per le rotazioni:

0.28 mrad vs 0.22 mrad



Allineamento con i dati dalle collisioni pp : stima delle precisioni ottenibili

Calculate r- alignment precision from one day of low luminosity running (here L=1033 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 L=1031 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



Rivelatori @ startup: tracciatori in CMS

468Camere CSC

250 camereDT

Pixel: 720 moduli (barile)Si-Tracker:~15,000 moduli

L’ obiettivo finale dell’ allineamento(ovvero: essere confrontabile con la risoluzione intrinseca)

Il sistema di allineamento delle camere a mu :

Strategia a due stadi…[ LA sfida per l’allineamento con le tracce…]

Nota: il Pixel det. NON sara’ installato nel pilot run 2007

[vedi backupslide permaggiori dettagli]



Rivelatori @ startup: Tracciatore

(I)

(II)

si punta a ~ 30 m nel 2008;raggiungibile…

CMS Tracker:

“TIB” layer4



Rivelatori@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 pT>2 GeV

@ ECM=14 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 x=y~10m OK



Rivelatori @ medio/lungo termineRecente risultato (CMS Computing&Sw Challenge ’06):

Allineamento con le tracce dei TOB rods:CMS Si Tracker, ~15,000 moduli

106 Z (iterative Hits & Impact Parameters method)

Misalign.~100 m

risultato

sometime in 2008?



Calibrazione del rivelatore di Muoni: ATLAS

MDT calibration : tMDT calibration : too + r-t relation + r-t relation

ultimate accuracy in to : 0.4 ns

needs ~ 104 hits/tube O (109) -triggers

(geometry + included)

before pp data :• cosmics during commissioning

(sys shift)• cosmics in ATLAS

• Use RPC: few ns accuracy• Use track fit

t(ns)

dn/

dt

to

1040.4 ns

(to)

(ns)

n



MDT calibration : tMDT calibration : too + r-t relation + r-t relation

ultimate accuracy in r/t : ~10m

needs ~ 2.5×104 good /chamber

O (108) -triggers

(geometry + included)

+ temperature+B-field corrections

+ a lot of computing.

t(ns)

r(mm)

before pp data :• average r-t; accuracy:

100200 m• cosmics in ATLAS

(105/day×100days ok)

Calibrazione del rivelatore di Muoni: ATLAS



Allineamento del rivelatore di Muoni: CMS

Misure dal CMS MagnetTest –Cosmic Challenge “(MTCC”):

dal sistema diallineamento dei mu

dai muoni cosmici (dati MTCC )

L’ obiettivo di una precisione ~100 m sembra essere raggiungibile…

misure del “survey”

misuredalletracce



CMS: Muoni Cosmici in caverna

Frequenza attesa in caverna (barile) [ ricostruzione muoni “StandAlone”, usata in MTCC ]

- ~500 Hz nel Barile (significativamente minore negli endcaps)

“2 tracks”events

1 trackevents

~5105 muoni /camera/giorno (soprattutto nei sect.3-5, 9-11)

1

32

12

…



“Pre-allineamento “

Dati cosmici,nella stessa “ruota”

(~poche ore di DAQ in caverna)

~150m

- Controllo delle misure col LASER @ B=0;- LASER necessario con B acceso….



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 < 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 m accuracy on sagitta measurement



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 µmBarrel: Sagitta mean value ~350 µm



Allineamento con le tracce del sistema dei Muoni in CMS

- Meno importante che in ATLAS- esiste Link Tracker-Mu nel sistema hardwareUtile “cross-check”:(medio/lungo periodo)e.g. usando W

Estimatore dello spostamento dalla posizioneideale di una singola camera del barile

~20 giorni di presa dati @ L=1033

Rivelatore ideale

tutte le camere sono disallineate

2 su 4 cameredisallineate in un settore di CMS

[N.B: si assume perfetta conoscenza del campo magnetico…]

~100m



Disallineamnti: impatto sulla fisica

Impatto su possibili scoperte ‘iniziali’: Esempio: Z’ 2CMS, L= 100 pb-1 (Z in SO(10) GUT model)

“ideal” “first data”scenario

potrebberomostrarsipresto…

+ideal



Campo magnetico Understanding magnetic field is important

for mass scale W mass requires overall field integral to

< 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 z=0; 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



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 space:the 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 5·10-4 .

• Work in progress for further improvments



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



• 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 < 0.5 mT/cm

• Work in progress to correct for the probes position.

21000 Amp ! (nominal is 20500)Most of the results here from 14000 A test



Campo magnetico: CMS

CMS magnet test:esempio di mappa a 3.8 T (Oct. ‘06)

B radial component

Br(T)

Bz, r fissato

different r

different probes

Riproducibilita’ a livello di pochi Gauss;grande quantita’ di dati disponibili (misure ridondanti …); analisi in corso



Calibrazione in impulso:

Le risonanze determineranno la conoscenza della scala in impulso

( controllo mappa campo magnetico & allineamenti)

CMS:20 giorni di presa dati @L=1032

[≡200 pb-1]

2 in Barrel(||<0.8)

1 in “overlap” (0.8<||<1.2)1 in endcap(||>1.2)

~30 MeV stat.error.



Calorimetri E.M.

Pb-liquid argon sampling calorimeterwith Accordion shape, covering || < 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 || < 2.5

ATLAS

the same holds for CMS, of course…



The constant term c=cL cLR; The local constant term, cL:

1. Geometry (residual Accordion modulation)2. Mechanics (absorber & gap thickness)3. 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

Calibrazione del Calorimetro



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 ~ 10m response uniformity <~ 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:1. Overall position of main

elements: ~few mm2. Sagging/Pear Shape: ~1-2mm

effect vs phi (barrel)

< > = 2.2 mm 9 m

Test-beam data

Resolution: e- 245 GeV energy

Uniformity: e- 245 GeV energy

0,7-0,9%

0,44%

Comb TB 2004:

0.55 % over ~30 cells

EM Calorimeter, ATLAS

Da dove si parte?



Cosmic muons: • find dead/noisy channels; cabling

errors; compare with test beam data;• Check uniformity at the level of 1%

accuracy; with <3 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

S() / (noise) 7

Muon signal in barrel ECAL

Test-beam data

Test-beam data

Timing

EM Cal., ATLAS



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 Et~5GeV for 1 day @ 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 <0.1% Inter-region calibration with Z ~0.5% Non-linearity checks



ECAL calib: CMS

Cosmic data simulation

Tbeam vs Cosmic data Calib.coeff.

Punto di partenza: misure in laboratorio(~4%)+ test su fascio (5 SuperModuli) + cosmici…

[vedi Zotto, commissioning talk]



ECAL : CMS

All’ inizio con i dati pp: intercalibrazione basata sulla “symmetry”

~107 L1 jet triggers(10 h data taking @ 1KHz L1 rate)

Limite sistematico(Trackermaterial budget…)

Barrel Endcap

precisione raggiungibile: ~ 1.5 - 2.0 %



calibrazione di ECAL in CMS

Successivamente : E/p (da W e )

Int.luminosity

precisioneraggiungibile

Barrel

Endcap, 7 fb-1

Serve il Tracker allineato& ben capito…

Confronta con lumi richiesta da H

(giusto intempo…)

NOT for2008…



Calibrazione di ECAL in CMS

+ calibrazione “in situ” con Zee (independente dal Tracker):

Precisione dell’ intercalibrazione degli anelli a constante

370 events/ring : ~ 2fb-1



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…



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/pE/p to understand first agreement between data/MC at EM scale than use hadronic scale and check hadron calibration.

Example : + jets Gamma+jet 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



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:

1. calibration biases

2. contribution of UE event

3. losses due to unclustered energy.

4. effect of ISR contribution.

pT balance at parton level is within <1% 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).

(pTγ+pTparton)/2 (GeV)(pTγ+pTparton)/2 (GeV)

pT

ba

lan

ce5%

Parton levelParticle level Cone 0.7Reconstruction level Cone 0.7

pT jet

pT gamma

UE



Jets: conoscenza a “startup” (MC…)

CMS study:

MC jet corrections:

Starting point …(+test beam meas.+rad.source calib….)

Next:Calib.from pp data



Calibrazione dei jets dai dati

QCD dijets balancing:relative calibration

“barrel leading jet”(||<1)against ‘probe’ jet (any ||)

pT>120 GeV,prescaled to 2.5 Hz ~1 hour data taking

1 x 1031 Prescales

Total rate 22 Hz

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 StartUp:

100 pb-1

Threshold Prescale

25 GeV 10k

50 GeV 1k

90 GeV 25

170 GeV 1

300 GeV 1

400 GeV 1

CMS

ATLAS



Energia trasversa mancante: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

Fake Etmiss rejection Fake/badly measured muons Shower leakage both from punchtrough and cracks energy lost in dead material, cracksEtmiss in direction of jet , jet in region with poor responce,…

EtMiss in early data:resolution with minimum bias and W-jets

Minimum bias: Possible to test EtMiss resolution up to ET=300GeV

W+jets: evaluate EtMiss resolution up ET=1 TeV (L=100 pb-1)



Single Trigger lepton (PT=15 GeV)

Apply kinematic, Tau-Id andreconstructed 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?

<> ~ 90 ~ 16

Signal Z Inclusive W e Inclusive W top

Z lepton-hadron

Expect 70000 in 100pb-1 7000 with pt(lep)_true>15GeV

EtMiss in early data: in situ scale determination with Z

Rec mass

Rec mass vs EtMiss scale

- 10 % +10 %

+3%

-3%Results still preliminar due to low background statistics

Need to have also a bb sample Trigger-aware analysis and Cuts tuning



Triggers Initial luminosity: about L=1031cm-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 criticalrelax 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)



Sync.example: CMS muon DT chambers

Scan on internal clock phase ineach DT chamber (can be parallelized…)

Optimal phase:peak -12.5 ns

9 ns 11 ns…10 ns

Mean time (ns)

Syncronizing the muon passage on a chamber with the internal clockof the chamber trigger device:

Needs 0(105 ) “prompt” muons



Commissioning @ startup: muoni # ev / 10 nb-1

2007 LHC pilot run

.0ˆ Tp

.10ˆ Tp

Ldt = 100 nb-1

Sqrt(s)=900 GeV

~ 15000 prompt from b/c, pT>6 GeV ||<2.4



Muoni “Prompt” : 900 GeV vs 14 TeV

Pythia 6.2 ,‘default’ min.bias settings

Ldt ~ 100 nb-1

.0ˆ Tp

.10ˆ Tp

Sqrt(s)=900 GeV

.0ˆ Tp

.20ˆ Tp

.10ˆ Tp

~ 50000 prompt from b/c, pT>6 GeV

W

Sqrt(s)= 14 TeV

Ldt ~ 10 nb-1

~ 15000 prompt from b/c, pT>6 GeV, || < 2.4

Normalization toinel= 50 mb

~ 100 W

[ in addition, there will be substantial number of K/



Trigger menuObject (GeV) rate(Hz) prescaling

Muon 6(5) 40 6Muon 20 14 1Dimuons 2x6 (2x5) 3 1e/ 25 20 10e/ 15 20 702e/2/2 2x15 20 1Jets: 25,50,90,200 22 104,103,25,1Dijets,Trijets,... 10 ?ETMiss 25,100 30 ?Minimum Bias 20 5x104

and/or random triggerMonitoring/Diagnostics 20 1TOTAL RATE ~220

ATLAS example,for L= 1031 :

CMS, single jets, L= 1032

~8 Hz

pre-scaling example:

Trigger CommissioningThe understanding of the LVL1 trigger is one of the most crucial points for the trigger at the startupwe can run only with the LVL1 “active”, HLT “transparent”In a second phase insert the HLT in the Trigger system



Segnali di fisica a “Startup”?

Non molto di piu’ che jets da QCD(includendo b-jets…e leptoni ‘prompt’ che li accompagnano…)



Misure con gli eventi di Minimum Bias

Acceptance limited in rapidity and pt

Rapidity coverage Tracking covers ||<2.5

pT problem Need to extrapolate by ~x2 Need to understand low pt

charge track reconstruction• Triggering

MBTS Random trigger+track trigger

v12.0.2

Soft physics, pile-up at higher luminosities, calibration of experiment



Prima fisica nel 2008

~40 pb-1 ( potrebbe essere ~ statistica totale del “physics run” 2008 ?; “pilot physics” in Primavera sara’ 2 – 3 pb-1)

D.Green

Compare CDF:

~7 J/ /nb-1

J/psi signal:

( harder spectrum @ LHC, particularly for B J/psiX )

CMS simulation(prelim.), both mureconstructed



Esempi di prima fisica con i B

Integral LHC

Luminosity

Signal ev. after

cuts

BG ev. after cuts

ATLAS upper limit at

90% CL

CDF&D0 upper

limit at

90% CL

100 pb-1 ~ 0 ~ 0.2 6.4×10-8

8 ×10-8

10 fb-1 ~ 7 ~ 20 1.2×10-8

30 fb-1 ~ 21 ~ 60 7×10-9

SM prediction 3.5x10-9

900 GeV trigger studies critical to commission and optimise the trigger

ss ~20% with 1.3 fb-1

Bs mass

HLT Offline reco

CMS: Bs J/ ATLAS : sensitivity in discovery channel B0

s→ µ+µ-



Prima fisica: W

W e W

BUT: for such purity, good knowledge of MET in the low energy regime (ET

miss ~20-40 GeV)…

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?) ]



Higgs: non molto nel 2008…

Tuttavia, essere pronti in (almeno) alcuni canali:

e.g. H WW

10 fb-1



…e naturalmente oltre lo SM

Example: heavy long lived stau (LSP in GMSB Susy) in CMS muon DT chambers

CMS simulation,1 fb-11/

P (GeV/c)



Conclusioni

I primi dati di collisioni pp permetteranno di realizzare moltiimportantissimi 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 d’urto W, Z , (top?),

spettro dei muoni, dei jets e possibilmente nuova fisica (Z’, B0

s→ µ+µ- , …)



Backup



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 @ 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 @ 50% in physics 6 nb-1

Physics 43 x 43 3 x 1010 17 m 4.0 x 1029 2 days @ 50% in physics 30 nb-1

Commission squeeze – singlebeam 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 2mcollimation 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



28 days total



Results of the alignment with tracks

muons 250 GeV

Sagitta mean value: 3 µm

Sagitta resolution: 150 µm

Statistical error on alignment: 3µm

Studies done with the H8 Testbeam setup

Use 250 GeV muons

mm



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. 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.

StartUp: 100 pb-1

Threshold Prescale

25 GeV 10k

50 GeV 1k

90 GeV 25

170 GeV 1

300 GeV 1

400 GeV 1

1 x 1031 Prescales

Total rate 22 Hz

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



Distance measurements between grid nodes precise to <1 m

***Barrel FSI



CMS Tracker layout

PDPD

TIBTIB

TOBTOB

TOBTOB

TIDTIDTIBTIB

TECTEC

PixelPixel

220

cm

270 cm

4 layersr~20m,z~230m

6 layers

SiTracker: ~15400 modules

6 layersr~35-50m,z~500m

r~10m,z~20m

Trackermaterial budget



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 π0 in EM calo and check shower shapes Understand the beam-halo events as potential background to

large Missing ET events (event selection)



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

E in GeV

Muons

R in cm R in cm

Hadrons

Rather flat rate

Plots based onLHC Project Note 324 (2003)

LHC optic 6.4* in IP1 0.5 m

Beam current 0.54 A

Note: Results are strongly dependenton machine parameter settings. These

settings are not anymore more fully up-to-date. Improved machine simulations are

in preparation!

NHIT1 [Hz]

CMS tot ~1000

Muon ~ 800

Calo. ~ 800

tracker ~ 200

Substantial Expected Rates for E>100 GeV

However, still significantuncertainties in simulations

but probably good enough for a first impression

Very interesting for several commissioningefforts of the endcap regions



Triggering Beam halo muons in CMS

TrackerR<110cm

Beam Halo Muon traverse Trackervolume R<110cm.

There will be a Halo Muon trigger based on the Muon CSCs but the trigger covers only R>~140cm (Tracker R<110cm)

(lowest chambers are ME3/1 and ME2/1)



+ jets ( absolute scale)

- Tower-to-tower response to isolated W

- W mass fitting in tt…

-MET: - Z+jet

“Tools”:

Absolute calibrations:

increasinglumi…

Next slide

Calibrazione dei jets dai dati



Statistics NOT an issue…Systematics: initial state QCD rad.; jet backg. to photons…

kjet≡pTjet/pT

the observablequantity

usingMC truein jet algo

isolated :ET

isol < 5 GeV

Syst.error

[ Threshold: ET

tower>0.5GeV ]

CMS

Calibrazione dei jets dai dati : +jet



DA AGGIUNGERE

iv workshop atlas-cms

Documents

possibleatlascms workshop

workshop atlascms aspettative

infn roma1atlascms workshop

atlas e cms

months pilot physics

il pilot

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