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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,

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Presentation on theme: "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,"— Presentation transcript:

1 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 Padova A.Nisati, INFN Roma1

2 U.Gasparini/A.Nisati Atlas-CMS workshop, Bologna 24/11/06 2 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

3 U.Gasparini/A.Nisati Atlas-CMS workshop, Bologna 24/11/ LHC pilot run “Pilot run” ( GeV ): luminosita’: L= – cm -2 s -1  t~10 6 s  Ldt   10 6 = =100 nb -1 Assunzioni “ragionevoli”…: kbkb i b (10 10 )24410  * (m) 11 intensity per beam beam energy (MJ) Luminosity (cm -2 s -1 ) event rate (kHz) W rate (pe24h) Z rate (per 24h) M.Lamont Sept.’06 (~3 “settimane”, ad una efficienza “globale” del DAQ di ~ 50% )

4 U.Gasparini/A.Nisati Atlas-CMS workshop, Bologna 24/11/06 4 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 Provisional Stage I IIIII No beamBeam Hardware commissioning 7TeV Machine checkout 7TeV Beam commissioning 7TeV 43 bunch operation 75ns ops25ns ops IShutdown 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]

5 U.Gasparini/A.Nisati Atlas-CMS workshop, Bologna 24/11/06 5 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…

6 U.Gasparini/A.Nisati Atlas-CMS workshop, Bologna 24/11/06 6 Accuratezza in posizione, ricostruzione di traccia con allineamento “as installed” n Individual modules located on supports to  m in r-  n Support structures (layers/disks/modules) positioned to  m u Interferometry can monitor SCT deformation induced by environmental condition at 1  m level n Whole ID positioned to within 500(200)  m in X(Y) wrt the solenoid axis u Possible rotation up to 0.1 mrad wrt beamline, about 0.1 mrad to solenoid axis n Start system debug and alignment with cosmics and beam-gas interactions n How well will tracks be found initially ? u Use standard track finding u Misalign all modules (SCT/pixel) by ‘local’ installation precision u Misalign all barrels/disks by RMS 100  m l Reasonable estimate of installed precision l Four examples – different misalignments u Study track finding efficiency wrt perfect align. l 94% efficiency for ‘local’ misalignments l 40-60% efficiency for installed precision u Tracks can still be found (with std cuts) l Should really run with relaxed tolerances u With 500  m RMS, serious degradation l Sometimes very few tracks found l Important to build as precisely as possible

7 U.Gasparini/A.Nisati Atlas-CMS workshop, Bologna 24/11/06 7 Analisi di muoni cosmici: posizionamento dei moduli SCT Individual module position to less than 50  m mm 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

8 U.Gasparini/A.Nisati Atlas-CMS workshop, Bologna 24/11/06 8 Allineamento con i dati dalle collisioni pp : stima delle precisioni ottenibili n Calculate r-  alignment precision from one day of low luminosity running (here L=10 33 cm -2 s -1 was assumed) : u Use all tracks in modules, or only overlaps (few 1%) u Results given for middle pixel barrel, and 2 nd SCT barrel n The same is for L=10 31 cm -2 s -1 in the case of hadrons; scale by 10 for muons n Statistics to align pixels to 1- 2  m and SCT to 2-3  m using 1 day of data taking u Limited by data recording rate rather than luminosity u 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 U.Gasparini/A.Nisati Atlas-CMS workshop, Bologna 24/11/06 9 startup: tracciatori in CMS 468 Camere CSC 250 camere DT 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 backup slide per maggiori dettagli]

10 U.Gasparini/A.Nisati Atlas-CMS workshop, Bologna 24/11/06 10 startup: Tracciatore (I) (II) si punta a ~ 30  m nel 2008; raggiungibile… CMS Tracker: “TIB” layer4

11 U.Gasparini/A.Nisati Atlas-CMS workshop, Bologna 24/11/06 11 tracciamento n ~ 15 tracce/evento nell’ accettanza del Tracciatore, con momento medio di ~ 0.5 GeV. u L’ effetto dello scattering multiplo e’ importante u ~10% delle tracce ha p T >2 ECM=14 TeV u Ipotizzando di avere un trigger MB ~ 10 Hz (~10% della bandwidth totale; potrebbe essere maggiore, data la piccola dimensione degli eventi): l 2 tracks/ sec ~10 5 tracce/giorno CMS Pixel, 720 modules “iterative Hits & Impact parameters method”: Convergenza a  x =  y ~10  m OK

12 U.Gasparini/A.Nisati Atlas-CMS workshop, Bologna 24/11/06 12 medio/lungo termine Recente risultato (CMS Computing&Sw Challenge ’06): Allineamento con le tracce dei TOB rods: CMS Si Tracker, ~15,000 moduli 10 6 Z  (iterative Hits & Impact Parameters method) Misalign.~100  m risultato sometime in 2008?

13 U.Gasparini/A.Nisati Atlas-CMS workshop, Bologna 24/11/06 13 Calibrazione del rivelatore di Muoni: ATLAS MDT calibration : t o + r-t relation ultimate accuracy in t o : 0.4 ns needs ~ 10 4 hits/tube  O (10 9 )  -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 toto ns  (t o ) (ns) n

14 U.Gasparini/A.Nisati Atlas-CMS workshop, Bologna 24/11/06 14 MDT calibration : t o + r-t relation ultimate accuracy in r/t : ~10  m needs ~ 2.5×10 4 good  /chamber  O (10 8 )  -triggers (geometry +  included) + temperature+B-field corrections + a lot of computing. t(ns) r(mm) before pp data : average r-t; accuracy: 100  200  m cosmics in ATLAS (10 5 /day×100days  ok) Calibrazione del rivelatore di Muoni: ATLAS

15 U.Gasparini/A.Nisati Atlas-CMS workshop, Bologna 24/11/06 15 Allineamento del rivelatore di Muoni: CMS Misure dal CMS MagnetTest –Cosmic Challenge “(MTCC”): dal sistema di allineamento dei mu dai muoni cosmici (dati MTCC ) L’ obiettivo di una precisione ~100  m sembra essere raggiungibile… misure del “survey” misure dalle tracce

16 U.Gasparini/A.Nisati Atlas-CMS workshop, Bologna 24/11/06 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) “2 tracks” events 1 track events ~5  10 5 muoni /camera/giorno (soprattutto nei sect.3-5, 9-11) …

17 U.Gasparini/A.Nisati Atlas-CMS workshop, Bologna 24/11/06 17 “Pre-allineamento “ Dati cosmici, nella stessa “ruota” (~poche ore di DAQ in caverna) ~150  m - Controllo delle misure col B=0; - LASER necessario con B acceso….

18 18 Allineamento con le tracce del sistema dei muoni in ATLAS : introduzione Two “alignment modes” were tested in H setup: n Absolute alignment : Reconstruct the chamber positions using only the optical sensor responses, the knowledge of their positions and their calibrations. n 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

19 19 Test allineamenti nel Barile: movimenti controllati delle camere n 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 U.Gasparini/A.Nisati Atlas-CMS workshop, Bologna 24/11/06 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  Estimatore dello spostamento dalla posizione ideale di una singola camera del barile ~20 giorni di presa L=10 33 Rivelatore ideale tutte le camere sono disallineate 2 su 4 camere disallineate in un settore di CMS [N.B: si assume perfetta conoscenza del campo magnetico…]   ~100  m

21 U.Gasparini/A.Nisati Atlas-CMS workshop, Bologna 24/11/06 21 Disallineamnti: impatto sulla fisica Impatto su possibili scoperte ‘iniziali’: Esempio: Z’  2  CMS, L= 100 pb -1 (Z  in SO(10) GUT model) “ideal” “first data” scenario potrebbero mostrarsi presto… + ideal

22 U.Gasparini/A.Nisati Atlas-CMS workshop, Bologna 24/11/06 22 Campo magnetico n Understanding magnetic field is important for mass scale u W mass requires overall field integral to < 0.05% (10 G in the 2T Field), other physics processes 0.1%. Principle of the mapping: n Scanning ID volume with 48 Hall probes mounted on two rotating arms in  in radial position from 11.8 to cm: u Hall probes calibrated to about 1G with NMR readings n Four NMR probes are permanently placed at large radius at z=0; n Mapping campaign from June 29 th to August 7 th u Configuration: Complete barrel, no shielding disk, minivan on side C u measurements: 6 points/dm3; ATLAS Solenoid

23 U.Gasparini/A.Nisati Atlas-CMS workshop, Bologna 24/11/06 23 Campo magnetico: il solenoide di ATLAS Field stability : the NMR shows a stability of about 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· Work in progress for further improvments

24 U.Gasparini/A.Nisati Atlas-CMS workshop, Bologna 24/11/06 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 U.Gasparini/A.Nisati Atlas-CMS workshop, Bologna 24/11/06 25 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(%) B gradient at NMR location is < 0.5 mT/cm Work in progress to correct for the probes position Amp ! (nominal is 20500) Most of the results here from A test

26 U.Gasparini/A.Nisati Atlas-CMS workshop, Bologna 24/11/06 26 Campo magnetico: CMS CMS magnet test: esempio di mappa a 3.8 T (Oct. ‘06) B radial component B r (T) B z, r fissato different r different probes Riproducibilita’ a livello di pochi Gauss; grande quantita’ di dati disponibili (misure ridondanti …); analisi in corso

27 U.Gasparini/A.Nisati Atlas-CMS workshop, Bologna 24/11/06 27 Calibrazione in impulso: Le risonanze determineranno la conoscenza della scala in impulso (  controllo mappa campo magnetico & allineamenti ) CMS: 20 giorni di presa 32 [≡200 pb -1 ] 2  in Barrel (|  |<0.8) 1  in “overlap” (0.8<|  |<1.2) 1  in endcap (|  |>1.2) ~30 MeV stat.error.

28 U.Gasparini/A.Nisati Atlas-CMS workshop, Bologna 24/11/06 28 Calorimetri E.M. Pb-liquid argon sampling calorimeter with 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…

29 U.Gasparini/A.Nisati Atlas-CMS workshop, Bologna 24/11/06 29 n The constant term c=c L  c LR ; u The local constant term, c L : 1. Geometry (residual Accordion modulation) 2. Mechanics (absorber & gap thickness) 3. Calibration (with pulse test: amplitude uniformity, etc …) u The “long-range” constant term c LR (from module-to- module miscalibration); n The absolute energy scale Use test beam measurements, cosmic ray run, pp collisions Calibrazione del Calorimetro

30 U.Gasparini/A.Nisati Atlas-CMS workshop, Bologna 24/11/ 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 ~ 10  m  response uniformity <~ 0.3%; 3.Pulse-Test and Testbeam: calibration accuracy of each module ~ 0.4%; 4.Overall “local” constant term: %. 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 mm 2.Sagging/Pear Shape: ~1-2mm effect vs phi (barrel) = 2.2 mm   9  m Test-beam data Resolution: e GeV energy Uniformity: e GeV energy 0,7-0,9% 0,44% Comb TB 2004: 0.55 % over ~30 cells EM Calorimeter, ATLAS Da dove si parte?

31 U.Gasparini/A.Nisati Atlas-CMS workshop, Bologna 24/11/06 31 n 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  Timing EM Cal., ATLAS

32 U.Gasparini/A.Nisati Atlas-CMS workshop, Bologna 24/11/06 32 Calibrazione con i primi dati n 900 GeV data: u Huge uncertainty on luminosity. But Z,W are excluded as calibration probes. l Min.Bias l Jets l J/psi O(10 3 ) events with Et~5GeV for cm -2 s -1 l Inclusive electrons n 14 TeV data: u 10 pb -1 : (10 5 s at cm -2 s -1 ): Z, 10 5 W events, “inclusive” electrons (also Upsilon) l Overall scale in EM barrel, and EMEC OW. è EMEC IW need e-id without tracker. Probably OK for Z identification. ~250 events Barrel-IW per side l Inter-region calibration with Z ~ 1-1.5% u 100 pb -1 : Z, 10 6 W l Stat. Error on energy scale <0.1% l Inter-region calibration with Z ~0.5% l Non-linearity checks

33 U.Gasparini/A.Nisati Atlas-CMS workshop, Bologna 24/11/06 33 ECAL calib: CMS Cosmic datasimulation Tbeam vs Cosmic data Calib.coeff. Punto di partenza: misure in laboratorio(~4%) + test su fascio (5 SuperModuli) + cosmici… [vedi Zotto, commissioning talk]

34 U.Gasparini/A.Nisati Atlas-CMS workshop, Bologna 24/11/06 34 ECAL : CMS All’ inizio con i dati pp: intercalibrazione basata sulla “  symmetry” ~10 7 L1 jet triggers (10 h data 1KHz L1 rate) Limite sistematico (Tracker material budget…) BarrelEndcap precisione raggiungibile: ~ %

35 U.Gasparini/A.Nisati Atlas-CMS workshop, Bologna 24/11/06 35 calibrazione di ECAL in CMS Successivamente : E/p (da W  e ) Int.luminosity precisione raggiungibile Barrel Endcap, 7 fb -1 Serve il Tracker allineato & ben capito… Confronta con lumi richiesta da H  (giusto in tempo…) NOT for 2008…

36 U.Gasparini/A.Nisati Atlas-CMS workshop, Bologna 24/11/06 36 Calibrazione di ECAL in CMS + calibrazione “in situ” con Z  ee (independente dal Tracker): Precisione dell’ intercalibrazione degli anelli a  constante  370 events/ring : ~ 2fb -1

37 U.Gasparini/A.Nisati Atlas-CMS workshop, Bologna 24/11/06 37 Calorimetri Adronici n Cell calibration: u Reference scale (starting point) for individual cell calibration = EM scale l LAr: testbeam and calibration systems: about 1% accuracy on EM scale l Tilecal: testbeam data, Cs calibration ~ 3 % precision on EM scale n Cosmic muons, beam-halo muons u Useful in many aspects è Largon: finding dead channels, cabling errors… è Compare to muon test beam data è Trigger with Tilecal under study n Beam-gas hadrons u Channel mapping; u Study their properties and how to reject them…

38 U.Gasparini/A.Nisati Atlas-CMS workshop, Bologna 24/11/06 38 Minimum Bias & jet events n Monitoring detector response stability: with ~ 1-8x10 6 triggers to reach 1% stability n Cell-to-cell calibration u Using phi-symmetry of MB triggers, inter-calibrate cells with equal dimensions/positions (2x64 cells) n Jet calibration; based on weights estimated from Monte Carlo studies; ingredients: u Jet fragmentation modelling: electromagnetic jet energy fraction, energy and multiplicity of charged hadrons, etc.. u 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. E/p u 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. l 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

39 U.Gasparini/A.Nisati Atlas-CMS workshop, Bologna 24/11/06 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 p T 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). (pT γ+ pTparton )/2 (GeV) pT balance 5% Parton level Particle level Cone 0.7 Reconstruction level Cone 0.7 p T jet p T gamma UE

40 U.Gasparini/A.Nisati Atlas-CMS workshop, Bologna 24/11/06 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 U.Gasparini/A.Nisati Atlas-CMS workshop, Bologna 24/11/06 41 Calibrazione dei jets dai dati QCD dijets balancing: relative calibration “barrel leading jet”(|  |<1) against ‘probe’ jet (any |  |) p T >120 GeV, prescaled to 2.5 Hz ~1 hour data taking 1 x 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 ThresholdPrescale 25 GeV10k 50 GeV1k 90 GeV GeV1 300 GeV1 400 GeV1 CMS ATLAS

42 U.Gasparini/A.Nisati Atlas-CMS workshop, Bologna 24/11/06 42 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, cracks Etmiss 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  E T =300GeV W+jets: evaluate EtMiss resolution up  E T =1 TeV (L=100 pb -1 )

43 U.Gasparini/A.Nisati Atlas-CMS workshop, Bologna 24/11/06 43 Single Trigger lepton (PT=15 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? <> ~ 90  ~ 16 Signal Z   Inclusive W  e Inclusive W   top Z    lepton-hadron Expect in 100pb 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

44 U.Gasparini/A.Nisati Atlas-CMS workshop, Bologna 24/11/06 44 Triggers n Initial luminosity: about L=10 31 cm -2 s -1 ; n Bunch spacing: 75 ns ; u We know which “25 ns” bunch is filled-in; u Excellent opportunity to relax the timing of the several systems u No real problem to identify the Bunch Crossing n Background in the muon system: is expected to be not a concern even in the more pessimistic scenarios u Trigger: time calibration not critical  relax the pulse width of the trigger detector signals u Low occupancy of the muon chambers n 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 U.Gasparini/A.Nisati Atlas-CMS workshop, Bologna 24/11/06 45 Sync.example: CMS muon DT chambers Scan on internal clock phase in each DT chamber (can be parallelized…) Optimal phase: peak ns 9 ns11 ns… 10 ns Mean time (ns) Syncronizing the muon passage on a chamber with the internal clock of the chamber trigger device: Needs 0(10 5 ) “prompt” muons

46 U.Gasparini/A.Nisati Atlas-CMS workshop, Bologna 24/11/06 46 startup: muoni # ev / 10 nb LHC pilot run  Ldt = 100 nb -1 Sqrt(s)=900 GeV ~ prompt  from b/c, p T >6 GeV |  |<2.4

47 U.Gasparini/A.Nisati Atlas-CMS workshop, Bologna 24/11/06 47 Muoni “Prompt” : 900 GeV vs 14 TeV Pythia 6.2,‘default’ min.bias settings  Ldt ~ 100 nb -1 Sqrt(s)=900 GeV ~ prompt  from b/c, p T >6 GeV W Sqrt(s)= 14 TeV  Ldt ~ 10 nb -1 ~ prompt  from b/c, p T >6 GeV, |  | < 2.4 Normalization to  inel = 50 mb ~ 100 W [ in addition, there will be substantial number of K/  

48 U.Gasparini/A.Nisati Atlas-CMS workshop, Bologna 24/11/06 48 Trigger menu Object (GeV)rate(Hz)prescaling Muon 6(5) 406 Muon Dimuons 2x6 (2x5)31 e/  e/  e/2  /2  2x15  201 Jets: 25,50,90, ,10 3,25,1 Dijets,Trijets,...10? ETMiss 25,10030? Minimum Bias205x10 4 and/or random trigger Monitoring/Diagnostics201 TOTAL RATE ~220 ATLAS example, for L= : CMS, single jets, L= ~8 Hz pre-scaling example: 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

49 U.Gasparini/A.Nisati Atlas-CMS workshop, Bologna 24/11/06 49 Segnali di fisica a “Startup”? Non molto di piu’ che jets da QCD (includendo b-jets…e leptoni ‘prompt’ che li accompagnano…)

50 U.Gasparini/A.Nisati Atlas-CMS workshop, Bologna 24/11/06 50 Misure con gli eventi di Minimum Bias n Acceptance limited in rapidity and pt n Rapidity coverage  Tracking covers |  |<2.5 n p T problem u Need to extrapolate by ~x2  Need to understand low pt charge track reconstruction Triggering  MBTS  Random trigger+track trigger v Soft physics, pile-up at higher luminosities, calibration of experiment

51 U.Gasparini/A.Nisati Atlas-CMS workshop, Bologna 24/11/06 51 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 LHC, particularly for B  J/psiX ) CMS simulation (prelim.), both mu reconstructed

52 U.Gasparini/A.Nisati Atlas-CMS workshop, Bologna 24/11/06 52 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~ × × fb -1 ~ 7~ 201.2× fb -1 ~ 21~ 607×10 -9 SM prediction 3.5x GeV trigger studies critical to commission and optimise the trigger  s  s ~20% with 1.3 fb -1 B s mass HLT Offline reco CMS: B s  J/    ATLAS : sensitivity in discovery channel B 0 s → µ+µ-

53 U.Gasparini/A.Nisati Atlas-CMS workshop, Bologna 24/11/06 53 Prima fisica: W W  e W W  BUT: for such purity, good knowledge of MET in the low energy regime (E T 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?) ]

54 U.Gasparini/A.Nisati Atlas-CMS workshop, Bologna 24/11/06 54 Higgs: non molto nel 2008… Tuttavia, essere pronti in (almeno) alcuni canali: e.g. H  WW 10 fb -1

55 U.Gasparini/A.Nisati Atlas-CMS workshop, Bologna 24/11/06 55 …e naturalmente oltre lo SM Example: heavy long lived stau (LSP in GMSB Susy) in CMS muon DT chambers CMS simulation,1 fb -1 1/  P (GeV/c)

56 U.Gasparini/A.Nisati Atlas-CMS workshop, Bologna 24/11/06 56 Conclusioni I primi dati di collisioni pp permetteranno di realizzare molti importantissimi obiettivi: n Sotto-rivelatori: u Le iniziali calibrazioni/allineamenti permetteranno di realizzare alcuni studi di fisica u Le calibrazioni/allineamenti miglioreranno notevolmente con le analisi dei dati iniziali rispetto alle conoscenze di ‘startup’ (test-beam, cosmici, beam-halo) n Dai sotto-rivelatori a ATLAS/CMS: u Trigger commissioning + determinazione delle efficienze u integrazione ed “event building” u Commissioning del software offline n Dai revalatori ATLAS/CMS ai resultati: u Alcune analisi fisiche preliminari: sezioni d’urto W, Z, (top?), spettro dei muoni, dei jets e possibilmente nuova fisica (Z’, B 0 s → µ + µ -, …)

57 U.Gasparini/A.Nisati Atlas-CMS workshop, Bologna 24/11/06 57 Backup

58 U.Gasparini/A.Nisati Atlas-CMS workshop, Bologna 24/11/ “pilot physics” run Sub-phaseBunchesBun. Int.beta*LuminosityTimeInt lumi First Collisions1 x 14 x m1.6 x hours0.6 nb -1 Repeat ramp - same conditions %1.2 nb -1 Multi-bunch at injection & through ramp - collimation days- Physics12 x 123 x m1.1 x % in physics6 nb -1 Physics43 x 433 x m4.0 x % in physics30 nb -1 Commission squeeze – single beam then two beams, IR1, IR days- Measurements squeezed----1 day- Physics43 x 433 x m7 x days - 6 hr t.a. - 70% eff.75 nb -1 Commission squeeze to 2m collimation etc days- Physics43 x 433 x m3.4 x days - 6 hr t.a. - 70% eff.0.36 pb -1 Commission 156 x day Physics156 x 1562 x m5.5 x days - 6 hr t.a. - 70% eff.0.39 pb -1 Physics156 x 1563 x m1.2 x days - 5 hr t.a. - 70% eff.2.3 pb days total

59 U.Gasparini/A.Nisati Atlas-CMS workshop, Bologna 24/11/06 59 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

60 U.Gasparini/A.Nisati Atlas-CMS workshop, Bologna 24/11/06 60 Validation of EM/Had scale with Jets pTj1 = pTj2. 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. StartUp: 100 pb -1 ThresholdPrescale 25 GeV10k 50 GeV1k 90 GeV GeV1 300 GeV1 400 GeV1 1 x Prescales Total rate 22 Hz Inclusive one jet QCD cross section at low p T is a Benchmark measurement. 1% error on jet scale leads to 5% error on cross section at 300 GeV

61 U.Gasparini/A.Nisati Atlas-CMS workshop, Bologna 24/11/06 61 Distance measurements between grid nodes precise to <1  m ***Barrel FSI

62 U.Gasparini/A.Nisati Atlas-CMS workshop, Bologna 24/11/06 62 CMS Tracker layout PD TIB TOB TOB TID TIB TEC Pixel 220 cm 270 cm 4 layers  r  ~20  m,  z ~230  m 6 layers SiTracker: ~15400 modules 6 layers  r  ~35-50  m,  z ~500  m  r  ~10  m,  z ~20  m Tracker material budget

63 U.Gasparini/A.Nisati Atlas-CMS workshop, Bologna 24/11/06 63 Use of Beam Halo data n Order of less than (or close to) 1 Hz/cm 2 charged particles flux (for bunch currents close to the nominal one) is expected; n Very useful to commission the EndCap muon trigger, in particular the Level-1 n Reconstruct tracks in the forward Muon Spectrometer and check the tracking and trigger chambers alignment n Continue studies of track reconstruction in the forward Inner Detector and system alignment n measure π 0 in EM calo and check shower shapes n Understand the beam-halo events as potential background to large Missing ET events (event selection)

64 U.Gasparini/A.Nisati Atlas-CMS workshop, Bologna 24/11/06 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 E in GeV Muons R in cm Hadrons Rather flat rate Plots based on LHC Project Note 324 (2003) LHC optic 6.4  * in IP1 0.5 m Beam current 0.54 A 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! N HIT  1 [Hz] CMS tot~1000 Muon~ 800 Calo.~ 800 tracker~ 200 Substantial Expected Rates for E  >100 GeV However, still significant uncertainties in simulations but probably good enough for a first impression  Very interesting for several commissioning efforts of the endcap regions

65 U.Gasparini/A.Nisati Atlas-CMS workshop, Bologna 24/11/06 65 Triggering Beam halo muons in CMS Tracker R<110cm Beam Halo Muon traverse Tracker volume 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)

66 U.Gasparini/A.Nisati Atlas-CMS workshop, Bologna 24/11/06 66  + jets (  absolute scale) - Tower-to-tower response to isolated W   - W mass fitting in tt… -MET: - Z+jet “Tools”: Absolute calibrations: increasing lumi… Next slide Calibrazione dei jets dai dati

67 U.Gasparini/A.Nisati Atlas-CMS workshop, Bologna 24/11/06 67 Statistics NOT an issue… Systematics: initial state QCD rad.; jet backg. to photons… k jet ≡p T jet /p T  the observable quantity using MC true in jet algo isolated  : E T isol < 5 GeV Syst. error [ Threshold: E T tower >0.5GeV ] CMS Calibrazione dei jets dai dati :  +jet

68 U.Gasparini/A.Nisati Atlas-CMS workshop, Bologna 24/11/06 68 n DA AGGIUNGERE


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