Focus & Future of Nikhef ATLAS Everybody welcome to La Mainaz Jan 18 – Jan 20 Stan Bentvelsen La Mainaz
2 Workshop Main theme: Focus and Future of NIKHEF-Atlas Questions to ask are: -) What do I want to be doing next year? -) In what area am I expert when the beams start to collide? -) Where do I expect help from my collegues at Nikhef? Stan Bentvelsen La Mainaz
3 Aim of the workshop n A lot of presentations are planned… ¡ The presentations are not only aimed to give an overview of the current situation, but are mainly intended to assess: What are the strong points of the NIKHEF group? What is needed to keep it this way? Do we have enough expertise everywhere? Where do we want more / how to get there? This workshop as guidance to discuss our physics interests; It helps to focus our activities! Stan Bentvelsen La Mainaz
4 Atlas at collision time n NIKHEF is very strong in R&D and production of detector hardware for Atlas ¡ ¡ ¡ n Muon chambers SCT endcap MROD / trigger Again, 2005 is a crucial year! MDT chambers installed SCT endcap to CERN MROD production… These projects take most of the time of most of us – and are the cornerstone of our research In the coming year, expect a transition from hardware to harvest We have to prioritize our physics goals! At the end of the day we are judged by scientific output Physics with ‘a capital P’…. Stan Bentvelsen La Mainaz
5 Muon chambers Mega interesting upcoming year: installing MDT in situ ¡ Recording muons when chambers are installed. Do we want to lead these measurements? n n ¡ ¡ Is Nikhef going to be the master of calibration (t-r, t 0, etc…)? What is position Nikhef wrt alignment? n n ¡ ¡ Cosmic muons interesting from physics point of view? Beam halo muons? Traditional in RASNIK Alignment with tracks? What role we play in pattern recognition? Are we interested in track reconstruction? See our Thursday morning session! How we make sure we will find H with our chambers? Stan Bentvelsen La Mainaz
6 SCT project Finishing the SCT endcap on time is top priority and requires help from everybody in the coming period! ¡ ¡ After the SCT has been shipped to CERN: Can we make use of cosmic muons? Beam halo muons? Do we want to run the SCT DAQ? How we want to be involved in the alignment? n n ¡ What is our role in d. Bases? n n ¡ FSI system Tracks from data E. g. Conditional information Alignment See our Wednesday morning session! Pattern recognition and track reconstruction n How are we sure we find tracks in the SCT? Expertise from ZEUS MVD? Stan Bentvelsen La Mainaz
7 Trigger / data flow n n Production of 600 ROBIN’s for buffering data of whole Atlas Production of the MROD modules Data flow simulations How well do we know the trigger? ¡ n Efficiently use of the GRID ¡ ¡ ¡ n Expertise from D 0 of big help here! How we get all data to our desktop? Expertise in running Monte Carlo simulations? Interaction with the PDP group What is the environment in which we will be doing our physics analysis? Stan Bentvelsen La Mainaz
8 Main physics themes NIKHEF ATLAS main focus for physics are: Top quark physics Standard Model Higgs physics Super-symmetry Exotics e. g. extra dimensions My point of view: All our efforts should be directed toward better understanding / study potential for these topics (or at least have in the back of your mind) Stan Bentvelsen La Mainaz
9 Topic choice n The choice for top physics is natural for NIKHEF: top physics ¡ ¡ LHC is a top factory – cross section is huge. Top quarks used as calibration channel during commissioning phase Intrinsic interest in Mtop and σtop to constrain the SM Top is most important ‘background’ for all other exotic physics ¡ We have lot of expertise on top physics from D 0 We have (single) top-theorists at NIKHEF (Eric Laenen) ¡ Top physics requires rather complete set of analysis tools: ¡ n n n Trigger Lepton reconstruction Jet reconstruction Missing Et B-tagging Top quarks provide ideal starting point when beams start to collide. Its there! Without understanding tops no understanding of more complex signals Don’t do Top physics for the whole LHC lifetime! Move on to e. g. tt. H! Stan Bentvelsen La Mainaz
10 Higgs, supersymmetry and exotics n Of course the NIKHEF group has to find the Standard Model Higgs: we are the experts ¡ n Further initiatives: ¡ ¡ n Higgs in association with top-anti-top quark pair (veni) WW scattering in the absence of a Higgs Supersymmetry ¡ ¡ n Especially when its visible in its decay to muons We can use quite a bit of expertise here We have to have the expertise… External help, e. g. from theory group ‘Synergy’ Exotics ¡ ¡ Extra dimensions (Ph. D + veni) Magnetic monopoles Stan Bentvelsen La Mainaz
11 Take the perpendicular view n We need our in-house expertise on ¡ Basic physics n ¡ Trigger n n ¡ n Muon and combined ID and combined Calorimeter n n ¡ Trigger Menu Efficiencies Track reconstruction + pattern recognition n ¡ Event generators External help from phenomenology Jet definitions and properties Missing ET Computing n GRID We cannot do any physics without calorimeter! We need our local expert on calorimeters Stan Bentvelsen La Mainaz
12 Preparation phase n The Physics Topics are not so far away in future ¡ n Commissioning the detectors is starting basically now ¡ ¡ n After first detectors are installed in the Atlas cavern Discussions on commissioning have started at CERN: get involved! All the straightforward ‘bread and butter’ physics has been done ¡ n Schedule to have beam somewhere in 2007 Written up in Atlas physics TDR We now need to generate clever ideas: how to commission the detector Lets dwell on this a little bit more… Stan Bentvelsen La Mainaz
13 Commissioning phase Proton-proton collisions are extremely complex Detectors like Atlas and CMS are extremely complex Do not thrust too much your event generator Do not thrust too much your detector simulation without explicit and full checks with the ‘data’ itself ‘Data’ can be any of the following and more: ¡ ¡ ¡ Other experiments (Tevatron) Internal (sub-) detector consistency Test-beam Cosmic rays Proton-proton collisions Stan Bentvelsen La Mainaz
14 Remarks For reliable results the game to play is: reduce the dependency on MC as much as possible (best to eliminate any dependence) ‘Shake down’ of detector (simulation) in many ways ¡ ¡ Redundancy between detectors Straight tracks, energy clusters, etc… Use Physics: available ‘candlelight’ signals ¡ ¡ Mass of the J/ψ, W±, Z 0, top-quark Presence of b-jets Use constraints: e. g. energy-momentum ¡ ¡ Difficult in pp collisions: Partonic cm not known Balance in PT Stan Bentvelsen La Mainaz
15 Remarks… This does not mean to sit back and wait for data to come! Make clever use of MC to construct ‘MC correction free’ observables Realistically not always possible – find balance Just warn against using MC and simulation ‘blindly’… Stan Bentvelsen La Mainaz
16 Which physics in first year? Event rates in ATLAS or CMS at L = 1033 cm-2 s-1 Low lumi Process N/year Total collected before start LHC W e 15 108 104 LEP / 107 FNAL Z ee 1. 5 107 LEP tt 1 107 104 Tevatron bb 106 1012 -13 109 Belle/Ba. Bar ? H (130) 0. 02 105 ? Already in first year, large statistics expected from: -- known SM processes understand detector and physics at s = 14 Te. V -- several New Physics scenarios Stan Bentvelsen La Mainaz
17 Example: Energy scale calibration n Make use of physics signals to understand the detector ¡ ¡ ¡ n Z-boson: ¡ ¡ ¡ n Abundance of Z and W particles being produced Top quark Various combinations of these with associated particles Properties extensively determined at LEP Mass and width known up-to approx 2 Me. V Mass and couplings described by Standard Model W-boson: ¡ Current precision on mass approx 42 Me. V n n Ultimate goal at LHC to bring down to ~15 Me. V Top-quark ¡ Current mass at 178± 4 Ge. V n Ultimate goal at LHC aprox 1 Ge. V PDG Mass (Ge. V) Width (Ge. V) Z 91. 1876± 0. 0021 2. 4952± 0. 0023 W 80. 425± 0. 038 2. 124± 0. 041 Top 178± 4 Stan Bentvelsen La Mainaz
18 Z 0 e+e- calibration Use the Z 0 mass to calibrate the EM calorimeter Can we get non-uniformity and absolute energy scale from data? ¡ Divide the calorimeter in regions i ¡ Introduce bias for each region by ¡ The Z 0 invariant mass ¡ n Can be written as: By giving all αi a suitable variance, a likelihood fit can be constructed ¡ ¡ Determine βij with lots of Z 0 Untangle the αi Stan Bentvelsen La Mainaz
19 Z e+e- calibration n Method works well ¡ n From parametrized MC study a good correlation is observed between the fitted and injected values for α Difference αinj and αfit Integrated over regions in φ as function of η Energy-loss due to material Test method on full simulation events ¡ Expect non-uniformity due to material distribution Stan Bentvelsen La Mainaz
20 Jet energy calibration Can we utilize the EM scale to say something about the hadronic scale? n E. g. : Use lepton balancing in PT to calibrate the jet energy ¡ ¡ n Again – use the MC to check if the method works in an unbiased way. But method should be independent of MC as possible Jets energy calibration not straightforward n n Both hadronic and electromagnetic energy content. No unambiguous assignment of energy-flow to a jet. ¡ Which particles belong to the jet and which don’t? Stan Bentvelsen La Mainaz
21 Calibration of b-jets using Z or B-jet response different from light quark jet fragmentation – invisible component … n n Rely on relatively rare process Process : ¡ g + b b + Z 0 b jet + + - n Constraint : p. T(b) p. T(Z 0) n First estimation of calibration constant : = p. T(2 )/ p. T(jet) n M(Z)=91. 2 Ge. V Use precise muon tracking to study the scale of b-jets (b-tagged) Jet MC study: g + q q + Z 0 signal q + q g + Z 0 with g qq background Jet reconstruction with Cone algorithm R = 0. 7 p. Tseed = 5 Ge. V; p. T threshold = 15 Ge. V Stan Bentvelsen La Mainaz
22 W-mass determination Stan Bentvelsen La Mainaz
23 Measurement by comparing MC n Relevant quantities ¡ ¡ ν Hadronic recoil U PT of the muon up n I. e. for correct transverse mass MT the PT of the recoil U is needed n Straightforward MC method: ¡ Construct MC ‘template’ for MT by taking into account: n n ¡ Initial State Radiation Angular distributions Recoil model Detector resolution Fit template to data to extract MW W anti-down Hadronic recoil Not the best method! n Heavily rely on details of event generation, Monte Carlo simulation. n Can one be a bit clever and reduce dependency on MC? Stan Bentvelsen La Mainaz
24 MW by comparison to Z data n Use data from process Z ¡ n Factor 10 lower cross section, but with abundant Z production no problem Z up anti-down Z-decays have almost identical topology Hadronic recoil Calculate MT(Z) from remaining muon and recoil ¡ Use the precise knowledge of MZ n Reduce MC dependency ¡ n Substitute one muon by a neutrino ¡ n Transform MT(Z) distribution to MT(W) distribution and extract MW/MZ. ¡ Take difference of production mechanism into account ¡ MC only needed to predict effect of topology difference (small effect) Determination of a ratio and MZ to determine MW Stan Bentvelsen La Mainaz
25 Analysis strategy n To compare W and Z samples: ¡ ¡ n Now MW can be determined from fit to templates MT(W) ¡ ¡ n Use technique to create MT templates for arbitrary mass and width Compare many MTX templates with the observed, measured MTW distribution, to extract MW as MX. Very small uncertainties With 106 events uncertainty ~10 Me. V (stat) Use MC to assess Final State Radiation effects ¡ ¡ Neutrino does not radiate Muon does radiate Completely different use of the MC! Stan Bentvelsen La Mainaz
26 Physics during commissioning n I think we need to start to focus on the commissioning phase of ATLAS ¡ Culminating in ‘ROME’ workshop in June n I think we are able to generate a lot of these ideas to ‘shake-down’ the detectors n I think good ideas in this area require excellent knowledge of the working of the detectors ¡ ¡ n Hands on the knobs of the SCT and Muon: you are the experts! Prime GRID users and initiators I think NIKHEF represents one of the best groups in ATLAS Stan Bentvelsen La Mainaz
27 Tuesday 18 January 2005 Visit to Cern (10: 00 ->18: 45) 11: 00 Visit building 180 (2 h 00') 13: 00 Lunch 14: 00 Visit the Atlas Cavern (1 h 00') 15: 00 Visit CMS (1 h 30') 16: 30 Arrival at Hotel La Mainaz (1 h 00') 18: 45 Diner Evening session (20: 00 ->22: 00) 20: 00 Introduction (30') Stan 20: 30 Hands on 'physics' (1 h 30') Wouter Wednesday 19 January 2005 07: 00 Breakfast 08: 30 First year at Atlas (40') Paul 09: 10 Commissioning with Top (15') Stan 09: 25 Tops at D 0 (30') Frank F 09: 55 Extra dimensions (15') Ivo 10: 10 Physics (20') Nicolo 10: 30 Coffee 11: 00 SCT schedule (20') Patrick 11: 20 Integrating SCT with TRT and beyond (20') Nigel 11: 40 Alignment of SCT (20') Sandra 12: 00 SCT in 2007: experience from ZEUS (30') Els 12: 30 Lunch Ski de fond (13: 00 ->18: 00) Description: Ski de fond in La Vattay - La Valserine. 18: 45 Diner Evening session (20: 00 ->22: 00) 20: 00 Hands-on 'Roofit' (2 h 00') Wouter Stan Bentvelsen La Mainaz
28 Thursday 20 January 2005 Morning session (09: 00 ->12: 00) 07: 00 Breakfast 08: 30 Cosmic Ray stand (20') Pieter 08: 50 Twin tubes (15') Alex 09: 05 Installation (25') Ger. Jan 09: 30 Cosmics in Atlas (15') Charles 09: 45 Graphics in Atlas (15') Charles 10: 00 Coffee 10: 30 Status of muon calibration (25') Martin MROD status (25’) Adriaan 11: 00 Digitization + calibration (25') Niels 11: 30 Focus of the Atlas muon group (50') Peter K 12: 30 Lunch 13: 30 The tt. H signal and the SCT (15') Auke Pieter 13: 45 Single top (20') Zdenko 14: 05 Trigger (30') Marcello 14: 35 Muon movie script (25') Frank L Atlas organization (15: 00 ->16: 00) 15: 00 Atlas papers (15') Paul 15: 15 Physics focus (20') Nicolo 15: 35 Atlas group organization (25') Stan 16: 45 Departure Stan Bentvelsen La Mainaz
29 Rooms here in La Mainaz Wouter Verkerke Double 4 Ger. Jan Bobbink No room Caroline Magrath Double 5 Adriaan Koning Single 1 Ivo van Vulpen Double 4 Frank Filthaut Double 1 Thijs Cornelissen Single 9 Charles Timmermans Double 1 Niels van Eldik Single 9 Nicolo de Groot Single 2 Auke-Pieter Colijn Double 6 Eric Jansen Double 2 Martin Woudstra Double 6 Gustavo Ordonez Double 2 Marcello Barisonzi Double 7 Stan Bentvelsen Single 3 Sandra Muijs Double 3 Els Koffeman Double 3 Maaike Limper Double 5 Peter Kluit Single 4 Zdenko van Kesteren Double 8 Paul de Jong Single 5 Jochem Snuverink Double 8 Frank Linde Single 6 Sacha Caron Double 9 Marcel Vreeswijk Single 7 Pieter Ennes Double 9 Nigel Hessey Single 8 jeroen blok Double 10 Jos Vermeulen verhinderd martijn gosselink Double 10 Fred Hartjes Double 11 Alex Koutsman Double 7 Patrick Werneke Double 11 Stan Bentvelsen La Mainaz
30 Practicalities n Breakfast: ¡ n 12: 30 – 13: 30 hrs Diner: ¡ n Ski de fond in La Vattay tomorrow after lunch ¡ Lunch: ¡ n 07: 00 – 08: 30 hrs n 18: 30 – 20: 00 hrs ¡ ¡ ¡ Meeting point in cafeteria in La Vattay You get shoes + equipment + ski -pass Easy to learn! Make tours around the cafeteria Drinks: ¡ ¡ ¡ Coffee and tea free Drinks free until 11: 00, but keep it within reason! (own responsibility) After 11: 00 pay for your drink (room number) Stan Bentvelsen La Mainaz
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