1. Focus & Future of Nikhef ATLAS
Everybody welcome to
La Mainaz
Jan 18 – Jan 20

2. Stan Bentvelsen La Mainaz
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. Stan Bentvelsen La Mainaz
Aim of the workshop
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
NIKHEF is very strong in R&D and production of detector hardware for Atlas
Muon chambers
SCT endcap
MROD / trigger
These projects take most of the time of most of us – and are the cornerstone of our research
Again, 2005 is a crucial year!
MDT chambers installed
SCT endcap to CERN
MROD production…
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. See our Thursday morning session!
Muon chambers
Mega interesting upcoming year: installing MDT in situ
Recording muons when chambers are installed. Do we want to lead these measurements?
Cosmic muons interesting from physics point of view?
Beam halo muons?
Is Nikhef going to be the master of calibration (t-r, t0, etc…)?
What is position Nikhef wrt alignment?
Traditional in RASNIK
Alignment with tracks?
What role we play in pattern recognition?
Are we interested in track reconstruction?
How we make sure we will find H with our chambers?
See our Thursday morning session!
Stan Bentvelsen La Mainaz

6. See our Wednesday morning session!
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?
FSI system
Tracks from data
What is our role in dBases?
E.g. Conditional information
Alignment
Pattern recognition and track reconstruction
How are we sure we find tracks in the SCT?
Expertise from ZEUS MVD?
See our Wednesday morning session!
Stan Bentvelsen La Mainaz

7. Stan Bentvelsen La Mainaz
Trigger / data flow
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?
Expertise from D0 of big help here!
Efficiently use of the GRID
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. Stan Bentvelsen La Mainaz
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. Stan Bentvelsen La Mainaz
Topic choice
The choice for top physics is natural for NIKHEF:
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 D0
We have (single) top-theorists at NIKHEF (Eric Laenen)
Top physics requires rather complete set of analysis tools:
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. ttH!
Stan Bentvelsen La Mainaz

10. Higgs, supersymmetry and exotics
Of course the NIKHEF group has to find the Standard Model Higgs: we are the experts
Especially when its visible in its decay to muons
Further initiatives:
Higgs in association with top-anti-top quark pair (veni)
WW scattering in the absence of a Higgs
Supersymmetry
We can use quite a bit of expertise here
We have to have the expertise…
Exotics
Extra dimensions (PhD + veni)
Magnetic monopoles
External help, e.g. from theory group
‘Synergy’
Stan Bentvelsen La Mainaz

11. Take the perpendicular view
We need our in-house expertise on
Basic physics
Event generators
Trigger
Trigger Menu
Efficiencies
Track reconstruction + pattern recognition
Muon and combined
ID and combined
Calorimeter
Jet definitions and properties
Missing ET
Computing
GRID
External help from phenomenology
We cannot do any physics without calorimeter!
We need our local expert on calorimeters
Stan Bentvelsen La Mainaz

12. Stan Bentvelsen La Mainaz
Preparation phase
The Physics Topics are not so far away in future
Schedule to have beam somewhere in 2007
Commissioning the detectors is starting basically now
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
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. Stan Bentvelsen La Mainaz
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. Stan Bentvelsen La Mainaz
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, etc…
Use Physics: available ‘candlelight’ signals
Mass of the J/ψ, W±, Z0, 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. Stan Bentvelsen La Mainaz
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. Stan Bentvelsen La Mainaz
Which physics in first year?
Event rates in ATLAS or CMS at L = cm-2 s-1
Low lumi
Process
N/s
N/year
Total collected before start LHC
W e 15
108
104 LEP / 107 FNAL
Z ee
1.5
107
107 LEP tt 1
104 Tevatron bb
106
109 Belle/BaBar ?
H (130)
0.02
105 ?
Already in first year, large statistics expected from:
-- known SM processes  understand detector and physics at s = 14 TeV
-- several New Physics scenarios
Stan Bentvelsen La Mainaz

17. Example: Energy scale calibration
Make use of physics signals to understand the detector
Abundance of Z and W particles being produced
Top quark
Various combinations of these with associated particles
Z-boson:
Properties extensively determined at LEP
Mass and width known up-to approx 2 MeV
Mass and couplings described by Standard Model
W-boson:
Current precision on mass approx 42 MeV
Ultimate goal at LHC to bring down to ~15 MeV
Top-quark
Current mass at 178±4 GeV
Ultimate goal at LHC aprox 1 GeV
PDG
Mass (GeV)
Width (GeV) Z
±0.0021
2.4952±0.0023 W
80.425±0.038
2.124±0.041
Top
178±4
Stan Bentvelsen La Mainaz

18. Stan Bentvelsen La Mainaz
Z0e+e- calibration
Use the Z0 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 Z0 invariant mass
Can be written as:
By giving all αi a suitable variance, a likelihood fit can be constructed
Determine βij with lots of Z0
Untangle the αi
Stan Bentvelsen La Mainaz

19. Stan Bentvelsen La Mainaz
Ze+e- calibration
Method works well
From parametrized MC study a good correlation is observed between the fitted and injected values for α
Test method on full simulation events
Expect non-uniformity due to material distribution
Difference αinj and αfit
Integrated over regions in φ as function of η
Energy-loss due to material
Stan Bentvelsen La Mainaz

20. Jet energy calibration
Can we utilize the EM scale to say something about the hadronic scale?
E.g.: Use lepton balancing in PT to calibrate the jet energy
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
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. Stan Bentvelsen La Mainaz
Calibration of b-jets using Z or 
M(Z)=91.2 GeV
(b-tagged) Jet
B-jet response different from light quark jet
fragmentation – invisible component …
Rely on relatively rare process
Process :
g + b  b + Z0  b jet + +-
Constraint : pT(b)  pT(Z0)
First estimation of calibration constant :  = pT(2)/ pT(jet)
Use precise muon tracking to study the scale of b-jets
MC study:
g + q  q + Z signal
q + q  g + Z0 with g qq background
Jet reconstruction with Cone algorithm
R = 0.7
pTseed = 5 GeV; pT threshold = 15 GeV
Stan Bentvelsen La Mainaz

22. Stan Bentvelsen La Mainaz
W-mass determination
Stan Bentvelsen La Mainaz

23. Measurement by comparing MC
Relevant quantities
Hadronic recoil U
PT of the muon
I.e. for correct transverse mass MT the PT of the recoil U is needed
Straightforward MC method:
Construct MC ‘template’ for MT by taking into account:
Initial State Radiation
Angular distributions
Recoil model
Detector resolution
Fit template to data to extract MW ν  W up
anti-down
Hadronic recoil
Not the best method!
Heavily rely on details of event generation, Monte Carlo simulation.
Can one be a bit clever and reduce dependency on MC?
Stan Bentvelsen La Mainaz

24. MW by comparison to Z data
Use data from process Z
Factor 10 lower cross section, but with abundant Z production no problem
Substitute one muon by a neutrino
Z-decays have almost identical topology
Calculate MT(Z) from remaining muon and recoil
Use the precise knowledge of MZ
Transform MT(Z) distribution to MT(W) distribution and extract MW/MZ.
Take difference of production mechanism into account   Z up
anti-down
Hadronic recoil
Reduce MC dependency
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. Completely different use of the MC!
Analysis strategy
To compare W and Z samples:
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.
Now MW can be determined from fit to templates MT(W)
Very small uncertainties
With 106 events uncertainty ~10 MeV (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
I think we need to start to focus on the commissioning phase of ATLAS
Culminating in ‘ROME’ workshop in June
I think we are able to generate a lot of these ideas to ‘shake-down’ the detectors
I think good ideas in this area require excellent knowledge of the working of the detectors
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. Stan Bentvelsen La Mainaz
Tuesday 18 January 2005
Visit to Cern (10:00->18:45)
11:00
Visit building 180 (2h00')
13:00
Lunch
14:00
Visit the Atlas Cavern (1h00')
15:00
Visit CMS (1h30')
16:30
Arrival at Hotel La Mainaz (1h00')
18:45
Diner
Evening session (20:00->22:00)
20:00
Introduction (30')
Stan
20:30
Hands on 'physics' (1h30')
Wouter
Wednesday 19 January 2005
07:00
Breakfast
08:30
First year at Atlas (40')
Paul
09:10
Commissioning with Top (15')
09:25
Tops at D0 (30')
Frank F
09:55
Extra dimensions (15')
Ivo
10:10
Physics (20')
Nicolo
10:30
Coffee
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
Ski de fond (13:00->18:00)
Description:
Ski de fond in La Vattay - La Valserine.
Hands-on 'Roofit' (2h00')
Stan Bentvelsen La Mainaz

28. Stan Bentvelsen La Mainaz
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')
GerJan
09:30
Cosmics in Atlas (15')
Charles
09:45
Graphics in Atlas (15')
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 ttH 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. Stan Bentvelsen La Mainaz
Rooms here in La Mainaz
Wouter Verkerke
Double 4
GerJan Bobbink
No room
Caroline Magrath
Double 5
Ivo van Vulpen
Thijs Cornelissen
Single 9
Niels van Eldik
Auke-Pieter Colijn
Double 6
Martin Woudstra
Marcello Barisonzi
Double 7
Sandra Muijs
Double 3
Maaike Limper
Zdenko van Kesteren
Double 8
Jochem Snuverink
Sacha Caron
Double 9
Pieter Ennes
jeroen blok
Double 10
martijn gosselink
Alex Koutsman
Patrick Werneke
Double 11
Adriaan Koning
Single 1
Frank Filthaut
Double 1
Charles Timmermans
Nicolo de Groot
Single 2
Eric Jansen
Double 2
Gustavo Ordonez
Stan Bentvelsen
Single 3
Els Koffeman
Double 3
Peter Kluit
Single 4
Paul de Jong
Single 5
Frank Linde
Single 6
Marcel Vreeswijk
Single 7
Nigel Hessey
Single 8
Jos Vermeulen
verhinderd
Fred Hartjes
Double 11
Stan Bentvelsen La Mainaz

30. Stan Bentvelsen La Mainaz
Practicalities
Breakfast:
07:00 – 08:30 hrs
Lunch:
12:30 – 13:30 hrs
Diner:
18:30 – 20:00 hrs
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)
Ski de fond in La Vattay tomorrow after lunch
Meeting point in cafeteria in La Vattay
You get shoes + equipment + ski-pass
Easy to learn!
Make tours around the cafeteria
Stan Bentvelsen La Mainaz