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CMS Programme

India  CERN  LHC  CMS  India-CMS

Kajari Mazumdar (on behalf of India-CMS collaboration) Tata Institute of Fundamental Research Mumbai

Plan is to cover briefly relevant hardware, software and physics topics. Additional material in talks by Pant, Shukla, Shivpuri . India-CERN meeting, BARC Feb. 28, 2011

• Long association with CERN: Emulsion, Bubble chamber, LEP

good name and also rapport of Indian scientists

• LHC enthusiasts’ (Rubbia, Hoogland, ..) visits India from early 90’s.
• Groundwork done by Profs. Malhotra, Ganguly and others.
• Indian scientists in LHC experiments from nascent, R&D stage.
• First Indian group formally in CMS experiment in1994.

LHC programme: more multi-dimensional with participation in accelerator, experiment and grid computing. Under India-CERN umbrella each community functions independently. Projects funded by govt. agencies: Dept. of Atomic Energy (DAE) and

• Dept. of Science & Tech. (DST).

Prologue

Today, 6-7 Indian groups in CMS, thriving well.

• TIFR, BARC, Delhi U., Panjab U., Visva-Bharati U, NISER, SINP

About 40-50 physicists, engineers (+ techinical staff ) More teams expected in future

• TIFR is the host institute for India-CMS collaboration.
• Significant contributions in various fronts, though limited by

‘distance’ and ‘time-zone’ factors.

• Hoping for better visibility and support in CMS collaboration in

future!

India-CMS collaboration

• 40 students till now, about 10 finished Ph.D. during last 7-8 years.
• More influx of teams, students expected in coming years.

Please help us in more faculty recruitment!

• Hardware (both in R&D and fabrication in current phase)
• Preparatory studies with physics simulation, contributions in

LHCC and other milestone documents. Enthusiasm and moral support of Denegri acknowledged.

• Software: detector simulation, GEANT specific developments
• Test Beam activities for HCAL
• Grid computing (Tier2 centre)
• Analysis of real data => contribution in publications
• -- Cosmic muons recorded in CMS
• -- Collision data (both p-p and Pb-Pb)
• Representing CMS collaboration in international fora.

Participation of India in CMS experiment till now

• Detector upgrades, related simulations
• Sub-detector related R&D, participation in test-beam activities.
• Studies for physics potential for brighter scenarios of LHC
• More involvement in remote simulation and analysis
• Participation in various responsibilities of CMS (to be enhanced)
• Remote Operations Centre for the Asian zone requested
• Partial support for students for longer stay at CERN requested

Open to ideas for other possibilities as well.

Participation in CMS in future

Present hardware participation in CMS

• 1. Outer Hadron Calorimeter (HO) :

TIFR+ Panjab University reduce energy leakage from HCAL: additional depth -->hermetic detector improves resolution for measurement of missing transverse energy, key observable to discoveries Scintillator with HPD/SiPM as light readout 432 Plastic scintillator trays (4-6 units) covering ~ 400 sq. m – 2160 readout channels – 72 honeycomb panel housings (size 2.5 m X 2.0 m)

• 2. Si Pre-Shower Detector (PSD) in EM CAL endcap ( talk by R.K.Shivpuri)

BARC (+ BEL) + Delhi Univ.

• 3. Resistive Plate Chamber (RPC) (talk by L.M.Pant)

BARC + Panjab Univ.

Tile with 4-s groove 5 to 6 tiles in

• tray. Fibres ganged together to

form pigtail, to be connected via clear fibres to photo detector Pigtail with connector

• 6 trays assembled

side by side in a HO housing

• various Quality

Controls at each step. eg, MIP signal using cosmic muons.

• One HO module being installed on a muon ring on

surface (2006)  non-trivial coordination with others.

• 3-4 personnel from India at CERN at a given time  for

Installation, monitoring detector health at every stage.

HO detector Responsibility: fabrication of scintillator detectors and quality controls.

HO detectors, alongwith muon stations,being lowered down the shaft to underground area

In the underground pit

• Efficiency of HO detectors during

2010 data taking : about 97%

• Calibration of HO using cosmic

muons.

• Shift duties by Indians
• Participation in HO readout upgrade

Issues:

• HO elements do not have adequate signal to background ratio for MIPs
• HPDs in non-central position have discharging tendency

Solution: – Replace HPDs with state of-the-art device SiPM – Provides excellent S/B ratio for muons – Insensitive to ambient magnetic field

SiPM characterization facility

– Setup for V-I characteristic, single pixel calibration, linearity, MIP studies at Ooty lab. (near Bangalore)

Packaging and assembly of bare SiPMs demonstrated at Bharat

Electronics Limited (Bangalore)

CMS-HO Calorimeter: present status & near-future activity

Validation of SiPM for CMS environment – Testbeam studies, stability, radiation hardness, magnetic field immunity, saturation effect SiPM Control Boards fabrication

• Prototype fabrication carried out in India
• Production and quality control of 150 boards in India expected

Participation in Installation – Assembly of R/O box, QC and burn-in test at CERN

CMS-HO Upgrade plan: TIFR responsibility

Possibility for fabrication of SiPM at India being probed.

LHC Grid Computing & CMS-T2 centre

• One of the 5 CMS Tier2 (T2-IN-TIFR ) sites in Asia Pacific region
• perating since last 3 years. Logical parent T1: ASGC, Taiwan
• Serving about 60 users from 6 institutes/universities in India
• CMS collaboration (>3000 people) uses the facility for

coordinated central Monte Carlo event production  planned data storage (both collision and simulation)  remote analysis of physics data with latest CMS software by any member of CMS collaboration

CMS recognizes the performance  credit points exchanged against mandatory jobs by collaborators.

• Resources acc. to pledge: > 500 CPU cores, 600 TB storage

 can host lots of data to the advantage of whole collaboration, Indian physicists and particularly students.

• Availability and reliability of site almost 100% in recent months.

(occasional short periods of bad network situation)

• Latest versions of software and middleware, regular updates.
• Trouble shooting operations taken up fast by support staff.
• Data transfers at good rates (typical latency: 10 to 30 min.s).
• Good success rate of jobs during last 6 months.

With more intense LHC machine performance in coming years expects to serve the community well.

Site performance

Key to grid computing: network bandwidth

• Dedicated P2P link between CERN and India since several years.

 presently 1Gbps, likely to be upgraded

• With requirements of CMS computing (different from ALICE), connection

to other T1s achieved (8 more) via peering at CERN end.

• Other internet facilities are improving continuously in recent times

Significant for site performance, connected to other T2s.

• Site taken up for hosting important data streams.
• Hubs hosted at TIFR, maintained jointly by CDAC + TIFR.

Presently other centres / institutes connected to outside world via TIFR

• With NKN connections fully operational in the country in near future,

site expected to play bigger role for LHC data analysis by collaborating

• institutes. (talk on Grid by Apte)

Future possibility to use for other purposes (medical, weather, outreach,.)

Some numbers for the period of Jan. to Dec. 2010

• Total amount of data transfers: 350 TB upload, 313 TB download

Much more traffic expected from this years onwards

• Total number of jobs at site: 674971 (tests + simulation + analysis)
• Successful simulation event production jobs : 46510

Average cpu time for 1 p-p collision event simulation ~2.5 s

• Successful event analysis jobs: 76701

Processed events, cumulative, in 2010 1.7e9 Submitted jobs rate in 2010 12K

Physics effort from at India

• simulation studies, analysis done mostly from India (+short stays @CERN).
• during last several years using grid.
• regular presentations of updates remotely over the network.
• active discussions among CMS physicists, theorists.

Participation in pre-collision era:

• 1. Physics simulation studies to estimate CMS potential

 SUSY in trilepton mode  invisible Higgs in vector boson fusion process,  Z   e, as benchmark for   e ,  Zbb process Search for charged higgs  several topics with heavy quarks, etc.

• 2. Test beam: study of detector response, validation of GEANT4

physics of hadronic interactions.

• 4. calibration of HO subdetector modules
• 5. Trigger studies

• about 1 billion events collected in CMS detector during 2008.
• efficiently used for commissioning of CMS experiment in multiple ways.

 angular dependence of muons  data-driven method for L1 muon trigger efficiency in different regions (S.Bansal, published in JINST)

Analysis of Cosmic ray events (while waiting for collision )

Z × Φ map for RPC efficiency using Tag&Probe method

Physics with collision data

Physicists involved heavily in several analyses

 topic choice based on personal taste, applicable wisdom Notably, direct contributions in ~10 physics publications based on p-p collision data of 2009, 2010.  significant contribution in analysis of heavy ion data as well. (talk by Shukla) Participation in analysis reviews. Presentations of CMS physics results on behalf of whole collaboration by Indians (physicists and students) at international conferences. First Ph.D. thesis (S.P.Singh) using collision data, in Aug.,2010.

Responsibilities for trigger measurement, data quality monitor, etc.

• Hadronic event shapes
• Underlying event analysis using jets reconstructed from tracks only
• UE analysis using Drell-Yan events
• QCD properties in hard jet events
• Jet production in association with W, Z bosons
• Prompt photon production
• W charge asymmetry in production using muon channel
• Diboson event properties: Win muon final state
• Drell-Yan events (muon)
• Z   eX
• Z’    hadronic final states
• exotica in electron, photon final states (e*e  e+e- ,GMSB
• Search for Higgs in WW 2l 
• Search for Higgs in ZZ 2l

Physics Menu chosen at present

There is lot of interesting physics in every collision

• Detailed understanding of softer processes  Discovery in hard, rare processes
• CMS measures (almost) everything beautifully  excellent physics output!

Hadronic event shape variables

Agree with Pythia6, Pythia8 and Herwig++ , Disagree with Madgraph and Alpgen Central thrust Thrust minor

Event Shape variables can distinguish different models of QCD multijet production Possibility with large statistics: measurement

• f αs

Pythia6

Pythia8 Herwig Madgraph Alpgen

Pythia6 Pythia8 Herwig Madgraph Alpgen

3.2pb−1 CERN-PH-EP-2010-072 To be publishd in PLB

UE measurement using Track-based Jets

• 7 TeV and 900 GeV results including tunes for soft QCD: D6T and DW predictions
• Charged multiplicity density and pT density profiles.
• Fast rise for pT< 8 GeV/c (4 GeV/c)  increase of MPI activity
• Plateau-like region (≈ constant average number of particles + slow increase of pT)

 saturation regime

• MPIIncrease of the UE activity with energy
• Stat. dominating

at high pT Headed for publication in JHEP

UE measurement using Drell-Yan events @ 7 TeV

• Cleanest process to measure UE!

Everything excluding two leptons is UE.

• Unlike leading jet case, there is no colored FSR.
• Scale is set by Z pT and lowest scale is set by Z mass.
• For discovery, UE need to be measured for reasonably hard events, not possible,

using hadronic final states.

• Away region is affected by away jet, which balances Z pT.
• Transverse and toward regions are most sensitive for UE studies

Work in progress

W→μν asymmetry and parton distribution function

Charge asymmetry to constraint parton distribution functions of proton  sea quark content wrt valence quarks  W+ is produced more preferenatially compared to W- at LHC

μ+ μ−

CERN-PH-EP-2011-024  PLB Ph.D thesis of A. Saha

Study of W events in muon channel

Diboson productions : Standard Model gauge structure  self-interactions among gauge bosons: W, WW, Z(no ZZ,vertices), WZ, ZZ

• -> important backgrounds for Higgs searches



W largest cross section W cross section measurement – step towards measuring WW coupling.

Born level diagrams Higher order diagrams WW coupling ( pp WX + X, theory, NLO) pb = 49.44 ± 3.8 (exp) pb = 55.4 ± 6.93 (stat.) ± 4.86 (syst.) ± 6.09 (lumi.) To be published in JHEP, + presentation in students' session at Moriond conf. by D.Majumder Ph.D thesis of D. Majumder

Drell-Yan process: differential cross-section

• Standard Model electroweak benchmark, not spoilt by QCD!
• Handle on PDF through normalized measurement of dσ/dM
• Background for New Physics searches (extra heavy gauge

boson Z’ decaying to lepton pairs)

dσ/dM

σ 60<Mμμ 120GeV = 932 ± 9 stat ± 25 syst ± 11%,lumi pb

This measurement, with 36 pb-1 CMS in JHEP with 3 pb-1 924 ± 31 ± 22 ± 102 pb

Theoretical expectation: 970 ± 40 pb

Not final as yet, to be presented in Moriond Major discoveries of last century with CMS

First beam at LHC: Sep. 2008, first collision at 7 TeV on March 30, 2010  Public outreach at TIFR, Mumbai, by live display of activities at CERN

Some steps being taken, though not sufficient:

• Regular scientific seminars on important results from LHC
• Dissemination of LHC highlights among non-HEP colleagues

24X7 display of status of LHC accelerator, CMS experiment, and live events. Tier2 status

LHC related popular talks at schools, public places

• LHC related colloquium at various institutes/universities
• Participation in TIFR Open Day programme every year

Introductory talks on LHC for graduate students, summer students

• Occasional reports in media

Public lectures at TIFR (by Heur, ..)

Will be keen to join LHC@home scheme!

Outreach, Education

A Personal Conclusion

• Proud to be Indian AND in CMS experiment!
• CMS experiment is doing very well and the harvest is very
• encouraging. We have a very exciting time ahead.
• LHC is at the dawn of a new era in high energy physics.
• LHC has already changed our lifestyle!
• LHC will change the way mankind thinks of the universe.
• Due to timely initiatives of previous generation of scientists at

both ends today we participate in the world-wide front ranking efforts.

• The potential of Indian contribution in CMS is huge and

recognized already, but more needs to be done in to harness it completely. I will do my best in this regard.

THAN ANK YOU !

BACKUP

Behind the Tracker and in front of EE 2 Pre-shower Endcaps (SE) Coverage: 1.653<||< 2.6 1000 detectors

Silicon Preshower

• Responsibility of BARC, Delhi University
• fabrication at Bangalore with close

supervision from BARC

• Quality of detectors comparable to that of

Hamamatsu  CMS requested for more production.

Physics motivation: accurate measurement of Higgs   decay

Hybrid with front end Electronics-PACE chip

Silicon detector made in BEL, Bangalore, on micro- module made at CERN

Detector mounted on ceramic & Al tile

The two separate ES Dees

Assembly/mounting at CERN

1 Gbps to CERN peered to GEANT

2.5 Gbps TEIN3 via NKN (both to East and West)

1 Gbps GLORIAD to Chicago, US

TIFR-INDIACMS T2

250 Mbps to other VECC RRCAT, IPR

VECC/SINP-INDIAALICE

Key to grid computing: network connections

CMS detector ¼ Longitudinal View

HB HE HF HO

HO: Physically attached with CMS barrel muon stations, subdivided into 5 annular rings, covering the barrel region of || <1.6, positioned behind magnet iron, 2 layers for || < 0.36

Quality control tests at India

Low-noise SiPM and its characteristics

LED calibration pulse in SiPM

HPD discharge noise in magnetic field