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Detector status, Computing, Early Physics. John Huth. New LHC machine schedule. A new LHC schedule and turn-on strategy was presented to the CERN SPC and Council three weeks ago The experiments were informed only shortly before, and allowed to communicate it just after the SPC meeting

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New LHC machine schedule

A new LHC schedule and turn-on strategy was presented to the CERN SPC and Council

three weeks ago

The experiments were informed only shortly before, and allowed to communicate it just after

the SPC meeting

The main features of the new schedule are:

- The beam pipe closure date will be end of August 2007 (instead of end of June 2007)

- After that there will still be a few weeks of controlled access to the cavern

- This is followed by an LHC commissioning run with collisions at the injection energy

(450 + 450 GeV), until the end of 2007

- Then there will be a shut-down (typically 3 months) during which the remaining

machine sectors will be commissioned without beam to full energy (7 TeV)

- After that the LHC will be brought into operation for the first physics run at 14 TeV,

with the aim to integrate substantial luminosity by the end of 2008

The LHC Machine Advisory Committee (MAC) has strongly endorsed this new start-up strategy as

the most efficient way to reach 14 TeV collisions

The SPC stressed that the goal should be several fb-1 integrated luminosity at the end of 2008


(Presented by CERN to SPC and Council)

Milestones for the machine

LHC commissioning

- Sectors 7-8 and 8-1 will be fully commissioned up to 7 TeV in 2006-2007. If we

continue to commission the other sectors up to 7 TeV, we will not get circulating

beam in 2007.

- The other sectors will be commissioned up to the field needed for de-Gaussing.

- Initial operation will be at 900 GeV (CM) with a static machine (no ramp, no

squeeze) to debug machine and detectors.

- Full commissioning up to 7 TeV will be done in the winter 2008 shutdown


W  e

Z  ee

Given this new schedule situation, ATLAS stated that the start-up strategy should be

such that the useful integrated luminosity at 14 TeV at the end of 2008 will be maximized

This points towards preferring a few weeks of stable running conditions at the injection energy

as compared to possibly lengthy attempts to reach the maximum possible beam energy of 1.1 TeV

before the full commissioning of LHC power components in the winter shut-down

Primarily the run in 2007 will be a detector and computing commissioning run, much more than a

physics run

(Data taking efficiency (machine x detector) of 30% included

Efficiency of all analysis cuts included)

s = 900 GeV, L =1029 cm-2 s-1

sm at the lhc what can be done with early data

Extensive test beam characterization of prototypes and final modules. Also used for validation of G4 simulations.

  • ‘In situ’ detector calibration:
  • – Cosmics runs;
  • – Single beam and beam gas runs during LHC commissioning;
  • – pp collisions at √s=900GeV (end 2007);
  • – Calibration with physics processes;
  • – Procedure valid for all sub-detectors, ECAL, HCAL, inner trackers, Muon Chambers
SM at the LHC: what can be done with early data?
  • Goals of SM physics studies with early data:
    • Use W, Z and top to calibrate the detector & triggers.
    • Control W, Z, top and QCD multi-jets to properly estimate the background for physics beyond the SM
    • Improve current SM measurements to provide stringent consistency tests of the underlying theory.

few pb-1

L~1030 to 1031 cm-2 s-1

several fb-1

L~1032 to 1033 cm-2 s-1

(end 2008)

early running pp collisions at s 900gev
Early running: pp collisions at √s=900GeV
  • Minimum bias events:
    • interesting for detector commissioning;
    • opportunity to compare to SppS data (reconstruction of secondaries, trigger efficiencies, etc.)
  • For L = 1029 cm-2s-1
    • σMB~50mb (from UA5 measurements)
    • Minimum bias rate: 5kHz
    • L1 trigger rate: 1 – 2kHz (need to understand S/N and random hits)
    • Assuming 1 day at 30% efficiency
      • ~25M – 50M triggered events!
      • few days of data-taking would provide more than enough data for both minimum-bias (can be done with ~104 events) and the underlying event studies (~106 events)!
    • Simple MBTS study indicates acceptance of ~50% (>2 hits in both sides).
    • pT > 0.3 GeV: 60% of charged particles

Colliding protons at √s=14 TeV: the first 10-100 pb-1

How many events at the beginning ?

Goal is to have several fb-1 integrated luminosity at the end of 2008!

  • Assumed selection efficiency:
  • W l, Z ll : 20%
  • tt  l+X : 1.5% (no b-tag, inside
  • mass bin)
  • lots of minimum-bias and jets (107 events in 2 weeks of data taking if 20% of trigger bandwidth allocated)

similar statistics

to CDF, D0 today

~10 pb-1 1 month at

1030 and < 2 weeks

at 1031,=50%

100 pb-1 few days

at 1032 , =50%

  • LHC is a W,Z factory:
    • small statistical errors in precision measurements;
    • can search for rare processes;
    • large samples for studies of systematic effects.
  • Understand/calibrate detector and trigger in situ using “candles” samples
  • e.g. - Z  ee,  tracker, ECAL, muon chamber calibration and alignment, etc.
  • - tt  bl bjj jet scale from Wjj, b-tag performance, etc.
minimum bias measurements
Minimum bias measurements
  • Experimental definition: depends on the experiment’s trigger!
  • “Minimum bias” is usually associated to non-single-diffractive events (NSD), e.g. ISR, UA5, E735, CDF,…

σtot ~ 102 - 118 mb

σNSD ~ 65 - 73mb





  • Modeling of minimum bias pile-up and underlying
  • event necessary tool for high pT physics!
  • Baseline measurement for heavy-ion studies

(see P. Steinberg’s talk, July 13th).

  • Statistics of low pT jets and minimum bias only limited by allocated trigger bandwidth.
more speculative ideas
More speculative ideas
  • Bose-Einstein correlations
    • Shape of “fireball” creating pions
    • Resolution/acceptance
  • RHIC – like variables
    • Front-to-back jet correlations
    • Proton-proton comparisons in advance of heavy ion running
the underlying event in pp collisions at s 14 tev

Central Region

(min-bias dNchg/dη ~ 7)

dNchg/dη ~ 30

x 3

dNchg/dη ~ 15


The underlying event in pp collisions at √s = 14 TeV

Charged particles:

pt>0.5 GeV and |η|<1

Cone jet finder:

Transverse < Nchg >


UE particles come from region transverse to the leading jet.

Pt (leading jet in GeV)



the crimson grid initiative started in april 2004

The Crimson Grid InitiativeStarted in April 2004

A project to engineer a technology fabric in support of interdisciplinary & collaborative computing

Joy Sircar – Division of Engineering and Applied Science

the campus grid vision grid of grids from local to global
The Campus Grid Vision: Grid of Grids from Local to Global








power of campus grids
Power of Campus Grids

GLOW - ~1000 Procs

CG - ~750 Procs

In just 2 campuses !


initiative in innovative computing

Initiative in Innovative Computing

Alyssa Goodman (Director)

Tim Clark (Executive Director)

filling the gap between science and computer science
Filling the “Gap” between Science and Computer Science

Scientific disciplines

Computer Science departments

Increasingly, core problems in science require computational solution

Typically hire/“home grow” computationalists, but often lack the expertise or funding to go beyond the immediate pressingneed

Focused on finding elegant solutions to basic computer science challenges

Often see specific, “applied” problems as outside their interests

where are the optimal iic problems





What is the right

shape for

that boundary?

Where are the optimal “IIC” problems?


“Never Mind”

Domain Science Payoff

Computer Science Department




Computer Science Payoff

iic research branches and projects draw upon 1
IIC Research Branches( and Projects Draw upon >1 )






Plus…Educational Programs that bring IIC Science to Harvard students, and to the public at large.

data intensive project
Data Intensive Project
  • ATLAS/LHC computing – Tier 2
  • Mileura Wide Field Array (MWA) – microwave examination of ultra-redshifted era – time of recombination.
  • Pan-STARRS – optical telescope (Panoramic Survey Telescope And Rapid Response System)
egg project
EGG Project
  • S. Youssef, J. Huth, D. Parkes, M. Seltzer, J. Shank
  • Extension of PACMAN concept to resource allocation, cache management
the lhc inverse mapping problem
The LHC Inverse Mapping Problem
  • A CPU intensive problem
  • N. Arkani-Hamed, G. Kane