European Organization for Nuclear ResearchOrganisation Européenne pour la Recherche Nucléaire

High-Energy Physics Data

Delivering Data in ScienceICSTI Winter Workshop

Tim Smith – CERN/IT Department

Tim Smith @ ICSTI Workshop, Mar 2012 <2>

Delivering Data in HEP

• Data Storage and Stewardship

• Distribution and Access

• Interpretability, Reusability and Citability

Tim Smith @ ICSTI Workshop, Mar 2012 <3>

LHC and the Data Deluge

150 million sensors

40 million times /sec

22 PB in 2012

Tim Smith @ ICSTI Workshop, Mar 2012 <4> 4

Just a Drop in the Ocean! …Selection

Particle

Protons/bunch 1011

Crossing rate 40 Million /sec

Collision rate 1 Billion /sec

Parton(quark, gluon)

Proton

Bunch

SUSY.....

HiggsZo

Zoe+

e+

e-

e-

Filter to200 /sec

Tim Smith @ ICSTI Workshop, Mar 2012 <5>

Data Storage

6 GB/s

Tim Smith @ ICSTI Workshop, Mar 2012 <6>

Data Stewardship: Migration

LHC era 60 PB

LEP era 100 TB

Tim Smith @ ICSTI Workshop, Mar 2012 <7>

Data Distribution & Access

11 T1140 T2

T3s

Worldwide LHC Computing Grid

Tim Smith @ ICSTI Workshop, Mar 2012 <8>

Data Access

Publication data

Derived physics data

Analysis Object Data

Reconstructed Data

Raw Data / Simulated Data

70 PB Worldwide

x N

x tens

x few

22 PBT0

T1

T2

T3

Tim Smith @ ICSTI Workshop, Mar 2012 <9>

Data Access ≠ Data UsabilityData Access ≠ Data Usability

Tim Smith @ ICSTI Workshop, Mar 2012 <10>

Data Reuse: Raw/Processed Data

• Reuse of the Reconstructed & Analysis Object Data– Calibrations, Configurations– Conditions DBs: tens of TBs

– Reconstruction and identification algorithms– Detector response parameterizations– Software: millions of lines-of-code

Tim Smith @ ICSTI Workshop, Mar 2012 <11>

Data Reuse: Publication Data

• Published observables– Model-independent measurements– Distributions and cross-sections– HEPData: tabular– DOIs

• Rivet routines– Parameterize analysis acceptance– Compare simulated & measured data– http://rivet.hepforge.org/

Tim Smith @ ICSTI Workshop, Mar 2012 <12>

Data Reuse: Derived Physics Data

• Access, ability to reinterpret– Reanalysis with new QCD calculations– Combination with data from future colliders– …serendipitous discovery

• Pitfalls: Large investment of effort required– Correlations, efficiencies, systematic uncertainties– Backgrounds estimated from data driven techniques

• Intertwined with event selection criteria

• Searches…

Tim Smith @ ICSTI Workshop, Mar 2012 <13>

Data Reuse: Derived Physics Data

• RECAST– Limits of an existing search

for an alternative hypothesis– Brokering service– Collaboration

• Archives the analysis code• Provides authority

• Digital Preservation in HEP– http://www.dphep.org/

Tim Smith @ ICSTI Workshop, Mar 2012 <14>

WLCG

Delivering HEP data to

scientists around the

world

Tim Smith @ ICSTI Workshop, Mar 2012 <15>

Questions ?