Initial physics and plans for cms
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Matthew Jones (associate professor) David Silvers (graduate student – supported by NSF CAREER award). Early physics results ϒ production properties overlaps with CDF physics program Detector characterization using available data Absolute track reconstruction efficiency

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Initial physics and plans for cms

Matthew Jones (associate professor)

David Silvers (graduate student – supported by NSF CAREER award)

Early physics results

ϒ production properties overlaps with CDF physics program

Detector characterization using available data

Absolute track reconstruction efficiency

Longer term interests

Trigger hardware upgrade

Initial Physics and Plans for CMS

http://www.physics.purdue.edu/~mjones/talks/mjones_cms_Aug_2010.ppt

2010 DOE virtual site visit


Physics context
Physics Context

  • Involvement in CMS physics program is a natural extension of CDF interests:

    • Small data samples, but large cross sections.

    • Interesting physics questions that merit further investigation.

      • Extended rapidity coverage alone is very useful.

    • Analysis of muonic final states form a coherent effort at Purdue.

    • Purdue involvement has already influenced the structure of CMS analyses: strong emphasis on proven experimental techniques developed at CDF.

2010 DOE virtual site visit


Track reconstruction efficiency
Track Reconstruction Efficiency

  • Motivated by analysis which was patterned after the CDF J/ψ cross section measurement.

    • Allows muon/selection efficiencies to be determined using data rather than based entirely on Monte Carlo

    • Define muon selection/reconstruction efficiencies relative to tracking efficiency

    • Measure track reconstruction efficiency by embedding simulated hits in data events

      • Precision not limited by available statistics

      • Non-trivial interface with event data model

      • General interest in CMS, but in particular from the heavy ion group: very difficult to measure in any other way.

2010 DOE virtual site visit


Example from track embedding analysis
Example from Track Embedding Analysis

  • Results from CMS AN-2010/209 and public TRK-10-002:

  • Tracking acceptance is well modeled by detector simulation.

  • Efficiency is high, but not accurately described by the simulation.

    • Differences may become increasingly important at high luminosity

    • Suggest sensitivity to local activity, ie. proximity to jets

  • This powerful framework allows detailed studies of these effects.

  • Complementary to other estimates of tracking efficiency which average over wide ranges of kinematic variables.

  • These results used to support a variety of analyses presented at ICHEP, but in particular were used directly in ϒ cross section measurement.

Monte Carlo

Data

2010 DOE virtual site visit


Longer term interests
Longer Term Interests

  • Prior experience operating CDF at high instantaneous luminosity, L1/L2 hardware upgrades.

  • Infrastructure in place at Purdue for design and production of contemporary electronics systems.

    • Currently capitalizing on availability of good students from department of Electrical and Computer Engineering.

  • Interested in hardware development for extending L1 trigger capability at CMS.

  • Currently supported by NSF award, but overlaps with commitments to DOE.

2010 DOE virtual site visit


Example from pixel jet trigger studies
Example from Pixel Jet Trigger Studies

  • Construct Level-1 trigger primitives from sensors in barrel pixel detector:

    • Identify jets, measure η, φ and z-vertex position: achievable resolutions well matched to calorimeter segmentation.

    • Provide z-vertex position information to L1 calorimeter trigger

    • Controls rate of multi-jet triggers when multiple interactions per bunch crossing.

  • Studies performed using emulation of “implementable” hardware:

    • Fast pattern recognition in FPGA’s

    • Bandwidth constraints on existing fibers

  • Results presented at CMS upgrade workshop, October 2009.

  • However:

    • Currently unclear how this would fit in with upgrade efforts.

    • Strong support from Wisconsin, Fermilab: provides a way to learn about advanced trigger hardware before it becomes essential for CMS operations.

    • Less strong support from PSI: Why can’t we just increase jet trigger thresholds to control rates?

    • Long term plan must evolve with the evolving constraints on CMS upgrade efforts.

2010 DOE virtual site visit