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"Optimization of the ILC calorimeter for jet-jet mass resolution"


Exploitation of the full physics potential of the ILC requires the detection and identification of W and Z bosons in their hadronic decay modes. Relatively close proximity of the masses of W and Z bosons makes it very challenging and requires that unprecedented jet energy resolution is attained. Such a level of energy resolution can be, perhaps, achieved with the help of t Particle Flow Algorithm by combining the measuring power of tracking systems, electromagnetic calorimetry and hadron calorimetry. Its application requires a method of separation of energy depositions of neutral hadrons (other than pi-zeros) from those of charged particles and photons. To date, it has not been demonstrated that the jet energy resolution required to unearth the physics from an ILC can be obtained. This R&D proposal aims at understanding of limits of the possible attainable energy resolution and their dependence on the detector design.


We plan to investigate factors related to jet-jet mass resolution and their interplay with the detector design. Besides the jet energy resolution they include jet clustering effects, calibration and linearity of the detector response.

The jet energy resolution is optimized with the help of Particle Flow Algorithm. We plan to investigate various methods of cluster analysis to find the most robust method of separation of energy deposits in the calorimeter related to charged and neutral jet components. In addition to the traditional agglomerative clustering methods we plan to investigate a possible use of divisive clustering algorithms.

We plan systematic studies of the performance of the PFA algorithm as a function of the detector design to identify the trade-offs between the detector granularity, sampling frequency, absorber material and the jet energy resolution.

Optimization and performance of the PFA algorithm depends on the simulation of the hadronic showers. We plan to compare and evaluate the available shower simulation models and establish a level of confidence for the performance of the PFA algorithms achievable with the Monte Carlo tools. We expect to develop a plan for the experimental verification of the performance of the PFA algorithm.


The studies will be carried out in close collaboration with the similar on-going efforts at NIU, Argonne and Iowa State U. We plan to investigate complementary clustering strategies of the divisive, rather than agglomerative type and to extend the studies of the jet energy resolution beyond the PFA algorithm.

Please address the following questions in your statement.

  • What are the goals of this R&D project. How does this R&D project address the needs of one or more of the detector concepts?

  • If there are multiple institutions participating in this project, please describe the distribution of responsibilities.

  • Are there significant recent results?

  • What are the plans for the near future(about 1 year)? What are the plans on a time scale of 2 to 3 years?

  • Are there critical items that must be addressed before significant results can be obtained from this project?

  • Is the support for this project sufficient? Are there significant improvements that could be made with additional support?