We present an end-to-end reconstruction algorithm to build particle candidates from detector hits in next-generation granular calorimeters similar to that foreseen for the high-luminosity upgrade of ...the CMS detector. The algorithm exploits a distance-weighted graph neural network, trained with object condensation, a graph segmentation technique. Through a single-shot approach, the reconstruction task is paired with energy regression. We describe the reconstruction performance in terms of efficiency as well as in terms of energy resolution. In addition, we show the jet reconstruction performance of our method and discuss its inference computational cost. To our knowledge, this work is the first-ever example of single-shot calorimetric reconstruction of
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Software tools for detector optimization studies for future experiments need to be efficient and reliable. One important ingredient of the detector design optimization concerns the calorimeter ...system. Every change of the calorimeter configuration requires a new set of overall calibration parameters which in turn requires a new calorimeter calibration to be done. An efficient way to perform calorimeter calibration is therefore essential in any detector optimization tool set. In this contribution, we present the implementation of a calibration system in iLCDirac, which is an extension of the DIRAC grid interware. Our approach provides more direct control over the grid resources to reduce overhead of file download and job initialisation, and provides more flexibility during the calibration process. The service controls the whole chain of a calibration procedure, collects results from finished iterations and redistributes new input parameters among worker nodes. A dedicated agent monitors the health of running jobs and resubmits them if needed. Each calibration has an up-to-date backup which can be used for recovery in case of any disruption in the operation of the service. As a use case, we will present a study of optimization of the calorimetry system of the CLD detector concept for FCC-ee, which has been adopted from the CLICdet detector model. The detector has been simulated with the DD4hep package and calorimetry performance has been studied with the particle flow package PandoraPFA.
We present optimisation studies for detectors being designed for future e+e− colliders such as CLIC and FCC-ee, using particle-flow calorimetry. Surrounding a large silicon tracker volume, a very ...fine-grained ECAL is envisaged, with 40 Si-W layers and a lateral segmentation of 5 × 5 mm2. Beyond the ECAL, a steel-scintillator HCAL is placed, with 60 (44) active layers for CLIC (FCC-ee) consisting of 30 × 30 mm2 scintillator tiles coupled to SiPMs. The newly developed software chain based on the DD4Hep detector description toolkit is used for the studies, together with the PANDORA particle flow algorithms. Results obtained for the jet energy resolution as well as particle identification efficiencies for the two detector models designed for CLIC and FCC-ee are presented in this contribution.
During the 2009-2013 data taking period (Run I) LUCID was successfully providing information about the luminosity delivered to ATLAS by the LHC. Starting from 2015 (Run II) the LHC machine is ...expected to provide about twice larger peak instantaneous luminosity and the bunch spacing in the machine is decreased by factor of two (from 50 ns to 25 ns). The original LU-CID design could not cope with the new running conditions, which would lead to saturation of photomultipliers and the luminosity algorithms, as well as problems with the lifetime of the photomultipliers. To address these problems a new LUCID detector was built and the readout electronic was redesigned. This article describes the design, the performance, new calibration system and the first results of 13 TeV proton-proton collisions recorded by the new LUCID detector.
Ultra-peripheral heavy ion collisions provide a unique opportunity to study the parton distributions in the colliding nuclei via the measurement of photo-nuclear jet production. An analysis of jet ...production in ultra-peripheral Pb+Pb collisions at sNN=5.02 TeV performed using data collected with the ATLAS detector in 2015 is described. The data set corresponds to a total Pb+Pb integrated luminosity of 0.38 nb−1. The ultra-peripheral collisions are selected using a combination of forward neutron and rapidity gap requirements. The cross-sections, not unfolded for detector response, are compared to results from Pythia Monte Carlo simulations re-weighted to match a photon spectrum obtained from the STARlight model. Qualitative agreement between data and these simulations is observed over a broad kinematic range suggesting that using these collisions to measure nuclear parton distributions is experimentally realisable.
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