APRIL : a novel Algorithm for Particle Reconstruction at ILC
B. Li, R. Été, G. Grenier, I. Laktineh
备注：
6 pages, 5 figures, proceeding for third conference on Calorimetry for the High Energy Frontier (CHEF), November 25-29, 2019, Kyushu University, Fukuoka, Japan
The current developments for future electron-positron colliders are driven by the Particle Flow concept. In these developments, high granularity calorimeters play a central role. This presentation will focus on a new Particle Flow Algorithm (PFA) developed for high granularity calorimeters, and especially for the Semi-Digital Hadronic CALorimeter (SDHCAL) option of the International Large Detector (ILD) project. The first PFA for ILD was PandoraPFA. This new PFA (APRIL) is based on the PandoraPFA Software Development Kit, but implements a different clustering inspired from the ARBOR PFA approach. This proceeding will describe briefly the APRIL algorithm and discuss its performance against that of PandoraPFA.
After an overview of the modular analysis and reconstruction framework Marlin an introduction on the functionality of the Marlin-based reconstruction package MarlinReco is given. This package includes a full set of modules for event reconstruction based on the Particle Flow approach. The status of the software is reviewed and recent results using this software package for event reconstruction are presented.
In this talk recent simulation results on the single high energy electron reconstruction with the Beam Calorimeter for the ILD detector are presented. Guinea Pig is used to generate the e+e- pair background and GEANT4 for the simulation of electron showers in the calorimeter. An algorithm was developed for the sHEe reconstruction on top of the large e+e- background. The efficiency of the sHEe reconstruction is estimated for the nominal and SB-2009 ILC beam parameters.
The contribution gives an overview of the LCFIVertex package, providing software tools for high-level event reconstruction at the International Linear Collider using vertex-detector information. The package was validated using a fast Monte Carlo simulation. Performance obtained with a more realistic GEANT4-based detector simulation and realistic tracking code is presented. The influence of hadronic interactions on flavour tagging is discussed.
We have explored the reconstruction of kinks from the decay of metastable staus into a gravitino and a stau lepton in the radial region between the outer layer of the vertex detector and the second central tracking layer. After applying a cut on track multiplicity, we find a high efficiency for such events, with minimal background from Standard Model processes.
The precision measurements envisaged at the International Linear Collider (ILC) depend on excellent instrumentation and reconstruction software. The correct identification of heavy flavour jets, placing unprecedented requirements on the quality of the vertex detector, will be central for the ILC programme. This paper describes the LCFIVertex software, which provides tools for vertex finding and for identification of the flavour and charge of the leading hadron in heavy flavour jets. These tools are essential for the ongoing optimisation of the vertex detector design for linear colliders such a…
To evaluate different technologies for calorimetry at the International Linear Collider, the CALICE collaboration has constructed a highly granular analog hadron calorimeter with small scintillator cells, individually read out by silicon photomultipliers. This device has been extensively tested in particle beams. A digital hadron calorimeter based on RPC readout is currently under construction, with first prototype beam test results already available. The high granularity allows detailed investigations of the substructure of hadronic showers, and can also be exploited for the development of so…
This paper describes a new way to reconstruct and identify muons with high efficiency and high pion rejection. Since muons at the ILC are often produced with or in jets, for many of the physics channels of interest[1], an efficient algorithm to deal with the identification and separation of particles within jets is important. The algorithm at the core of the method accounts for the effects of the magnetic field and for the loss of energy by charged particles due to ionization in the detector. We have chosen to develop the analysis within the setup of one of the Linear Collider Concept Detector…
This note discusses methods of particle reconstruction in the forward region detectors of future e+e- linear colliders such as ILC or CLIC. At the nominal luminosity the innermost electromagnetic calorimeters undergo high particle fluxes from the beam-induced background. In this prospect, different methods of the background simulation and signal electron reconstruction are described.
Three methods for handling beam-beam effects in luminosity measurement at ILC are tested and evaluated in this work. The first method represents an optimization of the LEP-type asymmetric selection cuts that reduce the counting biases. The second method uses the experimentally reconstructed shape of the $\sqrt{s'}$ spectrum to determine the Beamstrahlung component of the bias. The last, recently proposed, collision-frame method relies on the reconstruction of the collision-frame velocity to define the selection function in the collision frame both in experiment and in theory. Thus the luminosi…
At the ILC machine induced backgrounds, mainly electron-positron pairs from beamstrahlung, will be the most important source of unwanted interactions. Methods of generating, simulating and imposing pair-background on physics events are presented and influence of this background on ILD reconstruction is reviewed. Effects of the background on various ILD detectors are shown for nominal beam parameters and for SB09 reduced beam parameter set and an example of a physics analysis performed with overlayed pair background is given.
Event reconstruction in the ILC community has typically relied on algorithms implemented in C++, a fast compiled language. However, the Python package pyLCIO provides a full interface to tracker and calorimeter hits stored in LCIO files, opening up the possibility to implement reconstruction algorithms in a language uniquely well suited to working with large lists of hits built with list comprehensions. Python, an interpreted language which can perform complex tasks with minimal code, also allows seamless integration with powerful machine learning tools developed recently. We discuss pySiDR, a…
Glass RPC detectors are an attractive candidate for the active part of a highly granular digital hadron calorimeter (DHCAL) at the ILC. A numerical study, based on the GEANT3 simulation package, of the performance of such a calorimeter is presented in this work. A simplified model for the RPC response, tuned on real data, is implemented in the simulation. The reliability of the simulation is demonstrated by comparison to existing data collected with a large volume calorimeter prototype exposed to a pion beam in an energy range from 2 GeV to 10 GeV. In view of an optimization of the readout pit…
The physics program of future lepton colliders such as the ILC, will benefit from a jet energy resolution in the range 3-4%. The International Large Detector (ILD) reaches this goal over a large range of jet energies. In this paper, we report on the dependence of the simulated ILD performance on various parameters of its silicon-tungsten ECAL. We investigate the effects of dead areas in the silicon sensors, the thickness of the PCB at the heart of the detector, and the robustness of its performance with respect to dead channels, noise, mis-calibration and cross-talk.
The CALICE collaboration has constructed highly granular electromagnetic and hadronic calorimeter prototypes to evaluate technologies for the use in detector systems at the future International Linear Collider. These calorimeters have been tested extensively in particle beams at CERN and at Fermilab. We present analysis results for hadronic events recorded at CERN with a SiW ECAL, a scintillator tile HCAL and a scintillator strip tail catcher, the latter two with SiPM readout, focusing both on the HCAL alone and on the complete calorimeter setup. Particular emphasis is placed on the study of t…
The muons reconstruction package for the SID/ILC detector has been extended to include the Electro-Magnetic Calorimeter. The procedure previously used to reconstruct the charged tracks, an helical fit approximation, has been replaced by a step by step analytical method accounting for the magnetic field and the energy loss by ionization. The trajectory of the muons and the impact of the method on the muon identification efficiency is analyzed. One compares the behavior of muons of different energies in the (x,y)plane and the (px,py) plane of the sub-detectors.
Silicon pad sensors with novel functions of higher timing resolution (LGAD: Low Gain Avalanche Detector) and higher position resolution (PSD: Position Sensitive Detector) are studied for an application to Silicon-Tungsten electromagnetic calorimeter for a detector of the International Linear Collider (ILC). Prototype sensors are fabricated, equipped with dedicated ASICs (Application-Specific Integrated Circuits) and tested with a positron beam as well as a radioisotope. The first results of the measurements of timing resolution with LGADs and position reconstruction with PSDs are reported.
After the construction and successful operation of the first technological prototype of the Semi-Digital Hadronic CALorimeter (SDHCAL), developed within the CALICE collaboration, new R{\&}D efforts have been initiated to fully validate the SDHCAL option for future experiments proposed for the ILC and CEPC colliders. The SDHCAL is a sampling hadronic calorimeter using large Glass Resistive Plate Chamber (GRPC) as active medium with embedded readout electronics. The GRPC prototype size is 1~m$^2$ while future detectors require GRPC detectors with scalable length up to 3~m long (0.9$\times$3~m$^2…
Kyushu University（九州大学）；The University of Tokyo（东京大学）；Osaka University（大阪大学）；Osaka City University（大阪市立大学）
Deep learning is a rapidly-evolving technology with possibility to significantly improve physics reach of collider experiments. In this study we developed a novel algorithm of vertex finding for future lepton colliders such as the International Linear Collider. We deploy two networks; one is simple fully-connected layers to look for vertex seeds from track pairs, and the other is a customized Recurrent Neural Network with an attention mechanism and an encoder-decoder structure to associate tracks to the vertex seeds. The performance of the vertex finder is compared with the standard ILC recons…
The particle flow approach to calorimetry can provide unprecedented jet energy resolution at a future high energy collider, such as the International Linear Collider (ILC). However, the use of particle flow calorimetry at the proposed multi-TeV Compact Linear Collider (CLIC) poses a number of significant new challenges. At higher jet energies, detector occupancies increase, and it becomes increasingly difficult to resolve energy deposits from individual particles. The experimental conditions at CLIC are also significantly more challenging than those at previous electron-positron colliders, wit…
