Simulation Study of Energy Resolution of the Electromagnetic Shashlyk Calorimeter for Different of Layers and Absorber Combinations

The response simulation of an ideal KOPIO-type electromagnetic sampling calorimeter was carried out in the energy range of 50 MeV – 16 GeV using Geant4-10.6.0 toolkit. In this work, we obtained energy resolution parameters for prototypes of Shashlyk calorimeter modules (ECAL SPD) of the NICA collider SPD setup for different thicknesses of a lead absorber with different numbers of layers. The NICA scientific experiment provides a unique opportunity to study parton distributions and correlations in hadron structure when working with high-intensity polarized relativistic ion beams. The ECAL electromagnetic calorimeter is one of the key detectors of the SPD device. There are some preliminary requirements for an electromagnetic calorimeter, in particular, for energy resolution in the energy range from 50 MeV to 16 GeV. It has been shown in detail that a more accurate obtaining of stochastic as well as permanent coefficients acting as parameters of the energy resolution parameterization formula is possible when longitudinal energy leakages from the calorimeter tower are taken into account. Such leakages are always present even in small amounts. Thus, the energy resolution parameterization of an ideal sampling calorimeter with a good χ 2/ndf value is fitted with function of the type: σE/E=(a/√E) (+)b(+)(p1ln1E+ p2ln2E + p3ln3E ) , where the logarithm lnE means ln(E/Ec), where Ec is the effective critical energy. Based on the results of detailed modeling, the dependence of these parameters on the number of calorimeter plates and absorber thicknesses was found. The approach is based on careful selection and analysis of the energy spectra obtained by modeling according to the χ-square criterion and an adequate choice of the approximation functions of the energy resolution. The methods proposed in this paper can be easily extended to other combinations of absorber-scintillator thicknesses.

STUDY OF JET ENERGY RESOLUTION AT CDF

The jet energy resolution comes from many sources, which can be grouped into two categories: (1) detector effects such as calorimeter resolution, and (2) physics effects such as fluctuations in the energy outside a clustering cone. For the detector resolution we used both CDF detector simulation and data. For the first time the full granularity of the CDF detector is used to perform corrections at "tower level" rather than at "jet level". The track momenta measured by the Central Tracking Chamber and the neutral cluster energies measured by the Central Shower Max are used to correct the calorimeter tower energies. When tested on γ + jet data, our new algorithm has shown an improvement on the jet energy resolution better than 20% compared to the standard CDF jet corrections.

USING AN ANALOG NEURAL NETWORK TO TRIGGER ON TAU LEPTONS AT CDF

At the Collider Detector at Fermilab (CDF), we have designed and implemented a trigger for tau leptons using analog neural network electronics. Tau leptons offer a fertile area of research both for standard model tests and for new physics searches. Because the bulk of tau leptons decay into hadrons, it is challenging to distinguish them from ordinary hadron jets. Neural networks are well suited to this type of difficult classification problem. In this case, software simulations show that an efficiency of 15% with a rejection factor of 100 could be obtained. The input to the network is a 5×5×2 array of calorimeter tower energies surrounding the seed tower of a cluster. If the network’s single output exceeds a tunable threshold, the event is passed to the next stage of the trigger. An existing system based on the Intel ETANN (Electrically Trainable Analog Neural Network) chip was used to implement the tau lepton neural network trigger. The performance of the trigger in current CDF data will be presented.