Hadronic Showers Research Articles

A simulation study on few parameters of Cherenkov photons in extensive air showers of different primaries incident at various zenith angles over a high altitude observation level

We have studied the distribution patterns of lateral density, arrival time and angular position of Cherenkov photons generated in Extensive Air Showers (EASs) initiated by γ-ray, proton and iron primaries incident with various energies and at various zenith angles. This study is the extension of our earlier work [1] to cover a wide energy range of ground based γ-ray astronomy with a wide range of zenith angles (≤40°) of primary particles, as well as the extension to study the angular distribution patterns of Cherenkov photons in EASs. This type of study is important for distinguishing the γ-ray initiated showers from the hadronic showers in the ground based γ-ray astronomy, where Atmospheric Cherenkov Technique (ACT) is being used. Importantly, such study gives an insight on the nature of γ-ray and hadronic showers in general. In this work, the CORSIKA 6.990 simulation code is used for generation of EASs. Similarly to the case of Ref. [1], this study also revealed that, the lateral density and arrival time distributions of Cherenkov photons vary almost in accordance with the functions: ρch(r)=ρ0e−βr and tch(r)=t0eΓ/rλ respectively by taking different values of the parameters of functions for the type, energy and zenith angle of the primary particle. The distribution of Cherenkov photon’s angular positions with respect to shower axis shows distinctive features depending on the primary type, its energy and the zenith angle. As a whole this distribution pattern for the iron primary is noticeably different from those for γ-ray and proton primaries. The value of the angular position at which the maximum number of Cherenkov photons are concentrated, increases with increase in energy of vertically incident primary, but for inclined primary it lies within a small value (≤1°) for almost all energies and primary types. No significant difference in the results obtained by using the high energy hadronic interaction models, viz., QGSJETII and EPOS has been observed.

Dual-readout calorimetry: recent results from RD52 and plans for experiments at future e+e− colliders

The Dual-Readout calorimetry, developed to overcome the main limiting factor in hadronic energy measurements, has been thoroughly investigated by the DREAM/RD52 collaboration during the last 15 years. The latest results show that very interesting performance may be obtained for both e.m. and hadronic showers, together with excellent standalone e/pi separation. These results and the plans (and the expected performance) for dual-readout calorimetry in the CepC/FCC-ee environment, are presented and discussed.

Revisiting big-bang nucleosynthesis constraints on long-lived decaying particles

We study effects of long-lived massive particles, which decay during the big-bang nucleosynthesis (BBN) epoch, on the primordial abundances of light elements. Compared to the previous studies, (i) the reaction rates of the standard BBN reactions are updated, (ii) the most recent observational data of light element abundances and cosmological parameters are used, (iii) the effects of the interconversion of energetic nucleons at the time of inelastic scatterings with background nuclei are considered, and (iv) the effects of the hadronic shower induced by energetic high energy anti-nucleons are included. We compare the theoretical predictions on the primordial abundances of light elements with latest observational constraints, and derive upper bounds on relic abundance of the decaying particle as a function of its lifetime. We also apply our analysis to unstable gravitino, the superpartner of the graviton in supersymmetric theories, and obtain constraints on the reheating temperature after inflation.

Testbeam performance of a shashlik calorimeter with fine-grained longitudinal segmentation

An iron- plastic-scintillator shashlik calorimeter with a 4.3 X0 longitudinal segmentation was tested in November 2016 at the CERN East Area facility with charged particles up to 5 GeV . The performance of this detector in terms of electron energy resolution, linearity, response to muons and hadron showers are presented in this paper and compared with simulation. Such a fine-grained longitudinal segmentation is achieved using a very compact light readout system developed by the SCENTT and ENUBET Collaborations, which is based on fiber-SiPM coupling boards embedded in the bulk of the detector. We demonstrate that this system fulfills the requirements for neutrino physics applications and discuss performance and additional improvements.

An Algorithm for the Reconstruction of Neutrino-induced Showers in the ANTARES Neutrino Telescope

Abstract Muons created by charged current (CC) interactions in the water surrounding the ANTARES neutrino telescope have been almost exclusively used so far in searches for cosmic neutrino sources. Due to their long range, highly energetic muons inducing Cherenkov radiation in the water are reconstructed with dedicated algorithms that allow for the determination of the parent neutrino direction with a median angular resolution of about 0.°4 for an neutrino spectrum. In this paper, an algorithm optimized for accurate reconstruction of energy and direction of shower events in the ANTARES detector is presented. Hadronic showers of electrically charged particles are produced by the disintegration of the nucleus both in CC and neutral current interactions of neutrinos in water. In addition, electromagnetic showers result from the CC interactions of electron neutrinos while the decay of a tau lepton produced in CC interactions will, in most cases, lead to either a hadronic or an electromagnetic shower. A shower can be approximated as a point source of photons. With the presented method, the shower position is reconstructed with a precision of about 1 m; the neutrino direction is reconstructed with a median angular resolution between 2° and 3° in the energy range of 1–1000 TeV. In this energy interval, the uncertainty on the reconstructed neutrino energy is about 5%–10%. The increase in the detector sensitivity due to the use of additional information from shower events in the searches for a cosmic neutrino flux is also presented.

Nature of the low-energy, γ-like background for the Cherenkov Telescope Array

The upcoming Cherenkov Telescope Array (CTA) project is expected to provide unprecedented sensitivity in the low-energy ( ≲ 100 GeV) range for Cherenkov telescopes. Most of the remaining background in this energy range results from misidentified hadron showers. In order to fully exploit the potential of the telescope systems it is worthwhile to look for ways to further improve the available analysis methods for γ/hadron separation. We study the composition of the background for the planned CTA-North array by identifying events composed mostly of a single electromagnetic subcascade or double subcascade from a π0 (or another neutral meson) decay. We apply the standard simulation chain and state-of-the-art analysis chain of CTA to evaluate the potential of the standard analysis to reject such events. Simulations show a dominant role of such single subcascade background for CTA up to energies ∼ 70 GeV. We show that a natural way of rejection of such events stems from a shifted location of the shower maximum, and that the standard stereo reconstruction method used by CTA already exploits most of expected separation.

The NA62 Hadron Calorimeter

NA62 is a fixed target experiment located in the north area of CERN. The ambitious aim of the experiment is the measurement of the branching ratio (Br) of the very rare decay within 10% precision using a decay-in-flight technique. The branching ratio of this decay is very well calculated in the standard model as (9.11 ± 0.72) × 1011 and the measurement of this channel represents one of the most promising fields for the search of new physics beyond the standard model. The presence of just one detectable track in the final state is an enormous challenge for any experiment. The decay is fully reconstructed, which leads to a strong background suppression. Still the detector resolution, combined with the tiny branching ratio of the signal, makes the K+ → μ+ν decay (whose Br is 0.64) a critical source of background. The NA62 detector was therefore designed to perform an excellent π/μ separation using a very efficient particle identification system. A major role is played by the calorimeters that provides a muon rejection factor of the order of 105 through the measurement of energy and shape of the hadronic showers. The calorimetric system consists of an electromagnetic calorimeter filled with liquid krypton and a hadron calorimeter. This presentation, after illustrating the HAC structure, reports on the calibration procedure of the detector response and preliminary results of the performance of the hadronic energy reconstruction.

Hadrons in the CALICE silicon-tungsten electromagnetic calorimeter

A detailed study of hadronic interactions is presented using data recorded with the highly granular CALICE silicon-tungsten electromagnetic calorimeter. The predictions of several Monte Carlo Geant4 models are compared with experimental data, taken at FNAL in 2008. The contribution recaps results published in 2015 and a set of new results available since the beginning of 2016. The published results present a detailed analysis of hadronic showers in terms of radial and longitudinal hit and energy distributions. For the most recent analysis a simple track-finding algorithm was developed to study tracks left by secondary particles, emerging from hadronic interactions in the highly granular electromagnetic calorimeter prototype. Present Monte Carlo simulations provide a good description of the experimental data in terms of new observables, available through the detailed analysis of secondary particles; the Monte Carlo predictions are within 20% of the data, and for many observables much closer.

On the energy spectrum of cosmogenic neutrons

The processes of the generation of cosmogenic neutrons (cg-neutrons) underground are considered. The neutrons produced by cosmic-ray muons in their interactions with matter are called cosmogenic. Deep-inelastic ${\pi}A$-collisions of pions in muon-induced hadronic showers are mainly their source at energies above 30 MeV. The characteristics of the energy spectrum for the generation of cg-neutrons have been determined by invoking the additive quark model of deep-inelastic soft processes and the mechanism for the interactions of high-energy nucleons in a nucleus. The three-component shape of the spectrum is explained, and the energy of the "knee" in the spectrum has been found to depend on the mass number $A$. The peculiarities of deep-inelastic ${\pi}A$-scattering lead to the conclusion that the spectrum of cg-neutrons steepens sharply at energies above 1 GeV. The calculated quantitative characteristics of the spectrum are compared with those obtained in measurements.

Software compensation in particle flow reconstruction

The particle flow approach to calorimetry benefits from highly granular calorimeters and sophisticated software algorithms in order to reconstruct and identify individual particles in complex event topologies. The high spatial granularity, together with analogue energy information, can be further exploited in software compensation. In this approach, the local energy density is used to discriminate electromagnetic and purely hadronic sub-showers within hadron showers in the detector to improve the energy resolution for single particles by correcting for the intrinsic non-compensation of the calorimeter system. This improvement in the single particle energy resolution also results in a better overall jet energy resolution by improving the energy measurement of identified neutral hadrons and improvements in the pattern recognition stage by a more accurate matching of calorimeter energies to tracker measurements. This paper describes the software compensation technique and its implementation in particle flow reconstruction with the Pandora Particle Flow Algorithm (PandoraPFA). The impact of software compensation on the choice of optimal transverse granularity for the analogue hadronic calorimeter option of the International Large Detector (ILD) concept is also discussed.

Measurement of meson resonance production in pi ^-+ C interactions at SPS energies

We present measurements of rho ^0, omega and K^{*0} spectra in pi ^{-} + C production interactions at 158 text{ GeV }{/}text{ c } and rho ^0 spectra at 350 text{ GeV }{/}text{ c } using the NA61/SHINE spectrometer at the CERN SPS. Spectra are presented as a function of the Feynman’s variable x_text {F} in the range 0< x_text {F} < 1 and 0< x_text {F} < 0.5 for 158 and 350 text{ GeV }{/}text{ c } respectively. Furthermore, we show comparisons with previous measurements and predictions of several hadronic interaction models. These measurements are essential for a better understanding of hadronic shower development and for improving the modeling of cosmic ray air showers.

MAGIC gamma-ray telescopes hunting for neutrinos and their sources

The discovery of an astrophysical flux of high-energy neutrinos by the IceCube Collaboration marks a major breakthrough in the ongoing search for the origin of cosmic rays. Presumably, the neutrinos, together with gamma rays, result from pion decay, following hadronic interactions of protons accelerated in astrophysical objects to ultra-relativistic energies. So far, the neutrino sky map shows no significant indication of astrophysical sources. Here, we report first results from follow-up observations, of sky regions where IceCube has detected muon tracks from energetic neutrinos, using the MAGIC telescopes which are sensitive to gamma rays at TeV energies. Furthermore, we show that MAGIC has the potential to distinguish air showers induced by tau neutrinos from the background of hadronic showers in the PeV-EeV energy range, employing a novel analysis method to the data obtained with high-zenith angle observations.

Topological cell clustering in the ATLAS calorimeters and its performance in LHC Run 1

The reconstruction of the signal from hadrons and jets emerging from the proton–proton collisions at the Large Hadron Collider (LHC) and entering the ATLAS calorimeters is based on a three-dimensional topological clustering of individual calorimeter cell signals. The cluster formation follows cell signal-significance patterns generated by electromagnetic and hadronic showers. In this, the clustering algorithm implicitly performs a topological noise suppression by removing cells with insignificant signals which are not in close proximity to cells with significant signals. The resulting topological cell clusters have shape and location information, which is exploited to apply a local energy calibration and corrections depending on the nature of the cluster. Topological cell clustering is established as a well-performing calorimeter signal definition for jet and missing transverse momentum reconstruction in ATLAS.

Initial performance studies of a general-purpose detector for multi-TeV physics at a 100 TeV pp collider

This paper describes simulations of detector response to multi-TeV particles and jets at the Future Circular Collider (FCC-hh) or Super proton-proton Collider (SppC) which aim to collide proton beams with a centre-of-mass energy of 100 TeV. The unprecedented energy regime of these future experiments imposes new requirements on detector technologies which can be studied using the detailed GEANT4 simulations presented in this paper. The initial performance of a detector designed for physics studies at the FCC-hh or SppC experiments is described with an emphasis on measurements of single particles up to 33 TeV in transverse momentum. The reconstruction of hadronic jets has also been studied in the transverse momentum range from 50 GeV to 26 TeV. The granularity requirements for calorimetry are investigated using the two-particle spatial resolution achieved for hadron showers.

Highly granular calorimeters: technologies and results

The CALICE collaboration is developing highly granular calorimeters for experiments at a future lepton collider primarily to establish technologies for particle flow event reconstruction. These technologies also find applications elsewhere, such as detector upgrades for the LHC. Meanwhile, the large data sets collected in an extensive series of beam tests have enabled detailed studies of the properties of hadronic showers in calorimeter systems, resulting in improved simulation models and development of sophisticated reconstruction techniques. In this proceeding, highlights are included from studies of the structure of hadronic showers and results on reconstruction techniques for imaging calorimetry. In addition, current R&D activities within CALICE are summarized, focusing on technological prototypes that address challenges from full detector system integration and production techniques amenable to mass production for electromagnetic and hadronic calorimeters based on silicon, scintillator, and gas techniques.

Tracking within Hadronic Showers in the CALICE SDHCAL prototype using a Hough Transform Technique

The high granularity of the CALICE Semi-Digital Hadronic CALorimeter (SDHCAL) provides the capability to reveal the track segments present in hadronic showers. These segments are then used as a tool to probe the behaviour of the active layers in situ, to better reconstruct the energy of these hadronic showers and also to distinguish them from electromagnetic ones. In addition, the comparison of these track segments in data and the simulation helps to discriminate among the different shower models used in the simulation. To extract the track segments in the showers recorded in the SDHCAL, a Hough Transform is used after being adapted to the presence of the dense core of the hadronic showers and the SDHCAL active medium structure.

Shashlik Calorimeters With Embedded SiPMs for Longitudinal Segmentation

Effective longitudinal segmentation of shashlik calorimeters can be achieved taking advantage of the compactness and reliability of silicon photomultipliers. These photosensors can be embedded in the bulk of the calorimeter and are employed to design very compact shashlik modules that sample electromagnetic and hadronic showers every few radiation lengths. In this paper, we discuss the performance of a calorimeter made up of 12 such modules and able to sample showers every $\sim 4X_{0}$ . In summer 2016, this prototype has been exposed to electrons, muons, and hadrons at CERN PS (East Area T9 beamline). The performances in terms of energy resolution, linearity, response to minimum ionizing particles, and reconstruction of the shower profile are discussed.

Studying depth of shower maximum using variable interaction length

Due to the high energy interactions of cosmic ray particles, progressive showers of secondary particles initiate in the atmosphere. Several models are suggested to describe the longitudinal development of extensive air showers, for example the Heitler model. The Heitler model also is written for hadronic showers. Anyhow, the predicted values of $X_{max}$ may differ significantly with the values from detailed simulations by up to about $100~(\mbox{g}/\mbox{cm}^{2})$ . In the present work, the mean depth of shower maximum is calculated using a variable interaction length. New equations for $X_{max} $ in the electromagnetic and hadronic showers have been obtained.

High energy γ-ray detection with the AMS-02 electromagnetic calorimeter

The electromagnetic Calorimeter (ECAL) of the AMS-02 experiment is a fine grained lead-scintillating fibers sampling calorimeter that allows for a precise 3-dimensional imaging of the longitudinal and lateral developement of electromagnetic showers. With a total thickness of 17X0, electromagnetic showers are well contained and the energy resolution is 2% up to 1TeV. ECAL provides a high discrimination between electromagnetic and hadronic showers; furthermore, together with the rest of the AMS-02 detector, it is able to identify the subdominant (≃10−6) photon flux from GeV up to TeV energies. Thanks to its high granularity ECAL has an excellent pointing capability (0.5o at high energies) that offers an unusual possibility of drawing sky maps with the calorimeter standalone.

Classification of high-energy antiprotons on electrons background based on calorimeter data in PAMELA experiment

In modern experimental physics a heterogeneous coordinate-sensitive calorimeters are widely used due to their good characteristics and possibilities to obtain a three-dimensional information of particles interactions. Especially it is important at high-energies when electromagnetic or hadron showers are arise. We propose a quit efficient method to identify antiprotons (positrons) with energies more than 10 GeV on electron (proton) background by calorimeter of such kind. We construct the AdaBoost classifier and SVM to separate particles into two classes, different combinations of energy release along reconstructed particle trajectory were used as feature vector. We test a preliminary version of the method on a calorimeter of the PAMELA magnetic spectrometer. For high-energy particles we got a good quality of classification: it lost about 5 · 10−2 of antiprotons, and less than 4 · 10−4 of electrons were classified to antiproton class.