KASCADE-Grande Experiment Research Articles

Measuring the radio emission of cosmic ray air showers with LOPES

When ultra high energy cosmic rays hit the atmosphere, they produce a shower of millions of secondary particles. Thereby the charged particles in the shower emit a radio pulse whilst deflected in the Earth's magnetic field. LOPES is a digital antenna array measuring these radio pulses in the frequency range from 40 to 80 MHz. It is located at the site of and triggered by the air shower experiment KASCADE-Grande at Karlsruhe Institute of Technology (KIT), Germany. In its present configuration, it consists of 15 east–west-polarized and 15 north–south-polarized, absolutely calibrated short dipole antennas, as well as 10 LPDAs (with two channels each). Furthermore, it serves as a test bench for technological developments, like new antenna types or a radio-based self-triggering ( LOPES STAR ). To achieve a good angular reconstruction and to digitally form a beam into the arrival direction of the shower, it has a precise time calibration.

WEB based online event displays for KASCADE-grande

For three detector components of the KASCADE-Grande experiment, WEB based online event displays have been implemented. They provide, in a fast and simplified way, actual information about energy deposits and arrival times of measured events, and the overall detector status. Besides the aspect of being able to show air shower events to interested people wherever there is an internet access available, these event displays are an easy and highly useful tool for controlling and maintaining tasks from remote places. The event displays are designed as client-server applications, with the server running as independent part of the local data acquisition. Simplified event data are distributed via socket connections directly to the java applets acting as clients. These clients can run in any common browser on any computer anywhere on the planet.

Status of the KASCADE-Grande experiment

The KASCADE-Grande experiment, located on site of the Forschungszentrum Karlsruhe, Germany, measures extensive air showers in the energy range between 5 × 1014 and 1018 eV, thus covering the first and the possible second knee of cosmic rays. Main goals of the experiment are investigations of the knee at around 4 × 1015 eV and the verification of the existence of an expected "iron knee at energies around 1017 eV. Furthermore, the energy range between 1017 eV and 1018 eV is of special interest since some theories predict that the transition from galactic to extragalactic cosmic rays already begins at these energies. In this overview the apperatus, its performance, and first results are presented.

Time structure of the EAS electron and muon components measured by the KASCADE–Grande experiment

Extensive air showers measured by the KASCADE–Grande experiment at the Forschungszentrum Karlsruhe are studied with respect to the arrival times of electrons and muons at observation level. The mean and the spread of the arrival time distributions have been used to determine the average time profile of the electromagnetic and muonic shower disk. For core distances R > 200 m particles of the muonic shower component arrive on average earlier at observation level than particles of the electromagnetic shower component. The difference increases with the core distance from Δ 〈 t 〉 = ( 12.9 ± 0.2 ) ns at R > 200 m to Δ 〈 t 〉 = ( 47 ± 1 ) ns at R = 500 m , where the width of the muonic and electromagnetic shower disks are comparable. This difference in arrival time is used to separate the electrons and muons dependent on the distance from the shower center. This is intended to be used by experiments with time resolving detectors.

KASCADE-Grande: An overview and first results

The KASCADE-Grande experiment, located at Forschungszentrum Karlsruhe (Germany), is a multi-component extensive air-shower experiment to study cosmic rays and their interactions at primary energies 1014–1018eV. After detailed investigations of the knee in the spectrum with KASCADE and EAS-TOP experiments, the main goal of KASCADE-Grande is to provide conclusive results on the knee region by detecting the expected iron knee in the spectrum at around 1017eV, and measuring the composition in the possible transition region between galactic and extragalactic components. Due to its multi-component characteristics, basically the former KASCADE experiment enriched by two new arrays of scintillator detectors (Grande and Piccolo), with the aim of providing a large acceptance area (0.5km2) and prompt trigger signal, KASCADE-Grande is a suitable array to provide refined measurements in the 1016–1018eV region. In the following, we briefly report on the characteristics of the detector, its performance, and first results based on 2 years of data taking.

Status of the KASCADE-Grande experiment

The KASCADE-Grande experiment measures extensive air showers induced by cosmic rays in the energy range between 0.5 PeV and 1 EeV – the so-called knee region. Principal task of the experiment is to measure with high accuracy the energy and composition of primary cosmic rays to shed light on the nature of the knee. The data of the former KASCADE experiment have been used in a composition analysis showing the knee at 3–5 PeV to be caused by a steepening in the light-element spectra. In the following, an update on these analyses will be given. In addition, the status of the experimental extension – the Grande array – together with first results will be briefly discussed.

Calibrated measurements of the radio emission of cosmic ray air showers

This work investigates the properties of the radio emission of cosmic ray air showers, in particular by reconstructing the lateral distribution of the emission on an event-by-event basis. The LOPES experiment is measuring the radio emission in the frequency range 40-80 MHz in coincidence with the air shower experiment KASCADE-Grande. For the present analysis a set of data is used which was measured with east-west oriented antennas. By selecting the high energy air showers the occurring short radio pulses can be observed and the lateral distribution of the radio signal for individual showers reconstructed. Based on a performed amplitude calibration of the radio signals for each antenna the absolute value of the field strength is known. Therefore the scale parameter R 0 and the field strength 1 ∈0 of the lateral behavior can be determined. The obtained most probable value of the scale parameter results in R 0 ≈ 125 m, and no significant dependence of this values on general shower parameters, like angle-of-incidence or primary energy could be found. A comparison of the field strength ∈ 0 with the value obtained by a parameterization of earlier LOPES measurements yields significant differences, whereby the field strengths determined from lateral distributions are systematically above the values of the parameterization. Using Monte Carlo simulations of the radio emission of extensive air showers, adjusted to the individual measured events by using the known individual shower parameters, direct comparisons with the measurements are performed. As a result of this, a systematically flatter lateral distribution was obtained for the measurements. In particular, measured events with large scale parameter (R 0 > 200 m) could not be reproduced by the simulations. The comparisons of the field strength at different distances with the simulations show a significant discrepancy close to the shower core. This arises from the larger scale parameters at the measurements. However, an important conclusion from the comparison of measurements with simulations results in a deviation of only ≈ 10% of the absolute values of the field strength at a distance of 75 m.

Radio Emission in Atmospheric Air Showers: First Measurements with LOPES-30

When Ultra High Energy Cosmic Rays (UHECR) interact with particles in the Earth's atmosphere, they produce a shower of secondary particles propagating toward the ground. LOPES-30 is an absolutely calibrated array of 30 dipole antennas investigating the radio emission from these showers in detail and clarifying if the technique is useful for large-scale applications. LOPES-30 is co-located and measures in coincidence with the air shower experiment KASCADE-Grande. Status of LOPES-30 and first measurements are presented.

Status of the KASCADE-Grande experiment

The KASCADE-Grande experiment, located at Forschungszentrum Karlsruhe (Germany), is a multi component extensive air-shower experiment dedicated to the study of cosmic-rays and their interactions at primary energies 1014−1018eV. The main goal of the experiment is the detection of the “iron-knee” in the energy spectrum at around 1017 eV, which is expected following the KASCADE and EAS-TOP observations where the positions of the knees of individual mass groups suggest a rigidity dependence. The experiment consists of the former KASCADE (detecting the electromagnetic, the muonic at different energy thresholds and the hadronic components) and Grande, which is an array of plastic scintillators providing a large acceptance area (0.5 km2). In addition the experiment measures in coincidence with the LOPES radio antennas. The experimental set-up, the EAS reconstruction accuracies and first studies, based on 1 year of data taking, are presented.

Radio detection of cosmic rays with LOPES (LOPES Collaboration)

Data taken with a radio antenna array in combination with the ground-level air shower experiment KASCADE-Grande at the Forschungszentrum Karlsruhe open up the possibility to measure large extensive air showers with this new technique. The pulse height of the observed radio signals scales with the primary energy of the particles initiating the air shower. The dependence of the radio signal on the angle of the shower axis with respect to the Earth's geomagnetic field and the coherence of the radiation suggest that the radio signal generation is due to the geosynchrotron mechanism.

Investigating the 2nd knee: The KASCADE-Grande experiment

Recent results from the multi-detector set-up KASCADE on measurements of cosmic rays in the energy range of the so called "first" knee (at ≈ 3 PeV) indicate a distinct knee in the energy spectra of light primary cosmic rays and an increasing dominance of heavy ones towards higher energies. This leads to the expectation of knee-like features of the heavy primaries at around 100 PeV. To investigate this energy region KASCADE has recently been extended by a factor 10 in area to the new experiment KASCADE-Grande. Main results of KASCADE as well as set-up, capabilities, and status of KASCADE-Grande are presented.

Tests of hadronic interaction models by data of the KASCADE-Grande air-shower experiment

KASCADE-Grande is a multi-detector setup to get redundant information on single air shower basis. The information is used to perform multi-parameter analyses to solve the threefold problem of the reconstruction of the unknown primary energy, the primary mass, and to quantify the characteristics of the hadronic interactions in the air-shower development. This contribution discusses the various ways of testing the hadronic interaction mechanisms with data of the original KASCADE experiment and their results, as well as the capabilities in testing the models with the extension of KASCADE, the KASCADE-Grande experiment. Though no hadronic interaction model is fully able to describe the multi-parameter data of KASCADE consistently, the more recent models or improved versions of older models reproduce the data better than a few years ago.

ADVANCED DETECTION METHODS OF RADIO SIGNALS FROM COSMIC RAYS FOR KASCADE GRANDE AND AUGER

The LOPES experiment (LOfar Prototype Station) has been built at the KASCADE-Grande experiment in order to test the LOFAR (LOw Frequency ARray) technology and demonstrate its capability for radio measurements in Extensive Air Showers (EAS). After the first positive results in the framework of the KASCADE-Grande experiment we developed the next generation of antennas, electronics, and trigger. The main new features are easy calibration of antennas with precise detection of polarization, and good capability of self-triggering. The results from this new design are under test in Karlsruhe. Furthermore the background situation was measured and analyzed.

ABSOLUTE CALIBRATION OF THE LOPES ANTENNA SYSTEM

Radio emission in extensive air showers arises from an interaction with the geomagnetic field and is subject of theoretical studies. This radio emission has advantages for the detection of high energy cosmic rays compared to secondary particle or fluorescence measurement methods. Radio antennas like the LOPES30 antenna system are suited to investigate this emission process by detecting the radio pulses. The characteristic observable parameters like electric field strength and pulse length require a calibration which was done with a reference radio source resulting in an amplification factor representing the system behavior in the environment of the KASCADE-Grande experiment. Knowing the amplification factor and the gain of the LOPES antennas LOPES30 is calibrated absolutely for systematic analyses of the radio emission.

COMBINED LOPES AND KASCADE-GRANDE DATA ANALYSIS

First analyses of coincident data of the LOPES (LOfar PrototypE Station) radio antennas with the particle air shower experiment KASCADE-Grande show basic correlations in the observed shower parameters, like the strength of the radio signal and the particle number, or comparing the estimated shower directions. In addition, an improvement of the experimental resolution of the shower parameters reconstructed by KASCADE-Grande can be obtained by including the data of the radio antennas. This important feature will be shown in this article explicitely by an example event.

Results from the KASCADE, KASCADE-Grande, and LOPES experiments

The origin of high-energy cosmic rays in the energy range from 1014 to 1018 eV is explored with the KASCADE and KASCADE-Grande experiments. Radio signals from air showers are measured with the LOPES experiment. An overview on results is given.

The longitudinal development of showers induced by high-energy hadrons in an iron-sampling calorimeter

Occasionally cosmic-ray induced air showers result in single, unaccompanied hadrons at ground level. Such events are investigated with the 300 m2 hadron calorimeter of the KASCADE-Grande experiment. It is an iron sampling calorimeter with a depth of 11 hadronic interaction lengths read out by warm-liquid ionization chambers. The longitudinal shower development is discussed as function of energy up to 30 TeV and the results are compared with simulations using the GEANT/FLUKA code. In addition, results of test measurements at a secondary particle beam of the Super Proton Synchrotron at CERN up to 350 GeV are discussed.

RECONSTRUCTION OF TOTAL MUON NUMBER IN KASCADE-GRANDE

The KASCADE-Grande experiment extends the existing extensive air shower experiment KASCADE by an array of 37 detector stations spread over an area of 0.5 km2. The new Grande array measures the charged component of the showers. To reconstruct the mass composition of the cosmic rays, additional information from the muon component of air showers is required. Using observables from the new Grande array together with the muon detectors of the original KASCADE array provides a possibility to reconstruct also the total muon number of each air shower. The quality of reconstruction based on comparison with simulated data, as well as first results of a reconstructed muon size spectrum are presented.

THE DETECTION OF THE HIGH-ENERGY EAS MUON COMPONENT WITH THE LST DETECTOR OF KASCADE-GRANDE

A Limited Streamer Tube (LST) detector system has been installed at the KASCADE-Grande experiment to study the Extensive Air Showers (EAS) muon component above a threshold of 2.4 GeV. The extended area of 255 m2 of the LST and the fine granularity of detection enables a detailed study of the muon spatial distribution in the very central zone of the air shower. A dedicated, fractal based analysis has been developed to take advantage of the observables of this detector setup. The sensitivity on cosmic rays mass and energy discrimination has been verified, based on 1.5 years of data collection by the KASCADE experiment.

A FADC-based data acquisition system for the KASCADE-grande experiment

We present the design and first test results of a new flash analog-to-digital-converters (FADCs)-based data acquisition (DAQ) system for the Grande array of the KASCADE-Grande experiment. The original KASCADE experiment at the Forschungszentrum Karlsruhe, Germany, has been extended by 37 detector stations of the former EAS-TOP experiment (Grande array) to provide sensitivity to energies of primary particles from the cosmos of up to 1018 eV. The new FADC-based DAQ system will improve the quality of the data taken by the Grande array by digitizing the scintillator signals with a 250-MHz sampling rate. The signals of each of the 37 detector stations are continuously recorded using interleaved 12-bit FADCs located on custom-made digitizer boards at each station. The digitizer boards feature a self-triggering mechanism, initiating the data transmission to the Grande DAQ station using programmable thresholds, a timestamp mechanism, and optical data transmission. The control logic is implemented using field programmable gate arrays (FPGAs). Five optical receiver and temporary storage modules receive the data from up to eight stations each (at an approximate rate of 2.5 MB/s per station) and transfer them into the memory of one of five PCs via a customized PCI interface card. Running on a master PC, the data acquisition software searches for coincidences in the timestamps, incorporates triggers generated by the other KASCADE-Grande components, and builds air shower events from the data of the individual stations. Completed Grande events are sent to the central DAQ of KASCADE-Grande at an approximate rate of a few air shower events per second. Two Grande stations have been equipped with the FADC-based data acquisition system, and first data are shown