The spatial distribution of Cherenkov radiation from cascade showers generated by muons in water has been measured with Cherenkov water calorimeter (CWC) NEVOD. This result allowed to improve the techniques of treating cascade showers with unknown axes by means of CWC response analysis. The techniques of selecting the events with high energy cascade showers and reconstructing their parameters are discussed. Preliminary results of measurements of the spectrum of cascade showers in the energy range 100 GeV - 20 TeV generated by cosmic ray muons at large zenith angles and their comparison with expectation are presented.
In the present work we carry out a study of the high energy cosmic rays mass identification capabilities of a hybrid detector employing both fluorescence telescopes and particle detectors at ground using simulated data. It involves the analysis of ex
tensive showers with zenith angles above 60 degrees making use of the joint distribution of the depth of maximum and muon size at ground level as mass discriminating parameters. The correlation and sensitivity to the primary mass are investigated. Two different techniques - clustering algorithms and neural networks - are adopted to classify the mass identity on an event-by-event basis. Typical results for the achieved performance of identification are reported and discussed. The analysis can be extended in a very straightforward way to vertical showers or can be complemented with additional discriminating observables coming from different types of detectors.
The current methods to determine the primary energy of ultra-high energy cosmic rays (UHECRs) are different when dealing with hadron or photon primaries. The current experiments combine two different techniques, an array of surface detectors and fluo
rescence telescopes. The latter allow an almost calorimetric measurement of the primary energy. Thus, hadron-initiated showers detected by both type of detectors are used to calibrate the energy estimator from the surface array (usually the interpolated signal at a certain distance from the shower core S(r0)) with the primary energy. On the other hand, this calibration is not feasible when searching for photon primaries since no high energy photon has been unambiguously detected so far. Therefore, pure Monte Carlo parametrizations are used instead. In this work, we present a new method to determine the primary energy of hadron-induced showers in a hybrid experiment based on a technique previously developed for photon primaries. It consists on a set of calibration curves that relate the surface energy estimator, S(r0), and the depth of maximum development of the shower, Xmax, obtained from the fluorescence telescopes. Then, the primary energy can be determined from pure surface information since S(r0) and the zenith angle of the incoming shower are only needed. Considering a mixed sample of ultra-high energy proton and iron primaries and taking into account the reconstruction uncertainties and shower to shower fluctuations, we demonstrate that the primary energy may be determined with a systematic uncertainty below 1% and resolution around 16% in the energy range from 10^{18.5} to 10^{19.6} eV. Several array geometries, the shape of the energy error distributions and the uncertainties due to the unknown composition of the primary flux have been analyzed as well.
One of the uncertainties in interpretation of ultra-high energy cosmic ray (UHECR) data comes from the hadronic interaction models used for air shower Monte Carlo (MC) simulations. The number of muons observed at the ground from UHECR-induced air sho
wers is expected to depend upon the hadronic interaction model. One may therefore test the hadronic interaction models by comparing the measured number of muons with the MC prediction. In this paper, we present the results of studies of muon densities in UHE extensive air showers obtained by analyzing the signal of surface detector stations which should have high $it{muon , purity}$. The muon purity of a station will depend on both the inclination of the shower and the relative position of the station. In 7 years data from the Telescope Array experiment, we find that the number of particles observed for signals with an expected muon purity of $sim$65% at a lateral distance of 2000 m from the shower core is $1.72 pm 0.10{rm (stat.)} pm 0.37 {rm (syst.)}$ times larger than the MC prediction value using the QGSJET II-03 model for proton-induced showers. A similar effect is also seen in comparisons with other hadronic models such as QGSJET II-04, which shows a $1.67 pm 0.10 pm 0.36$ excess. We also studied the dependence of these excesses on lateral distances and found a slower decrease of the lateral distribution of muons in the data as compared to the MC, causing larger discrepancy at larger lateral distances.
Large High Altitude Air Shower Observatory(LHAASO) is a composite cosmic ray observatory consisting of three detector arrays: kilometer square array (KM2A) which includes the electromagnetic detector array and muon detector array, water Cherenkov det
ector array (WCDA) and wide field of view Cherenkov telescope array (WFCTA). One of the main scientific objectives of LHAASO is to precisely measure the cosmic rays energy spectrum of individual components from 1014 eV to 1018 eV. The hybrid observation will be employed by LHAASO experiment, in which the lateral and longitudinal distributions of the extensive air shower can be observed simultaneously. Thus many kinds of parameters can be used for primary nuclei identification. In this paper, high purity cosmic ray simulation samples of light nuclei component are obtained through Multi-Variable Analysis. The apertures of 1/4 LHAASO array for pure proton and mixed proton and helium (H&He) samples are 900 m2Sr and 1800 m2Sr respectively. A prospect of proton and H&He spectra from 100 TeV to 4 PeV is discussed.
The NUCLEON experiment is designed to measure chemical composition of cosmic rays with charges from Z=1 to 30 in an energy region from 5*10^11 to 10^15 eV. In this article the data analysis algorithm and spectra of Ni and Fe nuclei, measured in the NUCLEON experiment, are presented.
R.P. Kokoulin
,N.S. Barbashina
,A.G. Bogdanov
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(2017)
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"Energy spectrum of cascade showers generated by cosmic ray muons in water"
.
Khomyakov Vasiliy Mr.
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