Cores Of Extensive Air Showers Research Articles

Core structure of extensive air showers at primary energies around the knee by a multifractal moments analysis

Patterns of particle distributions in the core of extensive air showers, measured by multiwire proportional chambers installed below the central detector of the KASCADE experiment are analysed in terms of multi-fractal moments. Correlating the obtained mass sensitive parameters with the shower size and the number of reconstructed muons in the core region, an artificial neural net analysis leads to probability distributions for associating single showers to particular primary masses. The resulting chemical composition in the energy region of the knee tends to a heavier composition after the knee. The knee position seems to be shifted to higher energies in case of heavy primary cosmic rays.

The investigation of the structure of extensive air shower cores

The experimental results obtained from the Kiel EAS device have been used to investigate the core structure of extensive air showers. An analysis has been made to study the properties of the core of the electromagnetic component as well as the hadron and muon components as measured by the underground neon hodoscope. Muon densities at small distances from the core have been analysed for proton-like and iron-like showers.

Hadron multi-production at the energies 1–10 TeV in the center of mass for colliding nucleons

A steep change of electron, gamma-quanta and hadron energy spectra in the cores of Extensive Air Showers (EAS) at the primary energies about 10 16 eV doesn't correspond to a proposed diffuse change of an energy spectrum and nucleus composition of primary cosmic rays. Resurch of EAS size spectra produced by primary protons and nuclei at different atmosphere depths showed that both: “a break” in EAS spectrum and changes of the energy spectra of particles in EAS cores are the result of the cessation of production of secondary hadrons, energies of which exceed a few tens GeV in the center of mass system of colliding nucleons.

Gamma -ray bundles at the cores of extensive air showers and primary cosmic ray identification.

gamma -ray bundles at the cores of extensive air showers and primary cosmic ray identification.

'Time-track complementarity' in the study of EAS longitudinal development

Extensive air shower (EAS) muon production and propagation through the atmosphere were simulated. The incidence angles and arrival time at the observation level were determined for each muon. It is shown that for large distances from EAS cores and for GeV-muons, time and track measurements could be used complementarily to improve the accuracy of the muon production height determination. For TTC detectors of 5 GeV muons attached to EAS arrays at mountains and placed at a distance of about 200-250 m from its centre, the accuracy of the muon production depth estimate is about 35 g cm-2. The influence of the detector location, the muon energy threshold, the observation level and experimental errors is analysed.

Fractal and factorial studies of electron density distributions in extensive air showers

For years there has been a problem in cosmic ray studies of how to distinguish cascades originated by primary photons from extensive air showers (EAS) originated by primary protons or heavy nuclei. In this paper it is suggested that the investigations of factorial moments and multifractal structures of the density fluctuations of charged particles near EAS cores can solve the problem in question. The study of f( alpha )- alpha spectra seems to give us a chance of distinguishing the iron-originated EAS from the proton-initiated ones.

On the energy estimation of ultra-high-energy cosmic rays observed with the surface detector array

A Monte Carlo simulation has been carried out to look for a suitable parameter as the energy estimator for large extensive air showers (EAS) at Akeno. For primaries of fixed energy, the fluctuation of the electron density at several hundred metres from the EAS core is smaller than that near the core, as has been pointed out by Hillas et al. (1971). The present simulation shows that the fluctuation of the electron density at 600 m (S(600)) from the core is within 20%, irrespective of the primary composition, for zenith angles less than 35 degrees and primary energies above 1018 eV. The conversion factor from S(600) to the primary energy is independent of primary composition and interaction models within a certain zenith angle (<or=35 degrees ), but depends on the lateral distribution function of electrons. By using the interaction model (QCD) and the lateral distribution function which give the best fit to Akeno experimental data, the conversion factor at Akeno level (920 g cm-2) is E0(eV)=(2.03+or-0.10)*1017 S(600)1.02+or-0.02 for vertical showers with energy greater than 1017 eV.

Delayed energetic events in extensive air showers

Production of massive (\ensuremath{\ge} 10 GeV/${\mathit{c}}^{2}$) strongly interacting particles in very-high-energy interactions has been suggested by many theories. These particles, if produced in the cores of extensive air showers in the upper atmosphere, would arrive at the observational level delayed by tens of nanoseconds relative to all other known particles of similar energy, provided they are relatively stable (lifetime &gt; ${10}^{\ensuremath{-}6}$ s). Experiments searching for such particles have reported observing delayed (&gt;20 ns) energetic (&gt;40 GeV) events. However several anomalous features observed for these events have precluded their interpretation in terms of massive particles with ordinary hadronic interaction characteristics in a conclusive manner. We report here the details of a new experiment carried out at the Ooty laboratory during 1978-1981 where we have attempted to study the delayed energetic events with a multidetector system placed inside the large Ooty multiplate cloud chamber. Our observations show that the delayed energetic events could not be ascribed to high-energy hadronlike interactions of a massive strongly interacting particle. We have observed one delayed event showing a high-energy cascade in cloud chamber but inadequate timing information does not make a convincing case for this event to be due to a high-energy delayed massive hadron. However this event combined with observation of two similar events earlier by Tonwar et al. suggest the existence of some interesting phenomenon requiring observations over a long period of time. We have obtained a 99%-C.L. upper limit of 1.7\ifmmode\times\else\texttimes\fi{}${10}^{\ensuremath{-}11}$ ${\mathrm{cm}}^{\ensuremath{-}2}$ ${\mathrm{s}}^{\ensuremath{-}1}$ ${\mathrm{sr}}^{\ensuremath{-}1}$ for the flux of massive particles in extensive air showers of size \ensuremath{\sim}(5\ifmmode\times\else\texttimes\fi{}${10}^{4}$)-(5\ifmmode\times\else\texttimes\fi{}${10}^{6}$) particles which corresponds to an upper limit of 2.5\ifmmode\times\else\texttimes\fi{}${10}^{\ensuremath{-}33}$ ${\mathrm{cm}}^{2}$ for the production cross section for particles of mass &gt; 10 GeV/${\mathit{c}}^{2}$ at energies of \ensuremath{\sim}${10}^{5}$-${10}^{7}$ GeV.

The effects of large extensive air showers on the Earth's atmospheric electric field

Data have been obtained which suggest that changes in the Earth's electric field of 10–20 V m −1 occur close to the cores of extensive air showers initiated by primary particles of energy ≳10 17eV. Such changes are detectable using simple equipment in fair weather conditions.

Flash tube hodoscopes for particle density measurements

Details on the construction and the performance characteristics of a 31 m 2 neon hodoscope are presented. The detector is in operation at Kiel since 1965 investigating the density distribution of charged particles in the cores of extensive air showers. It is shown that a device of this type meets most of the requirements for a large area detector in cosmic ray work.

Search for massive interacting particles near the cores of extensive air showers of energies of about 2×1014-1016eV

An experiment carried out at mountain altitude to study the time structure of hadrons in extensive air showers has revealed the existence of a special class of delayed high energy interacting particles at distances less than 20 m from the axes of showers of energy greater than 2*1014 eV. These particles having energies more than 20 GeV and delays more than 20 ns relative to the air shower front, constitute about 0.5% of the hadrons of similar energy. Detailed calculations predict the frequency of events with such delay-energy characteristics to be less than 10-4 if they are due to known hadrons like nucleons and pions. The high energy large delay events however can be understood if there exist particles much heavier than nucleons (mass >10 GeV/c2) which are produced in ultrahigh energy interactions. Under certain circumstances the flux of such massive interacting particles has been deduced from the experimental data as approximately 10-9 cm-2 s-1 sr-1.

13.—A Search for the Quark in Extensive Air Showers, using a Counter-controlled Cloud Chamber

SynopsisA search is reported for the relativistic e/3 quark among the cores of Extensive Air Showers initiated by primaries with energies greater than 1014 eV. The detector is a high-pressure cloud chamber filled with helium at 28 atmospheres, and is counter controlled. The experimental conditions avoid the criticisms levelled at the McCusker experiment and are such that the tracks of e/3 quarks cannot be simulated by singly charged shower particles either through statistical variations in primary ionisation or otherwise. The primary ionisation density, measured using a gap-counting technique on post-expansion electron and muon tracks, is compared with predictions from the theory of Budini et al. (1960). The agreement achieved shows that the theory is a reliable foundation for methods of identifying quark candidates, and measuring charges. The experiment has been running for 5000 hours. No quark candidates have been found. With an acceptance angle of 0·3 sr and an area of 140 cm2, this sets the upper limit of flux of e/3 quarks at 4 × 10−9 cm−2 sec−1 sr−1 with 95 per cent, confidence. The experiment is being continued.

Muon bundles in large EAS

The Nottingham muon detector at Haverah Park has shown up events which contained an unexpected close grouping of muons at large distances from the cores of extensive air showers (EAS). This paper is concerned with the detailed analysis of these events. The results are considered in relation to similar groupings observed near the core of showers by the Moscow State University group.

New studies of Čerenkov radiation in extensive air showers

New experimental studies of the angular, spectral and temporal properties of Cerenkov light produced in cosmic-ray extensive air showers (EAS) are reported. These data appear to be best explained by a two-component model for the origin of the Cerenkov light with production occurring not only (predominantly) at the electron maximum but also at greater atmospheric depths from unscattered, nearly «onaxis» particles, such as expected in the EAS core. Monte Carlo calculations to be published of EAS cores support this hypothesis. An individual EAS may thus be detected at its maximum of electromagnetic development and at its core simultaneously. New experiments employing these techniques are discussed and the important implications for the possible identification of the primary particle initiating the EAS detected are considered. Experiments are now in progress using the methods reported here to search for cosmic γ-ray sources as well as to study the primary cosmic-ray mass spectrum at energiesE0⋧1012eV.

Lateral distribution of the muon component in the central region of extensive air showers

Using a new device for extensive air shower core localization consisting of four sets of Conversi neon detectors of total area 9 m2 (comprising 36000 neon tubes), cores have been located with high accuracy and the lateral muon distribution and density have been measured for a threshold energy of 0.6 GeV. The interpretation of the shape of this distribution is discussed and compared with theoretical calculations. As the muon lateral distribution is mainly determined by the angles of emission of parent pions, some features of the distribution of transverse momenta pt of pions produced in air can be analysed. For low pt values a discrepancy is found with the Cocconi empirical pt distribution which comes from accelerator data. A flattening of the muons' lateral distribution near the shower axis is interpreted as being due to a lack of small pt values.

Methode de digitalisation des densities electroniques des grandes gerbes AU Moyen de detecteurs a scintillations de grandes surfaces. application a la localisation des centeres

We describe a new method to digitalize electron densities of extensive air showers. The density measurements are made by a group of 7 scintillation detectors each of 1 m 2 and covering an area of 1200 m 2. Each detector is associated with a logic circuit to digitalize the pulse heights. The immediate application of this method is the location of the core of extensive air showers (E≧10 15 eV) .

Electron-photon energies in extensive air showers

Average electron and photon energies are found at various distances from the cores of extensive air showers by comparing the multiplicities produced under different thicknesses of lead and of water absorbers as measured through the use of two large scintillators. For distances from 2.3·10−2 to 1.4·10−1 shower units from the cores of showers of 105 to 107 particles the total energy carried by electrons and photons per electron is found to be 61(r/r2)−0.74 MeV per electron. The ratio of the average photon energy to the average electron energy is found to vary from 1.5 to 3.3 at different distances. Transition curves obtained with different thicknesses of water as absorber are used to show that for showers of 4.6·104 particles a total of 1.5·1012 eV is expended in the production of pions per nuclear interaction to give an inelasticity of 0.33.

Zenith angle distribution of extensive air showers

Electron tracks obtained in a cloud chamber triggered by a large scintillator are analysed to obtain the zenith angle dependence of the cores of extensive air showers. A cosine power law gives a reasonable fit with an an exponent of 7.6. A better fit is obtained using the exponential absorption law exp [−(x 0/λ)(sec θ −1)]. Fitting the moments of the observed angles to this distribution leads to a value of the absorption length λ=144 g/cm2. These results apply at 1575 m s.l. and for showers of 105 to 106 particles.

The Lateral Structure of Cosmic Ray Extensive Air Showers at Sea Level

The axes or cores of extensive air showers have been selected by observing in a cloud chamber cascade showers produced by a single high-energy (>5 × 109 eV) electron or photon, and an upper limit of 5 m for the spread of such particles has been found. By placing trays of hodoscoped counters at various distances from this core selector it has been possible to determine the relation between density of ionizing particles and distance from the axis for showers of approximately 104-105 particles. The experimental arrangement and method of analysis used have certain advantages over those employed by other workers. It is concluded that although the results of the present experiment and those of other workers are consistent with the Moliere structure function, not too much weight should be placed on this agreement.

On the interaction of cosmic rays with matter under 50 metres water equivalent

The production of penetrating secondaries by cosmic rays at 50 m w.e. has been investigated by means of a counter hodoscope. The cross section (in lead) for events which can be interpreted as pairs of associated penetrating particles (a.p.p.) is not larger than (13±3)·10−30 cm2/nucleon. Such a value is deduced from measurements of the corresponding differential cross section as a function of the penetration of the secondary particles produced (section 4·3 table V). A value of the same order of magnitude is found for the production ofa.p.p. in rock (section 4·5). Furthermore it is shown that the events that can be interpreted as showers penetrating 15 cm Pb, have a frequency that can be explained, at least in part, as due to purely electromagnetic interaction. Therefore one can establish an upper limit of a few units in 10−30 cm2/nucleon for the cross section for production in Pb of penetrating showers by μ-mesons. Finally we discuss those events which appear to be due to a few penetrating particles coming from the rock and it is shown that they can be accounted for, by considering besides the production of penetrating showers in rock the penetrating particles present in the vicinity of the core of extensive air showers.