EAS Components Research Articles

How should we modify the high energy interaction models?

An analysis has been made of the present situation with respect to the high energy hadron-nucleus and nucleusnucleus interaction models as applied to cosmic rays. As is already known, there are inconsistencies in the interpretation of experimental data on the primary mass composition, which appear when different EAS components are used for the analyses, even for the same experiment. In the absence of obvious experimental defects, there is a clear need for an improvement to the existing models; we argue that the most promising way is to enlist two effects which should be present in nucleus-nucleus collisions but have not been allowed for before. These are: a few percent energy transfer into the EAS electromagnetic component due to electron-positron pair production or electromagnetic radiation of the quark-gluon plasma and a small slow-down of the cascading process in its initial stages associated with the extended lifetime of excited nuclear fragments. The latter process displaces the shower maximum deeper into the atmosphere.

Problem of the knee in the cosmic ray energy spectrum and experimental data concerning the knees for different EAS components

The behaviour of the primary cosmic ray composition near the knee may be considered as being of fundamental importance in studies of the knee nature. In this paper experimental data obtained with the KASCADE array are considered and patterns of the knees in electron and muon size spectra are compared. Such a comparision provides valuable information to check the consistency of the existing experimental data and model predictions. Improvements in the existing simulation methods are essential to ultimately establish the results of the KASCADE mass composition studies. Evidently some revision of hadronic interaction models is needed to eliminate the discrepancy between mass compositions derived with and without KASCADE hadronic calorimeter data.

Properties of cosmic ray interactions at PeV energies

An analysis has been made of the present situation with the high energy hadron–nucleus and nucleus–nucleus interaction models. As is already known there are inconsistencies in the interpretation of experimental data on the primary mass composition, which appear when different EAS components are used for the analyses, even for the same experiment. In the absence of obvious experimental defects, there is a clear need for an improvement to the existing models; we argue that the most promising way is to introduce two effects which should be present in nucleus–nucleus collisions and have not been allowed for before. These are: a few percent energy transfer into the EAS electromagnetic component due to electron–positron pair production or electromagnetic radiation of quark-gluon plasma and a small slow-down of the cascading process in its initial stages associated with the extended lifetime of excited nuclear fragments. The latter process displaces the shower maximum deeper into the atmosphere.

Studies on pour point depression of EVA polymers in solvent mixtures containing wax

AbstractMeasurements of the change of the pour point depression (ΔTPP) were performed for the wax solutions made of four solvent mixtures: ethyl acetate/hexane (EA/HEX), 1,2‐dichloroethane/cyclohexane (DCE/CYH), butanone/heptane (MEK/HEP), and acetone/chloroform (AC/CF) doped with EVA polymers. The values of ΔTPP increase significantly with increasing of the selective solvent EA, DCE, MEK, and AC components, for the vinyl acetate (VA) segment in EVA copolymers, in the solvent mixtures. The solvent effect of ΔTPP occurring in wax solutions can also come from the solutions of EVA polymer, which were prepared by solvent mixtures with various compositions and used as parent solutions of EVA pour point depressant. From the experimental results such as the NMR of EVA macromolecules; viscosities of EVA, waxes, and their blends; and solubilities of wax with and without EVA macromolecules in the solvent mixtures, the complexation between wax molecules and ordered ethylene segment, and wax solubilization within ordered ethylene segments in EVA macromolecules are suggested for qualitative description of the observed significant variation of ΔTPP. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 815–821, 2002

Measurable difference in Cherenkov light between gamma and hadron induced EAS

We describe the possible measurable difference in the Cherenkov light component of EAS induced by an electromagnetic particle (i.e., e +, e − or γ) and induced by a hadron (i.e., proton or heavier nuclei) in the TeV range. The method can be applied in experiments which use wave front sampling method of EAS Cherenkov light detection (e.g., THEMISTOCLE, ASGAT).

Estimate of the chemical composition of cosmic rays from a multifractal moments analysis of the lateral particle distributions in the core of high-energy EAS

The central detector of the KASCADE experiment, which is focused to investigate the chemical composition of primary cosmic rays by EAS observations in the energy range of 1014 eV to 1017 eV, is able to observe the density distributions of the EAS components in the shower core, in particular of the muons by large-area position-sensitive multiwire proportional chambers (MWPC), installed below an iron sampling calorimeter (≈ 1000 g/cm2 Fe) used for hadron measurements. Using a method based on the determination of multifractal moments the appearance of the density distributions of the EAS core in the MWPC has been analyzed. Results with EAS simulations indicate distinct signatures for the mass of the primary. We communicate first results extracted from measurements with the MWPC combined with measurements of the energy deposit in the timing and trigger facility (segmented scintillation detector plane as third active layer of the calorimeter) of the KASCADE central detector.

Muon content of UHE air showers: discrimination method between electromagnetic and hadronic cascades

Results from a detailed Monte Carlo simulation for the muon component of EAS, at mountain altitude (800 g cm-2), generated by vertical gamma -rays, protons, oxygen and iron primary cosmic rays, in the energy range 1012-1016 eV, are provided for muon threshold energies from 0.1 to 100 GeV. In the simulation of the different components of the shower ( mu +or-, e+or-, gamma ...), the CORSIKA (cosmic ray simulator for cascade) code has been used to allow for both, electromagnetic and hadronic interactions. Results on the variation and fluctuation of the total muon number with shower size and primary energy are obtained, as well as longitudinal developments, lateral distributions of low-energy muons in air showers and muon energy spectra. Moreover, analytical expressions are fitted to the muon lateral developments, and muon energy spectra have been parametrized to a log-normal distribution. Apart from their value as new results, they may be used for the design of current studies at mountain altitudes. We also seek to provide relations to interpret the experimental data, for those who do not have detailed simulation calculations available.

Constant efficiency selection of EAS with energies 105-107 GeV at observation level 700 g cm-2

A new EAS selection method is developed and applied for analysis of Tien Shan experimental data. It is shown that it is possible to select, at an observation level of 700 g cm-2, showers with energies 105-107 GeV with constant efficiency, i.e. not depending on the nature of the initiating primary particle. The proposed method tested on the basis of muon and electron EAS components gives the basis for a practically unbiased estimation of the mass composition and energy spectrum of the primary cosmic radiation in the energy interval 105-107 GeV using EAS experimental data obtained at mountain altitudes.

UHE cosmic ray event reconstruction by the electromagnetic detector of EAS-TOP

Abstract UHE cosmic rays are studied by means of the detectors of the different components of secondaries produced by their interactions in the atmosphere (EAS). We describe and discuss the reconstruction techniques and accuracies of the e.m. detector of EAS-TOP. They allow, besides independent high resolution measurements of UHE γ-ray astronomy, good correlation possibilities with the detectors of the different EAS components.

Energy dependence of the mass composition of primary cosmic rays in the 1-10 PeV energy interval

The authors have analysed fluctuations of EAS muons and electrons, energy spectra of electromagnetic, muon and hadron EAS components and ratios between energies of these components. It is shown that the most likely explanation of the whole data set is that the primary mass composition grows heavier smoothly from low energies approximately GeV up to PeV energies and continues growing heavier in the 1-10 PeV range, which includes the 'knee' of the energy spectrum. A model with the constant, but heavier than normal, composition in the 1-10 PeV energy range does not contradict experimental data, although the fits is less satisfactory. Models in which the composition becomes lighter immediately above the 'knee' are in contradiction with the experimental data.

Further study of the muon content of γ-induced EAS at haverah park

This paper describes observations of the muon component of PeV EAS from the direction of Cygnus X-3 detected with the GREX array between 1st October 1988 and 30th September 1989. Although no time averaged excess is seen there is an indication of emission at phase 0.25–0.30 in the 4.8 hr period when higher energy showers, contianing more than the expected number of muons, are considered.

A system to record the time spread of muons in extensive air showers

A recording system designed to measure the time spread of the muon component of EAS is described. The detectors are three 10 m 2 shielded liquid scintillators separated by distances of 150 m and 250 m. The recording system incorporates high speed storage oscilloscopes in order to preserve the risetime of the scintillator response whilst the widely spaced EAS detector array produces a coincidence trigger pulse. Using nanosecond electronics the major contribution to the instrumental risetime is demonstrated to be related to the properties of the scintillator material. The system's response to local EAS is investigated.

The electromagnetic component of cosmic-ray extensive air showers

The electromagnetic component of EAS has been studied using unshielded scintillator detectors at Haverah Park. Data on the lateral distribution of the response are presented. A comparison of data from various arrays is undertaken and some disagreement is found. The predictions of model cascade calculations are also compared with the current experimental results. The problems of treating the low-energy components of the EAS are considered.

A MODEL FOR THE ION-PAIRS OF TRIS(TRIMETHYLENEDIAMINE)COBALT(III) WITH POLYOXYANIONS. THE ORIGINS OF THE CIRCULAR DICHROISM CHANGES

Abstract Through structural and circular dichroism spectral comparison, 1,1,1-tris(3′-aminopropylaminomethyl)-ethanecobalt(III), Co(spn)3+, has been determined to be a model for the oxyanion ion-pairs of Co(tn)3 3+. The CD spectral changes of δ-Co(spn)3+ in the presence of oxyanions in conjunction with previous investigations suggest that conformational changes of the six-membered rings cause the intensities of the Ea and A2 components of the octahedral T1 g band to change in a direction opposite to that observed when only asymmetric nitrogens are generated, either by oxyanion hydrogen bonding or by means of an alkyl cap. It appears that when both effects occur together it is the conformational change that dominates the CD spectral changes. In the absence of conformational change the asymmetric nitrogens cause the Ea component to decrease while the A2 component increases, as was found in previous studies. The nickel(II) and copper(II) complexes of spn are reported also.

The lateral distribution of muons in near vertical EAS

A large-area muon detector (12.5 m2) has been used to investigate the muon component of large EAS at Haverah Park of size 0.27< rho 500<2.5 for zenith angle ( theta )<25 degrees . The analysis is based on 821 showers covering core distances of 160 m to 500 m. The results are compared with other observations and with recent model calculations. It is found that only certain models are in reasonable agreement with the experimental data.

Calculations of average characteristics of EAS components and Monte Carlo calculations of their fluctuations using different models of nuclear interactions. II. Muons

The results pertaining to the muon component obtained in the calculations described in Part I are presented. The predicted lateral distributions and energy spectra of muons with energies above various thresholds are compared with experimental observations. Also presented are the expected variations of the number of muons with shower size compared with experimental results. None of the models assumed predict in every detail the results obtained experimentally. Modifications that could possibly be made are indicated.

Calculations of average characteristics of EAS components and Monte Carlo calculations of their fluctuations using different models of nuclear interactions. III. Nuclear-active particles

Results concerning NAPs from calculations described in Part I are given here. (1) Nucleon-pair-producing models give results in agreement with the observed size variation, integral energy spectrum, and delay distribution of NAPs. (2) Fluctuations in NAPs are partly correlated to fluctuations in the electron lateral structure parameter. (3) A nonlinear size variation of low-energy NAPs is expected from a changing primary composition model. (4) The usefulness of ultra-high-energy neutral events, the number of NAPs, and core structure studies in distinguishing between proton and heavy primaries is discussed.

Calculations of average characteristics of EAS components and Monte Carlo calculations of their fluctuations using different models of nuclear interactions. I. Methodology—Lateral structure and transition curve of electrons

Properties of extensive air showers are computed by two methods based on eight plausible models of ultra-high-energy interactions of nucleons and pions with air nuclei. The first method is the numerical solution of the diffusion equations describing the one-dimensional nuclear cascade, from which the average properties of nucleon-initiated showers of given energy are deduced. The second method is Monte Carlo simulation of the three-dimensional nuclear cascades from a sample of which typical shower properties and the extent of their fluctuations are estimated.1. For showers of size &lt; 106, the deduced shower absorption lengths are consistent with experimental results only for models involving nucleon pair production.2. The accuracy of experimental results on the depth of the shower maximum at different primary energies (105–1010 GeV) available at present is insufficient to select any particular model.3. Monte Carlo size distributions for a given primary energy indicate that with the primary energy spectrum known at present, showers of a given size originate from primaries of a relatively narrow range.4. The electron lateral structure parameter, α, fluctuates considerably for showers of primary energy &lt; 106 GeV; the spread decreases with the primary energy.5. The average value of α increases with primary energy up to 106 GeV and saturates at ~ 1.2 for showers of larger sizes.

Phenomenological characteristics of EAS at sea level: EAS size spectra and fluctuations of EAS

Experimental EAS spectra of sizes and muon numbers and results on the fluctuations of the electron–photon and muon EAS components at sea level are presented. In constructing size spectra the sizes of showers were determined by use of the individual lateral distribution function. Experimental data were obtained with considerably better statistics than in our previous works.

Optical rotatory power of co-ordination compounds. Part V. The outer-sphere complexes of the tris-diamine–cobalt(III) complex ions

The stability constants of the outer-sphere complexes MLn, n= 1–4, formed by the (+)-trisethylenediamine-cobalt(III) ion (M) with selenite (L) have been determined from circular-dichroism measurements in aqueous solution at constant ionic strength, and from the formation constants the circular-dichroism spectra of the individual complexes MLn have been obtained. From similar measurements and known stability constants, the circular-dichroism spectra of the outer-sphere complexes MLn have been derived for L = thiosulphate, n= 1–4, and L = ferrocyanide, n= 1 or 2. The results show that the rotational strengths of the A2 and the Ea components of the octahedral T1g transition of cobalt(III) are enhanced and diminished, respectively, in the complexes MLn with n odd, and that the circular-dichroism spectrum reverts towards that of the free complex ion M in the corresponding complex MLn+1. Trends in the relative stabilities of the outer-sphere complexes and in the intensity of the interionic charge-transfer absorption and circular-dichroism bands indicate that dispersion and charge-transfer forces become progressively more important in outer-sphere co-ordination as the overall charge of the complex MLn becomes more negative. In the group D3 of the free complex ion the charge-transfer transition has E symmetry in the complexes MLn with n odd and has components with A2 and E symmetry if n is even.