Particles In Extensive Air Showers Research Articles

Relativistic and non-relativistic dust grains

Charged dust grains of radiia≃3×10−6∼3×10−5 cm could be a help in understanding high energy particles in extensive air showers (EAS). It is suggested that the dust grains in the intergalactic medium may attain relatistic energy (≥1020 eV), and may be responsible for the apparent ‘bump’ in the energy spectrum. The relativistic and non-relativistic dust grains may help to understand the anomalies in the energy spectrum as regards the slope and intensity.

Suprathermal Grains: Origin of primary cosmic rays

Charged dust grains of radiia≃3×10−6 cm could be a help in understanding the production of primary cosmic ray particles in extensive air showers (EAS). A two-stage acceleration mechanism is proposed in order to accelerate dust grains up to relativistic energy. In the first stage, dust grains acquire suprathermal energy (‘Suprathermal Grains’) by the Fermi mechanism. In the second stage, suprathermal grains attain relativistic energy by the Alfven magnetic pumping mechanism yielding the primary cosmic ray particles. Ionization loss has been considered to be a most important loss mechanism for charged dust grains in a fully ionized medium. It is suggested that graphite dust grains of intergalactic origin may be responsible for high energy (>1020 eV) cosmic rays.

Search for heavy mass particles in extensive air showers

A large multiplate cloud chamber with fast timing scintillators inside is being operated with the extensive air shower array at Ootacamund to further elucidate the time structure of high energy hardons in air showers. The major interest in the present investigation is to understand the nature of the large delay (>20 ns) high energy (>40 GeV) events that appeared as strong cndidates for heavy mass particles in an earlier experiment carried out with a total absorption spectrometer. Two events observed during one year’s operation of the experiment are discussed.

A Study of Nuclear Active Particles in Extensive Air Shower

The high energy nuclear active particles (NAP) of more then 200 GeV, associated with EAS, have been studied by means of the large area scintillation detectors under water tank, at the mountain altitude of 2770 m a.s.l. We have obtained the following results; (1) The energy spectrum of NAP has a knee at about 500 GeV where the spectrum index changes from -1.0 to -1.8, (2) The lateral distribution of NAP can be expressed as A exp (- r / r 0 ) with r 0 of 1∼2 m, (3) The number of NAP is much smaller than the results of the Monte Calro simulations assuming the ordinary interaction model, and (4) The mean transverse momentum of NAP is about 2 GeV/c which is much higher than generally accepted value in the nuclear interactions.

On delays of particles in extensive air showers

Some features of the temporal distribution of the electrons in extensive air showers by means of the diffusion equations (Landau equations) in theA approximation are considered. The results are compared with data from experiments and Monte Carlo calculations.

High-energy N particles in extensive air showers at 800 g/cm2

The results on high-energy N particles in EAS using a total absorption spectrometer for energy measurement are presented. They are compared with results from other experiments and calculations based upon plausible models of high energy interactions. (1) As expected, the NAP lateral distribution becomes steeper for particles of higher threshold energies. (2) Contrary to expectation, the lateral distribution becomes flatter with increasing shower size. The implication of this anomalous behavior in terms of interaction characteristics at energies > 1014 eV is briefly discussed. (3) For a given size, showers with steeper electron lateral distribution have more NAPs. (4) Except for the behavior of the lateral distribution as a function of size, all the other results can be explained in terms of models in which pT and inelasticity distributions are invariant and some fraction (~15%) of nucleon–antinucleon pair production is assumed.

Energy Flow of Extensive Air Showers

Two sets of detectors of nuclear active particles have been cooperated in the extensive air shower arrays at sea level. The results obtained from these detectors agreed with each other, so that the energy spectrum of nuclear active particles in extensive air showers was determined with reasonable accuracy in the size range of 3.10 4 to 5.10 6 particles. At sea level the average energy of the most energetic nuclear active particles and the energy flow carried by nuclear active particles ( E >10 GeV) are nearly proportional to the shower size, and they are 1.2±0.4·10 12 eV and 5.3±2.0·10 12 eV respectively for the shower of the size (that determined from the scintillators) of 10 5 particles. These results and the energy carried by the electron photon component were compared with the calculated ones based on some conventional models of the nuclear interaction. The inelasticity and the mean free path of the nuclear interaction were thus obtained to be 0.65±0.15 and 80±10 gcm -2 respectively in the energy rang...

Density Spectrum of Charged Particles in Extensive Air Showers

A density spectrum of extensive air showers was obtained by means of a plastic scintillator at a mountain altitude, 2770 m above sea level. In the range from 50 to 10 4 particles/m 2 , the integral density spectrum is expressed as Δ -1.55±0.05 . By an EAS array the accompanied EAS's were also observed, and their contributions to the density spectrum were analyzed. The results are as follows. There is no agreement beween the exponent of density spectrum and that of size spectrum which was obtained directly from EAS array data in this experiment. This is due to the fact that the size of EAS is the larger, the lateral structure of the central region becomes steeper. Moreover, the lateral structure fluctuates considerably in the same size showers. The exponent of the density spectrum seems to decrease gradually with increasing altitude, the value on the mountain is 10% smaller than that of the sea level. Though statistical error is large, the exponent of the integral density spectrum increases from 1.55 to 2....

A Study on High-Energy Nuclear-Active Particles in Extensive Air Showers

A new type of detector called transition chamber was used to study high-energy nuclear-active particles ( N -particles) above 10 11 ev in extensive air showers (EAS) of size above 10 3 . The differential energy spectrum of N -particles is shown to be represented by E N -2.0±0.1 d E N up to 3.10 13 ev irrespective of shower size. The lateral distribution of nuclear-active particles is obtained within 10 m from the axis. This distribution is tentatively explained by a phenomenological model assuming the Maxwell-Boltzmann distribution for the transverse momentum of N -particles. Total number of N -particles of energy E N ≧10 11 ev, N N , in an extensive air shower is expressed as a function of size N e by N N =(50±5)( N e /10 5 ) 1.1±0.1 , for N e ranging from 10 3 to more than 10 6 . Then the total energy carried by all N -particles of E N ≧10 11 ev is estimated to be as much as that of the electron component in an EAS. On the basis of the observed general relationship between the electron component and N -particles for a wide range of sizes, a model of the development of EAS is suggested. The energy spectrum of N -particles is discussed in relation to that of high-energy γ-rays. In particular the existence of very high-energy N -particles implies that the average inelasticity in high energy interactions η=0.4∼0.5, if they assumed to be survivors of primary particles. Also the possibilities are discussed for the occurrence of N -particles with energies as much as 10% or more of primary particles.

Size-spectrum of extensive air showers of the cosmic radiation

Previously determined experimental and theoretical expressions for the lateral distribution of particles in extensive air showers are used to predict the response of a single scintillator to these showers. The integral rate of particles traversing the scirtillator is found in terms of the integral rate of showers; the average size of shower resulting in a given number of particles through the scintillator is calculated the effect of the zenith-angle distribution of the shower axes is investigated. (auth)

Size-spectrum of extensive air showers of the cosmic radiation

Previously determined experimental and theoretical expressions for the lateral distribution of particles in extensive air showers are used to predict the response of a single scintillator to these showers. The integral rate of particles traversing the scintillator is found in terms of the integral rate of showers; the average size of shower resulting in a given number of particles through the scintillator is calculated; the effect of the zenith-angle distribution of the shower axes is also investigated.

Directional Measurements on Extensive Air Showers

A search has been made for localized sources of high energy cosmic rays, by measuring the directions of arrival of the particles in extensive air showers with cloud chambers run in coincidence with a counter detecting system. An angular resolution rather better than 5° was achieved. No sources have been found between latitudes 10°N and 90°N on the celestial sphere for showers of average energy 8 × 1015 eV.

The Residual Range of Delayed Particles in Extensive Air Showers

The arrival times of the penetrating particles of extensive air showers relative to that of the electrons have been studied by means of short reaction time Geiger counters. A 50 channel hodoscope has been used to identify the penetrating particles and measure their residual ranges where these lay between 15 and 30 cm of lead. From observations on 782 showers of median density 70 particles m-' in which a Penetrating component was detected, it was deduced that between 3 and 9 particles in 104 shower particles from showers of median density 28 particles m-', have delays <5 X 10-8 sec and are able to penetrate 15 em of lead. It follows that 81-94 per cent. of the delayed particles found by Jelley and Whitehouse (1953) without the use of absorbers, must be stopped by 15 cm of lead. This indicates a height of production below 0�8 km for at least half of these particles.

Distribution of Arrival Times of Air Shower Particles

We have studied the instantaneous distribution of particles in extensive air showers at sea level by measuring the relative delays between particles with three liquid scintillation counters. The delays measured were in the range from 5 to 300 m\ensuremath{\mu}sec. The sizes of the showers were in the range from ${10}^{5}$ to ${10}^{6}$ particles. Using statistical methods of analysis we have found that at a given instant most electrons with energies of \ensuremath{\sim}20 Mev lie in a flat disk of thickness between 1 and 2 meters. The particles which can penetrate at least 20 cm of lead lie in a disk of thickness between 2 and 3 meters. The disk of penetrating particles follows behind the disk of electrons by less then 3 meters.We measured the projected zenith angles of the axes of individual showers by measuring the delays between widely spaced counters. The standard deviation of a measurement of the sine of the projected zenith angle of a shower was 0.13. The root mean square of the sines of the projected zenith angles was found to be 0.24\ifmmode\pm\else\textpm\fi{}0.015. If we assume a ${cos}^{n}\ensuremath{\theta}$ distribution law for the projected zenith angles we find $n=15\ifmmode\pm\else\textpm\fi{}1.2$. We determined the spatial orientations of the axes of individual showers by measuring the projections of the zenith angles on two mutually perpendicular planes.

The Time Distribution of Delayed Particles in Extensive Air Showers using a Liquid Scintillation Counter of Large Area

A liquid scintillation counter, of area 1000 cm2 and depth 15 cm has been developed for experiments on the delayed particles in extensive air showers. The scintillator was used in conjunction with two trays of Geiger counters to select showers of average density 10/m2; the prompt and delayed particles traversing the scintillator were recorded photographically in an arrangement in which possible sources of spurious delays were eliminated. The existence of delayed particles has been confirmed and the delay distribution obtained over the range (3-70) × 10-8 second. This distribution could be represented by an exponential function with half of the delayed particles arriving within (10 ± 2) × 10-8 second. The total fraction of shower particles that suffer delays in the above range was found to be (0.85 ± 0.05)%. There is evidence that showers with delayed events do not differ in average density from those without such events. A control experiment was carried out to investigate any spurious effects; this revealed μ-e decay events in the scintillator at approximately the expected rate.

Penetrating Particles in Extensive Air Showers

Extensive penetrating showers observed under a transition layer of lead 10 cm thick are approximately 300 times more frequent at 30 000 ft. than at sea level. A tentative analysis of their altitude variation suggests that the mean attenuation length in air of the N-component of extensive showers is of the order of 200 g/cm2. It is shown that in extensive showers at 30 000 ft. the fraction of particles which are penetrating is of the same order as at sea level.

Penetrating Particles in Air Showers

The penetrating particles in extensive air showers are compared directly with the penetrating particles in the main cosmic-ray beam. It is found that not more than 70±3% of the air-shower particles are single μ-mesons, whilst the remainder are strongly interacting particles. The barometer coefficient of extensive penetrating showers is determined.

Delayed Particles in Extensive Air Showers

AN attempt has been made, using two different experimental arrangements, to detect delayed particles in extensive air showers. In the first experiment (carried out under a thick concrete roof at University College, Dublin) extensive showers were selected by coincidences of three trays of Geiger-Muler counters, each tray of area 750 cm.2. The trays were placed at the apices of a triangle of sides 5.3, 7.3 and 8.5 metres. Pulses from a fourth tray of area 360 cm.2 occurring 1.4–11.4µsec. later were recorded.

A Cloud-Chamber Study of Extensive Air Showers at 3260 Meters Elevation

The penetrating particles in extensive air showers have been observed in a cloud chamber under 6 inches of lead at an elevation of 3260 meters. If a group of air showers is selected in such a way that their cores mostly land between 4 and 24 meters from the chamber, the penetrating particles are seen to consist mainly of $\ensuremath{\mu}$-mesons which have been produced in the air above the apparatus. If a group of air showers is selected so that their cores are mostly 6 meters from the chamber there are again many $\ensuremath{\mu}$-mesons and in addition there is evidence for local production of penetrating particles in mixed showers and high energy nuclear disintegrations produced by both neutral and ionizing penetrating particles. Thus we have evidence that high energy neutral particles and highly interacting ionizing particles make up an appreciable portion of the penetrating particles in the cores of air showers. There are more cascades of energy >${10}^{8}$ ev under the lead shield than can be accounted for by the radiation and knock-on processes of the observed number of mesons.

Momentum Spectrum of the Particles in Extensive Air Showers

An account is given of experiments on the momentum spectrum of the particles in extensive air showers at sea-level. The results are consistent with an integral spectrum of the form N(>E) α (E+Ec)-(1.1±0.3), where Ec is the critical energy in air. Penetrating particles are found in some of the denser showers, the ratio of penetrating particles to electrons being (0.8±0.4)%.