Distribution Of Secondary Particles Research Articles

Mu-Meson Component of Air Shower Below the Ground

Mu-meson component, observed underground, of the extensive air shower is studied, which has come from the nuclear cascade of the shower core in the ground and possibly shows high concentration of mu-mesons below the ground. The total number of them can be estimated independently of energy and multiplicity distributions of secondary particles of the elementary collision each of shower particles undergoes, and also independently of some fluctuations. It is only because they depend upon the whole feature of the nuclear cascade in the shower core. Experimental data of the multiple penetrating particles (M.P.P.), whose feature is the high concentration of mu-mesons, could not be interpreted in terms of those mu-mesons, i. e., decay products within the nuclear cascades in the ground initiated by impinging nucleons of high energy in the air shower cores, even though the possible contribution of the K-meson and Hyperon production in the high energy collisions within nuclear cascades is taken into consideration.

Angular Distributions of Secondary Particles Produced in High-Energy Nuclear Collisions and the Two-Center Model of Multiple Meson Production

The angular distributions of shower particles from 54 nuclear interactions of protons and neutrons with energies g ${10}^{12}$ ev in a stack of nuclear emulsions are analyzed. The method consists essentially in normalizing the angular distributions of all events in the $x=logtan\ensuremath{\theta}$ scale to the same dispersion $\ensuremath{\sigma}$. One finds a very significant deviation from the normal distribution predicted by hydrodynamical models. The deviation goes in the direction indicated by the two-center model (two maxima in the plot over the $x$ coordinate). The correlation between the separation of the two emitting centers and $\ensuremath{\sigma}$ is also in qualitative agreement with the model. The angular distribution in the rest system of the emitting centers is found to be roughly isotropic. The two-center model also offers an explanation for certain characteristic features observed for the angular distribution of events with a small number of shower particles (${n}_{s}\ensuremath{\leqq}5$). On the basis of this model a coefficient of inelasticity of \ensuremath{\approx}0.2 is obtained for these events.Interactions characterized by small evaporation (${N}_{h}\ensuremath{\leqq}5$) and small numbers of shower particles (${n}_{s}\ensuremath{\leqq}20$) show the characteristic two-maximum shape. The same shape is found for presumably central collisions with heavy nuclei in the emulsion (${N}_{h}g8, {n}_{s}g40$). However, the group of collisions with ${N}_{h}\ensuremath{\leqq}5$, ${n}_{s}g20$ does not show the two maxima. The last two observations cannot be explained by the present simple form of the two-center model.The results of this paper are in good agreement with a similar analysis carried out by Gierula, Mi\ifmmode \mbox{\k{e}}\else \k{e}\fi{}sowicz, and Zielinski.

On the Nuclear Interaction of Mu-Mesons

The penetrating showers observed with a large multiplate cloud chamber at 50 mwe and 250 mwe underground have been analyzed. The frequencies of the penetrating showers which are experimentally verified to be produced by mu-mesons have been interpreted with the Williams-Weiszacker method and the constant photonuclear cross section of 1.4×10 -28 cm 2 /nucleon. It has been also shown that the angular distribution of secondary penetrating particles in multiple productions produced by mu-mesons is nearly isotropic in the center-of-mass system of the target nucleon and photon which is virtually associated with the incoming mu-mesons.

The angular distribution of secondary particles in high energy nuclear collisions with heavy nuclei of photographic emulsion

61 jets produced by singly charged and neutral particles of cosmic radiation in photographic emulsion in collisions with heavy nuclei (Nh>8) have been investigated. Primary energies and anisotropy parameters for angular distributions of secondary particles have been calculated. The results were compared with those obtained formerly for events with mall evaporation (Nh⩽5). It might be stated that the energy dependence of the anisotropy for both samples of jets is quite similar. The mean anisotropy is however smaller than that predicted by hydrodynamical theories. It was stated that in the same energy interval the anisotropy for particular events differ very much and that the main contribution to high anisotropy is given by the cases in which the angular distribution dN/d(log tgθ) is not a normal one, but shows two separated maxima. The results were discussed from the point of vew of the two-centre model.

Double maximum angular distributions in high energy nuclear collisions

A detailed statistical analysis of the shape of the angular distribution of secondary particles generated in 65 nuclear collisions for primary energies higher than 1012 eV has been presented. The double maximum shape of the distribution (in coordinate log tgθ) is a general feature of the events with high degree of anisotropy of secondaries in CM system. It has been found that the shape of the angular distribution is in agreement with the predictions of the two-centre model of multiple meson production both for nucleon-nucleon and nucleon-heavy nucleus collision. A new parameterD, which is a measure of the deviation from the normal shape of the distribution towards the two centre distribution and also a coordinate convenient for visualizing this deviation, have been introduced.

Nuclear interactions in the energy region (1010 ÷ 1014) eV

Measurements of angular distributions of secondary particles in interactions of high energy primaries of cosmic radiation with the nuclei of photographic emulsion have been performed. A systematic increase in anisotropy of angular distribution in C.M. with increasing primary energy has been stated. It was found that in many high energy jets the number of secondaries in the vicinity ofπ/2 C.M. angle in smaller than that predicted by the theories of Heisenberg or Landau. For explaining these experimental results a model has been introduced in which the secondaries are emitted isotropically from two centres moving in opposite direction in the C.M. system. Some experimental arguments have been given for this isotropy. The relation between the velocity of two centres, the inelasticity coefficient, multiplicity and transversal momenta of secondaries has been discussed.

On some interaction characteristics of very high-energy particles and their interpretation from the view point of the hydrodymical yheory of multiple particles production

S>Landau, using the idea stated by Fermi, employed relativistic hydrodynamics in describing very high energy particle collision. The first attempts to compare the conclusions of hydrodynamical theory with experimental data on the multiplicity and angular and energy distributions of secondary particles already showed that the hydrodynamical theory satisfactorily described many multiple process characteristics. By comparison of the theory with experimental data taken from the analysis of showers recorded in photographic emulsion, a number of essential additional assurnptions were made. These assumptions caused a certain obscurity of the conclusions. For example, it was assumed that the collision of nucleons with heavy nuclei took place in the coordinate system in which notion of substance was symmetrical. Extensive shower analysis carried out on the assumption that the nuclear interaction cross section is independent of energy shows that the formal part of the hydrodynamical theory is incomplete. (A.C.)

Nuclear Interactions in Nucleon-Proton and Nucleon-Carbon Nucleus Collisions above 10 GeV

Nuclear interactions in hydrogen and carbon by nucleon (a few to several tens of GeV) have been studied using a multiplate cloud chamber which contained paraffin, carbon and lead at mountain altitude. The cross-section for the nuclear interaction by nucleon-proton collision was found to be 60±17 mb, assuming the cross-section for nucleon-carbon nucleus 320 mb. Energy spectra of neutral pions produced in paraffin, graphite and lead were compared. The energy distribution of neutral pions in paraffin-interactions is more steep in low energy region and similar in high energy region compared with that in carbon-interactions, and possible interpretation will be given. Charged secondary particles are emitted isotropically in c.m. system in nucleon-nucleon collision, and in the carbon nucleus some secondary particles undergo secondary collisions in the same nucleus. The azimuthal angle distribution of secondary particles was examined and some comments will be mentioned.

On the angular distribution of secondary particles of high energy jet showers

The data from nucleonic component detectors (neutron intensity monitors) are analyzed for the amplitude and phase of maximum intensity of the 24 hr variation at the geomagnetic equator and at 48 deg N. The same analysis is performed on selected charged particle detectors. The analysis covers 1953-55, which includes the time of solar cycle (sunspot) minimun in 1954. Puring 1954 it is known that the 24 hr variation possesses an anomalous behavior. It is shown that during 1953 there is an interval of 9 months or more when the solar daily variation appears to undergo a progressive phase shifi whose time of maximun lies in the range of 0800-1000 hr on a sidereal time scale. This anisotropy certainly exists in the radiation falling upon the atmosphere, and it is likely, although not proven, that the anisotropy prevails even outside the terrestrial field. The question of whether this sidereal effect is spurious or real is discussed in relationship to the recent results on the modulation of cosmic ray intensity within the solar system. (auth)

Analysis of Secondary Particles Resulting from High-Energy Nuclear Bombardment

Experimental studies have been made of the low-energy yields of secondary particles resulting from high-energy bombardment. For this purpose, thin foils of Be, Al, Ni, Ag, Au, and U have been bombarded by an internal beam of 375-Mev alphas, 332-Mev protons, and 187-Mev deuterons. Secondary particles emerging from the disintegration of the nucleus at 0\ifmmode^\circ\else\textdegree\fi{} to the incident beam direction are magnetically analyzed and detected in nuclear emulsions located beneath the median plane of the 184-inch cyclotron. There are three specific positions for these emulsions corresponding to energies of the secondary protons and of alpha particles of approximately 6, 10, and 20 Mev. This apparatus was modified to make a special study of the secondary alpha and proton yields by including two extra plates so that 10 energy points could be taken in the range from approximately 5 to 22 Mev. The angular distribution of secondary particles has also been measured for 240-Mev alpha bombardment of Be, Al, Ni, and Ag. Here, secondary particles emitted at 0\ifmmode^\circ\else\textdegree\fi{}, 45\ifmmode^\circ\else\textdegree\fi{}, and 135\ifmmode^\circ\else\textdegree\fi{} are detected in nuclear emulsions at positions for which the secondary proton and alpha energy is approximately 6 Mev. A secondary particle is identified by measurement of its radius of curvature upon entering the emulsion and its range and specific ionization in the emulsion. A considerable yield of hydrogen and helium isotopes as well as of particles of higher atomic number is found. The relative yields of the secondary protons and alpha particles for each element and for each bombardment are shown as a function of energy. The results, while found to be consistent with the predictions of an evaporation model, also indicate that a large percentage of secondary protons and alphas are directly knocked out of the nucleus.