Angular Distribution Of Shower Particles Research Articles

SOLAR SYSTEM OBJECTS AS COSMIC RAYS DETECTORS

In a recent Letter (Rimmer et al. 2014), Jupiter is presented as an efficient detector for Ultra-High Energy Cosmic Rays (UHECRs), through measurement by an Earth-orbiting satellite of gamma rays from UHECRs showers produced in Jupiter's atmosphere. We show that this result is incorrect, due to erroneous assumptions on the angular distribution of shower particles. We evaluated other Solar System objects as potential targets for UHECRs detection, and found that the proposed technique is either not viable or not competitive with traditional ground-based UHECRs detectors.

MULTIPARTICLE PRODUCTION IN SILICON-EMULSION INTERACTIONS AT 4.5 A GeV/c

We present and discuss results on multiplicity and angular distributions of shower particles produced in silicon-emulsion interactions at 4.5 A GeV/c. These results are compared with those obtained for different values of impact parameter. Shower width distribution has also been investigated.

Comparative study of various methods of primary energy estimation in nucleon-nucleon interactions

The various available methods for the estimation of primary energy in nucleon-nucleon interactions have been examined by using the experimental data on angular distributions of shower particles from p-N interactions at two accelerator energies, 67 and 400 GeV. Three different groups of shower particle multiplicities have been considered for interactions at both energies. It is found that the different methods give quite different estimates of primary energy. Moreover, each method is found to give different values of energy according to the choice of multiplicity groups. It is concluded that the E ch method is relatively the better method among all the methods available, and that within this method, the consideration of the group of small multiplicities gives a much better result. The method also yields plausible estimates of inelasticity in high energy nucleon-nucleon interactions.

Angular distribution of shower particles produced in the collisions of 30-400-GeV protons with emulsion nuclei.

For 3987 accelerator-produced jets of 30--400-GeV protons in nuclear emulsion, 's are individually calculated for each jet, where eta(theta) is a kinematic parameter introduced by us in 1967 in order to approximate the rapidity eta = arctanh(..beta.. costheta). Then by taking further averages by dividing the samples into groupings of the laboratory-system (LS) energy E/sub p/ of the primary proton ( = m/sub p/cosheta/sub p/), the number N/sub h/ of heavy prongs with LS velocity ..beta.. or approx. =0.7, the averages dlangleeta(theta)drangle are obtained. By use of the Koba-Nielsen-Olesen scaling variable xi = n/sub s//, we find good fits of the form dlangleeta(theta)drangle-eta/sub p//2 = A'+B'/xi, where A' and B' do not have any dependence on eta/sub p/ (i.e., on E/sub p/). The significance of our findings is discussed.

A study of inelastic pion-nucleus interactions at 200 GeV/ c in an emulsion

Results from a study of π-nucleus interactions in emulsion, at an incident momentum of 200 GeV/ c are presented and discussed. Some characteristics of heavy and shower-particle multiplicity distributions are reported and compared with the results from p-nucleus collisions at the same momentum. The angular distributions of shower particles are reported and analyzed in detail. It is shown, particularly, that one-particle distributions, being plotted in terms of pseudorapidity, have a bimodal structure in πA interactions. Also, pseudorapidity and azimuthal two-particle correlations are investigated. Considerable attention has been devoted to the exclusion of kinematical and trivial correlations. A qualitative comparison of the data with predictions of some model approaches has been performed.

Nuclear interactions of 300-GeV protons in emulsion

Results from a study of p-nucleus interactions in emulsion at an incident energy of 300 GeV are presented. The observed events were separated into those belonging to the light (C,N,O) and the heavy (Ag, Br) groups of target nuclei. Some characteristics of the fast-charged- (shower-) particle multiplicity and angular distributions for the light and heavy groups, as well as for emulsion, are reported and compared with the results from our previous experiments at 200 GeV. The average number of shower particles, , has the values /sub CNO/ = 12.1 +- 0.5, /sub AgBr/ = 16.7 +- 0.5, and /sub em/ = 15.1 +- 0.2. The quantity R/sub A/, defined as the ratio of created charged particles in p-nucleus and p-p collisions, is consistent with the relation R/sub A/ = A/sup 0//sup .//sup 19/. While the width of the shower-particle distribution as measured by the dispersion D is greater at 300 GeV than at 200 GeV, the value of /D is about 1.68 at both energies. The average number of slow charged particles resulting from the evaporation of the target nucleus remains virtually unchanged at the two energies. The angular distributions of shower particles plotted in terms of eta = -lnmore » tan(theta/2) show that, for a given nucleus, there are more particles at smaller angles at the higher energy, while there is no change in the distribution at large angles. In addition, for a given energy, the number of shower particles at larger angles increases with increasing size of the target nucleus.« less

The angular distributions of secondaries in proton-nucleus interactions at 200 and 300 GeV

The angular distributions of shower particles from proton-nucleus collisions at 200 and 300 GeV are investigated and correlated to the nuclear parameters (heavy prong emission), the inelasticity coefficient and the angle of the leading track. A partition is made into two components, the LP component associated with a single collision and the RC component corresponding to the excess from repeated collisions at the same proton and the nucleons inside the nucleus. Results from earlier investigations on the multiplicity distributions are confirmed. The LP component exhibits an excess of about 30% as compared to the shower particle emission in proton-proton collisions at the same energy. We find that the excess particles are slow moving in the equal velocity system, i.e., the frame in which the proton and the nucleus have equal but oppositely directed velocities. The opening angle of the cone inside which the proton-nucleus distributions are similar to the proton-proton distributions at the same energy is small (⪅ 0.5°) and is energy dependent. We also find indications of A dependence and a noticeable correlation to the inelasticity coefficient and to the angle of the leading track.

Observation of Nuclear Transparency in Proton-Nucleus Collisions at 200 GeV

Proton-nucleus interactions in nuclear emulsion from a 200-GeV proton beam at the National Accelerator Laboratory have been studied in terms of multiplicities and the angular distributions of shower particles. Low multiplicities observed in complex nuclei do not depend upon the size or the excitation of the target nuclei. Our experimental results are explained in terms of the energy-flux cascade model and not by intranuclear cascade models.

«Effective target mass» in proton-nucleon and pion-nucleon inelastic interactions at 16 and 28 GeV/c

Samples of 62 proton-nucleon and 121 pion-nucleon interactions in 28 GeV/c and 16 GeV/c pion beams respectively, were found in nuclear emulsions by following the along-the-track method. The effectivetarget-mass distribution for these events has been obtained from three independent methods. An empirical relation has been derived which could be used for finding the effective target mass from nucleon-nucleon and pion-nucleon interactions from the angular distribution of shower particles produced in these interactions. The distribution of7c (Lorentz factor in the center-of-mass system) is given with a marrow spread and is shown against an effective target mass of individual events. This distribution further supports the results of the above three methods. The inelasticity of these events is also diseussed in the laboratory as well as in the «mirror» system.

Azimuth angular distribution of shower particles in 24 and 27 GeV/cproton interactions in nuclear emulsions

Azimuth angles of shower particles produced in 24 and 27 GeV/c proton interactions have been analvsed by two methods (i) the method of consecutive angles, (ii) the `minimum fall-out' method It is concluded that azimuth angular distributions for stars with both NH 4 and NH 4 are consistent with isotropy and that spurious asymmetries can result from biased sampling

Inelastic interactions of pions and protons with complex nuclei at 5–30 GeV/c

A total of more than 2000 interactions in nuclear emulsion initiated by pions and protons of four different primary energies (between 5–30 GeV/ c) have been examined to study the general characteristics of stars produced in heavy nuclei. The analysis consists of the frequency as well as the angular distribution of shower particles, the correlation of 〈 n h〉 with n s and 〈 n s〉 with n h, the integral distribution of n h and the variation of lightly and heavily ionized tracks with the primary energy.

Relation between Angular Distribution of Shower Particles and Motion of Fire Ball

A dipole-type angular distribution of shower particles from multiple- meson-producing reactions is interpreted in terms of the finite angle of emission of a fire ball with isotropic emission of shower particles in the rest system of the fire ball. (R.E.U.)

Angular Distribution of Shower Particles from 1000-Bev Nucleon Alpha Particles on Emulsion Nuclei

Angular Distribution of Shower Particles from 1000-Bev Nucleon Alpha Particles on Emulsion Nuclei

High-energy interactions of a heavy primary in emulsion

Two successive high-energy interactions of a heavy primary cosmic ray particle in emulsion were analysed. The differential angular distribution of shower particles generated does not show any significant deviation from the distribution predicted by the hydrodynamical theory (4).

Nuclear Interactions and Mean Free Paths of Protons, Neutrons, and Alpha Particles at Energies Around 250 Bev/Nucleon

Nuclear interactions of protons, neutrons, $\ensuremath{\alpha}$ particles, and heavier nuclei of average energy 250 Bev/nuc were studied in nuclear emulsion. The source of these particles were fragmentations of heavy primary nuclei of the cosmic radiation. Their energy was determined from multiple scattering measurements. The interaction mean free path for protons is 41\ifmmode\pm\else\textpm\fi{}10 cm, for $\ensuremath{\alpha}$ particles 27\ifmmode\pm\else\textpm\fi{}7 cm. The mean free path shows no significant change compared with measurements at lower energies. The mean number of shower particles $〈{n}_{s}〉$ depends appreciably on the mass of the target nucleus. Our best estimate for nucleon-nucleon collisions at 250 Bev is $〈{n}_{s}〉=8.8\ifmmode\pm\else\textpm\fi{}1.9$. A detailed comparison of the estimate of the primary energy obtained from the angular distribution of shower particles with the true primary energy is carried out. The angular distribution of the shower particles will, in an individual case, give a quite unreliable value for the primary energy. In the average, the angular distribution method will over-estimate the true primary energy by a factor of 1.3 for interactions with a number of heavy prongs ${N}_{h}\ensuremath{\le}5$. If ${N}_{h}g5$, the angular distribution will underestimate the true energy in the average by a factor of 1.8. The angular distributions can be transformed into a system in which they are symmetric. This is even true for collisions with heavy target nuclei (${N}_{h}g5$). The results for alpha particle and heavy nucleus collisions are quite similar.The inelasticity for the proton and neutron interactions shows large fluctuations for individual events. It depends weakly on the number of shower particles and on the mass of the target nucleus. Its mean value is 50%. The mean value for the alpha-particle collisions is 22%.

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.

The analysis of 4.5 BeV negative pion interactions in nuclear emulsion

Abstract Two hundred nuclear interactions produced in Ilford G5 nuclear emulsion by 4.5 Bev π- mesons have been analysed. The transverse momentum of those secondary shower particles identified as pions has an average value over all angles of 290±50 MeV/C. The mean multiplicity of shower particles from the interactions is 2.0 ± 0.1 and is independent of the number of heavily ionizing prongs Nh . About 90 % of the shower particles were estimated to be pions. The angular distribution in the C-system is anisotropic with a mean value for |cos θ*verbar; of 048 ± 0.03. Assuming that secondary pions are emitted symmetrically backwards and forwards from a single collision system, the observed angular distribution of shower particles has been used to determine the effective mass of the collision partner. It is found to be 1.40+0.47 −0.27 proton mass units. If the total distribution is divided into groups with respect to Nh , it is found that events having Nh ≤7 yield a value of 0.77+0.36 −0.19 proton mass Units whi...

Evaluation of γ′0 from the angular distribution of jet particles in LS using certain suppositions about their angular distribution in the CMS

In this paper is made an attempt for finding the procedure for the evaluation ofγ′ 0 using for the integral angular distribution of shower particles in a jet three different suppositions. The derived expressions for the evaluation ofγ′ 0 in these three cases are proved on eight jets withγ′ 0 from 1 to 300.

On the angular distribution of shower particles generated in high-energy nuclear interactions

The differential and integral angular distributions of shower particles produced in high-energy nuclear interactions are calculated according to the multiple meson production theories of Fermi, Landau and Heisenberg8–11) for nucleon-nucleon interaction. Angular distributions calculated according to the theory of Landau are given for nucleon-nucleus interaction too. It is shown by summarizing the experimental data of jets of energies higher than 1013 eV that the angular distribution alone does not show unambiguously which of the multiple meson production theories, if any, is the correct one.

Multiple meson production and angular distribution of shower particles produced in cosmic ray « Jets »

In nuclear emulsions exposed to the cosmic radiation, showers have been studied (*) which are produced by singly charged or neutral particles, mainly perhaps nucleons (i.e. « Jets » or mesonic showers; their total, number being 22.) The analysis has been restricted to events whose primary energies are greater than 20 GeV, and the number of visible shower particles of which are equal to or greater than 8. An upper limit ofNh=3 for the « heavy » and « grey » prongs has been chosen for each event. (The total number of charged shower particles is 255 and of « grey » or « heavy » prongs is 28.) Such selected showers are interpreted in terms of multiple meson production, and the shower particles are supposed to be mainly mesons produced at one single nucleon-nucleon collision. Within the spread of primary energies observed (20 ÷ 500 GeV) the angular distribution of shower particles shows a significant deviation from isotropic emission in the centre of mass system of the two colliding nucleons.