الفهرس 
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Abstract
This work is a study of an electromagnetic interaction of high energy muons with emulsion nuclei. This field of research is one of few ways to investigate the fissility of unstable nuclei. Besides; it is a good way to probe many physics aspects. The reaction mechanism in this study is described according to scenario in which the high energy muon particle is looked upon as a lump of intense electromagnetic field moving at a high speed. The target nuclei that are encountered by this field are excited by receiving a number of photons at a large range of the impact parameter so that it is considered an ”ultra-peripheral” interaction. Thus, the projectile and target particles do not penetrate through each other but instead, the target nucleus is excited by the absorption of virtual photon(s) in the electromagnetic field of the incident particles then decays by particle emission.
In this study, the target nuclei are the composition of nuclear emulsion pellicles of the type equivalent to BR-2 type (containing H, C, N, O, Ag and Br- nuclei with defined relative concentrations). These pellicles were irradiated with 160 GeV - beam of muons at CERN and processed at the ”Nuclotron Lab” of the Joint Institute for Nuclear Research (JINR, Dubna- Russia).
According to the sum of produced fragment charges, the major constituent elements were divided into two broad target groups; light (C, N, O) and heavy (Ag, Br). The data were collected by the area scanning technique of the nuclear emulsion plates of our study. Track counting and track parameter determination were performed using an optical microscope of model ”Olympus BH-2” using 100X oil emersion objectives and 15X eyepieces. The field area is calibrated using standard slits and a fine micrometer attached to eye piece lens of 0.1 μm per division.
A total of 820 interaction events of the muon projectile with emulsion target nuclei were collected by the research group workers. The emitted fragments from the target were observed as ionizing particles around the vertex of fragmentation. Thickness, coordinates and range, were measured carefully and recorded for each of the emitted fragments coming out of each event.
In order to study the mechanism of interaction through investing the parameters of the emitted particles from the excited targets we had to
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identify the charges of the outgoing fragments. This was made for each fragment by carefully measuring their relative widths.
The emission angles of the emitted fragments were measured. This was made by following up the x, y, and z coordinates of each fragment track, to determine their dip and projection angles and thus determine their space emission angles.
The energy of the fragments was determined by measuring the residual range of each particle and using special software for standard range–energy relation.
The analysis of above experimental results gave some fruitful facts that can be summarized in the following paragraphs:
# the emission of - particle fragments has shown a higher probability than that of other fragments in the interaction of the muon with the heavy target nuclei as well as with all the emulsion constituent nuclei ensuring that - particle is a tightly bound structure and that nuclei are mainly clusters of alphas.
# the angular distributions of the emitted fragments have shown isotropic behavior indicating one mechanism for emitting all of these fragments from the excited nuclei. This was also noticed in the emitted fragments of the residual excited nuclei in high energy hadrons and heavy ion strong interactions.
# fine angular studies of the emitted - particles have shown some strong short and long range correlations. The short range correlations indicated particle emitted from excited nuclei due to evaporation and splashing of cold vibrating nuclei, while the long range correlations suggested that the hydrodynamic collective flow was responsible for such correlation phenomena.
# the energy spectra of all types of the emitted fragments have shown different peak positions which would mean different ”boiling off” energies (temperatures) are specific for each emitted fragment from the nuclear matter.