Nuclear Events at High Energies

1954 ◽  
Vol 94 (6) ◽  
pp. 1724-1727 ◽  
Author(s):  
Joseph V. Lepore ◽  
Richard N. Stuart
Keyword(s):  
1953 ◽  
Author(s):  
J.V. Lepore ◽  
R.N. Stuart
Keyword(s):  

Author(s):  
L. M. Lewis

The effects of colchicine on extranuclear microtubules associated with the macronucleus of Paramecium bursaria were studied to determine the possible role that these microtubules play in controlling the shape of the macronucleus. In the course of this study, the ultrastructure of the nuclear events of binary fission in control cells was also studied.During interphase in control cells, the micronucleus contains randomly distributed clumps of condensed chromatin and microtubular fragments. Throughout mitosis the nuclear envelope remains intact. During micronuclear prophase, cup-shaped microfilamentous structures appear that are filled with condensing chromatin. Microtubules are also present and are parallel to the division axis.


Author(s):  
A. Howie ◽  
D.W. McComb

The bulk loss function Im(-l/ε (ω)), a well established tool for the interpretation of valence loss spectra, is being progressively adapted to the wide variety of inhomogeneous samples of interest to the electron microscopist. Proportionality between n, the local valence electron density, and ε-1 (Sellmeyer's equation) has sometimes been assumed but may not be valid even in homogeneous samples. Figs. 1 and 2 show the experimentally measured bulk loss functions for three pure silicates of different specific gravity ρ - quartz (ρ = 2.66), coesite (ρ = 2.93) and a zeolite (ρ = 1.79). Clearly, despite the substantial differences in density, the shift of the prominent loss peak is very small and far less than that predicted by scaling e for quartz with Sellmeyer's equation or even the somewhat smaller shift given by the Clausius-Mossotti (CM) relation which assumes proportionality between n (or ρ in this case) and (ε - 1)/(ε + 2). Both theories overestimate the rise in the peak height for coesite and underestimate the increase at high energies.


2001 ◽  
Vol 16 (1-2) ◽  
pp. 49-85
Author(s):  
A. De Roeck

1970 ◽  
Vol 101 (7) ◽  
pp. 385-428 ◽  
Author(s):  
Igor M. Dremin ◽  
Il'ya I. Roizen ◽  
Dmitrii S. Chernavskii

1976 ◽  
Vol 119 (7) ◽  
pp. 578
Author(s):  
Igor M. Dremin ◽  
G.B. Zhdanov ◽  
V.Ya. Fainberg

Author(s):  
Richard Wigmans

The energy resolution, i.e. the precision with which the energy of a showering particle can be measured, is one of the most important characteristics of a calorimeter. This resolution is determined by fluctuations in the absorption and signal formation processes. In this chapter, the different types of fluctuations that may play a role are examined, and their relative practical importance is addressed. Sources of fluctuations include fluctuations in the number of signal quanta, sampling fluctuations, fluctuations in shower leakage, as well as a variety of instrumental effects. Since the energy dependence of the different types of fluctuations is not the same, different types of fluctuations may dominate the energy resolution at low and and at high energies. An important type of fluctuations is part of the non-compensation phenomena. It concerns fluctuations in the strength of the electromagnetic component of hadronic showers. The effects of these fluctuations, which typically dominate the energy resolution for hadron and jet detection, are examined in detail. In sampling calorimeters, one particular shower particle may sometimes have catastrophic effects on the calorimeter performance. Several examples of such cases are discussed.


2012 ◽  
Vol 349 ◽  
pp. 011001
Author(s):  
Giorgio Giardina ◽  
Fabio Bossi ◽  
Paolo Levi Sandri ◽  
Paolo Pedroni ◽  
Hartmut Schmieden

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