Exchange Degeneracy and Oscillating Total Cross Sections

1971 ◽  
Vol 3 (11) ◽  
pp. 2861-2864 ◽  
Author(s):  
R. F. Amann
Keyword(s):  
Cross Sections ◽  
Exchange Degeneracy ◽  
Total Cross Sections

Proton-Proton Total Cross Sections and the Neglect of Masses in Data Fitting in the Regge Region

1981 ◽  
Vol 34 (2) ◽  
pp. 121 ◽  
Author(s):  
Mujahid Kamran
Keyword(s):  
Cross Sections ◽  
Data Fitting ◽  
Exchange Degeneracy ◽  
Interacting Particles ◽  
Proton Proton ◽  
Total Cross Sections ◽  
Regge Region ◽  
The Masses ◽  
Fitting In

It is shown by taking the example of pp total cross .sections that the use of the approximation s ~ 2qs-t while fitting data in the Regge region can be misleading. Several standard fits to O"tot(pp) data are based on the assumption of weak p-f-w-A2 exchange degeneracy (EXD). However, these fits involve the use of the approximation mentioned. We find, quite surprisingly, that it is impossible to fit the O"tot(pp) data in the range 6 ~ Plab ~ 2092 GeVjc using the precise factor 2qs~ in conjunction with weak p-f-w-A2 EXD. OUf investigation shows that O"tot(pp) data alone seem to indicate either a breaking of weak p-f-w-A 2 EXD or the presence of low-lying contributions, or both, provided one does not ignore the masses of the interacting particles in data fitting in the Regge region (Plab ;:;: 5 GeVjc). Caution is therefore urged in the use of such approximations in phenomenological calculations.

Analysis of STEM micrographs of thick objects

1978 ◽  
Vol 36 (2) ◽  
pp. 106-107
Author(s):  
S. Golladay
Keyword(s):  
Inelastic Scattering ◽  
Multiple Scattering ◽  
Mass Distribution ◽  
Cross Sections ◽  
Phase Contrast ◽  
Image Point ◽  
Contrast Effects ◽  
Total Cross Sections ◽  
Elastic And Inelastic Scattering

The theory of multiple scattering has been worked out by Groves and comparisons have been made between predicted and observed signals for thick specimens observed in a STEM under conditions where phase contrast effects are unimportant. Independent measurements of the collection efficiencies of the two STEM detectors, calculations of the ratio σe/σi = R, where σe, σi are the total cross sections for elastic and inelastic scattering respectively, and a model of the unknown mass distribution are needed for these comparisons. In this paper an extension of this work will be described which allows the determination of the required efficiencies, R, and the unknown mass distribution from the data without additional measurements or models. Essential to the analysis is the fact that in a STEM two or more signal measurements can be made simultaneously at each image point.

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