The alpha channeling effect

Author(s):  
N. J. Fisch
Author(s):  
K. Izui ◽  
S. Furuno ◽  
H. Otsu ◽  
T. Nishida ◽  
H. Maeta

Anisotropy of damage productions in crystals due to high energy electron bombardment are caused from two different origins. One is an anisotropic displacement threshold energy, and the other is an anisotropic distribution of electron flux near the atomic rows in crystals due to the electron channeling effect. By the n-beam dynamical calculations for germanium and molybdenum we have shown that electron flux at the atomic positions are from ∽4 to ∽7 times larger than the mean incident flux for the principal zone axis directions of incident 1 MeV electron beams, and concluded that such a locally increased electron flux results in an enhanced damage production. The present paper reports the experimental evidence for the enhanced damage production due to the locally increased electron flux and also the results of measurements of the displacement threshold energies for the <100>,<110> and <111> directions in molybdenum crystals by using a high voltage electron microscope.


2020 ◽  
Vol 17 (3) ◽  
pp. 301-311
Author(s):  
Claire C. Beauchesne ◽  
Morgan Chabanon ◽  
Benjamin Smaniotto ◽  
Benoît Ladoux ◽  
Benoît Goyeau ◽  
...  

2010 ◽  
Vol 17 (4) ◽  
pp. 042112 ◽  
Author(s):  
Abraham J. Fetterman ◽  
Nathaniel J. Fisch

1992 ◽  
Vol 279 ◽  
Author(s):  
M. Rahman ◽  
M. A. Foad ◽  
S. Hicks ◽  
M. C. Holland ◽  
C. D. W. Wilkinson

ABSTRACTDry etching can introduce defects into the material being etched. Simple expressions for both sidewall and top surface defect distributions may be obtained by assuming that the defects are introduced according to a phenomenological source function. Calculations of conductance based on these expressions are found to describe very well measurements on dry-etched wires and epilayers. Mechanisms by which defects can penetrate into the sample are discussed. The role of sample heating and defect diffusion is examined. In-situ measurements of sample temperature during a dry-etch run indicate that simple diffusion is insufficient to account entirely for the observed damage. Instead, dry-etch damage may arise from other mechanisms such as by knock-on replacement collisions, or via a channeling effect. A more complex form of diffusion may also affect the final damage distribution.


2017 ◽  
Vol 61 (13) ◽  
pp. 1703-1728 ◽  
Author(s):  
Dominique Clément

Channeling theory posits that external funding for social movements, rather than coopting activism, channels activism into more structured and less militants forms. Studies on channeling, however, focus on private funding. The following article examines whether public funding has a comparable effect on social movements. Using the human rights movement in Canada as a case study, it examines several issues relating to channeling: why funders support activism; funding as social control or altruism; how funding is related to consolidating movement gains; and the impact of funding on mobilization, activism, and internal movement dynamics. To address these questions, this article draws on an innovative new data set that includes lists of grants extracted from more than 30 years of government budgets in Canada. It also draws on several years of archival research on a network of 19 organizations in every region of Canada, as well as interviews with former members of these organizations. In addition to demonstrating that public funding has a comparable channeling effect as private funding, this article provides the first comprehensive survey of the extent of state funding for the human rights movement in Canada.


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