scholarly journals Strange-quark vector currents and parity-violating electron scattering from the nucleon and from nuclei

1989 ◽  
Vol 39 (11) ◽  
pp. 3248-3256 ◽  
Author(s):  
D. H. Beck
Keyword(s):  
Electron Scattering ◽  
Strange Quark

scholarly journals THE NUCLEON'S MIRROR IMAGE: REVEALING THE STRANGE AND UNEXPECTED

2003 ◽  
Vol 18 (02n06) ◽  
pp. 75-84 ◽  
Author(s):  
R. D. MCKEOWN
Keyword(s):  
Form Factor ◽  
Electron Scattering ◽  
Strange Quark ◽  
Form Factors ◽  
Mirror Image ◽  
Vector Form ◽  
Electromagnetic Structure ◽  
Extensive Program ◽  
Axial Form ◽  
Insight Into

An extensive program of parity-violating electron scattering experiments is providing new insight into the structure of the nucleon. Measurement of the vector form factors enables a definitive study of potential strange quark-antiquark contributions to the nucleon's electromagnetic structure, including the magnetic moment and charge distribution. Recent experimental results have already indicated that effects of strangeness are much smaller than theoretically expected. In addition, the neutral axial form factor appears to display substantial corrections as one might expect from an anapole effect.

POLARIZED PARITY VIOLATING ELECTRON SCATTERING ON 3H AND ITS RELATION TO THE 3He CASE

2000 ◽  
Vol 09 (01) ◽  
pp. 1-16
Author(s):  
S. L. MINTZ ◽  
G. M. GERSTNER ◽  
M. A. BARNETT ◽  
M. POURKAVIANI
Keyword(s):  
Electron Scattering ◽  
Strange Quark ◽  
Form Factors ◽  
High Sensitivity ◽  
Figures Of Merit ◽  
Weak Minimum ◽  
Sharp Variation ◽  
The Asymmetry ◽  
The Difference ◽  
Asymmetry Parameters

We calculate the asymmetry parameters, A, and figures-of-merit for polarized parity violating electron scattering from 3 H via the reaction, e- + 3 H → 3 H + e- for incident electron energies of 1.0 GeV, 2.0 GeV, and 4.0 GeV. We find a sharp variation in A due to cancellations between the weak and electromagnetic form factors caused by the different q2 dependences of these form factors. These variations are similar to those found in the asymmetry for the reaction, e- + 3 He → e- + 3 He but occur at different angles due to the difference in form factors for the two cases. We find that at small angles, the asymmetry may be obtained to reasonably high accuracy for all energies considered and that there is a weak minimum in it at small angles for all of the energies considered here. We show that it might be possible to observe strange quark contributions to the asymmetry at this minimum due to the high sensitivity of A to strange quark contributions in this region. In addition we find that the asymmetry and figures of merit are in the range of those for other proposed target nuclei.

scholarly journals NUCLEON STRUCTURE AND PARITY-VIOLATING ELECTRON SCATTERING

2001 ◽  
Vol 10 (01) ◽  
pp. 1-41 ◽  
Author(s):  
DOUGLAS H. BECK ◽  
BARRY R. HOLSTEIN
Keyword(s):  
Electron Scattering ◽  
Strange Quark ◽  
Axial Vector ◽  
Nucleon Structure ◽  
Elastic Electron ◽  
Elastic Electron Scattering

We review the area of strange quark contributions to nucleon structure. In particular, we focus on current models of strange quark vector currents in the nucleon and the associated parity-violating elastic electron scattering experiments from which vector and axial-vector currents are extracted.

ASYMMETRIES IN POLARIZED ELECTRON SCATTERING AND THE STRANGENESS CONTENT OF THE NUCLEON

2009 ◽  
Vol 24 (11n13) ◽  
pp. 881-886
Author(s):  
SEBASTIAN BAUNACK
Keyword(s):  
Electron Scattering ◽  
Strange Quark ◽  
Form Factors ◽  
Strange Quarks ◽  
Quark Contribution ◽  
Nucleon Form Factors ◽  
Strangeness Content ◽  
Existing Data

In the viewpoint of QCD, the nucleon is made up of constituent quarks, sea quarks and gluons. Concerning the quark sea, also strange quarks can contribute to the nucleon properties. Parity violating electron scattering offers a tool to investigate the strange quark contribution to the nucleon form factors. The measurements of different experiments are discussed and the recent results from the A4 collaboration at MAMI is presented. Altogether the existing data allow to give constraints on the strangeness contribution.

Study of charge transfer in FeTi

1983 ◽  
Vol 41 ◽  
pp. 296-297
Author(s):  
J. Taft∅
Keyword(s):  
Charge Transfer ◽  
Charge Distribution ◽  
Electron Scattering ◽  
Periodic System ◽  
Electron Distribution ◽  
Scattering Amplitude ◽  
Transition Elements ◽  
Hartree Fock ◽  
Cscl Structure ◽  
The Right

It is well known that for reflections corresponding to large interplanar spacings (i.e., sin θ/λ small), the electron scattering amplitude, f, is sensitive to the ionicity and to the charge distribution around the atoms. We have used this in order to obtain information about the charge distribution in FeTi, which is a candidate for storage of hydrogen. Our goal is to study the changes in electron distribution in the presence of hydrogen, and also the ionicity of hydrogen in metals, but so far our study has been limited to pure FeTi. FeTi has the CsCl structure and thus Fe and Ti scatter with a phase difference of π into the 100-ref lections. Because Fe (Z = 26) is higher in the periodic system than Ti (Z = 22), an immediate “guess” would be that Fe has a larger scattering amplitude than Ti. However, relativistic Hartree-Fock calculations show that the opposite is the case for the 100-reflection. An explanation for this may be sought in the stronger localization of the d-electrons of the first row transition elements when moving to the right in the periodic table. The tabulated difference between fTi (100) and ffe (100) is small, however, and based on the values of the scattering amplitude for isolated atoms, the kinematical intensity of the 100-reflection is only 5.10-4 of the intensity of the 200-reflection.

Lithography below 100 nm

1983 ◽  
Vol 41 ◽  
pp. 96-99
Author(s):  
L. D. Jackel
Keyword(s):  
Spatial Distribution ◽  
Electron Beam ◽  
Electron Scattering ◽  
Electron Beam Lithography ◽  
Substrate Material ◽  
Local Electron ◽  
Electron Dose ◽  
Positive Resist ◽  
Exposure Process

Most production electron beam lithography systems can pattern minimum features a few tenths of a micron across. Linewidth in these systems is usually limited by the quality of the exposing beam and by electron scattering in the resist and substrate. By using a smaller spot along with exposure techniques that minimize scattering and its effects, laboratory e-beam lithography systems can now make features hundredths of a micron wide on standard substrate material. This talk will outline sane of these high- resolution e-beam lithography techniques.We first consider parameters of the exposure process that limit resolution in organic resists. For concreteness suppose that we have a “positive” resist in which exposing electrons break bonds in the resist molecules thus increasing the exposed resist's solubility in a developer. Ihe attainable resolution is obviously limited by the overall width of the exposing beam, but the spatial distribution of the beam intensity, the beam “profile” , also contributes to the resolution. Depending on the local electron dose, more or less resist bonds are broken resulting in slower or faster dissolution in the developer.

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