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The sign convention of element tilt #88

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z-duan opened this issue Nov 13, 2018 · 0 comments
Open

The sign convention of element tilt #88

z-duan opened this issue Nov 13, 2018 · 0 comments

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@z-duan
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z-duan commented Nov 13, 2018

Dear all,
When using "at/atmat/pubtools/LatticeTuningFunctions/errors/atsettiltdipole.m" to set the tilt error for elements, something seems inconsistent. In attiltelem.m, a straight element is tilted clockwise around the direction of beam motion by an angle PSI, while in atsettiltdipole.m, if following the same tilt sign convention for a dipole element, a "standard" bending magnet will be tilted clockwise, and leads to a horizontal kick that increase px, i.e., PolynomB(1) = -BendingAngle / Length * (1 - cos(PSI)) ; meanwhile, this also leads to a vertical kick that bends downward (decrease py), i.e., PolynomB(1) = -BendingAngle / Length * sin(PSI) . So I guess there is a sign error in the PolynomB(1) in atsettiltdipole.m.

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