Status Report: Emittance and IP Sizes from Synchrotron Light Alan Fisher

Procedure Measure beam size at the 3 source points: LER synchrotron-light monitor (SLM, visible light) HER SLM LER SXM (x-ray pinhole camera) Use the beam model to find emittances and IP sizes Model is put into database (Mark Woodley, Greg White) Model values at source points and IP are exported to EPICS (Mike Zelazny) Calculation includes coupling Schemes from Uli and from Yunhai Use measured sizes to solve for emittances at source point Use emittances to find IP sizes

Uli: Wolski’s Parametrization Wolski writes (LBNL-54774): n 11 2 =ß x, n 33 2 =ß y, n 12 =n 34 =0 the other n ij terms are written to the database, into the “WAKE” slots (-> M. Woodley)

Yunhai: Definition of Coupling Parameters Given one-turn matrix M, we can decouple it with a symplectic transformation: where u 1 and u 2 can be parameterized as if no coupling case and w is a symplectic matrix: There are ten independent parameters. Bar notes symplectic conjugate. g 2 =1-det(w).

Covariant Matrix and Eigen Emittances Given coupled lattice parameters and eigen emittance, we can calculate the  -Matrix: where  1 and  2 are defined as the case of no coupling: This formula is derived based on the fact that eigen emittances are Invariance around the ring.

Covariant Matrix and Beam Profile for a Gaussian Beam Useful matrix elements at any given point in the ring: Tiled beam distribution:  1 and  2 are eigen emittances and they are invariance like tunes in the ring. For a typical electron ring  1 >>  2.  is tilt angle, a and b are the lengths of major and minor axis respectively.

New Labview Window for MCC

Yesterday’s Model Work Model values in EPICS were incorrect SCP database could not update them Yesterday Woodley, White and Zelazny found a bug Loading a model into SCP database stopped before loading most values. No error message. Problem corrected. Updated models moved to EPICS. But the models gave a negative  y for both rings.

Compare to Yunhai’s Model This morning, Yunhai gave me his parameters for the HER source point and IP to compare: sensible results Start with HER SLM sizes = 1.3 and 0.19 mm Get emittances = 113 and 1.5 nm Get IP sizes = 218 and 6.2  m His off-diagonal terms of the 2  2 matrix equation for emittance are very different. Must find what’s wrong with the values from the on-line model.