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Primex Photon Beam Stability at HyCal

Primex Photon Beam Stability at HyCal. Waightstill W. Avery NC A&T July 11, 2008. Purpose. Determine the photon beam positions and resulting stability during the experimental run at HyCal using EPICS data. Definitions.

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Primex Photon Beam Stability at HyCal

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  1. Primex Photon Beam Stabilityat HyCal Waightstill W. Avery NC A&T July 11, 2008

  2. Purpose • Determine the photon beam positions and resulting stability during the experimental run at HyCal using EPICS data

  3. Definitions • BPM – Beam Position Monitor ( permanent hall-B BPM 2C24A ) • HyCal – Hybrid Shower Calorimeter • Pb Glass • PBWO4 crystals • PGP – Primex Gamma Profiler • All devices are assumed to be in the same frame of reference, with HyCal requiring an initial offset that was acquired from a survey • The angles ( x, y, z) are measured from their respective positive axes

  4. Process • Three databases were used for data extraction using MySQL protocols • ncat2.jlab.org/beamOrientation • primexdb.jlab.org/book_keeping • ncat3.jlab.org/test • 112 runs (used in Ilya’s0analysis), dubbed “Gold”, “Silver” and “Empty Target” runs, were used to extract EPICS datafrom these databases • For every EPICS event within individual runs the x and y-coordinates were retrieved for both the BPM and the PGP • Assuming that no magnetic field exists between the BPM and HyCal, parametric equations for a straight line trajectory were created to give the transverse coordinates on the face of HyCalrelative to the BPM and PGP

  5. Calculating Angles at HyCal • The law of cosines was used as a test to verify that our angle calculations were valid and returned a value of one for each EPICS event • Subtracting the angle from 90-degrees shows the deviation in each direction from the initial beam trajectory ’X/Y = /2 - X/Y

  6. Golden Beam Tune - Run 4349

  7. Removal of Beam-Trips

  8. Removalof Beam-Trips

  9. Summary • After the Golden Tune of the photon beam was established, beam-trips wereremoved usingJuLeia’s live time analysis • The beam position variations were well within HyCal resolution ( 1.3 mm) • The database was updated with the newly calculated x & y-coordinates of the beam at HyCal, as well as the x, y, and z angular deviations for each EPICS event for each run • The acquired information can be used to correct 0 trajectory • The updated data is available for collaboration-wide use

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