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IK/JJ May 6 th 2012

Results from EMMA Injection Line BPM-02 measurements on 25-04-12 May 6 th 2012 Ian Kirkman, James Jones. IK/JJ May 6 th 2012. Slide 0. Measurements. Data taken quickly at end of the final shift of the April 2012 commissioning run (25 th / 26 th )

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IK/JJ May 6 th 2012

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  1. Results from EMMA Injection Line BPM-02 measurements on 25-04-12 May 6th 2012 Ian Kirkman, James Jones IK/JJ May 6th 2012 Slide 0

  2. Measurements Data taken quickly at end of the final shift of the April 2012 commissioning run (25th / 26th) Initial aims: to demonstrate that the summed value of the 4 pickup voltages from a cylindrical BPM varies linearly with bunch charge; to examine beam position vs bunch charge. Method: • ALICE in SB mode at 5 Hz • Switch off DIP-02, monitoring charge in Faraday cup DUMP-01 • Set ALICE attenuation level (proportional to laser power?) • View FC response on ‘scope, and save digitised data to file • Issue multiple EPICS ‘caget’ commands at each attenuation level to read BPM-02, and save data to file IK/JJ May 6th 2012 Slide 1

  3. Measurements Oscilloscope screens for attenuation level at the 2 extreme values, 1.0 (left) and 0.3 (right) • For each attenuation value: • 10000 points in each saved data file • Determine background level from mean and σ of points 500-2500 • Determine background subtracted peak height, and apply ± σ • Note that below attenuation ~ 0.3, the pulse becomes hard to distinguish IK/JJ May 6th 2012 Slide 2

  4. Variation of Bunch Charge from FC with Attenuation level • The ‘threshold’ attenuation level required for non-zero bunch charge in EMMA is ~ 0.1 IK/JJ May 6th 2012 Slide 3

  5. Details of data analysis at attenuation value = 0.3 • Pedestal values v4 and v8 are nicely constant, with ~ 1mV jitter • Apparent jitters on horizontal (Xm) and vertical (Ym) beam positions • Apparent systematic variation of mean Xm and Ym with attenuation level (slides 6, 7, 8) IK/JJ May 6th 012 Slide 4

  6. Variation of 4 Summed Pickups with Attenuation Level • Nicely linear with reasonable statistics • Threshold attenuation level again ~ 0.1 IK/JJ May 6th 2012 Slide 5

  7. Horizontal bunch movement with bunch charge (IL-BPM02) • Systematic narrowing of the horizontal spread of positions with increasing bunch charge • Systematic mean movement outwards with increasing bunch charge IK/JJ May 6th 2012 Slide 6

  8. Vertical bunch movement with bunch charge (IL-BPM02) • Indication of downwards beam movement with increasing bunch charge (to Att. ~ 0.7) • Some indication of vertical narrowing (again to Att. ~ 0.7) IK/JJ May 6th 2012 Slide 7

  9. Beam positions at IL BPM-02 with bunch charge • Summarises plots in slides 6 and 7 IK/JJ May 6th 2012 Slide 8

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