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TCDI setting-up beam tests - PowerPoint PPT Presentation

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TCDI setting-up beam tests

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  1. TCDI setting-up beam tests W.Bartmann R.Assmann, C.Bracca, B.Goddard, V.Kain, S.Redaelli, A.Rossi, D.Wollmann, … TI2/TI8 Tests Result Meeting, 9-Oct. 09 ~6 hours with p+ (5e9 and 1.2e11) ~4 hours with Pb 82+ (9e7 ions)

  2. Beam centering/size with 5e9 p+ • TCDIH.29050 • Scan of jaw position and fits to find centre and sigmas • Done ‘online’ in CCC with Chiara’s script • Loss measurements not normalised to intensity • BLM.29053: sigma 0.71 mm, centre 0.00 mm • BLM.29104: sigma 0.72 mm, centre 0.07 mm • Beam sigma expected from 6.3 nm emittance: 0.76 mm BLM.29104 BLM.29053

  3. Beam centering/size with 5e9 p+ • TCDIV.29012 • Scan of jaw position and fit to find centre and sigmas • Done ‘online’ in CCC with Chiara’s script • Loss measurements not normalised to intensity • BLM.29012: sigma 0.32 mm, centre 0.35 mm • BLM.29053: sigma 0.23 mm, centre 0.31 mm • Beam sigma expected from 3.4 nm emittance: 0.32 mm BLM.29053 BLM.29015

  4. Beam centering/size with 1.2e11 p+ • TCDIV.29012, BLM.29015 • Scan of jaw position and fit to find centre and sigmas • Sigma 0.22 mm, centre 0.40 mm

  5. Beam centering/size with 1.2e11 p+ • TCDIV.29012, BLM.29053 • Scan of jaw position and fit to find centre and sigmas • Sigma 0.18 mm, centre 0.34 mm

  6. Beam centering/size with 9e7 Pb82+ • TCDIV.29012, BLM.29015, blue: with intensity normalisation • Scan of jaw position and fit to find centre and sigmas • Beam size 0.21 (0.19) mm, centre 0.07 (0.04) mm

  7. Beam centering/size with 9e7 Pb82+ • TCDIV.29012, BLM.29053, blue: with intensity normalisation • Scan of jaw position and fit to find centre and sigmas • Beam size 0.17 (0.17) mm, centre -0.02 (-0.04) mm

  8. Tail scan with ~1.2e11 p+ • Jaws set around derived beam centre • Jaw opening increased in steps • Very significant exponential beam tails…

  9. Angular scan scan with ~9e7 Pb82+ • Jaw angle varied with Pb82+ beam impacting • Minima found at 0.153, 0.109, 0.087 mrad • Average of 0.1160.034 mrad • Does not look very accurate (broad minima)

  10. Losses normalised to measured intensity? • Sounds like a good idea…. • Problem is poor resolution of TT40/60 BCTs with low intensity – for 5e9 p+ the noise on the intensity measurement is generally larger than the intensity fluctuations of the beam. • Should be much more accurate for 1.2e11 p+ (noise ~1%) • But saturation of BLMs seems to occur for 100 mGray TCDIV, 5e9, normalised to BCT signal TCDIV, 5e9, not normalised to BCT signal

  11. Trajectory Scan Trajectory scanned about TCDIH.29050 (-5 to +5 mm) and TCDIV.29012 (-2 to +2 mm) Centering looks reasonable

  12. Comparison: p+ –Pb82+ at 5e9 charges Ions BLM.29015 p+ BLM.29015 Ions, norm. BLM.29015 Ions, normalised to intensity and number of nucleons (2e10)

  13. Comparison collimator settings for different proton intensities BLM.29015 – 1.2e11 BLM.29015 - 5e9 • Saturation of BLMs • Max loss only factor 5 higher (intensity x20) • Moves crossing point upwards • Centering should not really be affected • Would tend to artificially make measured sigma smaller

  14. Summary table