CTF 3 Commissioning 26 - AB/OP Quad scan results Dispersion DL length CLIC meeting, 2.6.6
Results III Quad Scans 25 Emittances for 3.5A beam current Injector was not optimised at the beginning. Gain due to the optimisation of the injector (solenoid currents, steering) Emittance (nor, rms) 2 18 16 14 12 1 8 6 4 low quality scans εx - off crest εy - off crest εx - on crest εy - on crest 2 5 1 15 girder How to obtain a better understanding of the measurement results? (I) Girder 5: Scans with opposite polarity of quadrupoles to distinguish if the difference in horiz. and vert. emittance is a beam property or related to diagnostics. (II) - same magnification for beam diagnostic instrumentation in girder 5 and 1. - use quadrupoles in girder 9 for quad scans. (III) Quadrupole scans at the end of the Linac, to obtain a better understanding of the measured emittance values. Collaboration Meeting 29.11.25 Urschütz Peter
> 9 scans done (documented in the logbook) 3 on girder 5 6 on girder 1 27 in the CT line automatic program works well (averaging could be useful) variety of studies done filters/screens scan ranges pulse length transient subtraction Quad Scans 26 CLIC meeting, 2.6.6
Transient subtraction image subtraction of long and short pulse for scans only the steady state part is analyzed Horizontal beam position over the beam pulse CLIC meeting, 2.6.6
Quad Scans Pulse Length Beam transient => Scan results dependant on pulse length image subtraction for long and short pulse for scans (7ns 3ns) + - Girder 1 1 9 8 7 6 5 4 3 2 1 5 1 4 3 2 1-1 alpha em_x betx em_y bety alfx alfy -2 pulse length (ns) CLIC meeting, 2.6.6
Emittance data collection optical magnification on girder 1 as on girder 5 => we measure now also small ε < 5 mm mrad in both planes larger ε values in CT line still ε < 1 µmrad higher energy => smaller beam => optical limit? to be analyzed in detail Emittance (norm. rms) [mm mrad] 25 2 15 1 5 5 1 15 girder 3 SHBs em_x em_y CLIC meeting, 2.6.6
Optics matching (1) Linac rematched based on quad scan results on girder 1 intermediate energies calculated from RF signals results in 71.4 MeV compared to 71 MeV measured CLIC meeting, 2.6.6
Optics matching (2) verified by new scans, expect β=3.4m α=-1.2 measured: β: 2.3 4.5m α: -.8-1.2 => model well established also used for linac downstream CT line CLIC meeting, 2.6.6
Dispersion Measurement (1) measure reference trajectory at nominal magnet settings scale magnets by small amount (~1%) CT Line Delay Loop observe difference trajectory E = 11 MeV Linac + CT Line Delay Loop CLIC meeting, 2.6.6
Dispersion Measurement (2) relative good agreement between model and measurement worse in the second half of DL wiggler mismatch? CLIC meeting, 2.6.6
Dispersion Measurement (3) overall, data for lower currents fits better energy lower than assumed more analysis to be done CLIC meeting, 2.6.6
Residual dispersion Energy change in the linac and difference trajectory Source in the linac mainly chicane on girder 4 Also in vertical plane!? CT line chicane another source 5. 4. MKS3 changed 5. 4. MKS5 changed 3. 3. 2. 2. 1. 1.. -1. 2 4 6 8 1 12. -1. 2 4 6 8 1 12-2. -2. -3. -3. -4. -4. -5. -5. CLIC meeting, 2.6.6
Delay Loop Path Length CD.XHA3 CD.QFF31 CD.QFF29 55 CD.BHF3 CD.WHA35 (CD.DHE29 3 CD.QDF32 CD.VPI36 ) CD.BHE3 CD.QFF35 6 (CD.DHE35) CD.VPI294 CD.BPI38 CD.BHE3 8 CD.XVA3 85 CD.QFF39 CD.BHE4 1 CD.QFE37 CD.BPI378 CD.VPI379 CD.BPI4 CD.VPI413 CD.BPI414 CD.BPI325 CD.MTV331 CD.BPI358 CD.MTV361 CD.BPI292 WIGGLER Delay Loop CD.QDF28 (CD.DVE28) CD.XHA2 45 CD.BPI285 CD.BPI242 CD.MTV241 CD.BPI235 CD.BPI2 CD.BPI186 CD.QFF26 CD.QFF25 CD.QFE23 CD.DHD225 CD.DVD225 CD.BHE2 CD.VPI221 2 CD.XVA21 5 CD.QFF21 CD.BHE1 9 CD.VPI187 CD.BHE2 4 CD.BHE4 5 CT.QDF47 (CT.DHE47) CD.QDF42 CD.QFE43 CT.QFF48 (CT.DVE48) CD.VPI453 CT.BHD49 CD.BPI465 CD.BPI495 CD.QFF46 (CD.DHE46) CD.QDF47 CD.VPI496 (CD.DVE47) CD.XLA455 CD.SHB48 CD.VPI14 CD.SHA49 CD.DHL11 CT.VVS 485 CT.BPI487 CT.DHD495 CD.BPI15 CD.QDF13 CD.SHB12 CD.SHA11 CT.DHD55 CD.BPI135 CD.VPI147 CD.QFF14 (CD.DHE14) CT.VVS 512 CD.QDF18 CD.QFE17 CT.BPM515 CT.BHD51 CT.QDD52 CD.BHE1 5 CD.XLA145 CT. WCM 525 CT.BPR532 CD.DHD185 CD.DVD185 CT.QFD53 CT.BHE54 CT.PHM56 phase monitor CT.MTV55 to Streak Cam. CLIC meeting, 2.6.6
DL path length - BPR DL wiggler has path length tuning range of ~ 9 mm phase measurement on CT.BPR532 after DL change mixer (3 GHz) phase until signal close to (1 2.8 mm) => DL has the correct length within the tuning range Straight BPR: 8 DL wiggler off BPR: 7 DL wiggler 46A BPR: 8 CLIC meeting, 2.6.6
Phase Monitor Developed by Uppsala University To measure phase error in the RF bunch combination T.Lefevre RF Bandpass filter Diodes Digital Oscilloscope 7.5 GHz RF antenna 9 GHz 1.5 GHz e - 12 GHz
Phase Monitor Developed by Uppsala University Pick-up signals with and without the combination (1.5 3 GHz ) RF combination optimization with the Wiggler magnet -1-2 7.5GHz No RF Combination RF combination -2 7.5GHz Wiggler off Wiggler on -3 14 16 18 2 22 24-4 4 6 8 1 12 14 16 18 2 RF Signal Amplitude (mv) -2-4 -6-8 -2-4 -6 9GHz 1.5GHz 15 2 25 15 2 25 RF Signal Amplitude (mv) -4-8 -4-8 9GHz 5 1 15 2 1.5GHz 5 1 15 2-2 -4-6 12GHz 15 2 25 Time (ns) -2-4 Better RF combination 7.5 & 1.5GHz 12GHz 5 1 15 2 Time (ns) 9 & 12 GHz T.Lefevre
RF combination : 11 th May 26 T.Lefevre, C.Welsch SR light in the Delay Loop OTR light downstream the Delay Loop Sweep speed 25ps/mm MTV361 MTV55 4 2 3 15 Light Intensity (a.u.) 2 1 Light Intensity (a.u.) 1 5 5 1 15 2 25 Time (ps) 5 1 15 2 25 Time (ps)
RF combination Wiggler on & off : 12 th May 26 OTR light downstream the Delay Loop @MTV55 Sweep speed 1ps/mm C.Welsch, T.Lefevre Wiggler off Wiggler on 1 75 Bunches from the delay loop Bunch from the linac Bunches from the delay loop later by 12ps (3.6mm) Light Intensity (a.u.) 5 25 Light Intensity (a.u.) 5 5 1 Time (ps) 5 1 Time (ps)
Conclusion Quad scan results show reasonable emittances Dispersion very close to expected values => optics well understood DL loop length correct trajectory measurements to be analyzed verify magnet currents from control system to magnet! Thanks to everyone involved! CLIC meeting, 2.6.6