Commissioning of the Aramis undulator line @ 3GeV FLAC XV Commissioning of the Aramis undulator line @ 3GeV Marco Calvi February 2, 2015, Villigen PSI

Overview Preparatory work at the MML BBA to define the reference orbit Commissioning with electron beam Alignment of the undulator modules Correction of the residual U15 field errors Commissioning with photon beam Fine-adjustment of the height and pitch In situ calibration of the individual K-values Pointing direction: checks and corrections Setting up of the phase shifters FEL signal characterization Pulse energy (absolute) and its statistic Gain length per module Conclusions

Preparatory work @ MML U15 Phase Shifter Alignment Quadrupoles Optimization of the trajectory and phase of the U15s Calibration of the K versus gap: gn(K) Measurements of the residual 1st and 2nd field integrals versus K: I1n(K) & I2n(K)  inδn(K) & outδn(K) Phase Shifter Optimization of the field integrals Phase shift versus gap calibration: gn(ϕ) Alignment Quadrupoles Check the Gdl and the reproducibility of the transversal positioning Magnetic alignment on the U15 axis

Phase shifter

Alignment Quadrupoles

Aramis Beam Based Alignment Corrector-based BPM alignment (Aiba & Böge FEL 2012) Procedure Steer the beam to the centres of BPMs and record the corresponding corrector strengths (strong correction indicates large misalignments) Find BPM positions that minimise the deviation of corrector strengths Corrector strengths will be all zero if no misalignments and no error field A running orbit feedback simplify the above procedure Features Random error field dependent (undulator error fields must be small) No momentum change is required and thus quick Corrector strengths must be the same value for periodic line

Overview Preparatory work at the MML Run BBA to define the reference orbit Commissioning with electron beam Alignment of the undulator modules Correction of the residual U15 field errors Commissioning with photon beam Fine-adjustment of the height and pitch In situ calibration of the individual K-values Pointing direction: checks and corrections Setting up of the phase shifters FEL signal characterization Pulse energy (absolute) and its statistic Gain length per module Conclusions

Undulator alignment

Undulator alignment

Undulator alignment

Undulator alignment The upstream & the downstream alignment quadrupoles can be used independently to define the x & y positions at the two extremes Later the x , y , pitch & yaw position of the U15 module can be calculated and the undulator moved to the new position Finally the alignment quadrupole can still be used to check and to verify the stability with time

Field Error Corrections

Field Error Corrections

Field Error Corrections

Overview Preparatory work at the MML Run BBA to define the reference orbit Commissioning with electron beam Alignment of the undulator modules Correction of the residual U15 field errors Commissioning with photon beam Fine-adjustment of the height and pitch In situ calibration of the individual K-values Pointing direction: checks and corrections Setting up of the phase shifters FEL signal characterization Pulse energy (absolute) and its statistic Gain length per module Conclusions

Photon diagnostic Front end slits for shaping the white beam Double crystal monochromator (2.1-20.0keV) with a bandwidth of about 10-4 Photo diode for pulse energy MCP for low intensity pulse and profile monitor

Height and pitch adjustment T.Tanaka et al. Phys. Rev. ST Accel. Beams 15, 2012 Set all undulator at open gap Set the undulator n at K=1.2 Set the monochromator at E(K) Move the undulator height around the nominal position and measure the photon flux K=K0+αh2 The axis is defined by the magnetic field symmetry If the g(K) relation is correct the axis has also the highest photon flux

g(K) value calibration T.Tanaka et al. Phys. Rev. ST Accel. Beams 15, 2012 Set all undulator at open gap Set the module n at K and the monochromator at E(K) Move the undulator gap around the nominal value while recording the photon flux When the blue edge of the spectrum is well characterized the actual gap shall be extracted using empirical fits

g(K) value calibration

Photon pointing direction T.Tanaka et al. Phys. Rev. ST Accel. Beams 15, 2012 Set all undulator at a given K value Shift the module n to K+ΔK and set the monochromator at the energy E(K+ΔK) Use MCP+FS respectively to amplify and detect the profile of the pulse on a CCD This procedure shall be repeated for all modules (and eventually also for different K) The steering magnets shal be tuned to improve the overlap of the different sources

Setting the Phase Shifters T.Tanaka et al. Phys. Rev. ST Accel. Beams 15, 2012 Set all undulator at open gap Close the modules n and n+1 at K Set the monochromator at the energy E(K) Change the phase shift between from maximum to minimum This procedure shall be repeated for all phase shifter modules (and eventually also for few different K)

Overview Preparatory work at the MML Run BBA to define the reference orbit Commissioning with electron beam Alignment of the undulator modules Correction of the residual U15 field errors Commissioning with photon beam Fine-adjustment of the height and pitch In situ calibration of the individual K-values Pointing direction: checks and corrections Setting up of the phase shifters FEL signal characterization Pulse energy (absolute) and its statistic Gain length per module Conclusions

Pulse energy Courtesy of E.Prat All undulator set at a given K value (eventually with a taper) Record the pulse energy on a single slot base Build up the statistic: Average pulse energy (mJ) Number of excited modes

D.Ratner, Proceedings of the FEL2009, Liverpool, UK Gain Length D.Ratner, Proceedings of the FEL2009, Liverpool, UK Set all undulator at open gap Close the first module to K and record the average photon flux Close also the second to K and record the average photon flux …. Repeat until all the modules are closed to K

Conclusions The general ideas for the commissioning of the Aramis undulator line have been presented A preliminary procedure has been internally discussed among different groups and the hardware as well as the timing have been verified In the coming months a more detailed procedure shall be written down and finally approved

Thanks for your attention!