MD377 Schottky diagnostic M. Wendt, M. Betz, T. Lefevre

Overview Merit Assessing the capability of the Schottky monitors to measure tune, chromaticity and emittance Beam Single Bunch (1.1E11) / Pilot at Injection energy The Schedule 3:00Chroma scan on B2V with a Pilot (2.1E9 ), 4 reference points 3:50Chroma scan on B1H with Nominal (1.2E11), 3 reference points 5:10New fill with 1 pilot and 1 nominal B1 and B2 5:15Emittance blow up on B1H, 4 set-points 5:46Emittance blow up on B2V, 4 set-points 6:05Beam dump Note B2V is equipped with modified frontend electronics which still has problems with gating on 25 ns trains

B2V data, (pilot bunch) Distance between peaks = Synchrotron frequency w HIGH w LOW ΔfΔf How to get Δf, W LOW and W HIGH ? Gaussian curve fit How to deal with the Synchrotron peaks and the Coherent / Incoherent part of the signal? Strong `Smoothing` Coherent tr. signal Incoherent tr. signal

Schottky Tune vs. BBQ Tune B1H (nominal) Top Schottky noise fine-structure (Synchrotron lines) Bottom Schottky Tune result of many curve-fits BBQ Tune from Timber Tune drift RF modulation fsfs

Schottky Chroma vs. RF Modulation Chroma B1H (nominal) Width of Schottky sidebands varies visibly Schottky Chroma result of many curve-fits Ref. meas. Chroma from RF modulation Chroma. setpoints Time Modulation method BUT: ‘Smoothing’ Parameter α = very critical and had to be fine-tuned by hand!

Chroma fit: Needs a lot of fine-tuning Fitting results depend very much on the ‘Smoothing’ Parameter α Fitting algorithm needs more work … Modulation method α = normalized cut-off frequency of smoothing filter α = α = (no smoothing)

Emittance B1H (nominal) From 5:14 – 5:35 the emittance was changed by blowing the beam up with the transverse damper Note the bunch intensity also changed slightly from ~ 1.28E11 to ~ 1.26E11 Emittance from wire scanner Integrated linear Schottky sideband power 2 μm rad μm rad 1778 Linear Scale ! But the relationship needs investigation The power of the Schottky sideband changes visibly with Emittance

Conclusion Proton Schottky signals at Injection are Ok Tune and Chroma information was validated at the MD ≈ 2 min avg. time for one data-point Software (data extraction) problems Current fitting algorithm requires parameter fine-tuning  Needs a lot more work! Emittance measurement  Algorithm not yet investigated Hardware (instrument) problems 25 ns trains saturate the system, especially at Flat top!  Even when gating on a single bunch  Technical problems with single bunch gating (Reflections) At Flat top the Schottky sidebands become very narrow and small  Difficult to curve-fit