RT Improvement by Post-Processing

• bunch of charged particles excites damped oscillation in electronic circuit of the RT
• oscillation amplitude is proportional to total charge of particle bunch
• existing GSI RT: signal fed to peak detector prone to noise at maximum position
• large dynamic range: ~ 120 dB.
• typical resolution: ~10 pCRMS (6×10^7 protons)
• for high current operation resolution drops to 100 nC (6×10^11 protons)

→ insufficient e.g. for transmission control

[from: “A High Stability Intensity Monitoring System”, M.A. Clarke-Gayther, RAL, Didcot (UK), presented on EPAC, Sitges (E) 1996]

Courtesy of A. Reiter

• idea: : resonant frequency ω0 and decay time constant λ, are fixed by hardware
• omission of inexact peak detector

→ improved RT resolution by digitization of oscillation data, FFT filtering and envelope fit

• FFT filtering and offset correction
• identification of maxima and minima until preset S/N value crossed
• robust estimator of exponential decay curve
• evaluation of amplitude ~ total pulse charge