September 7/04Cyclotron Development Meeting. Improvement TOF Possible TOF improvements

September 7/04Cyclotron Development Meeting. Improvement TOF 1. On the previous shift quite a strong “noise” ~1-3  sec in TOF measurements was observed 2. A series of checks was suggested: - Check beam timing on the ISIS exit - Crosscheck TOF given by the discriminator and TDC with the scope - Effect of the beam acceleration and acquisition conditions on TOF noise and accuracy

September 7/04Cyclotron Development Meeting. Improvement TOF Signal from ISIS Time jitter < 10-20ns

September 7/04Cyclotron Development Meeting. Improvement TOF - Measurements were done at three values of radius. - Good stability and low jitter were observed - Rise time of the pulse ~1.2µsec Radius: 147 ‘’ 212’’ 309’’ Jitter, ns: <30 <40 <50

September 7/04Cyclotron Development Meeting. Improvement TOF On the other hand a two-peak time structure was observed depending on - Probe radius - Beam phase width (flags) - Center beam phase Second peak was jittering a lot

September 7/04Cyclotron Development Meeting. Improvement TOF R=147” R=212” R=309” Time of Flight

September 7/04Cyclotron Development Meeting. Improvement TOF R=147” R=212” R=309” Noise spectrum

September 7/04Cyclotron Development Meeting. Improvement TOF Variation in time of flight may be caused by -variation in energy gain per turn: rf amplitude, phase and frequency -betatron oscillations ~10 -4 is a good stability Spikes are removed Averaging may help in reducing random noise. Mike Mouat looks into problems related to controls Quantization minimum 43nsec is natural for this system

September 7/04Cyclotron Development Meeting. Improvement TOF 1. Acquisition electronics likely behaves reasonably good 2. Most of the noise comes likely from beam fluctuations but small when the beam quality is good 3. Let’s look at TOF (R) 1.Convert R to E 2.Following Larry Root split TOF in LMS linear fit and “fast” varying part: Tof(E) = aE+b + V(E) 3.Apply smoothing to V(E) 4.Differentiate V(E) 5.Find Vcos

September 7/04Cyclotron Development Meeting. Improvement TOF -R to E conversion is not perfect? -Betatron oscillations reproducible on tof - Spikes nature ? - Noise at reasonable level

September 7/04Cyclotron Development Meeting. Improvement TOF Cubic Spline smoothing minimizes Advantage: one later differentiate a continuous function

September 7/04Cyclotron Development Meeting. Improvement TOF

September 7/04Cyclotron Development Meeting. Improvement TOF

September 7/04Cyclotron Development Meeting. Improvement TOF Normal conditions Flags inserted Flags out, bunchers off Data from 04/07/13

September 7/04Cyclotron Development Meeting. Improvement TOF 04/07/27 04/07/13

September 7/04Cyclotron Development Meeting. Improvement TOF Conclusions TOF noise observed in the previous run was not detected, but almost for sure came from the beam itself. Electronics behaves reasonably well. If further increase in resolution is needed the whole thing is to be redesigned : impedance match, amplifiers, constant fraction discriminator, TDC, higher rf harmonics but this may not reduce noise Instead, averaging may reduce it Mystery spikes but can be easily smoothed out but one can may look at origins Some kind of smoothing is unavoidable before differentiating. Spline smoothing helps in reduction of Vcos noise.

September 7/04Cyclotron Development Meeting. Improvement TOF Near-future plans Piece of electronics for TOF at BM1A Constant fraction discriminator test RF harmonics test Spike hunting Phase capacitive probe reanimation (money for cables) Wide band head for HE3. It is planned for winter shutdown.