Post date: Mar 28, 2014 10:54:44 AM
Suzie showed a small update to the dispersion analysis for the ring where she calculated the dispersion as a function of radius (or momentum) rather than just finding a single average value. (slides/further discussion forthcoming...)
Real K method and RF optimisation - Monday/Tuesday
Ishi-san is out of the lab Monday morning, so Uesugi-san will lead the k(r) measurement using radial probes (like COD measurement method) using fine steps especially at low energy (1cm?) as this is required to get a good fit for the rf programme. (Monday & then implement new RF programme on Tuesday?)
Ishi-san showed us a 'kink' in the bpm response at 2.7E-5 which may be a secondary electron or proton effect. The 'kink' timing depends on tune.
Analysis to do:
Check the position of the kink as a function of initial coherent oscillations in vertical (using ST5 tuning knob). Dataset eg. 2014-03-26 tune measurement data F773.3_D0_D1020 F7up foil position 76
If it doesn't change, might just be electronics...
Analysis to do:
measure the beam size by measuring the radial-probe method data beam loss slope. Do the same thing for 3 different probes to see the beating of beta function.
Horizontal orbit optimisation - weds
"matched" may not = "optimised"!
Empirically fitted at present seems pretty good.
In terms of dispersion and optic functions it's not necessarily optimised. There are only 3 tuning 'knobs'. We will develop the procedure.
Tune measurement - thursday
First we need to measure the timing of the points of fast beam loss so we avoid 'sitting on them' with a flat-top!
NB can't measure with probes all the way to extraction (up to 90MeV or so due to probe range).
If we add an extra frequency modulation and the horizontal triangle plate monitor (use a flat-top) we can measure the tune (observing sidebands) without installing the perturbator.
Friday:
We'd also like to include energy loss from the foil measurement when Chris R is here but we need to think about how to measure the radial shift due to energy loss (as the beam spreads out longitudinally very quickly compared to the time for a considerable beam movement). We can't get a proper readout of the triangle plate bpms as the signal varies depending on position (due to triangle shape), beam loss and spreading out.
Method 1:
We would have to use a probe from inside radius otherwise we block the circulating turns!! We have one probe installed on the inside of the ring.
Method 2:
Also discussed an RF-based method using flat top outside the foil to calibrate and a flat-top on the foil to measure deltaPhi and V -> dE.