Tuesday 1st April 2014

Post date: Apr 1, 2014 10:03:27 AM

Morning meeting:

Chris R has arrived and is now in the lab too from today until Friday.

Ishi-san gave a quick update on the 'kink' observed in S7-up plate data. The timing of the kink is the same for various settings on 26/3 and its always the same so perhaps it's just electronic noise. Could be some kind of leakage beam from the chopper.

We discussed scheduling & timing of different experiments. For the horizontal dispersion matching/orbit matching will need to open the vacuum to put in a slit in order to select out only a small beam. We might also use this in the energy loss measurement if we need a small momentum spread beam.

Discussion about energy loss on foil measurement:

1. Measurement of radius degradation as a function of time is hard**

Without RF the longitudinal spread of the beam comes on quicker than the transverse spread**

With RF, RF bucket height >> energy loss, energy loss turns into a small longitudinal emittance growth

2. Measurement of time of flight is also a problem for the same reason

3. Maybe there is a way by altering the RF phase to cause 0 energy growth**

Work with synchronous RF voltage to capture the beam with no energy change**

Lower the RF voltage so that we have a smaller bucket area

Uesugi-san also gave an update on the measurement of the real k value over the energy range.

He used a set voltage threshold script to find the time vs radius from 31/3/14 data.

It is important to normalise the timing offset of the system. To find correct frequency in t vs f file need t+93.28musec for this set of data. We discussed the analysis and more info to come.

After lunch Mori-san made an interesting presentation about muon nuclear transmutation for us to discuss.

He also presented some previous work at Kyushu university on tune measurement in the other (similar) 150MeV FFAG there.

Today we will take tune measurement data for horizontal and vertical tune with working point and with energy. We have been setting the machine up for this during the afternoon. The ion source filament is struggling a little bit. The team installed the vertical perturbator and have mixed in an RF pattern to perturb the beam horizontally at the same time. We are using a flat-top after the beam has accelerated to about 12.3 MeV after the beam has moved off the foil then we apply the perturbations and will take the data for the tune measurements.