2019-04-05

Foil Efficiency

Vacuum successfully applied and lowered to 2.6 x 10^-4 Pa.

All Portals moved successfully, however the holder for the two foils further downstream couldn't be fully inserted anymore meaning one of the foils became unusable. Some blockage appeared to develop while the vacuum was being applied. The cause may be identified once the vacuum is stopped.

The downstream foil holder failed early during testing (the parts that were glued together) while the beam was being characterized likely due the blockage. It fell to the bottom of the pipe but didn't block the Faraday cup. It was also difficult to find a positive current for the first Faraday cup. It was near adjacent to the foil, and may have been too close.

The experiment could only be done with the two upstream foils and the two downstream Faraday cups (JB end and after dipole).

There was major difficulty is focusing the beam to a sufficiently small size as well as the directionality of the beam to ensure it fully hit the foil. The beam in the past had only been optimized for the FFAG ring. The data files gathered are below for the various foil and dipole magnet configurations. The Faraday currents were very low (10^-7 amps) and have been amplified.

The first and last test was repeated showing a major drop off in the current measured by the Faraday cup. This indicates a wide variability in the current during the experiment, meaning the error is too large to tell the difference in efficiency between the foils, with the foils themselves also introducing variability (smoothness, shape, position). The ion source and magnet configurations are other source of error.

The two reverse dipole foil configurations were again repeated in quick succession, they only showed a minor difference however. Again the errors are likely to be far too large to say anything definitive.

File name Upstream Foil Dipole

01All.csv No foil Off

02All.csv No foil Off

03All.csv 8 ug/cm2 Off

04All.csv 8 ug/cm2 On

05All.csv 8 ug/cm2 Reversed

06All.csv No foil Reversed

07All.csv 10 ug/cm2 Reversed

08All.csv 10 ug/cm2 Off

09All.csv 10 ug/cm2 On

10All.csv No foil On

11All.csv No foil Off

12All.csv 8 ug/cm2 Reversed

13All.csv 10 ug/cm2 Reversed