Phone Meeting: BPMs and "Al" peaks (02/20/2009)

Carbon spectra for runs at different scattering angles:

1.)

Remaining Problem: Aditional peaks appear in the C-single and Ta runs, while there is no additional peaks in the Optics 7-foil target runs. What is the origin of these additional peaks?

Hypothesis: I suspect that these additional peaks in the middle of the momentum spectrum are caused by those electrons that scatter off the aluminium framework and an aluminium "ring" that holds target in the place and is attached to the framework from behind.

BPM:

How was the position of the beam changing during runs:
There are runs with up to 4mm horizontal beam offsets from the centre position.

2.)

X - horizontal axis
Y - vertical axis

3.)

Runs with bigger beam offsets have smaller ratio (elastic peak)/ ("Al" peaks) than those with smaller beam position offsets.
This indicates that beam might be hitting some Aluminium.

Correlation between the BPM.Y offset and ratio (elastic peak)/(second Al peak)

Example of Ta run:

4.)

Example of C-single foil run:

5.)

Results of my analysis:

6.)