2019-12-05

Foil Experiment

14:30

Vacuum levels in the main ring have improved considerably overnight. The leak near the upstream foil may have caused significant gas stripping of the beam yesterday explaining why the Faraday cups were measuring such a large positive current.

It would still be interesting to know why leak in the vacuum near the upstream foil before the dipole magnet, coupled with a dipole magnet current of 9 amps (~165 amps causes a 45 degree rotation of the beam) would cause a momentary negative current before returning positive in Faraday Cup 2.

After some checks, the Faraday cups along with the fluorescent screens in the beam line behaved as expected and the foil experiment began. Each run was repeated 10 times, with each data run being an average of 512 samples. After run tek0084.csv the linac failed momentarily, so the beam may behave differently from that point on. The reversed dipole data will be taken after lunch with the filename runs added later. The Channel number corresponds to the Faraday cup.

17:30

The rest of the foil data has been collected. No problems to note with the data taking going as planned. The pressure level was approximately 1-2 x 10^-5 throughout the data taking.

The run with both foils in and the dipole magnet switched on was repeated twice, moving the upstream foil further left. It had been suspected some high energy H- particles may have missed the foil. Analysis will tell if that is the case, or if they were indeed left unstripped.

Single Wire Experiment

Everything has been extracted from the beamline and the main ring is being prepared for the single wire experiment. It is expected that the condition of the beam will be checked in the evening, and actual data taking may not commence until tomorrow.

Experiment Setup

Location Setup from March/April run. This time only one foil was used both upstream and downstream. The upstream movable Faraday cup is Faraday Cup 1 (CH1), the stationary downstream Faraday Cup is Faraday Cup 2 (CH2) and the movable Downstream Faraday Cup is Faraday Cup 3 (CH3).