On 23/02/2018:

We moved the target ladder to position 7, 5.019mm, with the alpha source facing downsteam.

At 17:17 we started the DAQ for a 15 minute alpha spectrum on the downstream S2. Save name: /Remote_Objs/RData_1/180223172135

The trigger rate ~ 160 Hz, Event Mult. = 5.8, Dead time = 0%

Note: For both this alpha spectrum and the beam measurement at 3.45 MeV 7Li (See entry #20) the pulser test input was also plugged into the diode preamp, hence the pulser peak appears at a lower channel in the S2 spectra. It still does not overlap the alpha peaks.

See attached "180223_Alpha_S2FrontStrip_ADC2CH20.png" for sample alpha spectrum of front S2 strip

See attached "180223_Alpha_S2BackStrip_ADC4CH24.png" for sample alpha spectrum of back S2 strip

In the S2 front strips we observed some additional peaks at lower channels ,~500, to the alpha peaks, but were unsure what they were. We decided to run a background to confirm whether this was caused by the source.

We moved the target ladder to position 1, 95.010mm, to position the alpha source as far from the central beam axis as possible. We then collected a background run for 5 minutes 16 seconds. Save name: /Remote_Objs/RData_1/180223174450.

We did not observe these low channel peaks in the background run, suggesting they are the result of the alpha source - perhaps a geometry effect.