We have gotten 15 PMTs from Michael Heil and Carsten Brandau which we want to use for the NEEC Particle detectors. Therefore, we tested them for damages and to see their comparative 
properties. 
We have built a setup in which the PMTs lie in front of a scintillator (BC420) and an alpha source in a dark box. The alpha source was in a separate box, where the alpha particles 
could only stream out trough a slit.
We applied a voltage of 1206 V and observed the signals on an oscilloscope and took histograms for 1 min to see the distribution of the signal sizes.
See attached picture (standard setup) for details of the setup (blue box is the alpha source, black tube the PMT, the scintillator plate is in between).

The test results are stored in the attached root file.
The calibration of the high voltage module and the results of the PMT tests can be found under this link:
https://sf.gsi.de/f/7d1bf3c9c7124d75b1ff/
There are slight differences in the size of the signals. In general, all of the PMTs seem to perform well.

On some PMTs there were residuals of glue which we cleaned. For PMT10 and PMT12 there are two histograms: Messreihe_1 was with the glue and Messreihe_2 without.
We see that there are more signals after they were cleaned.

We had multiple measurements for PMT14 before.
The first was with the cap on it and without any other sources.
The second with the scintillator (as a packed stack) right in front of it.
The third with the scintillator (as a packed stack) and a alpha source close to the PMT14 but above of the scintillator. (see picture, packed setup) 
The fourth with the scintillator (as a packed stack, but without a protective foil right in front of the PMT) and a alpha source close to the PMT14 but above of the scintillator. 
The last to measurements where with the scintillator (single plate). One withe the alpha source close and one where the alpha source was on the other side of the scintillator. (see 
picture, standard and alpha source far)
With the standard setup we saw a clean peak from the alpha particles.
when the source was far away there was no peak visible.