Definition of LST mini-camera tests
Define the tests to be performed with the LST mini-camera set-up: e.g. types of runs to be taken to fully characterise the behaviour of the clusters in terms of cell-wise pedestal levels, noise (incoherent & coherent) , linearity, pulse shape, timing, cross-talk...
A starting point is the draft of the Dragon board V5 quality control, but obviously more types of tests will be possible with the mini-camera test set-up featuring 19 fully equipped clusters.
The procedure should include tests in which the clusters work in conditions as close as possible as those expected in actual operation: for example, runs in which the readout is triggered not at a regular frequency, but at random like in a Poisson process.
Updated by Nakajima Daisuke about 6 years ago
The following is the list of the measurements we are planning
- Gain of all PMT (Single photon response at HV=1500)
- HV vs Gain
- Flat fielding of PMTs to the nominal voltage computed from 1),2)
- Linearity of PMTs(+all amplification chain)
- Pulse shape
- Long term linearity ( monitor gains for a week)
In order to perform the test listed above, we need to study the fundamental pedestals of DRS4.We already know that the fundamental pedestal depends, at least, on
- Capacitor ID
- Position in ROI (or distance from the stopcell)
Current idea is to take the pedestal data by means of an Dragon internal trigger.
We can choose the internal trigger frequency such that they are perfectly synchronised with the domino wave, which means that the delta-t dependence is always the same.
One example is to take data at 4 different trigger frequency, each differs by 132 clock cycle, and 132 different trigger offset.
By changing the trigger frequency by 132 cycles, we change stopcell by 1024
By changing the trigger offset by 1, stopcell will move by 7 or 8.
(1 clock cylcle corresponds to 7.5 ns (133MHz))
In total 4*132 = 528.