1. P. Pakhlov (for D.Liventsev)
Read out electronics
P. Pakhlov (for D.Liventsev)

2. Test of the SiPM read out by evaluation board provided by Gary
1 kOm
1 GHz
SiPM signal with LED (5 p.e.)
A p.e. ~ 2 units (1.2 mV)
Noise spectrum:
besides random noise some structures are seen (x-talk of digital  analog part?)

3. Estimate random noise: distribution of difference between two succesive measurements (1 nsec)  RMS ~ 2 units;
The toy MC shows that with random noise only the p.e. peaks should be resolved with the fit A(t) distribution: σA ~ 0.6 units,
The fit from the (pedestal) data σA ~ 1.7 units
Fourier analysis finds no specific frequency of noise
A from the fit with LED (Np.e. = Poisson with 3.7 p.e. mean):
p.e. peaks are not resolved, however the signal are certainly seen
pedestal,
A from the fit
threshold

4. Working with simple preamplifier, gain ~ 15
Working with simple preamplifier, gain ~ 15. The noise is not increased, The signal is 30 units/ p.e.
To use the borad dynamical range (-500 – 500 units) the gain should not be larger than 15.

5. With preamplifier: P.e. peaks are seen even without LED (SiPM noise)
In LED spectrum (mean 4.2 p.e.) the p.e. peaks are nicely resolved.
Time resolution (even with 4 p.e. only) is better than 1 ns, this is very important for fake KL rejection + provide time of flight measurement for slow KL

6. Conclusion
The universal read out board is appropriate for our tasks, some improvements are still required: either reduce the internal noise (differential input should help a lot) or(and) to amplifiy the SiPM signal
X-talks between channels are measured and consistent with Gary’s note ~ 2-5% (not a big problem, but it is better to reduce them)
HV ajustment is required. Can it be implemented in the read out board?
Can we place read out board to the iron gaps near SiPM:
reliability, ageing?
heating?
optimization of geom. size?