Test of the FADC/DAQ
system
This page contains a short description of some tests performed with
the MAGIC data acquisition chain and links to some sample data files
produced during these tests.
First calibration pulses taken with MAGIC camera
in the night of 02.04.03 the first pulses from the LEDs in the calibration
system have been seen in the MAGIC camera and recorded with the FADC
system.
The camera has been operated at 1000V for the outer pixels and 1100V for the
inner pixels. The calibration LEDs (several different color combinations) have
been firing at 500-1000 Hz. Clear pulses could be observed
(
sample pulse 1 and
sample pulse 2). Currently 1 (out of 6) sector of the camera is
connected via optical cables to the readout system (pixels with charge in
camera display). The trigger and the FADC system worked as expected.
A glimpse of the chronology of the night you can find in
the logfile.
Here are some
root files (MARS format) mentioned in the log-file. You can also
have a look at
raw data files to test merpp (the raw files may only contain
pedestal data).
Feel free to have a look at it and try out your analysis tools. However have
in mind that they are very preliminary data. There is no calibration nor
flatfielding done and there might be bad connectors, wrong pixel assignment
etc. involved.
Test of full MAGIC data acquisition chain
(PMT->optical link->receiver board->FADC->DAQ) in Munich
The setup in Munich includes the following components:
- blue LED, ca. 2nsec wide light pulses, rate ca. 1kHz
- PMT (1", EMI 9116A) with final MAGIC PMT base including
trans-impedance pre-amplifier
- attenuator (optional)
- optical link (VCSL + optical fiber)
- receiver board (shaping, high/low gain amplification)
- FADCs (typically 8 channels read out / 32 channels available)
- DAQ (PC with MicroEnable PCI card)
For most of the test, the PMT HV was set to 1100 V and the PMT pulse
was attenuated in steps of 5dB before the optical link. Here are some
example root
data files and the corresponding raw data
files. There are only pulses in channel no. 1 (out of 8).
The results of a preliminary analysis are summarized
here.
The charge has been obtained by summing up samples 3..14 and the
pedestal value has been extracted from the file with an attenuation of 100
dB. The effect of saturation can clearly be seen in the linearity
of the high gain signal. Not completely understood is why the low gain
signal is not fully linear for high input pulses.
A typical noise pattern can be found in the analysis of a different FADC
channel . This "alternating noise" is know but not really
understood yet. However, when integrating an even number of samples
(as done here) the effect mainly cancels out.
The FADC response as a function of PMT HV can be found here