Detector Operation and DAQ Setup
Detector operation
Operating the detector occurs by providing voltage to the connected HV-circuit the detector components mentioned in the previous section. A CAEN N470 four channel power supply is used for this purpose, using a channel of the power supply allows to increase the voltage difference between the top and bottom side of the first GEM preamplifier reaches up to 350 V then voltage gradually decreases to be the least for the third GEM preamplifier, as the circuit board is directly provided by a voltage of 2.8 kV from the power supply.Another channel of the power supply is used to increase the voltage of the Cathode. When the cathode voltage is 3.1 kV to create a drift voltage of 300V in the drift area.
The power supply is connected to a discharge protection circuit. CAEN N470 has a signal Lemo 00 input to activate a kill option automatically when a discharge signal occurs through the detector operation, the kill input is connected to the detector charge collector output, so as a discharge happens and its signal wider than 15 us, kill option state turns true, so it will trip all the power supply channels.
The detector distinguish between the neutron signal from the other particles' signal by analyzing the data as the detector's shutter is open and as it is close. GEM detector has the ability to detect most of the signal created by the particles if they cause ionization in the gas in a rate of 5 MHz, so the detector detects the signal of electrons, Bremsrahlung radiation, and neutrons. The neutrons' signal is distinguished in comparing two runs; one run records the detector signal as the detector's shutter is open, and the second run records its signal as the shutter is close. Within a common known time period, the difference between the two signal represents the neutrons signal.Testing the ability of the shutter to stop the fission fragments is confirmed by being able to stop the alpha particles produced by U-233 that is installed inside the detector and showing a difference in the Q-ADC spectrum between the shutter positions.
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