QADC spectrum

QDC Analysis

details proving signal is from detector ON/OFF

details of measuring shutter OPEN - Closed (why negative counts????)

Detector Charge Spectrum

The detector has been tested after installing U-233 and its shutter using CAEN V792 Q-ADC (Analog charge to digital converter). The detector design has been modified by adding U-233 and an FR4 shutter as mentioned in sections xx and yy. To observe a signal for the alpha particles emitted by U-233, an input voltage was 2.6 kV and 2.9 kV for HV-divider circuit and the cathode successively. The output of the trigout goes through the electronic modules then to the DAQ system as mentioned in section x. the following figure show the charge spectrum collected by the DAQ system.

charge collected as the voltage is 2.60 2.90 kV for GEM and cathode successively

The figure shows the charge spectrum as the shutter is open (red), shutter close (navy), and the difference between them (blue), it also shows that the charge is almost 27% higher as the shutter is close than that of the shutter is close. The same results are observed as the voltage on GEM preamplifiers gradually increases to 2.9 kV by 50V increment as shown in the table below:

charge collected as the voltage is 2.60 2.90 kV for GEM and cathode successively

charge collected as the voltage is 2.65 2.95 kV for GEM and cathode successively

charge collected as the voltage is 2.70 3.00 kV for GEM and cathode successively

charge collected as the voltage is 2.75 3.05 kV for GEM and cathode successively

charge collected as the voltage is 2.80 3.10 kV for GEM and cathode successively

charge collected as the voltage is 2.60 2.90 kV for GEM and cathode successively

charge collected as the voltage is 2.65 2.95 kV for GEM and cathode successively

charge collected as the voltage is 2.70 3.00 kV for GEM and cathode successively

charge collected as the voltage is 2.75 3.05 kV for GEM and cathode successively

charge collected as the voltage is 2.80 3.10 kV for GEM and cathode successively

A Non-linear increase in the charge collected by the Q-ADC as the voltage increases for GEM HV-circuit, also the figures show the change in the charge spectrum as the shutter position changed, shutter open's charge spectra show more collected charge than that of shutter close.

GEM voltage vs. the charge of the peaks appear as the shutter is open (blue, green) and close (red)

GEM voltage vs. the reltive gain of the peaks appear as the shutter is open (blue,green)and close(red)

First Peak in Shutter open spect

voltage (kV)	channel number for three runs	charge calibration factor	Charge (nC)	Average Charge from the figure (nC)
2.75	1143+_3 ,1274+_3 , 1026+_3	0.0393	45.11	50
2.80	1078+_2, 1015+_2, 1110+_1	0.051	54.45	50

The table above shows a comparison between the averaging 3 charge spectra to find the channel number for the first peak as the shutter is open (last column), and a gaussian fitting for each peak for each run separately to find the average, then calculating the average for the three peaks' channel number (column 3). The comparison shows that the first peak is still considered saturated.

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