LED calibration device

AbstraktAbstract

The device was developed for energy calibration of pixel detector Timepix working in Time-Over-Treshold mode. The calibration method is based on pulses of visible light provided by flashing LED diodes. The intention is to simulate the strong ionization caused by single ionizing particle such as X-ray photon by multiple small ionizations made by many visible photons interacting within a very short time interval. For this purpose, the matrix of 64 diodes in 8 x 8 configuration is used. The collection of calibration data is performed sequentially scanning the entire detector using these LEDs one by one for each selected pulse width. Device is driven by 8-bit AVR microcontroller ATmega by Atmel and communicate with PC via USB to serial UART interface (FT230 by FTDI). For selection of particular LED two analog multiplexers driven by the microcontroller are used. The internal 3.3 V or external power source can be used for settings the amplitude of the pulses. To control the duration of the pulses there are also two options, the first one is to use external pulse generator and the second one is to generate them internally by microcontroller (in scale from 83.3 ns up to approximately 20 ms using 12 MHz crystal).

The device was developed for energy calibration of pixel detector Timepix working in Time-Over-Treshold mode. The calibration method is based on pulses of visible light provided by flashing LED diodes. The intention is to simulate the strong ionization caused by single ionizing particle such as X-ray photon by multiple small ionizations made by many visible photons interacting within a very short time interval. For this purpose, the matrix of 64 diodes in 8 x 8 configuration is used. The collection of calibration data is performed sequentially scanning the entire detector using these LEDs one by one for each selected pulse width. Device is driven by 8-bit AVR microcontroller ATmega by Atmel and communicate with PC via USB to serial UART interface (FT230 by FTDI). For selection of particular LED two analog multiplexers driven by the microcontroller are used. The internal 3.3 V or external power source can be used for settings the amplitude of the pulses. To control the duration of the pulses there are also two options, the first one is to use external pulse generator and the second one is to generate them internally by microcontroller (in scale from 83.3 ns up to approximately 20 ms using 12 MHz crystal).