- Typ
- Masterarbeit
- Gebiet
- Detektorentwicklung
- Autor
- Alexander Deisting
- Titel
- Readout and Analysis of the Induced Ion Signal of an InGrid Detector
- Datum
- 2014-08
- Reportnummer
- BONN-IB-2014-10
- Kurzfassung
- The CERN Axion Solar Telescope (CAST) searches for axions, converting in a magnetic field into
low energy X-rays. In order to detect such X-rays a detector is needed which is capable of measuring a low rate of photons with small energies. Furthermore a clear distinction of signal events originating from photons and background events due to charged particles should be possible with this detector.
A gaseous detector matching this requirements was developed in Bonn. During their detection
X-rays will create electron-ion pairs inside the detector volume. The electrons are then amplified in a Micromegas-like gas amplification stage and afterwards read out with a pixel chip. More precisely this setup consists of a Timepix ASIC with a small micro-mesh (InGrid) on top of it. Mesh holes and pixels of the chip are aligned with each other, hence the electron avalanche created by a primary electron will be detected by only one pixel.
In the course of this thesis this setup was extended with a readout of the induced ion signal on the InGrid. The decoupled signal was digitised with an flash-ADC and synchronised with the readout of the Timepix ASIC in order to match the pulses on the grid with the actual event. Based on different data samples recorded with the upgraded detector the decoupled signal was analysed.
The general response of the different preamplifiers to the input signal was examined. It was investigating as well if the simultaneous readout of chip and grid would improve the background suppression of the detector.
Using a 90Sr and a 55Fe source it was possible to find differences in the pulse shape originating from charged particles and X-rays. Finally these results were discussed as to the operation of the detector at the CAST experiment. The statement was made that the use of the decoupled signal could further improve the background suppression of the Bonn CAST detector.
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