Dissertation / PhD Thesis

GSI-2019-00703

http://join2-wiki.gsi.de/foswiki/pub/Main/Artwork/join2_logo100x88.png Digital Signal Analysis for CsI(T1) Detectors and the Active-Target at R$^3$B

Silva, J.GSI*

2016

Please use a persistent id in citations: urn:nbn:de:hebis:77-diss-1000005377

Abstract: Modern experimental setups tend to replace analogue front-end electronics with fully digital systems.The detector signals are sampled in early stages and most of the signal processing is performeddigitally. The presented work is divided into two major subjects involving digital signalanalysis: firstly employed to correct temperature dependent gain variations and perform particleidentification of CsI(T1) based detectors and secondly to test the functionality of an active-targetprototype (AcTar) for the Reactions with Relativistic Radioactive Beams (R$^3$B) setup.In the first part of this work a pulse shape based method for monitoring the interior temperatureof the CsI(Tl) crystal is proposed. The method uses the correlation between the gain and definedpulse shape parameters to correct the effect of temperature variations in the energy calibration ofthe corresponding detector system. The suitability of the method was tested using both, a photomultipliertube (PMT) and an avalanche photodiode (APD) readout photosensor. The analysisshows that the gain changes due to temperature variations can be corrected to a precision betterthan 1% with both the PMT and APD photosensors, well below the CsI(T1) intrinsic resolution for$\sim$1 MeV $\gamma$-rays. For particle identification, the fuzzy clustering algorithm is used to compute theprinciple pulse shape associated with the different particle species in an unsupervised fashion. Theresults show good discrimination between protons and $\gamma$-rays.In the second part of this work the functionality of the AcTar prototype for the R$^3$B setup has been tested. The objective was to prove the feasibility and performance of such kind of detector withthe use of heavy ion beams. As a proof of concept, a $^{58}$Ni beam at 700 MeV/u was impinging on a He-H$_2$ (3%) gaseous target mixture. The presented results show the principle functionalities of thedetector and suggest that pulse shape analysis can indeed be used to track the recoil particles andreconstruct the kinematics. It is the first time that an active-target of such kind has been successfullytested with beams heavier than carbon.

Note: Dissertation, Johannes Gutenberg-Universität Mainz , 2016

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Contributing Institute(s):

1. Kernreaktionen (KRA)
2. Collaboration FAIR: R3B (R3B@FAIR)

Research Program(s):

1. 613 - Matter and Radiation from the Universe (POF3-613) (POF3-613)

Appears in the scientific report 2016

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