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HK: Fachverband Physik der Hadronen und Kerne

HK 17: Instrumentation IV

HK 17.3: Talk

Tuesday, March 12, 2024, 16:30–16:45, HBR 19: C 2

The Gain Monitoring System for CALIFA — •Carl Georg Boos, Christian Sürder, Thorsten Kröll, Anna-Lena Hartig, Han-Bum Rhee, Leyla Atar, and Fabian Raddatz for the R3B collaboration — Institut für Kernphysik, TU Darmstadt

The CALIFA array is part of the R3B setup used for kinematically complete measurements of nuclear reactions. Those measurements are conducted at GSI and later at FAIR, Darmstadt. CALIFA is one of the core elements, which can be used both as a calorimetre and a spectrometre for the measurement of light charged particles and γ-rays. It consists of CsI(Tl) crystals connected to avalanche photodiodes (APDs). As the gain is not constant for those detector systems, e. g. due to temperature dependencies of the APDs, a pulsed LED gain monitoring system (GMS) was developed. There, light of LEDs is coupled by optical fibres into the detector units mimicking scintillation light. This will provide a stable reference in the energy spectrum of the detector. As the reliability of such a GMS depends strongly on the stability of the light source, the prototypes were investigated in detail.

Different types of shifts of the LED peaks were determined and characterised. Here it was shown that the LEDs themselves are stable, but several factors are responsible for the observed instability. Currently it is worked on the improvement of stability and to investigate the correlation of shifts in different energy ranges.

This work was supported by BMBF 05P19RDFN1 and 05P21RDFN2.

Keywords: R3B; CALIFA; Gain Monitoring System