Das Lichtpulsersystem des elektromagnetischen CsI(Tl)-Kalorimeters des Babar-Detektors

A light pulser system for the Babar CsI(Tl) calorimeter, capable of monitoring the light yield of the 6580 crystals and of checking the function and linearity of the readout electronics, was developed in a collaboration with groups from Bochum and Edinburgh. The light pulser system is based on the coupling of light from Xenon flashlamps through optical fibers into the individual crystals. The absolute intensity is measured by two special reference systems whose stability is monitored using a radioactive source. During the construction phase the light pulser was used to check the electronics in order to ensure its functioning before the insertion of the calorimeter into the detector where the preamplifier electronics is inaccessable for repair. In monitoring the short term performance of the light pulser system, the stability over one week is better than 0.15 %. Over six months between February and August 2000 the crystal response, as measured by the light pulser, of the three rings of the endcap that are closest to the beam dropped by up to 2 % in comparison with the three outer rings of the endcap, due to radiation damage. Through linearity measurements with the light pulser a flaw in the ADC boards of the calorimeter electronics, which will be fixed in the near future, and cross-talk between channels was found. By a software correction of these effects implemented by members of the collaboration an improvement of the energy resolution of the calorimeter was achieved.

Level thesis:degree_level

thesis.doctoral

Grantor dc:publisher

Technische Universität Dresden

Year

2000

Author dc:creator

• Kocian, Martin Lukas

Contributors dc:contributor

• Spaan, Bernhard
• Schubert, Klaus R.
• Wisniewski, William J.

• Babar
• CsI(Tl)
• Kalorimeter
• Lichtpulser
• Lichtpulsersystem
• calorimeter
• light pulser
• light pulser system