München 2006 – wissenschaftliches Programm

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HK: Physik der Hadronen und Kerne

HK 20: Instrumentation und Anwendungen

HK 20.5: Vortrag

Dienstag, 21. März 2006, 15:00–15:15, H

Study of time dispersion in scintillators for highly resolved time-of-flight measurements — •Salvador Sanchez Majos, Patrick Achenbach, and Josef Pochodzalla — Inst. für Kernphysik, Universität Mainz, 55099 Mainz

Particle identification (PID) is an essential requirement for the physics research programme of the PANDA experiment at GSI, Darmstadt. The PID of charged hadrons with momenta below 3 − 5 GeV/c is assumed to be performed with the time-of-flight technique (TOF). The best time resolutions presently achieved with large scintillator walls are around 100 − 200 ps. One limitation is the time dispersion due to path length variations of the detected photons. This contribution has been investigated in Monte Carlo studies of light propagation in order to provide strategies for noticeably improving the time resolution of such detectors. It may be achieved by using a photon detector sensitive to the photon’s exit angle.

Our experimental study makes use of two fast photomultipliers (PMTs) and a long rectangular scintillator of dimensions 2000 × 32 × 20 mm³. The scintillator can be excited by means of radioactive sources or a fast pulsed ultraviolet laser in different positions along its longitudinal axis.

Measurements of the signal timing versus photon exit angle have been performed. The experiment successfully demonstrates the principle with a measurable time difference of the order of 400 ps between photons of smaller and those of larger angles detected at different PMT positions.

Work supported by Gesellschaft für Schwerionenforschung F+E project MZ/PO and Forschungsfond 2005, Joh. Gutenberg-Universität Mainz.