WITHDRAWN: A scintillator based time-of-flight hodoscope with a new type of emitter follower divider

Design and commissioning of the GSI pion beam

We describe the design of the secondary pion beam-line installed at the SIS 18Tm synchrotron at GSI, Darmstadt, and discuss the commissioning results. The experiments were performed with proton and C-12 primary beams at several energies using beryllium production targets. Pion yields in a momentum range between 0.4 and 2.8 GeV/c were identified, At the highest primary beam energies of 3.5 GeV for proton and 2.0 A GeV for carbon ions, the latter beam produces the highest low-momentum pion yield while at momenta of 1.5 GeV/c the yields are comparable and at 2.8 GeV/c the proton beam is superior. A momentum resolution of around 0.5% is achieved and the time resolution (a) ranges from 100 to 15…

HADES experiment: di-lepton spectroscopy in p + p (2.2 GeV) and C+C (1 and 2 A GeV) collisions

The HADES (High Acceptance Di-Electron Spectrometer) is a tool designed for lepton pair (e+e−) spectroscopy in pion, proton and heavy ion induced reactions in the 1–2AGeV energy range. One of the goals of the HADES experiment is to study in-medium modifications of hadron properties like effective masses, decay widths, electromagnetic form factors etc. Such effects can be probed with vector mesons ( ρ,ω,ɸ ) decaying into e+e− channel. The identification of vector mesons by means of a HADES spectrometer is based on invariant mass reconstruction of e+e− pairs. The combined information from all spectrometer sub-detectors is used to reconstruct the di-lepton signal. The recent results from 2.2Ge…

A scintillator based time-of-flight hodoscope with a new type of emitter follower divider

A high precision, time-of-flight hodoscope has been constructed to analyse the secondary pion beam at GSI, Darmstadt. The hodoscope comprises three scintillator planes with the individual scintillator rods read out by photomultipliers in both ends. A new active base of the emitter follower type has been developed for stabilization of voltages at the last dynodes of the photomultiplier. The time resolution of this system was found to be sigma less than or equal to 150 ps for counting rates up to 2 MHz.