Rate effects in high-resolution drift chambers

The impact of high counting rates on the spatial resolution of cylindrical drift tubes is investigated in detail and the results are compared with simulations. Electronics effects and space-charge effects are quantitatively analysed. A spatial resolution of $\sigma < 80\,\mu\mathrm{m}$ can be achieved even at rates as high as 1500\,Hz/cm wire length (300\,kHz per wire)

Resolution limits of drift tubes

Measurements of the drift-tube response to charged particle tracks are compared with a complete simulation. The measured resolution of typically 80\,$\mu$m agrees well with the simulation and allows the individual factors limiting the resolution such as diffusion, charge deposit fluctuations, gas gain fluctuations and signal processing to be studied. The results with respect to the dependence of the drift chamber resolution on gas gain, gas pressure and electronics parameters are reported

Front-end electronics for drift tubes in a high-rate environment

A front-end electronics readout for drift tubes in a high-rate environment is presented. This system allows us to encode several pieces of information (leading edge time, trailing edge time, signal charge and piled-up hits from multiple tracks) into a single readout channel that is presented to the TDC. The advantage of active baseline restoration compared to bipolar signal shaping is discussed

Dependence of Drift Tube Performance on the Anode Wire Diameter

Cylindrical pressurized drift tubes with different anode wire diameters wereoperated in a 170~GeV muon test beam. The dependences of spatialresolution, efficiency and streamer probability on the anode wirediameter were measured. The resolution measurements are compared with a simulation

Nov sistem za identifikaciju čestica u području 3 − 8 GeV/c

A threshold imaging Cherenkov (TIC) detector, in conjunction with a tracking device, has been developed to allow pion/kaon, proton identification in the 3–8 GeV/c range of momenta. The most important feature of the system is that it allows spatial identification of the photons of particles above the Cherenkov threshold and their correlation to a particular track. The TIC detector uses a MWPC detector with TMAE for photon conversion into electrons. The first results obtained in ultrarelativistic lead–lead collisions at the CERN SPS accelerator are presented. In a recent development use of a solid CsI cathode instead of TMAE has been successfully tested in proton–lead collisions at the CERN SPS.Razvijen je pozicioni detektor fotona Cerenkovljeva zračenja iznad praga emisije (TIC), koji omogućuje (u sklopu sistema za mjerenje tragova čestica) razlikovanje piona od kaona i protona u području između praga emisije za pione i za kaone t.j između 3 i 8 GeV/c. Najbitnija odlika sistema jest mogućnost dvodimenzijske lokalizacije emitiranih fotona i njihovo jednoznačno pridruživanje određenom tragu čestice koji je odreden drugim detektorima. Detektor TIC primjenjuje višezičane proporcionalne komore s TMAE dodanom brojačkom plinu za konverziju fotona u elektrone. Prikazuju se prvi rezultati dobiveni u ultrarelativističkim sudarima iona olova s metom olova u SPS akceleratoru u CERNu. Nedavno je upotreba čvrstih fotokatoda umjesto TMAE bila uspješno iskušana procesima sudara protona s olovom u SPS akceleratoru

Nov sistem za identifikaciju čestica u području 3 − 8 GeV/c

A threshold imaging Cherenkov (TIC) detector, in conjunction with a tracking device, has been developed to allow pion/kaon, proton identification in the 3–8 GeV/c range of momenta. The most important feature of the system is that it allows spatial identification of the photons of particles above the Cherenkov threshold and their correlation to a particular track. The TIC detector uses a MWPC detector with TMAE for photon conversion into electrons. The first results obtained in ultrarelativistic lead–lead collisions at the CERN SPS accelerator are presented. In a recent development use of a solid CsI cathode instead of TMAE has been successfully tested in proton–lead collisions at the CERN SPS.Razvijen je pozicioni detektor fotona Cerenkovljeva zračenja iznad praga emisije (TIC), koji omogućuje (u sklopu sistema za mjerenje tragova čestica) razlikovanje piona od kaona i protona u području između praga emisije za pione i za kaone t.j između 3 i 8 GeV/c. Najbitnija odlika sistema jest mogućnost dvodimenzijske lokalizacije emitiranih fotona i njihovo jednoznačno pridruživanje određenom tragu čestice koji je odreden drugim detektorima. Detektor TIC primjenjuje višezičane proporcionalne komore s TMAE dodanom brojačkom plinu za konverziju fotona u elektrone. Prikazuju se prvi rezultati dobiveni u ultrarelativističkim sudarima iona olova s metom olova u SPS akceleratoru u CERNu. Nedavno je upotreba čvrstih fotokatoda umjesto TMAE bila uspješno iskušana procesima sudara protona s olovom u SPS akceleratoru

Multiplicity dependence of the pion source in S + A collisions at the CERN SPS

The emission of pions from relativistic heavy-ion collisions of S + S, S + Ag and S + Pb at 200 GeV/nucleon is characterized using two-particle interferometry. The multiplicity dependence of the pion source parameters near mid-rapidity is studied. The transversal and longitudinal source parameters, $R_t$ and $R_l$, show a clear increase with the particle multiplicity. The multiplicity dependence is weaker than that expected from a simple model of a freeze-out at a constant density. % The transversal and longitudinal source parameters $R_t$ and $R_l$, show % a clear increase with the particle multiplicity, consistent with the model % of freeze-out at a constant density

Proton and antiproton distributions at mid-rapidity in proton-nucleus and sulphur-nucleus collisions

Experiment NA44 has measured proton and antiproton distributions at mid-rapidity in sulphur and proton collisions with nuclear targets at 200 and 450 GeV/c per nucleon respectively. The inverse slopes of transverse mass distributions increase with system size for both protons and antiprotons but are slightly lower for antiprotons. this could happen if antiprotons are annihilated in the nuclear medium. The antiproton yield increases with system size and centrality and is largest at mid-rapdity. The proton yield also increases with system size and centrality, but decreases from backward rapidity to midrapidity. The stopping of protons at these energies lies between the full stopping and nuclear transparency scenarios. The data are in reasonable agreement with RQMD predictions except for the antiproton yields from sulphur-nucleus collisions. PACS numbers 25.75.-q 13.85.-t 13.60.R