22 research outputs found
Inclusive Production Cross Sections from 920 GeV Fixed Target Proton-Nucleus Collisions
Inclusive differential cross sections and
for the production of \kzeros, \lambdazero, and
\antilambda particles are measured at HERA in proton-induced reactions on C,
Al, Ti, and W targets. The incident beam energy is 920 GeV, corresponding to
GeV in the proton-nucleon system. The ratios of differential
cross sections \rklpa and \rllpa are measured to be and , respectively, for \xf . No significant dependence upon the
target material is observed. Within errors, the slopes of the transverse
momentum distributions also show no significant
dependence upon the target material. The dependence of the extrapolated total
cross sections on the atomic mass of the target material is
discussed, and the deduced cross sections per nucleon are
compared with results obtained at other energies.Comment: 17 pages, 7 figures, 5 table
The QCD transition temperature: results with physical masses in the continuum limit II.
We extend our previous study [Phys. Lett. B643 (2006) 46] of the cross-over
temperatures (T_c) of QCD. We improve our zero temperature analysis by using
physical quark masses and finer lattices. In addition to the kaon decay
constant used for scale setting we determine four quantities (masses of the
\Omega baryon, K^*(892) and \phi(1020) mesons and the pion decay constant)
which are found to agree with experiment. This implies that --independently of
which of these quantities is used to set the overall scale-- the same results
are obtained within a few percent. At finite temperature we use finer lattices
down to a <= 0.1 fm (N_t=12 and N_t=16 at one point). Our new results confirm
completely our previous findings. We compare the results with those of the
'hotQCD' collaboration.Comment: 19 pages, 8 figures, 3 table
Aufbau und Charakterisierung des schnellen Kontrollsystem fuer das Experiment HERA - B
The experiment HERA-B is currently under construction at the Deutsches Elektronen Synchrotron DESY in Hamburg and, upon completion, will investigate CP-violation in decays of B-mesons. The central challenges for this experiment are a high density of particle tracks in the detector (about 200 tracks per event) and an extremely small signal-to-background-ratio (10"-"1"1 for the decay channel B#->#J/#psi#K_s"0#->#l"+l"-#pi#"+#pi#"-). Data from 540,000 channels must be processed an event rate of 10 MHz and a first level trigger rate of 50 kHz without deadtime. A novel fast control system has been developed to distribute time references, trigger information and test signals to the front end electroncis of all detector components as well as for some first level trigger control functions. This thesis starts with an introduction to the experiment and a detailed description of the data acquisition system which leads to the requirements for the fast control system. The motivation is followed by a description of the fast control hard- and software. The time references and trigger signals, which are distributed by the system, are characterized. Successful synchronization of the detector components is shown by means of data from the 1998 HERA - B -operation. Finally some possibilities the system provides for investigating the first level trigger and potential biases the fast control system might give to HERA - B measurements are discussed. (orig.)SIGLEAvailable from TIB Hannover: RR 8919(1999-016) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman