J. L. Schlereth

Neutral K*(890) and ρ0 meson production in e+e- annihilation at ;s=29GeV

Abstract The production of neutral K∗(890) and ρ0 mesons was studied in e+e− annihilation at s =29 GeV using the High Resolution Spectrometer at PEP. Differential cross sections are presented as a function of the scaled energy variable z and compared to π0 and K0 production. The measured multiplicities are 0.84±0.08 ϱ0 mesons and 0.57±0.09 K ∗0 (890) mesons per event for a meson momentum greater than 725 MeV/c. The ratios of vector meson to pseudoscalar meson production for (u,d), s and c quark are compared to predictions of the Lund model.

Charm Quark Production and Fragmentation in

Abstract The electroweak production asymmetry and the decay fragmentation function for e + e − → c c have been measured at s = 29 GeV using charged D ∗ production over the full kinematic range. The data were taken at PEP using the High Resolution Spectrometer. The measured asymmetry is −0.12 ± 0.08. The total production cross section in units of the point cross section corrected for initial state radiation is R D ∗ = 2.7 ± 0.9 .

e^+ e^-

Abstract Using new ν p charged-current data from the Fermilab 15 foot hydrogen bubble chamber, some properties of the ν -induced hadronic jets are studied. The angular size of the jets is measured and compared with results from e + e − annihilation. The jets in the two processes are found to be quite similar in terms of the variables sphericity, thrust, and energy flow.

Annihilation at 29-{GeV}

Event data from proton-proton collisions at the LHC will be selected by the ATLAS experiment in a three level trigger system, which reduces the initial bunch crossing rate of 40 MHz at its first two trigger levels (LVL1+LVL2) to ~3 kHz. At this rate the Event-Builder collects the data from all read-out system PCs (ROSs) and provides fully assembled events to the the event-filter (EF), which is the third level trigger, to achieve a further rate reduction to ~ 200 Hz for permanent storage. The event-builder is based on a farm of O(100) PCs, interconnected via gigabit Ethernet to O(150) ROSs. These PCs run Linux and multi-threaded software applications implemented in C++. All the ROSs and one third of the event-builder PCs are already installed and commissioned. We report on performance tests on this initial system, which show promising results to reach the final data throughput required for the ATLAS experiment.

Comparison of jet size in νp interactions with that in e+e− annihilation

Abstract Using data from the Fermilab 15 ft hydrogen bubble chamber, we have studied inclusive ϱ0 production in antineutrino-proton charged-current interactions. We measure (0.21 ± 0.03) ϱ0/event, corresponding to ϱ0/π−=0.12 ± 0.02. As a function of Q2 and for hadronic masses above a threshold region, the ϱ0/π− ratio shows little variation. At least 50% of the ϱ0s are consistent with coming from the current fragmentation region. The results agree reasonably well with the predictions of the quark fragmentation model of Feynman and field.

Performance of the final Event Builder for the ATLAS Experiment

Abstract The hadronic system produced in charged-current antineutrino interactions is used to study fragmentation of the d-quark. Some problems encountered in defining the current quark fragments are discussed. The properties of the fragmentation function are in good agreement with the expectations of the naive quark-parton model and, in particular, at the present level of statistics we find no need for either a Q 2 -or an x BJ -dependence.

Inclusive ϱ0 production in νp charged-current interactions

Abstract We present data on the reaction ν p → μ + pπ − from an exposure of the Fermilab 15 ft hydrogen bubble chamber. The channel cross section for 5 GeV ν GeV and M( p π − ) GeV is σ = (27 ± 5) × 10 −40 cm 2 . This cross section is dominated by the I = 1 2 production amplitude.

A test of quark fragmentation in the quark-parton model framework

Abstract The reaction e+e− → τ+τ− has been measured using the high resolution spectrometer at PEP. The angular distribution shows a forward-backward asymmetry of −(6.1±2.3±0.5)%, corresponding to an axial-vector coupling if gaτgae = 0.28 ±0.11± 0.03, in good agreement with the standard model of electroweak interactions. The measured cross section yields ifRττ = 1.10± 0.03±0.04, consistent with QED and giving QED cutoff parameters of Λ+>92 GeV and Λ−>246 GeV at 95% C.L.

Study of the reaction νp → μ+pπ−

Abstract We present data on the reaction ν p → μ + pπ − from an exposure of the Fermilab 15 ft hydrogen bubble chamber. The channel cross section for 5 GeV ν GeV and M( p π − ) GeV is σ = (27 ± 5) × 10 −40 cm 2 . This cross section is dominated by the I = 1 2 production amplitude.

Measurement of the reaction e+e− → τ+τ− at √s = 29 GeV

In an effort to reduce data transfer and rate requirements, the Higher Level Trigger of the ATLAS Detector uses Region of Interest (ROI) information forwarded from Level 1 Partitions on a Level 1 Accept. The ROI Builder receives these ROI fragments, which may be considerably skewed in time and may be interspersed with fragments from other events, organizes and formats from these fragments a record for each event accepted by Level 1, selects a processor to manage the event, and transfers via S-link the assembled ROI record to the target processor. The ROI Builder must fulfill these requirements at the Level 1 Trigger rate of 100 kHz while accommodating S-link flow control. A design for the ROI Builder was developed emphasizing parallelism, implemented in FPGAs, and has been run in testbeds at Saclay and CERN.