122648151
Data acquisition and analysis in extremely high data rate experiments
The goal of elementary particle physics is to unravel the properties of matter at the deepest level—that is, to answer questions such as. What are the basic constituents of matter and how do they interact with each other? The search for the answers to such questions has led us to probe the structure of matter at ever‐smaller length scales—from atomic to nuclear and now subnuclear scales. Investigating very small distance scales (below 10−13 cm) has required very high‐energy particles and, consequently, the development of gigantic particle accelerators for producing such particles. (See the box on page 55.) Although these high energy accelerators are marvels of technical and scientific ingenuity, the massive amount of data they produce could not be collected, analyzed and reduced to physics results without another marvel of modern technology: the digital computer!
122620601
Spectroscopy and decays of charm and bottom
After a brief review of the quark model, we discuss our present knowledge of the spectroscopy of charm and bottom mesons and baryons. We go on to review the lifetimes, semileptonic, and purely leptonic decays of these particles. We conclude with a brief discussion B and D mixing and rare decays.
124383108
B Physics at the Tevatron: Now, Soon, and Later
We discuss recent B physics results obtained at the Fermilab Tevatron by CDF, prospects for observing CP violation in the next run, and a proposal for a Dedicated B Collider Experiment, BTeV, at the Tevatron after the next collider run.
116408887
The BTeV trigger and data acquisition system
The BTeV trigger inspects every beam crossing of the Fermilab Tevatron, running at a luminosity of 2 x 10{sup 32}/cm{sup 2}-s, and selects events that have ''detached vertices'' from B decays occurring downstream of the main interaction. The system uses a massively parallel system of FPGAs and microprocessors to produce a trigger decision on average every 396 ns. The trigger calculations are facilitated by the 23 Million channel pixel detector that provides the input to the trigger. Front end electronics sparsifies the remainder of event data and sends it to large, Tbyte, memory buffers that store it until the trigger decision can be made. This complex system presents special challenges in fault monitoring and power and cooling.
119875628
Conference summary: 6th International conference on hyperons, charm, and beauty hadrons (BEACH04)
The 6th International Conference on Hyperons, Charm, and Beauty Hadrons (BEACH04) treated us to a wonderful array of new results. Here the author attempts to summarize the talks and discuss the conference highlights.
123546567
B physics, BTeV, and all that
The status of ''flavor physics'' in our pursuit of knowledge in elementary particle physics is discussed. Then, the BTeV experiment, planned for the Fermilab Tevatron collider, is described briefly and its physics reach is discussed. Comparisons are made to the current B physics experiments at e{sup +}e{sup -} facilities and to the LHCb experiment, planned for the Large Hadron Collider at CERN.
120352655
The ASTERIX spectrometer at LEAR
The ASTERIX spectrometer has been used to study the formation and the ground state of the pp atom and exclusive final states of pp annihilation at rest in a H2 gas target at NTP, using antiprotons from the Low Energy Antiproton Ring (LEAR) at CERN. The article describes the mechanical construction of the apparatus, the trigger logic, the chamber readout, and the data acquisition system. The detector calibration and the offline processing of the 55 million reconstructed events are illustrated. An overview is given about the new physics results obtained by the experiment.
14888027
A precision synchrotron radiation detector using phosphorescent screens
A precision detector to measure synchrotron radiation beam positions is described. It has been designed and installed as part of the beam energy spectrometers at the Stanford Linear Collider (SLC). The distance between pairs of synchrotron radiation beams is measured absolutely to better than 28 mu m on a pulse-to-pulse basis. This contributes less than 5 MeV to the error in measuring SLC beam energies (approximately 50 GeV). A system of high-resolution video cameras viewing precisely aligned fiducial wire arrays overlaying phosphorescent screens has achieved this accuracy. >
173983707
Detecting High Mass H 0 A 0 Pairs at a 1 TeV Linear Collider
This note describes results from a study ofH0A0 associated production at a linear e+e− collider with √ s = 1.0 TeV. For the values of tanβ as well as the H0 and A0 masses considered here, the dominant decay mode is bb pairs. This fully hadronic final state has limited backgrounds at an e+e− collider, but at the LHC or VLHC it suffers extremely high backgrounds from standard QCD jet production. At an e+e− collider, the dominant background is tt production with fully hadronic t–quark decay in which the c–quarks fromW± decay are misidentified as b’s. Other backgrounds such as four–fermion production are negligible because of the signal is dominated by a four b final state. The results of this study are quite encouraging. Good signal–to–background was observed using event rates alone, and reconstructed Higgs mass distributions showed high–efficiency, low background regions. This note has four sections. The first is a description of the Monte Carlo generation and simulation. The second describes the analysis, including mass reconstruction and jet–flavor identification. The third presents the results, and the fourth discusses additional work to be done.
119306140
Tests of a Digital Hadron Calorimeter
In the context of developing a hadron calorimeter with extremely fine granularity for the application of Particle Flow Algorithms to the measurement of jet energies at a future lepton collider, we report on extensive tests of a small scale prototype calorimeter. The calorimeter contained up to 10 layers of Resistive Plate Chambers (RPCs) with 2560 1 \times 1 cm2 readout pads, interleaved with steel absorber plates. The tests included both long-term Cosmic Ray data taking and measurements in particle beams, where the response to broadband muons and to pions and positrons with energies in the range of 1 - 16 GeV was established. Detailed measurements of the chambers efficiency as function of beam intensity have also been performed using 120 GeV protons at varying intensity. The data are compared to simulations based on GEANT4 and to analytical calculations of the rate limitations.
11622855
The lead glass columns: A large shower detector at the SLAC hybrid facility
Abstract A large lead glass shower detector containing 204 lead glass blocks and 250 finger hodoscope elements has been constructed and operated in a photoproduction experiment at the SLAC Hybrid facility. An energy resolution of σ E /E = (0.84+4.8/E 1 2 )% has been achieved for electron energies between 4 and 16 GeV. Details of the apparatus, its stability monitoring system, and its use in triggering the bubble chamber are presented. The performance of the detector in electron identification and π0 reconstruction is discussed.