118172758
Triggering at Isabelle; the first 200 nanoseconds
At full luminosity of ISABELLE and with an anticipated pp total cross section of 60 mb, there will be, on the average, one interaction every 70 ns. At the other end of the spectrum, it will probably take about 10 ms to store a complete event onto magnetic tape. In between these two extremes comes a triggering scheme which must select the one event out of 14,285,714 that is of interest to the experimenter. In a typical experiment, a certain small number of signals will come into an electronics trailer on cables that are as short as possible and have propagation velocities as high as possible. With these signals a fast decision will be made as to whether the rest of the information coming in on the slower, longer cables should be further processed or not. The typical length of time for this decision is 200 ns. Some of the problems arising during that first 200 ns are considered, and some examples of attempts to solve those problems are given.
123273188
COMPARISON OF HIGH TRANSVERSE MOMENTUM PI0 PRODUCTION FROM PI-, K-, P, AND ANTI-P BEAMS.
We compare high-transverse-momentum (P/sub perpendicular/) inclusive ..pi../sup 0/ production from ..pi../sup -/, K/sup -/, p, and p beams, at 100 and 200 GeV/c, for center-of-mass (c.m.) angles ranging from 2/sup 0/ to 115/sup 0/, and P/sub perpendicular/ .. ..pi../sup 0/X)/sigma (..pi..p ..-->.. ..pi../sup 0/X) decreases with increasing P/sub perpendicular/, and changes dramatically with c.m. angle. Also, the ratios sigma (K/sup -/p ..-->.. ..pi../sup 0/X)/sigma (..pi../sup -/p ..-->.. ..pi../sup 0/X) and sigma (pp ..-->.. ..pi../sup 0/X)/sigma (pp ..-->.. /sup 0/X) are approximately constant. The measurements are consistent with a theoretical viewpoint in which constituents of the incident hadrons undergo a hard-scattering subprocess.
122426348
Pion Charge Exchange Scattering at High-Energies
We report on a study of pion charge-exchange scattering carried out at Fermilab in the energy range 20 to 200 GeV. The results can be described remarkably well by a simple Regge-pole model. The charge-exchange cross sections in the forward direction lead to a prediction for the difference in total cross sections of ..pi../sup -/p and ..pi../sup +/p which is in satisfactory agreement with direct measurements of this difference in another experiment at Fermilab. (AIP)
118861611
Observation of inclusive. omega. production at large transverse momentum
We have observed the production of ..omega.. mesons at large transverse momentum produced in 200-GeV/c pBe interactions. The ratio of inclusive production of ..omega.. to ..pi../sup 0/ at transverse momenta above 2.2 GeV/c is 0.44 +- 0.08 near x=0. The upper limit for eta' to eta production is <1.4 in the same kinematic region.
115852024
Measurement of the quantum efficiency of TMAE and TEA from threshold to 120 nm
Several existing and planned high energy physics experiments incorporate detectors which use either TMAE (tetrakis-dimethylaminoethylene) or TEA (triethylamine) as their photosensitive agent. Understanding the operation of these devices requires knowledge of the absolute photoionization quantum efficiencies and absorption lengths of TMAE and TEA. In an experiment performed at the National Synchrotron Light source at Brookhaven National Laboratory, we have measured these parameters from 120 nm to 280 nm. The quantum efficiencies were normalized to the known photoionization yields of benzene and cis-2-butene. The results of these measurements and details of the experiment are presented in this paper.
120421514
GAS SYSTEM FOR ALEPH TPC
Abstract Operation of the time projection chamber of the ALEPH experiment at LEP requires a high-purity argon/methane gas mixture supplied to the detector under stable conditions to ensure minimum signal attenuation throughout the 43 m 3 detector volume (max. 2.2 m drift length) and maintain near-constant electron drift velocity in the gas over extended periods of time. Design considerations for a gas system to fulfil these conditions are presented and details given of the construction, operational aspects and of the achieved performance.
56365630
Recent Results from the Fermi Gamma-ray Space Telescope
The Fermi Gamma-ray Space Telescope, formerly named GLAST, is a mission in low-Earth orbit to observe gamma rays from the cosmos in the broad energy range from 20 MeV to >300 GeV, with supporting observations of gamma-ray bursts from 8 keV to 30 MeV. The telescope far surpasses previous generations in its ability to detect and localize faint gamma-ray sources, as well as its ability to see 20% of the sky at any instant and scan the entire sky on a timescale of a few hours. With its launch on 11 June 2008, Fermi opened a new and exciting window on a wide variety of exotic astrophysical objects and is enabling new research on such topics as the origin and circulation of cosmic rays and searches for hypothetical new phenomena such as annihilation of dark matter. In addition to introducing the mission and the instruments, this talk will present the latest results on dark matter searches, diffuse gamma-ray production, galactic sources such as pulsars and micro-quasars, and extragalactic sources such as active galaxies and gamma-ray bursts.
20578469
A Generic Surface Sampler for Monte Carlo Simulations
We present a Monte Carlo algorithm that generates points randomly and uniformly on a set of arbitrary surfaces. The algorithm is completely general and only requires the geometry modeling software to provide the intersection points of an arbitrary line with the surface being sampled. We demonstrate the algorithm using the Geant4 Monte Carlo simulation toolkit. The efficiency of the sampling algorithm is discussed, along with various options in the implementation and example applications.
15400380
Fabrication of the GLAST Silicon Tracker Readout Electronics
A unique electronics system has been built and tested for reading signals from the silicon-strip detectors of the Gamma-ray Large Area Space Telescope mission. The system amplifies and processes signals from 884 736 36-cm long silicon strips in a 4times4 array of tower modules. An aggressive mechanical design fits the readout electronics in narrow spaces between the tower modules, to minimize dead area. This design and the resulting departures from conventional electronics packaging led to several fabrication challenges and lessons learned. This paper describes the fabrication processes and how the problems peculiar to this design were overcome
2889124
The silicon tracker/converter for the gamma-ray large area space telescope
The Silicon Tracker/Converter of the Gamma-ray Large Area Space Telescope (GLAST) will have an active area of 80 m2, representing one of the largest planned applications of the silicon-strip detector technology. The large number of channels (1.3 million) to read out, together with the requirement that the tracker provide the trigger to the data acquisition, force the readout electronics to be of very low noise. Furthermore, to "t into the power constraints of the satellite environment, the electronics must have an ultra-low power consumption. To ful"ll these requirements, plus others imposed by the space environment, such as redundancy, a mixed mode CMOS front-end readout chip and a digital readout controller chip have been designed and prototyped. In this article, we present the status of the readout electronics and the results from a test-beam study with a small GLAST tracker prototype. ( 1999 Elsevier Science B.V. All rights reserved.