3 Matching Results

Search Results

Advanced search parameters have been applied.

Ring-imaging Cerenkov studies. Final performance report

Description: This project involved collaboration in the design, construction and testing of a prototype chamber capable of detecting Cerenkov rings. The chamber incorporated several novel techniques in that it used parallel-plate pad readout and a Cesium-iodide (CsI) solid photocathode. The pad system used gas multiplication where the gas was kept at low pressure to minimize photon losses due to absorption and back-scattering and to minimize ion collection times. Low pressure also lowers the chamber response to charged particles. The chamber gas was ethane at 20 torr and the chamber was operated at room temperature. The chamber was built at the University of Pennsylvania by a University of Puerto Rico graduate student, Jorge Millan. Initial tests at Pennsylvania using a hydrogen-discharge lamp indicated a quantum efficiency of 13% at 190 nm. The chamber was then tested in the M-Test beam line at Fermilab and behind the C3 beamline dump at Brookhaven Lab. Cerenkov rings were clearly observed with each photoelectron typically exciting one pad. On average each ring had five struck pads and only 10% of the events had hits in the center due to the charged particle. These results indicate that a RICH detector using a solid CsI photocathode coupled to a low-pressure, parallel-plate pad chamber is an excellent device for particle identification in high-rate environments when there is a need to cover large areas with minimum expense.
Date: March 13, 1997
Creator: Lopez, A. M.
Partner: UNT Libraries Government Documents Department

Charged-hadron production in e/sup +/e/sup -/ collisions at PEP with the TPC

Description: We have studied hadron production in e/sup +/e/sup -/ annihilation at 29 GeV center of mass energy. We have measured the particle fractions and particle separated differential cross sections using the PEP-4 (Time Projection Chamber) detector. The particles were identified by measuring their ionization energy loss (dE/dx). The pion fraction decreases from above 90% at 400 MeV/c to 55% at 6 GeV/c. Our results for kaon production require that a large number of kaons are produced by strange quarks pulled from the vacuum. We have also measured R, the ratio of the total hadronic cross section to the mu pair cross section. Our value for R is 3.7 with an uncertainty of 10%. This value is in agreement with the results of other experiments and with the predictions of the quark-parton model.
Date: May 13, 1983
Creator: Hadley, N.J.
Partner: UNT Libraries Government Documents Department

Bose-Einstein correlations of pions in e/sup +/e/sup minus/ annihilation at 29 GeV center-of-mass energy

Description: Measurements of two- and three-particle correlations between like-sign pions produced in e/sup +/e/sup minus/ annihilation at 29 GeV center-of-mass energy are presented. The analysis is based on data taken during the period 1982--1986 using the TPC/2..gamma.. detector at PEP. Two-particle correlations are studied as a function of Q, the momentum difference as measured in the rest frame of the pion pair, and as a function of q/sub 0/, the energy difference as measured in the lab frame. The Bose-Einstein enhancement is observed when Q is small even when the energy difference, q/sub 0/, is substantial. This observation provides evidence that the Bose-Einstein correlations are best described by a model that correctly accounts for the relativistic motion of the particle sources. Three-pion correlations are measured both by using a standard three-pion correlation function, and also by using a correlation function for which the correlations between the pairs of pions within the triplet have been subtracted. The observation of three-pion correlations after pair correlations have been subtracted supports the interpretation that the observed correlations are due to Bose-Einstein interference. 56 refs.
Date: January 13, 1989
Creator: Avery, R.E.
Partner: UNT Libraries Government Documents Department