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This dissertation presents the results of the first search for heavy, neutral, longlived particles that decay to photons at a hadron collider. We use a sample of +jet+missing transverse energy events in p¯p collisions at ps = 1.96 TeV taken with the Collider Detector at Fermilab. Candidate events are selected based on the arrival time of a high-energy photon at the electromagnetic calorimeter as measured with a timing system that was recently installed. The final result is that we find 2 events, using 570±34 pb−1 of data collected during 2004-2005 at the Fermilab Tevatron, consistent with the background estimate of 1.3±0.7 events. While our search strategy does not rely on model-specific dynamics, we interpret this result in terms of cross section limits in a supersymmetric model with e01! eG and set a world-best e01 mass reach of 101 GeV/c2 at e = 5 ns. We can exclude any +jet+missing transverse energy signal that would produce more than 5.5 events.

Practically all portable radiation instruments come from the manufacturer with a graph of photon energy response. However, many of these graphs are in log-log format which can disguise relatively large variations in response, particularly for low-energy photons. Additionally, many only include one specific orientation. Thus, in many cases, it is left up to the user to determine for which orientation and photon energies the instrument will be calibrated and ultimately used in the field. It is known that many instruments can have inconsistent responses below ~300 keV, which may lead to under or over-estimation of exposure rate. However, based on relative response plots, one can derive an instrument correction factor that can be applied to the measured exposure rate to yield a constant response curve and more accurately estimate the exposure rate. Using a combination of irradiator systems, six different types of radiation instrumentation were irradiated with photons with energies from 38 to 1253 keV in various orientations. A calibrated ion chamber, in conjunction with an electrometer, was used to determine the conventionally true exposure rates for various x-ray beam codes and radionuclides contained in the irradiator systems. The conventionally true exposure rates were compared to the measured values for each instrument type and relative response plots were constructed. These plots were used to determine an ideal orientation and correction factors were chosen for responses > ±20 percent. From the relative response plots, instrument correction factors are not necessary for the following; Eberline RO-20, Thermo RadEye B20, and Bicron Micro Rem LE. Correction factors of 0.7 and 1.5 should be applied for photons between 80 – 120 keV for the Eberline Teletector 6112B low and high-range detectors, respectively. A correction factor of 0.8 should be applied for photons below 120 keV for the Eberline RO-7-BM. For the Thermo Mk2 EPD, a correction factor of 1.25 should be applied for photons below 40 keV. The primary causes of under and/or over-responses were found to be window attenuation, varying interaction cross-sections, and the range of secondary electrons. Angular dependence and calibrations for specific applications are also discussed.

Reproduction de : Thèse de doctorat : Sciences : Traitement du signal : Toulon : 2007. / Titre provenant du cadre-titre. Bibliographie p.211-212.

Reproduction de : Thèse de doctorat : Physique des particules : Lyon 1 : 2005. / Titre provenant de l'écran titre. 107 réf. bibliogr.

Reproduction de : Thèse de doctorat : Energétique et transferts : Toulouse, INPT : 2006. / Titre provenant de l'écran-titre. Bibliogr. 93 réf.

Cette thèse sera centrée sur les analyses des événements diphotons dans le détecteur ATLAS. L'activité évoluera au cours du temps et couvrira différents aspects: compréhension de la réponse du détecteur, participation a la prise de données, analyse physique et recherche de signaux de physique au-delà du modèle standard.

Copies of three of the author's previously published articles inserted as appendix B. / Includes bibliographical references / 124 leaves : ill ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Thesis (Ph.D.)--University of Adelaide, Dept. of Physics and Mathematical Physics, 1993

Thesis (Ph. D.)--University of Adelaide, Dept. of Physics and Mathematical Physics, 1993. / Copies of three of the author's previously published articles inserted as appendix B. Includes bibliographical references.

Diss. (sammanfattning) Umeå : Umeå universitet, 2006. / Härtill 4 uppsatser.