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Injection Related Background due to the Transverse Feedback

Description: The background in the BaBar detector is especially high during injection, when most components are actually having reduced voltages. The situation is worse for the beam in High Energy Ring (HER) when the LER beam is present. It was found that the transverse feedback system plays an important role when stacking more charge on top of existing bunches. Lowering the feedback gain helped and it was realized later that the best scenario would be to gate off the feedback for only the one bunch, which got additional charge injected into it. The explanation is that the blown-up, but centered, original HER bunch plus the small injected off-axis bunch (each with half the charge) would stay in the ring if not touched, but the feedback system sees half the offset and wants to correct it, therefore disturbing and scraping the blown-up part.
Date: March 18, 2008
Creator: Decker, F.J.; Akre, R.; Fisher, A.; Iverson, R.; Weaver, M. & /SLAC
Partner: UNT Libraries Government Documents Department

Characterization of the PEP-II Colliding-Beam Phase Space by the Boost Method

Description: We present a novel approach to characterize the colliding-beam phase space at the interaction point of the energy-asymmetric PEP-II B-Factory. The method exploits the fact that the transverse-boost distribution of e{sup +}e{sup -} {yields} {mu}{sup +}{mu}{sup -} events reconstructed in the BABAR detector reflects that of the colliding electrons and positrons. The mean boost direction, when combined with the measured orientation of the luminous ellipsoid, determines the e{sup +}-e{sup -} crossing angles. The average angular spread of the transverse boost vector provides an accurate measure of the angular divergence of the incoming high-energy beam, confirming the presence of a sizeable dynamic-{beta} effect. The longitudinal and transverse dependence of the boost angular spread also allow to extract from the continuously-monitored distributions detailed information about the emittances and IP {beta}-functions of both beams during high-luminosity operation.
Date: July 19, 2006
Creator: Weaver, M.; /SLAC; Kozanecki, W.; /DAPNIA, Saclay; Viaud, B. & U., /Montreal
Partner: UNT Libraries Government Documents Department

US Air Force Materiel Command`s second round ECAMP results

Description: The United States Air Force`s Environmental Compliance Assessment and Management Program (ECAMP) is a process to improve Air Force environmental compliance, management, and programmatic support. Midway into the third round of Command-initiated (external) ECAMP evaluations for its fourteen Air Logistics and Systems Centers, the Air Force Material Command (AFMC) is continuing to identify the root causes of instances of environmental noncompliance. The AFMC initiated an analysis of all negative findings identified during the second round of external ECAMP evaluations (June 1991 to January 1993). Presented here is a summary of the analysis with emphasis on trends and root causes.
Date: June 1, 1995
Creator: Levenson, J. B.; Horstman, P. & Weaver, M. A.
Partner: UNT Libraries Government Documents Department

Evaluating the quality and effectiveness of hazardous waste training programs

Description: An installation`s compliance with Resource Conservation and Recovery Act (RCRA) hazardous waste regulations is strongly dependent on the knowledge, skill, and behavior of all individuals involved in the generation and management of hazardous waste. Recognizing this, Headquarters Air Force Materiel Command (HQ/AFMC) determined that an in-depth evaluation of hazardous waste training programs at each AFMC installation was an appropriate element in assessing the overall effectiveness of installation hazardous waste management programs in preventing noncompliant conditions. Consequently, pursuant to its authority under Air Force Instruction (AFI) 32-7042, Solid and Hazardous Waste Compliance (May 12, 1994) to support and maintain hazardous waste training, HQ/AFMC directed Argonne National Laboratory to undertake the Hazardous Waste Training Initiative. This paper summarizes the methodology employed in performing the evaluation and presents the initiative`s salient conclusions.
Date: May 1, 1996
Creator: Kolpa, R.L.; Haffenden, R.A. & Weaver, M.A.
Partner: UNT Libraries Government Documents Department

Expanding the role of internal facility assessments

Description: The US Air Force (USAF) Environmental Compliance Assessment and Management Program (ECAMP) is an effective and comprehensive system to evaluate environmental compliance at individual USAF installations. The ECAMP assessment is typically performed by a team of experts from the installation`s Major Command (MAJCOM) Headquarters, and is often augmented with technical contractor support. As directed by Air Force policy, an external ECAMP assessment is required at a minimum of every three years for each installation. In the intervening years, each installation is required to perform an internal ECAMP assessment, with its own personnel and resources. Even though team composition differs, the internal and external ECAMP assessments are likely to be very similar in scope, objectives, and deliverables. For over nine years, Argonne National Laboratory (ANL) has supported several Air Force MAJCOMs in performing their external ECAMP assessments. More recently, ANL has also had the opportunity to provide technical support and training at individual installations during their preparation and conduct of internal ECAMP assessments. From that experience, the authors have learned that the quality and value of the internal assessment is enhanced by making it a vehicle for training, planning, and interaction among organizations. Various strategies and techniques have been successfully employed to derive maximum benefit and insight from the internal assessment process. Experiences that involve expanding the scope and objectives of internal assessments to meet specific goals are presented. The expansion of scope and objectives include preassessment training, planning, and evaluator interactions as part of the overall internal assessment process.
Date: May 1, 1996
Creator: Kolpa, R.L.; Levenson, J.B. & Weaver, M.A.
Partner: UNT Libraries Government Documents Department

Tritium migration studies at the Nevada Test Site

Description: Emanation of tritium from waste containers is a commonly known phenomenon. Release of tritium from buried waste packages was anticipated; therefore, a research program was developed to study both the rate of tritium release from buried containers and subsequent migration of tritium through soil. Migration of tritium away from low-level radioactive wastes buried in Area 5 of the Nevada Test Site was studied. Four distinct disposal events were investigated. The oldest burial event studied was a 1976 emplacement of 3.5 million curies of tritium in a shallow land burial trench. In another event, 248 thousand curies of tritium was disposed of in an overpack emplaced 6 m below the floor of a low-level waste disposal pit. Measurement of the emanation rate of tritium out of 55 gallon drums to the overpack was studied, and an annual doubling of the emanation rate over a seven year period, ending in 1990, was found. In a third study, upward tritium migration in the soil, resulting in releases in the atmosphere were observed in a greater confinement disposal test. Releases of tritium to the atmosphere were found to be insignificant. The fourth event consisted of burial of 2.2 million curies of tritium in a greater confinement disposal operation. Emanation of tritium from the buried containers has been increasing since disposal, but no significant migration was found four years following backfilling of the disposal hole.
Date: May 1, 1993
Creator: Schulz, R. K. & Weaver, M. O.
Partner: UNT Libraries Government Documents Department

Diagnosing the PEP-II Injection System

Description: The injection of beam into the PEP-II B-Factory, especially into the High Energy Ring (HER) has some challenges. A high background level in the BaBar detector has for a while inhibited us from trickling charge into the HER similar to the Low Energy Ring (LER). Analyzing the injection system has revealed many issues which could be improved. The injection bump between two kickers was not closed, mainly because the phase advance wasn't exactly 180{sup o} and the two kicker strengths were not balanced. Additionally we found reflections which kick the stored beam after the main kick and cause the average luminosity to drop about 3% for a 10 Hz injection rate. The strength of the overall kick is nearly twice as high as the design, indicating a much bigger effective septum thickness. Compared with single beam the background is worse when the HER beam is colliding with the LER beam. This hints that the beam-beam force and the observed vertical blow-up in the HER pushes the beam and especially the injected beam further out to the edge of the dynamic aperture or beyond.
Date: May 9, 2005
Creator: Decker, F.-J.; Donald, M.H.; Iverson, R.H.; Kulikov, A.; Pappas, G.C.; Weaver, M. et al.
Partner: UNT Libraries Government Documents Department

Monitoring of Interaction-Point Parameters Using the 3-Dimensional Luminosity Distribution Measured at PEP-II

Description: The 3-D luminosity distribution at the IP of the SLAC B-Factory is monitored using e{sup +}e{sup -} {yields} e{sup +}e{sup -}, {mu}{sup +}{mu}{sup -} events reconstructed online in the BABAR detector. The transverse centroid and spatial orientation of the luminosity ellipsoid reliably monitor IP orbit drifts. The longitudinal centroid is sensitive to small variations in the average relative RF phase of the beams and provides a detailed measurement of the phase transient along the bunch train. The longitudinal luminosity distribution depends on the e{sup +,-} overlap bunch length and the vertical IP {beta}-functions. Relative variations in horizontal luminous size are detectable at the micron level. In addition to continuous on-line monitoring of all the parameters above, we performed detailed studies of their variation along the bunch train to investigate a temporary luminosity degradation. We also compare {beta}*{sub y} measurements, collected over a year of high-luminosity operation, with HER and LER lattice functions measured by resonant transverse excitation. Our bunch-length measurements are consistent with those obtained by other methods and provide direct evidence for bunch-length modulation.
Date: July 28, 2006
Creator: Viaud, B.F.; U., /Montreal; Kozanecki, W.; /DAPNIA, Saclay; O'Grady, C.; Thompson, J. et al.
Partner: UNT Libraries Government Documents Department

Luminosity Improvement at PEP-II Based on Optics Model and Beam-Beam Simulation

Description: Since the beginning of this year, we have made significant improvements in the machine optics at PEP-II. As a result, the specific luminosity increased nearly 20%. The largest luminosity gain actually came from minimizing nonlinear chromatic effects and running both rings much closer to the half integer resonance in the horizontal plane.
Date: June 21, 2006
Creator: Cai, Y.; Colocho, W.; Diecker, F-J.; Nosochkov, Y.; Raimondi, P.; Seeman, J. et al.
Partner: UNT Libraries Government Documents Department

Combined Phase SpaceCharacterization at the PEP-II IP using Single-beam and Luminous-region Measurements

Description: We present a novel method to characterize the e{sup {+-}} phase space at the IP of the SLAC B-factory, that combines single-beam measurements with a detailed mapping of luminous-region observables. Transverse spot sizes are determined in the two rings with synchrotron-light monitors and extrapolated to the IP using measured lattice functions. The specific luminosity, which is proportional to the inverse product of the overlap IP beam sizes, is continuously monitored using radiative/Bhabha events. The spatial variation of the luminosity and of the transverse-boost distribution of the colliding e{sup {+-}}, are measured using e{sup +}e{sup -} {yields} {mu}{sup +}{mu}{sup -} events reconstructed in the BABAR detector. The combination of these measurements provide constraints on the emittances, horizontal and vertical spot sizes, angular divergences and {beta} functions of both beams at the IP during physics data-taking. Preliminary results of this combined spot-size analysis are confronted with independent measurements of IP {beta}-functions and overlap IP beam sizes at low beam current.
Date: June 23, 2006
Creator: Bevan, A.; /Queen Mary, U. of London; Kozanecki, W.; /Saclay; Viaud, B.; U., /Montreal et al.
Partner: UNT Libraries Government Documents Department

Trickle-Charge: a New Operational Mode for PEP-II

Description: In regular top-up-and-coast operation, PEP-II average luminosity is about 70-75% of the peak luminosity due to detector ramp-down and ramp-up times plus the time it takes to top-up both beams. We recently commissioned a new operational mode where the Low Energy Ring is injected continuously without ramping down the detector. The benefits--increased luminosity lifetime and roughly half the number of top-ups per shift--were expected to give an increase in delivered luminosity of about 15% at the same peak luminosity; this was confirmed in test runs. In routine trickle operation, however, it appears that the increase in delivered luminosity is more than twice that due to an increase in availability credited to the more stable operating conditions during trickle operation. Further gains were made when continuous injection was extended to the high energy ring as well. In this paper we will present our operational experience as well as some of the diagnostics we use to monitor and maintain tuning of the machine in order to control injection background and protect the detector.
Date: May 9, 2005
Creator: Kozanecki, W.; Colocho, W. S.; Decker, F. -J.; Ecklund, S.; Fisher, A. S.; Iverson, R. H. et al.
Partner: UNT Libraries Government Documents Department

Measurements of B meson decays to (omega)K* and (omega)(rho)

Description: The authors describe searches for B meson decays to the charmless vector-vector final states {omega}K* and {omega}{rho} in 89 million B{bar B} pairs produced in e{sup +}e{sup -} annihilation at {radical}s = 10.58 GeV.
Date: March 14, 2006
Creator: Aubert, B.; Cheng, C. H.; Lange, D. J.; Simani, M. C.; Wright, D. M.; Abrams, G. S. et al.
Partner: UNT Libraries Government Documents Department