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Backgrounds to the detection of two-body hadronic B decays

Description: We consider backgrounds to the detection of the two-body hadronic decay modes of neutral B mesons and baryons. The largest background is due to the correlated production of pairs of high-p/sub T/ hadrons in the target, but this can be adequately rejected provided the experimental apparatus has sufficient resolution in mass and decay vertex. Another possible source of background arises from the production and decay of charmed and strange particles. Since these particles can travel considerable distances before decaying, they can give rise to backgrounds which may not be rejectable by means of vertex cut. We have simulated several backgrounds from charm, and we find them to be small compared to the expected level of signal. 8 refs., 1 fig., 2 tabs
Date: January 8, 1988
Creator: Kaplan, D.M.; Peng, Jen-Chieh; Abrams, G.S. & Stockdale, I.E.
Partner: UNT Libraries Government Documents Department

Field characterization and personal dosimetry at a high energy ion accelerator

Description: The response of a variety of dosimeters was evaluated in the radiation field outside the shielding of the Lawrence Berkeley Laboratory Bevalac Biomedical Facility. The primary beam was 580 MeV/center dot/A neon ions, incident upon a 30.5-cm polyethylene cube. The field was characterized by a neutron spectrometer consisting of Bonner spheres and other detectors and by estimates of charged particle fluences in NTA film and in the Berklet spectrometer. The responses of American Acrylics CR-39 track-etch plastic detectors and AECL (Canada) type BD-100 Bubble Detectors were compared to those of NTA film, Andersson-Braun remmeter and recombination-chamber results as well as to reference dose equivalents based upon the unfolded neutron spectrum. Evaluations of these dosimeters are discussed. 7 refs., 4 figs.
Date: March 1, 1988
Creator: Greenhouse, N.A.; Busick, D.D.; de Castro, T.M.; Elwyn, A.J.; Hankins, D.E.; Ipe, N.E et al.
Partner: UNT Libraries Government Documents Department

Landau damping in the improved SLC linac: A, The sensitivity to injection jitter

Description: In this report we study the effects of injection jitter on emittance growth, and hence on luminosity, in the improved linac with stronger focusing, and for the new bunch parameters. We consider both cases when Landau damping has been invoked, and when it has not been.
Date: April 1, 1988
Creator: Bane, K.L.F.
Partner: UNT Libraries Government Documents Department

Induction linac drivers for heavy ion fusion

Description: The Heavy Ion Fusion Accelerator Research (HIFAR) program of the USDOE has for several years concentrated on developing linear induction accelerators as Inertial Fusion (IF) drivers. This accelerator technology is suitable for the IF application because it is readily capable of accelerating short, intense pulses of charged particles with good electrical efficiency. The principal technical difficulty is in injecting and transporting the intense pulses while maintaining the necessary beam quality. The approach used has been to design a system of multiple beams so that not all of the charge has to be confined in a single beam line. The beams are finally brought together in a common focus at the target. This paper will briefly present the status and future plans of the program, and will also briefly review systems study results for HIF. 2 refs., 5 figs.
Date: September 1, 1988
Creator: Herrmannsfeldt, W.B. & Keefe, D.
Partner: UNT Libraries Government Documents Department

Introduction to human factors

Description: Some background is given on the field of human factors. The nature of problems with current human/computer interfaces is discussed, some costs are identified, ideal attributes of graceful system interfaces are outlined, and some reasons are indicated why it's not easy to fix the problems. (LEW)
Date: March 1, 1988
Creator: Winters, J.M.
Partner: UNT Libraries Government Documents Department

Recent results on open and hidden charm production in e/sup +/e/sup -/ annihilation at 29 GeV

Description: Inclusive )psi) production in e/sup +/e/sup )minus/) annihilation at 29 GeV has been measured with the Mark II detector. The )psi) cross section is found to be 1.1 )+-) 0.5 )+-) 0.4 pb. An upper limit of 0.02 sigma/sub ..mu mu../ is obtained for other sources of )psi) production. )eta) production has also been investigated, using the ..gamma gamma.. decay mode. The )eta) fragmentation function has been measured and found to be in good agreement with the Lund model prediction. )eta)' production has been measured for the first time in high energy e/sup +/e/sup )minus/) annihilation. A search for D/sub s//sup )+-/) decays into )eta) ..pi../sup )+-/) and )eta)' ..pi../sup )+-/) has been performed and evidence has been found for both decay modes at the 3 sigma level. 11 refs., 5 figs.
Date: March 1, 1988
Creator: Wormser, G.
Partner: UNT Libraries Government Documents Department

Thoughts on software and computing

Description: This talk has three distinct parts. The first two parts are on vector and parallel processing and their success, or lack thereof for HEP. The third part is an analysis on the software situation in HEP. These topics have been chosen because of the frequency with which they are discussed in the hallways of our laboratories and institutions. This review looks at the field from a particular point of view: that of an experimental physicist working with a large detector at a collider and, in addition, only considers the offline processing aspects of the field. 7 refs., 7 figs.
Date: March 1, 1988
Creator: Kunz, P.F.
Partner: UNT Libraries Government Documents Department

Basic optics of the SLC (Stanford Linear Collider) Final Focus System

Description: In this report we discuss some general optics principles and scaling laws that have been useful in guiding the design and operation of the Final Focus System for the Stanford Linear Collider. Included are expressions for the minimum {Beta}{sub x}* and {Beta}{sub y}* that can be expected for the present SLC design at the interaction point as a function of beam emittance. 6 refs., 13 figs.
Date: December 1, 1988
Creator: Brown, K.L.
Partner: UNT Libraries Government Documents Department

Strings in four dimensions

Description: We review the construction and properties of four dimensional string models, using free fermions on the world-sheet. We prove that as opposed to gauge symmetries, broken space-time supersymmetry can only be restored continuously by decompactification. 40 refs.
Date: January 1, 1988
Creator: Bachas, C.P.
Partner: UNT Libraries Government Documents Department

Prospects for physics at e/sup +/e/sup -/ linear colliders

Description: The present thinking on high-energy e/sup /plus//e/sup /minus// linear colliders is reviewed, stressing those points that have consequences for detector design and physics analyses. Detector requirements are discussed. Experimental aspects of the physics that can be done at these colliders are discussed: first the general physics environment, then a standard process, W/sup /plus// W/sup /minus// detection, and finally four examples of the discovery potential of these colliders /emdash/ heavy quarks, heavy leptons, standard Higgs bosons, and charged Higgs bosons. The conclusions of this study will be stated. 23 refs., 40 figs.
Date: March 1, 1988
Creator: Feldman, G.J.
Partner: UNT Libraries Government Documents Department

Report of the experimental areas group

Description: Based on twenty example e/sup +/E/sup /minus// experimental arrangements considered during the PEP summer study, experimental area configurations and requirements are defined. These include: easily movable local shielding to permit close access to operating experiments, adjoining set-up areas for either preparation of upcoming experiments or modification of continuing experiments and the provision of modest power and other utilities. Because many experiments require less than the full length of the designed interaction region (+-10m), it is recommended that initially the free length in half the areas be reduced to +-5m and that efforts be made to increase the luminosity by using low ..beta.. insertions in the beam line. 1 tab.
Date: January 1, 1988
Partner: UNT Libraries Government Documents Department

A status report on the SLD data acquisition system

Description: The basic design of the SLD data acquisition system and its present status are reviewed. Aspects of the design that take particular advantage of the relatively low e/sup +/e/sup /minus// cross section and the low beam crossing rate of a linear collider are explained. 14 refs., 8 figs.
Date: November 1, 1988
Partner: UNT Libraries Government Documents Department

Relativistic klystron research for high gradient accelerators

Description: Relativistic klystrons are being developed as a power source for high gradient accelerator applications which include large linear electron--positron colliders, compact accelerators, and FEL sources. We have attained 200MW peak power at 11.4 GHz from a relativistic klystron, and 140 MV/m longitudinal gradient in a short 11.4 GHz accelerator section. We report here on the design of our first klystrons, the results of our experiments so far, and some of our plans for the near future. 5 refs., 7 figs.
Date: June 1, 1988
Creator: Allen, M.A.; Callin, R.S.; Deruyter, H.; Eppley, K.R.; Fowkes, W.R.; Herrmannsfeldt, W.B. et al.
Partner: UNT Libraries Government Documents Department

Gallium arsenide digital integrated circuits for controlling SLAC CW-RF systems

Description: In order to fill the PEP and SPEAR storage rings with beams from the SLC linac and damping rings, precise control of the linac subharmonic buncher and the damping ring RF is required. Recently several companies have developed resettable GaAs master/slave D-type flip-flops which are capable of operating at frequencies of 3 GHz and higher. Using these digital devices as frequency dividers, one can phase shift the SLAC CW-RF systems to optimize the timing for filling the storage rings. We have evaluated the performance of integrated circuits from two vendors for our particular application. Using microstrip circuit techniques, we have built and operated in the accelerator several chassis to synchronize a reset signal from the storage rings to the SLAC 2.856 GHz RF and to phase shift divide-by-four and divide-by-sixteen frequency dividers to the nearest 350 psec bucket required for filling. 4 refs., 4 figs., 2 tabs.
Date: October 1, 1988
Creator: Ronan, M.T.; Lee, K.L.; Corredoura, P. & Judkins, J.G.
Partner: UNT Libraries Government Documents Department

A FASTBUS-based software trigger for the Mark II detector at the SLC

Description: A new software trigger scheme has been developed to augment and enhance the existing charged and neutral triggers by providing sensitivity to new event topologies and some level of control over accelerator-induced backgrounds. Historically, the Mark II existed with two primary trigger components: a charged track finder based upon the central and vertex drift chambers and the time-of-flight counters; and an electromagnetic trigger based upon the total energy deposited in each of ten calorimeter modules. The trigger component of the new system is based upon the Mark II electromagnetic calorimetry but with significantly increased granularity and the inherent flexibility of software. Trigger processing also benefits from the relatively long period of time (up to 8.3 ms) between SLC beam crossings. The production of long-lived neutral particles provides an example of an event topology which would not have triggered in the old system. By decaying beyond the first few drift chamber layers, such particles avoid the charged particle trigger, yet could produce clear signals in the calorimeters. Another example is the class of events containing a single photon as the visible particle such as occur in the reaction e{sup +}e{sup -} {yields} Z{sup 0}{gamma} {yields} {nu}{nu}{gamma}. Sensitivity to this reaction is necessary to measure the number of neutrino generations. One goal of the new trigger is to achieve nearly 100% efficiency for single photons of energy above 750 MeV. Such a trigger necessarily depends upon a very low and well understood accelerator background for success. A minimum ionizing particle trigger will provide good efficiency for Z{sup 0} {yields} {mu}{mu} or {tau}{tau} at the angles covered by the end cap calorimeters which increases the capabilities for measuring the forward-backward asymmetries. And finally, an improved trigger is more sensitive to complete surprises. 7 refs., 4 figs.
Date: May 1, 1988
Creator: Aleksan, R.; Briggs, D.; Glanzman, T.; Grosse-Wiesmann, P.; Holmgren, S.; Komamiya, S. et al.
Partner: UNT Libraries Government Documents Department

A study of low Q/sup 2/ radiative Bhabha scattering

Description: This thesis presents a study of electron-positron scattering, via nearly real photon exchange, where in the process one or more high energy photons are produced. The motivations behind the work are twofold. Firstly, the study is a sensitive test of the theory of electron-photon interactions, quantum electrodynamics. A deviation from the theory could indicate that the electron is a composite particle. Secondly, a thorough understanding of this process is necessary for experiments to be done in the near future at the Stanford Linear Collider and the LEP facility at CERN. Calculations for the process to third and fourth order in pertubation theory are described. Methods for simulating the process by a Monte Carlo event generator are given. Results from the calculations are compared to data from the Mark II experiment at the PEP storage ring. The ratio of measured to calculated cross sections are 0.993 /+-/ 0.017 /+-/ 0.015 and 0.99 /+-/ 0.16 /+-/ 0.08 for final states with one and two observed photons respectively, where the first errors are statistical and the second systematic. The excellent agreement verifies the calculations of the fourth order radiative correction. No evidence for electron substructure is observed.
Date: March 1, 1988
Creator: Karlen, D.A.
Partner: UNT Libraries Government Documents Department

Canonical description of a second-order achromat

Description: Charged particle motion in second-order magnetic optical achromat is described using a canonical perturbation theory. Necessary and sufficient conditions for the existence of such a device are presented. Given these conditions, the second-order matrix elements at the end of the achromat are found explicity. It is shown that all geometric matrix elements are equal to zero and all chromatic matrix elements are either also equal to zero or proportional to the corresponding chromaticity. Thus all second-order matrix elements vanish simultaneously when the two chromaticities are made to be equal to zero 13 refs., 1 tab.
Date: March 1, 1988
Creator: Kheifets, S.A.; Fieguth, T.H. & Ruth, R.D.
Partner: UNT Libraries Government Documents Department

A CDU-based data acquisition system for the energy spectrometer at the Stanford Linear Collider

Description: We describe a system using the Calorimetry Data Unit (a 32-channel multisample analog integrated circuit) to read out the charge ejected by secondary emission of a synchrotron beam from wires lying in its path. The wires comprise the Wire-Imaging Synchrotron Radiation Detector (WISRD) in the SLC Extraction-Line Spectrometer. The primary module in the system is a board containing 24 channels of charge sensitive amplification, shaping, sampling, multiplexing and digitization. This board also provides a fast analog measure of the charge distribution across the wires. We discuss the design and performance of this system. 4 refs., 5 figs.
Date: October 1, 1988
Creator: Briggs, D.D.; Tinsman, J.E.; Rouse, F. & von Zanthier, C.
Partner: UNT Libraries Government Documents Department

B/sup 0/-anti B/sup 0/ mixing: A theoretical evaluation after ARGUS

Description: After an introduction into the phenomenology of B/sup 0/ -anti B/sup 0/ mixing is given, a rather detailed is presented on the theoretical concepts that are involved. An attempt is made to elucidate the discrepancy between different theoretical claims. CP violtion is touched only very briefly.
Date: January 1, 1988
Creator: Bigi, I.
Partner: UNT Libraries Government Documents Department

Breakdown phenomena in high power klystrons

Description: In the course of developing new high peak power klystrons at SLAC, high electric fields in several regions of these devices have become an important source of vacuum breakdown phenomena. In addition, a renewed interest in breakdown phenomena for nanosecond pulse, multi-megavolt per centimeter fields has been sparked by recent R and D work in the area of gigawatt RF sources. The most important regions of electrical breakdown are in the output cavity gap area, the RF ceramic windows, and the gun ceramic insulator. The details of the observed breakdown in these regions, experiments performed to understand the phenomena and solutions found to alleviate the problems will be discussed. Recently experiments have been performed on a new prototype R and D klystron. Peak electric fields across the output cavity gaps of this klystron exceed 2 MV/cm. The effect of peak field duration (i.e. pulse width) on the onset of breakdown have been measured. The pulse widths varied from tens of nanoseconds to microseconds. Results from these experiments will be presented. The failure of ceramic RF windows due to multipactor and puncturing was an important problem to overcome in order that our high power klystrons would have a useful life expectancy. Consequently many studies and tests were made to understand and alleviate window breakdown phenomena. Some of the results in this area, especially the effects of surface coatings, window materials and processing techniques and their effects on breakdown will be discussed. Another important source of klystron failure in the recent past at SLAC has been the puncturing of the high voltage ceramic insulator in the gun region. A way of alleviating this problem has been found although the actual cause of the puncturing is not yet clear. The ''practical'' solution to this breakdown process will be described and a possible mechanism ...
Date: March 1, 1988
Creator: Vlieks, A.E.; Allen, M.A.; Callin, R.S.; Fowkes, W.R.; Hoyt, E.W.; Lebacqz, J.V. et al.
Partner: UNT Libraries Government Documents Department

Proceedings of the international workshop on next-generation linear colliders

Description: This report contains papers on the next-generation of linear colliders. The particular areas of discussion are: parameters; beam dynamics and wakefields; damping rings and sources; rf power sources; accelerator structures; instrumentation; final focus; and review of beam-beam interaction.
Date: December 1, 1988
Creator: Riordan, M. (ed.)
Partner: UNT Libraries Government Documents Department