449 Matching Results

Search Results

Advanced search parameters have been applied.

Soft inflation

Description: We study the cosmology resulting from two coupled scalar fields, one which is either a new inflation or chaotic type inflation and the other which has an exponentially decaying potential. Such potential may appear in the conformally transformed frame of generalized Einstien theories like the Jordan-Brans-Dicke theory. The constraints necessary for successful inflation are examined. We find conventional GUT models such as SU(5) are compatible with new inflation, while restrictions on the self-coupling constant are significantly loosened for chaotic inflation. 20 refs., 1 fig.
Date: April 1, 1990
Creator: Berkin, A.L. (Waseda Univ., Tokyo (Japan). Dept. of Physics); Maeda, Kei-ichi (Waseda Univ., Tokyo (Japan). Dept. of Physics Fermi National Accelerator Lab., Batavia, IL (USA)) & Yokoyama, Jun'ichi (Tokyo Univ. (Japan). Dept. of Physics Fermi National Accelerator Lab., Batavia, IL (USA))
Partner: UNT Libraries Government Documents Department

Gravitational effects of global textures

Description: A solution for the dynamics of global textures is obtained. Their gravitational field during the collapse and the subsequent evolution is found to be given solely by a space-time dependent deficit solid angle.'' The frequency shift of photons traversing this gravitational field is calculated. The space-time dependent texture metric locally contracts the volume of three-space and thereby induces overdensities in homogeneous matter distributions. There are no gravitational forces unless matter has a nonzero angular momentum with respect to the texture origin which would be the case for moving textures.
Date: March 1, 1990
Creator: Noetzold, D. (Chicago Univ., IL (USA). Astronomy and Astrophysics Center Fermi National Accelerator Lab., Batavia, IL (USA))
Partner: UNT Libraries Government Documents Department

Ultrahigh-energy particle flux from cosmic strings

Description: We estimate the expected flux of ultrahigh-energy (> 10{sup 18}eV) protons in the present epoch due to a process which involves collapse or multiple self-intersections of a special class of closed cosmic string loops in the universe. We compare this flux with the observed flux of ultrahigh-energy cosmic rays, and discuss the implications. 19 refs., 1 fig.
Date: April 1, 1990
Creator: Bhattacharjee, P. (Chicago Univ., IL (USA). Enrico Fermi Inst. Fermi National Accelerator Lab., Batavia, IL (USA))
Partner: UNT Libraries Government Documents Department

Stability of compactification during inflation

Description: The possibility that inflation may trigger an instability in compactification of extra spatial dimensions is considered. In old, new, or extended inflation, the false vacuum energy results in a semiclassical instability in which the scalar field representing the radius of the extra dimensions may tunnel through a potential barrier leading to an expansion of the internal space. In chaotic inflation, if the initial value of the scalar field responsible for inflation is large enough, the internal space becomes classically unstable to ever increasing expansion. Restrictions on inflationary models necessary to keep the extra dimensions small are discussed. 15 refs., 5 figs.
Date: March 1, 1990
Creator: Amendola, L.; Litterio, M.; Occhionero, F. (Osservatorio Astronomico, Rome (Italy)) & Kolb, E.W. (Osservatorio Astronomico, Rome (Italy) Fermi National Accelerator Lab., Batavia, IL (USA) Chicago Univ., IL (USA))
Partner: UNT Libraries Government Documents Department

Gravitational couplings of the inflaton in extended inflation

Description: We discuss a new extended inflationary scenario evading the difficulties of the original model. Our model can thermalize the energy in the bubble walls by the necessary epoch, and establish a Robertson-Walker frame in the bubble clusters. The essential new ingredient in our model is the observation that the coupling of inflaton to the Jordan-Brans-Dicke field is expected to be different from that of visible matter. 13 refs., 1 fig.
Date: February 1, 1990
Creator: Holman, R.; Wang, Yun (Carnegie-Mellon Univ., Pittsburgh, PA (USA). Dept. of Physics) & Kolb, E.W. (Fermi National Accelerator Lab., Batavia, IL (USA) Chicago Univ., IL (USA))
Partner: UNT Libraries Government Documents Department

Measurement of the xenon/deuterium inelastic cross section ratio using 490 GeV/c muons

Description: Inelastic scattering of 490 GeV {mu}{sup +} from deuterium and xenon nuclei has been studied at energy transfers (v) up to 370 GeV and four-momentum transferred squared (Q{sup 2}) down to 0.1 GeV{sup 2}. A depletion in the inelastic {mu}{sup +} cross section has been observed from xenon compared to deuterium in the kinematic range 0.001 < x{sub Bj} < 0.08. The ratio of the xenon/deuterium cross section decreases with increasing v but does not depend on Q{sup 2}. The data extend the v and Q{sup 2} ranges studied previously in charged lepton and photoproduction experiments. The data agree qualitatively with models that invoke parton fusion in nuclei and models based on generalized vector dominance.
Date: November 1, 1990
Creator: Halliwell, C. (Illinois Univ., Chicago, IL (USA))
Partner: UNT Libraries Government Documents Department

The ACP (Advanced Computer Program) multiprocessor system at Fermilab

Description: The Advanced Computer Program at Fermilab has developed a multiprocessor system which is easy to use and uniquely cost effective for many high energy physics problems. The system is based on single board computers which cost under $2000 each to build including 2 Mbytes of on board memory. These standard VME modules each run experiment reconstruction code in Fortran at speeds approaching that of a VAX 11/780. Two versions have been developed: one uses Motorola's 68020 32 bit microprocessor, the other runs with AT and T's 32100. both include the corresponding floating point coprocessor chip. The first system, when fully configured, uses 70 each of the two types of processors. A 53 processor system has been operated for several months with essentially no down time by computer operators in the Fermilab Computer Center, performing at nearly the capacity of 6 CDC Cyber 175 mainframe computers. The VME crates in which the processing ''nodes'' sit are connected via a high speed ''Branch Bus'' to one or more MicroVAX computers which act as hosts handling system resource management and all I/O in offline applications. An interface from Fastbus to the Branch Bus has been developed for online use which has been tested error free at 20 Mbytes/sec for 48 hours. ACP hardware modules are now available commercially. A major package of software, including a simulator that runs on any VAX, has been developed. It allows easy migration of existing programs to this multiprocessor environment. This paper describes the ACP Multiprocessor System and early experience with it at Fermilab and elsewhere.
Date: September 1, 1986
Creator: Nash, T.; Areti, H.; Atac, R.; Biel, J.; Case, G.; Cook, A. et al.
Partner: UNT Libraries Government Documents Department

The Fermilab PBAR-P Collider: Present status and future plans

Description: The Tevatron Collider is performing beyond expectations for its first physics run. The peak luminosity is already 1.6 times the design goal of 10/sup 30/ cm/sup /minus/2/ s/sup /minus/1/. The anticipated integrated luminosity recorded by the major detector, CDF, is 3 inverse picobarns which should be sufficient to see the top quark if its mass is less than 110 GeV. The next two Collider runs will have improved performance with luminosity approaching 10/sup 31/ at two interaction regions. In the years between 1993 and 2000, the Collider energy will be increased by using the highest field superconducting magnets then available, where 8.8 T would give 2 TeV on 2 TeV pbar-p collisions with a luminosity above 10/sup 31/. To facilitate this possibility and to improve the general Collider capabilities, a new 150 GeV Main Injector is now being designed. 3 figs., 2 tabs.
Date: November 1, 1988
Creator: Johnson, R.
Partner: UNT Libraries Government Documents Department

Feasibility of short-lived radionuclide production at Fermilab

Description: The feasibility of establishing a facility for short-lived radionuclide production hinges on the availability of the Fermilab injector linac and on how such a program would fit in with the primary mission of the laboratory. The linac is available 168 hours per week except for scheduled maintenance, which typically does not exceed one to two shifts per week, and HEP requirements. The laboratory may be reluctant to make a commitment for the routine production of SLRs however, due to its understanding of the requirements for reliable scheduled delivery of targets. But, the laboratory is also quite interested in establishing industrial liaisons. It would be willing to explore feasible industrial proposals, especially with regards to developing a research-type facility where the technology and methods developed at Fermilab could be utilized elsewhere.
Date: April 29, 1982
Creator: Ten Haken, R.K.; Awschalom, M. & Rosenberg, I.
Partner: UNT Libraries Government Documents Department

Explanation of persistent high frequency density structure in coalesced bunches

Description: It has been observed that after the Main Ring rf manipulation of coalescing (where 5 to 13 primary bunches are transferred into a single rf bucket) the new secondary bunch displays evidence of high frequency density structure superimposed on the approximately Gaussian longitudinal bunch length distribution. This structure is persistent over a period of many seconds (hundreds of synchrotron oscillation periods). With the help of multiparticle simulation programs, an explanation of this phenomenon is given in terms of single particle longitudinal phase space dynamics. No coherent effects need be taken into account. 6 refs., 10 figs.
Date: July 1, 1988
Creator: Jackson, Gerald P.
Partner: UNT Libraries Government Documents Department

High performance parallel computers for science: New developments at the Fermilab advanced computer program

Description: Fermilab's Advanced Computer Program (ACP) has been developing highly cost effective, yet practical, parallel computers for high energy physics since 1984. The ACP's latest developments are proceeding in two directions. A Second Generation ACP Multiprocessor System for experiments will include $3500 RISC processors each with performance over 15 VAX MIPS. To support such high performance, the new system allows parallel I/O, parallel interprocess communication, and parallel host processes. The ACP Multi-Array Processor, has been developed for theoretical physics. Each $4000 node is a FORTRAN or C programmable pipelined 20 MFlops (peak), 10 MByte single board computer. These are plugged into a 16 port crossbar switch crate which handles both inter and intra crate communication. The crates are connected in a hypercube. Site oriented applications like lattice gauge theory are supported by system software called CANOPY, which makes the hardware virtually transparent to users. A 256 node, 5 GFlop, system is under construction. 10 refs., 7 figs.
Date: August 1, 1988
Creator: Nash, T.; Areti, H.; Atac, R.; Biel, J.; Cook, A.; Deppe, J. et al.
Partner: UNT Libraries Government Documents Department

First order formalism for quantum gravity

Description: We develop a first order formalism for the quantization of gravity. We take as canonical variables both the induced metric and the extrinsic curvature of the (d - 1) -dimensional hypersurfaces obtained by the foliation of the d - dimensional spacetime. After solving the constraint algebra we use the Dirac formalism to quantize the theory and obtain a new representation for the Wheeler-DeWitt equation, defined in the functional space of the extrinsic curvature. We also show how to obtain several different representations of the Wheeler-DeWitt equation by considering actions differing by a total divergence. In particular, the intrinsic and extrinsic time approaches appear in a natural way, as do equivalent representations obtained by functional Fourier transforms of appropriate variables. We conclude with some remarks about the construction of the Hilbert space within the first order formalism. 10 refs.
Date: May 1, 1987
Creator: Gleiser, M.; Holman, R. & Neto, N.P.
Partner: UNT Libraries Government Documents Department

Helium-to-neon modification for a DuPont 120SSA or 24-120 leak detector

Description: When helium leak detecting is hindered by a system or atmosphere saturated with helium, leak checking can be continued by modifying the DuPont 120SSA/24-120 Mass Spectrometer Leak Detector to detect neon. Although DuPont markets a three gas leak detector (helium, neon and argon), the DuPont 120SSA/24-120 is convertible to neon by simply changing the magnet and retuning for neon peak. The sensitivity is 2 x 10/sup -9/ Atm/cc/sec/division neon. If an increase in sensitivity is desired, throttle diffusion pump with valve or install choke. Modification procedures and tuning procedures are described. (WHK)
Date: August 26, 1982
Creator: Juravic, F.
Partner: UNT Libraries Government Documents Department

Dimuon production in hadronic interactions

Description: This report summarizes the new data submitted to the XXI International Conference on High Energy Physics on high mass dimuon production in ..pi../sup -/N and anti pN interactions by Fermilab Experiment E-537, CERN Experiment NA3 and Fermilab Experiment E-326. Successes and failures of the Drell-Yan model and low order QCD are reviewed. New results on the production of the J/psi from E-537, NA3 and CERN experiment WAll are also reported.
Date: October 1, 1982
Creator: Cox, B.
Partner: UNT Libraries Government Documents Department

Gas-mixing system for drift chambers using solenoid valves

Description: We describe an inexpensive system for mixing argon and ethane drift chamber gas which is used for the E-605 experiment at Fermilab. This system is based on the idea of intermittent mixing of gases with fixed mixing flow rates. A dual-action pressure switch senses the pressure in a mixed gas reservoir tank and operates solenoid valves to control mixing action and regulate reservoir pressure. This system has the advantages that simple controls accurately regulate the mixing ratio and that the mixing ratio is nearly flow rate independent. We also report the results of the gas analysis of various samplings, and the reliability of the system in long-term running.
Date: April 1, 1983
Creator: Cooper, W.E.; Sugano, K. & Trentlage, D.B.
Partner: UNT Libraries Government Documents Department

Flying wires at Fermilab

Description: Transverse beam profile measurement systems called ''Flying Wires'' have been installed and made operational in the Fermilab Main Ring and Tevatron accelerators. These devices are used routinely to measure the emittance of both protons and antiprotons throughout the fill process, and for emittance growth measurements during stores. In the Tevatron, the individual transverse profiles of six proton and six antiproton bunches are obtained simultaneously, with a single pass of the wire through the beam. Essential features of the hardware, software, and system operation are explained in the rest of the paper. 3 refs., 4 figs.
Date: March 1, 1989
Creator: Gannon, J.; Crawford, C.; Finley, D.; Flora, R.; Groves, T. & MacPherson, M.
Partner: UNT Libraries Government Documents Department

A floating point engine for lattice gauge calculations

Description: The latest in low cost computing solutions from the Fermilab Advanced Computer Program is targeted at Lattice Gauge theory calculations and delivers supercomputer performance at a fraction of the cost. A typical system with 256 processors, 2.5 Gigabytes of memory, and 64 Gigabytes of on-line tape storage, delivers a peak performance of 5 billion floating point operations per second. The programming environment, Canopy, provides a comprehensive, hardware independent, distributed processing platform from within the more familiar environments of FORTRAN, C, and UNIX. This paper describes the individual processing elements of the system and gives a brief description of the Canopy software. 8 refs., 3 figs.
Date: November 1, 1988
Creator: Husby, D.; Atac, R.; Cook, A.; Deppe, J.; Fischler, M.; Gaines, I. et al.
Partner: UNT Libraries Government Documents Department

Experimental results on heavy flavour hadro- and photo-production

Description: Results from experiments on the production of beauty and charm with hadron and photon beams are reviewed. Beauty production experiments are beginning to obtain b anti b cross-sections with hadron beams. Hadroproduction of charm is a somewhat more mature field, although high statistics are still eagerly sought. The situation is most promising with charm photoproduction experiments where total cross-sections, p/sub T//sup 2/ and X/sub F/ distributions and other production characteristics are now known in considerable detail.
Date: May 1, 1987
Creator: Purohit, M.V.
Partner: UNT Libraries Government Documents Department

An eye for accuracy: Coordinate measuring in an R and D environment

Description: The Fermi National Accelerator Laboratory (Fermilab) is a high energy physics research facility. Its purpose is to explore the basic composition of matter. Fermilab does not produce a product nor does it produce electrical power. Funded by the Department of Energy, the main tool for its study is the Tevatron, the world's first superconducting particle accelerator. Fermilab fabricates and assembles the majority of magnets and other components for the accelerator rings of the atom smasher. The magnet is the key to accelerating subatomic particle (i.e., protons, anti-protons, etc.) which the particle accelerator uses to collide into other beams or fixed targets. The production of a magnet assembly requires stacking steel laminations precisely the proper size and shape necessary to create the required magnetic field. In this paper, it will be discussed how coordinate measuring is accomplished at Fermilab, and how such things as tight budgets, and lack of product line can lead to some interesting and useful techniques. 6 figs.
Date: June 1, 1988
Creator: Kobliska, G.R.
Partner: UNT Libraries Government Documents Department

Expanded Fermilab pressure vessel directory program

Description: Several procedures have been written to manage the information pertaining to the vacuum tanks and pressure vessels for which the laboratory is responsible. These procedures have been named TANK1 for the vessels belonging to the Accelerator Division, TANK2 and TANK3 for the vessels belonging to the Research Division and to Technical Support respectively, and TANK4 for the vessels belonging to the Business Division. The operating procedures are otherwise identical in every respect.
Date: January 1, 1983
Creator: Tanner, A.
Partner: UNT Libraries Government Documents Department

The Fermilab upgrade

Description: This paper discusses the upgrades needed at Fermilab Tevatron facility to meet the future physics needs. Historical aspects are also discussed. 3 figs.
Date: September 25, 1988
Creator: Lederman, L.M.
Partner: UNT Libraries Government Documents Department

Fermilab Central Computing Facility: Energy conservation report and mechanical systems design optimization and cost analysis study

Description: This report is developed as part of the Fermilab Central Computing Facility Project Title II Design Documentation Update under the provisions of DOE Document 6430.1, Chapter XIII-21, Section 14, paragraph a. As such, it concentrates primarily on HVAC mechanical systems design optimization and cost analysis and should be considered as a supplement to the Title I Design Report date March 1986 wherein energy related issues are discussed pertaining to building envelope and orientation as well as electrical systems design.
Date: November 12, 1986
Creator: Krstulovich, S.F.
Partner: UNT Libraries Government Documents Department

Design, implementation, and operation of a class based batch queue scheduler for VAX/VMS

Description: Fermilab found that the standard VMS batch configuration options were inadequate for the job mix that exists on the Fermilab central computer facility VAX cluster. Accordingly, Fermilab designed and implemented a class based batch queue scheduler. This scheduler makes use of the standard VMS job controller and batch system. Users interact with the scheduler at job submission time by specification of CPU time limits and batch job characteristics. This scheduler allows Fermilab to make efficient use of our large heterogeneous VAX cluster which contains machines ranging from a VAX 780 to a VAX 8800. The scheduler was implemented using the VMS system services $GETQUI and $SNDJBC, without changes to the existing VMS job scheduler. As a result, the scheduler should remain compatible with future VMS versions. This session will discuss the design goals, implementation, and operational experience with Fermilab's class based batch queue scheduler.
Date: May 20, 1988
Creator: Chadwick, K.
Partner: UNT Libraries Government Documents Department

Computing possibilities in the mid 1990s

Description: This paper describes the kind of computing resources it may be possible to make available for experiments in high energy physics in the mid and late 1990s. We outline some of the work going on today, particularly at Fermilab's Advanced Computer Program, that projects to the future. We attempt to define areas in which coordinated R and D efforts should prove fruitful to provide for on and off-line computing in the SSC era. Because of extraordinary components anticipated from industry, we can be optimistic even to the level of predicting million VAX equivalent on-line multiprocessor/data acquisition systems for SSC detectors. Managing this scale of computing will require a new approach to large hardware and software systems. 15 refs., 6 figs.
Date: September 1, 1988
Creator: Nash, T.
Partner: UNT Libraries Government Documents Department