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Inflation in spherically symmetric inhomogeneous models

Description: Exact analytical solutions of Einstein's equations are found for a spherically symmetric inhomogeneous metric in the presence of a massless scalar field with a flat potential. The process of isotropization and homogenization is studied in detail. It is found that the time dependence of the metric becomes de Sitter for large times. Two cases are studied. The first deals with a homogeneous scalar field, while the second with a spherically symmetric inhomogeneous scalar field. In the former case the metric is of the Robertson-Walker form, while the latter is intrinsically inhomogeneous. 16 refs.
Date: November 1, 1986
Creator: Stein-Schabes, J.A.
Partner: UNT Libraries Government Documents Department

Application of NMR circuit for superconducting magnet using signal averaging

Description: An NMR circuit was used to measure the absolute field values of Fermilab Energy Doubler magnets up to 44 kG. A signal averaging method to improve the S/N ratio was implemented by means of a Tektronix Digital Processing Oscilloscope, followed by the development of an inexpensive microprocessor based system contained in a NIM module. Some of the data obtained from measuring two superconducting dipole magnets are presented.
Date: January 1, 1977
Creator: Yamada, R.; Ishimoto, H.; Shea, M. F.; Schmidt, E. E. & Borer, K.
Partner: UNT Libraries Government Documents Department

Design and performance characteristics of the E769 beamline transition radiation detector

Description: A Transition Radiation Detector (TRD) was designed and built for E769, a Fermilab Fixed Target experiment, for use in separating pions form protons or kaons in a 250 GeV/c positive beam at the Tagged Photon Laboratory (TPL). Requirements placed on the detector were that it operate in a high rate (approx.2 MHz) environment and that it be relatively easy to build since it had to be ready approximately one year from the date of its inception. The short time available precluded exposing prototypes to a test beam making it necessary to rely on source testing and Monte Carlo programs to predict the detector performance. When operated in the beam, the detector performance was in good agreement with these predictions. For a pion detection efficiency of 87%, the contamination by protons of a sample of TRD tagged pions was 2%. 15 refs., 10 figs.
Date: December 1, 1988
Creator: Errede, D.; Sheaff, M.; Fenker, H.; Lueking, L. & Mantsch, P.
Partner: UNT Libraries Government Documents Department

Design study of a medical proton linac for neutron therapy

Description: This paper describes a design study which establishes the physical parameters of the low energy beam transport, radiofrequency quadrupole, and linac, using computer programs available at Fermilab. Beam dynamics studies verify that the desired beam parameters can be achieved. The machine described here meets the aforementioned requirements and can be built using existing technology. Also discussed are other technically feasible options which could be attractive to clinicians, though they would complicate the design of the machine and increase construction costs. One of these options would allow the machine to deliver 2.3 MeV protons to produce epithermal neutrons for treating brain tumors. A second option would provide 15 MeV protons for isotope production. 21 refs., 33 figs.
Date: August 26, 1988
Creator: Machida, S. & Raparia, D.
Partner: UNT Libraries Government Documents Department

Inflation in the universe, Circa 1986

Description: The hot big bang cosmology, or the standard cosmology as it is appropriately known, is a highly successful model, providing a reliable and tested accounting of the Universe from 0.01 sec after the bang until today, some 15 Gyr later. However, very special initial data seem to be required in order to account for the observed smoothness and flatness of our Hubble volume and for the existence of the small primeval density inhomogeneities required for the formation of structure in the Universe. Inflation offers a means of accounting for these special initial data which is based upon physics at sub-planck energy scales (<<m/sub pl/ approx. = 10/sup 19/ GeV) and is motivated by contemporary ideas in particle theory. Here I review the status of the 'Inflationary Paradigm,' ''Circa,'' 1986. At present essentially all inflationary models involve a very weakly-coupled (quantified by the presence of a dimensionless parameter of order 10/sup -12/ or so) scalar field which is displaced from the minimum of its potential. Regions of the Universe where the scalar field is initially displaced from its minimum undergo inflation as the scalar field relaxes, resulting in a Universe today which resembles ours in regions much larger than our present Hubble volume (approx. =10/sup 28/ cm), but which on very large scales (>>10/sup 28/ cm) may be a highly irregular. At present, the most conspicuous blemish on the paradigm is the lack of a compelling particle physics model to implement it. Some other unresolved issues facing inflation, including the confrontation between inflation and observational data are also reviewed. 112 refs., 4 figs.
Date: December 1, 1986
Creator: Turner, M.S.
Partner: UNT Libraries Government Documents Department

Inflation in the universe

Description: The hot big bang cosmology, or the standard cosmology as it is appropriately known, is a highly successful model, providing a reliable and tested accounting of the Universe from 0.01 sec after the bang until today, some 15 Gyr later. However, very special initial data seem to be required in order to account for the observed smoothness and flatness of our Hubble volume and for the existence of the small primeval density inhomogeneities required for the formation of structure in the Universe. Inflation offers a means of accounting for these special initial data, which is based upon physics at sub-planck energy scales (<< m/sub pl/ approx. = 10/sup 19/ GeV) and is motivated by contemporary ideas in particle theory. Here I review the status of the 'Inflationary Paradigm'. At present essentially all inflationary models involve a very weakly-coupled (quantified by the presence of a dimensionless parameter of order 10/sup -12/ or so) scalar field which is displaced from the minimum of its potential. Regions of the Universe where the scalar field is initially displaced from its minimum undergo inflation as the scalar field relaxes, resulting in a Universe today which resembles ours in regions much larger than our present Hubble volume (approx. = 10/sup 28/ cm), but which on very large scales (>> 10/sup 28/ cm) may be highly irregular. The most conspicuous blemish on the paradigm is the lack of a compelling particle physics model to implement it. I also review some other unresolved issues, and discuss in detail the all important confrontation between inflation and observational data. Finally, I discuss the possibility that inflation leads to large-scale, primeval magnetic fields of sufficient strength to be of astrophysical interest. 123 refs., 4 figs.
Date: May 1, 1987
Creator: Turner, M.S.
Partner: UNT Libraries Government Documents Department

Refrigeration tests of the cryogenic system and solenoid for the Fermilab Collider Detector

Description: A refrigeration system for the 3 m phi x 5 m superconducting solenoid for the Collider Detector at Fermilab has been installed and operated with a dummy load. The nominal 600-W capacity of the system was achieved in the initial test. The solenoid and integral control dewar were tested in Japan with a 300-W refrigerator. The cooldown time was 7 days and the measured heat load of 35 W agrees well with the estimated value.
Date: July 1, 1984
Creator: Fast, R.W.; Aihara, K.; Dachniwskyj, R.I.; Kephart, R.D.; Kondo, K.; Minemura, H. et al.
Partner: UNT Libraries Government Documents Department

Cosmic string induced peculiar velocities

Description: We calculate analytically the probability distribution for peculiar velocities on scales from 10h/sup -1/ to 60h/sup -1/ Mpc with cosmic string loops as the dominant source of primordial gravitational perturbations. We consider a range of parameters ..beta..G..mu.. appropriate for both hot (HDM) and cold (CDM) dark matter scenarios. An ..cap omega.. = 1 CDM Universe is assumed with the loops randomly placed on a smooth background. It is shown how the effects can be estimated of loops breaking up and being born with a spectrum of sizes. It is found that to obtain large scale streaming velocities of at least 400 km/s it is necessary that either a large value for ..beta..G..mu.. or the effect of loop fissioning and production details be considerable. Specifically, for optimal CDM string parameters G..mu.. = 10/sup -6/, ..beta.. = 9, h = .5, and scales of 60h/sup -1/ Mpc, the parent size spectrum must be 36 times larger than the evolved daughter spectrum to achieve peculiar velocities of at least 400 km/s with a probability of 63%. With this scenario the microwave background dipole will be less than 800 km/s with only a 10% probability. The string induced velocity spectrum is relatively flat out to scales of about 2t/sub eq//a/sub eq/ and then drops off rather quickly. The flatness is a signature of string models of galaxy formation. With HDM a larger value of ..beta..G..mu.. is necessary for galaxy formation since accretion on small scales starts later. Hence, with HDM, the peculiar velocity spectrum will be larger on large scales and the flat region will extend to larger scales. If large scale peculiar velocities greater than 400 km/s are real then it is concluded that strings plus CDM have difficulties. The advantages of strings plus HDM in this regard will be explored in greater ...
Date: February 1, 1987
Creator: van Dalen, A. & Schramm, D.N.
Partner: UNT Libraries Government Documents Department

Cosmic strings in an expanding spacetime

Description: We investigate the stability of a static, infinitely long and straight vacuum string solution under inhomogeneous axisymmetric time-dependent perturbations. We find it to be perturbatively stable. We further extend our work by finding a string solutions in an expanding Universe. The back reaction of the string on the gravitational field has been ignored. The background is assumed to be a Friedman-Robertson-Walker (FRW) cosmology. By numerically integrating the field equations in a radiation and matter dominated models, we discover oscillatory solutions. The possible damping of these oscillations is discussed. For late times the solution becomes identical to the static one studied in the first part of the paper. 19 refs., 8 figs.
Date: April 1, 1987
Creator: Stein-Schabes, J.A. & Burd, A.B.
Partner: UNT Libraries Government Documents Department

Cosmology with decaying particles

Description: We consider a cosmological model in which an unstable massive relic particle species (denoted by X) has an initial mass density relative to baryons ..beta../sup -1/ identically equal rho/sub X//rho/sub B/ >> 1, and then decays recently (redshift z less than or equal to 1000) into particles which are still relativistic today (denoted by R). We write down and solve the coupled equations for the cosmic scale factor a(t), the energy density in the various components (rho/sub X/, rho/sub R/, rho/sub B/), and the growth of linear density perturbations (delta rho/rho). The solutions form a one parameter (..beta..) family of solutions; physically ..beta../sup -1/ approx. = (..cap omega../sub R//..cap omega../sub NR/) x (1 + z/sub D/) = (ratio today of energy density of relativistic to nonrelativistic particles) x (1 + redshift of (decay)). We discuss the observational implications of such a cosmological model and compare our results to earlier results computed in the simultaneous decay approximation. In an appendix we briefly consider the case where one of the decay products of the X is massive and becomes nonrelativistic by the present epoch. 21 references.
Date: September 1, 1984
Creator: Turner, M.S.
Partner: UNT Libraries Government Documents Department

Pbar Source Group summary

Description: Maxium antiproton accumulation rates have been investigated. A scheme is outlined which would accumulate more than 7E8 pbars/s ina form suitable for a peak luminosity of more than 0.5E33 /(s*cm**2) in a single SSC ring. This scheme utilizes only moderate extrapolations of present technology. Each of the stages in the accumulation process has been investigated in some detail with the same calculational tools as have been used in the CERN and Fermilab pbar sources. The results of these calculations and possibilities for improvements are discussed.
Date: January 1, 1984
Creator: Johnson, R.P. & Simpson, J.
Partner: UNT Libraries Government Documents Department

Fast processor for dilepton triggers

Description: We describe a fast trigger processor, developed for and used in Fermilab experiment E-537, for selecting high-mass dimuon events produced by negative pions and anti-protons. The processor finds candidate tracks by matching hit information received from drift chambers and scintillation counters, and determines their momenta. Invariant masses are calculated for all possible pairs of tracks and an event is accepted if any invariant mass is greater than some preselectable minimum mass. The whole process, accomplished within 5 to 10 microseconds, achieves up to a ten-fold reduction in trigger rate.
Date: January 1, 1983
Creator: Katsanevas, S.; Kostarakis, P. & Baltrusaitis, R.
Partner: UNT Libraries Government Documents Department

Instabilities of higher dimensional compactifications

Description: Various schemes for cosmological compactification of higher dimensional theories are considered. Possible instabilities which drive the ground state with static internal space to de Sitter-like expansion of all dimensions are discussed. These instabilities are due to semiclassical barrier penetration and classical thermal fluctuations. For the case of the ten dimensional Chapline-Manton action, it is possible to avoid such difficulties by balancing one-loop Casimir corrections against monopole contributions from the field strength H/sub MNP/ and fermionic condensates. 10 refs.
Date: February 1, 1987
Creator: Accetta, F.S.
Partner: UNT Libraries Government Documents Department

Hadron hadron collider group

Description: The objective of this group was to make a rough assessment of the characteristics of a hadron-hadron collider which could make it possible to study the 1 TeV mass scale. Since there is very little theoretical guidance for the type of experimental measurements which could illuminate this mass scale, we chose to extend the types of experiments which have been done at the ISR, and which are in progress at the SPS collider to these higher energies.
Date: January 1, 1982
Creator: Palmer, R.; Peoples, J. & Ankenbrandt, C.
Partner: UNT Libraries Government Documents Department

Inverse scattering problem for quarkonium systems. I. One-dimensional formalism and methodology. [bound state, algebraic technique]

Description: The inverse scattering formalism for reflectionless potentials is applied to the reconstruction of confining potentials from bound-state properties. An explicit algebraic technique is presented and tested on several one-dimensional examples. The connection with a classical problem of interacting solitons is exhibited. 27 references.
Date: December 1, 1977
Creator: Thacker, H.B.; Quigg, C. & Rosner, J.L.
Partner: UNT Libraries Government Documents Department

Determining the fifth quark's charge: the role of T leptonic widths. [Lower bounds]

Description: Lower bounds on the leptonic decay widths of T(9.4) and T'(10.0) are deduced from plausible general assumptions. It is shown that these may permit a distinction between the charge assignments e/sub Q/ = (-1/3, +2/3) for the new quark.
Date: February 1, 1978
Creator: Rosner, J.L.; Quigg, C. & Thacker, H.B.
Partner: UNT Libraries Government Documents Department

Triggering, front-end electronics, and data acquisition for high-rate beauty experiments

Description: The working group explored the feasibility of building a trigger and an electronics data acquisition system for both collider and fixed target experiments. There appears to be no fundamental technical limitation arising from either the rate or the amount of data for a collider experiment. The fixed target experiments will likely require a much higher rate because of the smaller cross section. Rates up to one event per RF bucket (50 MHz) appear to be feasible. Higher rates depend on the details of the particular experiment and trigger. Several ideas were presented on multiplicity jump and impact parameter triggers for fixed target experiments. 14 refs., 3 figs.
Date: April 1, 1988
Creator: Johnson, M. & Lankford, A.J.
Partner: UNT Libraries Government Documents Department

Real time data compactor (sparsifier) and 8 megabyte high speed FIFO for HEP

Description: A Video-Data-Acquisition-System (VDAS) has been developed to record image data from a scintillating glass fiber-optic target developed for High Energy Physics. The major components of the VDAS are a flash ADC, a ''real time'' high speed data compactor, and high speed 8 megabyte FIFO memory. The data rates through the system are in excess of 30 megabytes/second. The compactor is capable of reducing the amount of data needed to reconstruct typical images by as much as a factor of 20. The FIFO uses only standard NMOS DRAMS and TTL components to achieve its large size and high speed at relatively low power and cost.
Date: October 1, 1985
Creator: Baumbaugh, A.E.; Knickerbocker, K.L.; Wegner, C.R.; Baumbaugh, B.W. & Ruchti, R.
Partner: UNT Libraries Government Documents Department

Recent heavy particle decay in a matter dominated universe

Description: The cold matter scenario for galaxy formation solves the dark matter problem very nicely on small scales corresponding to galaxies and clusters of galaxies. It is, however, difficult to reconcile with a Universe with an Einstein-deSitter value of ..cap omega.. = 1. We will show here that cold matter and ..cap omega.. = 1 can be made compatible while retaining the feature that the Universe is matter dominated today. This is done by means of heavy (cold) particles whose decay subsequently leads to the unbinding of a large fraction of lighter clustered matter. 33 references.
Date: September 1, 1984
Creator: Olive, K.A.; Seckel, D. & Vishniac, E.
Partner: UNT Libraries Government Documents Department

Channeled particle acceleration by plasma waves in metals

Description: A solid state accelerator concept utilizing particle acceleration along crystal channels by longitudinal electron plasma waves in a metal is presented. Acceleration gradients of order 100 GV/cm are theoretically possible. Particle dechanneling due to electron multiple scattering can be eliminated with a sufficiently high acceleration gradient. Plasma wave dissipation and generation in metals are also discussed.
Date: January 1, 1987
Creator: Chen, P. & Noble, R.J.
Partner: UNT Libraries Government Documents Department

ANL stochastic-cooling experiments using the FNAL 200-MeV cooling ring

Description: Studies of stochastic momentum cooling are being conducted on the FNAL 200-MeV Storage Ring. The specific goal of the activity is to establish confidence in the theory and simulation methods used to describe the cooling process, and to develop techniques and devices suitable for use in the antiproton-accumulation scheme now planned for construction at FNAL. A summary of the activity, including hardware design, results of experiments, comparison with theory, and implications for the antiproton accumulator are presented.
Date: January 1, 1981
Creator: Hogrefe, R.L.; Kellogg, K.D.; Konecny, R.S.; Kramer, S.L.; Simpson, J.D.; Suddeth, D.E. et al.
Partner: UNT Libraries Government Documents Department

Nuclear constraints on the age of the universe

Description: In this paper a review is made of how one can use nuclear physics to put rather stringent limits on the age of the universe and thus the cosmic distance scale. As the other papers in this session have demonstrated there is some disagreement on the distance scale and thus the limits on the age of the universe (if the cosmological constant ..lambda.. = 0). However, the disagreement is only over the last factor of 2, the basic timescale seems to really be remarkably well agreed upon. The universe is billions of years old - not thousands, not quintillions but bilions of years. That our universe has a finite age is philosophically intriguing. That we can estimate that age to a fair degree of accuracy is truly impressive. No single measurement of the time since the Big Bang gives a specific, unambiguous age. Fortunately, we have at our disposal several methods that together fix the age with surprising precision. In particular, as the other papers show, there are three totally independent techniques for estimating an age and a fourth technique which involves finding consistency of the other three in the framework of the standard Big Bang cosmological model. The three independent methods are: cosmological dynamics, the age of the oldest stars, and radioactive dating. This paper concentrates on the third of the three methods, as well as go into the consistency technique.
Date: December 1, 1982
Creator: Schramm, D.N.
Partner: UNT Libraries Government Documents Department

Search for anomalous gravitational effects at the Fermilab accelerator. Progress report on E-723

Description: This is a progress report on the results of tests of a gravitational detector operated in the CO area of the Fermilab accelerator in June and July of this year. Our experience so far is that these measurements are feasible and we have set a limit on the ratio of the coupling of a long range to that of the gravitational constant of g/G < 3x10/sup 20/. The sensitivity of the experiment is evaluated to be 0.5x10/sup 6/ times lower than for the test-run and should be achieved during the forthcoming fixed target operating period.
Date: October 1, 1984
Creator: Reiner, P.; Rogers, J.; Wuensch, W.; Melissinos, A.C.; Fowler, W.B. & Kuchnir, M.
Partner: UNT Libraries Government Documents Department

Magnetic monopoles: a status report

Description: A solitary, uncorroborated Stanford candidate event is the only evidence that magnetic monpoles derives from Dirac's assertion that monopoles could explain charge quantization and the 't Hooft-Polyakov demonstration that monopoles are an inevitable consequence of many gauge theories currently being used to unify the electroweak (photon-lepton) and nuclear (quark) interactions. The monopole abundance implied by the Stanford event is in clear contradiction to bounds on their number from astronomical data. Fortunately, the already considerable and expanding arsenal of detection techniques are being fashioned to experimentally test the many open questions surrounding monopoles.
Date: March 1, 1983
Creator: Carrigan, R.A. Jr. & Trower, W.P.
Partner: UNT Libraries Government Documents Department