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Search for squarks and gluinos with the D-Zero Detector

Description: We report on a search for squarks and gluinos in p{anti p} collisions at {radical} s= 1.8 TeV using the D0 detector at Fermilab. Data corresponding to 79.2 {+-} 4.2 pb{sup -1} were examined for events with large missing transverse energy, three or more jets, and the absence of isolated leptons. No events were observed significantly in excess of Standard Model background predictions, and we place limits on the Minimal Supergravity parameters M{sub 0} and M{sub 1/2}.
Date: October 1, 1997
Creator: Abbott, B.
Partner: UNT Libraries Government Documents Department

Scheduled discoveries of 7+ high-Redshift supernovae: First cosmology results and bounds on q{sub 0}

Description: Our search for high-redshift Type Ia supernovae discovered, in its first years, a sample of seven supernovae. Using a ``batch`` search strategy, almost all were discovered before maximum light and were observed over the peak of their light curves. The spectra and light curves indicate that almost all were Type Ia supernovae at redshifts z = 0.35 - 0.5. These high-redshift supernovae can provide a distance indicator and ``standard clock`` to study the cosmological parameters q{sub 0} , {Lambda}, {Omega}{sub 0} , and H{sub 0}. This presentation and the following presentations of Kim et al. (1996), Goldhaber et al. (1996), and Pain et al. (1996) will discuss observation strategies and rates, analysis and calibration issues, the sources of measurement uncertainty, and the cosmological implications, including bounds on q{sub 0} , of these first high-redshift supernovae from our ongoing search.
Date: September 1, 1998
Creator: Perlmutter, S., FNAL
Partner: UNT Libraries Government Documents Department

Limitations of science and adaptive management

Description: Adaptive management consists in patterning human sustenancewithin the constraints of Earth and biological systems whose behavior isinherently uncertain and difficult to control. For successful adaptivemanagement, a mind-set recognizing the limitations of science isneeded.
Date: December 20, 2001
Creator: Narasimhan, T.N.
Partner: UNT Libraries Government Documents Department

Upper Limits on the Number of Small Bodies in Sedna-Like Orbits by the TAOS Project

Description: We present the results of a search for occultation events by objects at distances between 100 and 1000 AU in lightcurves from the Taiwanese-American Occultation Survey (TAOS). We searched for consecutive, shallow flux reductions in the stellar lightcurves obtained by our survey between 7 February 2005 and 31 December 2006 with a total of {approx} 4.5 x 10{sup 9} three-telescope simultaneous photometric measurements. No events were detected, allowing us to set upper limits on the number density as a function of size and distance of objects in Sedna-like orbits, using simple models.
Date: November 13, 2009
Creator: Wang, J; Lehner, M J; Zhang, Z; Bianco, F B; Alcock, C; Chen, W et al.
Partner: UNT Libraries Government Documents Department

Technicolor limits at the Tevatron

Description: Direct searches for the technicolor particles at the Tevatron collider experiments at {radical}s=1.8 TeV are described. Various color-singlet and color-octet heavy technimeson states are predicted in the recent technicolor models. The topcolor assisted technicolor model predicts new heavy gluon, top-gluon. These new particles, {rho}{sub T}, {omega}{sub T}, {pi}{sub T}, and top-gluon are expected to be produced in high energy p{anti p} collisions if they exist and they are searched in the world highest energy p{anti p} collider experiments, CDF and D0 experiments. In this report, current mass limits for these particles are shown.
Date: April 19, 1999
Creator: Handa, Takanobu
Partner: UNT Libraries Government Documents Department

Present searches for Higgs signatures at the Tevatron

Description: We present results for various searches for signatures of standard and non-standard model Higgs boson decays conducted at the collider detectors CDF and D0 using {approx}100 pb{sup -1} of integrated luminosity each from the Tevatron collider Run 1 (1992-96) at {radical}s=1.8 TeV. No evidence for a Higgs boson decay is found and various limits are set.
Date: August 1, 1997
Creator: Groer, L.
Partner: UNT Libraries Government Documents Department

Intensity Limitations in Fermilab Main Injector

Description: The design beam intensity of the FNAL Main Injector (MI) is 3 x 10{sup 13} ppp. This paper investigates possible limitations in the intensity upgrade. These include the space charge, transition crossing, microwave instability, coupled bunch instability, resistive wall, beam loading (static and transient), rf power, aperture (physical and dynamic), coalescing, particle losses and radiation shielding, etc. It seems that to increase the intensity by a factor of two from the design value is straightforward. Even a factor of five is possible provided that the following measures are to be taken: an rf power upgrade, a {gamma}{sub t}-jump system, longitudinal and transverse feedback systems, rf feedback and feedforward, stopband corrections and local shieldings.
Date: June 1, 1997
Creator: Chan, W.
Partner: UNT Libraries Government Documents Department

Nuclear Structure at the Limits

Description: One of the frontiers of today�s nuclear science is the �journey to the limits� of atomic charge and nuclear mass, of neutron-to-proton ratio, and of angular momentum. The tour to the limits is not only a quest for new, exciting phenomena, but the new data are expected, as well, to bring qualitatively new information about the fundamental properties of the nucleonic many-body system, the nature of the nuclear interaction, and nucleonic correlations at various energy-distance scales. In this series of lectures, current developments in nuclear structure at the limits are discussed from a theoretical perspective, mainly concentrating on medium-mass and heavy nuclei.
Date: January 12, 1998
Creator: Nazarewicz, W.
Partner: UNT Libraries Government Documents Department


Description: OAK-B135 Global gyrokinetic simulations of turbulence include physical effects that are not retained in local flux-tube simulations. nevertheless, in the limit of sufficiently small {rho}* (gyroradius compared to system size) it is expected that a local simulation should agree with a global one (at the local simulation radius) since all effects that are dropped in the local simulations are expected to vanish as {rho}* {yields} 0. In this note, global simulations of a well-established test case are indeed shown to recover the flux-tube limit at each radius.
Date: October 1, 2003
Partner: UNT Libraries Government Documents Department

Are there clouds in the BLR? Keck observations of NGC 4151

Description: We search for a direct signature of discrete ``clouds`` in the broad line region (BLR) of the Seyfert galaxy NGC 4151. For this purpose we apply cross correlation (CC) analysis to a high resolution KECK spectrum of the galaxy. No such signature is found in the data. In order for cloud models to be compatible with this result, there must be at least {approximately} 3 x 10{sup 7} emitting clouds in the BLR, where the limit is based on simulation of a homogeneous cloud population. More realistic distributions increase the lower limit to above 10{sup 8} . These numbers are an order of magnitude improvement on our previous limit from Mrk 335, where the improvement comes from higher S/N, broader lines, and refined simulations. Combined with the predicted upper limit for the number of emitting clouds in NGC 4151 (10{sup 6} - 10{sup 7}), the derived lower limit puts a strong constraint on the cloud scenario in the BLR of this object. Similar constraints can be placed on models where the emission originates in streams and sheets. Thus, this investigation suggests that the BELs in NGC 4151, and by extension in all AGNs, are not made of an ensemble of discrete independent emitters.
Date: March 1998
Creator: Arav, N.
Partner: UNT Libraries Government Documents Department

A Lower Bound on Neutrino Mass And Its Implication on the Z-Burst Scenario

Description: We show that the cascade limit on ultra high energy cosmic neutrino (UHEC/nu) flux imposes a lower bound on the neutrino mass provided that super-GZK events of ultra high energy cosmic rays (UHECRs) are produced from Z-bursts. Based on the data from HiRes and AGASA, the obtained neutrino mass lower bound violates its existing cosmological upper bound. We conclude that the Z-burst cannot be the dominant source for the observed super-GZK UHECR events. This is consistent with the recent ANITA-lite data.
Date: January 11, 2006
Creator: Lai, Kwang-Chang; /Taiwan, Natl. Taiwan U.; Chen, Pisin & /KIPAC, Menlo Park
Partner: UNT Libraries Government Documents Department

Time-step limits for a Monte Carlo Compton-scattering method

Description: We perform a stability analysis of a Monte Carlo method for simulating the Compton scattering of photons by free electron in high energy density applications and develop time-step limits that avoid unstable and oscillatory solutions. Implementing this Monte Carlo technique in multi physics problems typically requires evaluating the material temperature at its beginning-of-time-step value, which can lead to this undesirable behavior. With a set of numerical examples, we demonstrate the efficacy of our time-step limits.
Date: January 1, 2009
Creator: Densmore, Jeffery D; Warsa, James S & Lowrie, Robert B
Partner: UNT Libraries Government Documents Department

Confidence Calculation with AMV+

Description: The iterative advanced mean value algorithm (AMV+), introduced nearly ten years ago, is now widely used as a cost-effective probabilistic structural analysis tool when the use of sampling methods is cost prohibitive (Wu et al., 1990). The need to establish confidence bounds on calculated probabilities arises because of the presence of uncertainties in measured means and variances of input random variables. In this paper an algorithm is proposed that makes use of the AMV+ procedure and analytically derived probability sensitivities to determine confidence bounds on calculated probabilities.
Date: February 19, 1999
Creator: Fossum, A.F.
Partner: UNT Libraries Government Documents Department

Ultrahigh-intensity laser: physics of the extreme on a tabletop

Description: This paper reviews the development of ultrahigh-intensity laser technology from the early 1960`s to the present, explaining the obstacles to each increase in intensity and the technical means used to overcome them. These included the shortening of pulses, mode locking, and chirped pulse amplification (CPA). The particular technical advances that make CPA possible included the invention of matched pulse stretchers and compressors and the development of ultrabroadband gain media. The paper then discusses the generation of ultrashort pulses and their characteristics. It then moves on to the Petawatt laser, which incorporates the CPA technology. It then addresses the question of whether it is possible to forecast the ultimate peak power that can be achieved by a laser system of a given size. Applications of ultrahigh-intensity lasers in different physical regimes are discussed.
Date: October 10, 1997
Creator: Mourou, G.A.; Barty, C.P. & Perry, M.D.
Partner: UNT Libraries Government Documents Department

Evaluation of kinetic phosphorescence analysis for the determination of uranium

Description: In the past, New Brunswick Laboratory (NBL) has used a fluorometric method for the determination of sub-microgram quantities of uranium. In its continuing effort to upgrade and improve measurement technology, NBL has evaluated the commercially-available KPA-11 kinetic phosphorescence analyzer (Chemchek, Richland, WA). The Chemchek KPA-11 is a bench-top instrument which performs single-measurement, quench-corrected analyses for trace uranium. It incorporates patented kinetic phosphorimetry techniques to measure and analyze sample phosphorescence as a function of time. With laser excitation and time-corrected photon counting, the KPA-11 has a lower detection limit than conventional fluorometric methods. Operated with a personal computer, the state-of-the-art KPA-11 offers extensive time resolution and phosphorescence lifetime capabilities for additional specificity. Interferences are thereby avoided while obtaining precise measurements. Routine analyses can be easily and effectively accomplished, with the accuracy and precision equivalent to the pulsed-laser fluorometric method presently performed at NBL, without the need for internal standards. Applications of kinetic phosphorimetry at NBL include the measurement of trace level uranium in retention tank, waste samples, and low-level samples. It has also been used to support other experimental activities at NBL by the measuring of nanogram amounts of uranium contamination (in blanks) in isotopic sample preparations, and the determining of elution curves of different ion exchange resins used for uranium purification. In many cases, no pretreatment of samples was necessary except to fume them with nitric acid, and then to redissolve and dilute them to an appropriate concentration with 1 M HNO{sub 3} before measurement. Concentrations were determined on a mass basis ({micro}g U/g of solution), but no density corrections were needed since all the samples (including the samples used for calibration) were in the same density matrix (1 M HNO{sub 3}). A statistical evaluation of the determination of uranium using kinetic phosphorimetry is described in this report, along with ...
Date: December 1, 1997
Creator: Croatto, P.V.; Frank, I.W.; Johnson, K.D.; Mason, P.B. & Smith, M.M.
Partner: UNT Libraries Government Documents Department

Behavior of the finite-sized, three-dimensional, Ising model near the critical point

Description: Recent work showing the validity of hyperscaling involved results for finite size systems very near the critical point. The authors study this problem in more detail, and give estimators related to the Binder cumulant ratio which seem to approach the critical temperature from above and below. Based on these results, they estimate that the renormalized coupling constant, computed for the temperature fixed at the critical temperature and then taking the large system-size limit, is about 4.9 {+-} 0.1, and give a likely lower bound for it of 4.5. These estimates are argued to suffice to show the validity of hyperscaling.
Date: May 1, 1996
Creator: Baker, G.A. Jr. & Gupta, R.
Partner: UNT Libraries Government Documents Department

Temperature limits based on the saturation temperature in Hanford waste storage tanks

Description: This report calculates limits on the measured temperature readings to limit the occurrence of saturation temperatures in Hanford waste storage tanks. The results in this report show that the temperature reported by a thermocouple tree in a double-shell tank can be significantly below the maximum waste temperature and that provisions should be made for that offset in any tank temperature monitoring program. The results for single-shell tanks show that some tanks may be at or above the saturation temperature.
Date: October 14, 1996
Creator: Bander, T.J.
Partner: UNT Libraries Government Documents Department

Tight bounds on the size of neural networks for classification problems

Description: This paper relies on the entropy of a data-set (i.e., number-of-bits) to prove tight bounds on the size of neural networks solving a classification problem. First, based on a sequence of geometrical steps, the authors constructively compute an upper bound of O(mn) on the number-of-bits for a given data-set - here m is the number of examples and n is the number of dimensions (i.e., R{sup n}). This result is used further in a nonconstructive way to bound the size of neural networks which correctly classify that data-set.
Date: June 1, 1997
Creator: Beiu, V. & Pauw, T. de
Partner: UNT Libraries Government Documents Department

Discovery mass reach for excited quarks at hadron colliders

Description: If quarks are composite particles then excited states are expected. We estimate the discovery mass reach as a function of integrated luminosity for excited quarks decaying to dijets at the Tevatron the mass reach is 0.94 TeV for Run 11 (2 fb{sup -1}) and 1. 1 TeV for TeV33 (30 fb{sup -1}). At the LHC the mass reach is 6.3 TeV for 100 fb{sup -1}. At a VLHC with a center of mass energy {radical}s, of 50 TeV (200 TeV) the mass reach is 25 TeV (78 TeV) for an integrated luminosity of 10{sup 4} fb{sup -1}. However, an excited quark with a mass of 25 TeV would be discovered at a hadron collider with {radical}s = 100 TeV and an integrated luminosity of 13 fb{sup -1}, illustrating a physics example where a factor of 2 in machine energy is worth a factor of 1000 in luminosity.
Date: September 10, 1996
Creator: Harris, R.M.
Partner: UNT Libraries Government Documents Department

Beam tube vacuum in 100 TeV hadron colliders

Description: Bounds on the beam tube gas pressure and the required pumping speed are estimated for {approximately} 2 T low field (LF) and {approximately} 12 T high field (HF) 100 TeV center-of-mass hadron colliders. In both cases photodesorption by synchrotron radiation is the dominant source of gas. Assuming beam-gas scattering limited luminosity lifetime five times the IP scattering lifetime, the required CO equivalent beam tube pressure is 0.25 nTorr for LF and 1.8 nTorr for HF, ambient room temperature equivalent. The CO equivalent pumping speeds required to achieve this pressure within a reasonable beam conditioning time (a few tenths of an operational year at design intensity) are estimated to be {approximately} 300 l/s-m for LF and {approximately} 40 l/s-m for HF. For the LF case with a superferric warm iron magnet, the beam tube is at ambient room temperature and a distributed NEG plus lumped ion or cryo pump system is considered. The size of antechamber needed, ID {approximately} 6 cm, requires that it be located outside the {approximately} 2 cm C-coil magnet gap. Lumped pumps for pumping CH{sub 4} need to be spaced at {approximately} 20 m intervals on the antechamber. For the HF case the likely beam tube temperature is 15--20 K and cryopumping with a beam screen system is considered. The necessary pumping speed can be achieved with slots covering {approximately} 2% of the beam screen surface.
Date: April 1, 1997
Creator: Turner, W.C.
Partner: UNT Libraries Government Documents Department