123 Matching Results

Search Results

Advanced search parameters have been applied.

Silicon detector readout system using commercially available items

Description: The basic properties of silicon detectors are briefly noted, including bulk and electrical properties. Thermal and shot noise in front end amplifiers is discussed. The configuration of detectors and preamps is then briefly described. A detector test is described and results are given. (LEW)
Date: May 1, 1986
Creator: Green, D.
Partner: UNT Libraries Government Documents Department

/bar p/p collider physics

Description: This note encompasses a set of six lectures given at the summer school held at Campos Do Jordao in January of 1989 near Sao Paulo, Brazil. The intent of the lectures was to describe the physics of /bar p/p at CERN and Fermilab. Particular attention has been paid to making a self contained presentation to a prospective audience of graduate students. Since large Monte Carlo codes might not be available to all members of this audience, great reliance was placed on ''back of the envelope estimates.'' Emphasis was also placed on experimental data rather than theoretical speculation, since predictions for, for example, supersymmetric particle production are easily obtained by transcription of formulae already obtained. 9 refs., 67 figs., 2 tabs.
Date: March 1, 1989
Creator: Green, D.
Partner: UNT Libraries Government Documents Department

Dijet spectroscopy at high luminosity

Description: A study of the dijet mass resolution has been made appropriate to high luminosity operation. As a benchmark, the mass resolution of W {yields} jj for a Higgs boson of 800 GeV has been optimized for no, eight, and sixteen overlapping minbias events. A factor of 2.5 degradation in M{sub jj} width is seen. 6 refs., 10 figs.
Date: July 1, 1990
Creator: Green, D.
Partner: UNT Libraries Government Documents Department

SDC at high luminosity

Description: Why is it prudent to plan for a luminosity (L) of >10{sup 34}/(cm{sup 2}sec) from the beginning First, the SSC is easily capable of attaining high luminosity. In comparison, for {bar p}p machines such as the Tevatron, increases in L are difficult. Second, after early runs at design luminosity, the only simple upgrade to a general purpose detector is an increase in luminosity. Third, and most important, the only known model independent physics goal of SSC is in the electroweak sector; the ZZ scattering amplitude reaches the unitarity bound for {radical}{cflx s} {approx equal} 3 TeV. In order to reach this mass range, and assure that some new physics is found, high luminosity running is needed. Since high luminosity running is desirable and easily attainable, it is inevitable. Therefore, one should build the hooks'' for upgrades to high L into the SDC from the beginning. The experience of CDF is that if this is not done, upgrades can be painful. Specifically, if possible, SDC should make sure that the chosen technologies allow high L operation. The time to plan for the whole useful lifetime of SDC is from the beginning. 9 refs., 6 figs.
Date: May 1, 1990
Creator: Green, D.
Partner: UNT Libraries Government Documents Department

Tables of thermodynamic functions for gaseous thorium, uranium, and plutonium oxides

Description: Measured and estimated spectroscopic data for thorium, uranium, and plutonium oxide vapor species have been used with the methods of statistical mechanics to calculate thermodynamic functions. Some inconsistencies between spectroscopic data and some thermodynamic data have been resolved by recalculating ..delta..H/sup 0//sub f/ (298.15/sup 0/K) values for the vapor species of these oxides. Evaluation of the uncertainties in data, methods of estimating molecular parameters, and effects of assumptions have been discussed elsewhere. The tables of thermodynamic functions that were reported earlier have been revised principally because the low-frequency vibrational modes of UO/sub 2/ and UO/sub 3/ have now been measured. These new empirical data resulted in changes in the electronic contributions to the calculated thermodynamic functions of UO/sub 2/ and the estimated vibrational contributions for PuO/sub 2/. In addition, some minor changes have been made in the methods of calculation of the electronic contributions for all molecules.
Date: March 1, 1980
Creator: Green, D.W.
Partner: UNT Libraries Government Documents Department

Experimental electro-thermal method for nondestructively testing welds in stainless steel pipes

Description: Welds in austenitic stainless steel pipes are notoriously difficult to nondestructively examine using conventional ultrasonic and eddy current methods. Survace irregularities and microscopic variations in magnetic permeability cause false eddy current signal variations. Ultrasonic methods have been developed which use computer processing of the data to overcome some of the problems. Electro-thermal nondestructive testing shows promise for detecting flaws that are difficult to detect using other NDT methods. Results of a project completed to develop and demonstrate the potential of an electro-thermal method for nondestructively testing stainless steel pipe welds are presented. Electro-thermal NDT uses a brief pulse of electrical current injected into the pipe. Defects at any depth within the weld cause small differences in surface electrical current distribution. These cause short-lived transient temperature differences on the pipe's surface that are mapped using an infrared scanning camera. Localized microstructural differences and normal surface roughness in the welds have little effect on the surface temperatures.
Date: January 19, 1979
Creator: Green, D. R.
Partner: UNT Libraries Government Documents Department

Calculation of the thermodynamic properties of fuel-vapor species from spectroscopic data

Description: Measured spectroscopic data, estimated molecular parameters, and a densty-of-states model for electronic structure have been used to calculate thermodynamic functions for gaseous ThO, ThO/sub 2/, UO, UO/sub 2/, UO/sub 3/, PuO, and PuO/sub 2/. Various methods for estimating parameters have been considered and numerically evaluated. The sensitivity of the calculated thermodynamic functions to molecular parameters has been examined quantitatively. New values of the standard enthalpies of formation at 298.15/sup 0/K have been derived from the best available ..delta..G/sup 0//sub f/ equations and the calculated thermodynamic functions. Estimates of the uncertainties have been made for measured and estimated data as well as for various mathematical and physical approximations. Tables of the thermodynamic functions to 6000/sup 0/K are recommended for gaseous thorium, uranium, and plutonium oxides.
Date: September 1, 1980
Creator: Green, D.W.
Partner: UNT Libraries Government Documents Department

Vapor pressures and vapor compositions in equilibrium with hypostoichiometric uranium dioxide at high temperatures

Description: Thermodynamic functions of the gaseous species, thermodynamic functions of the condensed phase, and an oxygen-potential model have been combined to calculate the vapor pressures and vapor compositions in equilibrium with condensed-phase UO/sub 2-x/ for 1500 less than or equal to T less than or equal to 6000 K and 0 less than or equal to x less than or equal to 0.5. A method for extending the oxygen-potential model of Blackburn to the liquid region has been derived and evaluated. New thermodynamic functions of the UO/sub 2/ condensed phase have been derived from the best available data, including the heat capacity recommended by Fink.
Date: June 1, 1981
Creator: Green, D.W. & Leibowitz, L.
Partner: UNT Libraries Government Documents Department

Feasibility study on infrared electro-thermal NDE of stainless steel

Description: Electro-thermal examination, a branch of thermal testing (TT), is a promising method being developed for NDE of stainless steel welds. This report describes the first phase of development; i.e., preliminary demonstration and laboratory evaluation of the method's sensitivity to notches in Type 304 stainless steel plate specimens. It also includes a description of the basic principles, together with a description of the hardware and experimental results showing that electrical discharge machined notches down to 0.16 cm (0.06 in.) long x 0.08 cm (0.03 in.) deep were detected. A qualitative technique for interpreting the test results to determine whether defects are at the surface or deeper within the material is demonstrated. (auth)
Date: November 1, 1975
Creator: Green, D.R. & Hassberger, J.A.
Partner: UNT Libraries Government Documents Department

Development of a method for evaluating carbon dioxide miscible flooding prospects. Final report

Description: Research was undertaken to develop a method of evaluating reservoirs as prospects for carbon dioxide flooding. Evaluation was to be based on a determination of miscibility pressure and displacement efficiency under idealized conditions. To reach the objective, project work was divided into five areas: (1) conducting of phase-equilibrium studies of carbon dioxide with synthetic oils; (2) application of an equation of state to simulate the phase behavior of carbon dioxide - oil systems; (3) conducting of linear displacements of crude oils and synthetic oils by carbon dioxide in a slim-tube apparatus; (4) application of the equation of state, the phase-behavior data and slim-tube data to develop a method of screening reservoirs for carbon dioxide flooding based on determination of minimum miscibility pressure and displacement efficiency; (5) development of a one-dimensional mathematical model, based on the equation of state, for application in conjunction with the results of Parts 1 to 4. The accomplishments for these five areas are discussed in five chapters. 44 references, 90 figures, 42 tables.
Date: March 1, 1985
Creator: Green, D.W. & Swift, G.W.
Partner: UNT Libraries Government Documents Department

Simple model of calorimeter sampling response in a magnetic field

Description: The fact that plastic scintillator ``brightens`` in the presence of a magnetic field has been known for some time. Recently, measurements have been extended to larger field strengths ( < 20 T ) and a saturation of the effect was observed for fields > 2.5 T. Thus the active element in a sampling calorimeter may be expected to have a signal increase of {approx} 6-8 % when immersed in fields of strength > 2.5 T. This brightening of the scintillator is independent of the orientation of the field. In addition to these effects, there has been reported an increase in the signal seen by sampling calorimeters due to incident electrons in the presence of a magnetic field. In contrast to the brightening effect, there does not appear to be saturation at the field strengths used (B < 2.5 T) and the magnitude of the effect appears to be somewhat larger than that expected from brightening alone, {approx}20% at 2.5 T. A comprehensive program has been mounted to study these problems in the context of CMS calorimetry and new results are expected momentarily. In particular, field strengths up to 3 T are employed, and field orientations parallel and perpendicular to the incident particle are to be explored.
Date: October 1, 1996
Creator: Green, D.
Partner: UNT Libraries Government Documents Department

Hadron calorimeter performance with a PbWO4 EM compartment

Description: The CMS detector[1] at the LHC has chosen PbWO4 in order to achieve the superior photon energy resolution which is crucial in searching for the 2 photon decay of low mass Higgs bosons. The hadronic compartment is thought to be Cu absorber, since one is immersed in a 4 T magnetic field, read out by scintillator tiles coupled to wavelength shifter (WLS) fibers. The combined performance of this calorimeter is of interest in the study of jets and missing transverse energy (neutrino, SUSY signatures). For this reason, a test was made of the electromagnetic (EM) compartment combined with a reasonable approximation to the baseline HCAL ``barrel`` calorimeter. Data was taken in the H4 CERN beamline. The EM compartment was a 7 {times} 7 square array of PbWO4 crystals, which for the purposes of this study are considered as a single readout in depth (or ``compartment``) [2]. The HCAL module consisted of large scintillator plates with 24 individual longitudinal readout channels. The EM compartment was followed by 10 Cu plates each 3 cm thick, followed by 9 Cu plates each 6 cm thick. This set of absorber plates represented the HCAL compartments inside the coil. The coil itself [1] was approximated as Al and Fe plates, of a total thickness of about 1.4 absorption lengths. The coil mockup was sampled and then followed by 4 plates of 8 cm thick Cu, each with an individual readout which represented a test of the ``Tailcatcher`` concept.
Date: January 1996
Creator: Green, D.
Partner: UNT Libraries Government Documents Department

Uniformity requirements in CMS hadron calorimetry

Description: Practical considerations of calorimeter systems require a specification of the allowed manufacturing tolerances. The tightness of these requirements directly makes an impact on the assembly costs of the calorimeter. For that reason, a precise and well defined set of criteria is mandatory. In addition, the intrinsic limitations of hadron calorimetry define the level of accuracy needed in the manufacture of such devices. Therefore, considerations of the limitations on energy measurement accuracy due to Physics should define the needed level of effort to produce a uniform calorimetric device.
Date: February 1, 1996
Creator: Green, D.
Partner: UNT Libraries Government Documents Department

Effect of dead material in a calorimeter

Description: The existence of dead material in any practical calorimeter system is simply a fact of life. The task for the designer, then, is to understand the impact on the Physics in question, and strive to minimize it. The aim of this note is to use the ``Hanging File`` test data, which has fined grained individual readout of about 100 depth segments, to explore impact of dead material on the mean and r.m.s. of the hadronic distribution. The amount and location of the dead material is varied. It important to remember that the Hanging File data was calibrated, EM to HCAL compartment, so as to minimize the electron to pion energy dependence. In practical terms e/pie was made = 1.0 at an incident energy of about 100 GeV. Note that the PB(EM) + FE(HCAL) calorimeter was not a compensating device.
Date: October 1, 1995
Creator: Green, D.
Partner: UNT Libraries Government Documents Department

Physics requirements for LHC/SSC calorimetry

Description: The goal of the next generation of collider detectors is to study the origin of electroweak symmetry breaking. The mass scale for this study is roughly 1 TeV. No matter what the details of the mechanism, one can be confident that new phenomena will occur, since weak interactions become strong, i.e., violate partial wave unitarity, at that mass scale. The partial wave amplitude for ee{yields} WW scattering is; ao{approximately}4{phi}/{alpha}{sub w}(M{sub w}/M){sup 2}, ao{approximately}1 if M {approximately}1 TeV. Therefore, the detectors for LHC/SSC must be able to confront this mass scale. In particular, the electroweak dynamics is such that the study of gauge boson pairs has a high priority. Given that the simplest decay modes for gauge boson are into leptons, the new detectors will naturally tend to optimize performance for leptons.
Date: October 1, 1991
Creator: Green, D.
Partner: UNT Libraries Government Documents Department

Dijet mass resolution and compensating calorimetry

Description: The calorimetry for SSC detectors has as its role the detection of the basic particles of the Standard Model. Those germane to calorimetry are quarks, photons, electrons, and gluons. Note that all the hadronic entities appear in the calorimetry as jets. The detection of single hadrons belongs to a past era when quark molecules'' were the focus of intense study. Thus, the goal of calorimetry at the SSC must be the study of jets. In particular, one must understand what defines the limits of accuracy of the jets. If there are intrinsic physical processes which limit the precision of jet measurements, then calorimetry which is more accurate is unnecessary if not wasteful. 5 refs., 5 figs.
Date: May 1, 1991
Creator: Green, D.
Partner: UNT Libraries Government Documents Department

Effect of inert material on ZZ mass resolution for H yields ZZ yields eeee

Description: A detector with a modest sized magnetic field volume will, of necessity, have inert material (solenoid coil) in front of the calorimetry. It is therefore crucial to assess the impact of that material on the physics of interest. Since the thickness of material is of order a radiation length, Xo, and only a fraction of a nuclear interaction length, the physics topics concern the EM calorimetry. In this note, a Higgs boson with a wide variety of masses is used as a paradigm of SSC physics. Low mass Higgs bosons approximate the kinematics of inclusive Z production, while high mass Higgs bosons probe the extremes of phase space to be explored at the SSC. The scale of interest is the natural width of the Z, since backgrounds will increase should the resolution due to the inert material exceed this basic scale. 4 refs., 3 figs.
Date: April 1, 1991
Creator: Green, D.
Partner: UNT Libraries Government Documents Department

Infrared NDT methods applied to solar cell and panel characterization

Description: Infrared nondestructive testing (NDT) methods are described that have a good potential for providing valuable data concerning solar cell or panel characteristics without requiring contact with the photovoltaic device. Preliminary tests with cells and panels were conducted and the infrared NDT results are presented and discussed. (MHR)
Date: October 20, 1978
Creator: Green, D. R. & Olsen, L. C.
Partner: UNT Libraries Government Documents Department

The effects of cracks on calorimeter response in the SDC dogleg'' design

Description: In an initial attempt to set the scale for cracks, the reaction H(800) [yields] ZZ [yields] (q + q) [yields] ([tau]l +[tau]2) [yields] ([rho]l + [nu]i) + ([rho]2 + [nu]2) was studied. The figure of merit was taken to be the Z transverse mass, i.e. the mass of ([rho]1 + 2 + E[sub T]). With no cracks in the coverage save the beam holes at [eta] = 5, this quantity has a fractional spread of [approximately] 12%. The additional contribution of cracks was unfolded in quadrature. Clearly, the scale where the effects of cracks becomes important for this physics process is a few cm (few % of azimuth). At a full crack width of 4 cm, the additional contribution due to cracks is comparable to all the other effects intrinsic to the decay kinematics and to the SDC baseline detector. Note that these cracks are complete'', in that it is assumed that all energy incident on them is completely lost Since the barrel wedge in SDC will have an irreducible dead space of width, [approximately] 1 cm due to fiber routing, light tightening, etc., it was decided to study a dogleg'' geometry.
Date: November 1, 1992
Creator: Green, D.
Partner: UNT Libraries Government Documents Department

Dead material and energy measurements in hadronic calorimeters

Description: Often the question arises as to where is the optimal place to locate [open quotes]dead[close quotes] material in a calorimeter. This material may be needed for structural reasons, for example. There needs to be a quantified answer to the question of what damage this [open quotes]dead[close quotes] material does to the performance of a calorimeter. For the purposes of this note, a hadronic calorimeter (HAD) is characterized by the mean and standard deviation of the energy measurement made by that detector.
Date: January 1, 1993
Creator: Green, D.
Partner: UNT Libraries Government Documents Department