Superconducting Super Collider Research Articles

Three-dimensional magnetic field produced by an axisymmetric iron yoke (SSC quadrupole)

A computational procedure in which separate analyses are performed for conductor and high-permeability iron yoke has been developed for calculating the 3-D magnetic field components. Whereas the field components of the isolated 3-D current array can be evaluated at all desired points through the use of a 3-D Biot-Savart law program, the authors have developed a method for calculating the supplemental field (the image field) that will arise as a result of the presence (coaxially) of a surrounding high-permeability magnetic yoke with an axially symmetric bore. The proposed technique is illustrated by its application to the SSC (Superconducting Super Collider) main quadrupole.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Using the top quark for testing standard-model polarization and CP predictions.

Once top quarks are found, because they are heavy they will allow many new tests of the standard model (SM) and new probes of physics at the 100-GeV scale. In this paper we show how to test the standard-model QCD predictions for the transverse polarization of a top quark produced at the Fermilab Tevatron, Superconducting Super Collider, CERN Large Hadron Collider, and the Next Linear Collider. We also examine the most general form of the $W\ensuremath{-}t\ensuremath{-}b$ vertex, and show how to detect effects of non-SM operators. Ways of detecting non-SM $\mathrm{CP}$-violation effects in either the production or the decay of the top quarks and top antiquarks are examined.

Performance of trim coils made by a novel method

A precision, automated method of manufacturing trim coils on printed circuit technology has been developed. Excellent quench performance and increased radiation resistance have been achieved in recently tested models of sextupole trim coils developed for operation inside 40-mm-aperture SSC (Superconducting Super Collider) Main Collider dipoles. >

Half cell 'SSC' 40 mm aperture magnet string

An attempt was made to verify that SSC (Superconducting Super Collider) magnets (dipoles) can be installed, leak checked, cooled to LHe temperature, energized, and quenched as a string in a tunnel type environment. The data given here were obtained during a controls and system check-out run. This run basically had all of the proper accelerator controls as well as, in the background, an independent magnet test facility monitor and protection. Early data are presented on the heat loads of some circuits and quench performance of the two magnet strings used. The heat loads found were high and the quench performance appeared to be better than expected. After disassembly occurred, obvious causes were present for some of the heat load. >

Test results of BNL built 40-mm aperture, 17-m-long SSC collider dipole magnets

Eleven 17-m-long, 40-mm-aperture SSC (Superconducting Super Collider) R&D superconducting collider dipole magnets, built at BNL (Brookhaven National Laboratory), have been extensively tested at BNL and Fermilab during 1990-1. Quench performance of these magnets and details of their mechanical behavior are presented. Although the quench performance of the most recent magnets shows slightly more quenches than expected, there is now a better understanding of the mechanical behavior of these magnets. The baseline design leads to reasonable quench performance. The quench performance of the DC series magnets seems to indicate a strong sensitivity to change in design parameters, key among them being the collar-yoke interference and the coil end loading. >

超電導超大型粒子加速器(SSC)計画における技術と材料

超電導超大型粒子加速器(SSC)計画における技術と材料

Magnetic field in the end region of the SSC quadrupole magnet

Recent advances in methods of computing magnetic fields have made it possible to study the field in the end region of the SSC (Superconducting Super Collider) quadrupole magnet in detail. The placement of conductor in the straight section, away from the ends, was designed to produce a practically pure quadrupole field in the two-dimensional sense. The ends of the coils were designed to produce a practically pure quadrupole field in the integral sense using a method that ignores the presence of the iron yoke. Subsequently, the effect of the presence of the yoke on the field was analyzed. The authors present the end configuration together with the computed integrated multipole components, local multipole components, and local field components. A comparison with measurements is included. >

Tests of Fermilab built 40 mm aperture full length SSC dipole magnets

Several 40-mm-aperture, 17-m-long dipoles have been built by Fermilab as developmental prototypes for the Superconducting Super Collider (SSC). These magnets have an external inner-outer coil splice design, a collet style end clamp assembly, a new, analytically designed minimum stress coil end design, and a new insulation system which does not employ shims or 'shoes'. In addition, the magnets were built using production-style tooling. The magnets were tested at the Fermilab Magnet Testing Facility. Quench testing and mechanical measurement results are presented and analyzed with emphasis on the new design and fabrication features of these magnets. The performance of these magnets was very good from a quench and mechanical behavior standpoint. The magnets did not exhibit excessive training behavior and only one training quench was below the nominal operating current. The coil prestress remained positive to >7 T in both magnets and most of the quenches originated in the high field region of the pole turn.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

A fast cluster finding system for future HEP experiments

The recent rapid improvements in performance of commercially available digital signal processors (DSP) and data-driven array processors make their efficient integration into the front-end trigger and data acquisition electronics of future detectors for high energy physics (HEP) attactive. These devices provide an alternative to VLSI circuits such as ASICs (application specific integrated circuit) for this special purpose application. A parallel-processing system based on data-driven array processors, digital signal processors (DSP) and Transputers for trigger decision, data acquisition and compaction is described. The system is modular and suitable for all calorimeter sizes including the ones proposed for the LHC (large hadron collider) and SSC (superconducting supercollider) experiments. The aim is to give full programmability to the trigger decisions and data compaction, over the entire calorimeter at the single-channel granularity level, with no boundary limitation. The fast cluster finding system is based on two cooperating levels, the higher one utilizing FDPP (fast digital parallel processing modules), and the lower one, the new data-controlled array processor for video signal processing, DataWave. The proposed architecture assigns one DataWave processing element (PE) to each calorimeter channel and one FDPP module for every 256 DataWave PE. These numbers have been chosen for optimum performance but may be changed. Fast inter-processor communication within the DataWave array overcomes the problem of overlapping areas, and effectively provides a continuous array of PEs. Local maxima, along with their total energy, are found in a very short time by the data-driven array processors. These are easily selected and transfered, with the data of their region of interest, to a higher-level DSP array-processor system even if part of the data falls outside the region originally attributed to a particular FDPP.

Silicon tracker for the superconducting supercollider

This is a status report on the design of a large silicon tracking detector for the superconducting supercollider (SSC). We present our design, the principles on which it is based and initial work on the mechanical support structure for the detectors.

Walking technicolor signatures at hadron colliders.

Aspects of the dynamics of walking technicolor models are expected to have important consequences for technihadron production at hadron colliders. Hard-mass enhancements characteristic of walking technicolor raise technipion (${\ensuremath{\pi}}_{T}$) masses relative to technirho (${\ensuremath{\rho}}_{T}$) masses so that the decays ${\ensuremath{\rho}}_{T}\ensuremath{\rightarrow}{\ensuremath{\pi}}_{T}{\ensuremath{\pi}}_{T}$ are either suppressed or forbidden altogether. Thus, ${\ensuremath{\rho}}_{T}$ can be unusually narrow with unconventional decay modes. Large weak isospin breaking in $U$- and $D$-technifermion masses (required for $t\ensuremath{-}b$ splitting) leads to neutral ${\ensuremath{\rho}}_{T}$ and ${\ensuremath{\pi}}_{T}$ that are ideally mixed. Finally, multiscale models of walking technicolor in which the light-scale technifermions carry ordinary SU(3) color can have color-octet ${\ensuremath{\rho}}_{T}'\mathrm{s}$ which are produced strongly in parton-parton collisions and are within reach of the Fermilab Tevatron. These would appear as narrow, well-separated ${\ensuremath{\rho}}_{\overline{D}D}$ and ${\ensuremath{\rho}}_{\overline{U}U}$ resonances in dijet production or in ${\ensuremath{\pi}}_{T}{\ensuremath{\pi}}_{T}$ production with a limited number of final states. These expectations are illustrated in a multiscale model containing both techniquarks and technileptons at the light scale. Depending on assumptions that determine the fundamental chiral-symmetry-breaking mass parameters of the model, we find two generic phenomenologies: (A) ${\ensuremath{\rho}}_{\overline{D}D}$ with a mass of 200-250 GeV decaying exclusively to dijets and ${\ensuremath{\rho}}_{\overline{U}U}$ in the mass range 350-550 GeV decaying to a few ${\ensuremath{\pi}}_{T}{\ensuremath{\pi}}_{T}$ combinations; (B) ${\ensuremath{\rho}}_{\overline{D}D}$ with a mass of 375-425 GeV and ${\ensuremath{\rho}}_{\overline{U}U}$ in the mass range 500-700 GeV both decaying to a few ${\ensuremath{\pi}}_{T}{\ensuremath{\pi}}_{T}$ modes. The ${\ensuremath{\rho}}_{\overline{D}D}\ensuremath{\rightarrow}\mathrm{dijet}$ signal of case A is large at all colliders and can be sought now at the Tevatron. The ${\ensuremath{\pi}}_{T}{\ensuremath{\pi}}_{T}$ production rates in both cases are of \ensuremath{\sim}10 pb at the Tevatron and \ensuremath{\sim}10 nb at the Superconducting Super Collider (SSC). The technipions can be sought in the next high-luminosity run of the Tevatron and may be excludable if backgrounds are not too severe. Experiments at the SSC certainly should be able to determine whether they exist.

Nonperturbative fragmentation of the top quark.

By the use of a simple phenomenological string model, the energy lost by the top quark through nonperturbative fragmentation effects before its weak decay is computed. This energy lost is in first approximation proportional to the rate between the decay time and the hadronization time of the top as measured in the center-of-mass frame of the top and its color partner. Precise computations of the energy lost by the top in terms of its mass when produced in colliders such as the Fermilab Tevatron, CERN Large Hadron Collider, Superconducting Super Collider, and CERN Linear Collider are presented. As expected, this effect decreases quickly with the top mass but it could be relevant for a top mass below 100 GeV.

Single-forward-jet tagging and central-jet vetoing to identify the leptonic WW decay mode of a heavy Higgs boson.

We study the extraction of the heavy-Higgs-boson signal $H\ensuremath{\rightarrow}{W}^{+}{W}^{\ensuremath{-}}\ensuremath{\rightarrow}\overline{\ensuremath{\ell}}\ensuremath{\nu}, \ensuremath{\ell}\overline{\ensuremath{\nu}}$ ($\ensuremath{\ell}=e or \ensuremath{\mu}$) from the standard-model background at hadron supercolliders. By tagging a single forward jet with energy ${E}_{j}&gt;3$ TeV and pseudorapidity $3&lt;|{\ensuremath{\eta}}_{j}|&lt;5$ and by vetoing central jets of transverse momenta ${p}_{\mathrm{Tj}}&gt;60$ GeV in the pseudorapidity range $0&lt;|{\ensuremath{\eta}}_{j}|&lt;3$, the QCD $\mathrm{WWj}$ and $t\overline{t}j\ensuremath{\rightarrow}\mathrm{WWb}\overline{b}j$ backgrounds are suppressed. For ${m}_{H}=1$ TeV there are about 46 signal events from electroweak-vector-boson scattering (of which 36 events are of Higgs-boson origin) at the Superconducting Super Collider (SSC) for an integrated luminosity of 10 ${\mathrm{fb}}^{\ensuremath{-}1}$ and 10 other events from the $\mathrm{WWj}$ and $t\overline{t}j$ backgrounds for ${m}_{t}=140$ GeV. The experimental separation of the vector-boson-scattering subprocess is thereby possible. At the CERN Large Hadron Collider, with an ${E}_{j}&gt;2$ TeV jet energy cut, all cross sections are about a factor of 10 below the SSC values.

Risk Perception Mapping: Using Ethnography to Define the Locally Affected Population for a Low‐Level Radioactive Waste Storage Facility in Michigan

The concept of a “risk perception shadow” (RPS) has been suggested to describe the geocultural area in which a locally affected population perceives itself to be at risk from a proposed project. Generally such projects involve potentially dangerous substances or activities. The initial conceptualization of an RPS was developed during the social assessment of a proposed Superconducting Super Collider (SSC) in Michigan. This article describes an effort at mapping and analyzing an RPS produced by a proposal to site a low‐level radioactive waste (LLRW) storage facility in Michigan. A unique sampling technique was used to define the boundary of the generally concentric RPS. Risk perception mapping (RPM) is suggested as a rapid and efficient method for defining locally affected populations for social impact studies.

Senate passes energy, water appropriations bill

The $21.98 billion energy and water appropriations bill (HR 2427) was passed by the full Senate on July 10, representing an increase of about $1 billion over FY 1991 funding. With a 96‐3 vote, HR 2427 was one of the first of 13 spending bills to be approved by the Senate. (See “DOE Funding Up in FY 1991,” Eos, July 16.)The Senate appropriated $509 million to begin construction of the controversial Superconducting Super Collider (SSC) in Waxahachie, Texas. Earlier this year, the House voted $434 million for the project, which was $100 million less than requested by the administration.

Observability of a heavy Higgs boson at hadron supercolliders.

We present a coherent analysis of Higgs-boson production in the channels $\mathrm{pp}\ensuremath{\rightarrow}\mathrm{ZZX}\ensuremath{\rightarrow}{l}^{+}{l}^{\ensuremath{-}}{l}^{\ensuremath{'}+}{l}^{\ensuremath{'}\ensuremath{-}}X(l, {l}^{\ensuremath{'}}=e, \ensuremath{\mu})$ and $\mathrm{pp}\ensuremath{\rightarrow}\mathrm{ZZX}\ensuremath{\rightarrow}{l}^{+}{l}^{\ensuremath{-}}\ensuremath{\nu}\overline{\ensuremath{\nu}}X(\ensuremath{\nu}={\ensuremath{\nu}}_{e}, {\ensuremath{\nu}}_{\ensuremath{\mu}}, {\ensuremath{\nu}}_{\ensuremath{\tau}})$ for ${m}_{H}\ensuremath{\ge}600$ GeV at hadron supercolliders, using the exact matrix elements for $\mathrm{gg}\ensuremath{\rightarrow}\mathrm{ZZ}$ and $\mathrm{qq}\ensuremath{\rightarrow}\mathrm{qqZZ}$. The importance of a complete understanding of the shape of the perturbative $\mathrm{pp}\ensuremath{\rightarrow}\mathrm{ZZX}$ background from nonresonant diagrams is emphasized. We find that for the CERN Large Hadron Collider (LHC) to have a Higgs-boson discovery potential comparable to that of the Superconducting Super Collider (SSC) requires at least a factor of 10 times more integrated luminosity. In particular, assuming an integrated luminosity of ${10}^{4}$ ${\mathrm{pb}}^{\ensuremath{-}1}$ and perfect lepton identification efficiency, the LHC (SSC) can identify Higgs bosons as resonances with mass up to 600 (800) GeV in $\mathrm{pp}\ensuremath{\rightarrow}\mathrm{ZZX}\ensuremath{\rightarrow}{l}^{+}{l}^{\ensuremath{-}}{l}^{\ensuremath{'}+}{l}^{\ensuremath{'}\ensuremath{-}}X$. To extend the discovery range of the LHC to ${m}_{H}=800$ GeV in this channel requires an integrated luminosity of at least ${10}^{5}$ ${\mathrm{pb}}^{\ensuremath{-}1}$. For ${m}_{H}&gt;800$ GeV, a clear resonance structure is missing; however, one can still discriminate between a heavy Higgs boson with ${m}_{H}\ensuremath{\sim}1$ TeV and a light Higgs boson (${m}_{H}\ensuremath{\lesssim}2{M}_{z}$) at the SSC.

Decay versus hadronization for top quarks produced in hadron colliders.

Decay and hadronization time scales are compared for top quarks produced in hadron colliders. It is assumed that long-distance effects associated with hadronization appear when two color sources in a singlet state reach a separation of order 1 fm in their center of mass. A condition is obtained for hadronization to occur before decay, taking into account the color structure and kinematics of the hadronic production process. The condition is incorporated into a calculation of the production cross section to obtain probabilities for hadronization before decay as functions of top mass and momentum. Results are presented for $\overline{p}p$ collisions at $\sqrt{s}=1.8$ TeV (Fermilab Tevatron) and for $\mathrm{pp}$ collisions at $\sqrt{s}=40$ TeV [Superconducting Super Collider (SSC)]. It is found that hadronization is not likely to be important at the Tevatron for ${m}_{t}\ensuremath{\gtrsim}150$ GeV, but may persist to higher masses at SSC energies.

Associated production of Higgs bosons with tt-bar pairs.

Associated production of Higgs bosons with top-antitop pairs at hadron colliders, pp\ensuremath{\rightarrow}Htt\ifmmode\bar\else\textasciimacron\fi{}X, is examined. By tagging on an isolated secondary lepton, e or \ensuremath{\mu}, from the t or t\ifmmode\bar\else\textasciimacron\fi{} decay, discovery of an intermediate-mass Higgs boson, ${\mathit{m}}_{\mathit{H}}$\ensuremath{\simeq}80--150 GeV, via H\ensuremath{\rightarrow}\ensuremath{\gamma}\ensuremath{\gamma} is rendered feasible at the Superconducting Super Collider (SSC) (\ensuremath{\surd}s =40 TeV). Allowing a factor-of-0.4 signal reduction for isolation cuts and selection efficiencies leaves about 21 events per SSC year for ${\mathit{m}}_{\mathit{H}}$\ensuremath{\simeq}80--130 GeV, and somewhat less for 130--150 GeV, above an anticipated small background. At the CERN Large Hadron Collider (\ensuremath{\surd}s =16 TeV), the cross section is reduced by about a factor of 1/8.

Photon stimulated desorption from aluminum and stainless steel

Photon stimulated desorption of neutral species (PSD) is the major dynamic gas load in electron synchrotron light source. In the National Synchrotron Light Source, (NSLS) PSD presented initial machine commissioning difficulty. Sensitivity to surface contamination on PSD has been experienced during an incident of Fomblin Oil contamination.1 U10B‐photon stimulated desorption experimental station is constructed to investigate: 1—the degree of the contribution to the photon stimulated desorption (PSD) from primary photon flux and scattered secondary photon flux, 2—the underlying mechanism for photon stimulated desorption, 3—criteria to chose the proper beam tube material for future accelerators such as SXLS, FEL, superconducting super collider (SSC), ALS... . In this report, only photon stimulated desorption of neutral species (PSD) from stainless steel and aluminum is reported.

Monolithic, radiation hard charge sensitive preamplifier using diffused N-channel junction field effect transistors

A monolithic preamplifier entirely based on epitaxial channel, diffused-gate N-JFET has been designed and thoroughly investigated by means of SPICE simulation and breadboard implementation. Performance, tolerances, and matching of the devices are remarkably good, and the excess noise can be reduced in future runs. A preamplifier has been wired using monolithic JFET and is working according to predictions. The preamplifier is intended for applications with ionization chamber calorimeters in the SSC (Superconducting Super Collider) environment at processing times of about 50 ns.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>