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Quantum Suppression of beamstrahlung for future e+e- linear collider: an evaluation of QED backgrounds

Description: Beamstrahlung at interaction point may present severe limitations on linear collider performance. The approach to reduce this effect adopted for all current designs at 0.5 TeV range in center-of-mass energy will become more difficult and less effective at higher energy. We discuss the feasibility of an alternative approach, based on an effect known as quantum suppression of beamstrahlung, for future linear colliders at multi-TeV energy.
Date: October 13, 1998
Creator: Xie, Ming
Partner: UNT Libraries Government Documents Department

Searches for exotic particles at the Tevatron

Description: This paper reports on recent searches for exotic particles by the CDF and D#31; Collaborations. The results are derived from the data collected during the 1992-95 Run I at the Fermilab Tevatron. Limits are presented on new heavy gauge bosons, leptoquarks, monopoles and technicolor particles.
Date: October 1, 1998
Creator: Grosso-Pilcher, C.
Partner: UNT Libraries Government Documents Department

RF power sources for 5--15 TeV linear colliders

Description: After outlining the design of the NLC rf system at 1 TeV, the possibility of a leap in linear collider energy into the 5--15 TeV energy range is considered. To keep the active accelerator length and ac wall-plug power within reasonable bounds, higher accelerating gradients at higher rf frequencies will be necessary. Scaling relations are developed for basic rf system parameters as a function of frequency, and some specific parameter examples are given for colliders at 34 Ghz and 91 Ghz. Concepts for rf pulse compression system design and for high power microwave sources at 34 Ghz (for example sheet-beam and multiple-beam klystrons) are briefly discussed.
Date: September 1, 1996
Creator: Wilson, P.B.
Partner: UNT Libraries Government Documents Department

Discussion on muon collider parameters at center of mass energies from 0.1 TeV to 100 TeV

Description: The main motivation for research and development efforts on muon collider technology is the assertion that affordably priced muon colliders might provide lepton-lepton collisions at much higher center of mass (CoM) energies than is feasible for electron colliders, and perhaps eventually explore the spectrum of elementary particles at mass scales inaccessible even to hadron colliders. This paper attempts to present some justification for these assertions through discussion and evaluation of the self-consistent muon collider parameter sets given in table 1 at CoM energies ranging from 0.1 to 100 TeV. The parameter set at 0.1 TeV CoM energy was included as a lower energy reference point and was constrained to essentially reproduce one of the sets of parameters currently under study by the Muon Collider Collaboration (MCC). In contrast, the other parameter sets represent speculation by the author on how the parameters might evolve with CoM energy and they have not been studied or discussed in detail within the MCC.
Date: June 1, 1998
Creator: King, B.J.
Partner: UNT Libraries Government Documents Department

Very large hadron collider (VLHC)

Description: A VLHC informal study group started to come together at Fermilab in the fall of 1995 and at the 1996 Snowmass Study the parameters of this machine took form. The VLHC as now conceived would be a 100 TeV hadron collider. It would use the Fermilab Main Injector (now nearing completion) to inject protons at 150 GeV into a new 3 TeV Booster and then into a superconducting pp collider ring producing 100 TeV c.m. interactions. A luminosity of {approximately}10{sup 34} cm{sup -2}s{sup -1} is planned. Our plans were presented to the Subpanel on the Planning for the Future of US High- Energy Physics (the successor to the Drell committee) and in February 1998 their report stated ``The Subpanel recommends an expanded program of R&D on cost reduction strategies, enabling technologies, and accelerator physics issues for a VLHC. These efforts should be coordinated across laboratory and university groups with the aim of identifying design concepts for an economically and technically viable facility`` The coordination has been started with the inclusion of physicists from Brookhaven National Laboratory (BNL), Lawrence Berkeley National Laboratory (LBNL), and Cornell University. Clearly, this collaboration must expanded internationally as well as nationally. The phrase ``economically and technically viable facility`` presents the real challenge.
Date: September 1, 1998
Partner: UNT Libraries Government Documents Department

Muon Colliders: New Prospects for Precision Physics and the High Energy Frontier

Description: An overview is given of muon collider technology and of the current status of the muon collider research program. The exciting potential of muon colliders for both neutrino physics and collider physics studies is then described and illustrated using self-consistent collider parameter sets at 0.1 TeV to 100 TeV center-of-mass energies.
Date: June 1998
Creator: King, B. J.
Partner: UNT Libraries Government Documents Department

Future accelerators using micro-fabrication technology

Description: Historically, each generation of new accelerators has produced a thousand-fold increase over their predecessors. Thus, the d.c. accelerators were surpassed by weak focusing cyclotrons and synchrotrons. Then strong focusing machines surpassed the weak focusing ones, and now we are in the process of designing machines for 10 to 20 TeV. This paper is devoted to the study of the next generation of accelerators which we can contemplate will be in the range of 1000 TeV. The radiation loss in a circular machine would correspond to approximately 20 TeV/turn. It is clear then that the future generation of accelerators will have to be linear accelerators. Furthermore, since the center of mass energy of a 1000 TeV machine is only approximately 1.5 TeV, these linacs will be built in pairs and operated primarily as linear colliders. This meas that the average beam power in one of the devices will be quite large. This in turn leads us toward high efficiency acceleration schemes, capable of high repetition rates. The poor efficiency of laser accelerators and other exotic proposals make them poor candidates for a future generation collider.
Date: January 1, 1983
Creator: Maschke, A.W.
Partner: UNT Libraries Government Documents Department

Excitation Curves of small quadrupoles for tev I Beam Line Use

Description: Excitation curves for at least one magnet of each length of TeV I Small Quadrupole have been measured utilizing the MIF-TeV I VAX standard measurement system. Since the standard measurement sequence does not include this sort of excitation curve, the standard reports issued on the magnet does not contain this data. Measurements were taken with the gradient probe SQ25 (probe ID No.40) centered in the aperture and extending through the field length to integrate the strength of the magnet. The parameter BETA2 reported below is the probe calibration factor for this probe in meters**2. The gradient strength of the magnet in Tesla-meters/meter is obtained from the measured flux by dividing by BETA2. The data were collected from MEAS BASE runs in which the measurement probe flux is recorded in a baseline measurement sequence. The hysteresis of the magnet is set by ramping to the specified maximum current then back to zero. The integrator is zeroed at zero current and the integrator voltage recorded one or more times. The current is then ramped successively to the measurement current where the integrator voltage is recorded, to full field and back to zero where the integrator voltage is again recorded for each current at which data is desired. After correction for drift, amplifier gain and integrator Re, the data is recorded in the Reduced data files. This report collects this data for measurements on several magnets. The data at non-zero currents are converted to Tesla and reported also in Tesla/Amp. In order to prepare the report entirely with the DATATRIEVE query language, the usual averaging of Probe Up and Probe Down measurements was not carried out. The reader is invited instead to look at both sets of data to observe that the error to be canceled is small. In addition, this report may ...
Date: February 1, 1985
Creator: Brown, B.
Partner: UNT Libraries Government Documents Department

Proposal for a Non-Interceptive Spatio-Temporal Correlation Monitor

Description: Designs toward TeV-range electron-positron linear colliders include a non-zero crossing angle colliding scheme at the interaction point to mitigate instabilities and possible background. Maximizing the luminosity when operating with non-zero crossing angles requires the use of 'crab' cavities to impart a well-defined spatio-temporal correlation. In this paper we propose a novel noninterceptive diagnostic capable of measuring and monitoring the spatio-temporal correlation, i.e. the transverse position of sub-picosecond time slices, within bunch. An analysis of the proposed scheme, its spatio-temporal resolution and its limitations are quantified. Finally, the design of a proof-of-principle experiment in preparation for the Fermilab's A0 photoinjector is presented.
Date: May 1, 2009
Creator: Maxwell, T. & Piot, P.
Partner: UNT Libraries Government Documents Department

Constraints on q{bar q}{gamma}{gamma} contact interactions at future hadron colliders

Description: The author explores the capability of the Tevatron and LHC as well as other future hadron colliders to place limits on the possible existence of flavor-independent q{bar q}{gamma}{gamma} contact interactions which can lead to an excess of high p{sub t} diphoton events with large invariant masses. Constraints on the corresponding e{sup +}e{sup {minus}}{gamma}{gamma} contact interaction already exist from LEP. In the case of hadron colliders, strong constraints on the scale associated with such interactions are achievable in all cases, e.g., of order 0.9(3) TeV at TeV33(LHC).
Date: September 1, 1996
Creator: Rizzo, T.G.
Partner: UNT Libraries Government Documents Department

2 x 2 TeV mu(superscript +) mu (superscript) collider

Description: The scenarios for high-luminosity 2 x 2 TeV and 250 x 250 GeV {mu}{sup +}{mu}{sup -} colliders are presented. Having a high physics potential, such a machine has specific physics and technical advantages and disadvantages when compared with an e{sup +}e{sup -} collider. Parameters for the candidate designs and the basic components - proton source, pion production and decay channel, cooling, acceleration and collider storage ring - are considered. Attention is paid to the areas mostly affecting the collider performance: targetry, energy spread, superconducting magnet survival, detector backgrounds, polarization, environmental issues. 13 refs., 9 figs., 4 tabs.
Date: October 1, 1996
Creator: Mokhov, N.V. & Noble, R.J.
Partner: UNT Libraries Government Documents Department

Hadronic spectra from collisions of heavy nuclei

Description: Hadronic spectra from collisions of heavy ions at ultrarelativistic energies are discussed, concentrating on recent measurements at the SPS of central Pb+Pb collisions at 158 GeV/nucleon, which are compared to collisions of lighter ions and at lower beam energies. Baryon stopping is seen to be larger for heavier systems and lower energies. Total yields of pions and kaons scale with the number of participants in central collisions at the SPS; in particular, the K/{pi} ratio is constant between central S+S and Pb+Pb at the SPS. Transverse mass spectra indicate significantly larger radial flow for the heavier systems. At midrapidity, an enhancement of <{pi}{sup {minus}}>/<{pi}{sup +}> and <K{sup {minus}}>/<K{sup +}> at low P{sub T} are best explained by final state Coulomb interaction with the residual charge of the fireball.
Date: March 1, 1997
Creator: Jacobs, P.
Partner: UNT Libraries Government Documents Department

Scaling linear colliders to 5 TeV and above

Description: Detailed designs exist at present for linear colliders in the 0.5-1.0 TeV center-of-mass energy range. For linear colliders driven by discrete rf sources (klystrons), the rf operating frequencies range from 1.3 GHz to 14 GHz, and the unloaded accelerating gradients from 21 MV/m to 100 MV/m. Except for the collider design at 1.3 GHz (TESLA) which uses superconducting accelerating structures, the accelerating gradients vary roughly linearly with the rf frequency. This correlation between gradient and frequency follows from the necessity to keep the ac {open_quotes}wall plug{close_quotes} power within reasonable bounds. For linear colliders at energies of 5 TeV and above, even higher accelerating gradients and rf operating frequencies will be required if both the total machine length and ac power are to be kept within reasonable limits. An rf system for a 5 TeV collider operating at 34 GHz is outlined, and it is shown that there are reasonable candidates for microwave tube sources which, together with rf pulse compression, are capable of supplying the required rf power. Some possibilities for a 15 TeV collider at 91 GHz are briefly discussed.
Date: April 1, 1997
Creator: Wilson, P.B.
Partner: UNT Libraries Government Documents Department


Description: A focal point for the HEMC'99 workshop was the evaluation of straw-man parameter sets for the acceleration and collider rings of muon colliders at center of mass energies of 10 TeV and 100 TeV. These self-consistent parameter sets are presented and discussed. The methods and assumptions used in their generation are described and motivations are given for the specific choices of parameter values. The assessment of the parameter sets during the workshop is then reviewed and the implications for the feasibility of many-TeV muon colliders are evaluated. Finally, a preview is given of plans for iterating on the parameter sets and, more generally, for future feasibility studies on many-TeV muon colliders.
Date: May 5, 2000
Creator: KING,B.J.
Partner: UNT Libraries Government Documents Department

Measurement of the mass of the B{sub s}{sup 0} meson in {bar p}p collisions at {radical}s = 1.8 TeV

Description: We measure the mass of the B{sub s}{sup 0} meson by fully reconstructing the decay B{sub s}{sup 0} {yields} J/{psi} {phi} with the subsequent decays J/{psi} {yields} {mu}{sup +} {mu}{sup {minus}} and {phi} {yields} K{sup +} K{sup {minus}}. The data was obtained from 19.3 pb{sup {minus}1} of integrated luminosity of {bar p}p collisions at {radical}s = 1.8 TeV using the Collider Detector at Fermilab (CDF). A sample of 80,000 inclusive J/{psi} {yields} {mu}{sup +}{mu}{sup {minus}} events is used to study systematic biases in track reconstruction and is used to calibrate the momentum scale. We reconstruct the kinematically similar decays B{sup {minus}} {yields} J/{psi} K{sup {minus}} and B{sup 0} {yields} J/{psi} K* to study the mass measurement technique used for the B{sup 0} meson. Based on the observation of 32 {plus_minus} 6 candidates, the mass of the B{sub s}{sup 0} meson is measured to be 5369.9 {plus_minus} 2.3 {plus_minus} 1.3 MeV/c{sup 2}.
Date: July 1995
Creator: Abe, F.
Partner: UNT Libraries Government Documents Department

Top quark physics at the D0 experiment

Description: In this paper I present the latest results on top quark physics from the D0 collaboration since the discovery of the top quark in March 1995. I summarize the discovery results, discuss progress since the discovery, and show how we can measure the top quark mass using three separate techniques. The measurements were made at the Fermilab Tevatron, a p{bar p} collider with {radical}s = TeV, using {approximately}50 pb{sup {minus}1} data collected from 1992 to early 1995.
Date: January 1, 1996
Creator: Heinson, A.P.
Partner: UNT Libraries Government Documents Department

MARS code developments

Description: Recent developments in the physical model of 1 MeV to 100 TeV hadron and lepton interactions with nuclei and atoms are described. These include a new nuclear cross section library, a model for soft pion production, the cascade-exciton model, the dual parton model, deuteron-nucleus and neutrino-nucleus interaction models, detailed description of mu, pi and anti p absorption and a unified treatment of muon and charged hadron electromagnetic interactions with matter. New algorithms are implemented into the MARS13(98) Monte Carlo code and benchmarked against experimental data. The code capabilities to simulate cascades and generate a variety of results in complex media have been also enhanced.
Date: December 1, 1998
Creator: N.V.Mokhov, S.I.Striganov, A.Van Ginneken, S.G.Mashnik, A.J.Sierk and J.Ranft
Partner: UNT Libraries Government Documents Department

Studies of the top quark with the D0 detector

Description: The observation of the top quark by the D0 experiment, at Fermilab`s Tevatron proton-antiproton collider, is briefly reviewed. The analysis of the top quark mass in the lepton plus jets decay channels, resulting in m{sub t} {approx} 200 GeV/c{sup 2} is reviewed; and a preliminary mass analysis from the dilepton decay channels resulting in m{sub t} = 145 {plus_minus} 25 (statistical) {plus_minus} 20 (systematic) GeV/c{sup 2} is presented. These mass measurements are compared with Standard Model limits from CERN`s LEP experiments and the published CDF measurement. Preliminary observation of top quark-W boson correlation is shown.
Date: January 1, 1996
Creator: Stephens, R.W.
Partner: UNT Libraries Government Documents Department

The search for squarks, gluinos and stop squarks in D0

Description: Searches through data collected by D0 at Fermilab during the 1992-- 1993 p {bar p} collider run for the supersymmetric partners to the quark and the gluon, the squark and gluino, including a low mass scalar top squark, are reviewed. A set of classic searches were conducted for missing E{sub T} plus jets signatures. No evidence of positive signals is reported, but limits are set on the squark and gluino masses.
Date: August 1, 1995
Creator: Claes, D.
Partner: UNT Libraries Government Documents Department

Studies of topological distributions of the three- and four-jet events in {bar p}p collisions at {radical}s = 1800 GeV with the D0 detector

Description: The global topologies of three- and four-jet events produced in {bar p}p interactions are described. the three- and four-jet events are selected from data recorded by the D0 detector at the Tevatron Collider operating at a center-of-mass energy of {radical}s = 1800 GeV. the measured normalized distributions of various topological variables are compared with parton-level predictions of the tree- level QCD calculations. The parton-level QCD calculations are found to be in good agreement with the data. The studies also show that the topological distributions of the different subprocesses involving different numbers of quarks are very similar and reproduce the measured distributions well.
Date: July 1, 1995
Creator: Abachi, S.
Partner: UNT Libraries Government Documents Department

Electrons Emitted from 33-TeV Pb Ions During Penetratiaon of Solids

Description: At ultrarelativistic energies, ionization cross sections exceed electron capture cross sections by several orders of magnitude (1,2). Effectively, all electrons transferred to a highly relativistic heavy ion moving in a solid or gaseous target medium are stripped in a relatively short distance. Above ~20 GeV/nucleon, the principal mechanism for electron capture is from pair production (ECPP) (2). The total cross sections for ECPP are te&nically important for making reliable predictions of operating limitations for relativistic heavy-ion colliders, e.g., RHIC and LHC (3). In ECPP, it is expected that ~30% of capture proceeds to excited states of the capturing ion. Some of these relatively weakly bound electrons are radiatively long-lived and easily lost in secondary collisions in solid targets, making measurements of their contributions to total capture experimentally difficult. Electrons lost from high-energy ions in collisions with target atoms form a cusp-shaped spectral peak in the forward direction in the laboratory frame centered at the velocity of the moving ion (4-5). The shape of this electron loss to projectile continuum (ELC) peak has been shown (5,6) to depend on the initial atomic bound state from which the electron is ionized. We have measured and compared ELC electrons from direct ionization of hydrogenlike 33-TeV Pb<sup>81+</sup>(ls) ions (Lorentz factory <font face="symbol">g</font> = 168) in Al with similar data for electrons created by ECPP for bare Pb<sup>82+</sup> ions in Au - followed by ionization. Both measured ELC peaks are narrow in momentum and angle and very similar in shape.
Date: July 22, 1999
Creator: Datz, S.; Grafstroem, P.; Knudsen, H.; Krause, H.F.; Mikkelsen, U.; Moeller, S. et al.
Partner: UNT Libraries Government Documents Department