NEUTRINO SCATTERING IN PERTURBATIVE QCD AND IMPLICATIONS FOR THE WEINBERG ANGLE. (open access)

NEUTRINO SCATTERING IN PERTURBATIVE QCD AND IMPLICATIONS FOR THE WEINBERG ANGLE.

We summarize a recent calculation of perturbative neutrino cross sections that includes NLO and mass corrections. We provide numerical results for quantities that are related to the extraction of the weak mixing angle from neutrino deep inelastic scattering.
Date: May 19, 2003
Creator: KRETZER,S. HALL-RENO,M.
System: The UNT Digital Library
Recent improvements to the ASTRA particle tracking code (open access)

Recent improvements to the ASTRA particle tracking code

The Astra simulation code has been successfully used in the design of linac and rf photoinjector systems utilizing beams with azimuthal symmetry. We present recently implemented changes to Astra that allow tracking of beams in beamlines without the assumption of any symmetry. The changes especially include a 3D mesh space charge algorithm and the possibility to import 3D electromagnetic fieldmaps from eigensolver programs.
Date: May 19, 2003
Creator: Flottmann, Klaus; Lidia, Steven & Piot, Philippe
System: The UNT Digital Library
Emittance compensation studies of photoinjector beams with angular momentum (open access)

Emittance compensation studies of photoinjector beams with angular momentum

Beam dynamics studies on the FNPL photo injector that seek to optimize the transport of intense electron beams with large values of canonical angular momentum have been performed. These studies investigate the effect of solenoid emittance compensation on beams that evolve under the combined influence of intense space charge forces and large angular momentum. We present details of experimental measurements and supporting simulations of beam envelope evolution.
Date: May 19, 2003
Creator: Lidia, Steven
System: The UNT Digital Library
Hera Beam Tail Shaping by Tune Modulation. (open access)

Hera Beam Tail Shaping by Tune Modulation.

To study CP violation, the HEM-B experiment uses an internal wire target in the transverse halo of the stored HERA proton beam. Operational experience shows that the resulting interaction rates are extremely sensitive to tiny orbit jitter amplitudes. Various methods have been studied to stabilize these interaction rates by increasing diffusion in the transverse proton beam tails without affecting the luminosity at the electron-proton collider experiments ZEUS and H1. Tune modulation was found to be a promising method for this task. Experiments performed in recent years will be reported.
Date: May 19, 2003
Creator: Montag, C.
System: The UNT Digital Library
Lithium-Based Electrochromic Mirrors (open access)

Lithium-Based Electrochromic Mirrors

Antimony, antimony-copper, and antimony-silver thin films were prepared by DC magnetron sputtering on glass substrates. Their reflectance and transmittance in the visible range were measured before and after electrochemical lithiation. The mixed metal films exhibited larger changes in reflectance and small shifts in the optical absorption edge compared with pure antimony films. Electrochromic cycling speed and stability of the Sb-Li system were improved by the addition of copper and silver.
Date: May 19, 2003
Creator: Richardson, Thomas J. & Slack, Jonathan L.
System: The UNT Digital Library
Effective theory approach to unstable particles (open access)

Effective theory approach to unstable particles

The authors present a novel treatment of resonant massive particles appearing as intermediate states in high energy collisions. The approach uses effective field theory methods to treat consistently the instability of the intermediate resonant state. As a result gauge invariance is respected in every step and calculations can in principle be extended to all orders in perturbation theory, the only practical limitation in going to higher orders being the standard difficulties related to multi-loop integrals. The authors believe that the longstanding problem related to the treatment of instability of particles is now solved.
Date: May 19, 2003
Creator: Zanderighi, Giulia
System: The UNT Digital Library
An injector for the proposed Berkeley Ultrafast X-Ray Light Source (open access)

An injector for the proposed Berkeley Ultrafast X-Ray Light Source

Berkeley Lab has proposed to build a recirculating linac based X-ray source for ultra-fast dynamic studies [1]. This machine requires a flat electron beam with a small vertical emittance and large x/y emittance ratio to allow for compression of spontaneous undulator emission of soft and hard x-ray pulses, and a low-emittance, round electron beam for coherent emission of soft x-rays via the FEL process based on cascaded harmonic generation [2]. We propose an injector system consisting of two high gradient high repetition rate photo cathode guns [3] (one for each application), an {approx}120 MeV super conducting linear accelerator, a 3rd harmonic cavity for linearization of the longitudinal phase space, and a bunch compressor. We present details of the design and the results of particle tracking studies using several computer codes.
Date: May 19, 2003
Creator: Lidia, Steven; Corlett, John; Pusina, Jan; Staples, John & Zholents, Alexander
System: The UNT Digital Library
COLLIMATION EXPERIENCE AT RHIC. (open access)

COLLIMATION EXPERIENCE AT RHIC.

In the Relativistic Heavy Ion Collider (RHIC) the abort kicker magnets are the limiting aperture. Continuous losses at this location could deteriorate the kicker performance. In addition, losses especially in the triplet area cause backgrounds in the experimental detectors. The RHIC one-stage collimation system was used to reduce these backgrounds as well as losses at the abort kickers. Collimation performance and results from various runs with even and uneven species (Au-Au, pp and d-Au) are presented and compared. Upgrades of the system for the upcoming high luminosity runs are outlined.
Date: May 19, 2003
Creator: DREES,K. A. FLILLER,R. TRBOJEVIC,D. KAIN,V.
System: The UNT Digital Library
FRAGMENTATION FUNCTIONS AND IMPLICATIONS FOR SPIN PHYSICS. (open access)

FRAGMENTATION FUNCTIONS AND IMPLICATIONS FOR SPIN PHYSICS.

The present status of fragmentation function (FF) analysis is summarized and the role of FFs in QCD hard scattering phenomenology is outlined with emphasis on spin physics.
Date: May 19, 2003
Creator: KRETZER,S.
System: The UNT Digital Library
TUNE MODULATION FROM BEAM BEAM INTERACTION AND UNEQUAL RADIO FREQUENCIES IN RHIC. (open access)

TUNE MODULATION FROM BEAM BEAM INTERACTION AND UNEQUAL RADIO FREQUENCIES IN RHIC.

The two RHIC rings have independent rf systems to accommodate different species. Thus, the radio frequencies can differ when the phase and radial loops are closed, and the if frequencies of the two rings are not synchronized. A radio frequency difference leads to longitudinally moving beam crossing points. When the crossing points are between the beam splitting dipoles, the beams experience the beam-beam interaction. Outside the interaction region the beam-beam interaction is switched off. In this way the tune is modulated. A computation of the tune modulation depth, pulse shape and frequency is presented. Tune modulation measurements are shown.
Date: May 19, 2003
Creator: FISCHER,W. CAMERON,P. PEGGS,S. SATOGATA,T.
System: The UNT Digital Library
Symmetric Textures in So(10) and LMA Solution for Solar Neutrinos. (open access)

Symmetric Textures in So(10) and LMA Solution for Solar Neutrinos.

A model based on SUSY SO(10) combined with SU(2) family symmetry is constructed. In contrast with the commonly used effective operator approach, 126-dimensional Higgs fields are utilized to construct the Yukawa sector. R-parity symmetry is thus preserved at low energies. The symmetric mass textures arising from the left-light symmetry breaking chain of SO(10) give rise to very good predictions for quark and lepton masses and mixings. The prediction for sin2{beta} agrees with the average of current bounds from BaBar and Belle. In the neutrino sector, our predictions are in good agreement with results from atmospheric neutrino experiments. Our model accommodates the LMA solution to the solar neutrino anomaly. The prediction of our model for the |U{sub ev{sub 3}}| element in the MNS matrix is close to the sensitivity of current experiments; thus the validity of our model can be tested in the near future. We also investigate the coil-elation between the |U{sub ev{sub 3}}| element and tan{sup 2} {theta}{sub {center_dot}}, in a general two-zero neutrino mass texture.
Date: May 19, 2003
Creator: Chen, Mu-Chun & Mahanthappa, K. T.
System: The UNT Digital Library
PARTICLE PRODUCTION AT RHIC ENERGIES. (open access)

PARTICLE PRODUCTION AT RHIC ENERGIES.

This paper presents recent results from the BRAHMS experiment at RHIC; including results on particle production in rapidity space extending from y = 0 to y {approx} 3 and on the transverse momentum distribution of fully identified charged particles. These results were obtained from the 5% most central Au-Au collisions recorded during RHIC Run-2 at {radical}(s{sub NN}) = 200 GeV.
Date: May 19, 2003
Creator: DEBBE,R. FOR THE BRAHMS COLLABORATION
System: The UNT Digital Library
BEAM-BEAM 2003 SUMMARY. (open access)

BEAM-BEAM 2003 SUMMARY.

This paper summarizes the presentations and discussions of the Beam-Beam'03 workshop, held in Montauk, Long Island, from May 19 to 23, 2003. Presentations and discussions focused on halo generation from beam-beam interactions; beam-beam limits, especially coherent limits and their effects on existing and future hadron colliders; beam-beam compensation techniques, particularly for long-range interactions; and beam-beam study tools in theory, simulation, and experiment.
Date: May 19, 2003
Creator: FISCHER,W. SEN,T.
System: The UNT Digital Library
LUMINOSITY INCREASE AT THE INCOHERENT BEAM BEAM LIMIT WITH SIX SUPERBUNCHES IN RHIC. (open access)

LUMINOSITY INCREASE AT THE INCOHERENT BEAM BEAM LIMIT WITH SIX SUPERBUNCHES IN RHIC.

By colliding bunches of greater length under a larger angle, the tune spread caused by the beam-beam interaction can be reduced. Assuming a constant limit for the beam-beam tune shift, the bunch intensity can then be raised. In this way, a luminosity increase is possible. We review this strategy for proton beams in RHIC, with two collisions and consider six long bunches. Barrier cavities are used to fill every accelerating bucket of the machine, except for an abort gap, and to create the superbunches bunches at store. Resonances driven by the beam-beam interaction and coherent effects are neglected in this article.
Date: May 19, 2003
Creator: FISCHER,W. BLASKIEWICZ,M.
System: The UNT Digital Library
Summary of Beam Beam Observations During Stores in Rhic. (open access)

Summary of Beam Beam Observations During Stores in Rhic.

During stores, the beam-beam interaction has a significant impact on the beam and luminosity lifetimes in RHIC. This was observed in heavy ion, and even more pronounced in proton collisions. Observations include measurements of beam-beam induced tune shifts, lifetime and emittance growth measurements with and without beam-beam interaction, and background rates as a function of tunes. In addition, RHIC is currently the only hadron collider in which strong-strong beam-beam effects can be seen. Coherent beam-beam modes were observed, and suppressed by tune changes. In this article we summarize the most important beam-beam observations made during stores so far.
Date: May 19, 2003
Creator: Fischer, W.
System: The UNT Digital Library
Self-consistency and coherent effects in nonlinear resonances (open access)

Self-consistency and coherent effects in nonlinear resonances

The influence of space charge on emittance growth is studied in simulations of a coasting beam exposed to a strong octupolar perturbation in an otherwise linear lattice, and under stationary parameters. We explore the importance of self-consistency by comparing results with a non-self-consistent model, where the space charge electric field is kept.
Date: May 19, 2003
Creator: Hofmann, I.; Franchetti, G.; Qiang, J. & Ryne, R.
System: The UNT Digital Library
Use of Numerical Models as Data Proxies for Approximate Ad-Hoc Query Processing (open access)

Use of Numerical Models as Data Proxies for Approximate Ad-Hoc Query Processing

As datasets grow beyond the gigabyte scale, there is an increasing demand to develop techniques for dealing/interacting with them. To this end, the DataFoundry team at the Lawrence Livermore National Laboratory has developed a software prototype called Approximate Adhoc Query Engine for Simulation Data (AQSim). The goal of AQSim is to provide a framework that allows scientists to interactively perform adhoc queries over terabyte scale datasets using numerical models as proxies for the original data. The advantages of this system are several. The first is that by storing only the model parameters, each dataset occupies a smaller footprint compared to the original, increasing the shelf-life of such datasets before they are sent to archival storage. Second, the models are geared towards approximate querying as they are built at different resolutions, allowing the user to make the tradeoff between model accuracy and query response time. This allows the user greater opportunities for exploratory data analysis. Lastly, several different models are allowed, each focusing on a different characteristic of the data thereby enhancing the interpretability of the data compared to the original. The focus of this paper is on the modeling aspects of the AQSim framework.
Date: May 19, 2003
Creator: Kamimura, R.; Abdulla, G.; Baldwin, C.; Critchlow, T.; Lee, B; Lozares, I. et al.
System: The UNT Digital Library
53 MHZ Feedforward beam loading compensation in the Fermilab main injector (open access)

53 MHZ Feedforward beam loading compensation in the Fermilab main injector

53 MHz feedforward beam loading compensation is crucial to all operations of the Main Injector. Recently a system using a fundamental frequency down converter mixer, a digital bucket delay module and a fundamental frequency up converter mixer were used to produce a one-turn-delay feedforward signal. This signal was then combined with the low level RF signal to the cavities to cancel the transient beam induced voltage. During operation they have shown consistently over 20 dB reduction in side-band voltage around the fundamental frequency during Proton coalescing and over 14 dB in multi-batch antiproton coalescing.
Date: May 19, 2003
Creator: al., Joseph E Dey et
System: The UNT Digital Library
QCD Results from the CDF Experiment at squareroot s = 1.96 TeV (open access)

QCD Results from the CDF Experiment at squareroot s = 1.96 TeV

First QCD results obtained from the CDF experiment using Run II data are reported. The Run II physics program at the Tevatron started in the spring of 2001, with protons and anti-protons colliding at an energy of {radical}s = 1.96 TeV. The size of the data sample already compares to that of Run I. Results presented here include the measurement of the inclusive jet cross section, a search for new particles decaying to dijets, and a study of diffractive dijet events.
Date: May 19, 2003
Creator: Gallinaro, Michele
System: The UNT Digital Library
2.5 MHz feedforward beam loading compensation in the Fermilab Main Injector (open access)

2.5 MHz feedforward beam loading compensation in the Fermilab Main Injector

There are five 2.5 MHz ferrite cavities (h = 28) in the Main Injector with an R/Q of 500 that are presently used for coalescing for the Tevatron. For use with the Fermilab Recycler, feedforward (FF) beam loading compensation (BLC) is required on these cavities because they will be required to operate at a net of 2 kV. Under current Recycler beam conditions, the beam-induced voltage is of this order. Recently a system using a digital bucket delay module operating at 53 MHz (h = 588) was used to produce a one-turn-delay feedforward signal. This signal was then combined with the low level RF signal to the 2.5 MHz cavities to cancel the beam induced voltage. During current operation they have shown consistently to operate with over a 20 dB reduction in beam loading.
Date: May 19, 2003
Creator: Dey, Joseph E.; Kourbanis, Ioanis & Steimel, James
System: The UNT Digital Library