Gold Beam Losses at the AGS Booster Injection. (open access)

Gold Beam Losses at the AGS Booster Injection.

Gold beam injection efficiency decreases in proportional to the beam loss in the AGS Booster. A close look shows that large number of electrons, ions, and neutral particles are created when the gold beam scrapes wall. To investigate the neutral particle production due to the beam loss, local vacuum measurement was made during the 1998 run. It shows that the pressure created by the Booster Au{sup 31+} beam loss at injection has a 35 ms decay time constant. The beam loss created pressure bump in the ring is about 20 meters long. When 3 x 10{sup 9} Gold ions scrapes wall, a pressure higher than 10{sup -7} Torr was created. The beam lifetime calculated using these parameters is in agreement with the observed one.
Date: March 29, 1999
Creator: Zhang, S. Y. & Ahrens, L. A.
System: The UNT Digital Library
A Cupronickel Rotating Band Pion Production Target for Muon Colliders. (open access)

A Cupronickel Rotating Band Pion Production Target for Muon Colliders.

A conceptual design is presented for a high power cupronickel pion production target. It forms a circular band in a horizontal plane with approximate dimensions of: 2.5 meters radius, 6 cm high and 0.6 cm thick. The target is continuously rotated at 3 m/s to carry heat away from the production region to a water cooling channel. Bunches of 16 GeV protons with total energies of 270 kl and repetition rates of 15 Hz are incident tangentially to arc of the target along the symmetry axis of a 20 Tesla solenoidal magnetic capture channel. The mechanical layout and cooling setup are described. Results are presented from realistic MARS Monte Carlo computer simulations of the pion yield and energy deposition in the target. ANSYS finite element calculations are beginning to give predictions for the resultant shock heating stresses.
Date: March 29, 1999
Creator: King, B. J.; Weggel, R. J.; Mokhov, N. V. & Moser, S. S.
System: The UNT Digital Library
Precision Magnetic Elements for the SNS Storage Ring. (open access)

Precision Magnetic Elements for the SNS Storage Ring.

Magnetic elements for an accumulator storage ring for a 1 GeV Spallation Neutron Source (SNS) have been under design. The accumulation of very high intensity protons in a storage ring requires beam optical elements of very high purity to minimize higher order resonances in the presence of space charge. The parameters of the elements required by the accumulator lattice design have been reported. The dipoles have a 17cm gap and are 124cm long. The quadrupoles have a physical length to aperture diameter ratio of 40cm/21cm and of 45cm/31cm. Since the elements have a large aperture and short length, optimizing the optical effects of magnet ends is the major design challenge. Two dimensional (2D) computer computations can, at least on paper, produce the desired accuracy internal to magnets, i.e. constant dipole fields and linear quadrupole gradients over the desired aperture to 1 x 10{sup -4}. To minimize undesirable end effects three dimensional (3D) computations can be used to design magnet ends. However, limitations on computations can occur, such as necessary finite boundary conditions, actual properties of the iron employed, hysteresis effects, etc., which are slightly at variance with the assumed properties. Experimental refinement is employed to obtain the desired precision.
Date: March 29, 1999
Creator: Danby, G.; Jackson, J. & Spataro, C.
System: The UNT Digital Library
A P-Carbon CNI Polarimeter for RHIC. (open access)

A P-Carbon CNI Polarimeter for RHIC.

The RHIC spin program requires excellent polarimetry so that the knowledge of the beam polarization does not limit the errors on the experimental measurements. However, polarimetry of proton beams with energies higher than about 30GeV poses a difficult challenge. For polarization monitoring during operation, a fast and reliable polarimeter is required that produces a polarization measurement with a 10% relative error within a few minutes. The p-Carbon elastic scattering in the Coulomb-Nuclear-Scattering (CNI) region has a calculable and large analyzing power, but detecting the recoil carbon needs sophisticated detector system and a very thin target. Experiment has been planned in the AGS. This paper describes the experimental setup in the AGS.
Date: March 29, 1999
Creator: Huang, H.; Bai, M.; Bunce, G.; Makdisi, Y.; Roser, T.; Imai, K. et al.
System: The UNT Digital Library
Design of a Resonant Extraction System for the AGS Booster. (open access)

Design of a Resonant Extraction System for the AGS Booster.

The Booster Application Facility (BAF) will employ heavy ion beams of many different ion species and at beam energies ranging from 0.04 to 3.07 GeV/nucleon. Resonant extraction is required in order to deliver a continuous stream of particles. In this report we describe the beam requirements and the system design. The basic design is a third integer resonant extraction process which employs a single thin magnetic septum and a thick septum ejector magnet The expected extraction efficiency is about 85%, based on the thin septum thickness and the predicted step size of the resonant beam at the septum. This is more than sufficient for the low intensity low energy heavy ion beams needed for the BAF. In this report we will present a detailed discussion of the design of the various elements and a discussion of the detailed modeling of resonant extraction from the AGS Booster. The extraction process was modeled using a BNL version of MAD which allowed us to interactively observe detailed particle tracking of the process. This was a key tool to have in hand which permitted us to pose and answer various questions in a very short period of time.
Date: March 29, 1999
Creator: Brown, K.; Cullen, J.; Glenn, J. W.; Lee, Y. Y.; Mcnerney, A.; Niederer, J. et al.
System: The UNT Digital Library
RHIC Beam Loss Monitor System Initial Operation. (open access)

RHIC Beam Loss Monitor System Initial Operation.

The RHIC Beam Loss Monitor (BLM) System is designed to prevent beam loss quenching of the superconducting magnets, and acquire loss data. Four hundred ion chambers are located around the rings to detect losses. The required 8-decade range in signal current is compressed using an RC pre- integrator ahead of a low current amplifier. A beam abort may be triggered if fast or slow losses exceed programmable threshold levels. A micro-controller based VME module sets references and gains and reads trip status for up to 64 channels. Results obtained with the detectors in the RHIC Sextant Test and the prototype electronics in the AGS-to-RHIC (AtR) transfer line are presented along with the present status of the system.
Date: March 29, 1999
Creator: Witkover, R. L.; Michnoff, R. J. & Geller, J. M.
System: The UNT Digital Library
The Design of a Liquid Lithium Lens for a Muon Collider. (open access)

The Design of a Liquid Lithium Lens for a Muon Collider.

The last stage of ionization cooling for the muon collider requires a multistage liquid lithium lens. This system uses a large ({approx}0.5 MA) pulsed current through liquid lithium to focus the beam while energy loss in the lithium removes momentum which will be replaced by linacs. The beam optics are designed to maximize the 6 dimensional transmission from one lens to the next while minimizing emittance growth. The mechanical design of the lithium vessel is constrained by a pressure pulse due to sudden ohmic heating, and the resulting stress on the Be window. We describe beam optics, the liquid lithium pressure vessel, pump options, power supplies, as well as the overall optimization of the system.
Date: March 29, 1999
Creator: Hassanein, A.; Norem, J.; Reed, C.; Palmer, R. B.; Silvestrov, G.; Vsevolozhskaya, T. A. et al.
System: The UNT Digital Library
Beam Instrumentation for the Spallation Neutron Source Ring. (open access)

Beam Instrumentation for the Spallation Neutron Source Ring.

The Spallation Neutron Source (SNS) will be constructed by a multi-laboratory collaboration with BNL responsible for the transfer lines and ring. [1] The 1 MW beam power necessitates careful monitoring to minimize un-controlled loss. This high beam power will influence the design of the monitors in the high energy beam transport line (HEBT) from linac to ring, in the ring, and in the ring-to-target transfer line (RTBT). The ring instrumentation must cover a 3-decade range of beam intensity during accumulation. Beam loss monitoring will be especially critical since un-controlled beam loss must be kept below 10{sup -4}. A Beam-In-Gap (BIG) monitor is being designed to assure out-of-bucket beam will not be lost in the ring.
Date: March 29, 1999
Creator: Witkover, R. L.; Cameron, P. R.; Shea, T. J.; Connolly, R. C. & Kesselman, M.
System: The UNT Digital Library
Beam-Loss Driven Design Optimization for the Spallation Neutron Source (SNS) Ring. (open access)

Beam-Loss Driven Design Optimization for the Spallation Neutron Source (SNS) Ring.

This paper summarizes three-stage design optimization for the Spallation Neutron Source (SNS) ring: linear machine design (lattice, aperture, injection, magnet field errors and misalignment), beam core manipulation (painting, space charge, instabilities, RF requirements), and beam halo consideration (collimation, envelope variation, e-p issues etc.).
Date: March 29, 1999
Creator: Wei, J.; Beebe-Wang, J.; Blaskiewicz, M.; Cameron, P.; Danby, G.; Gardner, C. J. et al.
System: The UNT Digital Library
A High Power RF Coupler Design for Muon Cooling RF Cavities. (open access)

A High Power RF Coupler Design for Muon Cooling RF Cavities.

We present a high power RF coupler design for an interleaved {pi}/2 805 MHz standing wave accelerating structure proposed for an muon cooling experiment at FNAL. The coupler, in its simplest form, is a rectangular waveguide directly connected to an accelerating Cell through an open slot on the cavity side-wall or end-plates. Two of such couplers are needed to feed the interleaved cavities. Current high power RF test requires the coupler to be at critical coupling. Numerical simulations on the coupler designs using MAFIA will be presented.
Date: March 29, 1999
Creator: Corlett, J.; Li, Derun; Rimmer, R.; Holtkamp, N.; Moretti, A. & Kirk, H. G.
System: The UNT Digital Library
Interaction Region Local Correction for the Large Hadron Collider. (open access)

Interaction Region Local Correction for the Large Hadron Collider.

The performance of the Large Hadron Collider (LHC) at collision energy is limited by the field quality of the interaction region (IB) quadrupoles and dipoles. In this paper we study the impact of the expected field errors of these magnets on the dynamic aperture (DA). Since the betatron phase advance is well defined for magnets that are located in regions of large beta functions, local corrections can be very effective and robust. We compare possible compensation schemes and propose a corrector layout to meet the required DA performance.
Date: March 29, 1999
Creator: Wei, J.; Fischer, W.; Ptitsin, V.; Ostojic, R. & Strait, J.
System: The UNT Digital Library
Muon Colliders - Ionization Cooling and Solenoids. (open access)

Muon Colliders - Ionization Cooling and Solenoids.

For a muon collider, to obtain the needed luminosity, the phase space volume must be greatly reduced within the muon life time. The ionization cooling is the preferred method used to compress the phase space and reduce the emittance to obtain high luminosity muon beams. Alternating solenoid lattices has been proposed for muon colliders, where the emittance are huge. We present an overview, discuss formalism, transfer maps for solenoid magnets and beam dynamics.
Date: March 29, 1999
Creator: Parsa, Z.
System: The UNT Digital Library
The Application of the SXF Lattice Description and the UAL Software Environment to the Analysis of the LHC. (open access)

The Application of the SXF Lattice Description and the UAL Software Environment to the Analysis of the LHC.

A software environment for accelerator modeling has been developed which includes the UAL (Unified Accelerator Library), a collection of accelerator physics libraries with a Per1 interface for scripting, and the SXF (Standard eXchange Format), a format for accelerator description which extends the MAD sequence by including deviations from design values. SXF interfaces have been written for several programs, including MAD9 and MAD8 via the doom database, Cosy, TevLat and UAL itself, which includes Teapot++. After an overview of the software we describe the application of the tools to the analysis of the LHC lattice stability, in the presence of alignment and coupling errors, and to the correction of the first turn and closed orbit in the machine.
Date: March 29, 1999
Creator: Fischer, W.; Pilat, F. & Ptitson, V.
System: The UNT Digital Library
Processing and Analysis of the Measured Alignment Errors for Rhic. (open access)

Processing and Analysis of the Measured Alignment Errors for Rhic.

All elements of the Relativistic Heavy Ion Collider (RHIC) have been installed in ideal survey locations, which are defined as the optimum locations of the fiducials with respect to the positions generated by the design. The alignment process included the presurvey of all elements which could affect the beams. During this procedure a special attention was paid to the precise determination of the quadrupole centers as well as the roll angles of the quadrupoles and dipoles. After installation the machine has been surveyed and the resulting as-built measured position of the fiducials have been stored and structured in the survey database. We describe how the alignment errors, inferred by comparison of ideal and as-built data, have been processed and analyzed by including them in the RHIC modeling software. The RHIC model, which also includes individual measured errors for all magnets in the machine and is automatically generated from databases, allows the study of the impact of the measured alignment errors on the machine.
Date: March 29, 1999
Creator: Pilat, F.; Hemmer, M.; Ptitsin, V.; Tepikian, S. & Trbojevic, D.
System: The UNT Digital Library
US-LHC Magnet Database and Conventions. (open access)

US-LHC Magnet Database and Conventions.

The US-LHC Magnet Database is designed for production-magnet quality assurance, field and alignment error impact analysis, cryostat assembly assistance, and ring installation assistance. The database consists of tables designed to store magnet field and alignment measurements data and quench data. This information will also be essential for future machine operations including local IR corrections.
Date: March 29, 1999
Creator: Wei, J.; McChesney, D.; Jain, A.; Peggs, S.; Pilat, F.; Bottura, L. et al.
System: The UNT Digital Library
Feedback Design Method Review and Comparison. (open access)

Feedback Design Method Review and Comparison.

Different methods for feedback designs are compared. These includes classical Proportional Integral Derivative (P. I. D.), state variable based methods like pole placement, Linear Quadratic Regulator (L. Q. R.), H-infinity and p-analysis. These methods are then applied for the design and analysis of the RHIC phase and radial loop, yielding a performance, stability and robustness comparison.
Date: March 29, 1999
Creator: Onillon, E.
System: The UNT Digital Library
AGS Resonant Extraction With High Intensity Beams. (open access)

AGS Resonant Extraction With High Intensity Beams.

The Brookhaven AGS third integer resonant extraction system allows the AGS to provide high quality, high intensity 25.5 GeV/c proton beams simultaneously to four target stations and as many as 8 experiments. With the increasing intensities (over 7 x 10{sup 13} protons/pulse) and associated longer spill periods (2.4 to 3 seconds long), we continue to run with low losses and high quality low modulation continuous current beams.[1] Learning to extract and transport these higher intensity beams has required a process of careful modeling and experimentation. We have had to learn how to correct for various instabilities and how to better match extraction and the transport lines to the higher emittance beams being accelerated in the AGS. Techniques employed include ''RF'' methods to smooth out momentum distributions and fine structure. We will present results of detailed multi-particle tracking modeling studies which enabled us to develop a clear understanding of beam loss mechanisms in the transport and extraction process. We will report on our status, experiences, and the present understanding of the intensity limitations imposed by resonant extraction and transport to fixed target stations.
Date: March 29, 1999
Creator: Ahrens, L.; Brown, K.; Glenn, J. W.; Roser, T.; Tsoupas, N. & Vanasselt, W.
System: The UNT Digital Library
A Solenoid Capture System for Neutrino Production. (open access)

A Solenoid Capture System for Neutrino Production.

This paper describes the use of a high field solenoidal magnet to capture secondary pions from the production target. The captured pions subsequentially decay to produce the neutrino beam. A pion capture system using a high field solenoid magnet has been proposed for the muon collider[1]. This technology would also be available for neutrino beam production. It will be shown that a high field solenoid would produce a larger flux of neutrinos with energy, E{sub v} < 1.3 GeV, than a neutrino beam produced with a horn system. The {nu}{sub e}, {bar {nu}}{sub e} flux contamination in the solenoid neutrino beam is only 0.15%.
Date: March 29, 1999
Creator: Diwan, M.; Kahn, S. & Palmer, R. B.
System: The UNT Digital Library
Simulation, Generation, and Characterization of High Brightness Electron Source at 1 GV/m Gradient. (open access)

Simulation, Generation, and Characterization of High Brightness Electron Source at 1 GV/m Gradient.

This paper describes computer simulations and measurements on an electron bunch from a pulsed, high gradient gap. MAFIA and PBGUNS were used to calculate the emittance, brightness and energy spread of the electron beam for peak currents ranging from 10A to 1 kA and pulse durations ranging from 0.3 ps to 10 ps. Under optimum conditions, normalized emittance of 10{sup -7} {pi} m-rad, beam brightness of 3 x 10{sup 15} A/(m-rad){sup 2} and energy spread of 0.15% were obtained. A pulsed high voltage with 1 MV amplitude, and {approx}1 ns duration was applied to the diode with an interelectrode gap ranging from 2 mm to 0.5 mm. Copper cathodes with three different surface preparations; diamond polished, diamond turned and chemically cleaned, have been tested for their voltage hold-off properties under this high gradient and the Fowler-Nordheim plots were generated. The diamond polished OFC class II copper was shown to consistently produce lower dark current and higher hold-off voltage. Photoemission studies have been made using light from a KrF excimer. The field enhancement factor for photoemission was calculated to be 5, an order of magnitude smaller than the dark current beta for a similar surface.
Date: March 29, 1999
Creator: Srinivasan-Rao, T.; Schill, J.; Ben-Zvi, Ilan; Batchelor, K.; Farrell, J. P.; Smedley, J. et al.
System: The UNT Digital Library
RHIC Beam Synchronous Trigger Module. (open access)

RHIC Beam Synchronous Trigger Module.

The RHIC Beam Synchronous Event System consists of centralized event encoders (one for each collider ring), which operate from the RF clock and the revolution clock provided by the RHIC RF system, and distributed embedded decoders. The Beam Synchronous Trigger Module (V124) is a general purpose 6U x 4HP, VMEbus controlled module that is compatible with the RHIC Beam Synchronous Event System and is designed to provide clocks and triggers for collider data acquisition systems and experiments. The V124 Module contains a separate memory (Bunch Fill Mask RAM) for each channel that is software configurable with the pattern of filled buckets (Bunch Fill Pattern) to permit bunch synchronous triggering/clocking. This module provides eight identical channels that can be configured independently or in pairs, and a buffered RF Clock output.
Date: March 29, 1999
Creator: Hartmann, H. & Kerner, T.
System: The UNT Digital Library
The RHIC/AGS Online Model Environment: Design and Overview. (open access)

The RHIC/AGS Online Model Environment: Design and Overview.

An integrated online modeling environment is currently under development for use by AGS and RHIC physicists and commissioners. This environment combines the modeling efforts of both groups in a CDEV [1] client-server design, providing access to expected machine optics and physics parameters based on live and design machine settings. An abstract modeling interface has been designed as a set of adapters [2] around core computational modeling engines such as MAD and UAL/Teapot++ [3]. This approach allows us to leverage existing survey, lattice, and magnet infrastructure, as well as easily incorporate new model engine developments. This paper describes the architecture of the RHIC/AGS modeling environment, including the application interface through CDEV and general tools for graphical interaction with the model using Tcl/Tk. Separate papers at this conference address the specifics of implementation and modeling experience for AGS and RHIC.
Date: March 29, 1999
Creator: Satogata, T.; Brown, K.; Pilat, F.; Tafti, A. A.; Tepikian, S. & Van Zeijts, J.
System: The UNT Digital Library
Pulsing a 4.1 MW Motor Generator System to 34 MW Peak Power Under Constant Input Power Operation. (open access)

Pulsing a 4.1 MW Motor Generator System to 34 MW Peak Power Under Constant Input Power Operation.

Brookhaven operates a 9 MW motor generator, made by Siemens, as part of the main magnet power supply of the Alternating Gradient Synchrotron (AGS) accelerator. A cycloconverter power supply system is utilized to ensure that during pulsing the main magnets of the AGS up to 50 MW peak power, the input power of the motor generator remains constant. There is also another motor generator (MG set) at Brookhaven, a 40 year old system manufactured by Westinghouse. This MG set could be pulsed up to 34 MW peak power while the input average power should not exceed. 4.1 M&V. A project is underway to upgrade this MG system and it's controls, so it could be used as a spare while doing maintenance on the Siemens MG and thus not interrupting the RHIC physics program. The purpose of this paper is to show that it is possible to pulse the AGS magnets using the Westinghouse MG system without utilizing a cycloconverter power supply, and still be able to maintain the input power to the motor generator constant. Calculations will be provided to show that we can pulse the position of the liquid rheostat in the motor rotor circuit to support the above, …
Date: March 29, 1999
Creator: Marneris, I.; Badea, V.; Bannon, M.; Bonati, R.; Danowaki, G.; Sandberg, J. et al.
System: The UNT Digital Library
Denoising of human speech using combined acoustic and em sensor signal processing (open access)

Denoising of human speech using combined acoustic and em sensor signal processing

Low Power EM radar-like sensors have made it possible to measure properties of the human speech production system in real-time, without acoustic interference. This greatly enhances the quality and quantify of information for many speech related applications. See Holzrichter, Burnett, Ng, and Lea, J. Acoustic. Soc. Am. 103 (1) 622 (1998). By using combined Glottal-EM- Sensor- and Acoustic-signals, segments of voiced, unvoiced, and no-speech can be reliably defined. Real-time Denoising filters can be constructed to remove noise from the user's corresponding speech signal.
Date: November 29, 1999
Creator: Ng, L C; Burnett, G C; Holzrichter, J F & Gable, T J
System: The UNT Digital Library
Pion Yield vs. Geometry of Target and -20T Pulse Solenoid for a Muon Collider Experiment. (open access)

Pion Yield vs. Geometry of Target and -20T Pulse Solenoid for a Muon Collider Experiment.

The Muon Collider Collaboration is proposing a pion-capture experiment that employs BNL's Alternating Gradient Synchrotron, a liquid metal target, and a pulse solenoid precooled by liquid nitrogen. This paper compares the yield with various target diameters, orientations and magnetic field profiles. To equalize costs, all magnets have the same mass, 12 metric tons. The magnet has two nested shells, energized sequentially. The outer set of coils, energized at 4 MVA, generates {approx}1/3 of the field in the target, most of the field downstream from it, and stores {approx}21 MJ, from which to energize the inner coil. The computer code MARS predicts that the meson yield 5 meters from the target can be {approx}0.35 per 16-GeV proton. This is with a mercury target of 20 mm diameter and 0.3 m length, tilted 100 mr from the field axis. The magnet field is 20 T, averaged over the target, ramping downward as (1+5z){sup -1} over a 3 m length, while the bore increases inversely with the square root of the field.
Date: March 29, 1999
Creator: Weggel, R. J. & Mokhov, N. V.
System: The UNT Digital Library