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Module strap tests and how they effect the 25 cm stack construction

Description: We were asked at the previous Atlas collaboration meeting to confirm our proposal that the Argonne design option could maintain the tie straps in a prestressed condition after welding. This was deemed necessary to maintain compression loading of the steel plate stack. The compression load requirement was set at a load equivalent to that necessary to maintain continuity of the stack using friction. We will attempt to prove that through the strap testing and the ultimate construction of the 25 cm prototype stack that we have in fact met these requirements.
Date: September 6, 1994
Creator: Hill, N.F.
Partner: UNT Libraries Government Documents Department

The final phase of the ATLAS control system upgrade

Description: The ATLAS facility (Argonne Tandem-Linac Accelerator System) is located at the Argonne National Laboratory. The facility is a tool used in nuclear and atomic physics research focusing primarily on heavy-ion physics. Due to the complexity of the operation of the facility, a computerized control system has always been required. The nature of the design of the accelerator has allowed the accelerator to evolve over time to its present configuration. The control system for the accelerator has evolved as well, primarily in the form of additions to the original design. A project to upgrade the ATLAS control system replacing most of the major original components was first reported on in the Fall of 1992 during the Symposium Of North Eastern Accelerator Personnel (SNEAP) at the AECL, Chalk River Laboratories. A follow-up report was given in the Fall of 1993 at the First Workshop on Applications of Vsystem Software and Users` Meeting at the Brookhaven National Laboratory. This project is presently in its third and final phase. This paper briefly describes the ATLAS facility, summarizes the control system upgrade project, and explains the intended control system configuration at the completion of the final phase of the project.
Date: December 1, 1995
Creator: Munson, F.; Kramer, S. & Tieman, B.
Partner: UNT Libraries Government Documents Department

Accelerator complex for a radioactive ion beam facility at ATLAS

Description: Since the superconducting heavy ion linac ATLAS is an ideal post-accelerator for radioactive beams, plans are being developed for expansion of the facility with the addition of a driver accelerator, a production target/ion source combination, and a low q/m pre-accelerator for radioactive ions. A working group including staff from the ANL Physics Division and current ATLAS users are preparing a radioactive beam facility proposal. The present paper reviews the specifications of the accelerators required for the facility.
Date: June 1, 1995
Creator: Nolen, J.A.
Partner: UNT Libraries Government Documents Department

Experiences with stacking the first four ATLAS submodules at Argonne

Description: This note is to review our experience at Argonne with assembling the first four sumodules constructed at this location. We will try to cover all of the experiences, and at the end add some comments about changes that were incorporated into the current modules, and suggested changes that may be incorporated into future modules.
Date: February 22, 1996
Creator: Hill, N.; Proudfoot, J.; Wood, K.; Balka, L.; Keyser, C. & Caird, A.
Partner: UNT Libraries Government Documents Department

The production and transport of radioactive {sup 17}F at ATLAS for research

Description: A secondary beam of radioactive {sup 17}F was produced at the ATLAS accelerator and delivered to an experimental target station with an intensity of as much as 5{circ}10{sup 5} ions/s for use in the research program. Beams of {sup 17}F were produced via the p({sup 17}O, {sup 17}F)n or d({sup 16}O, {sup 17}F)n reactions by bombarding a gas-filled cell with up to 300 pnA beams of {sup 17}O or {sup 16}O from the ATLAS superconducting linac. The gas target, with HAVAR windows, was maintained at pressures as high as 500 Torr. The beam quality was dominated by small-angle scattering in the gas cell windows, by the reaction kinematics and beamline acceptance. Detailed beam parameters are presented. Plans for relocation of the target to allow improved capture efficiency and acceleration or de-acceleration of the secondary beam will also be discussed.
Date: June 1, 1997
Creator: Harss, B.; Berger, J.C. & Borasi, F.
Partner: UNT Libraries Government Documents Department

A new 14 GHz electron-cyclotron-resonance ion source (ECRIS) for the heavy ion accelerator facility ATLAS: a status report

Description: A new 14 GHz ECRIS has been designed and built over the last 2 years. The source, a modification of the Berkeley AECR, incorporates the latest results from ECR developments to produce intense beams of highly charged ions, i.e., an improved electron confinement with an axial magnetic mirror ratio of 3.5 and a radial magnetic field inside the plasma chamber of 1.0 T. The aluminium plasma chamber and extraction electrode as well as a biased disk on axis at the microwave injection side donate additional electrons to the plasma, making use of the large secondary electron yield from Al oxide. Slots in the plasma chamber allow for radial pumping which increases the AECR performance. The source will also be capable of additional ECR plasma heating using two frequencies simultaneously to increase the electron energy gain for producing high charge states. To be able to deliver usable intensities of the heaviest ion beams, the design will also allow for axial access for metal evaporation ovens and solid material samples using plasma sputtering. Main design goal is to produce several e{mu}A of U{sup 34+} in order to obtain Coulomb- barrier energies from ATLAS without further stripping.
Date: November 1, 1996
Creator: Schlapp, M.; Vondrasek, R.C.; Szczech, J.; Billquist, P.J.; Pardo, R.C. & Xie, Z.Q.
Partner: UNT Libraries Government Documents Department

A new 14 GHz Electron-Cyclotron-Resonance Ion Source (ECRIS) for the heavy ion accelerator facility ATLAS

Description: A 14 GHz Electron-Cyclotron-Resonance Ion Source (ECRIS) has been designed and built at Argonne National Laboratory. The source is a modification of the AECR at Berkeley and incorporates the latest results from ECR developments to produce intense beams of highly charged ions, including an improved magnetic confinement of the plasma electrons with an axial mirror ratio of 3.5. The aluminum plasma chamber and extraction electrode as well as a biased disk on axis at the microwave injection side donates additional electrons to the plasma, making use of the large secondary electron yield from aluminum oxide. The source is capable of ECR plasma heating using two different frequencies simultaneously to increase the electron energy gain for the production of high charge states. The main design goal is to produce several e{mu}A of at least {sup 238}U{sup 35+} in order to accelerate the beam to coulomb-barrier energies without further stripping. First charge state distributions for gaseous elements have been measured and 210 e{mu}A {sup 16}O{sup 7+} has been achieved. A normalized 90% emittance from 0.1 to 0.2 {pi} mm{sm_bullet}mrad for krypton and oxygen beam has been found.
Date: November 1997
Creator: Schlapp, M.; Pardo, R. C.; Vondrasek, R. C.; Billquist, P. J. & Szczech, J.
Partner: UNT Libraries Government Documents Department

Report to users of ATLAS, January 1998

Description: This report is aimed at informing users about the operating schedule, user policies, and recent changes in research capabilities. It covers the following subjects: (1) status of the Argonne Tandem-Linac Accelerator System (ATLAS) accelerator; (2) the move of Gammasphere from LBNL to ANL; (3) commissioning of the CPT mass spectrometer at ATLAS; (4) highlights of recent research at ATLAS; (5) Program Advisory Committee; and (6) ATLAS User Group Executive Committee.
Date: January 1, 1998
Creator: Ahmad, I. & Hofman, D.
Partner: UNT Libraries Government Documents Department

Recent developments in ECRIS technology at Argonne National Laboratory and the New ATLAS 14 GHz ECRIS Project

Description: A summary of recent developments in ECRIS technology taking place at Argonne National Laboratory is presented in this paper. A pulsed laser for ablation of solid material into the source plasma has been used online with the ATLAS PII-ECRIS and has allowed direct time measurements to be made which verify and quantify sequential, step-by-step ionization taking place in an ECRIS. In addition, during the course of these laser studies a method was discovered which, from an operational viewpoint, represents an important new method for incorporating solid materials into an ECRIS. We also report on a new 14 GHz ECRIS currently under construction at Argonne. This new ECRIS, along with a new 300 kV high voltage platform and building addition, will further the capabilities of the ATLAS facility by providing the accelerator with a second, independent ECRIS.
Date: May 1, 1995
Creator: Harkewicz, R.; Billquist, P.J. & Pardo, R.C.
Partner: UNT Libraries Government Documents Department

Long-term operating experience for the ATLAS superconducting resonators

Description: Portions of the ATLAS accelerator have been operating now for over 21 years. The facility has accumulated several million resonator-hours of operation at this point and has demonstrated the long-term reliability of RF superconductivity. The overall operating performance of the ATLAS facility has established a level of beam quality, flexibility, and reliability not previously achieved with heavy-ion accelerator facilities. The actual operating experience and maintenance history of ATLAS are presented for ATLAS resonators and associated electronics systems. Solutions to problems that appeared in early operation as well as current problems needing further development are discussed.
Date: December 21, 1999
Creator: Pardo, R. & Zinkann, G.
Partner: UNT Libraries Government Documents Department

The ATLAS level 2 trigger supervisor.

Description: This paper presents an overview of the hardware and software proposed for the ATLAS level 2 Trigger ROI Builder/Supervisor. The essential requirements of this system are that it operate at the design Level 1 Trigger rate of 100kHz and that it support the technical requirements of the architectures suggested for the ATLAS Level 2 Trigger. Commercial equipment and software support are used to the maximum extent possible, with support from dedicated hardware. Timing requirements and latencies are discussed and simulation results are presented.
Date: April 3, 1997
Creator: Abolins, M.; Blair, R. E.; Dawson, J. W.; Owen, D.; Pope, B. G.; Schlereth, J. L. et al.
Partner: UNT Libraries Government Documents Department

Completion of the ATLAS control system upgrade.

Description: In the fall of 1992 at the SNEAP(Symposium of North Eastern Accelerator Personnel) a project to up grade the ATLAS (Argonne Tandem Linear Accelerator System) control system was first reported. Not unlike the accelerator it services the control system will continue to evolve. However, the first of this year has marked the completion of this most recent upgrade project. Since the control system upgrade took place during a period when ATLAS was operating at a record number of hours, special techniques were necessary to enable the development of the new control system ''on line'' while still saving the needs of normal operations. This paper reviews the techniques used for upgrading the ATLAS control system while the system was in use. In addition a summary of the upgrade project and final configuration, as well as some of the features of the new control system is provided.
Date: November 30, 1998
Creator: Munson, F. H.
Partner: UNT Libraries Government Documents Department

Design parameters, goals, and status of the new ATLAS ECR ion source

Description: A new 14 GHz ECR ion source for the ATLAS facility is under construction. The new source is an evolution of the 14 GHz AECR Lawrence Berkeley source. The new source will feature an all aluminum hexapole main chamber and enhanced peak radial and solenoid magnetic fields compared to the existing AECR. Most of the other design features of the existing source are maintained in this design. The new source will be mounted on a new 300 kV high voltage platform in order to match the velocity requirements of the existing PII injector linac. Achieving the very precise goal of a few electrical microamps of {sup 238}U{sup +33} from this source will allow the ATLAS facility to provide Coulomb-barrier energies of uranium without the use of an additional stripper foil and will significantly enhance the capabilities of ATLAS for the heaviest of beams. The project status and more details of the source system design are discussed.
Date: December 1, 1995
Creator: Pardo, R.C.; Harkewicz, R. & Billquist, P.J.
Partner: UNT Libraries Government Documents Department

The role of space charge in the performance of the bunching system for the ATLAS Positive Ion Injector

Description: The bunching system of the ATLAS Positive Ion Injector consists of a four-frequency harmonic buncher, a beam-tail removing chopper, and a 24.25 MHz spiral resonator sine-wave rebuncher. The system is designed to efficiently create beam pulses of approximately 0.25 nsec FWHM for injection into mid acceleration by the ATLAS superconducting linac. Studies of the effect of space charge on the performance of the system have been undertaken and compared to simulations as part of the design process for a new bunching system to be developed for a second ion source. Results of measurements and modeling studies indicate that the present system suffers significant bunching performance deterioration at beam currents as low as 5 e{mu}A for {sup 238}U{sup 26+} at a velocity of {beta}=0.0085. The low beam current tolerance of the present system is in reasonable agreement with computer simulation. Studies of two alternatives to the present bunching system are discussed and their limitations are explored.
Date: July 1, 1995
Creator: Pardo, R.C. & Smith, R.
Partner: UNT Libraries Government Documents Department

Longitudinal emittance oscillation in a superconducting drift tube linac

Description: In drift tube linacs a beam energy spread results form the finite beam size. Radial variation of the axial accelerating field induces a beam energy spread, which, in general, will accumulate as the beam passes through successive drift tubes. This paper shows that under some conditions of periodic transverse focusing and longitudinal phase focusing, the correlation between the longitudinal and transverse motion can be used to correct the energy spread. The process of achieving such a correction is first described in a simplified situation, and then demonstrated for a particular tuning using a ray-tracing program which models a low velocity and low charge state linac designed for radioactive ion beams.
Date: July 1, 1995
Creator: Kim, J.W. & Shepard, K.W.
Partner: UNT Libraries Government Documents Department

Full supersymmetry simulation for ATLAS in DC1

Description: This note reports results from a simulation of 100k events for one example of a minimal SUGRA supersymmetry case at the LHC using full simulation of the ATLAS detector. It was carried out as part ATLAS Data Challenge 1.
Date: January 26, 2004
Creator: Biglietti, Michela; Brochu, Frederic; Costanzo, Davide; De, Kaushik; Duchovni, Ehud; Gupta, Ambreesh et al.
Partner: UNT Libraries Government Documents Department

A low-charge-state injector linac for ATLAS

Description: The design of a low-charge-state linac which is capable of accelerating, for example, {sup 132}Sn{sup 1+} for injection into the existing heavy-ion linac ATLAS is discussed. The injector linac is intended for radioactive beam applications, and will accelerate a low- charge-state beam to energies of 500 keV/nucleon, at which point the ions can be stripped to charge states sufficiently high to be injected into ATLAS. A primary design goal has been to extend the very good longitudinal beam quality typical of ATLAS to low charge state beams. The proposed injector linac consists of several elements. First is a gridded-gap four-harmonic buncher and a short (normally-conducting) 12 MHz RFQ structure, both operating on a 350 kV open-air variable-voltage platform. Then comes an array of 24 Mhz and 48 Mhz superconducting interdigital accelerating structures interspersed with superconducting quadrupole transverse focusing elements. Numerical ray-tracing studies indicate that a transverse acceptance greater than 0.25{pi} mm-mrad can be obtained while simultaneously limiting longitudinal emittance growth to a very few keV-nsec.
Date: July 1, 1995
Creator: Shepard, K.W. & Kim, J.W.
Partner: UNT Libraries Government Documents Department

A low-cost non-intercepting beam current and phase monitor for heavy ions

Description: A low cost ion beam measurement system has been developed for use at ATLAS. The system provides nondestructive phase and intensity measurement of passing ion beam bunches by sensing their electric fields. Bunches traverse a short tubular electrode thereby inducing displacement currents. These currents are brought outside the vacuum jacket where a lumped inductance resonates electrode capacitance at one of the bunching harmonic frequencies. This configuration yields a basic sensitivity of a few hundred millivolts signal per microampere of beam current. Beam induced radiofrequency signals are summed against an offset frequency generated by the master oscillator. The resulting difference frequency conveys beam intensity and bunch phase information which is sent to separate processing channels. One channel utilizes a phase locked loop to stabilize phase readings during microsecond beam drop outs. The other channel uses a linear full-wave active rectifier circuit which converts sine wave signal amplitude to a DC voltage representing beam current. Plans are in progress to install this new diagnostic at several locations in ATLAS which should help shorten the tuning cycle of new ion species.
Date: July 1, 1995
Creator: Bogaty, J.M. & Clifft, B.E.
Partner: UNT Libraries Government Documents Department

Extended barrel support saddle design and analysis.

Description: This paper summarizes the extensive structural analysis and design of the support saddles for the Extended Barrel of the ATLAS Tilecalorimeter that has taken place at Argonne National Laboratory over the past several months. This work has been a continuation and expansion of work that has taken place over the course of several years within the ATLAS Tilecalorimeter collaboration. This paper will be divided into four main sections. Section 1 is the introduction to the analysis and will give a brief history of the work that had previously been done. Section 2 examines the design and structural analysis that has occurred on the support saddles. The design of the support saddles has evolved over the last few months. There are three main analyses of the saddles that are discussed in Section 2. First, the forces that act upon the support saddles and the resulting deflections and stresses are examined when the support saddle is subjected only to gravity loading. Next, the saddles are examined when subjected to a combination of gravity and a seismic load of .15g in the X, Y, and Z directions. Finally, the saddles are analyzed when subjected to a combination of gravity, magnetic, and seismic loading. Section 3 describes a detailed analysis of the back cryostat support structure in the Extended Barrel. This design has evolved significantly throughout the analysis process and every design iteration and analysis is described in detail. The initial design is described in Section 3.1 that analyzed the back cryostat support only under vertical static loading. Section 3.2 then examines the stiffening of the cryostat support plate that had to be included in the design in order to provide sufficient stiffness in the case of seismic loading in the X, Y, and Z directions. Finally, Section 3.3 describes the final design, which ...
Date: February 27, 2002
Creator: Guarino, V.; Grudzinski, J. & Petereit, E.
Partner: UNT Libraries Government Documents Department

The positive-ion injector of ATLAS: Design and operating experience

Description: The recently completed Positive-Ion Injector for the heavy-ion accelerator ATLAS is a replacement for the tandem injector of the present tandem-linac system. Unlike the tandem, the new injector provides ions from the full range of the periodic table. The concept for the new injector, which consists of an ECR ion source on a voltage platform coupled to a very-low-velocity superconducting linac, introduces technical problems and uncertainties that are well beyond those encountered previously for superconducting linacs. The solution to these problems and their relationship to performance are outlined, and experience in the operation of ATLAS with its new injector is discussed.
Date: December 1, 1992
Creator: Bollinger, L. M.; Pardo, R. C.; Shepard, K. W.; Billquist, P. J.; Bogaty, J. M.; Clifft, B. E. et al.
Partner: UNT Libraries Government Documents Department

Physics division annual report 2006.

Description: This report highlights the activities of the Physics Division of Argonne National Laboratory in 2006. The Division's programs include the operation as a national user facility of ATLAS, the Argonne Tandem Linear Accelerator System, research in nuclear structure and reactions, nuclear astrophysics, nuclear theory, investigations in medium-energy nuclear physics as well as research and development in accelerator technology. The mission of nuclear physics is to understand the origin, evolution and structure of baryonic matter in the universe--the core of matter, the fuel of stars, and the basic constituent of life itself. The Division's research focuses on innovative new ways to address this mission.
Date: February 28, 2008
Creator: Glover, J. & Physics
Partner: UNT Libraries Government Documents Department

A study of beam chopping options for the ATLAS Positive Ion Linac

Description: Unbunched beam components from the injection beam bunching system must be removed prior to acceleration in the ATLAS Positive Ion Injector Linac (PII). A sine wave chopper has been used for this purpose up to now. Such a device can have a significant detrimental effect on the longitudinal and transverse beam emittance of heavy-ion beams which can be sufficiently severe to limit the overall beam quality from the ATLAS accelerator. A study of the optimum chopper configuration and chopper type was undertaken as part of a new ion source project for ATLAS. A transmission line chopper and a two harmonic chopper were investigated as alternatives to the conventional sine wave chopper. This paper reports the results of that investigation and discusses the design of the selected transmission line chopper.
Date: October 1, 1996
Creator: Pardo, R.C.; Bogaty, J.M. & Clifft, B.E.
Partner: UNT Libraries Government Documents Department

Conceptual design of the inner cryostat support and jack

Description: The Endcap Cryostat will be supported by the End Barrel Tilecalorimeter at four points. The outer support points will be carried by a structure that is external to the End Barrel modules while the inner support points will be directly on the modules. This paper concerns the design of these inner support points. The design parameters for the inner support points are: (1) must be able to support twice the front load from the Endcap Cryostat (70 tons); (2) the support point must make contact on the inner radius surface provided on the Endcap Cryostat; (3) vertical adjust must be allowed of up to {+-} 6mm; (4) the support must be a simple support; (5) the support must be contained within the envelope of one End Barrel submodule.
Date: January 11, 1998
Creator: Guarino, V. & Petereit, E.
Partner: UNT Libraries Government Documents Department