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Three dimensional field analysis for the AGS combined function magnets

Description: In order to study the particle trajectories in the fringe field of the AGS ring during the single bunch multiple extraction (or fast extraction) from the AGS to the muon g-2 experiment and to the RHIC, the magnetic field of the AGS combined function magnets were calculated b using the TOSCA program. The results are compared with the field maps of the previous measurements. The particle tracking is achieved by using the TOSCA program post-processor.
Date: June 1, 1993
Creator: Meng, W. & Tanaka, M.
Partner: UNT Libraries Government Documents Department

Three dimensional field analysis for the AGS combined function magnets

Description: In order to study the particle trajectories in the fringe field of the AGS ring during the single bunch multiple extraction (or fast extraction) from the AGS to the muon g-2 experiment and to the RHIC, the magnetic field of the AGS combined function magnets were calculated b using the TOSCA program. The results are compared with the field maps of the previous measurements. The particle tracking is achieved by using the TOSCA program post-processor.
Date: January 1, 1993
Creator: Meng, W. & Tanaka, M.
Partner: UNT Libraries Government Documents Department

IMPACT OF MAGNETIC FIELD INTERFERENCE IN THE SNS RING.

Description: The modest size of the SNS accumulator ring and the use of short, large aperture magnets makes unavoidable the overlapping between the magnetic end fields of the quadrupoles with the adjacent multipole correctors. This interference effect can be quantified through magnetic field simulations and measurements. The impact to the beam dynamics is finally discussed.
Date: June 18, 2001
Creator: PAPAPHILIPPOU,Y.; LEE,Y.Y. & MENG,W.
Partner: UNT Libraries Government Documents Department

Amorphization of Zr/sub 3/Al by hydrogenation and subsequent electron irradiation

Description: 1-MeV electron irradiation of hydrogenated Zr/sub 3/Al (Zr/sub 3/AlH/sub 0.96/) at 10K is studied. A more than 20 fold reduction in the critical dose required for complete amorphization is observed for the hydrogenated specimen as compared to the un-hydrogenated Zr/sub 3/Al under identical irradiation conditions. 11 refs., 4 figs.
Date: December 1, 1988
Creator: Meng, W.J.; Koike, J.; Okamoto, P.R. & Rehn, L.E.
Partner: UNT Libraries Government Documents Department

Comparison of computer predictions and magnetic field measurements for an iron spectrometer magnet

Description: Three dimensional computer calculations using the Program TOSCA have been made for a complex-shaped iron magnet. Precision field measurements were made on this magnet in preparation for its installation in a new Low Energy Separated Beam for the post-Booster high proton intensity AGS at Brookhaven National Laboratory. Point-by-point direct comparisons for field values will be described encompassing the entire useful acceptance. The predictability of high order multipoles will be described, including the region of the magnet ends. Computer predicted focal properties will be compared with results of experimental data analysis. The method of measurement and analysis, as well as comments on the computer calculations will be described. Conclusions will be drawn on the accuracy of calculations with respect to higher order moments and the impact on future beam optical design and execution of three dimensional computer codes.
Date: June 1, 1993
Creator: Danby, G. T.; Jackson, J. W.; Meng, W. & Spataro, C.
Partner: UNT Libraries Government Documents Department

Magnetic flux shielding for the precision muon g-2 storage ring superconducting inflector

Description: The muon g-2 experiment (E821) at the AGS requires a precision in the magnetic field over muon orbit at the level of 0.1 ppM. Injection is done with a superconducting inflector involving a double cosine theta winding approximately cancels its fringe field. Nevertheless its residual field would effect the homogeneity of the storage ring magnetic field. A method of using a superconducting sheet surrounding the inflector to further reduce the fringe is being investigated. The experimental program to explore this technique is described and some test results are presented.
Date: June 1, 1993
Creator: Meng, W.; Sampson, W. B. & Suenaga, M.
Partner: UNT Libraries Government Documents Department

Magnetic flux shielding for the precision muon g-2 storage ring superconducting inflector

Description: A muon g-2 experiment (E821) at the AGS requires knowledge of the magnetic field over muon orbits at the level of 0.1 ppM. The superconducting inflector involves a double cosine theta winding; this design approximately cancels its fringe field. Nevertheless its residual field would effect the homogeneity of the storage ring magnetic field. A method of using a superconducting sheet surrounding the inflector to further reduce the fringe field was proposed by one of the authors, W. Meng. An experimental program to explore this technique is described. Part of the test results are presented.
Date: December 31, 1993
Creator: Danby, G. T.; Meng, W.; Sampson, W. B. & Woodle, K.
Partner: UNT Libraries Government Documents Department

Comparison of computer predictions and magnetic field measurements for an iron spectrometer magnet

Description: Three dimensional computer calculations using the Program TOSCA have been made for a complex-shaped iron magnet. Precision field measurements were made on this magnet in preparation for its installation in a new Low Energy Separated Beam for the post-Booster high proton intensity AGS at Brookhaven National Laboratory. Point-by-point direct comparisons for field values will be described encompassing the entire useful acceptance. The predictability of high order multipoles will be described, including the region of the magnet ends. Computer predicted focal properties will be compared with results of experimental data analysis. The method of measurement and analysis, as well as comments on the computer calculations will be described. Conclusions will be drawn on the accuracy of calculations with respect to higher order moments and the impact on future beam optical design and execution of three dimensional computer codes.
Date: January 1, 1993
Creator: Danby, G. T.; Jackson, J. W.; Meng, W. & Spataro, C.
Partner: UNT Libraries Government Documents Department

A LARGE APERTURE NARROW QUADROUPOLE FOR THE SNS ACCUMULATOR RING.

Description: The accumulator ring of the Spallation Neutron Source (SNS) is designed to accept high-intensity H{sup -} beam of 1 GeV kinetic energy from the injecting LINAC, and to accumulate, in a time interval of 1 msec, 2 x 10{sup 14} protons in a single bunch of 700 nsec. In order to optimize the effective straight-section spaces for beam-injection, extraction and collimation, we have minimized the width of the large aperture quadrupoles which are located in the same straight sections of the accumulator ring with the injection and extraction systems. By minimizing the width of the quadrupoles to {+-}40.4 cm, the beam-injection and extraction angles are lowered to 8.75{sup o} and 16.8{sup o} respectively. Further optimization of the narrow quadrupole, minimizes the strength of the dodecapole multipole component of the quadrupole, thus reducing the width of the 12pole structure resonance and allowing a larger tune space for stability of the circulating beam. In this paper we present results derived from magnetic field calculations of 2D and 3D modeling, and discuss the method of optimizing the size of the quadrupole and minimizing its dodecapole multipole component.
Date: June 3, 2002
Creator: TSOUPAS,N.; BRODOWSKI,J.; MENG,W.; WEI,J.; LEE,Y.Y. & TUOZZOLO,J.
Partner: UNT Libraries Government Documents Department

Small gap magnet prototype measurements for eRHIC

Description: In this paper we present the design and prototype measurement of small gap (5mm to 10 mm aperture) dipole and quadrupole for the future high energy ERL (Energy Recovery Linac). The small gap magnets have the potential of largely reducing the cost of the future electron-ion collider project, eRHIC, which requires a 10GeV to 30 GeV ERL with up to 6 energy recovery passes (3.8 km each pass). We also studied the sensitivity of the energy recovery pass and the alignment error in this small magnets structure and countermeasure methods.
Date: May 23, 2010
Creator: Hao, Y.; He, P.; Jain, A.; Mahler, G.; Meng, W.; Tuozzolo, J. et al.
Partner: UNT Libraries Government Documents Department

SNS RING INJECTION STRIPPED ELECTRON COLLECTION: DESIGN ANALYSIS AND TECHNICAL ISSUES.

Description: This paper describes the simulation studies on the motions of stripped electrons generated in the injection section of the Spallation Neutron Source (SNS) accumulator ring and the effective collection mechanism. Such studies are important for high intensity machines, in order to reduce beam loss and protect other components in the vicinity. The magnetic field is applied to guide electrons to a collector, which is located at the bottom of the beam vacuum chamber. Part of the study results with and without considering the interactions between electrons and materials are presented and discussed. The final engineering design of the electron collector (catcher). The electron multi-pacting induced by beam loss and residual gas ionization along the ring has been studied in detail [l]. In the SNS accumulator ring straight section, electrons are stripped from the injected H{sup -} beam through a carbon foil. These protons must make 1100 turns to be compressed from 1 ms Linac pulse into a 700 ns bunch with 2E14 protons. The stripped electrons will have the same initial velocity but twice the intensity (current) of the H{sup -} beam. In this paper, we report the studies on electrons, and the optimum design of the collector.
Date: May 16, 2005
Creator: LEE, Y.; MAHLER, G.; MENG, W.; RAPARIA, D.; WANG, L. & WEI, J.
Partner: UNT Libraries Government Documents Department

A laser-wire beam-energy and beam-profile monitor at the BNL linac

Description: In 2009 a beam-energy monitor was installed in the high energy beam transport (HEBT) line at the Brookhaven National Lab linac. This device measures the energies of electrons stripped from the 40mA H{sup -} beam by background gas. Electrons are stripped by the 2.0x10{sup -7}torr residual gas at a rate of {approx}1.5x10{sup -8}/cm. Since beam electrons have the same velocities as beam protons, the beam proton energy is deduced by multiplying the electron energy by m{sub p}/m{sub e}=1836. A 183.6MeV H{sup -} beam produces 100keV electrons. In 2010 we installed an optics plates containing a laser and scanning optics to add beam-profile measurement capability via photodetachment. Our 100mJ/pulse, Q-switched laser neutralizes 70% of the beam during its 10ns pulse. This paper describes the upgrades to the detector and gives profile and energy measurements.
Date: March 28, 2011
Creator: Connolly, R.; Degen, C.; DeSanto, L.; Meng, W.; Michnoff, R.; Minty, M. et al.
Partner: UNT Libraries Government Documents Department

Small gap magnets and vacuum chambers for eRHIC

Description: eRHIC[1][2][3], a future high luminosity electron-ion collider at Brookhaven National Laboratory (BNL), will add polarized electrons to the list of colliding species in RHIC. A 10-30 GeV electron energy recovery linac (ERL) will require up to six passes around the RHIC 3.8 km circumference. We are developing and testing small (5 mm) gap dipole and quadrupole magnets and vacuum chambers for cost-effective eRHIC passes [4]. We are also studying the sensitivity of eRHIC pass optics to magnet and alignment errors in such a small magnet structure. We present the magnetic and mechanical designs of the small gap eRHIC components and prototyping test progress.
Date: May 4, 2009
Creator: Meng,W.; Bengtsson, J.; Hao, Y.; Mahler, G.; Tuozzolo, J. & Litvinenko, V. N.
Partner: UNT Libraries Government Documents Department

FINAL TEST RESULTS FOR THE SNS RING DIPOLES.

Description: To meet the performance parameters of the Spallation Neutron Source (SNS) for high beam intensity with low losses, the compact accumulation ring will contain 32 sector dipoles with 1.44 m effective length and a large aperture, 170 mm. The magnets are built from potted coils and machined pieces of solid iron. When first assembled, the dipoles met the requirements for field uniformity but the rms variation of the integral transfer function (ITF) was much larger than design at both fields of interest, 1.11 T{center_dot}m and 1.33 T{center_dot}m, corresponding to proton energies of 1.0 GeV and 1.3 GeV respectively. Based on initial measurements, shims have been added to the return legs or poles, as appropriate, in order to bring the rms variation of the 1.0 GeV ITF to the specification, 0.01%. The value of the ITF rms variation at 1.3 GeV for the shimmed magnets is 0.033%. Sorting the magnets has significantly reduced the load on the correctors due to this ITF variation.
Date: May 12, 2003
Creator: WANDERER,P.; JACKSON,J.; JAIN,A.; LEE,Y.Y.; MENG,W.; PAPAPHILIPPOU,Y. et al.
Partner: UNT Libraries Government Documents Department

THE SNS RING DIPOLE MAGNETIC FIELD QUALITY.

Description: The large acceptance and compact size of the Spallation Neutron Source (SNS) ring implies the use of short, large aperture dipole magnets, with significant end field errors. The SNS will contain 32 such dipoles. We report magnetic field measurements of the first 16 magnets. The end field errors have been successfully compensated by the use of iron bumps. For 1.0 GeV protons, the magnets have been shimmed to meet the 0.01% specification for rms variation of the integral field. At 1.3 GeV, the rms variation is 0.036%. The load on the corrector system at 1.3 GeV will be reduced by the use of sorting.
Date: June 3, 2002
Creator: Wanderer, P.; Jackson, J.; Jain, A.; Lee, Y. Y.; Meng, W.; Papaphilippou, I. et al.
Partner: UNT Libraries Government Documents Department

Microstructure and mechanical properties of nanostructured Ti-Si-N coatings.

Description: We have synthesized a series of Ti-Si-N coatings with 0 to 20 at. % Si by high-density plasma-assisted vapor-phase deposition. Composition, structure, and atomic short-range order were characterized by Rutherford Backscattering Spectrometry (RBS), Transmission Electron Microscopy (TEM), {Theta}-2{Theta} X-ray Diffraction (XRD), and X-ray Absorption Near Edge Structure (XANES) spectroscopy. The mechanical properties of these coatings were characterized by instrumented nanoindentation, and compared to those of B1-TiN. Our experiments show that the present series of Ti-Si-N coatings are nanocomposites, consisting of a nm-scale mixture of crystalline titanium nitride (TiN) and amorphous silicon nitride (a-Si:N). The mechanical response of the present series of Ti-Si-N coatings was found to be essentially independent of the Si composition, and similar to that of B1-TiN.
Date: April 18, 2002
Creator: Meng, W.J.; Zhang, X.D.; Shi, B.; Jiang, J.C.; Rehn, L.E.; Baldo, P.M. et al.
Partner: UNT Libraries Government Documents Department

RHIC Spin Flipper Commissioning Status

Description: The commissioning of the RHIC spin flipper in the RHIC Blue ring during the RHIC polarized proton run in 2009 showed the detrimental effects of global vertical coherent betatron oscillation induced by the 2-AC dipole plus 4-DC dipole configuration. This global orbital coherent oscillation of the RHIC beam in the Blue ring in the presence of collision modulated the beam-beam interaction between the two RHIC beams and affected Yellow beam polarization. The experimental data at injection with different spin tunes by changing the snake current also demonstrated that it was not possible to induce a single isolated spin resonance with the global vertical coherent betatron oscillation excited by the two AC dipoles. Hence, a new design was proposed to eliminate the coherent vertical betatron oscillation outside the spin flipper by adding three additional AC dipoles. This paper presents the experimental results as well as the new design.
Date: May 23, 2010
Creator: Bai, M.; Meot, F.; Dawson, C.; Oddo, P.; Pai, C.; Pile, P. et al.
Partner: UNT Libraries Government Documents Department

Dynamically tuned high-Q AC-dipole implementation

Description: AC-dipole magnets are typically implemented as a parallel LC resonant circuit. To maximize efficiency, it's beneficial to operate at a high Q. This, however, limits the magnet to a narrow frequency range. Current designs therefore operate at a low Q to provide a wider bandwidth at the cost of efficiency. Dynamically tuning a high Q resonant circuit tries to maintain a high efficiency while providing a wide frequency range. The results of ongoing efforts at BNL to implement dynamically tuned high-Q AC dipoles will be presented.
Date: May 2, 2010
Creator: Oddo, P.; Bai, M.; Dawson, W.C.; Meng, W.; Mernick, K.; Pai, C. et al.
Partner: UNT Libraries Government Documents Department

Beam-energy and laser beam-profile monitor at the BNL LINAC

Description: We are developing a non-interceptive beam profile and energy monitor for H{sup -} beams in the high energy beam transport (HEBT) line at the Brookhaven National Lab linac. Electrons that are removed from the beam ions either by laser photodetachment or stripping by background gas are deflected into a Faraday cup. The beam profile is measured by stepping a narrow laser beam across the ion beam and measuring the electron charge vs. transverse laser position. There is a grid in front of the collector that can be biased up to 125kV. The beam energy spectrum is determined by measuring the electron charge vs. grid voltage. Beam electrons have the same velocity as the beam and so have an energy of 1/1836 of the beam protons. A 200MeV H{sup -} beam yields 109keV electrons. Energy measurements can be made with either laser-stripped or gas-stripped electrons.
Date: May 2, 2010
Creator: Connolly, R.; Briscoe, B.; Degen, C.; DeSanto, L.; Meng, W.; Minty, M. et al.
Partner: UNT Libraries Government Documents Department

ATOMIC BEAM POLARIZATION MEASUREMENT OF THE RHIC POLARIZED H-JET TARGET.

Description: The RHIC polarized H-Jet measures the polarization of the RHIC proton beam via elastic scattering off a nuclear polarized atomic hydrogen beam. The atomic beam is produced by a dissociator, a beam forming system and sextupole magnets. Nuclear polarization is achieved by exchanging occupation numbers of hyperfine states using high frequency transitions. The polarization was measured using a modified form of a Breit-Rabi polarimeter including focusing magnets and another set of high frequency transitions. The sampling of a large part of the beam and low noise electronics made it possible to measure the polarization to a high degree of accuracy in a very short time period (1 min). Using this system, we measured no depolarization of the atomic beam due to the RF fields of the bunched proton beam. Time-of-Flight measurements were done using a fast chopper and a QMA at the position of the RHIC interaction point to determine the areal density of the atomic beam seen by the RHIC beam.
Date: January 28, 2005
Creator: Makdisi, Y.; Nass, A.; Graham, D.; Kponou, A.; Mahler, G.; Meng, W. et al.
Partner: UNT Libraries Government Documents Department