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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

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

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: 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

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

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

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

Laser-based profile and energy monitor for H beams

Description: A beam profile and energy monitor for H{sup -} beams based on laser photoneutralization was built at Brookhaven National Laboratory (BNL)* for use on the High Intensity Neutrino Source (HMS) at Fermilab. An H{sup -} ion has a first ionization potential of 0.75eV and can be neutralized by light from a Nd:YAG laser ({lambda}=1064nm). To measure beam profiles, a narrow laser beam is stepped across the ion beam, removing electrons from the portion of the H{sup -} beam intercepted by the laser. These electrons are channeled into a Faraday cup by a curved axial magnetic field. To measure the energy distribution of the electrons, the laser position is fixed and the voltage on a screen in front of the Faraday cup is raised in small steps. We present a model which reproduces the measured energy spectrum from calculated beam energy and space-charge fields. Measurements are reported from experiments in the BNL linac MEBT at 750keV.
Date: September 29, 2008
Creator: Connolly, R.; Alessi, J.; Bellavia, S.; Dawson, C.; Degen, C.; Meng, W. et al.
Partner: UNT Libraries Government Documents Department

UNIQUE FEATURES IN MAGNET DESIGNS FOR R AND D ENERGY RECOVERY LINAC AT BNL.

Description: In this paper we describe the unique features and analysis techniques used on the magnets for a R&D Energy Recovery Linac (ERL) [1] under construction at the Collider Accelerator Department at BNL. The R&D ERL serves as a test-bed for future BNL ERLs, such as an electron-cooler-ERL at RHIC [2] and a future 20 GeV ERL electron-hadron at eRHIC [3]. Here we present select designs of various dipole and quadruple magnets which are used in Z-bend merging systems [4] and the returning loop, 3-D simulations of the fields in aforementioned magnets, particle tracking analysis, and the magnet's influence on beam parameters. We discuss an unconventional method of setting requirements on the quality of magnetic field and transferring them into measurable parameters as well as into manufacturing tolerances. We compare selected simulation with results of magnetic measurements. A 20 MeV R&D ERL (Fig. 1) is in an advanced phase of construction at the Collider-Accelerator Department at BNL, with commissioning planned for early 2009. In the R&D ERL, an electron beam is generated in a 2 MeV superconducting RF photo-gun, next is accelerated to 20 MeV in a 5 cell SRF linac, subsequently passed through a return loop, then decelerated to 2 MeV in the SRF linac, and finally is sent to a beam dump. The lattice of the R&D ERL is designed with a large degree of flexibility to enable the covering of a vast operational parameter space: from non-achromatic lattices to achromatic with positive, zero and negative R56 parameter. It also allows for large range tunability of Rlz and lattice RS4 parameters (which are important for transverse beam-break-up instability). Further details of the R&D ERL can be found elsewhere in these proceedings [5]. The return loop magnets are of traditional design with the following exceptions: (a) The bending radius of ...
Date: June 25, 2007
Creator: MENG,W.; JAIN, A.; GANETIS, G.; KAYRAN, D.; LITVINENKO, V.N.; LONGO, C. et al.
Partner: UNT Libraries Government Documents Department

Relativistic Heavy Ion Collider spin flipper commissioning plan

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 lifetime. 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, RHIC spin flipper was re-designed 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: September 27, 2010
Creator: Bai, M.; Dawson, C.; Makdisi, Y.; Meng, W.; Meot, F.; Oddo, P. et al.
Partner: UNT Libraries Government Documents Department

STATUS OF FAST IR ORBIT FEEDBACK AT RHIC.

Description: To compensate modulated beam-beam offsets caused by mechanical vibrations of IR triplet quadrupoles at frequencies around 10 Hz, a fast IR orbit feedback system has been developed. We report design considerations and recent status of the system.
Date: June 26, 2006
Creator: MONTAG, C.; CUPOLO, J.; GLENN, J.; LITVINENKO, V.; MARUSIC, A.; MENG, W. et al.
Partner: UNT Libraries Government Documents Department

MEASUREMENTS AND MODELING OF EDDY CURRENT EFFECTS IN BNL'S AGS BOOSTER.

Description: Recent beam experiments at BNL's AGS Booster have enabled us to study in more detail the effects of eddy currents on the lattice structure and our control over the betatron tune. The Booster is capable of operating at ramp rates as high as 9 T/sec. At these ramp rates eddy currents in the vacuum chambers significantly alter the fields and gradients seen by the beam as it is accelerated. The Booster was designed with these effects in mind and to help control the field uniformity and linearity in the Booster Dipoles special vacuum chambers were designed with current windings to negate the affect of the induced eddy currents. In this report results from betatron tune measurements and eddy current simulations will be presented. We will then present results from modeling the accelerator using the results of the magnetic field simulations and compare these to the measurements.
Date: June 23, 2006
Creator: BROWN, K.A.; AHRENS, L.; GARDNER, C.; GLENN, J.W.; HARVEY, M.; MENG, W. 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