Yu-chiu Chao - Academia.edu (original) (raw)
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Papers by Yu-chiu Chao
Proceedings of the 2005 Particle Accelerator Conference, 2005
The optics of the newly commissioned LHC beam transfer line TI 8 was studied with beam trajectori... more The optics of the newly commissioned LHC beam transfer line TI 8 was studied with beam trajectories, dispersion and profile measurements. Steering magnet response measurements were used to analyze the quality of the steering magnets and of the beam position monitors. A simultaneous fit of the quadrupole strengths was used to search for setting or calibration errors. Residual coupling between the planes was evaluated using high statistics samples of trajectories. Initial conditions for the optics at the entrance of the transfer line were reconstructed from beam profile measurements with Optical Transition Radiation monitors. The paper presents the various analysis methods and their errors. The expected emittance growth arising from optical mismatch into the LHC is evaluated.
Physical Review Letters, Nov 9, 2012
Physical Review Letters, 2012
The parity-violating (PV) asymmetry of inclusive π − production in electron scattering from a liq... more The parity-violating (PV) asymmetry of inclusive π − production in electron scattering from a liquid deuterium target was measured at backward angles. The measurement was conducted as a part of the G0 experiment, at a beam energy of 360 MeV. The physics process dominating pion production for these kinematics is quasi-free photoproduction off the neutron via the ∆ 0 resonance. In the context of heavy-baryon chiral perturbation theory (HBχPT), this asymmetry is related to a low energy constant d − ∆ that characterizes the parity-violating γN∆ coupling. Zhu et al. calculated d − ∆ in a model benchmarked by the large asymmetries seen in hyperon weak radiative decays, and predicted potentially large asymmetries for this process, ranging from A − γ = −5.2 to +5.2 ppm. The measurement performed in this work leads to A − γ = −0.36 ± 1.06 ± 0.37 ± 0.03 ppm (where sources of statistical, systematic and theoretical uncertainties are included), which would disfavor enchancements considered by Zhu et al. proportional to V ud /Vus. The measurement is part of a program of inelastic scattering measurements that were conducted by the G0 experiment, seeking to determine the N − ∆ axial transition form-factors using PV electron scattering.
TRIUMF is collaborating with VECC on the design of a 10 MeV injector cryomodule to be used as a f... more TRIUMF is collaborating with VECC on the design of a 10 MeV injector cryomodule to be used as a front end for a high intensity electron linac. A electron gun and low energy beam transport (LEBT) have been installed in a test area to act as the injector for the cryomodule test. The LEBT includes a wide variety of diagnostics to fully characterize the beam from the gun. A series of beam tests are being conducted during the stage installation. The test configuration details and results of beam tests will be presented.
Proceedings of the 2005 Particle Accelerator Conference, 2005
The optics of the newly commissioned LHC beam transfer line TI 8 was studied with beam trajectori... more The optics of the newly commissioned LHC beam transfer line TI 8 was studied with beam trajectories, dispersion and profile measurements. Steering magnet response measurements were used to analyze the quality of the steering magnets and of the beam position monitors. A simultaneous fit of the quadrupole strengths was used to search for setting or calibration errors. Residual coupling between the planes was evaluated using high statistics samples of trajectories. Initial conditions for the optics at the entrance of the transfer line were reconstructed from beam profile measurements with Optical Transition Radiation monitors. The paper presents the various analysis methods and their errors. The expected emittance growth arising from optical mismatch into the LHC is evaluated.
Physical Review Letters, Nov 9, 2012
Physical Review Letters, 2012
The parity-violating (PV) asymmetry of inclusive π − production in electron scattering from a liq... more The parity-violating (PV) asymmetry of inclusive π − production in electron scattering from a liquid deuterium target was measured at backward angles. The measurement was conducted as a part of the G0 experiment, at a beam energy of 360 MeV. The physics process dominating pion production for these kinematics is quasi-free photoproduction off the neutron via the ∆ 0 resonance. In the context of heavy-baryon chiral perturbation theory (HBχPT), this asymmetry is related to a low energy constant d − ∆ that characterizes the parity-violating γN∆ coupling. Zhu et al. calculated d − ∆ in a model benchmarked by the large asymmetries seen in hyperon weak radiative decays, and predicted potentially large asymmetries for this process, ranging from A − γ = −5.2 to +5.2 ppm. The measurement performed in this work leads to A − γ = −0.36 ± 1.06 ± 0.37 ± 0.03 ppm (where sources of statistical, systematic and theoretical uncertainties are included), which would disfavor enchancements considered by Zhu et al. proportional to V ud /Vus. The measurement is part of a program of inelastic scattering measurements that were conducted by the G0 experiment, seeking to determine the N − ∆ axial transition form-factors using PV electron scattering.
TRIUMF is collaborating with VECC on the design of a 10 MeV injector cryomodule to be used as a f... more TRIUMF is collaborating with VECC on the design of a 10 MeV injector cryomodule to be used as a front end for a high intensity electron linac. A electron gun and low energy beam transport (LEBT) have been installed in a test area to act as the injector for the cryomodule test. The LEBT includes a wide variety of diagnostics to fully characterize the beam from the gun. A series of beam tests are being conducted during the stage installation. The test configuration details and results of beam tests will be presented.