Paper | Title | Page |
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MOPLS038 | Beam Energy Calibration in Experiment on Precise Tau Lepton Mass Measurement at VEPP-4M with KEDR Detector | 625 |
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Experiment on mass measurement of tau lepton requires an absolute energy calibration. The resonant depolarization technique is used for most accurate (1 keV) but once at a time energy calibration. The measured energy is used for calibration of the germanium detector for Compton backscattering energy monitoring. The developed Compton backscattering facility allows continuous energy monitoring with accuracy of 50 keV for 10 minutes of data acquisition. The tau lepton threshold is in the vicinity of integer spin resonance, which minimizes polarization lifetime in the presence of vertical orbit distortions. Therefore, spin matching of the VEPP-4M is required. The achieved lifetime is sufficient for absolute energy calibration. | ||
TUPCH073 | Study of Beam Energy Spread at the VEPP-4M | 1178 |
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The knowledge of beam energy spread is necessary for the experimental program of the VEPP-4M collider. In this report we discuss the application of optical diagnostics for measurement of this value. The diagnostics is based on multi-anode photomultiplier and provides information about betatron and betetron frequencies of electron beam*. The beam energy spread is derived from the spectra of synchrotron oscillation. The results, obtained with this method, are compared with data, provided by Compton backscattering technique.
*O. I. Meshkov et al. Application of the beam profile monitor for VEPP-4M tuning. Proc. of DIPAC '05, June 6 - 8, 2005, Lyon, France, POM008. |
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THOBFI03 | Record-high Resolution Experiments on Comparison of Spin Precession Frequencies of Electron Bunches Using the Resonant Depolarization Technique in the Storage Ring | 2787 |
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The opportunity of performing an experiment on high precision comparison of the electron and positron anomalous magnetic moments following the VEPP-2M experiment is under study at the VEPP-4M storage ring. The record accuracy of 2x10-8 was obtained for comparison of spin precession frequencies in the experiment on resonant depolarization with simultaneously circulating electron bunches, two of them polarized and one unpolarized. It is the first time when the spreading of the spin precession frequency line (~5x10-7,) due to scattering of particle trajectories about the equilibrium orbit in a non-linear field of the storage ring, was presumably observed in experiments. We proposed and realized an RF scheme for controlled separation of the spin precession frequencies of two electron bunches; the first measurements using this scheme were made. | ||
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