Nikitin, S.A.

Paper	Title	Page
TUPCH074	Fast and Precise Beam Energy Monitor Based on the Compton Backscattering at the VEPP-4M Collider	1181
	N.Yu. Muchnoi, S.A. Nikitin, V.N. Zhilich BINP SB RAS, Novosibirsk
	Accurate knowledge of the colliding beam energies is essential for the current experiments with the KEDR \cite{KEDR} detector at the VEPP-4M collider. Now the experimental activity is focused on the new precise measurement of the tau-lepton mass by studying the behavior of the tau production cross-section near the reaction threshold. To achieve the desired quality of the experiment, an on-line beam energy monitoring by the Compton backscattering of laser light was performed. This approach is found to be a very good supplement to rare energy calibrations by the resonant depolarization technique, saving the beam time for luminosity runs. The method itself does not require electron beam polarization and additionally allows one to measure the electron beam energy spread. The achieved accuracy of the method in the beam energy range 1.7–1.9 GeV is 60 keV.
TUPCH075	Dependence of the Electron Beam Polarization Effect in the Intra-beam Scattering Rate on the Vertical Beam Emittance	1184
	S.A. Nikitin, I.B. Nikolaev BINP SB RAS, Novosibirsk
	Measurement of the Intra-beam scattering rate is applied in the resonant depolarization technique to detect beam polarization in electron/positron storage rings. A depolarization jump in the counting rate of scattering particles occurs at the instant when the beam becomes unpolarized due to fulfillment of the external spin resonance condition. The magnitude of the jump depends on polarization quadratically. It also depends on some other beam parameters as well as the position of counters relative to the beam orbit. A larger jump implies higher accuracy in absolute calibration of particle energy because the latter is proportional to the spin precession frequency. In contrast to an ordinary one-dimensional approach, we calculate the magnitude of jump subject to, among other things, the vertical component of relative velocity in particle collisions inside the beam. For this purpose, the transverse momentum distribution function is properly modified. Calculations performed for the VEPP-4M storage ring-collider show that the jump may depend significantly on the ratio between the vertical and radial beam emittance. We present results of our recent experiments on study of this dependence.
WEPCH086	Adiabatic Theory of Slow Extraction of Particles from a Synchrotron	2119
	S.A. Nikitin BINP SB RAS, Novosibirsk
	An analytical approach is developed to describe the process of slow extraction of particles from a synchrotron based on adiabatic crossing of the betatron resonance of the third order. An exact expression for the phase integral is found to analyze the conditions of oscillation amplitude growth near the resonance band. It allows one to directly define the interval of adiabatic motion from the start of decreasing the resonant tune to the beginning of fast increase of the oscillation amplitude. The interval distribution function is constructed for the cases of zero momentum spread and zero machine chromaticity as well as for the general case, taking into account non-zero momentum spread, non-zero chromaticity and synchrotron oscillations. Some numeric calculations of the time dependence of the extracted particle current are presented. It is shown that the momentum spread in the extracted beam can be minimized with the use of additional RF acceleration of particles during the slow extraction procedure.
THOBFI03	Record-high Resolution Experiments on Comparison of Spin Precession Frequencies of Electron Bunches Using the Resonant Depolarization Technique in the Storage Ring	2787
	S.A. Nikitin, O. Anchugov, V.E. Blinov, A. Bogomyagkov, V.P. Cherepanov, G.V. Karpov, V. Kiselev, E. Levichev, I.B. Nikolaev, A.A. Polunin, E. Shubin, E.A. Simonov, V.V. Smaluk, M.V. Struchalin, G.M. Tumaikin BINP SB RAS, Novosibirsk
	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.
	Transparencies
MOPLS028	DAFNE Status Report	604
	A. Gallo, D. Alesini, M.E. Biagini, C. Biscari, R. Boni, M. Boscolo, B. Buonomo, A. Clozza, G.O. Delle Monache, E. Di Pasquale, G. Di Pirro, A. Drago, A. Ghigo, S. Guiducci, M. Incurvati, P. Iorio, C. Ligi, F. Marcellini, C. Marchetti, G. Mazzitelli, C. Milardi, L. Pellegrino, M.A. Preger, L. Quintieri, R. Ricci, U. Rotundo, C. Sanelli, M. Serio, F. Sgamma, B. Spataro, A. Stecchi, A. Stella, S. Tomassini, C. Vaccarezza, M. Vescovi, M. Zobov INFN/LNF, Frascati (Roma) G. Benedetti CELLS, Bellaterra (Cerdanyola del Vallès) L. Falbo INFN-Pisa, Pisa J.D. Fox, P. Raimondi, D. Teytelman SLAC, Menlo Park, California E. Levichev, S.A. Nikitin, P.A. Piminov, D.N. Shatilov BINP SB RAS, Novosibirsk
	The operation of DAFNE, the 1.02 GeV c.m. e+e- collider of the Frascati National Laboratory with the KLOE detector, started in April 2004 has been concluded at the end of March 2006 with a total delivered luminosity of 2 fb-1 on the peak of the Phi resonance, 0.2 fb-1 off peak and a high statistics scan of the resonance. The best performances of the collider during this run have been a peak luminosity of 1.5 1032 cm-2s-1 and a daily delivered luminosity of 10 pb-1. The KLOE detector has been removed from one of the two interaction regions and its low beta section substituted with a standard magnetic structure, allowing for an easy vertical separation of the beams, while the FINUDA detector has been moved onto the second interaction point. Several improvements on the rings have also been implemented and are described together with the results of machine studies aimed at improving the collider efficiency and testing new operating conditions.
MOPLS038	Beam Energy Calibration in Experiment on Precise Tau Lepton Mass Measurement at VEPP-4M with KEDR Detector	625
	A. Bogomyagkov, V.E. Blinov, S. Karnaev, V. Kiselev, E.V. Kremyanskaya, E. Levichev, O.I. Meshkov, S.I. Mishnev, I. Morozov, N.Yu. Muchnoi, S.A. Nikitin, I.B. Nikolaev, A.G. Shamov, D.N. Shatilov, E.A. Simonov, A.N. Skrinsky, V.V. Smaluk, Yu.A. Tikhonov, G.M. Tumaikin, V.N. Zhilich BINP SB RAS, Novosibirsk
	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.