Abstracts Brochure - CERN

TUPCH — Poster Session 27-Jun-06 16:00 - 18:00
*A. M. Tron and I. G. Merinov. Method of bunch radiation photochronography with 10 femtosecond and less
resolution. http://www.physics.ucla.edu/PAHBEB2005/talks/10oct2005/wg2/atron.pdf
Study of Beam Energy Spread at VEPP-4M
The knowledge of beam energy spread is
necessary for the experimental program of
VEPP-4M collider. In this report we discuss
the application of optical diagnostics for
O.I. Meshkov, V. F. Gurko, A.D. Khilchenko, V. Kiselev, N.Yu.
Muchnoi, A.N. Selivanov, A. N. Zhuravlev (BINP SB RAS)
measurement of this value. The diagnostics is based on multi-anode photomultiplier and provides information about
betatron and synchrotron 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.
Fast and Precise Beam Energy Monitor Based on the Compton Backscattering at the VEPP-
4M Collider
Accurate knowledge of the colliding beam
energies is essential for the current experi- N.Yu. Muchnoi, S.A. Nikitin, V.N. Zhilich (BINP SB RAS)
ments with the 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 energy monitor with accuracy about 50 keV within a 10 to 30 min measurement cycle
was created. Carbon dioxide laser radiation is scattered on the electron beam; the backscattered photons are detected
by the HPGe detector. The upper edge of the photon energy spectrum contains information about the average energy
of electrons in the beam and the beam energy spread. This system was 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 allows one to measure the electron beam energy spread. This
report describes the system configuration and performance.
Dependence of the Electron Beam Polarization Effect in the Intra-beam Scattering Rate on
the Vertical Beam Emittance
Measurement of the Intra-beam scattering
rate is applied in the resonant depolariza- S.A. Nikitin, I.B. Nikolaev (BINP SB RAS)
tion 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 onedimensional
approach, we calculate the magnitude of jump subject to, among other things, the vertical component
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