(in MAD-8 format)
The VEPP-4 electron-positron collider with the maximal beam energy of 6 GeV has been commissioned in 1979. In 1979-1985, a range of high-energy physics experiments with the MD-1 detector has been performed, including ypsilon-meson study and two-photon physics. To increase the collider luminosity, a modernization has been done in 1986-1994.
Principal modifications of the VEPP-4M against the VEPP-4:
The VEPP-4M layout in the PDF format is here.
|Revolution frequency||818.924 kHz|
|Beam energy||1.5-5.5 GeV|
|Momentum compaction factor||0.0168|
|Betatron tunes, horizontal/vertical||8.54/7.58|
|Natural chromaticity, horizontal/vertical||-14.5/-20.3|
|Aperture in semi-rings||60x30 mm2|
|Accelerating RF system|
|Number of cavities||5|
|Maximal amplitude voltage per cavity||1000 kV|
|Maximal RF generator power||700 kW|
|Design beam parameters (E = 1850 MeV)|
|Damping time of
ver. betatron oscillation
hor. betatron oscillation
|Horizontal emittance||24.6 nm·rad|
|Energy spread dE/E, r.m.s.||3.22·10-4|
|Bunch length, r.m.s.||3 см|
|Energy loss per turn||32 keV|
|Synchrotron tune||0.011 (9.26 kHz)|
At present, the main high-energy physics experiment at the VEPP-4M is precise measurement of the tau-lepton mass at its production threshold. Experiments for accuracy improvement of the measured masses of the psi(2s) and psi(3770) mesons are also continued (the beam energy range is 1840-1900 MeV). In the low energy range (1.5-3.0 GeV), peak luminosity of the collider is 2·1030cm-2s-1. Average rate of KEDR data collection is about 300 nb-1 per week.
Design luminosity at the 6 GeV energy is 4·1031cm-2s-1 with natural beam size; 7·1031см-2с-1 with superconducting damping wigglers; 1032см-2с-1 with additional superconducting RF cavity to decrease bunch length and beta-fuction at the interaction point.