The system for insertion of a laser beam into the vacuum chamber of high-energy storage ring is described. The main part of the system is the high-vacuum viewport for the IR radiation, based on ZnSe or GaAs crystals. The design of the viewports is presented.
The review of using of compton backscattering method for determination of the beam energy in collider experiments is given.
The beam energy measurement system for the VEPP-2000 electron-positron collider is described. The method of Compton backscattering of $CO$ laser photons on the electron beam is used. The relative systematic uncertainty of the beam energy determinatio
n is estimated as 6cdot10^{-5}. It was obtained through comparison of the results of the beam energy measurements using the Compton backscattering and resonance depolarization methods.
The beam energy measurement system (BEMS) for the upgraded Beijing electron-positron collider BEPC-II is described. The system is based on measuring the energies of Compton back-scattered photons. The relative systematic uncertainty of the electron a
nd positron beam energy determination is estimated as 2 cdot 10^{-5}. The relative uncertainty of the beams energy spread is about 6 %.
The search for lepton-flavor-violation process e^+e^-to emu in the energy region sqrt{s}=984 - 1060 MeV with SND detector at VEPP-2M e^+e^- collider is reported. The model independent 90% CL upper limits on the e^+e^-to emu cross section, sigma_{emu}
< 11 pb, as well as on the corresponding phito emu branching fraction, B(phito emu) < 2 times 10^{-6}, for the final particles polar angles 55^circ<theta<125^circ, were obtained.
The cross section of the process e+e-tomu+mu- was measured in the SND experiment at the VEPP-2M e+e- collider in the energy region sqrt{s}=980, 1040 -- 1380 MeV. The event numbers of the process e+e-tomu+mu- were normalized to the integrated luminosi
ty measured using e+e-to e+e- and e+e-togammagamma processes. The ratio of the measured cross section to the theoretically predicted value is 1.006pm 0.007 pm 0.016 and 1.005 pm 0.007 pm 0.018 in the first and second case respectively. Using results of the measurements, the electromagnetic running coupling constant alpha in the energy region sqrt{s}=1040 -- 1380 MeV was obtained <1/alpha> = 134.1pm 0.5 pm 1.2 and this is in agreement with theoretical expectation.
This document contains a proposal of the BEPC-II collider beam energy calibration system (IHEP, Beijing). The system is based on Compton backscattering of carbon dioxide laser radiation, producing a beam of high energy photons. Their energy spectrum
is then accurately measured by HPGe detector. The high-energy spectrum edge will allow to determine the average electron or positron beam energy with relative accuracy about 3x10^-5.
