Showing papers by "Konstantin Beloborodov published in 2009"

High density aerogel for ASHIPH SND—test results

Abstract: The paper is devoted to the cosmic tests of particle identification system for the SND detector at VEPP-2000. The goal of the tests is to measure main parameters of the system: average signal for the relativistic particles, nonuniformity of the light collection, and time resolution. The measurements of the average signal were done in five points of the counter. The obtained value of the signal is about 10 photoelectrons. The time resolution is about 2 ns. The time dependence of the average amplitude was measured also. It was shown that average amplitude of the signal decreases with characteristic time of about two years. The cause of the signal decrease is discussed.

Study of the process e+e- →μ+μ- in the energy region √s = 980,1040-1380 MeV

Abstract: The cross section of the process e{sup +}e{sup -}{yields}{mu}{sup +}{mu}{sup -} was measured in the spherical neutral detector experiment at the VEPP-2M e{sup +}e{sup -} collider in the energy region {radical}(s)=980, 1040-1380 MeV. The event numbers of the process e{sup +}e{sup -}{yields}{mu}{sup +}{mu}{sup -} were normalized to the integrated luminosity measured using e{sup +}e{sup -}{yields}e{sup +}e{sup -} and e{sup +}e{sup -}{yields}{gamma}{gamma} processes. The ratio of the measured cross section to the theoretically predicted value is 1.006{+-}0.007{+-}0.016 and 1.005{+-}0.007{+-}0.018 in the first and second case, respectively. Using results of the measurements, the electromagnetic running coupling constant {alpha} in the energy region {radical}(s)=1040-1380 MeV was obtained =134.1{+-}0.5{+-}1.2 and this is in agreement with theoretical expectation.