The general purpose spherical nonmagnetic detector (SND) is now taking data at VEPP-2M e
+e
− collider in BINP (Novosibirsk) in the center-of-mass-energy range of 0.2 – 1.4 GeV. The energy ...calibration of the NaI(Tl) calorimeter of the SND detector with cosmic muons is described. Using this method, the energy resolution of 5.5% (σ) for 500 MeV photons was achieved.
The process e(+)e(-)-->mu(+)mu(-) has been studied by the SND detector at the VEPP-2M e(+)e(-) collider in the phi(1020)-resonance energy region. The measured effective phi meson leptonic branching ...ratio B(phi-->l(+)l(-)) identical with square root of B(phi-->e(+)e(-))B(phi-->mu(+)mu(-)) = (2.89 +/- 0.10 +/- 0.06) x 10(-4) agrees well with the Particle Data Group value B(phi-->e(+)e(-)) = (2.91 +/- 0.07) x 10(-4), confirming mu-e universality. Without additional assumption of mu-e universality the branching ratio B(phi-->mu(+)mu(-)) = (2.87 +/- 0.20 +/- 0.14) x 10(-4) was obtained.
Axially oriented crystals, penetrated by high-energy electrons, are powerful photon sources and, hence, intense positron sources. Such kinds of positron sources have been studied experimentally at ...CERN, with the tertiary electron beam of the SPS having an energy of 6 and 10 GeV. Four and eight millimeters thick tungsten crystals and a compound target made of a 4 mm crystal followed by a 4 mm amorphous disk were used with an orientation along the
〈1
1
1〉
axis. The positrons were detected by a drift chamber, partially immersed in a magnetic field. The reconstructed trajectories allowed the determination of their energy and angular spectra. Significant enhancements were observed for the crystal source when compared to the amorphous one. The gain was about 3 for the 4 mm target and about 2 for the 8 mm and the compound targets. These preliminary results are described after short presentations of the experimental set-up and of the method of track reconstruction.
The converters were designed for generation of intensive bremsstrahlung radiation. The powerful electron beam (5
MeV, 50
kW) was generated by ILU-10 accelerator. The converters differ in technology ...of manufacturing and material of target, tungsten carbide or tantalum. The aluminum board with the channels for cooling water is used as the base of the converter and filter for low energy part of bremsstrahlung spectrum. The converters can be installed in vacuum or outside the accelerator in air under the beam window. The results of testing of different converters are given.
The results of the investigation of lidar sounding to measure the spacetime distribution of the optical characteristics in oceanic light scattering layers are presented. The shipborne lidar used in ...the experiments excluded sea-state influences on the sounding results. Such an approach allowed the investigation of dynamic processes in the upper ocean layer. Experimental data for internal wave registration are also given.
The e{sup +}e{sup -} {sup {yields}} {omega}, {rho} {sup {yields}} {pi}{sup 0}e{sup +}e{sup -} processes have been investigated in the experiments with Spherical Neutral Detector at the VEPP-2M e{sup ...+}e{sup -} collider. The measurements provide the probability B({omega} {sup {yields}} {pi}{sup 0}e{sup +}e{sup -}) = (0.761 {+-} 0.053 {+-} 0.064) x 10{sup -3} of the {omega} {sup {yields}} {pi}{sup 0}e{sup +}e{sup g-} conversion decay and the upper limit B({rho} {sup {yields}} {pi}{sup 0}e{sup +}e{sup -}) < 1.2 x 10{sup -5} (at 90% CL) for the {rho} {sup {yields}} {pi}{sup 0}e{sup +}e{sup -} decay. The transition form factor was measured at three values of the 4-momentum transfer squared.
The results of lidar observations of stratospheric aerosol perturbations for the period of July–November 2008 at three lidar stations of the CIS-LiNet network in Tomsk, Minsk, and Vladivostok are ...presented along with the results obtained in the Gobi Desert during a research expedition. The behavior of stratospheric profiles of the scattering ratio
R
(
H
) (ratio of the total aerosol and molecular backscattering coefficient to the molecular backscattering coefficient) is analyzed at different wavelengths characterizing the aerosol stratification in the stratosphere. The transport of air masses in the stratosphere is studied by the method of direct and backward trajectories using the NOAA HYSPLIT model. It is shown that stratospheric aerosol perturbations are connected with explosive eruptions of volcanoes of the Aleutian islands Okmok (53.4° N, 168.1° W; July 12, 2008) and Kasatochi (52.2° N, 175.5° W; August 6–8, 2008).
The conversion decays
φ→
ηe
+
e
− and
η→
γe
+
e
− were studied by the SND detector using
φ-meson production in
e
+
e
−-annihilation at VEPP-2M collider. The branching ratios of these decays were ...measured:
Br(
φ→
ηe
+
e
−)=(1.19±0.19±0.07)×10
−4 and
Br(
η→
γe
+
e
−)=(5.15±0.62±0.39)×10
−3. The
e
+
e
−-pair mass spectra and transition form factors were also studied.
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