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 determination is estimated as 610 super(-5). It was obtained through comparison of the results of the beam energy measurements using the Compton backscattering and resonance depolarization methods.
We studied the effect of the purinergic signaling system and the contribution of Cl
–
transporters to isosmotic contraction of vascular smooth muscle cells (SMC), which results from the normalization ...of osmotic pressure after prolonged incubation in a hyposmotic medium. The study was carried out by myography of endothelium-denuded aortic ring segments of male Wistar rats. Isosmotic contraction was induced by placing vascular segments in normosmotic Krebs solution (120 mM NaCl) after a 40-minute incubation in a hyposmotic Krebs solution (40 mM NaCl). Purinergic receptors were activated by adenosine 5’-triphosphate (ATP, 500 µM), a nonselective P
2
X and P
2
Y receptor agonist, and uridine 5’-triphosphate (UTP, 500 µM), a selective P
2
Y receptor agonist. ATP and UTP abolished the transience of the aortic SMC isosmotic contraction without affecting its amplitude. Pretreatment of vascular segments with ATP and UTP during incubation in a hyposmotic solution completely suppressed the development of isosmotic contraction in the presence of ATP or UTP, but did not affect it without purinergic receptor activators. The Na
+
–K
+
–2Cl
–
-cotransporter (NKCC) inhibitor bumetanide (100 µM) abolished isosmotic contraction in the presence of ATP (not UTP) but restored its transience. The nonselective Cl
–
channel and Cl
–
/HCO
3
–
exchanger blocker DIDS (100 µM) suppressed the development of isosmotic contraction in the presence of both ATP and UTP. The potassium channel blocker tetraethylammonium (10 mM) potentiated the contractile activity of UTP toward isosmotic volume contraction. Presumably, purinergic receptors abolish the transience of isosmotic contraction by activating Cl
–
currents through activation of P
2
Y receptors. The mechanism of interaction between the purinergic signaling system and Cl
–
transport during cell volume changes requires further investigation.
Search for the process e + e − → η Achasov, M. N.; Barnyakov, A. Yu; Beloborodov, K. I. ...
Physical review. D,
09/2018, Letnik:
98, Številka:
5
Journal Article
Recenzirano
Odprti dostop
A search for the rare decay η→e+e− is performed using the inverse process e+e−→η in the decay mode η→π0π0π0. We analyze data with an integrated luminosity of 654 nb−1 accumulated at the VEPP-2000 ...e+e− collider with the SND detector at the center-of-mass energy E=mηc2≈548 MeV, and set the upper limit B(η→e+e−)<7×10−7 at the 90% confidence level.
Calibration of the calorimeter signal waveform in the SND detector Achasov, M.N.; Bogdanchikov, A.G.; Druzhinin, V.P. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
08/2019, Letnik:
936
Journal Article
Recenzirano
The new spectrometric channel for the Spherical Neutral Detector (SND) electromagnetic calorimeter (EMC) is described. It provides measurement of the calorimeter signal arrival time and amplitude ...with 1 ns and 250 keV resolutions, respectively. The new electronics is useful for reliable detection of low-speed anti-neutrons from the e+e−→nn̄ reaction near threshold and needed for increasing the EMC operation rate. The algorithm of determination of signal parameters (time, amplitude) is based on invariability of the signal waveform. We present the procedure of the waveform calibration using signals from cosmic-muon and Bhabha scattering events.
The development of the new spectrometric channel for the SND electromagnetic calorimeter is described. The time resolution of about 1 ns is achieved at an energy deposition in the calorimeter crystal ...of 100 MeV . The amplitude resolution is about 250 keV.
SND DAQ system evolution Bogdanchkov, G A; Druzhinin, V P; Korol, A A ...
Journal of physics. Conference series,
10/2017, Letnik:
898, Številka:
3
Journal Article
Recenzirano
Odprti dostop
The spherical neutral detector (SND) takes data at the e+e- collider VEPP-2000 in Novosibirsk. We present here recent upgrades of the SND DAQ system which are mainly aimed to handle the enhanced ...events rate load after the collider modernization. To maintain acceptable events selection quality the electronics throughput and computational power should be increased. These goals are achieved with the new fast digitizing electronics and distributed data taking. The data flow for the most congested detector subsystems is distributed and processed separately. We describe the new distributed SND DAQ software architecture, its computational and network infrastructure.
The cross section for the process
e
+
e
−
→
ηK
+
K
−
wasmeasured at c.m. energies in the range between 1.56 and 2.00 GeV in an experiment with the SND detector at the VEPP-2000
e
+
e
−
collider. The ...invariant-mass distribution of kaon pairs is consistent with the hypothesis that the transition through the
ηφ
intermediate state makes a dominant contribution to the transition in question.
The Spherical Neutral Detector (SND) is an experiment for e+e− annihilation study at low energies 0.2−2 GeV. The light quark anti−quark bound states are the main subject of study at these energies. ...They express themselves as resonances in the e+e− hadronic cross sections. Hadronic cross sections could be recalculated to hadronic vacuum polarization (HVP). The Standard Model predictions today are limited by HVP which is not calculable with modern QCD theory. In this talk we present the review of the hadronic cross sections measurements at SND and new measurements: e+e− → π+π−, π0γ, π+π−π0, ωπ0, K+K−η, η, KsKLπ0, π+π−π0η, ωπ0η e.t.c.
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