The cross section of the process e + e − → π + π − has been measured in the center-of-mass energy range from 0.32 to 1.2 GeV with the CMD-3 detector at the electron-positron collider VEPP-2000. The ...measurement is based on an integrated luminosity of about 88 pb − 1 , of which 62 pb − 1 represent a complete dataset collected by CMD-3 at center-of-mass energies below 1 GeV. In the dominant region near the ρ resonance a systematic uncertainty of 0.7% was achieved. The implications of the presented results for the evaluation of the hadronic contribution to the anomalous magnetic moment of the muon are discussed. Published by the American Physical Society 2024
The article develops the possibility of forming silicon oxide structures with tapered walls using dry etching methods, including a two-stage process involving the formation of a tapered photoresist ...mask and plasma etching of the silicon oxide. A study of the process of tapered resist etching was carried out. The influence of plasma parameters and composition on the etching process was studied, plasma diagnostics were carried out using Langmuir probe and optical emission actinometry methods, and the mechanisms of tapered resist etching were suggested. The etching process was optimized and structures with a resist thickness of 400 nm and a sidewall angle of up to 61° were obtained. A subsequent SiO
2
etching process allowed the slope of the resist to be transferred. The slope of the SiO
2
wall was 57°. The resulting structures with tapered SiO
2
walls make it possible to produce capacitors for studying the characteristics of dielectrics, as well as the structure of microelectromechanics and microfluidics.
The process e+e−→K+K− has been studied using 1.7×106 events from a data sample corresponding to an integrated luminosity of 5.7 pb−1 collected with the CMD-3 detector in the center-of-mass energy ...range 1010–1060 MeV. The cross section is measured with about 2% systematic uncertainty and is used to calculate the contribution to the anomalous magnetic moment of the muon aμK+K−=(19.33±0.40)×10−10, and to obtain the ϕ(1020) meson parameters. We consider the relationship between the e+e−→K+K− and e+e−→KS0KL0 cross sections and compare it to the theoretical prediction.
The process e+e−→K+K−η has been studied in the center-of-mass energy range from 1.59 to 2.007 GeV using the data sample of 59.5 pb−1, collected with the CMD-3 detector at the VEPP-2000 e+e− collider ...in 2011, 2012 and 2017. The K+K−η final state is found to be dominated by the contribution of the ϕ(1020)η intermediate state. The cross section of the process e+e−→ϕ(1020)η has been measured with a systematic uncertainty of 5.1% on the base of 3009 ± 67 selected events. The obtained cross section has been used to calculate the contribution to the anomalous magnetic moment of the muon: aμϕη(E<1.8GeV)=(0.321±0.015stat±0.016syst)×10−10, aμϕη(E<2.0GeV)=(0.440±0.015stat±0.022syst)×10−10. From the cross section approximation the ϕ(1680) meson parameters have been determined with better statistical precision, than in previous studies.
The cross section of the process e + e − → π + π − has been measured in the center of mass energy range from 0.32 to 1.2 GeV with the CMD-3 detector at the electron-positron collider VEPP-2000. The ...measurement is based on a full dataset collected below 1 GeV during three data taking seasons, corresponding to an integrated luminosity of about 62 pb − 1 . In the dominant ρ -resonance region, a systematic uncertainty of 0.7% has been reached. At energies around ϕ -resonance the π + π − production cross section was measured for the first time with high beam energy resolution. The forward-backward charge asymmetry in the π + π − production has also been measured. It shows a strong deviation from the theoretical prediction based on the conventional scalar quantum electrodynamics framework, and it is in good agreement with the generalized vector-meson-dominance and dispersive-based predictions. The impact of the presented results on the evaluation of the hadronic contribution to the anomalous magnetic moment of muon is discussed. Published by the American Physical Society 2024
The process e+e−→K+K−π+π− has been studied in the center-of-mass energy range from 1500 to 2000 MeV using a data sample of 23 pb−1 collected with the CMD-3 detector at the VEPP-2000 e+e− collider. ...Using about 24 000 selected events, the e+e−→K+K−π+π− cross section has been measured with a systematic uncertainty decreasing from 11.7% at 1500–1600 MeV to 6.1% above 1800 MeV. A preliminary study of K+K−π+π− production dynamics has been performed.
Overview of the CMD-3 recent results Ryzhenenkov, A E; Akhmetshin, R R; Amirkhanov, A N ...
Journal of physics. Conference series,
04/2020, Volume:
1526, Issue:
1
Journal Article
Peer reviewed
Open access
The CMD-3 detector started data taking at the electron-positron collider VEPP-2000 in December 2010 with a goal to collect about 1 fb−1. The collected data sample corresponds to an integrated ...luminosity of 200 pb−1 in the center-of-mass energy range from 0.32 up to 2 GeV. This paper reports recent results on the hadronic cross sections measurements with the CMD-3 detector.
We study the influence of the chemical composition and the conditions of thermomechanical and thermal treatments on the structural strength determined by the characteristics of strength and cyclic ...crack-growth resistance, as well as on the corrosion and corrosion-fatigue properties of alloys of the Ti–Nb–Si and Ti–Nb–Zr–Si systems. These characteristics are compared with the characteristics determined for the extensively used Ti–Al–V alloy intended for biomedical applications. It is shown that, under the conditions of reliable control over the formation and development of mechanical defects (fatigue cracks) in the products made of Ti–18.7Nb–1.0Si alloy, this alloy may serve as a good alternative to Ti–6Al–4V alloy.
The features and changes in the microstructure of the electrode material of the negative electrode of the lead–acid starter accumulator battery appearing on the addition of two different specimens of ...carbon carbon black and hybrid carbon, are investigated. The X-ray phase analysis and the scanning electron microscopy analysis are conducted. It is established that using carbon black or hybrid carbon as an additive to the material of the negative electrode influences its structure causing changes in the processes of its impregnation and formation. Based on the structural analysis, a qualitative description, according to which hybrid carbon increases the dispersity of the negative active mass and impedes the diffusion of sulfate-ions, is proposed. The standard tests were conducted by intensive cycling in the partial state of charge lead–acid starter batteries in the charge–discharge mode. The batteries were manufactured using negative plates with additives of technical or hybrid carbon. The influence of each type of carbon additive on the electrical characteristics of the starter batteries is determined. It is shown that the additive of hybrid carbon increases the service life of starter batteries under operation in the partial state of the charge. This additive increases the charge acceptance on average by 9% and the deep discharge stability of the battery. The capacity loss after deep discharge is less than 4.4% if hybrid carbon is used as an additive and 7.2% in the case of carbon black.
The cross section of the process
e
+
e
−
→ π
+
π
−
π
+
π
−
has been measured using an integrated luminosity of 17 pb
−1
collected with the CMD-3 detector in the center-of-mass energy range 650-1000 ...MeV. High-precision measurements of various hadronic cross sections are of great interest in relation with the problem of the muon anomalous magnetic moment g-2. This measurement can be also used to test the relation between the cross section of
e
+
e
−
→ π
+
π
−
π
+
π
−
and the spectral function for the τ
−
→ π
−
π
0
π
0
π
0
decay predicted by the conservation of vector current (CVC).