The process
e
+
e
-
→
η
η
γ
is studied in the center-of-mass energy range 1.17–2.00 GeV using data with an integrated luminosity of 201 pb
-
1
collected by the SND detector at the VEPP-2000
e
+
e
-
...collider. The
e
+
e
-
→
η
η
γ
cross section is measured for the first time. It is shown that the dominant mechanism of this reaction is the transition through the
ϕ
η
intermediate state. Our result on the
e
+
e
-
→
η
η
γ
cross section is consistent with the
e
+
e
-
→
ϕ
η
measurement in the
ϕ
→
K
+
K
-
mode. The search for radiative processes contributing to the
e
+
e
-
→
η
η
γ
cross section is performed, and no significant signal is observed.
The process Formula omitted is studied in the experiment at the VEPP-2000 Formula omitted collider with the SND detector. The technique of the time measurements in the multichannel NaI(Tl) ...electromagnetic calorimeter is used to select Formula omitted events. The value of the measured cross section in the center-of-mass energy range from 1.894 to 2 GeV varies from 0.5 to 0.35 nb. The effective neutron timelike form factor is derived from the measured cross section and compared with the proton form factor. The ratio of the neutron electric and magnetic form factors is obtained from the analysis of the antineutron polar angle distribution and found to be consistent with unity.
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 process Formula omitted is studied in the center-of-mass energy range 1.17-2.00 GeV using data with an integrated luminosity of 201 pb Formula omitted collected by the SND detector at the ...VEPP-2000 Formula omitted collider. The Formula omitted cross section is measured for the first time. It is shown that the dominant mechanism of this reaction is the transition through the Formula omitted intermediate state. Our result on the Formula omitted cross section is consistent with the Formula omitted measurement in the Formula omitted mode. The search for radiative processes contributing to the Formula omitted cross section is performed, and no significant signal is observed.
The process e+e-→K+K-π0 is studied with the SND detector at the VEPP-2000 e+e- collider. Basing on data with an integrated luminosity of 26.4 pb-1 we measure the e+e-→K+K-π0 cross section in the ...center-of-mass energy range from 1.28 up to 2 GeV. The measured mass spectrum of the Kπ system indicates that the dominant mechanism of this reaction is the transition through the K∗(892)K intermediate state. The cross section for the ϕπ0 intermediate state is measured separately. The SND results are consistent with previous measurements in the BABAR experiment and have comparable accuracy. We study the effect of the interference between the ϕπ0 and K∗K amplitudes. It is found that the interference gives sizable contribution to the measured e+e-→ϕπ0→K+K-π0 cross section below 1.7 GeV.
Abstract The process $$e^+e^-\rightarrow K^+K^-\pi ^0$$ e + e - → K + K - π 0 is studied with the SND detector at the VEPP-2000 $$e^+e^-$$ e + e - collider. Basing on data with an integrated ...luminosity of 26.4 $$\hbox {pb}^{-1}$$ pb - 1 we measure the $$e^+e^-\rightarrow K^+K^-\pi ^0$$ e + e - → K + K - π 0 cross section in the center-of-mass energy range from 1.28 up to 2 GeV. The measured mass spectrum of the $$K\pi $$ K π system indicates that the dominant mechanism of this reaction is the transition through the $$K^{*}(892)K$$ K ∗ ( 892 ) K intermediate state. The cross section for the $$\phi \pi ^0$$ ϕ π 0 intermediate state is measured separately. The SND results are consistent with previous measurements in the BABAR experiment and have comparable accuracy. We study the effect of the interference between the $$\phi \pi ^0$$ ϕ π 0 and $$K^*K$$ K ∗ K amplitudes. It is found that the interference gives sizable contribution to the measured $$e^+e^- \rightarrow \phi \pi ^0\rightarrow K^+K^-\pi ^0$$ e + e - → ϕ π 0 → K + K - π 0 cross section below 1.7 GeV.
Abstract
The process
$$e^+e^-\rightarrow K^+K^-\pi ^0$$
e
+
e
-
→
K
+
K
-
π
0
is studied with the SND detector at the VEPP-2000
$$e^+e^-$$
e
+
e
-
collider. Basing on data with an integrated ...luminosity of 26.4
$$\hbox {pb}^{-1}$$
pb
-
1
we measure the
$$e^+e^-\rightarrow K^+K^-\pi ^0$$
e
+
e
-
→
K
+
K
-
π
0
cross section in the center-of-mass energy range from 1.28 up to 2 GeV. The measured mass spectrum of the
$$K\pi $$
K
π
system indicates that the dominant mechanism of this reaction is the transition through the
$$K^{*}(892)K$$
K
∗
(
892
)
K
intermediate state. The cross section for the
$$\phi \pi ^0$$
ϕ
π
0
intermediate state is measured separately. The SND results are consistent with previous measurements in the BABAR experiment and have comparable accuracy. We study the effect of the interference between the
$$\phi \pi ^0$$
ϕ
π
0
and
$$K^*K$$
K
∗
K
amplitudes. It is found that the interference gives sizable contribution to the measured
$$e^+e^- \rightarrow \phi \pi ^0\rightarrow K^+K^-\pi ^0$$
e
+
e
-
→
ϕ
π
0
→
K
+
K
-
π
0
cross section below 1.7 GeV.
Abstract
The process
$$e^+e^-\rightarrow \eta \pi ^0\gamma $$
e
+
e
-
→
η
π
0
γ
is studied in the center-of-mass energy range 1.05–2.00 GeV using data with an integrated luminosity of 94.5
$$\hbox ...{pb}^{-1}$$
pb
-
1
collected by the SND detector at the VEPP-2000
$$e^{+}e^{-}$$
e
+
e
-
collider. The
$$e^+e^-\rightarrow \eta \pi ^0\gamma $$
e
+
e
-
→
η
π
0
γ
cross section is measured for the first time. It is shown that the dominant mechanism of this reaction is the transition through the
$$\omega \eta $$
ω
η
intermediate state. The measured cross section of the subprocess
$$e^+e^-\rightarrow \omega \eta \rightarrow \eta \pi ^0\gamma $$
e
+
e
-
→
ω
η
→
η
π
0
γ
is consistent with previous measurements in the
$$e^+e^-\rightarrow \pi ^+\pi ^-\pi ^0\eta $$
e
+
e
-
→
π
+
π
-
π
0
η
mode. It is found, with a significance of
$$5.6\sigma $$
5.6
σ
, that the process
$$e^+e^-\rightarrow \eta \pi ^0\gamma $$
e
+
e
-
→
η
π
0
γ
is not completely described by hadronic vector-pseudoscalar intermediate states. The cross section of this missing contribution, which can originate from radiation processes, e. g.
$$e^+e^-\rightarrow a_{0}(1450)\gamma $$
e
+
e
-
→
a
0
(
1450
)
γ
, is measured. It is found to be 15–20 pb in the wide energy range from 1.3 to 1.9 GeV.
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