The tagging system (TS) of the KEDR detector is designed for study of two-photon interactions on the VEPP-4M electron-positron collider. The upgrade of the TS was completed and 8 triple-GEM detectors ...were added to the system with a single detector sensitive area up to 250*100 mu m super(2), a spatial resolution in the beam orbit plane close to 70 mu m and a small angle stereo readout providing a resolution of around 200 mu m in perpendicular direction. The triple-GEM detectors were included into the KEDR DAQ system, and since the beginning of the 2010-2011 season they have demonstrated stable operation at a gas gain of 20000-40000 and efficiency of 95-97%. The new detectors will allow performing background suppression and improving the energy resolution of the system.
The KEDR detector Anashin, V. V.; Aulchenko, V. M.; Baldin, E. M. ...
Physics of particles and nuclei,
07/2013, Letnik:
44, Številka:
4
Journal Article
Recenzirano
The KEDR detector is a universal magnetic detector designed for studying the
c
- and
b
-quarks and two-photon physics, and is employed at the VEPP-4M
e
+
e
−
collider. A specific feature of the ...experiment is the measurement of absolute beam energy using two methods: the resonant depolarization and the faster but less precise Compton backscattering of laser photons. This allowed a large series of measurements to be performed, in which the accuracy of determination of such fundamental parameters of particles as mass and total and leptonic widths was improved.
We report the final results of a study of the ψ(3770) meson using a data sample collected with the KEDR detector at the VEPP-4M electron–positron collider. The data analysis takes into account ...interference between the resonant and nonresonant DD¯ production, where the latter is related to the nonresonant part of the energy-dependent form factor FD. The vector dominance approach and several empirical parameterizations have been tried for the nonresonant FDNR(s).
Our results for the mass and total width of ψ(3770) areM=3779.2−1.7+1.8−0.7+0.5−0.3+0.3 MeV,Γ=24.9−4.0+4.6−0.6+0.5−0.9+0.2 MeV, where the first, second and third uncertainties are statistical, systematic and model, respectively. For the electron partial width two possible solutions have been found:(1)Γee=154−58+79−9+17−25+13 eV,(2)Γee=414−80+72−26+24−10+90 eV. Our statistics are insufficient to prefer one solution to another. The Solution (2) mitigates the problem of non-DD¯ decays but is disfavored by potential models.
It is shown that taking into account the resonance–continuum interference in the near-threshold region affects resonance parameters, thus the results presented cannot be directly compared with the corresponding PDG values obtained ignoring this effect.
A high-precision determination of the main parameters of the ψ(2S) resonance has been performed with the KEDR detector at the VEPP-4M e+e− collider in three scans of the ψ(2S)–ψ(3770) energy range. ...Fitting the energy dependence of the multihadron cross section in the vicinity of the ψ(2S) we obtained the mass valueM=3686.114±0.007±0.011−0.012+0.002 MeV and the product of the electron partial width by the branching fraction into hadronsΓee×Bh=2.233±0.015±0.037±0.020 keV. The first and second uncertainties are statistical and systematic, respectively. The third uncertainty quoted is an estimate of the model dependence of the result due to assumptions on the interference effects in the cross section of the single-photon e+e− annihilation to hadrons explicitly considered in this work. Implicitly, the same assumptions were employed to obtain the charmonium leptonic width and the absolute branching fractions in many experiments.
Using the result presented and the world average values of the electron and hadron branching fractions, one obtains the electron partial width and the total width of the ψ(2S):Γee=2.282±0.015±0.038±0.021 keV,Γ=296±2±8±3 keV.
These results are consistent with and more than two times more precise than any of the previous experiments.
Previous studies showed that large amounts of phenylcarboxylic acids (PhCAs) are accumulated in a septic patient’s blood due to increased endogenous and microbial phenylalanine and tyrosine ...biotransformation. Frequently, biochemical aromatic amino acid transformation into PhCAs is considered functionally insignificant for people without monogenetic hereditary diseases. The blood of healthy people contains the same PhCAs that are typical for septic patients as shown in this paper. The overall serum PhCAs level was 6 μM on average as measured by gas chromatography with flame ionization detection. This level is a stable biochemical parameter indicating the normal metabolism of aromatic amino acids. The concentrations of PhCAs in the metabolic profile of healthy people are distributed as follows: phenylacetic ≈
p
-hydroxyphenyllactic >
p
-hydroxyphenylacetic > phenyllactic ≈ phenylpropionic > benzoic. We conclude that maintaining of stable PhCAs level in the serum is provided as the result of integration of human endogenous metabolic pathways and microbiota.
A new high precision measurement of the J/ψ- and ψ′-meson masses has been performed at the VEPP-4M collider using the KEDR detector. The resonant depolarization method has been employed for the ...absolute calibration of the beam energy. The following mass values have been obtained: MJ/ψ=3096.917±0.010±0.007 MeV,Mψ′=3686.111±0.025±0.009 MeV. The relative measurement accuracy has reached 4×10−6 for J/ψ and 7×10−6 for ψ′, approximately 3 times better than in the previous precise experiments.
We report results of a search for narrow resonances in e+e− annihilation at center-of-mass energies between 1.85 and 3.1 GeV performed with the KEDR detector at the VEPP-4M e+e− collider. The upper ...limit on the leptonic width of a narrow resonance ΓeeR⋅Br(R→hadr)<120 eV has been obtained (at 90% C.L.).
Measurement of parameters Anashin, V V; Aulchenko, V M; Baldin, E M ...
Physics letters. B,
05/2012, Letnik:
711, Številka:
3-4
Journal Article
Recenzirano
We report the final results of a study of the psi ( 3770 ) meson using a data sample collected with the KEDR detector at the VEPP-4M electron-positron collider. The data analysis takes into account ...interference between the resonant and nonresonant D D macr production, where the latter is related to the nonresonant part of the energy-dependent form factor F D . The vector dominance approach and several empirical parameterizations have been tried for the nonresonant F D N R ( s ) . Our results for the mass and total width of psi ( 3770 ) are M = 3779.2 - 1.7 + 1.8 - 0.7 + 0.5 - 0.3 + 0.3 MeV , Gamma = 24.9 - 4.0 + 4.6 - 0.6 + 0.5 - 0.9 + 0.2 MeV , where the first, second and third uncertainties are statistical, systematic and model, respectively. For the electron partial width two possible solutions have been found: ( 1 ) Gamma e e = 154 - 58 + 79 - 9 + 17 - 25 + 13 eV , ( 2 ) Gamma e e = 414 - 80 + 72 - 26 + 24 - 10 + 90 eV . Our statistics are insufficient to prefer one solution to another. The Solution (2) mitigates the problem of non- D D macr decays but is disfavored by potential models. It is shown that taking into account the resonance-continuum interference in the near-threshold region affects resonance parameters, thus the results presented cannot be directly compared with the corresponding PDG values obtained ignoring this effect.
A high-precision determination of the main parameters of the psi ( 2 S ) resonance has been performed with the KEDR detector at the VEPP-4M e + e - collider in three scans of the psi ( 2 S ) - psi ( ...3770 ) energy range. Fitting the energy dependence of the multihadron cross section in the vicinity of the psi ( 2 S ) we obtained the mass value M = 3686.114 plus or minus 0.007 plus or minus 0.011 - 0.012 + 0.002 MeV and the product of the electron partial width by the branching fraction into hadrons Gamma e e B h = 2.233 plus or minus 0.015 plus or minus 0.037 plus or minus 0.020 keV . The first and second uncertainties are statistical and systematic, respectively. The third uncertainty quoted is an estimate of the model dependence of the result due to assumptions on the interference effects in the cross section of the single-photon e + e - annihilation to hadrons explicitly considered in this work. Implicitly, the same assumptions were employed to obtain the charmonium leptonic width and the absolute branching fractions in many experiments. Using the result presented and the world average values of the electron and hadron branching fractions, one obtains the electron partial width and the total width of the psi ( 2 S ) : Gamma e e = 2.282 plus or minus 0.015 plus or minus 0.038 plus or minus 0.021 keV , Gamma = 296 plus or minus 2 plus or minus 8 plus or minus 3 keV . These results are consistent with and more than two times more precise than any of the previous experiments.
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