104 research outputs found
New precise determination of the \tau lepton mass at KEDR detector
The status of the experiment on the precise lepton mass measurement
running at the VEPP-4M collider with the KEDR detector is reported. The mass
value is evaluated from the cross section behaviour around the
production threshold. The preliminary result based on 6.7 pb of data is
MeV. Using 0.8 pb of data
collected at the peak the preliminary result is also obtained:
eV.Comment: 6 pages, 8 figures; The 9th International Workshop on Tau-Lepton
Physics, Tau0
Measurement of \Gamma_{ee}(J/\psi)*Br(J/\psi->e^+e^-) and \Gamma_{ee}(J/\psi)*Br(J/\psi->\mu^+\mu^-)
The products of the electron width of the J/\psi meson and the branching
fraction of its decays to the lepton pairs were measured using data from the
KEDR experiment at the VEPP-4M electron-positron collider. The results are
\Gamma_{ee}(J/\psi)*Br(J/\psi->e^+e^-)=(0.3323\pm0.0064\pm0.0048) keV,
\Gamma_{ee}(J/\psi)*Br(J/\psi->\mu^+\mu^-)=(0.3318\pm0.0052\pm0.0063) keV.
Their combinations
\Gamma_{ee}\times(\Gamma_{ee}+\Gamma_{\mu\mu})/\Gamma=(0.6641\pm0.0082\pm0.0100)
keV,
\Gamma_{ee}/\Gamma_{\mu\mu}=1.002\pm0.021\pm0.013 can be used to improve
theaccuracy of the leptonic and full widths and test leptonic universality.
Assuming e\mu universality and using the world average value of the lepton
branching fraction, we also determine the leptonic \Gamma_{ll}=5.59\pm0.12 keV
and total \Gamma=94.1\pm2.7 keV widths of the J/\psi meson.Comment: 7 pages, 6 figure
Search for narrow resonances in e+ e- annihilation between 1.85 and 3.1 GeV with the KEDR Detector
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 Gamma(R -> ee) Br(R -> hadr) < 120 eV has been obtained
(at 90 % C.L.)
Measurement of and between 3.12 and 3.72 GeV at the KEDR detector
Using the KEDR detector at the VEPP-4M collider, we have measured
the values of and at seven points of the center-of-mass
energy between 3.12 and 3.72 GeV. The total achieved accuracy is about or
better than at most of energy points with a systematic uncertainty of
about . At the moment it is the most accurate measurement of in
this energy range
Measurement of main parameters of the \psi(2S) resonance
A high-precision determination of the main parameters of the \psi(2S)
resonance has been performed with the KEDR detector at the VEPP-4M e^{+}e^{-}
collider in three scans of the \psi(2S) -- \psi(3770) energy range. Fitting the
energy dependence of the multihadron cross section in the vicinity of the
\psi(2S) we obtained the mass value
M = 3686.114 +- 0.007 +- 0.011 ^{+0.002}_{-0.012} MeV and the product of the
electron partial width by the branching fraction into hadrons \Gamma_{ee}*B_{h}
= 2.233 +- 0.015 +- 0.037 +- 0.020 keV.
The third error 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(2S):
\Gamma_{ee} =2.282 +- 0.015 +- 0.038 +- 0.021 keV,
\Gamma = 296 +- 2 +- 8 +- 3 keV.
These results are consistent with and more than two times more precise than
any of the previous experiments
Study of KS KL Coupled Decays and KL -Be Interactions with the CMD-2 Detector at VEPP-2M Collider
The integrated luminosity about 4000 inverse nanobarn of around phi meson
mass ( 5 millions of phi mesons) has been collected with the CMD-2 detector at
the VEPP-2M collider. A latest analysis of the KS KL coupled decays based on 30
% of available data is presented in this paper.
The KS KL pairs from phi meson decays were reconstructed in the drift chamber
when both kaons decayed into two charged particles. From a sample of 1423
coupled decays a selection of candidates to the CP violating KL into pi+ pi-
decay was performed. CP violating decays were not identified because of the
domination of events with a KL regenerating at the Be beam pipe into KS and a
background from KL semileptonic decays.
The regeneration cross section of 110 MeV/c KL mesons was found to be 53 +-
17 mb in agreement with theoretical expectations. The angular distribution of
KS mesons after regeneration and the total cross section of KL for Be have been
measured.Comment: 14 pages, 8 figure
Industrial electron accelerators type ILU
The paper describes ILU type industrial electron accelerators. Their main parameters, design, principle of action,
electron beam extraction devices, wide set of auxiliary equipment for various technological processes and ways of
their usage are discussed as well.Описаны промышленные ускорители электронов серии ИЛУ. Приведены основные параметры,
устройство и принцип действия. Дается краткое описание систем выпуска ускоренного пучка в атмосферу
для различных технологических процессов.Описано промислові прискорювачі електронів серії ЫЛП. Наведено основні параметри, будова і
принцип дії. Дається короткий опис систем випуску прискореного пучку в атмосферу для різних
технологічних процесів
Work status of 5 MeV 300 kW electron accelerator
Design work has been completed for the accelerating structure of high-power electron accelerator with 5 MeV,
300 kW, 176 MHz parameters. The structure is being produced in BINP workshop. The paper presents the design of
the accelerating structure which consists of a chain of coaxial cavities, and block diagram of experimental
workbench. Structure of the main accelerator blocks and their degree of fabrication are viewed.Закончены проектные работы по ускоряющей структуре мощного электронного ускорителя 5 МэВ,
300 кВт, 176 МГц и ведется ее изготовление в опытном производстве Института. Дается описание
конструкции ускоряющей структуры, состоящей из цепочки связанных коаксиальных резонаторов.
Приводится блок-схема испытательного стенда, рассматривается устройство отдельных узлов ускорителя и
состояние их готовности.Закінчено проектні роботи із прискорювальної структури потужного електронного прискорювача 5 МеВ,
300 кВт, 176 МГц і ведеться її виготовлення в дослідному виробництві інституту. Дається опис конструкції
прискорювальної структури, що складається з ланцюжка зв'язаних коаксіальних резонаторів. Приводиться
блок-схема іспитового стенда, розглядається будова окремих вузлів прискорювача і стан їх готовності
Search for rare Phi decays in pi+ pi_ gamma final state
A search for phi radiative decays has been performed using a data sample of
about 2.0 million phi decays collected by the CMD-2 detector at VEPP-2M
collider in Novosibirsk. From the selected e+ e- -> pi+ pi- gamma events the
following results were obtained: B(phi -> f0(980) gamma) < 1x10-4 for
destructive and B(phi -> f0(980) gamma) < 7x10-4 for constructive interference
with the Bremsstrahlung process respectively, B(phi -> gamma -> pi+ pi- gamma)
20 MeV, B(phi -> rho gamma) < 7x10-4. From the
selected e+ e- -> mu+ mu- gamma events B(phi -> mu+ mu- gamma) =
(2.3+-1.0)x10-5 has been obtained for E of gamma> 20 MeV. The upper limit on
the P,CP-violating decay eta -> pi+ pi- has also been placed: B(eta -> pi+ pi-)
< 9x10-4 . All upper limits are at 90 % C.L.Comment: 18 pages, 7 figure
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