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 CBM detector will research compressed baryon matter on the FAIR facility, GSI, Darmstadt. The superconducting dipole magnet of this detector provides vertical magnetic field with field integral ∼ ...1 T*m along a beam length of 1 m. The warm bore distance between the dipole coils is 1.44 m. Maximal magnetic field on the superconducting winding is 3.6 T. The stored energy of the magnet is ∼ 5 MJ. The superconducting coils having 1.34 m of inner diameter will be made of NbTi wire having Cu/SC ratio of 7/1. The SC wire cross-section bare size is 2.02 mm × 3.25 mm. This wire of 30 km of total length in 6 pieces was manufactured by extrusion monolith technique. The iron yoke having 139 t weight is a part of the CBM magnet. It was manufactured and assembled. The SC coils were designed according the indirect cooling principle. The superconducting winding is embedded in copper case and will be cooled by 4.5 K helium going through the copper tube attached to the copper case. Two dummy coils were manufactured and tested to choose the epoxy impregnation procedure. The cooling helium will circulate between the cryostat containing 150 l of LHe and two coils in thermosyphone regime in single loop. The vapor quality at the outlet of the thermosyphone loop is ∼ 10%. The each coil is affected by 3 MN axial force towards the nearest iron yoke. The single cylinder GFRP support strut was designed to withstand this force to have the safety factor > 4 with respect to the ultimate strength and buckling. The GFRP material was chosen and tested.
A pedestrian navigation system consisting of two foot-mounted strapdown inertial navigation systems (SINS)s is considered. The zero velocity conditions of the foot in the stance phase of a step and a ...limited distance between the feet are used for SINS corrections. The aim of the work is to study some consistency properties of the extended Kalman filter. It is shown that this consistency depends on a form of the error equations.
The paper describes a method of the charged particle identification, developed for the CMD-3 detector, installed at the VEPP-2000 e+e− collider. The method is based on application of boosted decision ...trees classifiers, trained for the optimal separation of electrons, muons, pions and kaons in the momentum range from 100 to 1200MeV/c. The input variables for the classifiers are linear combinations of the energy depositions of charged particles in 12 layers of the liquid xenon calorimeter of the CMD-3. The event samples for training of the classifiers are taken from the simulation. Various issues of the calorimeter strip channels response simulation and their calibration are considered. Application of the method is illustrated by the examples of separation of the e+e−(γ) and π+π−(γ) final states and of selection of the K+K− final state at high energies.
A
bstract
The cross section of the process
e
+
e
−
→ ηπ
+
π
−
is measured using the data collected with the CMD-3 detector at the VEPP-2000 collider in the center-of-mass energy range from 1
.
1 to 2
....
0 GeV. The decay mode
η → γγ
is used for
η
meson reconstruction in the data sample corresponding to an integrated luminosity of 78
.
3 pb
−
1
. The energy dependence of the
e
+
e
−
→ ηπ
+
π
−
cross section is fitted within the framework of vector meson dominance in order to extract the Γ(
ρ
(1450)
→ e
+
e
−
)
B
(
ρ
(1450)
→ ηπ
+
π
−
) and the Γ(
ρ
(1700)
→ e
+
e
−
)
B
(
ρ
(1700)
→ ηπ
+
π
−
) products. Based on conservation of vector current, the analyzed data are used to test the relationship between the
e
+
e
−
→ ηπ
+
π
−
cross section and the spectral function in
τ
−
→ ηπ
−
π
0
ντ
decay. The
e
+
e
−
→ ηπ
+
π
−
cross section obtained with the CMD-3 detector is in good agreement with the previous measurements.
A comparison is made of conventional pin photodetectors and modern uni-traveling-carrier photodetectors based on InGaAs/InP heterostructures. The differences in the designs of heterostructures of ...these photodetectors are considered and the resulting features of their functioning are analyzed. It is shown that with comparable photosensitivity, the saturation photocurrent of uni-traveling-carrier photodetectors is approximately four times greater than that in conventional pin photodetectors. Devices with a photosensitive area 40 μm in diameter reach the saturation current at an input optical power of 10–12 and 60–70 mW for pin and uni-traveling-carrier photodetectors, respectively (reverse bias voltage of 5 V).
Abstract
A method and a measuring device designed to determine the thermal conductivity of existing and newly created composite materials used in superconducting magnets and other objects of ...cryogenic technology are considered. The results of studies of the temperature dependence of the modern advanced materials thermal conductivity in the range from 7 to 80 K are shown.
One of the factors capable of resulting in deconfinement of fuel element cladding upon long term storage of spent nuclear fuel (SNF) is reorientation of hydrides. This work estimates the extent of ...reorientation of hydrates in unirradiated gas filled specimens of fuel element claddings of VVER-1000 reactor (Zr‒1% Nb) under the conditions simulating conditions of dry storage. The specimens with the hydrogen content of 100 and 200 ppm were exposed to thermomechanical tests according to various scenarios at hoop stresses in cladding up to 100 MPa. It has been established that the extent of reorientation of hydrides and related decrease in plasticity of cladding material are insignificant. The most significant factor influencing the extent of reorientation is the level of hoop stresses.
The main devices for generating synchrotron radiation at the SKIF synchrotron light facility under construction will be superconducting wigglers and undulators created at the Budker Institute of ...Nuclear Physics, Siberian Branch, Russian Academy of Sciences. This report presents the rationale for the choice of operating parameters, the main characteristics and design features of these devices, and their current development status.
The results of testing and performance characteristics of an indirectly cryocooled superconducting solenoid to be used at the tehrahertz (THz) spectroscopy experimental station of the free-electron ...laser at the Institute of Nuclear Physics are presented. The superconducting solenoid with a winding diameter of 102 mm and a length of 0.5 m is designed for a magnetic field of 6.5 T. A warm diameter of 80 mm is available for THz spectroscopy experiments. A superconducting wire Cu/NbTi = 1.4 is used. The design implements passive protection methods due to sectioning and secondary connected circuits in case of a sudden quench. The required field uniformity of 0.5% is ensured by using an iron yoke and additional side windings. The cryogenics of the solenoid is based on two Sumitomo HI cryocoolers. The solenoid and iron yoke are cooled by the second stage of the cryocooler via copper plates. The manufacturing technology of the solenoid is described in detail. The solenoid is tested in a liquid-helium bath and in its own cryostat. Its characteristics meet the requirements of the experimental station. The obtained field of 7.3 T is greater than the designed one due to overcooling up to 3.6 K. The magnetic field is measured both in a bath cryostat and in the designed cryostat; the results corresponded to the design calculations. The solenoid cooling time is 13 days. The quench happened only twice, at 5.6 and 7.3 T.
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