Yu.A. Budagov

Measurements of the K+→π0e+ν form factors

Abstract The q2 dependence of the vector form factor has been investigated using 3.2 × 104 K+ → π0e+ν decays. The usual linear parametrization. ƒ + (q 2 ) = ƒ(0)(1+λ + q 2 /m π 0 0 ) gives λ+ = 0.0284±0.0027. An analysis of the Dalitz plot density distribution for Ke3+ decays yields the values for the scalar and tensor couplings ƒs and ƒt, and their relative phase angle ost.

Measurement of J / psi, psi-prime and upsilon total cross-sections in 800-GeV/c p - Si interactions

Abstract We report on the analysis of Charmonium and Bottomium states produced in p-Si interactions at s =38.7 GeV . The data have been collected with the open geometry spectrometer of the E771 Experiment at the FNAL High Intensity Lab. J ψ , ψ′ and γ total cross sections as well as the ratio B(ψ′ → μμ)σ(ψ′) (B( J ψ → μμ)σ( J ψ )) have been measured. Results are compared with theoretical predictions and with results at other energies.

Multi-hit drift time digitizer with one-nanosecond resolution

Abstract A multi-hit drift time digitizer is described (in the 16 μs range). It measures the time position of signals with an accuracy of 1 ns from a wide-gap drift chamber. A fast MECL memory (256 × 7 bits) in each information channel allows one to register up to 256 signals with a ⩾ 64 ns interval between pulses.

Measurement of the Dalitz plot slope parameters for K+→ π+π0π0 decay

We have measured the Dalitz plot slope parameters for the K+ → π+π0π0 decay with an accuracy higher than in previous experiments. The values obtained are substantially different from the world averages. The experiment was performed at the Serpukhov PS with the HYPERON-2 spectrometer at the beam energy 10 GeV We have collected about 33000 events with energies and momenta measured for all involved particles.

A time projection chamber for double-beta-decay experiments

Abstract A large-volume time projection chamber (TPC) designed for double-beta-decay experiments with solid samples of 2.5 m 2 total surface is described. The TPC will operate in a weak magnetic field of ≲ 0.05 T with He+20% CH 4 gas filling at atmospheric pressure. A prototype TPC operating in the 10 GeV proton beam of the IHEP Serpukhov accelerator had shown ≈100% efficiency and a spatial resolution of ≲ 0.45 mm in the direction of the drift of electrons and ≈ 1.6 mm along the delay lines. A limit on half-life of ∼ 10 24 years should be reached with the large TPC operating in the deep underground laboratory.

On the 1350 MeV Λγ peak produced in π− p interaction

Abstract The existence of the Λγ peak between 1300 and 1400 MeV was supported by our measurements. The explanation of this peak by means of the hypothetical Λη (1680 MeV) resonance can be rejected with a 97% confidence level.

Observation of specific features of laser beam propagation in air with standing acoustic waves

The process of laser beam propagation in air with a standing acoustic wave is studied. The uncertainty σ in the spatial localization of the laser beam is found to decrease in this process. In the studied case of laser beam propagation in a tube at atmospheric air pressure, the observed effect is manifested as a decrease in σ alongside the increasing resonator (tube) quality factor.

Elastic scattering of negative pions by protons at 128 and 162 MeV

The elastic scattering distribution of negative pions by protons has been measured with a hydrogen-filled diffusion cloud chamber in a magnetic field. In a set of exposures 344 and 941 elastic scattering events were recorded at anglesθ(c.m.s.) > 10°. The total cross-sections for elastic scattering σe1 (128MeV) = (12.8 ± 1.0) 10−27 cm2 and σe1(162 MeV) = (21.4 ± 1.2) 10−27 cm2 were determined by calculating the total length of negative pion tracks in the chamber. The elastic π−-p-scattering angular distributions wwere obtained in the form (the SP-analysis): dσ/dΩ(128 MeV) = (1.00±0.08)[(0.55±0.07)+(0.34±0.12) cosθ+(1.30±0.24) cos2θ] 10−27 cm2/sr, dσ/dΩ(162 MeV) = (1.00±0.06)[(0.93±0.07)+(0.51±0.12) cosθ+(2.28±0.22) cos2θ]10−27 cm2/sr. The differential forward scattering cross-sections are equal to (2.20±0.32) 10−27 cm2/sr and (3.73±0.32) 10−27 cm2/sr respectively. The real parts of the forward scattering amplitude (in c.m.s.) have been calculated in units of ℏ/mπc: D_b(128 MeV) = 0.261±0.031 and D_b(162 MeV) = 0.216±0.038. These quantities agree with those calculated from dispersion relations with the coupling constant f2 = 0.08.

Computation of single-cell superconducting niobium cavity for accelerator of electrons and positrons

Computations of the accelerator section of the International Linear Collider (ILC), which consists of superconducting niobium cavities, are performed for conditions of the maximum energy transfer to electrons that travel along the cavity axis. A mathematical model and software packages are created for the computation of the electric characteristics and profile of a single-cell cavity. A computer-based synthesis of the cavity shape that yields the required electric characteristics is performed. The promising design variants of a single-cell cavity, with which a quality factor of 1010 is provided at a working frequency of 1.3 GHz, are found to optimize the construction and manufacture of a single-cell cavity. The electric characteristics of a chain of single-cell cavities are computed.

ATLAS hadron tile calorimeter: Experience in prototype construction and module mass production

This work reflects the long-term (1994–2002) experience of JINR in organizing and participating in large-scale international cooperation of research centers and industrial enterprises of Russia, Europe, and the United States in construction of the ATLAS hadron barrel calorimeter. Considerable attention is given to RD the role of the laser metrology developed at JINR in providing high-precision assembly of main calorimeter structural components (submodules and modules) is especially emphasized.