Detector electronics for experiments at the large hadron collider

The state of the art of a tracking detector and calorimeter electronics that are being developed for experiments at the Large Hadron Collider (LHC) is discussed. Construction of the detectors is briefly described. The problems of fabrication of integrated circuits based on a radiation-resistant technology are considered, as well as the solution to the problem of microconnections between sensitive elements and readout amplifiers in two-coordinate semiconductor detectors. The parameters and block diagrams of both analog and digital integrated circuits are given; these circuits are used for amplifying and shaping the signals measured by tracking detectors of elementary particles and calorimeters. The contributions of Russian experimenters and physicists of the Joint Institute for Nuclear Research to the development of detector electronics for experiments at the LHC is described.     

On symbolic-numerical representation of the evolution operator for finite-dimensional quantum systems

A symbolic algorithm to generate the multilayer operator-difference schemes for solving the evolution problem of the time-dependent Schrödinger equation is elaborated. An additional gauge transformation of operator-difference schemes to make good use of the finite-element discretization is applied. The efficiency of the generated numerical schemes until the sixth order with respect to the time step and until the seventh order with respect to the spatial step is demonstrated by calculations of some finite-dimensional quantum systems in external fields.     

Experiments on the gravity effect on the109Ag gamma resonance

The temperature dependence of the ¹⁰⁹Ag γ-ray self-absorption was investigated for the horizontal and vertical directions of emission. The source was a single-crystal silver plate containing atoms of parent radionuclide ¹⁰⁹Cd. Gamma-radiation of this γ-source and that of the monitoring γ-source, ⁵⁷Co, were registered by a pair of Ge(Li)-detectors. As a result of cooling the source from 77 K to ~12 K a relative decrease was observed of the intensity of the horizontally emitted γ-rays equal to 0.00064±0.00044. For the vertical direction the corresponding intensity change turned out to be -0.00047±0.00051. Although these data, as one would see, give some evidence for the possible effect of the gravitation on the resonant γ-ray absorption, future measurements must show if these results aren’t a consequence of any apparatus effect. The ways for developments in this study are discussed and some hindrances are considered. This revised version was published online in August 2006 with corrections to the Cover Date.     

Light quark fragmentations into pions

We discuss a process of hadronization of light quarks into charged pions in e ⁺ e ⁻ annihilations and in deep inelastic scatering of charged leptons and neutrino off nucleons. The corresponding semi-inclusive cross-sections of pions production we write in terms of quark fragmentation functions and fracture functions. We suggest a new method of measurements of fragmentation and fracture functions based on analysis of semiinclusive data.     

Charm dimuon production in neutrino-nucleon interactions in the NOMAD experiment

We present our new measurement of charm dimuon production in neutrino-iron interactions based upon the full statistics collected by the NOMAD experiment. After background subtraction we observe 15,340 charm dimuon events, providing the largest sample currently available. The analysis exploits the large inclusive charged current sample (about 9 million events after all analysis cuts) to constrain the total systematic uncertainty to ∼2%. The extraction of strange sea and charm production parameters is also discussed.     

Experimental evidence of time-delay-induced death in coupled limit-cycle oscillators

Experimental observations of time-delay-induced amplitude death in two coupled nonlinear electronic circuits that are individually capable of exhibiting limit-cycle oscillations are described. The existence of multiply connected death islands in the parameter space of coupling strength and time delay for coupled identical oscillators is established. The existence of such regions was predicted earlier on theoretical grounds [Phys. Rev. Lett. 80, 5109 (1998); Physica (Amsterdam) 129D, 15 (1999)]. The experiments also reveal the occurrence of multiple frequency states, frequency suppression of oscillations with increased time delay, and the onset of both in-phase and antiphase collective oscillations.     

Experiment for search for sterile neutrino at SM-3 reactor

In connection with the question of possible existence of sterile neutrino the laboratory on the basis of SM-3 reactor was created to search for oscillations of reactor antineutrino. A prototype of a neutrino detector with scintillator volume of 400 l can be moved at the distance of 6–11 m from the reactor core. The measurements of background conditions have been made. It is shown that the main experimental problem is associated with cosmic radiation background. Test measurements of dependence of a reactor antineutrino flux on the distance from a reactor core have been made. The prospects of search for oscillations of reactor antineutrino at short distances are discussed.     

Detection of <Emphasis Type="Italic">trans</Emphasis>-isomers of hydrocarbon residues of lipid molecules by IR absorption

IR spectroscopy is used for a comparative analysis of the trans-isomerization of double bonds in hydrocarbon residuals of lactic and hydrogenated lipids. The maximum of the absorption band of the trans-isomers for all the lipid samples is found to lie at 965 cm⁻¹. An absorption band at 970 cm⁻¹ is discovered in the spectra of the lactic lipids near the analytic band of the trans-isomers at 965 cm⁻¹. Based on a gaussian approximation for their absorption spectral bands, the trans-isomer content in the lactic lipid samples is 10–11%. The absorption by lipid molecules at 970 cm⁻¹ has to be taken into account when determining the trans-isomer content of fat and oil products. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 76, No. 1, pp. 138–142, January–February, 2009.