First samples of Ti and Nb tubes explosion welding joint with stainless steel for ILC 1.8 K cryomodule

The world first samples of Ti and Nb tubes joint with stainless steel ones by an explosion welding by the JINR-VNIIEF-FNAL-INFN cooperation were manufactured in the frame of ILC R&D programe. An applying methods of relaxation of residual tensions (after explosion and electron beam welding), macro- and microanalyses of welding seam and cryogenic tests of the samples produced manifest the achievement of high mechanic strength (≈250 MPa/share) of welding seam, solidity and leak absence on 10^?10 l atm/s level at 1.8 K. The explosion welding technology and methods introducing to industrial manufacturing of the 4-th generation of cryomodule of TESLA TYPE DESIGN can exclude the Ti—communications, connect the Nb—cavity with stainless steel vessel and reduce significantly the accelerator cost.     

Analytic perturbation theory in analyzing some QCD observables

This paper is devoted to the application of the recently devised ghost-free analytic perturbation theory (APT) for the analysis of some QCD observables. We start with a discussion of the main problem of the perturbative QCD, ghost singularities, and with a resume of its resolving within the APT. By a few examples in various energy and momentum transfer regions (with the flavor number f=3,4 and 5) we demonstrate the effect of the improved convergence of the APT modified perturbative QCD expansion. Our first observation is that in the APT analysis the three-loop contribution () is as a rule numerically inessential. This gives hope for a practical solution of the well-known problem of the asymptotic nature of the common QFT perturbation series. The second result is that the usual perturbative analysis of time-like events with the large term in the coefficient is not adequate at . In particular, this relates to decay. Then for the “high” () region it is shown that the common two-loop (NLO, NLLA) perturbation approximation widely used there (at ) for the analysis of shape/events data contains a systematic negative error at the 1–2 per cent level for the extracted values. Our physical conclusion is that the value averaged over the data appreciably differs, , from the currently accepted “world average” (=0.118). Received: 30 July 2001 / Published online: 5 November 2001     

Acceleration complex for extreme ultraviolet nanolithography based on a free-electron laser with kilowatt-scale average radiation power

The project of an acceleration complex is described that is based on a 0.7-GeV superconducting linear accelerator for the free-electron laser used for extreme ultraviolet lithography at a 13.5-nm wavelength with a 0.5-kW average power of laser radiation, as well as for examination of materials using X-ray and vacuum-ultraviolet radiations.     

“Massive” perturbative QCD, Regular in the IR limit

The goal of the research is to devise a modification of the perturbative QCD (pQCD) that should be regular in the low-energy region and could serve as a practical means for the analysis of data below 1 GeV down to the IR limit. Recent observation of the four-loop pQCD series “blow-up” in the region below 1 GeV for the Bjorken Sum Rule gave an impetus to this attempt. The proposed “massive” analytic pQCD has two sources. It can be treated as the common logarithmic pQCD with only one parameter added, the effective “glueball mass” m _gl ? 1 GeV, serving as an IR regulator. At the same time, it looks like a modification of Analytic Perturbation Theory (APT) comprising nonpower perturbative expansion that makes it compatible with linear integral transformations. Figuratively (with minor reservations), the proposed MAPT differs from the minimal APT by simple ansatz Q ² → Q ² + m _g1 ² .     

Rovibrational interactions in linear triatomic molecules: a theoretical study in curvilinear vibrational coordinates

Variational solution of the rovibrational problem in curvilinear vibrational coordinates has been implemented and used to investigate the nuclear motions in several linear triatomic molecules, like HCN, OCS, and HCP. The dependence of the rovibrational energy levels on the rotational quantum numbers and the l-doubling has been studied. Two approximations to the rovibrational Hamiltonian have been examined, depending on the level of truncation of the potential energy operator. It turns out that the truncation after the fifth order in the potential is sufficient to produce vibrational energies of high accuracy. An interesting feature of the present formulation of the problem in terms of the curvilinear vibrational coordinates is the explanation of the l-doubling of the rovibrational levels, which in this picture is interpreted as the result of the inequivalency of the average rotational constants in mutually perpendicular planes, rather than as the effect of the Coriolis-type interactions between the vibrational and rotational motions. The present theoretical results are compared with the available experimental data from high-resolution spectroscopy, as well as with other ab initio calculations.     

Superconducting synchrotron project for hadron therapy

The project of a superconducting medical synchrotron for carbon therapy in the ion energy range from 140 to 400 MeV/n is discussed in this paper. This project is aimed at developing and building a medical synchrotron on the basis of superconducting technologies at JINR under the construction of the Nuclotron accelerator complex. A linear accelerator with alternating phase focusing is proposed for injecting carbon ion into the synchrotron, while it is planned to use a superconducting gantry weighing about 150 t for delivering radiation treatment to patients from all directions.     

Renormalization group, causality, and nonpower perturbation expansion in QFT

The structure of the QFT expansion is studied in the framework of a new “invariant analytic” version of the perturbative QCD. Here, an invariant coupling constant α(Q ² /Λ ² ) = β ₁ α_s(Q ² )/(4π) becomes a Q ² -analytic invariant function α _an (Q²/Λ ² ) ≡A(x), which, by construction, is free of ghost singularities because it incorporates some nonperturbative structures. In the framework of the “analyticized” perturbation theory, an expansion for an observable F, instead of powers of the analytic invariant charge A(x), may contain specific functions A_n(x)=[aⁿ(x)] _an , the “nth power of a(x) analyticized as a whole.” Functions A _n>2(x) for small Q² ≤Λ ² oscillate, which results in weak loop and scheme dependences. Because of the analyticity requirement, the perturbation series for F(x) becomes an asymptotic expansion à la Erdélyi using a nonpower set {A _n (x)}. The probable ambiguities of the invariant analyticization procedure and the possible inconsistency of some of its versions with the renormalization group structure are also discussed. Translated from Teoreticheskaya i Matematicheskaya Fizika, Vol. 119, No. 1, pp. 55–66, April, 1999.     

Comparative analysis of earthquakes data recorded by the innovative Precision Laser Inclinometer instruments and the classic Hydrostatic Level System

The Hydrostatic Level System (HLS) data and the Precision Laser Inclinometer (PLI) instruments data have been comparatively analyzed in the event of surface angular oscillations induced by earthquakes. The comparative data analysis has shown an agreement on the arrival and stop time of earthquakes. The data have been analyzed within the instruments sensitivity ranges having an overlap in frequency intervals.     

Ultraviolet behaviour of spontaneously broken gauge theories

The asymptotic invariant coupling constant (ICC) in the repulsive σ⁴ interaction is shown to be finite in the second logarithmic approximation. It leads to spontaneously broken gauge theories free of ultraviolet (UV) troubles.