научный журнал по физике Ядерная физика ISSN: 0044-0027

LAWSON T. — 2004 г.

Solar neutrinos from the decay of 8B have been detected at the Sudbury Neutrino Observatory (SNO) via the charged-current (CC) and neutral-current (NC) reactions on deuterium and by the elastic scattering (ES) of electrons. The CC reaction is sensitive exclusively to electron neutrinos, the NC reaction is sensitive to all neutrino species, while the ES reaction also has a small sensitivity to muon and tau neutrinos. These measurements provided strong evidence that neutrinos change flavor as they propagated from the center of the Sun to the Earth at the 5.3σ level. It will also be shown that a global solar neutrino analysis of matter enhanced neutrino oscillations of two active flavors strongly favors the large mixing angle solution.

FUJIWARA M. — 2004 г.

The Gamow—Teller (GT) states in 58Cu have been studied by the 58Ni( 3He, t + p) and 58Ni( 3He, t + γ) coincidence experiments at E( 3He) = 450 MeV and θ = 0°. Proton emissions from the GT states in 58Cu to the hole states in 57Ni have been observed with solid-state detectors in coincidence with high-energy tritons measured with a magnetic spectrometer. For the first time, the γ-ray emissions from the excited states in 58Cu and in 57Ni, following the 58Ni( 3He, t + p) reaction at intermediate energies, have also been observed in coincidence with tritons. The wave functions of the T = 1 and T = 2 GT states with the f —1 7/2 neutron—hole configuration are inferred to be strongly coupled to 2p—2h configurations, making

AKIMUNE H., DAITO I., EJIRI H., FUJIMURA H., FUJIWARA M., HARA K.Y., ISHIKAWA T., ITOH M., ITOW Y., KAWABATA T., KOBAYASHI K., NAKAMURA M., NORO T., OBAYASHI E., SAKAGUCHI H., SAKEMI Y., SHIOZAWA M., TAKEDA H., TAKI T., TAMII A., TOYOKAWA H., TSUKAHARA N., UCHIDA M., YAMADA T., YASUDA Y., YOSHIDA H.P., YOSOI M., ZEGERS R.G.T., НАГА К. — 2004 г.

Decay particles from the s-hole states in 11B and 15 N have been measured in coincidence with the quasifree 12C(p, 2p) and 16O(p, 2p) reactions at E p = 392 MeV Triton decay was found to be dominant for the 11B(s-hole) state and also found to be larger than α decay for the 15N(s-hole) state despite its smaller Q value compared to α decay. Measured decay branching ratios are discussed in comparison with the results of statistical-model, SU(3)-model, and shell-model calculations. The energy spectra around the s-hole states in both 11B and 15N exhibit some bump-like structures, which can be qualitatively explained by recent shell-model calculations for both nuclei.

CHKHAIDZE L.V., DJOBAVA T.D., KHARKHELAURI L.L., KLADNITSKAYA E.N., KUZNETSOV A.A. — 2004 г.

The directed (in-plane) flows of protons, pions and projectile light fragments (d,t, 3He, 4He) have been observed by investigating the dependence of the mean transverse momentum in the reaction plane (p x) on the rapidity y in the c.m. system for CC collisions at a momentum of 4.2 GeV/с per nucleon. The comparison of our in-plane-flow results of protons with flow data for various projectile/target configurations was made using the scaled flow F s = F/(A P l/3 + A T 1/3). F 8 demonstrates a common scaling behavior for flow values from different systems. From azimuthal distributions of protons and π - mesons the out-of-plane (squeeze-out) flow effects have been observed and the parameter a 2 (the measure of the anisotropic emission strength) have been extracted. The Quark—Gluon String Model reproduces quite well the experimental results.

DOROKHOV A.E., RADZHABOV A.E., VOLKOV M.K. — 2004 г.

Masses and interactions of light mesons are described in the framework of the model with the chiral invariant SU(2) x SU(2) four-quark interaction.The nonlocal kernel of the interaction is chosen in the form that ensures the absence of ultraviolet divergences in the Feynman diagrams and poles in the quark propagator. Within this model we demonstrate that in the chiral limit the pion mass equals zero and the Goldberger—Treiman relation is fulfilled. The sigma-meson mass and the widths of strong decays ? > ??, ? > ?? are estimated.

ADAMIAN G.G., ANTONENKO N.V., JOLOS R.V., PALCHIKOV YU. V., SCHEID W., SHNEIDMAN T.M. — 2004 г.

A cluster approach is applied for describing the decay out phenomenon of the yrast superdeformed states for mass region A ≈ 190.

ABRAMOV D.I., GUSEV V.V., PONOMAREV L.I. — 2004 г.

The reduced adiabatic hyperspherical (RAHS) basis suggested previously is used for the calculation of elastic and spin-flip cross sections in the processes (αμ) F + a — (αμ) F' + a, a = (p,d,t), for collision energies 10 -3 ≤ ε ≤ 10 2 eV. The rapid convergence of the method is demonstrated: to achieve the accuracy ~ 1% in the calculated cross sections it is enough to use N ≤ 10 of the basis RAHS functions. The comparison of the obtained results with the previous ones is presented.

БРАГУТА В.В., ЛИХОДЕД А.А., ЧАЛОВ А.Е. — 2004 г.

Рассматривается зависимость T-нечетной корреляции ξ = q · [p π х p l]/m 3 K распадов K + → π°l +νγ, l = e, μ, от параметров эффективного лагранжиана. Показано, что исследуемая величина является эффективной с точки зрения поиска новой физики в векторном и псевдовекторном секторах исследуемого лагранжиана. В скалярном и псевдоскалярном секторах лагранжиана исследование T-нечетной корреляции не позволяет существенно улучшить имеющиеся в настоящее время ограничения на параметры различных расширений СМ.

CHKHAIDZE V., DJOBAVA T.D., GARSEVANISHVILI V.R., KHARKHELAURI L.L., KLADNITSKAYA E.N., KURATASHVILI G.O., KUZNETSOV A.A. — 2004 г.

The inclusive spectra of pions produced in CC and CTa collisions at a momentum of 4.2 GeV/c per nucleon are analyzed in terms of light-front variables ξ and ζ. The phase space of the secondary pions is divided into two parts with very different angular and momentum distributions. In one of these parts the thermal equilibrium assumption seems to be in a good agreement with the data. Corresponding temperatures T are extracted, and their dependence on (A P A T) 1/2 is studied: T decreases linearly with increasing (A P A T) 1/2. The results are compared with the predictions of the Quark—Gluon String Model (QGSM). The QGSM satisfactorily reproduces the experimental data.

SOKALSKI I.A. — 2004 г.

The ANTARES project aims to build a deep underwater Cherenkov neutrino telescope in the Mediterranean Sea. Currently the experiment is in the construction phase and has recently achieved two important milestones. The electro-optical cable to shore and the junction box that will distribute power to detector strings and allow data transmission have been deployed at the sea floor. A prototype string and a string for environmental parameter measurement have been deployed, connected to the cable using a manned submarine. Data have been sent to shore. The final ANTARES detector consisting in 12 strings each equipped with 75 photomultiplier tubes is planned to be fully deployed and taking data by the end of 2006.

AYNUTDINOV V.M., BALKANOV V.A., BELOLAPTIKOV I.A., BEZRUKOV L.B., BUDNEV N.M., CHENSKY A.G., CHERNOV D.V., DANILCHENKO I.A., DOMOGATSKY G.V., DYACHOK A.N., DZHILKIBAEV ZH.-A. M., GAPONENKO O.N., GRESS O.A., GRESS T.I., KLABUKOV A.M., KLIMOV A.I., KLIMUSHIN S.I., KONISCHEV K.V., KOSHECHKIN A.P., KULEPOV V.F., KUZMICHEV L.A., KUZNETZOV VY. E., LUBSANDORZHIEV B.K., MIKHEYEV S.P., MILENIN M.B., MIRGAZOV R.R., MOISEIKO N.I., OSIPOVA E.A., PANFILOV A.I., PAN’KOV G.L., PAN’KOV L.V., PARFENOV YU. V., PAVLOV A.A., PLISKOVSKY E.N., POKHIL P.G., POLECSHUK V.A., POPOVA E.G., PROSIN V.V., ROSANOV M.I., RUBTZOV V. YU., SEMENEY YU. A., SHAIBONOV B.A., SPIERING CH., STREICHER O., TARASHANSKY B.A., VASILIEV R.V., VYATCHIN E.A., WISCHNEWSKI R., YASHIN I.V., ZHUKOV V.A. — 2004 г.

Present status of the Baikal Neutrino Experiment and present results of a search for upward going atmospheric neutrinos, WIMPs, and magnetic monopoles obtained with the detector NT-200 are reviewed. The results of a search for very high-energy neutrinos are presented as well. An upper limit on the v e + ν μ + ν τ neutrino diffuse flux of Ε 2Φ(Ε) < 1.3 x 10 -6 cm -2 s -1 sr -1 GeV within a neutrino energy range 10 4—10 7 GeV is obtained, assuming an E -2 behavior of the neutrino spectrum and a flavor ratio v e : ν μ : ν τ = 1:1: 1. We describe the moderate upgrade of NT-200 planned for the next years and present a possible detector on the Gigaton scale.

ARNABOLDI C., ARTUSA D.R., AVIGNONE F.T., BALATA M., BANDAC I., BARUCCI M., BEEMAN J., BROFFERIO C., BUCCI C., CAPELLI S., CARBONE L., CEBRIAN S., CREMONESI O., CRESWICK R.J., DEWAARD A., FARACH H.A., FASCILLA A., FIORINI E., FROSSATI G., GIULIANI A., GORLA P., HALLER E.E., IRASTORZA I.G., MCDONALD R.J., MORALES A., NORMAN E.B., NUCCIOTTI A., OLIVIERI E., PALMIERI V., PASCA E., PAVAN M., PEDRETTI M., PESSINA G., PIRRO S., POBES C., PREVITALI E., PYLE M., RISEGARI L., ROSENFELD C., SISTI M., SMITH A.R., TORRES L., VENTURA G. — 2004 г.

The CUORICINO ββ-decay detector is an array of 62 TeO 2 bolometers; 44 are 5 x 5 x 5-cm crystals made with natural tellurium (33.8% 130Te). There are 18, 3 x 3 x 6-cm crystals, 14 of which are made of natural tellurium, 2 are isotopically enriched to 75% in 130Te, and 2 are enriched to 82.3% in 128Te. The total mass of 130Te is ~11 kg. The background rate is 0.23 ± 0.04 counts/keV/kg/yrin the energy interval 2480 to 2600 keV. During the cooling process, some of the wires became disconnected and only 32 of the large and 16 of the smaller crystals could be read out. The data presented here come from 29 of the 5 x 5 x 5-cm crystals containing 6.2 kg of 130Te. The new limit on the half-life is T 0v 1/2 → 5 x 10 23 yr, corresponding to an effective Majorana mass of the electron neutrino, (m v), between 0.42 and 2.05 eV, depending on the nuclear model used to analyze the data.

BARABASH A.S. — 2004 г.

The possibilities of NEMO techniques forfuture neutrinoless double-beta decay experiments are discussed. The main idea is to have a realistic program with planned sensitivity for a half-life measurement on the level of ~(1.5—2) x 10 26 yr (sensitivity to neutrino mass ~0.04—0.1 eV). It is argued that it can be achieved using the improved NEMO technique to study 100 kg of 82Se. A possible scheme of a future SUPERNEMO detector and its main characteristics are presented. Such detector can also be used to investigate 0νββ decay in 100Mo, 130Te, and 116Cd with a sensitivity of up to ~(2—5) x 10 25 yr or with sensitivity to neutrino mass of ~0.04—0.26 eV

AALSETH C.E., ANDERSON D., ARTHUR R., AVIGNONE III F.T., BAKTASH C., BALL T., BARABASH A.S., BRODZINSKI R.L., BRUDANIN V.B., BUGG W., CHAMPAGNE A.E., CHAN Y.-D., CIANCIOLO T.V., COLLAR J.I., CRESWICK R.W., DOE P.J., DUNHAM G., EASTERDAY S., EFREMENKO YU. V., EGOROV V.G., EJIRI H., ELLIOTT S.R., ELY J., FALLON P., FARACH H.A., GAITSKELL R.J., GEHMAN V., GRZYWACZ R., HAZMA R., HIME H., HOSSBACH T., JORDAN D., KAZKAZ K., KEPHART J., KING III G.S., KOCHETOV O.I., KONOVALOV S.I., KOUZES R.T., LESKO K.T., MACCHIAVELLI A.O., MILEY H.S., MILLS G.B., NOMACHI M., PALMS J.M., PITTS W.K., POON A.W.P., RADFORD D.C., REEVES J.H., ROBERTSON R.G.H., ROHM R.M., RYKACZEWSKI K., SABOROV K., SANDUKOVSKY V.G., SHAWLEY C., STEKHANOV V.N., TORNOW W., VAN DE WATER R.G., VETTER K., WARNER R.A., WEBB J., WILKERSON J.F., WOUTERS J.M., YOUNG A.R., YUMATOV V.I. — 2004 г.

The proposed Majorana double-beta decay experiment is based on an array of segmented intrinsic Ge detectors with a total mass of 500 kg of Ge isotopically enriched to 86% in 76Ge. A discussion is given of background reduction by: material selection, detector segmentation, pulse shape analysis, and electroformation of copper parts and granularity. Predictions of the experimental sensitivity are given. For an experimental running time of 10 years over the construction and operation of the Majorana setup, a sensitivity of T'0/ 2 ~ 4 x 10 27 yr is predicted. This corresponds to (m u) ~ 0.003—0.004 eV according to recent QRPA and RQRPA matrix element calculations.

APRAHAMIAN A. — 2004 г.

Low-lying Κ π = 0 + bands are one of the most fundamental excitation modes in the spectra of deformed nuclei, however, very little is known about the nature of these excitations. We report on some new lifetime measurements using the GRID technique at ILL, and high-precision (p, t) reactions to elucidate the character of low-lying Κ π = 0 + bands in deformed nuclei. We also present results from a recent calculation on the nature of 0+ states using the projected shell model.

MANUEL O. — 2004 г.

Measurements are needed of low-energy antineutrinos generated by possible neutron decay at the core of the Sun. The measurement will test the validity of a proposal that solar luminosity, solar neutrinos, and the outpouring of H + ions from the solar surface are the products of a chain of reactions triggered by neutron emission from the solar core. Inverse β decay of 87-d 35 S, induced by capture of low-energy antineutrinos on 35 Cl, is a likely candidate for this measurement.

LUKYANOV S.M., PENIONZHKEVICH YU. E. — 2004 г.

Experimental studies of neutron drip line nuclei are introduced. The neutron drip line in the oxygen— magnesium region has been explored by the projectile fragmentation of a 48Ca beam. New neutron-rich isotopes, 34Ne and 37Na, have been observed together with some evidence for the particle instability of 33Ne and 36Na. Recent data on mass measurements of neutron-rich nuclei at GANIL and some characteristics of binding energies in this region are discussed. Nuclear binding energies are very sensitive to the existence of nuclear shells and together with the measurements of instability of doubly magic nuclide 28O they provide information on changes in neutron shell closures of very neutron-rich isotopes from carbon up to calcium. The conclusion about a rearrangement in neutron shell closures is given. The spectroscopic measurements can reveal details of the underlying microscopic structures, the in-beam γ-ray spectroscopy is an effective tool to check for shell closures. The results on the 7-ray energies of the first 2+ level in even—even nuclei for N range 12—32 are discussed. The strength of N = 20 and N = 28 shells is variable in the region from carbon up to magnesium.

CHANDRA R., CHATURVERDI K., DHIMAN S.K., DIXIT В.M., RAINA P.K., RATH P.K., SHUKLA A., SINGH A.J. — 2004 г.

The quality of Hartree—Fock—Bogoliubov wave functions is tested by comparing the theoretically calculated results with the available experimental data for a number of spectroscopic properties like yrast spectra, reduced B(E2) transition probabilities, quadrupole moments, and g factors for the nuclei involved in 2νββ decay. It is observed that the np interactions vis-a-vis the deformations of the intrinsic ground states of medium-mass nuclei play a crucial role in the fine tuning of the nuclear matrix elements.

DRACOS M. — 2004 г.

The OPERA (Oscillation Project with Emulsion-tRacking Apparatus) experiment aims to observe an unambiguous ν μ ↔ ν τ oscillation in the parameter region allowed by previous experiments. The OPERA detector will be installed in the underground Gran Sasso Laboratory, 732 km far away from CERN where the CNGS (CERN Neutrino beam to Gran Sasso) ν μ beam will be produced. The signature of the presence of ν τ’s in the ν μ beam will be the detection of τ leptons produced by ν τ interactions. Nuclear emulsions will be used for precise event reconstruction, while electronic detectors will be used for triggering.

SIMONOV YU. A. — 2004 г.

The light hadron spectrum as computed in nonperturbative QCD is reviewed and compared to lattice data and experiment. The mixing of mesons, hybrids, and glueballs is calculated in the Field Correlator Method. The strong decay mechanisms are found out in the method and compared to the known phenomenological models. The role of sea quarks (unquenched approximation) is studied analytically, using radially excited mesons as an example, and compared to experiment.