Half-lives andQ β measurements for new nuclei of89Tc and89mTc

Neutron deficient isotopes of⁸⁹Tc and^89mTc have been produced through the⁶⁰Ni(³²S,p 2n)⁸⁹Tc at 95 MeV and the⁵⁸Ni(³⁵Cl, 2p 2n)⁸⁹Tc reaction at 135 MeV. A rotating catcher foil system was used to collect the activities and transfer them to a measuring position for- spectroscopy. The half-lives of⁸⁹Tc and^89mTc were measured to be 12.8±0.9 s and 12.9±0.8 s, respectively. The total decay energy, Q_EC, for⁸⁹Tc was determined to be 7.51±0.21 MeV.The authors would like to express their thanks to technical staff of the Tandem Accelerator Center at the University of Tsukuba for their operation of the accelerator and assistance during the experiment. This work is partly supported by a Grant-in-Aid from the Japanese Ministry of Education, Grant No. 01790180.     

Resonance-enhanced multiphoton ionization spectroscopy of CH3 and CD3. Two-photon absorption selection rules and rotational line strengths of the ν3- and ν4-active vibronic transitions

To explore the possibility of K-level resolved, 2+1 resonance-enhanced multiphoton ionization (REMPI) processes of the methyl radical, the two-photon absorption selection rules and rotational line strengths of the 3₀¹ and 4₀¹ vibronic bands of the transition (n=3 or 4) were reported. Stringent selection rules, which were imposed upon these two-photon transitions, are the initial K″=3p (p=0,1,2,…), ΔK=±2, ΔU=±3, and ΔN=0,±1,±2 (O, P, Q, R, and S branches). The previously assigned 2₂² vibronic band of the methyl radical should be studied by the REMPI with a better spectral resolution and analyzed by the newly derived two-photon absorption selection rules and rotational line strength formulas.     

On the finite-time behaviour for nonlinear Schrödinger equations

Consider the nonlinear Schrödinger equationu _t –iu=f(u). Forf(u)=±|u|^1+p , ±i|u|^1+p , ±u|u| ^p (p>0), and the Dirichlet boundary or nonlinear boundary (including the Neumann boundary and the Robin boundary) conditions, we establish the local estimates for the timet to the solutions of the initial-boundary value problems. Being based up on these estimates, we investigate the blowing-up properties of the solutions.Research supported in part by the Youth Foundation of Sichuan Education Committee and the Natural Science Foundation of China     

Measurement of the forward-backward asymmetry ofe+e?→Z→ b[`(b)]b\bar b using prompt leptons and a lifetime tag

An analysis of inclusive production of K⁰ and the meson resonances K^*±(892), ⁰(770),f ₀(975) andf ₂(1270) in hadronic decays of the Z⁰ is presented, based on about 973,000 multihadronic events collected by the DELPHI detector at LEP during 1991 and 1992. Overall multiplicities have been determined as 1.962±0.060 K⁰ mesons, 0.712±0.067 K^*±(892) and 1.21±0.15⁰(770) per hadronic Z⁰ decay. The average multiplicities off ₀(975) for scaled momentum,x _p , in the range 0.05x _p 0.6 and off ₂(1270) for 0.05x _p 1.0 are 0.098±0.016 and 0.170±0.043 respectively. Thef ₀(975) and ⁰(770)x _p -spectra have similar shapes. Thef ₂(1270)/⁰(770) ratio increases withx _p . The average multiplicities and the differential cross sections are compared with the JETSET Parton Shower model. The model with default parameters fails to reproduce the experimental K⁰ momentum spectrum at low momentum, describes the K^*±(892) and ⁰(770)x _p -spectrum shapes, but significantly overestimates their production rates.(CICYT-AEN93-0832)     

The decay of the isotopes179Ir and180Ir

The probability for non-radiative (n.r.) excitations in muonic²⁰⁹Bi was determined from a ( ^–,)-measurement by comparing the intensities of muonic X-ray transitions in single and coincidence spectra. The values of P_n.r(3p1s)=(17.9±2.0)% and P_n.r.(3d1s)=(3.0±2.2)% were measured for the first time. The strength of the n.r. decay of the 2p-level was found to be (4.2±2.2)%. The n.r. transition probabilities of two subcomplexes of the (2p1s)-transition leading to different mean excitation energies are (3.2±1.8)% and (5.0±2.0)%, respectively.We are indebted to the following institutes or organizations for financial support: Bundesministerium ffir Forschung und Technologic der Bundesrepubfik Deutschland contract number 06 BN 271 (HP, PD, HH, FR, CR), Foundation for Fundamental Research on Matter (FOM) and the Netherlands Organization of the Advancement of Pure Research (NWO) (JK, CTAMdL, WL, AT) and the Schweizer Nationalfonds (LS).     

Total decay-energy measurement in the fusion reactions90Zr(89Y,p)178Pt and90Zr(89Y, α)175Ir

In the fusion reactions⁹⁰Zr(⁸⁹Y,p)¹⁷⁸Pt and⁹⁰Zr(⁸⁹Y,)¹⁷⁵Ir the sum energy of all emitted rays as well as the energy of the promptly emitted charged particle were measured. From these data the mass-excess values for the evaporation residues¹⁷⁸Pt and¹⁷⁵Ir were extracted to be(¹⁷⁸Pt)=(–32.4±1.1)MeV/c² and(¹⁷⁵Ir)=(–32.0±1.2) MeV/c². The method provides absolute mass values for nuclides far from stability which can be produced in fusion reactions as evaporation residues in the 1p or 1 channel. The sources of the experimental uncertainties of the method are discussed, and the potential for considerable improvements is outlined.Dedicated to P. Armbruster on the occasion of his 60th birthday     

Inclusive neutral vector meson production in hadronicZ0 decays

Results are reported of a study of neutral vector meson production in multihadronicZ ⁰ decays in the OPAL experiment at LEP. Pions and kaons have been identified by specific ionisation energy loss andK ^± andK ⁺ K ^– mass spectra have been fitted, in bins of the scaled momentum variablex _p , to combinations of resonance signals and non-resonant backgrounds. Rates are given forK ^*(892)° and ø(1020), and production cross sections are compared to the predictions of Monte Carlo models. Overall multiplicities have been determined as 0.76±0.07±0.06K ^*(892)° and 0.086±0.015±0.010 ø(1020) per hadronicZ ⁰ decay (the quoted errors are respectively statistical and systematic). Momentum dependent distortions of the mass spectra, possibly associated indirectly with Bose-Einstein effects, have prevented reliable measurement of the (770)° cross section in this study.     

The Β decay of the new isotope79Y

The neutron deficient isotope⁷⁹Y has been firstly identified and the decay properties were studied from-decay measurements in the reaction of⁵⁴Fe(²⁸Si,p2n at 92 MeV. Three rays of 152.5, 177.4, and 1106 keV were observed concerning the decay. The half life and Q_EC value were determined to be 14.9 ± 0.6 s and 7.12 ± 0.45 MeV, respectively. The decay scheme including spin-parity is discussed, and 5/2⁺ assignment for the ground state is proposed.We would like to thank to Dr. Y. Maeda for his valuable advice about the electroplating method of iron targets. We also thank to Mr. T. Maeda and Mr. S. Niiya for preparation of hardware for data-taking.     

X-rays from antiprotonic3He and4He

Antiprotonic X-rays from the helium isotopes have been observed at pressures of 36, 72, 375 and 600 mbar. The antiproton beam from LEAR with momenta of 309 and 202 MeV/c has been stopped at these pressures using the cyclotron trap. The X-rays were detected with Si (Li) and intrinsic Ge semiconductor detectors. Absolute X-ray yields were determined and the strong-interaction 2p shifts and the 2p and 3d broadenings measured to be _2p=(–17±4) eV, _2p=(25±9) eV and _3d=(2.14 ±0.18) meV for ¯p³He and _2p=(-18±2) eV, _2p =(45±5) eV and _3d=(2.36±0.10) meV for ¯p⁴He.The efforts of the LEAR staff and the help of P. Gauss from the CERN Cryogenic Group as well as the technical assistance of M. Dröge and M. Stoll are gratefully acknowledged. This work is part of the Ph.D. of one of us (M.S.), University of Karlsruhe (1987), KfK report no. 4222.     

Experimental determination of the rates of the excited muonic hydrogen charge exchange on helium

The data of the experiment with the H₂+⁴He mixture are analyzed in order to estimate muon transfer rates from the excited states of p atoms to helium. Experimental data turned out to be insensible to the transfer rates from the metastable 2s state. The rates forn=3, 4, 5 were found to be: ⁽³⁾=(2±7)×10¹⁰ s^–1, ⁽⁴⁾=(16±13)×10¹¹ s^–1, ⁽⁵⁾=(75±60) ×10¹¹ s^–1, respectively.     

Neutral strange particle production in neutrino and antineutrino charged current interactions on protons

The production of the neutral strange particlesK ⁰, and invp and charged current interactions is studied in an experiment with the Big European Bubble Chamber. Mean multiplicities are measured as a function of the event variablesE _v,W ² andQ ² and of the hadron variablesx _F,z andp _T ² .K ^*± (892) and ^*± (1385) signals are observed, whereas there is no evidence for ^*- (1385) production invp scattering. Forward, backward and total mean multiplicities are found to compare well with the predictions of an empirical model for deep-inelastic reactions in the case of the strange mesonsK ⁰ andK ^*± (892) but less so for the strange baryons , and ^*± (1385). The strange baryon multiplicities are used to obtain the decuplet to octet baryon production ratio and to assess the probabilities of auu orud system to break up.     

Corrections to cluster-radius scaling for branched polymers and percolation

We report analyses of series enumerations for the mean radius of gyration for isotropic and directed lattice animals and for percolation clusters, in two and three dimensions. We allow for the leading correction to the scaling behaviour and obtain estimates of the leading correction-to-scaling exponent . We find -0.640±0.004 and =0.87±0.07 for isotropic animals in 2d, and =0.64±0.06 in 3d. For directed lattice animals we argue that the leading correction has= or= ; we also estimate =0.82±0.01 and 0.69 ±0.01 ind=2, 3 respectively. For percolation clusters at and abovep _c, we find (p _c) =0.58±0.06 and (p>p _c)=0.84±0.09 in 2d, and (p _c)=0.42±0.11 and (p>p _c)=0.41 ±0.09 in 3d.     

Study of the spectrum of CH335C1 between 4250 and 4600 CM?1: thev2+v4 andv4+v5 rovibrational bands

About 2500 lines of CH₃ ³⁵Cl have been assigned. The strong xy Coriolis resonance between thev ₂ andv ₅ modes is quite visible between thev ₄+v ₄ ^±1 perpendicular band, centered around 4383 cm^–1, and thev ₄ ^±1 +v ₅ ^±1 perpendicular component, centered around 4475 cm^–1, with a crossing of upper energy levels allowing the observation of lines which are normally forbidden. Although not yet observed with certainty, because of the great density of lines of the spectrum, thev ₄ ¹ +v ₅ ^±1 parallel component is nevertheless detectable by its effects onv ₂+v ₄ ^±1 which is linked by Coriolis resonance to both components ofv ₄+v ₅. Moreover the spectrum is much complicated by many other resonances with weak bands which occur at level crossings: it is the case ofv ₂+3v ₆ ^±1 , connected tov ₂+v ₄ ^±1 by the well known Darling Dennison resonance which couplesv ₄ ^±1 and 3v ₆ ^±1 , and also ofv ₅ ^±1 +3v ₆ ^±1 connected tov ₄ ^±1 +v ₅ ^±1 by the same resonance; but this last case is complicated by an anharmonic resonance betweenv ₅ ^±1 +3v ₆ ^±1 and 2v ₃+3v ₆ ¹ . Two more perturbations occur on the K=–1 side ofv ₂+v ₄: a weak Coriolis resonance gives rise to one subband ofv ₁+v ₂ at a level crossing withv ₂+v ₄, and thev ₁+v ₅ band (linked of course tov ₁+v ₂ by the Coriolis resonance between thev ₂ andv ₅ modes) is quite visible and perturbs several subbands ofv ₂+v ₄ of high values of K through an anharmonic resonance. Moreover, the complex (3v ₅ ^±1 ,v+2v ₅ ⁰ , 2v ₂+v ₅ ^±1 , 3v ₂,v ₂+2v ₅ ^±2 , 3v ₅ ^±3 ) system of Coriolis-connected bands is linked to the bands studied in the present work by two Fermi resonances: one betweenv ₂+2v ₅ ⁰ andv ₁+v ₂, and the other one betweenv ₁+v ₅ and 3v ₅ ^±1 , whose several subbands have been observed on the low part of the spectrum. The values of all the band centres and of the different coupling constants have been estimated, but all these interactions make the line assignments and the interpretation of the spectrum very difficult.     

Note on the susceptibility exponent for two-dimensional percolation

Analyses of mean site content, mean bond content, mean perimeter and related quantities give a susceptibility diverging as (p _c –p)^–, with 2.41±0.025. This exponent disagrees with some earlier estimates but it is consistent with the (p _c –p)^–2.388... divergence predicted by the formulas of den Nijs, Nienhuis et al. and Pearson.     

Identified hadron production at high transverse momenta in p+ p collisions at $\sqrt{s_{NN}}=200$ GeV in STAR

We report the transverse momentum (p _T ) distributions for identified charged pions, protons and anti-protons using events triggered by high deposit energy in the Barrel Electro-Magnetic Calorimeter (BEMC) from p+p collisions at  GeV. The spectra are measured around mid-rapidity (|y|<0.5) over the range of 3<p _T <15 GeV/c with particle identification (PID) by the relativistic ionization energy loss (rdE/dx) in the Time Projection Chamber (TPC) of the Solenoidal Tracker at RHIC (STAR). The charged pion, proton and anti-proton spectra at high p _T are compared with published results from minimum bias triggered events and the Next-Leading-Order perturbative quantum chromodynamic (NLO pQCD) calculations (DSS, KKP and AKK 2008). In addition, we present the particle ratios of π ⁻/π ⁺, , p/π ⁺ and in p+p collisions.     

Isomeric transitions between shape coexisting states in iodine isotopes withA=115, 119 and 121

Applying delayed- r.f. coincidences and generalized centroid-shift analysis, nanosecond isomers in some odd-A iodine isotopes are studied in-beam. The reactions¹⁰⁶Cd(¹²C,p2n) and^116,118Sn(⁶Li,3n) have been used. The following half-lives were determined:T _1/2(565 keV)=0.50±0.10 ns andT _1/2(837 keV) =0.90±0.20 ns in¹¹⁵I,T _1/2(687 keV)=5.50±0.50 ns andT _1/2(2418 keV)=4.0±0.50 ns in¹¹⁹I as well asT _1/2(812 keV)=0.35±0.20 ns andT _1/2(445 keV)<0.10 ns=">¹²¹I. A systematics of the absolute probabilities for the transitions deexciting theg _9/2 9/2⁺ and _11/2 11/2 ₁ ^– band heads in^115–125I is presented and discussed.Partly supported by the Bulgarian National Research Foundation under contracts PH14, and PH31 and Kernforschungszentrum Karlsruhe, Stabsabteilung Internationale Beziehungen     

Inclusive production of φ-mesons in neutron-proton interaction at 30–70 GeV/c

A signal of the-K⁺K^– decays has been observed in neutron-hydrogen interactions at energies of 30–70 GeV in an experiment using the BIS-2 spectrometer. The longitudinal momentum spectrum in the forward region,x _F<0·1 atp _T<1 GeV/c, can be well described by a power law dependence (1–x _F)^N withN=4·28±0·42. Thep _T ² -spectrum has been parametrized by the exp(–Bp _T ² ) law with the exponentB=(3·02±0·55) (GeV/c)^–2. The extrapolation of the measured cross section to the full kinematic region yields a value of (220±85) b in agreement with measurements from the proton beams.     

Computer simulation of the nonequilibrium critical behavior of disordered two-dimensional Ising systems

We report the results of a computer simulation of the critical relaxation of the magnetization in the two-dimensional Ising model with nonmagnetic impurity atoms frozen at the lattice sites. We assume a square lattice of dimension 400² with spin concentrationsp=1.0, 0.95, 0.9, 0.85, 0.8, 0.75, 0.7. The Monte Carlo and dynamic renormalization group methods are used to determine the dynamical critical indexz as a function ofp: z(p): z(1)=2.24±0.07,z(0.95)=2.24±0.06,z(0.85)=2.38±0.05,z(0.8)=2.51±0.06,z(0.75)=2.66±0.07,z(0.7)=2.88±0.06. It is shown thatz(p) obeys a singular scaling law of the formz=A | ln (p–p _c) |+B withA=0.56±0.07,B=1.62±0.07.Omsk State University. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 8, pp. 83–88, August, 1994.     

Virtuality evolution and rapidity structure of a simplified parton shower

We have studied transverse momentum distributions for exclusive ⁰ muoproduction on protons and heavier nuclei at 2Q ²<25>². TheQ ² dependence of the slopes of thep _t ² andt distributions is discussed. The influence of the non-exclusive background is investigated. Thep _t ² -slope for exclusive events is 4.3±0.6±0.7 GeV^–2 at largeQ ². Thep _t ² spectra are much softer than inclusivep _t ² spectra of leading hadrons produced in deep inelastic scattering.Supported by Bundesministerium für Forschung und Technologie     

Study of the centrally producer ππ andK \bar K systems at 85 and 300 GeV/c

We have studied the andK systems centrally produced in proton proton collisions at 300 GeV/c and ⁺/p proton collisions at 85 GeV/c using the CERN spectrometer. Clear evidence forS ^*/f _o(975) production is observed. An analysis performed on the ^{+ –} mass spectrum in the 1.0 GeV region, using a coupled channel formalism, shows that it is possible to describe theS ^*/f _o(975) effect with one single resonance once interference of theS ^*/f _o(975) with theS-wave background is introduced. The resultingS ^*/f _o(975) parameters arem _o =979±4MeV,g =0.28±0.04,g _K =0.56±0.18 corresponding to a pole position on sheet II at (1001±2)–i(36±4) MeV. Evidence is also found for a structure having a mass of 1472±12 MeV and a width of 195±33 MeV.