1998 Vol. 22, No. 12
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60MeV /u 18O ion beam delivered by the Heavy Ion Research Facility in Lanzhou (HIRFL) bombarded the natural tungsten targets. The 186Hf was produced by multinucleon transfer reacions. The hafnium fraction was separated radiochemically from the mixture of tungsten and the reaction products. The γ activity was measured with a HPGe detector. The growth and decay of 186)Ta γ-rays has been observed, which indicates the (186)Hf as a parent of 186Ta were produced. The half-life of 186Hf has been determined to be (2.6±1.2)min.
In this paper, the target-dependence of neutron-proton ratio of the projectile-like fragments, prepuced in the peripheral heavy-ion collisions, is discussed based on the comparison between the experimental results and the isospin dependent QMD model calculahons.
The average independent production cross sections of the radioactive Hg isotopes in the mass range of 180 to 209, produced in 600MeV-18O bombardment on (nat)Pb (thick target), were measured. The production mechanisms for the Hg-isotope products at different mass section were discussed by means of a comparison with the Hg-isotope distribution obtained in 600 MeV proton bombardment on natPb. The measlesment results were also compared with the Ir-isotope distribution observed from relativistic 197Au projectile fragmentation reaction. The present experiment results showed that using intermediary-energy heavy ion beams bombarding neutron-rich heavy targets is a favourable reaction to produce neutron-rich heavy residues.
The effect to low energy neutrons from monoenergetic neutron source on achvation cross section measurements was analysed and studied. This analysis was proved by the measured neutron spectra of T(d,n)4He and D(d,n)3He neutron sources. Finally the cross sections for 58Ni(n,p)58Co and 64Zn(n,p)64Cu reaction were given.
The decay of 83Sr has been reinvestigated using γ singles and γ-γ-t coincidence measurement. The number of γ transitions assigned to 83Sr decay has been expanded from 102 to 196.19 new levels of 83Rb are added to the old level scheme and 8 formerly adopted levels are denied by the present study. New data of branching ratio, logft value and spin-Parity are also obtained.
Properties of a new kind of double metal contact GaAs semiconductors have been investigated. We measured the spectra of 5.48MeV α particles from 241Am,122keV photons from 57Co and 2.27MeV MIPs from 90Sr and compared the cce and FWHM of a 3×3mm2 GaAs detector before and after 1300rad 662keV photons from 137Cs. The test results show that these new Metal-Semiconductor-Metal(MSW) structure semiconductor detectors not only have good particle detection ability at room temperature but also have excellent radiation hardiness.
An integrable model with non-period boundary condition is constructed by use of factorized L operator. Taking trigonometric limit and scalar limit to the transfer matrix, we obtain the classical Hamiltonian of the n dimentional system (n is odd number). The result shows that this integrable system is similar to those found by Calogero et al.
The modified Seiberg-Witten monopole equations on a three-manifold are presented in this paper. Special analytic solutions to these eqations are given. These eqations are invariant under the conformal transformation.
The K+ production and flow in relahvistic heavy-ion collisions are investigated with the self-consistent relahvistic Boltzmann-Uehling-Uhlenbeck (RBUU) approach. The results show that the kaon flow is sensitive to both the kaonnucleon sigma term ∑KNand the equation of state (EOS) of nuclear matter. We find that anti-flow appears at cerhan large impact parameter, which can provide more definite information of the magnitude of ∑KN We have also analyzed the dependence of the total K+ production probability and the contributions from different channels on the EOS and the ∑KN. The sensitivity to the nuclear equation of the state and ∑KN is different for different channels. Overall, the contribution from N△ channel is the most important.
We calculate one-loop corrections to the top-quark decay width г(t→W+ b)from PGBs (Pseudo-Goldstone bosons) in the MWTCM (multiscale walking technicolor model). The cormctions are found so large that г(t→W+ b) is decreased largely. If topeolor is further introduced into MWTCM, г(t→W+ b) is enhanced, and the PGBs' cormctions in the topeolor assisted MWTCM may reach -7% for certain parameters in this model, which might be observable in the experiments.
Elastic differential cross sections for K+ mesons scattered from 12C and 6Li targets at an incident momentum of 715 MeV/c and from(12). 40Ca targets at an incident momentum of 800 MeV/c have been studied in this paper. The method of the eikonal phase shift with the first-order correction including the deflection effect due to the coulomb field has been used in the work. By the fitting the theoretical differentical cross sections with the corresponding experimental results we have got the optimum optical potential parameters, which provides some Kind of bases for the microscopic shudy of K+ elastic scattering. We gained the total cross sections for the correspondiny scatterings by using the ophcal potential, and compared itwith the experimental data.
BCS theory is used to calculate the moments of inertia (Mol) of odd-A and even-even rare-earth nuclei. It is found that the large fluctuations of the odd-even differences in MoI can be repreduced through the BCS calculations, although the MoI values calculated both for odd-A and even-even nuclei are systematically smaller then the experimental data. Contrary to the common assertion that the MoI value of odd-A nuclei are some 15% larger than that of the neighboring even-even nuclei in the BCS theory, our results confirm the conclusions made by Gregory Volkov over two decades ago. It seems helpful to understand the appearance of normally deformed identical bands in an odd-A nucleus and its evenreven neighbors Under the mean-field (BCS) approximation.
The relation between the leptonic decay width of J/ψ and the color screening mass at finite temperature is studied by using different quark binding potentials. The leptonic decay behaviour of J/ψ in the hot and dense matter is obtained.
The possibility and method of designing a high luminosity collider with negative momentum compaction factor (αp<0) lattice are studied. As a practical example, the feasibility of adopting the αp<0 lattice for a τ-charm factory is discussed.
The physics issues involved in the lattice design of Beijing Tau-charm Factory (BTCF) storage ring are investigated and studied. A lattice that takes the high luminosity mode as the first priority and is compatible with monochromator mode and polarized beam collision mode is proposed. It's a feasible design with large dynamic aperture for the high luminosity mode and acceptable Touschek lifetime for the monochromator mode.
The beam dynamics of coupled bunch instability is studied using simulation method in this paper. The code SCBI (Simulation of Coupled-Bunch Instabilities) is developed. ms code can be used to study the multi-bunch instabilities including the effects of long range and mediate range wake field due to RF HOMs, resistive wall and other cavity shape element along the ring. The simulation results using SCBI are compared with those of ZAP when bunches are symmetrically distributed, showing a good agreement with each other. The code SCBI has been used to study the multi-bunch instability in BEPCⅡ.
We have investigated structrues and topography features of sputered graphite surface using scanning electron microscopy (SEM) and transmission electron microscopy (TEM), and demonstrated that carbon nanotubes can be grown up by sputtered-atom deposition on a protrusion of topography feature.
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