1982 Vol. 6, No. 2
Display Method: |
The elementary construction and primary performance of an adjustable field driftchamber with sensitive area 20 cm×20 cm are discussed. We have obtained spatialresolution of 120 μm, time resolution (FWHM) of 5.3 ns and efficiency of above 99%.The amplitude is uniform in drift cell. The time-space correlation is linear and itsenergy resolution arrives 22.5% for X-ray of 55Fe.
A xenon lamp-fibre glass apparatus as a monitor system of counters of Mark-Jdetector has been built. There are 208 channels of fibre to photomultipliers of counters.The calibration of pulse amplitude of counters and the relation of time between coun-ters has been given. Due to the reference tube system, the stability of the apparatus has been improvedand the accuracy of measurement has approached to ±1%. After long time operation, we found that the apparatus are stable and reliabledesirable.
The most probable escape path (MPEP) between vacuums, determined with WKBmethod, is expressed by different functions corresponding to the classical solutions offield equations in Euclidean space or in Minkowski Space while the potential U ishigher or lower than the energy E respectively. But the WKB method will not be validnearby the turning point u=E. In this paper we give the equations satisfied in thevicinity of turning point by MPEP which connects E4 and M4 solutions. The energylevels of physical θ vacuums obtained in terms of periodic potential in winding numberspace are not equal to the energy of original vacuums. The MPEP and also the poten-tial depend on positions of energy levels. Conversly, the energy levels are determined bypotential. We explain how to account this selfconsistently.
In this paper we discuss the transverse momentum QT. spectra and the dependenceof
〈QT2〉 on Q2 of the μ pair for massive μμ production at high energy proton-nucleoncollisions. It is shown that if we combine the contributions of the subprocesses ofvalence-valence quark hard scattering with the 0(as) QCD calculations and assume theinitial parton intrinsic transverse momentum
〈PT〉0.3 GeV/c, then the calculatedresults get a better fit to these experimental data when we use the parton distributionfunctions from deep inelastic scattering on nucleons.
The theory of the π-nucleus scattering developed by Brown and Weise is generalizedto study the (π, N) reactions. The differential cross section of the 4He(π-, n)3H atthe 100, 200, 290 MeV is calculated by using this method. The results obtained are discus-sed.
In this paper we investigate and obtain the large momentum behavior of the B.Swave function of the 1++ meson and the electromagnetic transitional form factor FA1π.(q2) using the operator product expansion and the renormalization group approach.The possible experimental tests are also discussed succinctly.
In this paper we discuss the relation between the normal static and sphericallysymmetric solution of classical SU(N) Yang-Mills equation in the wide sense and thestatic and spherically symmetric external source. We show that: (i) The normalstatic and spherically symmetric solution must be Coulombian for the diagonalizablenon-uniform static and spherically symmetric external source, if in some sphericall shell r1＜r＜r2 the source is extended in N or (N-1) order; (ii) It is impossible toconfine the normal static and spherically symmetric solution which is not strict sphe-rically symmetric in finite region.
The calculation of the microscopic optical potential (MOP) in symmetric nuclearmatter using semi-microscopic nuclear matter approach was discussed previously. Inthis paper, the same method is extended to the study of the asymmetric nuclear matter.The theoretical formulae of the MOP is derived and the results of calculations are pre-sented. The dependence of the MOP on asymmetric factor α is also analysed. Finally,the five kinds of the different parameters of Skyrem interactions Ⅱ--Ⅵ are used andcompared with the experimental data to study how well these Skyrme interactions canwork for our purpose. The calculated results show that the conclusions for symmetricnuclear matter are suitable for asymmetric nuclear matter as well.
In the original version of IBM, only the existence of p-p boson and n-n boson isassumed. Later on, Elliott and White attempted to consider the p-n boson and em-ployed the isospin. The above mentioned three kinds of bosons form an isospin triplet.They advocated that the effective Hamiltonian is isospin SU(2) invariant. In thisarticle, we have the view that the Hamiltonian contains besides the iso-invariant partalso a non-iso-invariant part. From the fact that IBM accounts for the low lying levelsof nuclei suceessfully, we can make some conclusion about the relations among the pa-rameters occuring in the effective interaction. The original version of IBM andElliott-White's theory are limiting cases of the present work. If IBM can also be ap-plied to odd-odd nuclei, a special type of spectrum can be pridicted. It seems that suchkind of spectrum do appear in the experiments for a number of odd-odd nuclei.
In this paper we treat the octupole states in even-even nuclei using a system consisting of f- boson and N—1个s+、d+ bosons, SO(6) limiting case is emphasized and theanalytic relations for energies and electromangnetic transition rates are derived. Andfinally the two particle states are briefly discussed.
We consider the fission process from saddle point to scission point as a non-equili-brium transport process obeying the Master equation, which can be reduced into theform of Fokker-Planck equation approximately. Taking the mass asymmetry coordinatex as the macrovariable, the nuclear fission can be considered as a diffusion process inx space, the drift velocity v(x,t), which is a non-linear. function of x, is proportionalto the gradient of the potential surface of fission nucleus in x space. The kinetics ofnuclear deformation from saddle point to scission point is represented by the variationof v(x,t) with time t phenomenologically. Assuming the mass distribution at saddlepoint is a symmetric one, and to solve the Fokker-Planck equation by means of Su-zuki's scaling limit approximation method, we get a solution which becomes a double-Gaussian asymmetric distribution on the potential valley after a time interval longenough, the width of mass distribution is proportional to nuclear temperature and in-versely proportional to relative depth of the potential valley. In the case of 235U(n,f),the time interval evaluated from saddle point to scission point would be larger than1.6×10-21 second, while it has arrived at the statistical equilibrium state. The Fong'sstatistical theory of nuclear fission is proved to be the case of stationary solution of theFokker-Planck equation exactly.
The structure of the nucleon-meson coupling is discussed on the basis of QCDperturbation theory. The transition amplitude for the Nucleon-Nucleon (Baryon) +Meson is obtained in the spherical cavity approximation of MIT bag model. From theanalysis of these amplitude (probability) it shows that the exchange of heavy mesonsof the first excited state (B, δ, A1,...) and the 2π exchange (intermediate states N*.△*) are important in the zero range N-N interaction. However, the one-pion and onep、ω. etc do not appear.
It is shown that the generator coordinate method previously developed for study-ing nuclear collective excitation spectra can also be applied to investigate the relativetranslational motion in heavy-ion collsions. The effective hamiltonion for such motionin familiar form is obtained under quasi-classical approximation.
The Kaluza type interactions including Einstein's gravitation, Abelian and non-Abelian gauge fields, and their unification can be induced by the quantum effects ofsome kinds of fundamental fields in the background metric on the principal fibrebundle. Therefore, the Kaluza type interactions can be regarded as some kinds ofeffective interactions rather than fundamental ones.
The 2-dimension fields for the constant direction magnetized quasi-segment-ed, trapezoidal and plane head quasi-segmented multipiece ring system are analysedusing harmonic analytical method as the principle of "uniform magnetization". Someprecise analytical expression are given. As an example, magnetic field gradient of 16-pieces quasi-segmented, trapezoidal quadrupole is calculated and compared with a 16-pieces plane head segmented quadrupole.
Lifetimes of excited states in the even parity yrast, γ-type vibrational and nega-tive parity Band in 76Kr were measured by the Doppler shift attenuation method. Thelifetimes or composite feeding times of thirteen excited states in 76Kr were determined.The transitions in each of the three band are highly collective, and the transition in-tensity is the order of 100 single particle units or more.
- A SCOAP3 participating journal - free Open Access publication for qualifying articles
- Average 24 days to first decision
- Fast-track publication for selected articles
- Subscriptions at over 3000 institutions worldwide
- Free English editing on all accepted articles
- Impact factor of Chinese Physics C is 2.463 in 2019
- Chinese Physics C: 2019 Reviewer Awards
- FUTURE PHYSICS PROGRAMME OF BESIII
- Happy New Year !
- 2019 CPC Top Reviewer Awards