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1.
Experimentally, it is much easier to measure structure functions at fixed hadron energy Eh, rather than at fixed Q2. We prove the sum rules
?10dx F3|fixed Eh= 3 1 ? (1+hNS) αs(s)π,
?10dx F2|fixed Eh= 3nf16+3nf1?171+44nf9(67?12nf+ hSαs(s)π + Kαs(s)π0.75
,
hNS=43(16π2 ? 58),
hS=416+3nf (2π2 + 16π2nf?6512?572nf).
Here s = 2mpEh and F2,3 are the standard functions for scattering of neutrinos on an isoscalar target. K is an unknown constant, and the corrections to the sum rules are O(αs2), O(αs1.75), respectively.  相似文献   

2.
The low temperature mobility μ limited by charged impurities is calculated by solving the equation for the relaxation rate previously derived. The calculated μ behaves like μ = 2.03 κ2 (kBT)32e?3z?2ns?1m1?12 In [38.2κ2m112 (kBT)52/z2 e4h?ns] for lowest concentrations ns<1011cm?3 for Ge and
μ = 0.360h?12κ(kBT)14(ze)?1ns?12m1?34
for intermediate concentrations ns ~ 1012?1014cm?3.  相似文献   

3.
The electron-exciton inelastic collision cross sections for the different semiconductors CdS, ZnO, CdSe, Si, Cu2O, CuCl, CuBr and CuI have been calculated in the Glauber approximation. The transitions 1s–2s, 1s–3s, 1s–2p and 1s–3p have been considered. The calculations are carried out as function of the different available values of σ =m1em1h where m1e and m1h are, respectively, the electron a corresponding semiconductors.  相似文献   

4.
The fluorescence and absorption spectra of Eu3+ in K5Eu(MoO4)4 have been measured at 300 K and 77 K. The fluorescence lifetime of the 5D0 state is 1.4 ms at 300 K. The largest cross section σ(5D07F2(4)) = 1.3 × 10?21 cm2 and the removal of degeneracies require to replace the nearest neighbour D3d symmetry of Eu3+ by the effective symmetries C1, C2 and Cs of the whole unit cell. It is shown that C1 dominates because of the statistical distribution of K+ and Eu3+. The corresponding inhomogeneous broadening is observed at 77 K.  相似文献   

5.
By using different gauges, the relativistic rates for the Kαα2(1s?2→2s?12p12?1) and the Kα2h(1s?2→1s?12p12?1) transitions are calculated for Ne, Ar, Ca, Fe and Cu. The problem in the use of the single configuration HF model is discussed.  相似文献   

6.
The polarized excitation and emission spectra of the U6+ molecular centers giving the most intense emission lines at 18 940 cm?1 and 19 285 cm?1 are presented and analyzed in detáil. From the polarization experiments, it is shown that the symmetry of the centers is C4v and that the symmetries of the observed electronic states are Γ2, Γ1 and Γ5. Finally, an electronic model is proposed which associates the emission and excitation lines of the U6+ centers in the visible region to transitions between the fundamental state Γ1 (6p6, 1S) and the states of the excited configuration 6p5(2P32) 7s.  相似文献   

7.
The reactions pp → pp and pp → Δ++n with polarized beam and/or polarized target are currently under investigation at the Argonne ZGS. We discuss how to interpret various measured quantities in terms of amplitudes whose behavior is familiar (as functions of s, t). For pp total cross sections and elastic scattering, Argonne measurements will yield Im ?2 (s,t = 0) and the rather complicated combination 2|?5|2 + Re (?1?21 ? ?3?41), where ?i (i = 1, … 5) are conventional s-channel helicity amplitudes. The forward direction (t = 0) is of special interest. We find that for both pp → pp and pp → Δ++n, polarized beam — polarized target experiments plus the rather general (testable) assumption that amplitudes with the same s-channel helicity flip quantum numbers are proportional, are sufficient to fully determine all non-vanishing amplitudes at t = 0. Numerical estimates of some observables, based on calculations in a specific model, are also given.  相似文献   

8.
The dependence of inclusive cross sections of the production of hadrons pp → hX on p (and also on x and √s) is calculated at high energy in the region of small p ? 1–2 GeV. The model of production and decay of quark-gluon strings is used under the simplest assumptions about the k dependence of the quark distributions in nucleons ~ exp(?γ1k2) and about the form of the string fragmentation function G?hexp[?γh(p ? zk)2] where γ1 and γh are some constants. The theory reproduces all existing experimental data and yields the “seagull effect” for the dependence of 〈p〉 on x. Predictions are given for the p dependence of the spectra of π± mesons produced at high energies at SPS and other future colliders.  相似文献   

9.
The electrical resistivity and Hall coefficient of Zn3P2 have been measured for single crystal and thin polycrystalline film samples which were annealed over a range of equilibrium vapor compositions and temperatures. The room temperature electrical resistivity of single crystal samples annealed at 573 K varied from approximately 105Ω-cm for single crystals heated in equilibrium with zinc to 10 Ω-cm for those annealed in a phosphorus rich ambient. Hall measurements indicate that a variation in carrier concentration is responsible for these changes. The experimentally observed dependence of carrier concentration [h° ], (cm?3) on phosphorus pressure is given by [h°] = 1.32 · 1016 [p(P4)]0.13 for samples annealed at 573 K. The experimentally determined pressure dependence is in good agreement with a model based on phosphorus interstitials acting as acceptors. The pressure and temperature dependence of the carrier concentration yield the equilibrium constant KI for the formation of interstitial phosphorus defects according to the reaction
14P4 → P′i + h°
where
KI = 1042.4 ± 2 cm?6 torr0.25[p(P4)]?0.25 exp(?1.18evkT)
. The accommodation of phosphorus interstitials is discussed in light of the crystal structure of Zn3P2.  相似文献   

10.
A search was performed for the associated production of two different Higgs bosons via a virtual Z0 in e+e? annihilation (e+e? → h10h20) using the JADE detector at PETRA. This was motivated by the interpretation of the monojet events observed at the CERN pp collider as anomalous Z0 decays into two neutral Higgs bosons (h10 and h20), where h10 is stable and escapes detection while h20 decays into hadrons. Single- or di-jet events with large momentum imbalance are then expected at PETRA energies. No evidence for such events was found in our data; this excludes h20 masses in the range of 1 to 21 GeV with 95% CL, if the branching fraction for Z0 → h10h20 is a larger than one half that for Z0 → vμvμ. The possibility that the monojets could originate from supersymmetric higgsino production from Z0 decay is also examined.  相似文献   

11.
t-channel unitarity equations are derived for n-particle overlap functions. Together with s-channel unitarity they lead to scaling laws for the inelastic s-channel partial-wave amplitudes ?l(n)(s) in the limits s → ∞, l → ∞ x = l (μ√s)3 = fixed. Assuming the validity of the scaling law in the whole range, allowed by s-channel unitarity — i.e. for l > L (s) = (α(4μ2) ? 1) (s) log (ss1) we obtain constant production cross sections σ(n)(s) at high energies s → ∞ up to s factors.  相似文献   

12.
The fundamental bands of the CF radical in the X2Π12 and X2Π32 electronic states were observed by using an infrared tunable diode laser as a source. Zeeman modulation could be used in detecting lines not only in the 2Π32 state, but also in 2Π12, because the CF radical deviates considerably from Hund's case (a). From the least-squares analysis of the observed spectra, the following molecular constants were obtained: Be = 1.416 704 (37) cm?1, αe = 0.018 419 (50) cm?1, re = 1.271 977 (17) A?, De = 6.68 (15) × 10?6cm?1, p0 = 0.008 580 (21) cm?1, p1 = 0.008 52 (11) cm?1, and ν0 = 1286.1281 (5) cm?1, with three standard errors in parentheses.  相似文献   

13.
We show that if one uses a coupled channel parametrisation for the I = 0 S-wave in processes ππ → ππ, ππ → KK? and KK? → KK? (the last deduced from a p?p → ππ + K10K10experiment) taking properly into account the analytic structure of these waves, then it is possible to fit simultaneously all cross-sections for the above processes, in the ranges 700 < s s12 < 1900 MeV for the first fit, 2MK < s12 < 1500MeV for the second, 2MK < s12 < 1170 Mev for the last. None of the three usually claimed resonances ?, S1, ?′ show up in the corresponding eigenphase analysis.  相似文献   

14.
Energies and dipole matrix elements have been calculated for He, Li, Be, B, C, N, O, F, and Ne-like ions (configurations 1s22sn12pn2?1s22sn1?12pn2+1). The Hartree-Fock energy, the correlation energy, and relativistic corrections were taken into account. Relativistic corrections were obtained by computing the entire quantity HB. Numerical results are presented for energies of the terms in the form
E=E0Z2 + ΔE1Z + ΔE2 + 1Z ΔE3 + α24 (E0pZ4 + ΔE1pZ3)
, and for the fine structure of the terms in the form
〈1s22sn12pn2LSJ|HБ|1s22sn1′2pn2′L′S′J〉=(?1)L+S′+JLSJS′L′1 × α24 (Z?A)3[E(0)(Z ? B)+Ec0]+(?1)L + S′ + JLSJS′L′2α24 (Z?A)3Ecc
. Dipole matrix elements are required for calculation of oscillator strengths or transition probabilities. For the dipole matrix elements, two terms of the expansion in 1Z have been obtained. Numerical results are presented in the form P(a, a′) = (a/Z)[1 + (τ/Z)].  相似文献   

15.
Using the re-equilibration kinetic method the chemical diffusion coefficient in nonstoichiometric chromium sesquisulfide, Cr2+yS3, has been determined as a function of temperature (1073–1373 K) and sulphur vapour pressure (10?104 Pa). It has been found that this coefficient is independent of sulphur pressure and can be described by the following empirical equation: D?Cr2+yS3=50.86 exp(-39070 cal/mole/RT) (cm2s?1). It has been shown that the mobility of the point defects inCr2+yS3 is independent of their concentration and that the self-diffusion coefficient of chromium in this sulfide has the following function of temperature and sulphur pressure: DCr=2.706×102P?14.85S2exp(-56070 cal/mole/RT). (cm2s?1).  相似文献   

16.
An ab initio SCF and CI treatment of the electronic spectrum of ammonia in both the pyramidal and planar conformation is reported which employs an [8, 6, 14, 1] AO basis of near Hartree-Fock quality; the ground state CI energy obtained for the equilibrium conformation is ?56.4241 a.u. In addition, further calculations have been carried out at the SCF level to study various photodissociation reactions of NH3. The calculated CI transition energies are seen to agree with corresponding experimental values to within 0.0–0.3 eV, usually in the 0.1-eV range. Photodissociation to the NH2 (2B?1) + H(2S) products is confirmed thereby to proceed via the A? 1a″2 → 3s state of ammonia, but contrary to earlier speculation it is found that the transformation between reactant and products is already satisfactorily described at the SCF or orbital level, i.e., a Rydberg 3s of NH3 is seen to be gradually converted into a pure hydrogenic 1s species as dissociation proceeds. In addition the photolysis of NH3 to NH2(2A1) + H(2S) is argued to occur via the C? 1a″2 → 3pz 1A′1 state and as such is seen to be a symmetry allowed process, in contrast to the previous assignment involving the B? 1a″2 → 3px, y 1E″ species. Finally an attempt is made to analyze the mechanisms of various NH + H2 photodissociation processes with the help of SCF calculations and symmetry arguments for various higher-lying excited states of ammonia.  相似文献   

17.
The emission spectrum of the He2 molecule has been rephotographed in the ~4000–~5700 Å region and the 4d(3Σu+, 3Πu, 3Δu) → 2pπ3Πg, 4d(1Σu+, 1Πu, 1Δu) → 2pπ1Πg, 4s3Σu+ → 2pπ3Πg and 4s1Σu+ → 2pπ1Πg transitions analyzed. The 4dδj3Δu, 4dπj3Πu, 4dσj3Σu+ and 4sh3Σu+ states have been characterized through v = 2 and the 4dδJ1Δu, 4dπJ1Πu, 4dσJ1Σu+, and 4sH1Σu+ states for v = 0. The term levels for these perturbed and l-uncoupled states have been confirmed (a) by analyses of bands with common levels from Δv = 0, ±1 sequences and (b) by analyses of the transitions between the above states from 4d and 4s and the c3Σg+ and C1Σg+ states associated with 3. Molecular constants are reported which have been partially corrected for the effects of l-uncoupling and the homogeneous perturbations between the state pairs J, H and j, h.  相似文献   

18.
The electronic absorption spectrum of cyanogen chloride has been investigated in the range 2200-1250 Å. The first s-Rydberg transitions, X?1Σ+3Π1 and X?1Σ+1Π1 have been assigned, and analyzed to yield exchange and spin-orbit coupling parameters. The relative intensities of these two transitions have been shown to accord with an intermediate coupling situation. The π → π1 intravalence excitations, leading to 1.3?, Δ and Σ+) states, have been discussed. It has been shown that one or both of the 1Σ? and 1Δ states have bent geometries and that the 1Σ+ state is located (tentatively) at 79 755 cm?1. Two σ → π1π → σ1 states have been assigned, one at 56 340 cm?1, the other at 74 450 cm?1. The latter assignment is tentative, being largely based on observed vibronic interferences between the X?1Σ+1Π1 transition and the 74 450 cm?1 transition. A considerable amount of vibrational oscillator strength and quantum defect data is presented.  相似文献   

19.
The non-selective nature of the (α, nγ) reaction has been used to complement information from charged-particle reactions on the level structure of 88Y and 90Y. The γ-ray spectra were recorded with a 25 cm3 Ge(Li) detector at 90° to the beam using primarily targets of 85Rb2CO3 and 87Rb2CO3 and α-particle energies of 11.8, 12.2 and 13.0 MeV. The resulting transitions were accommodated in level schemes that involved primarily the following shell model configurations: p12)1g92)?1, g92)?1g92)1, p12)1p12)?1, f52)?1g92)?1 in 88Y and p12)1d52)1, πg(92)1d52)1,p12)1s12))1 in 90Y.  相似文献   

20.
Dependence of static dielectric susceptibility and correlation length of charge density waves (CDW) with weak defects on parameter of incommensurability with lattice is investigated. In almost commensurate phase (h?hchc), χ ~ (h?hc)13 In-43 hc/h?hc and Rc ~ (h ? hc)23. In13 hc/h ? hc. Far from commensurability (h?hc) χ~ (a+h2c/h2)-23, Rc ~ (a + h2c/h2)-23, where a is the dimensionless ratio of random potential intensities, corresponding to backward and forward scattering impurities.  相似文献   

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