Range,light-cone dominance and scaling at low Q2 in electroproduction

The analysis of light cone singularities is used to connect the y · P, or range, dependence of the current correlation function with the Q² dependence of the inelastic electroproduction structure functions. We study for what regions of the Q², ν plane and for what y · P dependence the leading light-cone singularity dominates contributions from less singular terms with the same y · P dependence. When the leading singularity can be shown to dominate for a particular region of Q² and ν, we study whether this implies scaling for νW₂ in that kinematic region. It is shown that a division of the current correlation function into short and long range contributions is fundamentally ambiguous and not related to scaling at low Q². Short range terms which are shown to be light-cone dominated for all Q² so long as ν → ∞, are found but are shown not to scale at low Q² and to be indistinguishable from corrections to long range terms which produce the leading Regge behavior. We show that leading Regge terms may receive contributions far away from the light cone for small virtual photon mass, but that light-cone dominance and scaling are recovered when the photon mass is taken very large.     

Rapidity correlations in π+ p,K + p andpp interactions at 250 GeV/c

Two- and three-particle rapidity correlations are analyzed inK ⁺ p and π⁺ p-interactions at 250 GeV/c. The main contribution to the two- and three-particle correlation functions comes from mixing of events of different multiplicity. The (short range) two-particle correlation remaining after exclusion of mixing is significantly larger for (+?) than for the equal charge combinations, and is positive for a wider range in rapidity difference. FRITIOF and a 2-string DPM are excluded by our data. A quark-gluon (multi-)string model can describe our inclusive correlation function, but needs to be tuned on the short range part. The multiplicity mixing part increases much faster with increasing energy than the short range part. In the central region, our correlation is similar to that observed ine ⁺ e ^? and μp collisions at similar energy.     

Thermonuclear reaction rates for proton induced reactions on 41K and neutron induced reactions on 41Ca

The yield of γ-rays from the reaction ⁴¹K(p, γ)⁴²Ca has been measured as a function of bombarding energy over the range 0.68–2.48 MeV and from the reaction ⁴¹K(p, αγ)³⁸Ar over the range 1.20–2.48 MeV, and the yield of neutrons from the reaction ⁴¹K(p, n)⁴¹Ca has been measured from threshold to a bombarding energy of 2.48 MeV. The energy dependence of the cross sections is compared with statistical-model calculations with global optical-model parameters in all particle channels. The calculations seriously overestimate the cross section for the neutron channel and underestimate those for the other channels. A reduction in the imaginary well depth in the neutron channel leads to good agreement with all the data. Statistical-model calculations with this modified set of parameters are then carried out to provide cross sections for the astrophysically interesting reactions ⁴¹Ca(n, p)⁴¹K, ⁴¹Ca(n, α)³⁸Ar, and ⁴¹Ca(n, γ)⁴²Ca. Thermonuclear reaction rates are calculated for all six reactions over the temperature range 5 × 10⁸–10¹⁰K which includes the range of temperatures of interest in nucleosynthesis calculations.     

Rotational analysis of vibrational polyads in tetrahedral molecules: Line parameters of the infrared spectrum of 12CH4 in the range 2250–3260 cm−1—Theory versus experiment

Experimental and theoretical line parameters of the infrared spectrum of ¹²CH₄ in the range 2250–3260 cm^?1 covering the pentad ν₁, ν₃, 2ν₂, ν₂+ν₄, and 2ν₄ are reported. The individual line strengths are reproduced with a relative precision of 12% comparable to the experimental accuracy. In all, 6499 transitions have been calculated in the spectral region 2250–3260 cm^?1. Their intensities range from 2.5 to 213 000 × 10^?24 cm/molecule. Virtually all the absorptions of ¹²CH₄ in this range are satisfactorily reproduced.     

The 42Ca(α, γ)46Ti and 42Ca(α, p)45Sc cross sections and the mass-45 bottleneck

The yield of γ-rays from the reaction ⁴²Ca(α, γ)⁴⁶Ti has been measured as a function of bombarding energy over the range E_α = 3.42–5.62 MeV and from ⁴²Ca(α, pγ)⁴⁵Sc over the range E_α = 4.06–5.92 MeV, and the yield of protons from the reaction ⁴²Ca(α, p)⁴⁵Sc has been measured over the range E_α = 4.78–5.92 MeV. Cross sections for all three reactions have been extracted from the data and compared with global statistical-model calculations. The agreement is good. Thermonuclear reaction rates under stellar conditions appropriate for silicon burning are calculated and their significance for the approach to and bridging of the mass-45 bottleneck in the upward flow of nucleosynthesis is discussed.     

Electronic spectra of XeNe molecules in the range 77100-90100 cm-1 near Xe* (6p, 5d, 6p’, 7s, 7p, 6d) obtained by the (3 + 1) REMPI and (2 + 1) REMPI methods

The electronic spectra of XeNe molecules in the range of 77100-90100 cm^-1 are measured by the method of laser resonance multiphoton ionization in a supersonic jet. The photoionization spectra are obtained upon two- and three-photon excitations of molecules and their ionization by the next photon. In the range of 80300-90100 cm^-1 near Xe*(5d, 6p’, 6d, 7s, and 7p), the spectra are obtained for the first time. A whole number of vibrational systems are measured in this range. The majority of vibrational systems near Xe* (5d, 6d, 7p, and 7s) are located in the red range with respect to their dissociation limits. In the blue range with respect to the dissociation limits, continua corresponding to transitions of molecules from the ground state to repulsive potential curves of excited states are detected. For a number of excited states of XeNe molecules, the vibrational analysis is performed and molecular constants are estimated.     

Dielectronic recombination rate coefficients for Fe23+ ion

The dielectronic recombination rate coefficients are explicitly calculated for the Li-like ion Fe²³⁺, which recombines with the continuum electron to form Fe²²⁺. Both 1s²2s and 1s²2p initial states are treated for the temperature range 1～8 keV. The rate coefficients are obtained from a direct evaluation of the Auger and radiative transition probabilities which are calculated from nonrelativistic Hartree-Fock wave functions. The L-shell electron excitation with Δn≠0 is found to be the dominant transition, while the 2s→2p excitation with Δn = 0 contributes approx. 10–25% of the Δn≠0 value. The K-shell excitation effect is about 1～30% in the temperature range considered, and the cascade effect is estimated to be a reduction in the rate of about 14%.     

Kurzlebige Compoundzustände in der niederenergetischen Elektron-Helium-Streuung

Electron scattering measurements have been made of the energy dependences of the excitation of the Helium 2³ S, 2¹ S, 2³ p, and 2¹ P states at different scattering angles in the range from 20 to 145°. In the energy range from 22 to 23 eV five overlapping resonances of the (e-He)-system have been determined, one of which (22.42 eV) is identified to be a 3² S, another (22.60 eV) a 3² P-state. The energy values of the other resonances are resp. 22.55, 22.75, and 22.85 eV. The half-widths are below approximately 40 meV. In the 2³ P-channel three peaks vanish at the same scattering angle, a fact, which seems not understandable in terms of first order resonance poles.     

Interactions of μAl acceptor impurity in weakly and heavily doped silicon

The interactions of the aluminum acceptor impurity in silicon are investigated using polarized negative muons. The polarization of negative muons is studied as a function of temperature on crystalline silicon samples with phosphorus (1.6×10¹³ cm^?3) and boron (4.1×10¹⁸ cm^?3) impurities. The measurements are performed in a magnetic field of 4.1 kG perpendicular to the muon spin, in the temperature range from 4 to 300 K. The experimental results show that, in phosphorus-doped n-type silicon, an _μAl acceptor center is ionized in the temperature range T>50 K. For boron-doped silicon, the temperature dependence of the shift of the muon spin precession frequency is found to deviate from the 1/T Curie law in the temperature range T ? 50 K. The interactions of a _μAl acceptor that may be responsible for the effects observed in the experiment are analyzed.     

Measurement of radiation energy by spectrometric systems based on uncooled silicon detectors

The results of measurements of radiation energy for single-channel detection systems based on uncooled silicon planar detectors and spectrometric readout electronics, developed at the Kharkiv Institute of Physics and Technology National Scientific Center, are presented. Radiation sources of ⁵⁵Fe, ²⁴¹Am, ⁵⁷Co, ¹³⁷Cs, and ^99MTc and characteristic X-ray radiation (CXR) are used in the experiments. The radiation energy in the range of E _γ = 3–140 keV is measured by a spectrometer based on a Si PIN detector. The energy resolution (full width at half maximum, FWHM) in this energy range changes with increasing photon energy from 0.97 to 1.3 keV. The CXR of calcium (K _α = 3.69 keV) is measured by a Si planar detector with an input aluminum foil. Emission lines in the energy range of E _γ = 0.04–0.662 MeV are measured by a CsI(Tl) scintillator-silicon PIN-photodiode detection system. The energy resolution of the spectrometer changes with quantum energy increasing from 22 to 70 keV. The CXR from cesium and iodine with K _α 31 and 28.6 keV, respectively, is recorded.     

The vertex constant for the virtual decay of a nucleus into two charged particles within the effective range theory

Explicit expressions for the virtual a → b + c decay vertex constant (or the asymptotic normalization factor) for charged particles b and c are obtained for the first time using the effective range function K(k ²) for the standard effective range expansion and for the case where K(k ²) has a pole. The bound and resonant states of the ²He nucleus and the resonant states of the ²He and ⁸Be nuclei are considered as physical examples. A trajectory in the complex momentum plane is constructed for the transition from the resonant state to the virtual state while the Coulomb interaction gradually decreases.     

Measurements of the neutron-proton analyzing power in the energy range from 17 to 50 MeV

Measurements of the analyzing power A_y for neutron-proton scattering in the energy range from 17 to 50 MeV are reported. These data improve considerably the precision of the np data base in this energy range. Preliminary phase-shift analyses indicate reduced uncertainties in the np ³P(T = 1) phases and in the ³D(T = 0) phase shifts.     

Electron scattering from some even fp- and N50-shell nuclei with implanting the influence of short-range correlation functions

The influence of two body short range correlations on elastic electron scattering charge form factors, charge densities as well as root mean square charge radii of some fp-shell nuclei (for example, ⁴⁸Ca, ⁵⁰Cr, ⁵⁴Fe, ⁵⁸Ni, ⁷⁰Ge and ⁷⁴Se) and some N50-shell nuclei (for example, ⁸⁸Sr and ⁹⁰Zr) is analyzed using the one- and two-body terms in the cluster expansion together with the single particle harmonic oscillator wave functions. The Jastrow-type correlation function is utilized to embed the effect of short range correlations into elastic charge form factors F(q) and charge densities ρ(r). Both F(q) and ρ(r) depend upon the harmonic oscillator parameter b and the correlation parameter β (which initiates from the Jastrow correlation function). Here, the parameters b and β are determined via the fitting to the measured charge form factors. The embedding of short range correlations imitates the measured charge form factors at the high momentum transfers (q ≥ 2 fm⁻¹). It is noticed that the implanting of short range correlations is required for obtaining a remarkable alteration in the computed elastic charge form factors which in turn leads to explain the data of electron scattering astonishingly throughout the entire range of considered momentum transfers.     

Fluorescence of Pr3+-ions in La1−xPrxP5O14

The fluorescence spectrum of La_1?xPr_xP₅O₁₄ was investigated for the range of 0.001 ? x ? 1. For small Pr³⁺-concentration the fluorescence starts almost completely from the ¹D₂ level, whereas in pure PrUP the total fluorescence arises from the energetically higher ³P₀ level. This is contrary to the usually observed concentration quenching. In the intermediate concentration range fluorescence lines from both levels are observed independent of the excitation.     

Point contact spectroscopy in Ga single crystals

The current-voltage characteristics of point contacts in Ga single crystals have been measured in the liquid helium temperature range. At least six singular structures were found in energy range between 6 to 31 mV of the spectra d²V/dI². They are in good agreement with the structure of the phonon density-of-states determined from the inelastic neutron scattering experiment by Reichardt et al. The obtained spectra were used to estimate the electron-phonon coupling parameter.     

Measured integrated band intensities and simulated line-by-line spectra for 12C2HD between 25 and 2.5 μm,and new global vibration–rotation parameters for the bending vibrations

The global analysis of published high-resolution vibration–rotation spectra of ¹²C₂HD in the bending spectral range is presented, resulting in an extension of the known vibration–rotation assignments, including a new band 2v₄+v₅←2v₄ (^IΠ←Δ). Experimental integrated band intensities are reported in the range from 25 to 2.5 μm, and both v₄ and v₅ bending fundamentals are simulated line by line. An extensive line list is produced in the bending energy range, to supply previously missing information in databases.     

Study of the absorption characteristics of molecular oxygen in the Schumann-Runge system at high temperatures: II. Experiment and comparison with calculation

Absorption cross sections of oxygen molecules in the UV spectral range are experimentally determined in the temperature range 1600–6000 K. The absorption cross sections are measured in oxygen or in its mixtures with argon behind the shock wave front. Measurements are performed for the spectral range 190–270 nm, which pertains to the electronic transition X ³Σ _g ^? → B ³Σ _u ^? of the Schumann-Runge system. The absorption cross sections are also measured at temperatures 291 and 3300 K in the range 160–185 nm. The measured absorption cross sections are compared with the calculated spectra of the O₂ molecule.     

Autoionizing and highly excited states in the spectrum of triply ionized tin Sn IV

Transitions from autoionizing states in the spectrum of Sn IV in the range 200–630 Å, occurring due to the excitation of electrons from the inner 4d ¹⁰ shell, are investigated with high resolution. The transitions from the 4d ⁹5p ², 4d ⁹5s6p, and 4d ⁹5snf (up to n = 9) configurations are identified and their autoionization widths are measured. Transitions from the highly excited 4d ¹⁰ ns (n = 8–10), 4d ¹⁰6p, and 4d ¹⁰7d configurations are also revealed and the ionization potential of Sn IV is refined. The data obtained are compared with the results of calculations by the Hartree-Fock and semiempirical methods.     

Measurement of π−p → π0π0n at 6, 8 and 12 GeV/c

All γ's and the neutron from the reaction π^?p → π⁰π⁰n are detected. The magnitude of the π⁰π⁰ S-wave and the cosine of its phase angle (relative to the known D-wave) are determined. The I = 0 amplitude, S₀, is near the unitarity limit in the range 600 to 900 MeV and again around 1200 MeV.     

Estimate of the Δ(1232) component in the 12C nucleus

The cross section for the ¹²C(γ, π⁺ p) reaction was measured in the range of the Δ(1232) isobar. The data were analyzed using the models taking into account the nucleon and isobaric degrees of freedom of the ¹²C nucleus. The conclusion is drawn that in the large-momentum transfer range the π⁺ p pairs are produced in the course of the direct knocking-out of Δ⁺⁺ isobar from the nucleus. The probability of finding the Δ isobar in the ground-state ¹²C nucleus is estimated at 0.018±0.005 Δ isobars per nucleon.