Experimental determination of the size of a source from spectral measurements

We show how spectral changes measurements in a Young interferometer can be used to determine the dimension of an incoherent source. The experimental results confirm the theoretical predictions.     

Proton size anomaly

A measurement of the Lamb shift in muonic hydrogen yields a charge radius of the proton that is smaller than the CODATA value by about 5 standard deviations. We explore the possibility that new scalar, pseudoscalar, vector, and tensor flavor-conserving nonuniversal interactions may be responsible for the discrepancy. We consider exotic particles that, among leptons, couple preferentially to muons and mediate an attractive nucleon-muon interaction. We find that the many constraints from low energy data disfavor new spin-0, spin-1, and spin-2 particles as an explanation.     

Proton alignment in 82Sr investigated by g-factor measurements

The proton alignment in 82Sr has been investigated by the g-factor measurements of the ground state rotational band levels up to spin I = 8+. The g-factors were measured by a transient-magnetic-field ion implantation perturbed angular distribution method. The obtained g-factors increase with the increasing of spin along the band and clearly show the g9/2 proton alignment that starts at I = 6+.     

Determination of the X-pinch-based X-ray source size

It is shown that an X-ray source 0.5–2 μm in size for the spectral region above 3 keV can be implemented based on a compact pulse generator with an impedance of 0.13Ω using an X-pinch made of four molybdenum wires. The technique for determining the source sizes and the results of the experimental determination of the X-pinch emitting region sizes are presented. The parameters of the X-pinch consisting of wires of different diameters are optimized for this generator to fabricate an X-ray source of minimum sizes.     

Proton capture reaction of ³³S in nova V1065 Centauri

Previous studies have shown that 33 S(p, γ) 34 Cl is the most important reaction that affects the abundance of 33 S in the product of nova nucleosynthesis. In this paper, a more accurate thermonuclear reaction rate of 33 S(p, γ) 34 Cl in the nova is calculated based on the newly measured 34 Cl nuclear resonance levels. The electron screening correction and the non-resonance and narrow-resonance contributions are considered. The calculations are also combined with the recent observational data of nova V1065 Centauri and show that the thermonuclear reaction rates of 33 S(p, γ) 34 Cl are significantly different in the improved method. Because these results can affect the isotopic ratio of sulfur in the nova ejecta significantly, we make an estimate of the values of 32 S/ 33 S and 33 S/ 33 S ⊙ , which can be used as a diagnostic tool for the novae.     

Proton relaxation measurements on lipid membranes oriented at the magic angle

Smectic lipid-water systems were macroscopically oriented between glass slides. Lipids used were dimyristoyllecithin, potassium oleate, and potassium linolate. Proton spectra of hitherto unattained resolution were observed when these lipid model membranes were oriented at the magic angle. The T₁ value of resolved resonances was measured as a function of temperature at 100 and 360 MHz. The residual linewidth at the magic angle orientation is determined by the inherent anisotropy of diamagnetic susceptibility in lipid bilayers. The T₂ value of the methylene resonance in the potassium oleate-water system was evaluated from a saturation study. The conclusion from these experiments is that the model membrane is a two-dimensional fluid; the molecular motion is a plane perpendicular to the bilayer normal is characterized by a single correlation time of the order of 10⁻¹⁰ sec. Dimyristoyllecithin was also investigated in vesicle form; T, values and activation energies differ from the multilayer results but most of the discrepancy can be ascribed to the different water contents of the two systems.     

Proton NMR and susceptibility measurements on the magnetic core of ferritin

We report an investigation of the magnetic core of the biomolecule ferritin by means of proton nuclear magnetic resonance (NMR) and relaxation, magnetic susceptibility and scanning electron microscope (SEM) measurements. SEM images show that the outer protein shell is taken out completely by an appropriate chemical treatment and indicate particle sizes ranging from 10² to 10⁴ nm. Susceptibility measurements show a maximum in the zero-field-cooled data which is strongly field-dependent and can be ascribed to superparamagnetic behavior, whereas the hysteresis curve is different from normal ferritin. Proton NMR and spin-lattice relaxation data as a function of temperature at 4.7 T suggest the presence of an antiferromagnetic transition around 100 K.     

Proton distortion and asymmetries in the (p, π) reaction

Recent experiments on the ($\text{p}\text{, π}{}^{\mathrm{+}}$) reaction in light nuclei at 200 MeV proton kinetic energy show a striking uniformity in the asymmetry for varying targets and final nuclear states. We find that this qualitative feature can be explained by conventional proton distortion, with both absorptive and spin-orbit parts, using a single-nucleon mechanism and reasonable neutron bound states. The results are rather sensitive to the distorting and binding potentials. Aspects of pion distortion are also considered, as is the possible role of proper orthogonality for the nucleon states.     

Proton alignment in 82Sr investigated by g-factor measurements

The proton alignment in ⁸²Sr has been investigated by the g-factor measurements of the ground state rotational band levels up to spin I=8⁺. The g-factors were measured by a transient-magnetic-field ion implantation perturbed angular distribution method. The obtained g-factors increase with the increasing of spin along the band and clearly show the g_9/2 proton alignment that starts at I=6⁺.     

Twist and finite size effects for the source method

We analyze the finite size effects for the source method in pure lattice gauge theory at weak coupling. They are found to be strongly suppressed by twisting the boundary conditions, forSU(3) by typically an order of magnitude.     

On determining the spot size for laser fluence measurements

Energy fluence, defined as pulse energy over irradiated area, is a key parameter of pulsed laser processing. Nevertheless, most of the authors using this term routinely do not realize the problems related to the accurate measurement of the spot size. In the present paper we are aiming to approach this problem by ablating crystalline Si wafers with pulses of a commercial KrF excimer laser (λ = 248 nm, τ = 15 ns) both in vacuum and at ambient atmosphere. For any pulse energy, the size of the ablated area monotonously increases with increasing number of pulses. The difference in the ablated area could be as high as a factor of three when 2000 consecutive pulses impinge on the surface. The existence and extent of the gradual lowering of multi-pulse ablation threshold queries the applicability of routinely used procedure of dividing the pulse energy with the size of the ablated area exposed into either carbon-paper or a piece of Si with one or a few pulses when determining the fluence. A more quantitative way is proposed allowing comparison of results originating from different laboratories.     

Proton µ‐PIXE mapping,AFM imaging and size statistics of mineral granules in a dental composite

We applied proton microbeam particle‐induced X‐ray emission (µ‐PIXE) for mapping Ca, Zr, Ba and Yb, and atomic force microscopy (AFM) for imaging the surface landscape of a dental composite which releases Ca²⁺ and F^? for the protection of hard dental tissues. Three areas ～250 × 250 µm² located ～0.5–2 mm apart on a smooth surface specimen were mapped with 3.1 MeV protons focused to a ～3.0 µm spot and at ～3.9 µm pixel size sampling. The maps evidenced particles with diameters of 3.2–32 µm (Ca), 20–60 µm (Zr), ≤ 4 µm (Ba) and 10–50 µm (Yb). Cross‐section area histograms of Ca‐rich particles fitted with 2–6 Poisson functions revealed a polydisperse size distribution and substantial differences from an area to another, possibly implying large local variations of Ca²⁺ released in the hard tissue near a dental filling of a few millimeters in diameter. Such imbalances may lead to low local Ca²⁺ protection of the dental tissue, favoring the onset of secondary caries. Similarly, AFM images showed high zone‐dependent differences in the distributions of grains with apparent diameters of 1–4 µm, plausibly recognized as Ca‐ and Ba‐containing particles. In a simple model based on demineralization data, lateral diffusion of Ca²⁺ between adjacent domains containing high‐ and low‐area Ca‐rich grains is described by exponential concentration gradients. These gradients may generate appreciable electromotive forces, which may enhance electrochemically the local tissue demineralization. Similar effects are to be expected in the protective action of F^? ions released from microgranules of YbF₃ and of Ba fluoroaluminosilicate glass. Copyright © 2010 John Wiley & Sons, Ltd.     

Defining a reaction plane in particle-fission correlation measurements

A simple model is developed to describe the spin misalignment in particle-fission correlation measurements. Analytical expressions are derived for the spin fluctuations as a function of fission fragment emission angle. Some recent experimental results onα-fission correlations are interpreted within the framework of the model.     

光源线度对相关检测的影响

讨论了空间非相干源及相干源的线度对相关检测的影响,包括归化峰值强度,绝对峰值强度及相关轮廓,以环形物为例对圆光源进行了数值计算.数值计算和实验表明,相干相关时光源线度应与制作空间滤波器时相同或相近,而非相干源线度则可显著超过归化峰值强度半功率点的容许值,以大大提高峰值强度而不使相关轮廓明显劣化.     

Far field measurement of optodynamic source size

A micro-explosion occurring after pulsed laser-induced breakdown in water can be effectively described as an optodynamic phenomenon. It is a source of shock waves that propagate into the surrounding medium. We present a measurement of the source size based on far field detection of the propagating waves using a beam deflection probe technique. By taking into consideration the moving breakdown model the relation between the size of the breakdown region and the apparent size of the optodynamic source is shown. An energy dependent enlargement parameter d is introduced which describes the relation. PACS 42.62.-b; 52.50.Jm; 52.35.Dm     

Investigation of sample size effects in impedance tube measurements

A series of careful impedance tube measurements using different sizes of glass fibre and felt samples have demonstrated that frame resonance effects result from slightly oversize samples. The appropriate size of a sample is investigated while also avoiding air leakage. Diameters of 0.5 or 1.0 mm less than the inner diameter of the tube are found to avoid these effects.     

Velocity measurements in jets with application to noise source modeling

This paper describes an experimental investigation of the statistical properties of turbulent velocity fluctuations in an axisymmetric jet. The focus is on those properties that are relevant to the prediction of noise. Measurements are performed using two single hot-wire anemometers as well as a two-component anemometer. Two-point cross correlations of the axial velocity fluctuations and of the fluctuations in the square of the axial velocity fluctuations are presented. Several reference locations in the jet are used including points on the jet lip and centerline. The scales of the turbulence and the convection velocity are determined, both in an overall sense as well as a function of frequency. The relationship between the second and fourth order correlations is developed and compared with the experimental data. The implications of the use of dimensional as well as non-dimensional correlations are considered. Finally, a comparison is made between the length scales deduced from the flow measurements and a RANS CFD calculation.     

Direct measurements of auroral kilometric radiation in a limited source

The enhancement of auroral kilometric radiation near its lowest frequency has been detected in the polar edge of the auroral zone in the POLRAD experiment with the INTERBALL-2 satellite. The difference between the local electron cyclotron frequency and the lowest frequency of enhanced radiation is 8–20 kHz, indicating the closeness to the source of auroral kilometric radiation. According to the detailed analysis of low-frequency auroral kilometric radiation, its amplitude is larger than the “background” values by a factor of 20–70 and has amplitude modulation with characteristic periods of 40-60 s. The increase in the intensity at low frequencies is attributed to the intersection of the source region by the satellite and the detection of waveguide modes in it.     

Proton reaction cross sections as measures of the spatial distibutions of neutrons in exotic nuclei

Proton and neutron densities from Skyrme-Hartree-Fock calculations of a number of nuclei with masses ranging from 28 to 58 have been used to generate optical potentials for proton elastic scattering. Those potentials, generated by folding the structure functions with effective in-medium nucleon-nucleon (NN) interactions, have been used to evaluate proton total reaction cross sections; cross sections that reveal signatures of the structures.     

A simple impulse sound source for measurements in room acoustics

This paper deals with the construction and characteristics of a specially designed wooden clapper intended to operate as an impulse sound source for measurements in rooms. It is to be used as an alternative impulse sound source for experimental estimations of impulse responses of rooms located at remote and specific places where none of the standard sound sources - an omnidirectional loudspeaker system, etc. - can be used. The paper describes the spectral characteristics and directivity of the clapper impulse. Its features are compared with other impulse sources.