## SEARCH

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- Central Research Institute for Physics 66 (%)
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#### Author

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- Ghatak, K. P. 12 (%)
- Kapuy, E. 11 (%)
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## CURRENTLY DISPLAYING:

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## Strange Particle Production from SIS up to 40 A·GeV

### Acta Physica Hungarica (2005-10-01) 24: 145-156 , October 01, 2005

### Summary

<p>A review of strange particle production in heavy ion collisions at incident energies from SIS up to 40 <i>A</i>·GeV is presented. A statistical model assuming chemical equilibrium and local strangeness conservation (i.e. strangeness conservation per collision) describes most of the observed features.</p> <p>It is demonstrated that the K^{-} production at SIS energies occurs predominantly via strangeness exchange and that this channel is approaching chemical equilibrium. The observed maximum in the K^{+}/π^{+} excitation function is also seen in the ratio of strange to non-strange particle production. The appearance of this maximum around 30 <i>A</i>·GeV is due to the energy dependence of the chemical freeze-out parameters temperature <i>T</i> and baryo-chemical potential μ_{B}.

## Dose distribution, integral dose and radiation risk in computerized tomography of the skull

### Acta Physica Hungarica (1986-03-01) 59: 99-102 , March 01, 1986

The dose distribution and the integral dose for CT-examinations of the skull can be obtained experimentally from a three-dimensional array of TL-dosimeters in a tissue-equivalent phantom. In this paper we propose a new method which is based on two measured dose profiles for a single scan: f(z) along the central body axis z, and f(x,y) in the x-y plane perpendicular to z and parallel to the single phantom slices. Both dose profiles were measured with Harshaw TLD 100 rods and ribbons in an Alderson phantom in supine position. The computer — aided superposition of both dose profiles allows us then to reconstruct the spatial dose distribution and to compute the integral dose for any combination of scans. The application of this method is illustrated for a standard brain examination consisting of 14 scans adjacent to each other with a FWHM of the beam profile of 9 mm. The validity of this procedure was checked by comparing the theoretical reconstruction with TL-measurements revealing excellent agreement between calculation and experiment.

## Neutron stars in the early Universe

### Acta Physica Hungarica (1987-06-01) 61: 375-377 , June 01, 1987

## Hydrodynamics of rehadronization

### Acta Physica Hungarica (1988-09-01) 64: 111-122 , September 01, 1988

It has been shown that strange and non-strange quarks generally possess different hadronization rates in a quark-nucleon phase transition. Since the main process driving the rehadronization is the expansion and cooling of the fireball of quarks, this complicated phase transition is intimately connected with relativistic hydrodynamics. Here the consistent hydro+thermodynamical description of the transition is presented.

## Fine and hyperfine structure in thea 3II state of CH+

### Acta Physica Hungarica (1990-03-01) 67: 47-66 , March 01, 1990

Spectroscopic and theoretical studies concerning the*a*^{3}II state of CH^{+} are reviewed, with particular consideration given to the infrared predissociation spectrum of the ion. This spectrum is primarily due to vibration-rotation transitions of the*a*^{3}II state involving*v*=5 to 12 and*J*=20 to 35. Some results of a spectral simulation, making use of a rotationally-adiabatic model, are presented to justify the proposed assignment. The nuclear-hyperfine structure of the observed transitions is studied in detail, with a new calculation of splittings presented. Some semi-quantitative conclusions can be drawn with reference to the variation of the Fermi Contact parameter,*b*, as a function of internuclear distance.

## Semiempirical determination of electronic-vibro-rotational radiative transition probabilities in diatomic molecules I. Theory

### Acta Physica Hungarica (1990-03-01) 67: 3-26 , March 01, 1990

The theory of electronic-vibro-rotational radiative transitions is considered within the framework of the perturbation theory. For the case of regular (monotonic) perturbations caused by relatively far lying terms of the molecule the simple analytical expressions for the line strengths of the^{2s+1}A′→^{2s+1}A″ transitions are derived in the second order of the perturbation theory. Most distributed schemes of angular momenta coupling — Hund’s cases “a” and “b” — are considered. It is shown that the line strengths can be expressed in terms of a finite number (usually small) of the parameters (certain combinations of matrix elements describing the effects of perturbations and vibration-rotation interaction) which may be determined either from the experimental data in a semiempirical approach or from numerical calculations of adiabatic electronic and vibrational wave functions.

## AB initio method for treatment of spatially extended systems I vanishing atomic two-electron integrals

### Acta Physica Hungarica (1989-03-01) 65: 85-92 , March 01, 1989

The possibility of the calculation of molecular properties on ab initio level for extended systems is investigated in a series of papers.

In the first Part the effect of the magnitude of basis function exponents as well as that of the threshold on the number of vanishing two-electron integrals is studied.

## Harmonic analysis of NmF2 over Chungli, a subtropical location

### Acta Physica Hungarica (1994-06-01) 74: 269-278 , June 01, 1994

An empirical model based on a harmonic analysis approach for calculating the peak density of ionospheric F layer over Chungli (24.95° N, 121.23° E) for all levels of solar activity is proposed. The harmonic coefficients were obtained by normalizing the NmF2 data collected during the period 1976 to 1983 to a common level of solar activity. The coefficients exhibit expected seasonal variations. A set of 49 coefficients comprising the mean, first, second and third harmonics was found to be sufficient to recreate monthly mean NmF2 under any level of solar activity. The proposed model requires only the precalculated set of coefficients as input and enables one to use the NmF2 values so calculated as single station input to IRI or other similar models.

## Entropy in the universe

### Acta Physica Hungarica (1987-10-01) 62: 139-154 , October 01, 1987

The relic microwave radiation indicates that the universe was in the state of thermal equilibrium (heat death) in the past. The question arises how could it happen that the universe departed from the thermal equilibrium? According to the models presented here this was the outcome of an interplay among dynamic instability, matter differentiation and weakening of some interactions.