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1

All-Experimental Values of Self-Quenching Cross-Sections for nf States (n = 5-8) of Potassium Atoms

100%

GŁódŹ M., Huzandrov A., Sydoryk I., Szonert J., Klavins J.

Acta Physica Polonica A

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2007

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vol. 112

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issue 6

1185-1194

EN

All-experimental self-quenching cross-sections σ_ nf ^q are reported for K(nf) states (n=5, 6, 7, 8). The experiment was performed at varied temperatures of K vapour in a spectral cell. Time-resolved fluorescence was observed following pulsed step-wise excitation with dipole and quadrupole transitions K(4s)࢐ K(4p)࢐ K(nf). The values: σ _ 5f ^q=2.4±1.7, σ_ 6f ^q=4.5±1.4, σ_ 7f ^q=8.1±1.8, and σ_ 8f ^q=18.2±3.0 (in units of 10^ -13 cm^ -1 ) were obtained from Stern-Volmer-type plots.

2

Investigation of Double Differential Cross Sections of (γ,p) Reaction for ¹²C Nuclei

100%

Karpuz N., Mavı B., Akkurt İ.

Acta Physica Polonica A

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2016

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vol. 130

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issue 1

313-315

EN

Photonuclear reaction data, is important for basic and applied research. In additional to this, double differential data is especially vital in the field of nuclear medicine. The increase in the number of patients, admitted for treatment of cancer with heavy ions, poses a serious problem in terms of the risk of secondary cancer, as a result of exposure to particles of different energy and angle values, released after the nuclear reaction. The main point here is the possibility of damaging organs other than the treated one by the radiation generated in the reactions during the heavy ion therapy. Based on this, in order to assess the risk of secondary cancer the investigations of the double differential cross sections of reaction are required. Double differential cross sections of (γ,p) photonuclear reaction for ¹²C nuclei were calculated as functions of incoming photon energy and angle. Nuclear reaction simulation program TALYS 1.2 was used in the calculations. The calculated cross sections were compared with both the experimental cross sections and the evaluated cross sections available in literature.

3

Photoionization of He - a Field Theoretic Approach

100%

Bhattacharyya S., Mitra S.

Acta Physica Polonica A

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2001

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vol. 100

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issue 4

505-516

EN

The present paper deals with the field theoretic study of single ionization cross-sectionsσ_{ph} and σ_C of helium due to photoelectric effect and the Compton scattering, respectively, by photons of energy lying between 0-12 keV. In this energy range,σ_{ph} gradually decreases with energy whileσ_C gradually increases. There is a crossover point around 6.5 keV where σ_{ph}=σ_C=10^{-24} cm^2. Near about this crossover point σ_{ph} andσ_C curves are like mirror images. The ratio σ_C/σ_{ph} lies between 0.3 to 1.5 in the energy range under consideration. The present results are compared with existing theoretical results.

4

On the Extinction Paradox

80%

Żakowicz W.

Acta Physica Polonica A

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2002

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vol. 101

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issue 3

369-385

EN

The extinction paradox, the difference of classical and quantum scattering cross-sections for the scattering of particles by a rigid sphere (σ^Q=2π a^2=2σ^C for ka ≫ 1), is analyzed in a simpler 2D model of a rigid cylindrical potential. Rigorous solutions of the Schrödinger equation for particle beams, including also finite width beams, are derived and employed in the description of the scattering process. The scattering particle fluxes, with a thorough treatment of the forward directions, are being studied. It is pointed out that for wide beams (w ≫ a) the scattered flux can reach the value determined by the quantum theory, provided that it is measured at distances R ≫ waλ. Moderately narrow beams (1≪ w≪ a) behave as classical trajectories, and their scattering can be described in classical terms. Thus, the classical limit of quantum scattering requires not only that the de Broglie wavelength λ_B is much smaller than the size of the scatterer (a ≫ λ_B), but also that the transverse width of beams of de Broglie's waves is small, w≪ a.

5

X-Ray Magnetic Circular Dichroism and Compton Scattering: Application to 5f Electron Systems

80%

Kernavanois N., Sanchez J., Dalmas de Réotier P., Yaouanc A.

Acta Physica Polonica A

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2001

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vol. 100

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issue 5

629-645

EN

The basic properties of magnetism depend strongly on the spin and orbital components of magnetization. Information about the magnetic moments can be gained using new techniques, like X-ray magnetic circular dichroism or Compton scattering, developed at third-generation synchrotron sources. After a brief introduction to the basic principles of these new magnetic tools, examples of experiments on 5f-electron based systems are presented.

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All-Experimental Values of Self-Quenching Cross-Sections for nf States (n = 5-8) of Potassium Atoms

Investigation of Double Differential Cross Sections of (γ,p) Reaction for ¹²C Nuclei

Photoionization of He - a Field Theoretic Approach

On the Extinction Paradox

X-Ray Magnetic Circular Dichroism and Compton Scattering: Application to 5f Electron Systems