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1

Alfa, beta, gamma. Jak odkrywano i badano promieniotwórczość naturalną

Goworek T.

Postępy Fizyki

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2017

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T. 68, z. 2

42--64

PL

Artykuł przedstawia zarys historii badań nad promieniotwórczością naturalną, od pierwszych obserwacji Niepce de Saint Victora w r. 1851 do odkrycia jądra atomowego przez Rutherforda w r. 1911.

2

Positrons in naphthalene : critical remarks on the relation between o-Ps lifetime and void size

Goworek T., Zgardzińska B., Wawryszczuk J.

Nukleonika

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2013

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Vol. 58, No. 1

183-187

EN

Lowering the temperature or applying high pressure leads to elimination of positronium component in the e+ lifetime spectrum in solid naphthalene. Disappearance of positronium means reaching the free volume size limit at which there is no energy level in the potential well. It allows to estimate that size, which is found inconsistent with predictions of the popular Tao-Eldrup model. The range of applicability of that model is discussed. The dependence of the free e+ decay constant on pressure indicates that positronium is formed not only in the blob processes, but during the whole free positron life. The lifetime of free positrons begins to rise with temperature earlier than Ps intensity.

3

Positron study of the structure of nonadecane-tricosane mixed solid

Zgardzińska B., Goworek T.

Nukleonika

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2010

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Vol. 55, No. 1

47-49

EN

Positron annihilation lifetime and intensity were measured as a function of temperature for a binary mixture of two normal alkanes. The rotator phase is preceded by the range of about 7 K, in which one observes instability of spectrum parameters. In that range the mixed solid, being initially introduced into rotator phase, transforms to a rigid one in the time scale of several hours.

4

Pore size determination by positron annihilation lifetime spectroscopy

Jasińska B., Dawidowicz A. L., Goworek T., Wawryszczuk J.

Optica Applicata

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2003

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Vol. 33, nr 1

7-12

EN

Two Vycor glasses were investigated using PALS method. The model of pick-off annihilation in cylindrical free volume was applied to evaluate the pore radii. The o-Ps mean lifetime value in the pores changed from 6.5 to 40 ns in one glass, while from 13 to 51 ns in the other (softer) one. The determined pore radii, using a cylindrical shape model, were from 0.5 to 1.4 nm and from 0.7 to 1.6 nm, respectively.