In: Computational and Mathematical Methods in Medicine, 2020, vol. 2020, p. 1–11
In this work, a method is established to calibrate a model that describes the basic dynamics of DNA damage and repair. The model can be used to extend planning for radiotherapy and hyperthermia in order to include the biological effects. In contrast to “syntactic” models (e.g., describing molecular kinetics), the model used here describes radiobiological semantics, resulting in a more...
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In: The European Physical Journal D, 2008, vol. 46, no. 1, p. 9-14
We present the first experimental study of time-resolved fluorescence from laser-excited Cs(6P1/2) atoms isolated in a solid ⁴He matrix. The results are compared to the predictions of the bubble model including the interaction of the atomic dipole with its radiation reflected at the bubble interface. Our results show that in liquid He as well as in the body-centered cubic (bcc)...
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In: Physical Review A, 2008, vol. 77, no. 12, p. 012502
We give a detailed account on our semiempirical calculations of the forbidden electric tensor polarizability α₂⁽³⁾ of the ground state of free Cs atoms and of Cs atoms implanted in a solid 4He matrix. The results are compared with measurements of α₂⁽³⁾ in the free atoms [Europhys. Lett. 76, 1074 (2006)] and in He-trapped atoms [Phys. Rev. A 75, 042505 (2007)]. Features with...
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In: Nature Physics, 2007, vol. 3, no. <, p. 786 - 789
The modification of melting temperatures and pressures by dissolved impurities is well known in classical fluids. However, to our knowledge such effects have never been studied in quantum solids because of the difficulties in introducing impurities into such crystals that exist only at cryogenic temperatures, and, in the case of ⁴He, at pressures exceeding 25 bar. Here, we present an effect...
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In: Physical Review A, 2007, vol. 76, no. 2, p. 022502
We present a systematic experimental study of the absorption and fluorescence spectra of the 6S1/2-6P1/2 transition in Cs atoms isolated in solid ⁴He matrices. The bubble model developed earlier for alkali-metal atoms in liquid He is revised and applied to the present system. The analysis of the dependencies of absorption and fluorescence wavelengths on He...
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In: Physical Review A, 2007, p. 042505
We have measured the electric tensor polarizabilities of the hyperfine levels of Cs atoms embedded in a body-centered cubic ⁴He crystal. The polarizabilities are inferred from the shift of optically detected magnetic resonance lines in each hyperfine level induced by static electric fields up to 50 kV/cm. We recorded the magnetic resonances both by scanning the rf frequency and in a...
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Thèse de doctorat : Université de Fribourg, 2006.
This thesis work describes a detailed study of the Stark interaction in the ground state of cesium atoms trapped in a solid helium matrix. The motivation for the investigation of electric field effects on alkali species implanted in solid helium is related to the original main goal of our experimental activities, i.e., the measurement of a permanent atomic electric dipole moment (EDM). The...
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In: Europhysics Letters, 2006, vol. 76, no. 6, p. 1074-1080
We present a new theoretical analysis of the strongly suppressed F- and M-dependent Stark shifts of the Cs ground-state hyperfine structure. Our treatment uses third-order perturbation theory including off-diagonal hyperfine interactions not considered in earlier treatments. A numerical evaluation of the perturbation sum using bound states up to n = 200 yields ground-state...
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In: Fizika Nizkikh Temperatur, 2006, vol. 32, no. 11, p. 1297-1319
A little more than a decade ago our team extended the field of defect spectroscopy in cryocrystals to solid ⁴He matrices, in both their body-centered cubic (bcc) and hexagonally close-packed (hcp) configurations. In this review paper we survey our pioneering activities in the field and compare our results to those obtained in the related fields of doped superfluid helium and doped helium...
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In: Physical Review A, 2006, vol. 74, p. 032504
We present experimental and theoretical studies of the absorption, emission, and photodissociation spectra of Rb₂ molecules in solid helium. We have identified 11 absorption bands of Rb₂. All laser-excited molecular states are quenched by the interaction with the He matrix. The quenching results in efficient population of a metastable (1) ³πu state, which emits...
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