[en] The absorption coefficients of the collision induced spectrum of the interaction H²-He at 300 K between 200 and 700 cm^-₁ are presented. A lack of absorption (dip) due to the intercollisional interference effect is clearly seen at the frequency of the pure rotation line S¹ of the free molecule of H²

[en] We present a general framework in which non-linear optical phenomena for an ensemble of accelerated atoms can be studied. We show the equivalence of various approaches through frame transformations. This equivalence is understood within the context of a covariant formalism which is briefly sketched. The choice of the frame, in which the atoms are not accelerated but where the light spectrum and the atomic source term are correspondingly modified, leads to the simplest calculation. It enables one to use the usual density matrix diagrams and associated rules. Explicit examples are given in the case of a sinusoidal gravitational wave. Finally a brief discussion of the signal-to-noise ratio of the sidebands induced by gravitational waves on saturation resonances is outlined

[en] After neutron activation, iridium samples have been kept at low temperature (22 K). The electrical resistivity decreases or increases with time according to whether the activation was moderate or high. A coherent interpretation is given implying the recoil-induced creation of a Frenkel pair during activation and its subsequent annihilation, with a probability approximately= 0.8, due to a second subthreshold recoil

[en] Two heavy ion interaction potentials have been computed using the same nuclear force. One has been obtained from symmetric semi-infinite nuclear matter slabs and the other one from finite nuclei. After a proximity scaling, two rather different universal functions are obtained. We argue that this is due to the different surface thickness of semi-infinite nuclear matter and finite nuclei. Consequently, it is the universal function obtained from the nucleus-nucleus systematics that should be used in the applications

[en] The first observation of the nuclear magnetic resonance of the uranium 235 is reported. It has been performed on pure liquid uranium hexafluoride at 380 K. The measured magnetogyric ratio is /γ(²³⁵U)/ = 492.6 +- 0.2 rad.s^-1G^-1

[en] When a Hamiltonian H depends on variables phisub(i), the values of these variables which minimize H satisfy the equations deltaH/deltaphisub(i) = O. If this set of equations is solved by iteration, there is no guarantee that the solution is the one which minimizes H. In the case of a harmonic system with a random potential periodic with respect to the phisub(i)'s, the fluctuations have been calculated by Efetov and Larkin by means of the iteration method. The result is wrong in the case of a strong disorder. Even in the weak disorder case, it is wrong for a one-dimensional system and for a finite system of 2 particles. It is argued that the results obtained by iteration are always wrong, and that between 2 and 4 dimensions, spin-pair correlation functions decay like powers of the distance, as found by Aharony and Pytte for another model

[en] We have extended to temperatures below 1 K the optical pumping technique for polarizing the nuclei of ground state ³He atoms in the gas phase. A superfluid ⁴He film covering the surface of the pyrex cell protected the ³He atoms from the rapid depolarization processes that would be experienced in the presence of bare pyrex walls. Relatively long relaxation times of order 10³ s were observed at temperature down to 500 mK, the lowest temperature accessible with the present apparatus

[en] The magnetic properties of NpSbTe and NpAsTe have been studied. NpSbTe remains paramagnetic down to 1.8K. NpAsTe is ferromagnetic below Tsub(c) = 25 K; the magnetization reaches 1.07μsub(B)/Np in a 40 kOe field but is not yet saturated. In the paramagnetic range, results for both compounds indicate a 3 + valence state of Np ions. In the case of NpAsTe, results are in agreement with recent crystal field calculation, Moessbauer effect and electrical resistivity measurements

[en] Fission yields of two ¹³⁶I isomers have been measured in the fission of ²³⁵U (n. therm. f) and ²³⁵U (n. 3 MeV, f). The results were obtained from γ spectrometry (Ge-Li) gross spectra. The isomeric ratio: Yi(¹³⁶I(45s))/Yi(¹³⁶I(45s))+Yi(¹³⁶I(83s)) is respectively: 0.55+-0.05 (n. therm.) and 0.66+-0.07 (n. 3 MeV). J(RMS) values of: 5.9+-0.4 h and 7.0+-1.0 h are deduced

[en] A simplified method for studying the energetic and spatial statistical properties of ions confined in a quadrupole R.F. trap is proposed. A relation from a property of temporal invariance is deduced, and the results are tested with those obtained previously by a general method