10 research outputs found
Dynamics of cubic-tetragonal phase transition in KNbO perovskite
The low-energy part of the vibration spectrum in KNbO was studied by cold
neutron inelastic scattering in the cubic phase. In addition to acoustic
phonons, we observe strong diffuse scattering, which consists of two
components. The first one is quasi-static and has a temperature-independent
intensity. The second component appears as quasi-elastic scattering in the
neutron spectrum indicating a dynamic origin. From analysis of the inelastic
data we conclude that the quasi-elastic component and the acoustic phonon are
mutually coupled. The susceptibility associated with the quasi-elastic
component grows as the temperature approaches T
Spin fluctuations in the stacked-triangular antiferromagnet YMnO3
The spectrum of spin fluctuations in the stacked-triangular antiferromagnet
YMnO3 was studied above the Neel temperature using both unpolarized and
polarized inelastic neutron scattering. We find an in-plane and an out-of-plane
excitation. The in-plane mode has two components just above TN, a
resolution-limited central peak and a Debye-like contribution. The
quasi-elastic fluctuations have a line-width that increases with q like Dq^z
and the dynamical exponent z=2.3. The out-of-plane fluctuations have a gap at
the magnetic zone center and do not show any appreciable q-dependence at small
wave-vectors.Comment: JETP LETTERS, in pres
Disorder and relaxation mode in the lattice dynamics of PbMgNbO relaxor ferroelectric
The low-energy part of vibration spectrum in PbMgNbO
relaxor ferroelectric was studied by inelastic neutron scattering. We observed
the coexistence of a resolution-limited central peak with strong quasielastic
scattering. The line-width of the quasielastic component follows a
dependence. We find that is temperature-dependent.
The relaxation time follows the Arrhenius law well. The presence of a
relaxation mode associated with quasi-elastic scattering in PMN indicates that
order-disorder behaviour plays an important r\^ole in the dynamics of diffuse
phase transitions
Short-range correlations studies in collisions of polarized nuclei at Nuclotron-M
The status and prospects of 2-nucleon and 3-nucleon short range correlations (SRCs) studies at Nuclotron-M (JINR) are presented. This program is focused on the investigations of the spin part of SRCs with polarized deuteron beam from new high intensity polarized deuterons ion source which is under development at JINR. The wide experimental program on the systematic studies of the polarization effects in dp- elastic scattering, dp- nonmesonic breakup, dd → 3Hen(3Hp) and d3He → p4He reactions sensitive to SRCs using both internal and extracted beam at Nuclotron-M is presented
Study of strange matter production in the heavy ion collisions at NUCLOTRON
It is proposed to install an experimental setup in the fixed-target hall of the Nuclotron with the final goal to perform a research program focused on the production of strange matter in heavyion collisions at beam energies between 2 and 6 A GeV. The basic setup will comprise a large acceptance dipole magnet with inner tracking detector modules based on double-sided Silicon micro-strip sensors and GEMs. The outer tracking will be based on the drift chambers and straw tube detector. Particle identification will be based on the time-of-flight measurements. This setup will be sufficient perform a comprehensive study of strangeness production in heavy-ion collisions, including multi-strange hyperons, multi-strange hypernuclei, and exotic multi-strange heavy objects. These pioneering measurements would provide the first data on the production of these particles in heavy-ion collisions at Nuclotron beam energies, and would open an avenue to explore the third (strangeness) axis of the nuclear chart. The extension of the experimental program is related with the study of in-medium effects for vector mesons decaying in hadronic modes. The studies of the NN and NA reactions for the reference is assumed