Experiments on A-like to B phase transitions of He-3 confined to aerogel

We have done pulsed and CW NMR studies of A-like to B phase transition in superfluid He-3 confined within aerogel with 98% porosity. The experiments were performed at pressure of 25.5 bar and in magnetic field of 284 Oe and I kOe. A kinetics of the transition is found to be different for pure He-3 in aerogel and for the cell preplated with He-4

Pulsed NMR experiments in superfluid He-3 confined in aerogel

Pulsed NMR experiments have been performed in both B and supercooled A phases of superfluid He-3 in aerogel. Dependencies of spin precession frequency on tipping angle in B-phase of superfluid He-3 in aerogel are found to be different for pure He-3 and for the cell preplated with He-4. A sharp increase of the frequency for tipping angles greater than 104degrees was observed in low temperature superfluid phase of He-3 in He-4 preplated aerogel as it is expected for the B-phase structure of the order. parameter. Dependencies of the frequency on the tipping angle in supercooled A-phase are similar for both pure He-3 and He-4 preplated aerogel. (C) 2003 Elsevier Science B.V. All rights reserved

Measurements of longitudinal and transverse magnetic relaxation in superfluid He-3 confined to aerogel

We present results of pulsed NMR measurements of magnetic relaxation in liquid He-3 in aerogel. It vas found that both longitudinal and transverse relaxation starts to change below the temperature of the superfluid transition of He-3 in aerogel. Below T-c(a) the longitudinal relaxation depends on the initial tipping angle

Nonlinear NMR in a superfluid B phase of He-3 in aerogel

The properties of liquid He-3 in a low-density aerogel preliminarily covered with a few monolayers of He-4 were studied by pulsed and nonlinear CW NMR techniques. It was found that an NMR frequency shift from the Larmor value exhibits a sharp increase at a magnetization tilting angle exceeding 104degrees. Nonlinear CW NMR signals related to the formation of a macroscopic region featuring homogeneous precession of the magnetization (homogeneous precession domain) were observed. The experimental results confirm that the low-temperature superfluid He-3 phase in the aerogel is analogous to the B-phase in bulk He-3 and indicate that the spin supercurrents play an important role in the spin dynamics of superfluid He-3 in aerogel. (C) 2002 MAIK "Nauka / Interperiodica"

Homogeneous spin precession in superfluid He-3 confined to aerogel

We report on systematic studies of creation and relaxation of a macroscopic region of homogeneous spin precession (homogeneously precessing domain-HPD) in B-like phase of He-3 in aerogel. Long lived free induction decay signal has been observed after filling up the whole cell with the HPD and switching off the CW radiofrequency field. Characteristics of CW NMR and free induction decay signal were found to be similar to those known for bulk He-3-B

How occupational health is assessed in mine workers in Murmansk Oblast

Objectives. We aimed to describe how work exposure and occupational health is assessed for mine workers in Murmansk Oblast, Russia. Study design. A descriptive study based on current practice, laws and available literature. Methods. The information and data were obtained from scientific publications, reports, regional and federal statistics, legal documents, through personal visits and onsite inspections. Results. Several institutions are involved in these assessments, but all mine workers have been examined by specialists at one institution, which helps to ensure that the work is of stable quality and adds reliability value to the numbers. Workplace risks are assigned hazard grades, which influence the frequency of periodic medical examinations and salary levels. The examinations are aimed to diagnose latent or manifest occupational disease. This may lead to relocation to a workplace with lower exposure levels, free medical treatment, compensation and a lower pension age. Conclusions. Regulations and systems to protect the health of mine workers have more emphasis on control and repair than on prevention. Since relocation can lower the salary, some workers may under-report medical problems. To what degree this happens is unknown. The mining enterprises pay the medical service provider for periodic medical examinations, which could potentially weaken their independent role. This framework is important to understand when studying and assessing the health of working populations in the circumpolar region