New track interval radon exposure meters (operating principle and design).

The operating principle of innovative interval radon exposure meters INERAD (types IE-2 and IE-4) is described. The major technical features of the both models have been standardized as much as possible. The exposure meters use the LR-115 type 2 track threshold detector, which is sensitive to alpha particles.

The results of long-term simultaneous measurements of radon exhalation rate, radon concentrations in soil gas and groundwater in the fault zone.

The regular monthly radon measurements were carried out in the fault zone on the Western slope of the Beshtau magmatic massif (North Caucasus). The radon exhalation rate from the soil surface, as well as radon concentrations in soil gas at a depth of 0.5 m and in groundwater discharged at a spring located nearby have simultaneously been measured. High seasonal fluctuations in radon exhalation and radon concentration in soil gas, characterized by highs in summer and lows in winter, were registered. In summer, the radon exhalation reached 23.8 Bq m-2s-1, and the radon concentration in the soil gas reached 166 kBq m-3. In winter, both the radon exhalation and the radon concentration in the soil dropped to 0.025 Bq m-2s-1 and <3 kBq m-3, respectively. The concentration of radon in ground water varied over the year in a relatively narrow range (100-210 Bq l-1), and there were no seasonal fluctuations. A sharp increase in soil radon and radon exhalation in spring and a fall in autumn are timed to the moments when the temperature of the atmospheric air becomes, respectively, higher and lower than the temperature of the rock massif. Both the soil radon concentration and the radon exhalation show a close correlation with the temperature of atmospheric air, but in the first case the relationship is linear, and in the second - exponential. The obtained data confirm the assumption that the seasonal radon variations are caused by atmospheric air circulation in the shallow area of the fault due to the temperature difference between the atmosphere and the rock massif.

Application of coupled nanoscale resonators for spectral sensing.

In this paper we propose a method to perform tunable spectral sensing using globally inhibitory coupled oscillators. The suggested system may operate in the analog radio frequency (RF) domain without high speed ADC and heavy digital signal processing. Oscillator arrays may be made of imprecise elements such as nanoresonators. Provided there is a proper coupling, the system dynamics can be made stable despite the imprecision of the components. Global coupling could be implemented using a common load and controlled by digital means to tune the bandwidth. This method may be used for spectral sensing in cognitive radio terminals.

Particle directionality and trapped proton fluences on LDEF.

Directionality of incident space radiation is a significant factor in spacecraft shielding and astronaut dosimetry in low Earth orbit (LEO). Particle directionality of GCR and trapped protons were measured on LDEF with plastic nuclear track detectors (PNTD) from the P0006 west-side experiment. This experiment consisted of a thick detector stack and is described more fully in a companion article (Benton et al., 1996). The anisotropy of the trapped protons produced maximum intensity for protons arriving from the west. The fluences of the eastward directed trapped protons have been measured by selection of the particles on the basis of range in the PNTDs. The measured fluences are compared with the model calculations of Armstrong and Colborn (1993).

Recent results of the joint ESA-DARA/IBMP experiments Biokosmos "Seeds".

Comparison of experimental data obtained from short (SDEF) and long duration exposure flights (LDEF) have recently led to results which will be significant for longer and/or repeated sojourn of man in space. Under orbital conditions biological stress and damage are induced in test subjects by cosmic radiation, especially the high energetic, densely ionizing component of heavy ions. Plant seeds were successful model systems for a biotest in studying the physiological damages and mutagenic effect caused by ionizing cosmic radiation in particular stem cells. Dosimetrically, the subdivision into charge- and Let-groups reveals the contribution of the intermediate group (LET = 350-1000 MeV/cm) due to the medium heavy ions (Z = 6-10). Their relative contribution increases with the lower inclination of the orbit of LDEF-1; on the other hand, the total fluence becomes higher with longer duration of the flight. The observed endpoints of the biological radiation damage hint at a correlation with particle dose rate rather than with the dose; additionally, data on shielding effects inside and outside the space craft and its exposure were gained from the different SDEF- and LDEF-missions.

Multiplicities of secondaries in nuclear interactions, induced by 20Ne, 40Ar and 56Fe nuclei at 0.1-0.5 GeV/nucleon.

Multiplicities of various species of charged secondaries produced in inelastic interactions of 20Ne, 40Ar and 56Fe nuclei with emulsion nuclei at 0.1-0.5 GeV/nucleon have been measured. The data obtained are compared with the results for interactions of higher energy nuclei with emulsion nuclei. The dependences of the nucleus-nucleus interaction parameters on masses and energies of colliding nuclei are examined.

Dependence of the multiplicities of secondary particles on the impact parameter in collisions of high-energy neon and iron nuclei with photoemulsion nuclei.

A method is proposed for finding the dependence of mean multiplicities of secondaries on the nucleus-collision impact parameter from the data on the total interaction ensemble. The impact parameter has been shown to completely define the mean characteristics of an individual interaction event. A difference has been found between experimental results and the data calculated in terms of the cascade-evaporation model at impact-parameter values below 3 fm.

Target fragments in collisions of 1.8 GeV/nucleon 56Fe nuclei with photoemulsion nuclei, and the cascade-evaporation model.

Nuclear photographic emulsion is used to study the dependence of the characteristics of target-nucleus fragments on the masses and impact parameters of interacting nuclei. The data obtained are compared in all details with the calculation results made in terms of the Dubna version of the cascade-evaporation model (DCM).

Multiplicities of secondaries in interactions of 1.8 GeV/nucleon 56Fe nuclei with photoemulsion and the cascade evaporation model.

A nuclear photographic emulsion method was used to study the charge-state, ionization, and angular characteristics of secondaries produced in inelastic interactions of 56Fe nuclei at 1.8 GeV/nucleon with H, CNO, and AgBr nuclei. The data obtained are compared with the results of calculations made in terms of the Dubna version of the cascade evaporation model (DCM). The DCM has been shown to satisfactorily describe most of the interaction characteristics for two nuclei in the studied reactions. At the same time, quantitative differences are observed in some cases.