We have developed two types of lightweight active portable neutron survey meter comprising a proportional gas counter with a mixture of methane and nitrogen for measuring the ambient neutron dose equivalent H*(10). One type without using polyethylene moderator has already been published in Journal of Nuclear Science and Technology. Since no heavy polyethylene moderator is used, this neutron survey meter is only about 2.2 kg in weight causing a weight reduction over 70 % compared with the conventional moderatedtype survey meter. The neutron energy response to H*(10) showed very good agreement within about 30% to quasimono-energetic and continuous energy neutrons in actual workplace neutron fields over wide energy region from thermal energy up to about 200 MeV. This survey meter can be used in various accelerator facilities. The neutron energy response of this survey meter was however highly deviated from H*(10) to the mono-energetic neutron fields in the keV region. Then, we have developed another type of lightweight neutron survey meter with inserting a thin (2.5 cm thick) polyethylene moderator in the previous gas counter. This new survey meter has a little heavier weight of 3.5 kg, but still lighter than the conventional polyethylene moderated survey meters of about 7 to 11 kg. This survey meter highly improved the neutron energy response in the keV region to the fluence–to-dose equivalent conversion coefficient and can be appropriately used in nuclear power plants where low energy neutrons occupy mostly. These two types of lightweight neutron survey meters are now commercially available and are widely used in various nuclear facilities.

The flow gas radiochemical method is proposed to be
used for monitoring of neutron flux in high-flux nuclear
reactors, such as the PIK of the St. Petersburg Institute of
Nuclear Physics named by B.P.Konstantinov. A feature

of the technology is the spatial separation of neutron de-
tection and their registration by means of transporting

the resulting radioactive gas 37Ar - a product of a nuclear
reaction in the core with the help of transport gas He to a
remote and protected decay counter. In this formulation,
the technology makes it possible to drastically reduce the
background load from γ-quanta and other competing

processes. To place a detector ampoule in a narrow tech-
nological channel of a PIK nuclear reactor, its dimen-
sions must be very small. A small amount of the active

substance in the detector ampoule, in addition, will re-
duce the decay count and the load on the readout elec-
tronics. In fact, the limiting dimensions of the detector

ampoule can be considered as "pointlike" and such am-
poules can be used to obtain a spatial distribution of the

neutron flux across the core of a high-flux nuclear reac-
tor.

A bipartite and tripartite quantum coherence of a polarized 1/2−XXZ Heisenberg spins chain model with modulated Dzyaloshinskii-Moriya interaction and applied magnetic field is investigated using quantum renormalization group approaches. In a thermodynamic limits, we derived the coherence factor and the monogamy of entanglement of a bipartite and tripartite states of the modulated system. Our analysis show how much the quantum coherence and the monogamy of entanglement decrease in the weak regime of the external magnetic field with the increases of the anisotropy factor and the decreases of the DzyaloshinskyMoriya factor Dz . We observe an interplay between the anisotropy factor and the applied magnetic field and the modulated DM factor. The combined effect of the modulate DM interaction with the applied magnetic field bring correction to the non-analyticity behavior of quantum coherence and of monogamy of entanglement exhibited around the criticalpoint △ = 1 of the anisotropy factor. In addition, we perceive that the non-analytical behavior around the critical value of the anisotropy factor translate quantum phase transition from spin liquid to N´eel phase and vice-versa depending on whether spin is localised on an even or odd site in the chain. The electric field polarisation induced in the chain tens to stabilize the spins in a specific orientations and reenforce correlations which becomes beneficial for ferroelectricity and opened route to switch magnetoelectricity with electric polarazation and vice-versa.