Electric magnet for spectrometry of neutron decomposition

FIELD: nuclear physics.

SUBSTANCE: device realizes electric magnet for spectroscopy of decomposition of neutron, with current configuration, providing magnetic field of 1/R type, where R - radial distance from device axis. Magnet includes no iron and field is fully absent at distance of near 25 cm and more from its outer surface. Device has two hollow semi-cylinders which connect through Φ-like flanges. This capability is achieved due to use in construction of each semi-cylinder of two coaxial semi-pipes, supported by their edges by setting grooves of flanges, containing elements for pressurization and centering.

EFFECT: higher trustworthiness, higher reliability, higher durability, higher precision.

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The invention relates to the field of experimental nuclear physics, in particular to a device for magnetic spectrometry of charged particles and study of neutron decay.

Known proposals and device for measuring the so-called P-odd (spatial) correlations in the decay of polarized neutrons [1]. In these devices using a magnetic field generated by the solenoid, the decay electrons, emitted along and against the direction of the spin of the neutron, are sent to the detectors, which register the count rates of electrons depending on the direction of the momentum of the electrons. Then measure the count rate when the change in the polarization of the neutron beam relative to the field. The result is the asymmetry of the electron relative to the back of the collapsed neutron. A disadvantage of devices of the type solenoid is the presence of systematic errors associated with the heterogeneity of the field along the axis of the solenoid, which causes the effect of the magnetic mirror, distorting the natural asymmetry of the decay. In this situation it is desirable to use a completely different method, have other sources of systematic errors and, of course, a higher resulting precision.

On set of used signs closest to the proposed solution is a magnet known trochoidal range of the meter Malmfors [2]. The magnet includes a horizontal circular coil of rectangular cross-section, is surrounded on the outside by an iron yoke, paired with a tapered poles that are installed symmetrically with respect to the cross-section average coil horizontal plane of symmetry. The gap between the pole tapers from the inner wall of the coil to the center, and the walls of the gap function as the vacuum chamber and form a working area for the movement of positrons and electrons.

The spectrometer Malmfors was used as time-of-flight spectrometer for analysis of the spectra of electrons and positrons, born in the birth of a pair near the mid-plane gap. The source of electrons and positrons is almost a point.

The aim of the proposed device is the enhanced functionality with a study of correlations in the decay of polarized neutrons and increase in intensity.

This goal is achieved by the fact that:

the winding of the electromagnet is in the form of two sets of rectangular coils, each of which is hosted by forming two coaxial cylindrical cut longitudinally semitubes, narashima-United on the ends of the parallel plates in the form of a half disc with a hole, and comprises a u-type and plates contain guides for mounting coils, edge polytrope of palutikof combined in the same plane and are connected by a welded connection with a rectangular C-shaped flange, having two equal rectangular Windows separated by a Central crosspiece, corresponding in size to the diameter and the length of the center comprises a u-type;

the flanges are provided with sealing elements located at the edges of rectangular Windows, and a device for combining and screed flange.

The device illustrated in the drawing, in which figure 1 shows schematically a view of an electromagnet with an end face and a window for entering the neutron beam, and figure 2 shows half of the vacuum chamber and schematically shows the arrangement of a coil end part and the outer polytrope.

The device consists of two poloxamer containing the flanges 1, to which is welded vacuum-durable seam comprises a u-type Central 2 and outer 3 comprises a u-type, connected, in turn, end paludisme 4. Polyamory bear the fastening elements of the turns of the winding 5, between which the stacked coils 6. The coils are symmetrical and tightly fill the volume of the Central semitubes, radially located on the end paludismo and placed symmetrically to the generatrix of the outer comprises a u-type, single winding. Polyamory are aligned with holes and bolt or other compounds, forming a single volume around the Central tube of the tire formed by the joining of the Central semitubes. Vacuum pumping this volume and the input of neutrons can be produced through the nozzles, the positioning in the Windows in the winding. The location of these nozzles in each variant of a magnet depends on its location relative to the neutron beam. To use superconducting materials can be provided by immersing the assembled camera in the cryostat with liquid helium or cavity for pumping the liquid helium under pressure.

The device operates as follows. The coils are made of a single wire or connected so that the current flows in one direction in the Central semitubes and in the opposite direction on the outer semitubes. The symmetrical arrangement of the outer sections of the coils provides an axially symmetric field of the type 1/r between the Central and outer parts of the winding. The external field is very close to zero at distances of a few centimetres. The solution provides the ability to get the field this configuration, in a large volume, which distinguishes it from the prototype. If you use the full current of about 1 Megaampere, the field strength in the entire volume will be sufficient for transporting the protons and electrons from the decay of neutrons. When the input beam of neutrons through the window in the end or side walls of the chamber along the Central bus or perpendicular to it is possible to collect protons and electrons from the collapsed during migration camera neutrons and register them with the help of detectors located inside the chamber, eposredstvenno near the radial end of the winding elements. I.e. the solid angle of collection of particles of decay of a particular zone of the beam is equal to 4π, ie the maximum possible aperture. Controlled length of the beam is determined by the length of the camera and technical capabilities for winding of magnet. It appears that the length of about 2 m and a diameter of about 0.8 m are achievable from a technical point of view.

Economic efficiency is evident when comparing the operating costs of experimentation to achieve the specified accuracy. A large aperture and versatility magnet for research three spatial correlations in the decay of polarized neutrons give ground for higher values of efficiency parameter E, which in this case is E = precision/cost. I.e. the increase in precision (the precision is the inverse of the error in relative units) by reducing errors promises higher growth than the relative increase in the cost of building and operating a magnet.

References

1. D. Dubbers et al. Europhys. Lett. 1990, 11(3), 195.

2. Alpha-, beta - and gamma-spectroscopy. Edited Ciglana. M: Atomizdat, 1969, vol. 1, str-158.

Electromagnet for spectroscopy of neutron decay, containing the coil and the vacuum chamber, characterized in that the winding of the electromagnet is in the form of sets of rectangular coils, to whom each of which is hosted by forming two coaxial cylindrical cut longitudinally semitubes, narashima-United on the ends of the parallel plates in the form of a half disc with a hole, and comprises a u-type and plates contain guides for mounting coils, edge semitubes and palutikof combined in the same plane and are connected by a welded connection with a rectangular C-shaped flange having two equal rectangular Windows separated by a Central crosspiece, corresponding in size to the diameter and the length of the center comprises a u-type; flanges provided with sealing elements located at the edges of rectangular Windows, and a device for combining and screed flange.



 

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