Yu. V. Prokofichev

On the KaTRIn project for an experimental study of time-reversal violating effect in polarized neutron propagation through a polarized target

Abstract KaTRIn is the project aimed at building an experimental setup for checking the time-reversal invariance in polarized neutron propagation through a polarized target. A measurement method proposed recently consists in 180° rotation of the neutron polarizer around the target. The method requires only one neutron polarizing device and excludes a number of false effects. The 3He-based neutron polarizer has great advantages for this task. We describe the design of the Rb3He polarizer prototype. The standard NMR technique is used to measure the obtained 3He polarization. The idea of pulse polarized target is discussed.

Superconducting shield for solenoid of electron cooling system

Ensuring the high homogeneity of a magnetic field in the straight solenoid of an electron cooling system is a very important task. In the electron cooling system of the collider in the NICA project, it is planned to use superconducting solenoids for the generation of a longitudinal magnetic field. Using of the superconducting shield is proposed to achieve the required homogeneity of the magnetic field in the cooling section. This article discusses the design of the superconducting shield and presents experimental and numerical studies into the homogeneity of the magnetic field in solenoids with the superconducting shield.

The new source of polarized ions for the JINR Accelerator Complex

The project assumes the design and construction of a universal high-intensity source of polarized deuterons (protons) using a charge-exchange plasma ionizer. The output ↑D+ (↑H+) current of the source is expected to be at a level of 10 mA. The polarization will be up to 90% of the maximal vector (±1) for ↑D+ (↑H+) and tensor (+1,−2) for ↑D+ polarization. Realization of the project is carried out in close cooperation with INR of RAS (Moscow). The equipment available from the CIPIOS ion source (IUCF, Bloomington, USA) is partially used for the Dubna device. The new source at the JINR NUCLOTRON accelerator facility will make it possible to increase the polarized deuteron beam intensity up to the level of 1010 d/pulse. Previous test runs on acceleration of polarized deuterons at the NUCLOTRON up to about 1 GeV/u and slow extraction of the beam to the beam transfer lines, have shown the absence of depolarization resonances. The first dangerous resonance is predicted at the beam energy of 5.6 GeV/u. The source could be transformed into a source of polarized negative ions if necessary.

Neutron spin filter based on optically polarized in a near-zero magnetic field

Abstract A test of polarization of 3 He nuclei via spin-exchange collisions with optically pumped rubidium atoms in an extremely low applied magnetic field was carried out. Permalloy magnetic shields were used to prevent a fast relaxation of 3 He polarization owing to the inhomogeneity of a surrounding magnetic field. The whole installation was placed at the neutron beam line of the IBR-30 facility, and used as a neutron spin filter. Thus, a prototype of new design of neutron polarizer was introduced. We intend to apply this experience for the full-scale KaTRIn facility to test the time reversal violation in neutron-nuclear reactions.

Source of polarized ions and polarized beams at the NUCLOTRON

The paper describes the JINR polarized ion source operating by means of the atomic beam method. The results of testing of the plasma ionizer with a storage cell and tuning of high frequency transition units are presented. The source was installed in the linac injector hall of the NUCLOTRON in May 2016. The source was commissioned and used in the NUCLOTRON runs in 2016 and February – March 2017. Polarized and unpolarized deuteron beams as well as polarized proton beam were produced to accelerate in the NUCLOTRON. The polarized deuteron beam with pulsed current up to 3.7 mA has been produced. Deuteron beam polarization of 0.6-0.9 of theoretical values for different modes of high frequency transition units has been measured with the NUCLOTRON ring internal polarimeter for the accelerated deuteron and proton beams.

Transition of polarized ions through the system of ring permanent magnets

The task of the transportation of the polarized proton and deuteron beam of an energy 10-20 keV in the given magnetic field is considered. Specifically the magnetic field is produced by the system of a solenoid and some ring permanent magnets with contrary directed field. The Lorentz equations together with classic equations for vector and tensor polarizations have been solved. The results of the numerical simulation for a simple two- ring system are presented, which shows there is no essential depolarization in agrement with theoretical estimation.

Development of polarized ion source for the JINR accelerator complex

Status of the JINR polarized ion source development is described. The source is under tests at the test-bench of LHEP, JINR. A charge-exchange plasma ionizer has been tested initially without a storage cell in the ionization region. An unpolarized deuterium ion beam with peak current of 160 mA, 23 keV energy, pulse duration of 100 μs and repetition rate of 1 Hz has been extracted from the ionizer. With a free polarized atomic hydrogen beam injected into the ionizer a polarized proton beam with peak current of 1.4 mA has been obtained. The nearest plans for the source development include tests of the ionizer with the storage cell and tuning of the high frequency transition units installed in their operating position with a Breit-Rabi polarimeter.

Status of the polarized ions source for the JINR accelerator complex

The project assumes the design and construction of a universal high-intensity source of polarized deuterons (protons) using a charge-exchange plasma ionizer. The output D+↑ (H+↑) current of the source is expected to be at a level of 10 mA. The polarization will be up to 90% of the maximal vector (±1) for D+↑ (H+↑) and tensor (+1, −2) for D+↑ polarization. Realization of the project is carried out in close cooperation with INR of the RAS (Moscow). The equipment available from the CIPIOS ion source (IUCF, Bloomington, USA) is partially used for the Dubna setup. The new source at the JINR Nuclotron accelerator facility will make it possible to increase the polarized deuteron beam intensity up to the level of 1010 d/pulse. The first results of the source of polarized atoms testing are presented.

A PROPOSAL OF POLARIZED 3HE++ ION SOURCE WITH PENNING IONIZER FOR JINR

A polarized 3He++ beam can be accelerated in NUCLOTRON. This gives an opportunity to study the feasibility of 3He++ production by ionization of polarized 3He gas in the Penning ionizer using of an ion trap and pulse extraction. The 3He gas can be polarized by the technique of Rb-3He spin exchange optical pumping. The expected intensity of polarized (up to 50%) 3He++ ions can be 5 x 10l1 electronic charge/pulse.