Presentation on theme: "A Proposal of a Polarized 3 He ++ Ion Source with Penning Ionizer for JINR N.N. Agapov, Yu.N. Filatov, V.V. Fimushkin, L.V. Kutuzova, V.A. Mikhailov, Yu.A."— Presentation transcript:
A Proposal of a Polarized 3 He ++ Ion Source with Penning Ionizer for JINR N.N. Agapov, Yu.N. Filatov, V.V. Fimushkin, L.V. Kutuzova, V.A. Mikhailov, Yu.A. Plis, Yu. V. Prokofichev, V.P. Vadeev Joint Institute for Nuclear Research, Dubna, Russia
§Goal is to make an intensive polarized 3 He ++ beam in the JINR superconducting accelerator NUCLOTRON. The installation of the 3 He ++ polarized ion source at the accelerator complex of JINR, Dubna will allows to continue the spin physics experiments. This is an important part of the Laboratory of High Energies scientific program.
§The source will consist of an apparatus for for polarizing of 3 Не and for ionizing of polarized 3 Не gas.
§Rb - 3 Не polarizer §There are two methods of the 3 Не-gas polarization, namely: -by spin exchange with an opticallly pumped Rb-vapour, and -by metastability exchange scattering with optically pumped metastable 3 Не-atoms in their 1s 2s 3 S 1 -state §Our option is Rb- 3 Не method.
§Rb- 3 Не polarizer hardware. §Rb- 3 Не polarizer includes FAPSYSTEM (COHERENT production) 25W laser ( Wavelength - 795 nm, Width - 2 nm ), §optical system, §glass polarizing cell ( 3 Не, Rb, N 2 ), §cell baking and Rb distillation, §refilling system ( 3 Не – N 2 mixture), § magnet coils system, 3 Не system of cryosorption purification, §system of polarization measurements ( NMR – polarimeter ).
§Optical system involves polarizing cube, mirrors, lenses, /4 plates. §It is supposed to use pyrex glass(Corning7740) cells.
§Polarizing cell parameters §Volume - 100 cm 3 § 3 Не pressure – 1.5-3 bar §Cell temperature - 180-200 о С
§Magnet system consisting of four coils will provide for the 100 Gs magnetic field with a degree of homogeneity 10 -4
§NMR detection is the most important tool for monitoring the polarization process. §This is possible to do measuring the signal of the forced precession. §The project polarization of 3 Не gas into 0.1 l·bar cell is 50%.
Rb- 3 Не polarizer §1. magnet system 2.optical system 3.support 4. glass polarizing cell ( 3 Не, Rb, N 2 ) 5. cell baking system 6. polarimeter coil
§It is known the polarized gas can be moved from the polarizing field of Rb- 3 Не polarizer in a special container saving polarization. §We would like to use this possibility having the special movable 3 Не-cell and attach this one to ionizer. §This is convenient under accelerator conditions.
3 He-polarized gas container §1. 3 Не transport cell 2. permanent magnet
§ 3 Не polarized beam is injected into an ionization volume restricted by drift Al-tubes system through a 0.1mm capillary. §Capillary gas flow is about 1 cm 3 /hour or less.
§The ionizer is based on the Electron Beam Ion Source (EBIS) in the reflex mode of operation processes and Penning ionizer. §Principle of operation is the 3 Не ++ ion accumulation in the ion trap with the following 10 μs pulse extraction.
§The electrostatic voltage distribution on drift tubes at accumulation and extraction. Diagram of the of the project ionizer
§The ion trap is produced by space charge of oscillating electrons in a drift tubes region. In the same place the ionization by an electron impact is accomplished also. §In radial direction the electron cloud is holded by 1 T solenoid magnetic field. This field is needed to exclude 3 Не gas depolarization on the walls of drift tubes. §It is scheduled to use Ne-Fe-B permanent magnet for the ionizer.
§Project ionizer parameters: §Energy of electrons – 10-20 keV §Effective current – 5-20 A §Length of ion trap – 1 m § 3 Не ++ ion beam intensity - 2 10 11 5 10 11 electronic charge/pulse
The advantages of this type of ionizer - high factor of ionization is not required in other words the 3 Не holding time in the ion trap is short, - ultrahigh vacuum is not required in comparison with EBIS ionizer,
§It is scheduled to accumulate the volume charge of electrons in trap at 10-15 keV electron energy up to § 5 10 11 - 10 12 electronic charge §and obtain 3 Не ++ polarized beam intensity up to § 2 10 11 5 10 11 electronic charge/pulse §from the source.
§Ionizer consists of a vacuum chamber, Ne-Fe-B- permanent magnet system, electron optical system ( electron gun, electron optical structure and ion optics ), ionizator control system, 20 kV modulator, 10 μs system of a fast extraction and remote control system.
§At the exit of the ionizer we have to install a spin-precessor for 3 Не ++ space spin orientation as the concording apparatus with direction of the accelerator magnetic field. §The spin-precessor includes a spherical electrostatic mirror and solenoid
Schematic view of the 3 Не ++ polarized source §1.electron gun 2.drift tube sections 3. electron reflector 4. ion optical lens 5. movable Faraday cup 6. Nd B Fe permanent magnet 7.turbomolecular pump 8.spherical electrostatic mirror 9. spin precessor solenoid 10. flexible permanent magnet and magnetic shield 11. movable cell 12. capillary.
About 3 Не + depolarization in time of ionization:
At NUCLOTRON parameters we have the following resonances: