K. Grigoryev

Background reduction by a getter pump around the ionization volume of a Lamb-shift polarimeter and possible improvements of polarized ion sources

The Koln–Julich Lamb-shift polarimeter is used to measure the nuclear polarization of the hydrogen or deuterium beam produced with the atomic-beam source for the polarized target at the ANKE spectrometer at COSY-Julich. The precision of the earlier results had been dominated by the recombination of atoms in the ionizer. Protons or deuterons from the dissociative ionization of unpolarized recombined H2 or D2 molecules had strongly contributed to the extracted ion beam. To suppress this effect, in the new ionizer a nonevaporable getter pump of about 2000l∕s H2 or D2 pumping speed surrounds the ionization volume. It reduces the extracted current of unpolarized ions, produced from the recombined molecular gas, by a factor of about 20 compared with the earlier value, which reduces the error of the polarization measurements to about 0.5%. Now the H2 or D2 molecules in the ionization volume predominantly are those which are contained in the incoming beam from the atomic beam source. This allows the measurement o...

Hyper-Polarized Deuterium Molecules: An Option to Produce and Store Polarized Fuel for Nuclear Fusion?

The use of nuclear-polarized particles is an interesting option to increase the energy output of future fusion reactors or to decrease their costs. However, before polarized particles can be used as polarized fuel studies on production and handling of sufficient amounts of polarized fuels are necessary. This should not be a problem \(\mathrm{for}\ {}{^3}\mathrm{He}\) and T, because both can be polarized by so called “optical-pumping”. Unfortunately, this method has not been very successful in producing polarized deuterium yet. For the use of polarized fuel in magnetic-confinement fusion devices (e.g. in tokamaks) the production of polarized deuterium molecules by recombination of polarized deuterium atoms from a polarized atomic beam source is another option. In first experiments with hydrogen, the initial nuclear polarization of about 0.9 has mostly been preserved during the recombination process on a Fomblin surface. For deuterium polarization losses due to wall collisions are expected to be substantially reduced when the temperature of the deuterium gas is lowered to near liquefaction temperatures. Therefore, storing of polarized deuterium molecules seems to be possible, either as very cold gas in strong magnetic fields, or by freezing out as polarized deuterium ice.

Hydrogen spectroscopy with a Lamb-shift polarimeter - An alternative approach towards anti-hydrogen spectroscopy experiments

AbstractA Lamb-shift polarimeter, which has been built for a fast determination of the polarization of protons and deuterons of an atomic-beam source and which is frequently used in the ANKE experiment at COSY-Jülich, is shown to be an excellent device for atomic-spectroscopy measurements of metastable hydrogen isotopes. It is demonstrated that magnetic and electric dipole transitions in hydrogen can be measured as a function of the external magnetic field, giving access to the full Breit-Rabi diagram for the 22S1/2 and the 22P1/2 states. This will allow the study of hyperfine structure, g factors and the classical Lamb shift. Although the data are not yet competitive with state-of-the-art measurements, the potential of the method is enormous, including a possible application to anti-hydrogen spectroscopy.

A New Application of a Lamb‐shift Polarimeter

With the use of a spinfilter as the most important component of a Lamb‐shift polarimeter, a beam of metastable atoms in one hyperfine state (α1 or α2) can be produced. By induced transitions it seems possible to observe any transition between the 2S1/2 metastable hyperfine states or into the short‐lived states 2P1/2 and 2P3/2 of the hydrogen (deuterium) atom separately as a function of the magnetic field. According to our estimate, the Breit‐Rabi diagrams for these states can be measured with a precison of about 1 kHz (4.2×10−12 eV) or even better. Furthermore, the hyperfine splittings and the Lamb shift can be observed as well.

First Experiments with the Polarized Internal Gas Target (PIT) at ANKE/COSY

For future few‐nucleon interaction studies with polarized beams and targets at COSY‐Julich, a polarized internal storage‐cell gas target was implemented at the magnet spectrometer ANKE. First commissioning of the polarized Atomic Beam Source (ABS) at ANKE was carried out and some improvements of the system have been done. Storage‐cell tests to determine the COSY beam dimensions have been performed. Electron cooling combined with stacking and stochastic cooling have been studied. Experiments with N2 gas in the storage cell to simulate the background produced by beam interaction with the aluminum cell walls were performed to investigate the beam heating by the target gas. The analysis of the dp→dp and dp→(dpsp)π0 reactions showed that events from different positions of the extended target can be clearly identified in the ANKE detector system. The polarization of the atomic beam of the ABS, positioned close to the strong dipole magnet D2 of ANKE, was tuned with a Lamb‐shift polarimeter (LSP) beneath the ...

Deuteron Spin Dichroism: From Theory to First Experimental Results

The production of tensor polarization in an unpolarized deuteron beam after passage through unpolarized carbon targets, which includes the effect of deuteron spin dichroism, has been observed for the first time. Theoretical background, experimental setup, and results of the experiment are presented.

Production and storage of polarized H

The investigation of the recombination of nuclear polarized hydrogen and deuterium atoms into polarized molecules gives new insights into different fields in physics and chemistry. On the one hand, the measurement of the polarization preservation during the recombination process itself allows one the observation of a new parameter during the chemical processes on different surfaces and enables the production of hyper-polarized molecules. On the other hand, the molecular polarization measured as a function of the imposed external magnetic field delivers the coupling forces of the nuclear spins and the rotational magnetic moments of the molecules as well as the coupling between the two nuclear spins themselves. This knowledge allows one to optimize storage-cell gas targets for coming accelerators experiments or to produce and handle polarized fuel for future fusion reactors.

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Abstract The vector and tensor analysing powers, A y and A y y , of the p d → → n { p p } s charge-exchange reaction have been measured at a beam energy of 600 MeV at the COSY-ANKE facility by using an unpolarised proton beam incident on an internal storage cell target filled with polarised deuterium gas. The low energy recoiling protons were measured in a pair of silicon tracking telescopes placed on either side of the target. Putting a cut of 3 MeV on the diproton excitation energy ensured that the two protons were dominantly in the S 0 1 state, here denoted by { p p } s . The polarisation of the deuterium gas was established through measurements in parallel of proton–deuteron elastic scattering. By analysing events where both protons entered the same telescope, the charge-exchange reaction was measured for momentum transfers q ≥ 160 MeV / c . These data provide a good continuation of the earlier results at q ≤ 140 MeV / c obtained with a polarised deuteron beam. They are also consistent with impulse approximation predictions with little sign evident for any modifications due to multiple scatterings. These successful results confirm that the ANKE deuteron charge-exchange programme can be extended to much higher energies with a polarised deuterium target than can be achieved with a polarised deuteron beam.

, D

Abstract The vector and tensor analysing powers, A y and A y y , of the p d → → n { p p } s charge-exchange reaction have been measured at a beam energy of 600 MeV at the COSY-ANKE facility by using an unpolarised proton beam incident on an internal storage cell target filled with polarised deuterium gas. The low energy recoiling protons were measured in a pair of silicon tracking telescopes placed on either side of the target. Putting a cut of 3 MeV on the diproton excitation energy ensured that the two protons were dominantly in the S 0 1 state, here denoted by { p p } s . The polarisation of the deuterium gas was established through measurements in parallel of proton–deuteron elastic scattering. By analysing events where both protons entered the same telescope, the charge-exchange reaction was measured for momentum transfers q ≥ 160 MeV / c . These data provide a good continuation of the earlier results at q ≤ 140 MeV / c obtained with a polarised deuteron beam. They are also consistent with impulse approximation predictions with little sign evident for any modifications due to multiple scatterings. These successful results confirm that the ANKE deuteron charge-exchange programme can be extended to much higher energies with a polarised deuterium target than can be achieved with a polarised deuteron beam.

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M. Mikirtychyants , R. Engels, K. Grigoryev, A. Vasilyev D. Chiladze, A. Kacharava, S. Mikirtychyants, F. Rathmann, J. Sarkadi R. Schleichert, H. Seyfarth, H. Ströher, D. Prasuhn, B. Lorentz S. Barsov and S. Dymov Institut für Kernphysik, Forschungszentrum Jülich, Leo-Brandt-Str. 1, 52425 Jülich, Germany Petersburg Nuclear Physics Institute, Orlova Rosha, 188300 Gatchina, Russia b Laboratory of Nuclear Problems, Joint Institute for Nuclear Research, 141980 Dubna, Russia