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We report measurements of enhanced tensor polarization on solid-state targets. The results here represent an increase in tensor polarization over that previously achieved in high energy and nuclear scattering experiments that focu...
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We report measurements of enhanced tensor polarization on solid-state targets. The results here represent an increase in tensor polarization over that previously achieved in high energy and nuclear scattering experiments that focused on the measurement of tensor polarized observables. Enhancement techniques are used which require RF produced close to the Larmor frequency of the target spins and use selective semi-saturation resulting from two sources of irradiation, microwave for the DNP process and the additional RF used to manipulate the population of the energy levels in the target material. The spin dynamics of the solid target are used to align the spins enhancing the ensemble average to improve the figure of merit of the scattering experiment. Target rotation at an optimized rate can lead to additional enhancement by applying selective semi-saturation in polycrystalline materials that possess a Pake doublet in their NMR signal.
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A novel source of polarized hydrogen and deuterium molecules has been tested. The use of sextupole superconducting magnets allows us to select molecules with the nuclear spin projection -1 for hydrogen and -2 for deuterium. The me...
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A novel source of polarized hydrogen and deuterium molecules has been tested. The use of sextupole superconducting magnets allows us to select molecules with the nuclear spin projection -1 for hydrogen and -2 for deuterium. The measured beam intensity of polarized hydrogen molecules for the nozzle temperature range of 6.5-30 K and a gas flow rate up to 5 · 10~(-2) Torr • 1/s is presented. The measured flux of polarized hydrogen molecules of ≈ 3 • 10~(12) mol/s is in reasonable agreement with estimations. The obtained results can be used as a basis for the development of a high-intensity source of polarized molecules.
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Experience with polarized targets and the achievement of very low temperatures at the Laboratory of Nuclear Problems (JINR, Dubna) and at other places have triggered the idea of using a radically new technique based on dissolving ...
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Experience with polarized targets and the achievement of very low temperatures at the Laboratory of Nuclear Problems (JINR, Dubna) and at other places have triggered the idea of using a radically new technique based on dissolving ~3He in ~4He to create a frozen spin polarized target. The short history of the development of such proton and deuteron targets at the LNP is given. Diols with the complex Cr(Ⅴ) are used as target materials. A characteristic feature of these targets is the long relaxation time (≈ 1000 h) in magnetic fields of about 0.5 T. Lately, the Saclay-Argonne frozen spin polarized proton target used initially in the E704 experiment at FERMILAB has been upgraded by adding the missing parts. A first physics experiment has been carried out.
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An experimental program has been started at MAMI and ELSA to measure the integrand of the Gerasimov-Drell-Hearn sum rule (GDH) in a photon energy range starting from the pion threshold up to 2.9 GeV. A polarized target has been bu...
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An experimental program has been started at MAMI and ELSA to measure the integrand of the Gerasimov-Drell-Hearn sum rule (GDH) in a photon energy range starting from the pion threshold up to 2.9 GeV. A polarized target has been built, which is based on the frozen spin technique. Since the value of the nucleon polarization and the areal density of the target contribute directly to the result of the GDH-integral both quantities have to be determined with high accuracy.
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From 1983 to 2002, the Indiana Cooler was constructed and operated at the Indiana University Cyclotron Facility. During that period, a relatively small group of people built an accelerator complex, explored the new technology of e...
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From 1983 to 2002, the Indiana Cooler was constructed and operated at the Indiana University Cyclotron Facility. During that period, a relatively small group of people built an accelerator complex, explored the new technology of electron cooling, and demonstrated its usefulness in nuclear and particle physics. This review recounts the history of the project, describes the facility, and summarizes the scientific results in atomic, nuclear, and particle physics, and in the physics of beams.
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Polypropylene track membranes made by irradiation of polypropylene films with a beam of high-energy heavy ions followed by chemical etching of latent ion tracks are proposed for being used as a polarized target material. To give m...
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Polypropylene track membranes made by irradiation of polypropylene films with a beam of high-energy heavy ions followed by chemical etching of latent ion tracks are proposed for being used as a polarized target material. To give membranes paramagnetic properties needed for allowing dynamic polarization of nuclei, the nitroxyl radical 2,2,6,6-tetramethylpiperidine-1-oxyl was introduced in the samples by the thermal diffusion technique. Using the electron paramagnetic resonance method, we obtained information on paramagnetic centers in the polymer matrix of the membranes and determined the nitroxyl radical concentration and rotational mobility of the spin probe in them.
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We report the perpendicular plane ionization results of (e, 2e) triple-differential cross sections for the Ne(2p) and Ar(3p) atoms at the incident electron energies ranging from 5 to 50 eV above ionization potential for neon atoms...
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We report the perpendicular plane ionization results of (e, 2e) triple-differential cross sections for the Ne(2p) and Ar(3p) atoms at the incident electron energies ranging from 5 to 50 eV above ionization potential for neon atoms and from 2 to 50 eV above ionization potential for the argon atoms. The present investigation has been done in the modified distorted wave Born approximation and it has been observed that postcollision interaction and polarization of target are important in the perpendicular plane ionization of atoms. We also present the results of triple-differential cross section for the doubly symmetric coplanar ionization of Na(3s) atoms at the incident electron energy ranging from 6 to 60 eV above ionization potential. Thus we are able to see the effects of target polarization and postcollision interaction in coplanar as well as the perpendicular plane geometrical conditions. The results of our calculations for the Ne(2p) and Ar(3p) have been compared with the very recent measurements of Nixon et al. [K. L. Nixon, A. J. Murray, and C. Kaiser, J. Phys. B 43, 085202 (2010)] and the results of coplanar ionization of Na(3s) have been compared with the experimental data of Murray [A. J. Murray, Phys. Rev. A 72, 062711 (2005)]. It is observed that there are certain discrepancies between theoretical and experimental results which indicate that further theoretical efforts are required to understand the cross section trends of neon, argon, and sodium atoms. The cross section in the perpendicular plane ionization exhibits complex variations as a function of incident energy and target.
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The factors are reviewed that can affect the systematic uncertainties in CW-NMR measurements of the polarization in solid state polarized targets. The main problem with large signals, typically obtained with protons, is non-linear...
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The factors are reviewed that can affect the systematic uncertainties in CW-NMR measurements of the polarization in solid state polarized targets. The main problem with large signals, typically obtained with protons, is non-linearity arising from failure of the constant RF drive current assumption. The non-linearity can be reduced by operation at lower than normal signal levels. With the much smaller size deuteron signals, a limiting factor may be the instability of the background signal generated by the resonant length cable, used in the standard system. A new system is demonstrated, using non-resonant length cables, which is expected to reduce these uncertainties to a low level.
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A spectrum of virtual photons is analyzed in the reaction of electroproduction of negative pions on a deuteron when both finite protons are registered and their escape energies and angles are determined.
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