NUCLEAR ORIENTATION EXPERIMENTS WITH Pr142 AND Yb175 NUCLEI

1958 ◽  
Vol 36 (8) ◽  
pp. 997-1009 ◽  
Author(s):  
J. M. Daniels ◽  
J. L. G. Lamarche ◽  
M. A. R. Le Blanc
Keyword(s):  
Magnetic Fields ◽  
External Field ◽  
Magnetic Moment ◽  
Low Temperatures ◽  
Nuclear Orientation ◽  
Magnesium Nitrate ◽  
Spin Hamiltonian ◽  
Crystal Axis ◽  
Γ Ray ◽  
Made In

Pr142 has been oriented as an impurity in cerium magnesium nitrate, and the anisotropy of the 1.57 Mev γ-ray was measured as a function of temperature in the range 0.003° K to 1.0° K, both in zero external field and in a field of 320 gauss parallel to the trigonal crystal axis. The results are not consistent with what has been published about the spin Hamiltonian of Pr+++ in this lattice. The magnetic moment of Pr142 is very small, and it was not possible to see any saturation of the anisotropy at low temperatures. Values for the magnetic moment of Pr142 were found for two different assumed decay schemes, these are 0.11 nuclear magnetons for the spin assignments [Formula: see text], and 0.15 nuclear magnetons for the spin assignments [Formula: see text]. Similar experiments were carried out on Yb175. Measurements were made in a variety of external magnetic fields up to 700 oersted, and at temperatures as low as 0.003° K. No anisotropy was observed for the 396 kev γ-ray, nor for the 282 kev γ-ray. The most likely explanation for this result is that the lifetime of the γ-emitting state is about 10−10 seconds. The relation between the results of this experiment and others on the same isotope (Phil. Mag. 2, 1079 (1952)) is discussed.

INTERMEDIATE-STATE REORIENTATION OF ORIENTED NUCLEI

1966 ◽  
Vol 44 (9) ◽  
pp. 1965-1984 ◽  
Author(s):  
J. M. Daniels ◽  
Sushil K. Misra
Keyword(s):  
Angular Distribution ◽  
Intermediate State ◽  
Low Temperatures ◽  
Nuclear Orientation ◽  
Zinc Nitrate ◽  
Magnesium Nitrate ◽  
Experimental Results ◽  
Γ Ray ◽  
Experimental Values ◽  
Reorientation Process

When radioactive nuclei in a paramagnetic ion at low temperatures become oriented (the magnetic h.f.s. method of nuclear orientation) and decay by β emission followed by a delayed γ ray, frequently, these nuclei become reoriented between the emission of the β ray and the γ ray, and this reorientation affects the observed angular distribution of the γ ray. The theory of this reorientation process is presented, assuming a time-independent Hamiltonian during the reorientation period. Numerical calculations of the effects to be expected on this static reorientation model have been made for 175Yb, 147Nd, and 141Ce in cerium magnesium nitrate, 57Co in cerium zinc nitrate, and 147Nd in neodymium ethyl sulphate. These calculations are compared with the reported experimental results. The experimental values for 147Nd in neodymium ethyl sulphate, 141Ce in cerium magnesium nitrate, and 57Co in cerium zinc nitrate could be explained by the static reorientation model; the others could not. The need is stressed for more reliable experimental results, in order to develop the theory of reorientation further.

Experiments on nuclear orientation at very low temperatures I, Establishment of a method of nuclear alinement and its application to cobalt-60

1954 ◽  
Vol 221 (1145) ◽  
pp. 170-188 ◽  
Keyword(s):  
Hyperfine Structure ◽  
Single Crystals ◽  
Magnetic Moment ◽  
Low Temperatures ◽  
Unknown Parameter ◽  
Nuclear Orientation ◽  
Magnetic Hyperfine ◽  
A Value ◽  
Adiabatic Demagnetization ◽  
Magnetic Hyperfine Structure

Experiments have been carried out which demonstrate the possibilities of the method of ‘magnetic hyperfine-structure alinement’ for the orientation of nuclei. Single crystals of composition (1% Co, 12% Cu, 87% Zn) Rb 2 (SO 4 ) 2 , 6H 2 O were cooled by adiabatic demagnetization to 0·01°K. The crystals contained a small quantity of radioactive 60 Co, which decays by β -emission followed by two γ -rays in cascade. The anisotropic distribution of the γ -rays from the oriented 60 Co nuclei was measured by an array of Geiger counters around the cryostat. The largest anisotropy observed was 33%, and the change in this anisotropy as the crystals warmed up to 1°K was fitted to theoretical curves where the only unknown parameter was the magnetic moment of 60 Co, for which a value of 3·5 ± 0·5 nuclear magnetons was deduced.

THE LOW-TEMPERATURE ORDERED STATE OF CERIUM MAGNESIUM NITRATE AND ITS INFLUENCE ON NUCLEAR ORIENTATION

1964 ◽  
Vol 42 (8) ◽  
pp. 1469-1480 ◽  
Author(s):  
J. M. Daniels ◽  
J. Felsteiner
Keyword(s):  
Magnetic Field ◽  
Nuclear Orientation ◽  
Dipole Interaction ◽  
Magnesium Nitrate ◽  
Divalent Ions ◽  
Antiferromagnetic Ordering ◽  
Γ Rays ◽  
Γ Ray ◽  
The Magnetic Field ◽  
Ordered State

The method of Luttinger and Tisza for minimizing the dipole–dipole interaction energy is applied to cerium magnesium nitrate, and an antiferromagnetic ordering of the cerium spins at 0 °K is found. Using this configuration, the magnetic field at the divalent ions is calculated. Next, the anisotropy of γ rays from Co60 aligned in this salt is calculated for temperatures below 0.003 °K. Qualitative agreement is found between these calculations and measurements of γ-ray anisotropy reported in the literature.

Nuclear magnetic resonance and magnetic structure of antiferromagnetic Mn2P2O7

1970 ◽  
Vol 48 (5) ◽  
pp. 521-530 ◽  
Author(s):  
Sung Ho Choh ◽  
C. V. Stager
Keyword(s):  
Experimental Data ◽  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
External Field ◽  
Hamiltonian Formalism ◽  
Single Crystal Sample ◽  
Spin Hamiltonian ◽  
Crystal Sample ◽  
Made In ◽  
Nuclear Magnetic

The nuclear magnetic resonance of 31P in antiferromagnetic Mn2P2O7 has been investigated at constant r.f. frequencies with the external field smaller than the spin-flop field. Resonance measurements were made in a single crystal sample at liquid helium temperatures. Experimental data, including the angular dependence, the external field dependence, and the temperature dependence of the resonances, are satisfactorily explained by the spin Hamiltonian formalism for NMR in antiferromagnets, proposed by the authors. NMR results confirm the spin direction obtained from susceptibility measurements, and establish the magnetic space group as C2c2.

Single crystal neutron diffraction studies of antiferromagnets at low temperatures in applied magnetic fields

1959 ◽  
Vol 20 (2-3) ◽  
pp. 180-184 ◽  
Author(s):  
W.C. Koehler ◽  
M. K. Wilkinson ◽  
J.W. Cable ◽  
E.O. Wollan
Keyword(s):  
Magnetic Fields ◽  
Neutron Diffraction ◽  
Single Crystal ◽  
Low Temperatures

scholarly journals Kondo effect and superconductivity in niobium with iron impurities

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Hansong Zeng ◽  
Dan Zhou ◽  
Guoqing Liang ◽  
Rujun Tang ◽  
Zhi H. Hang ◽  
...  
Keyword(s):  
Magnetic Moment ◽  
Low Temperatures ◽  
Kondo Effect ◽  
Film Structure ◽  
Kondo Temperature ◽  
Superconducting Transition ◽  
Interesting Phenomenon ◽  
Superconducting Device ◽  
Bcc Lattice ◽  
Device Applications

AbstractKondo effect is an interesting phenomenon in quantum many-body physics. Niobium (Nb) is a conventional superconductor important for many superconducting device applications. It was long thought that the Kondo effect cannot be observed in Nb because the magnetic moment of a magnetic impurity, e.g. iron (Fe), would have been quenched in Nb. Here we report an observation of the Kondo effect in a Nb thin film structure. We found that by co-annealing Nb films with Fe in Argon gas at above 400 $$^{\circ }$$ ∘ C for an hour, one can induce a Kondo effect in Nb. The Kondo effect is more pronounced at higher annealing temperature. The temperature dependence of the resistance suggests existence of remnant superconductivity at low temperatures even though the system never becomes superconducting. We find that the Hamann theory for the Kondo resistivity gives a satisfactory fitting to the result. The Hamann analysis gives a Kondo temperature for this Nb–Fe system at $$\sim $$ ∼ 16 K, well above the superconducting transition onset temperature 9 K of the starting Nb film, suggesting that the screening of the impurity spins is effective to allow Cooper pairs to form at low temperatures. We suggest that the mechanism by which the Fe impurities retain partially their magnetic moment is that they are located at the grain boundaries, not fully dissolved into the bcc lattice of Nb.

scholarly journals Physics and modes of star cluster formation

2009 ◽  
Vol 5 (S266) ◽  
pp. 29-34
Author(s):  
Matthew R. Bate
Keyword(s):  
Radiative Transfer ◽  
Magnetic Fields ◽  
Cluster Formation ◽  
Star Cluster ◽  
Hydrodynamical Simulations ◽  
Made In

AbstractI review the progress made in understanding the physics and modes of star cluster formation through the use of direct self-gravitating hydrodynamical simulations, including those that have recently been performed incorporating radiative transfer and magnetic fields.

Measurements of magnetic resonance and high-frequency conductivity at low temperatures and high magnetic fields

1999 ◽  
Author(s):  
J. M. Schrama ◽  
Eva J. Rzepniewski ◽  
Arzhang Ardavan ◽  
R. Edwards ◽  
A.-K. Klehe ◽  
...  
Keyword(s):  
Magnetic Resonance ◽  
Magnetic Fields ◽  
High Frequency ◽  
Low Temperatures ◽  
High Magnetic Fields

Pressure measurements with a precision of 0.001 ppm in magnetic fields at low temperatures

1993 ◽  
Vol 64 (11) ◽  
pp. 3215-3218 ◽  
Author(s):  
Y. Miura ◽  
N. Matsushima ◽  
T. Ando ◽  
S. Kuno ◽  
S. Inoue ◽  
...  
Keyword(s):  
Magnetic Fields ◽  
Low Temperatures ◽  
Pressure Measurements

scholarly journals Dictionnaire de la nomenclature des objets celestes

1982 ◽  
Vol 64 ◽  
pp. 203-205
Author(s):  
A. Fernandez ◽  
M.C. Lortet ◽  
F. Spite
Keyword(s):  
Data Centers ◽  
Astronomical Data ◽  
The Future ◽  
Future Publication ◽  
Γ Ray ◽  
Made In

AbstractThe confusing situation of the nomenclature of the astronomical objects led us to build, as a first step, a dictionary of the designations presently used. The future publication of this work is supported by Commission 5 of IAU. A brief description of this dictionary, as well as a sample of it, is given here. The designations (acronyms) will be given, together with the format, the total number of objects, the type of objects, the code for the complete bibliographical reference, the signification of acronym… Nomenclature for X and γ-ray sources, designations by constellations and descriptive designations will be dealt with as well. Good compilations are a considerable help in nomenclature problems; every effort should be made in order of : 1) urging specialists to build compilations 2) announce compilations in progress to Astronomical Data Centers and to the present authors.

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