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.

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.

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.

Study of the 1459-keV level in 19F by the 19F(p,p′γ)19F reaction

1970 ◽  
Vol 48 (7) ◽  
pp. 827-833 ◽  
Author(s):  
S. T. Lam ◽  
A. E. Litherland ◽  
J. J. Simpson
Keyword(s):  
Angular Distribution ◽  
Single Crystal ◽  
Linear Polarization ◽  
Proton Energy ◽  
Branching Ratios ◽  
Mixing Ratio ◽  
Γ Ray ◽  
Good Agreement

The 1459-keV level of 19F was populated by the 19F(p,p′γ)19F reaction at a proton energy of 2.78 MeV. The E2/M1 mixing ratio for the 1459 → 110 keV transition was determined to be [Formula: see text] from a combination of the γ-ray angular distribution and linear polarization and the nuclear lifetime. The γ-ray angular distribution was measured with a coaxial Ge(Li) detector and the γ-ray linear polarization with a planar Ge(Li) detector. The corresponding E2 and M1 transition strengths for a lifetime of 0.084 ± 0.020 ps are found to be [Formula: see text] and 0.10 ± 0.03 W.u. respectively. They are in good agreement with the particle–hole calculations of Benson and Flowers. The branching ratios of the 1459-keV level agree well with those of Poletti et al. The γ-ray transitions from the 1459-keV level provide a good example for demonstrating the usefulness of a single crystal Ge(Li) polarimeter.

ALPHA DECAY AND FISSION OF ALIGNED NUCLEI

1960 ◽  
Vol 38 (2) ◽  
pp. 290-314 ◽  
Author(s):  
N. R. Steenberg ◽  
R. C. Sharma
Keyword(s):  
Angular Distribution ◽  
High Temperature ◽  
Experimental Work ◽  
Low Temperatures ◽  
Alpha Decay ◽  
Alpha Particles ◽  
Nuclear Shape ◽  
Fission Fragments ◽  
Partial Waves ◽  
High Temperature Approximation

The theory of the angular distribution of alpha particles and of fission fragments from nuclei aligned at low temperatures is presented. Very explicit results are obtained in the high temperature approximation. These are directly dependent upon the branching which takes place to the various allowed partial waves. This branching is influenced by the nuclear shape, but it is shown that for this problem the effect of penetrating a spheroidal barrier is not critical. An application is made to the experimental work so far available and the result is reasonably satisfactory.

scholarly journals The Investigation of Effects of Temperature and Nanoparticles Volume Fraction on the Viscosity of Copper Oxide-ethylene Glycol Nanofluids

2017 ◽  
Author(s):  
Mohammad Hemmat Esfe
Keyword(s):  
Ethylene Glycol ◽  
Copper Oxide ◽  
Volume Fraction ◽  
Relative Viscosity ◽  
Experimental Results ◽  
Different Temperatures ◽  
Nanoparticles Volume Fraction ◽  
Effects Of Temperature ◽  
Nanofluid Viscosity ◽  
Experimental Values

In the present article, the effects of temperature and nanoparticles volume fraction on the viscosity of copper oxide-ethylene glycol nanofluid have been investigated experimentally. The experiments have been conducted in volume fractions of 0 to 1.5 % and temperatures from 27.5 to 50 °C. The shear stress computed by experimental values of viscosity and shear rate for volume fraction of 1% and in different temperatures show that this nanofluid has Newtonian behaviour. The experimental results reveal that in a given volume fraction when temperature increases, viscosity decreases, but relative viscosity varies. Also, in a specific temperature, nanofluid viscosity and relative viscosity increase when volume fraction increases. The maximum amount of increase in relative viscosity is 82.46% that occurs in volume fraction of 1.5% and temperature of 50 °C. Some models of computing nanofluid viscosity have been suggested. The greatest difference between the results obtained from these models and experimental results was down of 4 percent that shows that there is a very good agreement between experimental results and the results obtained from these models.

Interaction Between Low Temperatures Spacers and Source Drain Extensions and Pockets for Both NMOS and PMOS of the 65 nm Node Technology

2006 ◽  
Vol 912 ◽  
Author(s):  
Nathalie Cagnat ◽  
Cyrille Laviron ◽  
Daniel Mathiot ◽  
Pierre Morin ◽  
Frédéric Salvetti ◽  
...  
Keyword(s):  
Oxide Layer ◽  
Hydrogen Content ◽  
Low Temperatures ◽  
Direct Contact ◽  
Fabrication Process ◽  
Experimental Results ◽  
The Other ◽  
Mos Transistors ◽  
Phosphorus Source ◽  
Activation Annealing

AbstractDuring the MOS transistors fabrication process, the source-drain extension areas are directly in contact with the oxide liner of the spacers stack. In previous works [1, 2, 3] it has been established that boron can diffuse from the source-drain extensions into the spacer oxide liner during the subsequent annealing steps, and that the amount of boron loss depends on the hydrogen content in the oxide, because it enhances B diffusivity in SiO2.In order to characterize and quantify the above phenomena, we performed test experiments on full sheet samples, which mimic either BF2 source-drain extensions over arsenic pockets implants, or BF2 pockets under arsenic or phosphorus source-drain extensions implants. Following the corresponding implants, the wafers were covered with different spacer stacks (oxide + nitride) deposited either by LPCVD, or PECVD. After appropriate activation annealing steps, SIMS measurements were used to characterize the profiles of the various dopants, and the corresponding dose loss was evaluated for each species.Our experimental results clearly evidence that LPCVD or PECVD spacer stacks have no influence on the arsenic profiles. On the other hand, phosphorus and boron profiles are affected. For boron profiles, each spacer type has a different influence. It is also shown that boron out-diffuses not only from the B doped source-drain extension in direct contact with the oxide layer, but also from the "buried" B pockets lying under n-doped source drain extension areas. All these results are discussed in term of the possible relevant mechanism.

THE EFFECT OF INTERACTIONS ON THE ANGULAR DISTRIBUTION OF γ-RAYS FROM AN ASSEMBLY OF ORIENTED NUCLEI

1957 ◽  
Vol 35 (9) ◽  
pp. 1133-1145 ◽  
Author(s):  
J. M. Daniels
Keyword(s):  
Angular Distribution ◽  
Energy State ◽  
Nuclear Orientation ◽  
Γ Radiation ◽  
Orientation Experiment ◽  
High Temperature Approximation ◽  
Γ Rays ◽  
Matrix Formula ◽  
Paramagnetic Ions ◽  
Radioactive Ions

The angular distribution of γ-radiation from an assembly of nuclei oriented by the magnetic h.f.s. method can be very much modified by interactions between the radioactive ions and other paramagnetic ions in the crystal. In order to calculate the effect of these interactions, an operator Γ is derived which represents the angular distribution of γ-rays from a radioactive nucleus. The angular distribution at any temperature is given by Spur(Γρ), where ρ is the statistical matrix [Formula: see text], [Formula: see text] being the Hamiltonian for the whole crystal. For a high temperature approximation, ρ is expanded in powers of 1/T. It is found that, for alignment by the magnetic h.f.s. method, the first term which contains interaction parameters is that in 1/T4, and an expression is given for the contribution of interactions to this term.At very low temperatures, perturbation theory is used to estimate the effect of interactions on the lowest nuclear energy state, and hence on the angular distribution of γ-rays. It is found that, if an external magnetic field is applied along a principal axis of the g-tensor of the radioactive ions, interactions have no influence on the angular distribution of γ-rays in the limit of large fields. It is also shown that Bleaney's restriction, that for a successful nuclear orientation experiment the broadening of the levels should be less than the hyperfine splitting, is not necessary in this case.

scholarly journals Quantum Calculations to Estimate the Heat of Hydrogenation Theoretically

2020 ◽  
Author(s):  
Ali Amir Khairbek
Keyword(s):  
Unsaturated Hydrocarbon ◽  
Experimental Results ◽  
Basis Set ◽  
Good Linear ◽  
Complete Basis ◽  
Complete Basis Set ◽  
Complete Basis Set Limit ◽  
The Mean ◽  
Experimental Values ◽  
Linear Correlations

Standard enthalpies of hydrogenation of 29 unsaturated hydrocarbon compounds were calculated in the gas phase by CCSD(T) theory with complete basis set cc-pVXZ, where X = DZ, TZ, as well as by complete basis set limit extrapolation. Geometries of reactants and products were optimized at the M06-2X/6-31g(d) level. This M06-2X geometries were used in the CCSD(T)/cc-pVXZ//M06-2X/6-31g(d) and cc-pV(DT)Z extrapolation calculations. (MAD) the mean absolute deviations of the enthalpies of hydrogenation between the calculated and experimental results that range from 8.8 to 3.4 kJ mol−1 based on the Comparison between the calculation at CCSD(T) and experimental results. The MAD value has improved and decreased to 1.5 kJ mol−1 after using complete basis set limit extrapolation. The deviations of the experimental values are located inside the “chemical accuracy” (±1 kcal mol−1 ≈ ±4.2 kJ mol−1) as some results showed. A very good linear correlations between experimental and calculated enthalpies of hydro-genation have been obtained at CCSD(T)/cc-pVTZ//M06-2X/6-31g(d) level and CCSD(T)/cc-pV(DT)Z extrapolation levels (SD =2.11 and 2.12 kJ mol−1, respectively).

scholarly journals Focusing effect of bent GaAs crystals for γ-ray Laue lenses: Monte Carlo and experimental results

2015 ◽  
Vol 41 (1-2) ◽  
pp. 307-326 ◽  
Author(s):  
E. Virgilli ◽  
F. Frontera ◽  
P. Rosati ◽  
E. Bonnini ◽  
E. Buffagni ◽  
...  
Keyword(s):  
Monte Carlo ◽  
Experimental Results ◽  
Focusing Effect ◽  
Γ Ray
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