Nuclear polarization of cobalt<i>60</i>

Ambler, E.; Grace, M. A.; Halban, H.; Kürti, N.; Durand, H.; Johnson, C.E.; Lemmer, H.R.

doi:10.1080/14786440208520296

Cited by 43 publications

(7 citation statements)

References 5 publications

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“…2 Previous to these reports Oberly and Burstein, 3 and Briggs 4 have observed an absorption band in high-resistivity silicon at 8.9 microns and ascribed it to the lattice. Subsequently Fan and Becker 5 had shown that this band is in fact characteristic of the silicon lattice, being present in the same strength in all samples.…”

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confidence: 97%

Infrared Lattice Absorption Bands in Germanium, Silicon, and Diamond

Collins¹,

Fan²

1954

Phys. Rev.

201

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Infrared absorption bands characteristic of the crystal lattice were investigated for germanium and silicon. The absorption was found to be insensitive to lattice imperfections due to impurities (^40 18 cm -3 ) and due to disorders (^10 19 cm -3 ) produced by nucleon irradiation. It did vary with temperature in the same way as the calculated mean-square displacement of the atoms. Variations of absorption with temperature were also studied for two specimens of type I diamond. The bands characteristic of type II diamonds showed similar temperature dependence, whereas the long-wavelength bands were temperature insensitive. It appears that the observed absorption in germanium and silicon corresponds to the absorption characteristic of type II diamond and is made possible by the thermal vibration of the atoms. The long-wavelength bands in type I diamonds may be due to impurities.

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confidence: 97%

Infrared Lattice Absorption Bands in Germanium, Silicon, and Diamond

Collins¹,

Fan²

1954

Phys. Rev.

201

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“…Early in this work serious discrepancies were observed between the observed and calculated y-ray polar diagrams (Ambler et al 1953;Grace et al 1954). The most striking effect of this type ) was observed in the emission of y-rays from Mn54 included as an impurity in Ce2Mg3(N03)1?.24H20, where the observed anisotropy of y-radiation was much lower than predicted, and actually decreased as the temperature fell below 0.003" I<., the Curie temperature of the salt.…”

Section: Introductionmentioning

confidence: 90%

The EFFECT OF INTERACTIONS ON THE ANGULAR DISTRIBUTION OF Γ-Rays FROM AN ASSEMBLY OF ORIENTED NUCLEI

Daniels¹

1957

Can. J. Phys.

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The angular distribution of yradiation fro111 an asse~nbly of nuclei oriented by the magnetic h.f.s. method can be very much modified by interactio~ls between the radioactive ions and other paramagnetic ions in the crystal. In order to calculate the effect of these interactions, an operator r is derived which represents the angular distribution of 7-rays frorn a radioactive nucleus. The angular distribution a t any temperature is given by Spur(rp), where p is the statistical rnatrix e x p ( -@ / k~) / S~u r [ e x~( -@ / k~) ] , @ being the Harniltonian for the whole crystal. For a high temperature approximation, p is expanded in powers of 1/T. I t is found that, for align~nent by the magnetic 11.f.s. method, the first term which contains interaction parameters is that in 1/T', and an expression is given for the contribution of interactio~ls 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 7-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 7-rays in the limit of large fields. I t 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.'Manuscript

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“…It was assumed that X, the decay constant of Mn 56 and the times U and tf were known with negligible error. The expression (5) can then be written Zi=Axi+Byi, (6) in which Zi, x i7 and ji are measured quantities. For a typical activation, the number of g/s or the number of intervals, n, for each of which a total count was taken, was about ten.…”

Section: Zi=^[exp(-xo-exp(~x^*)]+j5(/ T --^*) (5)mentioning

confidence: 99%

“…(The angular distribution of gamma rays from such polarized samples containing radioactive nuclei has been observed. 6 An experiment in which neutron effects of nuclear polarization in gadolinium sulfate were observed, has been mentioned briefly, 7 but no details of the experiment have been reported. )…”

Section: Introductionmentioning

confidence: 99%

Interaction of Polarized Neutrons with PolarizedMn55Nuclei

et al. 1954

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The dependence of the capture cross section of polarized Mn 65 nuclei for polarized neutrons upon relative orientations of incident and bombarded particles has been directly observed. The target material was the paramagnetic substance, manganous ammonium sulfate, which is known to have a large hyperfine structure coupling. It was placed in a magnetic field of 2350 oersteds at a temperature of 0.20°K. Under these conditions the polarization of the paramagnetic electrons is about 85 percent. Because of the large effective magnetic field created by the paramagnetic electrons at the Mn nucleus, the nuclei should achieve a polarization of 16 percent. The 2.6-hour activity of the residual nucleus, Mn 56 , was measured after the sample had been bombarded with a beam of slow neutrons polarized to the extent of 32 percent by passage through magnetized iron. The activity for neutron polarizing field and sample polarizing field parallel was found to be 3.4 percent less than for the fields antiparallel. The difference in the two activities was found to depend upon the sample temperature in accordance with theory. The difference was found to be unaccompanied by a corresponding change in sample transmission. These results are interpreted to mean 1hat the change in sample activity was due to the dependence of the capture cross section of the polarized Mn nuclei upon the relative orientation of the interacting particles. The observations are discussed in terms of available information about the energy level system of the compound nucleus, Mn 56 .

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Nuclear polarization of cobalt60

Cited by 43 publications

References 5 publications

Infrared Lattice Absorption Bands in Germanium, Silicon, and Diamond

Infrared Lattice Absorption Bands in Germanium, Silicon, and Diamond

The EFFECT OF INTERACTIONS ON THE ANGULAR DISTRIBUTION OF Γ-Rays FROM AN ASSEMBLY OF ORIENTED NUCLEI

Interaction of Polarized Neutrons with PolarizedMn55Nuclei

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