RADIATION CHEMISTRY OF CYCLOHEXANE: I. ISOTOPIC COMPOSITION OF HYDROGEN EVOLVED FROM MIXTURES OF C6D12 AND C6H12

1960 ◽  
Vol 38 (4) ◽  
pp. 539-543 ◽  
Author(s):  
P. J. Dyne ◽  
W. M. Jenkinson
Keyword(s):  
Isotopic Composition ◽  
Radiation Chemistry ◽  
A Value ◽  
Γ Ray

The yield of D2 formed by a unimolecular process in the γ-ray irradiation of cyclohexane-d12 has been deduced from the isotopic composition of hydrogen evolved from C6H12–C6D12 mixtures. A value of 0.25 molecule/100 ev is found for this "molecular" yield. This yield is only slightly reduced by iodine but is considerably reduced in the presence of biphenyl.

THE IDENTIFICATION AND HALF LIVES OF FISSION-PRODUCT Rb92 AND Rb93

1960 ◽  
Vol 38 (12) ◽  
pp. 1614-1622 ◽  
Author(s):  
K. Fritze ◽  
T. J. Kennett
Keyword(s):  
Fission Product ◽  
Decay Rate ◽  
Half Life ◽  
Fission Products ◽  
Strontium Isotopes ◽  
A Value ◽  
Γ Ray ◽  
Rubidium Isotopes

The existence of two new rubidium isotopes, Rb92 and Rb93, has been established and their half lives measured. The half lives of these short-lived fission products were determined using a technique of timed precipitations. The values obtained for Rb92 and Rb93 were 5.3 ± 0.5 sec and 5.6 ± 0.5 sec respectively. The half lives of the strontium and yttrium daughters were also determined. The strontium isotopes were studied by observing the decay rate of a characteristic γ-ray peak. For Sr92, the decay of the 1.37-Mev line gave a value of 2.71 ± 0.02 hr. A γ-ray peak at 590 kev, which was found to be associated with Sr93, decayed with a half life of 7.54 ± 0.06 min. The half lives of the yttrium daughters were determined by β counting. The values found for Y92 and Y93 were 3.53 ± 0.02 hr and 10.1 ± 0.1 hr respectively.

RADIATION CHEMISTRY OF CYCLOHEXANE: III. EFFECT OF BENZENE AND IODINE ON THE ISOTOPIC COMPOSITION OF RADIOLYTIC HYDROGEN FROM C6D12–C6H12 MIXTURES

1961 ◽  
Vol 39 (11) ◽  
pp. 2163-2170 ◽  
Author(s):  
P. J. Dyne ◽  
W. M. Jenkinson
Keyword(s):  
Isotopic Composition ◽  
Radiation Chemistry ◽  
Bimolecular Reaction ◽  
Specific Yield ◽  
Unimolecular Decomposition ◽  
Common Precursor

The isotopic composition of hydrogen evolved in the radiolysis of C6D12–C6H12 mixtures has been measured in the presence of various amounts of benzene and iodine. The yield of the unimolecular decomposition and the specific yield of the bimolecular reaction are reduced in approximately the same proportion as the yield of total hydrogen. It is concluded that (i) iodine and benzene interact to a comparable extent with both unimolecular and bimolecular decomposition modes, (ii) it is probable that neither of these additives act by scavenging, and (iii) it is probable that they act by quenching a common precursor of the two decomposition modes.

K-shell autoionization in the beta decay of 95Nb

1976 ◽  
Vol 54 (20) ◽  
pp. 2024-2027 ◽  
Author(s):  
M. Jurčević ◽  
A. Ljubičić ◽  
Z. Krečak ◽  
K. Ilakovac
Keyword(s):  
Theoretical Result ◽  
Beta Decay ◽  
Coincidence Method ◽  
X Ray ◽  
A Value ◽  
Γ Ray ◽  
Recent Theoretical Result

The X-ray–γ-ray coincidence method was applied to determine the probability of K-shell autoionization in the beta decay of 95Nb. A value of PK = (3.4 ± 0.4) × 10−4 was obtained. This result is in agreement with the recent theoretical result obtained by Law and Campbell.

THE TOTAL INTERNAL CONVERSION COEFFICIENT OF THE 279-kev TRANSITION FOLLOWING THE DECAY OF Hg203 AS MEASURED BY A NEW COINCIDENCE METHOD

1962 ◽  
Vol 40 (4) ◽  
pp. 383-392 ◽  
Author(s):  
J. G. V. Taylor
Keyword(s):  
Standard Deviation ◽  
Internal Conversion ◽  
Conversion Coefficient ◽  
Internal Conversion Coefficient ◽  
Coincidence Method ◽  
Β Decay ◽  
A Value ◽  
Conversion Coefficients ◽  
Γ Ray ◽  
Total Conversion Coefficient

Using a new coincidence method, the total internal conversion coefficient for the 279-kev transition following the β-decay of Hg203 has been measured with a standard deviation of about 1%. The method which employs a 4πβ–γ coincidence arrangement is based on the differential absorption of β-particles and conversion electrons in 4π geometry. For determining the absolute efficiencies of γ-ray spectrometers or ion-chambers, the method has the advantage of yielding directly the number of γ-ray quanta emitted per Hg203 disintegration without requiring any knowledge of the K:L:M conversion ratios. Likely sources of systematic error have been investigated and their effect has been shown to be smaller than the quoted standard deviation. The value obtained is α = 0.2262 ±.0019 or γ/β = 0.8155 ±.0015, in excellent agreement with the recent β-ray spectrometer measurements of Nijgh et al. This is of interest because a number of widely differing values of conversion coefficients for this transition have been reported. If the K/(L+M+N) conversion ratio of 2.60 ±.06 found by Nijgh et al. is combined with our total conversion coefficient, a value αK = 0.1633 ±.0017 is obtained.

scholarly journals The rate of emission of alpha particles from radium

1928 ◽  
Vol 121 (787) ◽  
pp. 367-380 ◽  
Keyword(s):  
Heat Evolution ◽  
Alpha Particles ◽  
The Other ◽  
Decomposition Products ◽  
A Value ◽  
Considerable Portion ◽  
Γ Ray ◽  
Recoil Atoms ◽  
Energy Relations ◽  
Α Particles

A knowledge of the number, Z, of α particles disintegrations taking place in unit mass of radium in unit time is of considerable importance in the interpretation of radioactive changes, and, in particular, of the energy relations involved. The heat evolution of radium and its short-lived decomposition products has been studied by a number of workers. Most of the heat production is accounted for by the energy of the a particles and recoil atoms, and in any particular experiment an allowance may be made for the β and γ ray energy absorbed. The experimental results are in agreement with the energy calculated from the number and energy of the a particles if a value is assumed for Z of about 3.7 . 10 10 . If, on the other hand, the value 3.57.10 10 obtained by Rutherford and Geiger, or the value 3.40.1010 recently published by Geiger and Werner, be taken, the calculation leaves a considerable portion of the heating effect unaccounted for, and this would involve an unidentified heatproducing mechanism in the disintegration.

THE γ-RAYS OF THORIUM CC′

1948 ◽  
Vol 26a (5) ◽  
pp. 313-325 ◽  
Author(s):  
S. C. Fultz ◽  
G. N. Harding
Keyword(s):  
Energy Level ◽  
Long Range ◽  
Level Scheme ◽  
Electric Quadrupole ◽  
Coincidence Rate ◽  
A Value ◽  
Γ Rays ◽  
Γ Ray ◽  
Particle Group ◽  
Α Particles

At least two energy level schemes have been proposed for the ThC′ nucleus, which is excited in the β-disintegration ThCC′. That of Ellis (1933) includes three γ-rays of energies 0.726, 1.62, and 1.80 Mev., the 1.62 Mev. ray being doubtful. The level scheme of Latyschev and Kulchitsky (1940) has eight γ-rays including one of energy 2.2 Mev., for which no corresponding long-range α-particle group has been observed. The two level schemes lead to widely differing values for the total γ-ray energy of ThCC′. In the present investigation a value for the total γ-ray energy of ThCC′ has been obtained by measuring coincidences between the γ-rays of ThCC′ and the subsequently emitted α-particles of ThC′. It is shown that this value (0.14 Mev.) favors the level scheme of Ellis, including only the γ-rays of energy 0.726 and 1.80 Mev., and taking the former as electric quadrupole. It was found that under certain conditions the external bremsstrahlung excited by the β-rays of ThCC′ in the source-holder contributed appreciably to the coincidence rate. Precautions were taken to minimize this effect.

The Density at 25 °C of D2O with Natural Oxygen Isotopic Composition

1975 ◽  
Vol 30 (1) ◽  
pp. 103-106
Author(s):  
T. Babeliowsky ◽  
J. Brulmans
Keyword(s):  
Isotopic Composition ◽  
Heavy Water ◽  
Hydrogen Content ◽  
Oxygen Isotopic Composition ◽  
A Value ◽  
Oxygen Isotopic

Abstract In measuring the influence of oxygen isotopic composition and of hydrogen content on the density of heavy water an extrapolation was made to 100% D2O with natural oxygen isotopic composition, starting with the density of a highly enriched heavy water (99.95% D2O, about natural oxygen isotopic composition).A value of 1104.481 kg/m 3 at 25 °C was obtained.

scholarly journals Variation of lead isotopic composition and atomic weight in terrestrial materials (IUPAC Technical Report)

2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Xiang-Kun Zhu ◽  
Jacqueline Benefield ◽  
Tyler B. Coplen ◽  
Zhaofu Gao ◽  
Norman E. Holden
Keyword(s):  
Isotopic Composition ◽  
Radioactive Decay ◽  
Isotope Ratios ◽  
Atomic Weight ◽  
High Grade ◽  
A Value ◽  
Metamorphic Terrain ◽  
Phosphate Mineral ◽  
Technical Report ◽  
North Western

AbstractThe isotopic composition and atomic weight of lead are variable in terrestrial materials because its three heaviest stable isotopes are stable end-products of the radioactive decay of uranium (238U to 206Pb; 235U to 207Pb) and thorium (232Th to 208Pb). The lightest stable isotope, 204Pb, is primordial. These variations in isotope ratios and atomic weights provide useful information in many areas of science, including geochronology, archaeology, environmental studies, and forensic science. While elemental lead can serve as an abundant and homogeneous isotopic reference, deviations from the isotope ratios in other lead occurrences limit the accuracy with which a standard atomic weight can be given for lead. In a comprehensive review of several hundred publications and analyses of more than 8000 samples, published isotope data indicate that the lowest reported lead atomic weight of a normal terrestrial materials is 206.1462 ± 0.0028 (k = 2), determined for a growth of the phosphate mineral monazite around a garnet relic from an Archean high-grade metamorphic terrain in north-western Scotland, which contains mostly 206Pb and almost no 204Pb. The highest published lead atomic weight is 207.9351 ± 0.0005 (k = 2) for monazite from a micro-inclusion in a garnet relic, also from a high-grade metamorphic terrain in north-western Scotland, which contains almost pure radiogenic 208Pb. When expressed as an interval, the lead atomic weight is [206.14, 207.94]. It is proposed that a value of 207.2 be adopted for the single lead atomic-weight value for education, commerce, and industry, corresponding to previously published conventional atomic-weight values.

Observations of the Thermal Decomposition of Brucite

1968 ◽  
Vol 26 ◽  
pp. 446-447
Author(s):  
P. L. Burnett ◽  
W. R. Mitchell ◽  
C. L. Houck
Keyword(s):  
Thermal Decomposition ◽  
Magnesium Oxide ◽  
Basal Plane ◽  
Magnesium Ions ◽  
A Value ◽  
Reaction Proceeds

Natural Brucite (Mg(OH)2) decomposes on heating to form magnesium oxide (MgO) having its cubic ﹛110﹜ and ﹛111﹜ planes respectively parallel to the prism and basal planes of the hexagonal brucite lattice. Although the crystal-lographic relation between the parent brucite crystal and the resulting mag-nesium oxide crystallites is well known, the exact mechanism by which the reaction proceeds is still a matter of controversy. Goodman described the decomposition as an initial shrinkage in the brucite basal plane allowing magnesium ions to shift their original sites to the required magnesium oxide positions followed by a collapse of the planes along the original <0001> direction of the brucite crystal. He noted that the (110) diffraction spots of brucite immediately shifted to the positions required for the (220) reflections of magnesium oxide. Gordon observed separate diffraction spots for the (110) brucite and (220) magnesium oxide planes. The positions of the (110) and (100) brucite never changed but only diminished in intensity while the (220) planes of magnesium shifted from a value larger than the listed ASTM d spacing to the predicted value as the decomposition progressed.

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