The half life of 239Pu: By specific activity measurements and by mass spectronetric determination of daughter growth

32Si dating of glacier ice has hitherto been complicated by the poor knowledge of the half life. Furthermore, fall-out of bomb-produced 32Si impedes the determination of the specific activity of cosmic-ray produced 32Si in recent precipitation. Measurements on well-dated pre-bomb samples from the Greenland ice sheet establish a calibration for 32Si dating of up to 1 000 year old polar ice samples of the magnitude of 1 metric ton. If the technique is used on temperate glaciers, samples of pre-bomb deposits (or from after 1970) must be collected for comparison with samples of old ice, using an apparent half life of 295±25 years. Due to secular cosmic-ray flux variations, the true half life of 32Si is estimated at the slightly higher value of 330±40 years.

Download Full-text

Determination of the specific ?-activity and the half-life of U233

Atomic Energy ◽

10.1007/bf01471929 ◽

1960 ◽

Vol 6 (1) ◽

pp. 41-41

Author(s):

Ya. P. Dokuchaev ◽

I. S. Osipov

Keyword(s):

Half Life ◽

Specific Activity

Download Full-text

Half-Life Determination of 41Ca and Some Other Radioisotopes

Radiocarbon ◽

10.1017/s0033822200063669 ◽

1992 ◽

Vol 34 (3) ◽

pp. 436-446 ◽

Cited By ~ 8

Author(s):

Walter Kutschera ◽

Irshad Ahmad ◽

Michael Paul

Keyword(s):

Mass Spectrometry ◽

Electron Capture ◽

Half Life ◽

Specific Activity ◽

Low Energy ◽

X Rays ◽

Weighted Mean ◽

Electron Capture Decay

We have performed a new determination of the half-life of 41Ca by measuring the specific activity of an enriched Ca material with known 41Ca abundance. We measured the activity via the 3.3-keV X-rays emitted in the electron capture decay of 41Ca, and the 41Ca abundance was measured by low-energy mass spectrometry. The result, t1/2 = (1.01 ± 0.10) × 105 yr, agrees with the recent ‘geological’ half-life of Klein et al., (1991), t1/2 = (1.03 ± 0.07) × 105 yr, and with the corrected value of Mabuchi et al. (1974), t1/2 = (1.13 ± 0.12) × 105 yr. We recommend the weighted mean of these three measurements, t1/2 = (1.04 ± 0.05) × 105 yr, as the most probable half-life of 41Ca. We also discuss the situation of the radioisotopes, 32Si, 44Ti, 79Se and 126Sn, whose half-lives, though still uncertain, are potentially interesting for future AMS studies and other applications.

Download Full-text

The half life of plutonium-240 determined by specific-activity measurements

The International Journal of Applied Radiation and Isotopes ◽

10.1016/0020-708x(84)90228-x ◽

1984 ◽

Vol 35 (3) ◽

pp. 171-172 ◽

Cited By ~ 7

Author(s):

Frederick J. Steinkruger ◽

George M. Matlack ◽

Richard J. Beckman

Keyword(s):

Half Life ◽

Specific Activity ◽

Activity Measurements

Download Full-text

Improvements in the determination of the turnover rate of plasma thyroxine in avian species: application to the Japanese quail

Journal of Endocrinology ◽

10.1677/joe.0.1140191 ◽

1987 ◽

Vol 114 (2) ◽

pp. 191-198 ◽

Cited By ~ 2

Author(s):

E. J. Cookson ◽

J. Glover

Keyword(s):

Japanese Quail ◽

Half Life ◽

Turnover Rate ◽

Specific Activity ◽

Simple Procedure ◽

High Specific Activity ◽

Future Application ◽

Sodium Thiocyanate ◽

Plasma Samples

ABSTRACT The disappearance of the thyroid hormone thyroxine (T4) from plasma in fully grown male Japanese quail can be described as a first order process with a rate constant of 0·178 ± 0·013/h (mean±s.e.m., n = 8), which represents a half-life of 3·90 h. A small amount of [125I]T4 in relation to total circulating T4 was injected i.v. into Japanese quail and plasma samples were taken at appropriate time-intervals for the determination of residual plasma radioactivity. The rate of disappearance of [125I]T4 was subsequently equated to the turnover rate of the endogenous hormone. Previous methods were modified to overcome problems arising from possible disturbance of plasma T4 metabolism, recirculation of radiolabelled iodide, and to purify the [125I]T4 from the plasma samples. By using labelled T4 of very high specific activity, the amount of [125I]T4 administered was kept much smaller than has been used in previous studies on Japanese quail, thus limiting any interference with plasma T4 dynamics. To minimize any disturbance of plasma T4 metabolism, only four blood samples were taken, at three-hourly intervals after the injection of [125I]T4. The rapid turnover of T4 produced a large amount of labelled inorganic iodide, the re-entry of which into the plasma T4 pool was inhibited by s.c. administration of sodium thiocyanate 1 h before injection of[125I]T4. Assay of the true [125I]T4 turnover was significantly improved over that used in previous studies by purifying the [125I]T4 from the plasma samples chromatographically. The samples were applied to small Sephadex G-25 columns with sodium hydroxide (0·1 mol/l) as the eluant. This simple procedure clearly separated the [125I]T4 from the other radioiodinated plasma components such as free iodide, non-hormonal iodinated proteins and triiodothyronine (T3), thus enabling a more accurate assessment of the residual labelled T4 concentration in the plasma and hence the T4 half-life. The future application of this method to the study of plasma T4 turnover under various experimental conditions is discussed and the possible involvement of T4 turnover studies in the assessment of T4 to T3 conversion is considered. J. Endocr. (1987) 114, 191–198

Download Full-text

Absolute and relative measurement of the 243Am half-life

Journal of Radioanalytical and Nuclear Chemistry ◽

10.1007/s10967-020-07450-9 ◽

2020 ◽

Vol 326 (3) ◽

pp. 1785-1793 ◽

Cited By ~ 1

Author(s):

M. Marouli ◽

S. Pommé ◽

V. Jobbágy ◽

H. Stroh ◽

R. Van Ammel ◽

...

Keyword(s):

Mass Spectrometry ◽

Alpha Particle ◽

Half Life ◽

Specific Activity ◽

Isotope Dilution Mass Spectrometry ◽

Standard Uncertainty ◽

Mass Content ◽

A Value ◽

Activity Measurements ◽

Relative Standard

AbstractThe half-life of 243Am has been measured by an absolute and a relative method, i.e. by determining the specific activity of 243Am and the specific activity ratio with 241Am. A mixed 241,243Am reference material was produced and certified for its americium mass content and its isotope amount ratios. The characterisation of the mass content of 243Am was established by isotope dilution mass spectrometry using an 241Am spike, produced from highly enriched 241Pu material. The isotope amount ratios n(241Am)/n(243Am) and n(242mAm)/n(243Am) were measured by thermal ionisation mass spectrometry. Activity measurements were performed by alpha-particle counting at a defined solid angle, as well as high-resolution alpha-particle spectrometry. From the 243Am/241Am activity and isotopic amount ratios, a value of 16.988 (24) was derived for the 243Am/241Am half-life ratio. Using a value of 432.6 (6) a for the 241Am half-life, the corresponding 243Am half-life value, 7349 (15) a, is in good agreement with the result obtained from the absolute method, 7342 (14) a. The mean value, 7345 (14) a, agrees well with data from literature and lowers the relative standard uncertainty to 0.2%.

Download Full-text

Dating of Polar Ice By 32Si

Journal of Glaciology ◽

10.1017/s0022143000031828 ◽

1973 ◽

Vol 12 (66) ◽

pp. 411-416 ◽

Cited By ~ 47

Author(s):

Henrik B. Clausen

Keyword(s):

Half Life ◽

Specific Activity ◽

Greenland Ice Sheet ◽

Cosmic Ray ◽

Polar Ice ◽

Poor Knowledge ◽

The Poor ◽

Glacier Ice ◽

Cosmic Ray Flux

32Si dating of glacier ice has hitherto been complicated by the poor knowledge of the half life. Furthermore, fall-out of bomb-produced 32Si impedes the determination of the specific activity of cosmic-ray produced 32Si in recent precipitation. Measurements on well-dated pre-bomb samples from the Greenland ice sheet establish a calibration for 32Si dating of up to 1 000 year old polar ice samples of the magnitude of 1 metric ton. If the technique is used on temperate glaciers, samples of pre-bomb deposits (or from after 1970) must be collected for comparison with samples of old ice, using an apparent half life of 295±25 years. Due to secular cosmic-ray flux variations, the true half life of 32Si is estimated at the slightly higher value of 330±40 years.

Download Full-text

First direct determination of the 93Mo half-life

Scientific Reports ◽

10.1038/s41598-021-99253-5 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

I. Kajan ◽

S. Heinitz ◽

K. Kossert ◽

P. Sprung ◽

R. Dressler ◽

...

Keyword(s):

Half Life ◽

Liquid Scintillation ◽

Specific Activity ◽

High Resolution Mass Spectrometry ◽

Direct Determination ◽

Chemical Separation ◽

Decontamination Factor ◽

Nuclear Facilities ◽

Analysis Techniques

AbstractThis work presents the first direct measurement of the 93Mo half-life. The measurement is a combination of high-resolution mass spectrometry for the determination of the 93Mo concentration and liquid scintillation counting for determining the specific activity. A 93Mo sample of high purity was obtained from proton irradiated niobium by chemical separation of molybdenum with a decontamination factor larger than 1.6 × 1014 with respect to Nb. The half-life of 93Mo was deduced to be 4839(63) years, which is more than 20% longer than the currently adopted value, whereas the relative uncertainty could be reduced by a factor of 15. The probability that the 93Mo decays to the metastable state 93mNb was determined to be 95.7(16)%. This value is a factor of 8 more precise than previous estimations. Due to the man-made production of 93Mo in nuclear facilities, the result leads to significantly increased precision for modelling the low-level nuclear waste composition. The presented work demonstrates the importance of chemical separations in combination with state-of-the-art analysis techniques, which are inevitable for precise and accurate determinations of nuclear decay data.

Download Full-text

A redetermination of the half-life of239Pu by specific activity measurements

Journal of Radioanalytical Chemistry ◽

10.1007/bf02518350 ◽

1981 ◽

Vol 64 (1-2) ◽

pp. 181-193 ◽

Cited By ~ 5

Author(s):

D. Brown ◽

K. M. Glover ◽

M. King ◽

G. Phillips ◽

F. J. G. Rogers ◽

...

Keyword(s):

Half Life ◽

Specific Activity ◽

Activity Measurements

Download Full-text

Determination of the levels of HPr and enzyme I of the phosphoenolpyruvate–sugar phosphotransferase system in Escherichia coli and Salmonella typhimurium

Canadian Journal of Biochemistry and Cell Biology ◽

10.1139/o83-005 ◽

1983 ◽

Vol 61 (1) ◽

pp. 29-37 ◽

Cited By ~ 21

Author(s):

Roshan L. Mattoo ◽

E. Bruce Waygood

Keyword(s):

Escherichia Coli ◽

Salmonella Typhimurium ◽

Specific Activity ◽

Phosphotransferase System ◽

E Coli ◽

Crude Extracts ◽

Activity Measurements ◽

A Cell ◽

Enzyme I

The levels of histidine-containing protein HPr and enzyme I of the phosphoenolpyruvate–sugar phosphotransferase system of Escherichia coli strains 1100, NC3, W3110, and P650 and Salmonella typhimurium strains SB3507 and LJ144 have been determined by quantitative sugar phosphorylation assay and immunochemically. The levels have been determined for cells grown on minimal salts with glucose, fructose, mannitol, glycerol, and lactate and on nutrient broth. All determinations indicate a two- to three-fold change in the levels of enzyme I and HPr between growth on hexoses, which gave the higher levels, and the other growth substrates. The highest levels were not always found in glucose-grown cells. Antibodies were produced in rabbits using purified proteins from E. coli P650. The activity measurements and immunochemically determined enzyme I protein gave specific activities in the crude extracts of E. coli strains which were similar to that of the pure enzyme. The wild-type S. typhimurium enzyme I in crude extracts did not have the same immunochemical reactivity, although there was a considerable cross-reaction and the specific activity appeared to be half that of pure enzyme I. The HPr from both E. coli and S. typhimurium behaved identically and, although the immunoprecipitation was weak, it did indicate that HPr assays may not be as reliable as the enzyme I assays. The relative amounts of enzyme I and HPr found indicate that there are between 10- and 20-fold more HPr molecules in a cell than enzyme I subunits which form active dimers.

Download Full-text