Donald G. Ott

LIQUID SCINTILLATORS. III. THE QUENCHING OF LIQUID-SCINTILLATOR SOLUTIONS BY ORGANIC COMPOUNDS

Abstract A study has been made of the quenching characteristics of a large number of selected organic compounds in a few commonly encountered liquid scintillator solutions. From this it should be possible to anticipate the quenching difficulties associated with homogeneous liquid scintillation counting.

Substantial replacement of mammalian body carbon with carbon-13

Abstract Administration to weanling mice of a diet in which the digestible carbon fraction averaged 80 atom % carbon-13 led to an average tissue content of 60 atom % carbon-13 with little change in overall enrichment between 127 and 234 days of feeding. Urine and feces rapidly attained an isotopic steady state (in 7 days or less). The mice appeared to be in normal health throughout the experiment, and subsequently necropsy and microscopic examination of tissues revealed no abnormalities clearly attributable to the high isotopic enrichment.

Spectral Effects in the Comparison of Scintillators and Photomultipliers

Photomultiplier evaluation of scintillation performance is considered in the light of its marked dependence on spectral shape effects in the emission spectrum of the scintillator, in photon absorption of cell, reflector and photomultiplier window, and in the photoelectric conversion process. Relative pulse height data indicating gross differences in spectral sensitivity are presented for a group of 132 photomultipliers (types 6292 and 6342). A fluorescent converter for measuring the quantum output of liquid scintillators is described.Six scintillator solutions with fairly evenly spaced mean emission wavelengths from 3360 to 4660 A are evaluated for relative pulse height and relative photon output.Suggestions are presented for desirable methods for measuring the performance of scintillators.

Large-scale photosynthetic production of carbon-13 labeled sugars: The tobacco leaf system

Abstract A system is described for the production of carbon-13 uniformly labeled starch, glucose, fructose, and sucrose from kilogram quantities of tobacco leaves. Nearly 60% of the CO 2 administered (at 80 atom % carbon-13 or above) was found in these four compounds; the loss of enrichment between carbon-13 administered and isolated sugars was 3% or less. About 25 g 13 C-glucose can be produced in a 40-hr incubation from 1.2 kg of leaves. Label uniformity in the products was established by 13 C-nmr spectroscopy.

Heavy Methanes as Atmospheric Tracers

Methane-21 (13CD4) is potentially a useful nonradioactive tracer for testing atmospheric transport and diffusion models on a continental scale. In an experiment to demonstrate this long-range utility, the release of 84 grams of methane-21 was detected at distances of 1500 to about 2500 kilometers at concentrations of about 1 part in 2 x 1016 parts (by volume) in the air by a technique in which methane was separated and the methane-21 content was measured with a mass spectrometer.

Synthesis of 15N-labeled isomers of 5-Nitro-2,4-Dihydro-3H-1,2,4-Triazol-3-One (NTO)

Abstract The synthetic routes to 15N labeled 5-nitro-2,4-dihydro-3H-1,2,4-triazol-3-one (NTO) isomers are reported. Isomers labeled on N(6), N(4) and both N(1) and N(2) have been made. These compounds were identified by 1H, 13C, and 15N NMR and by mass spectral analysis. In many cases unequivocal NMR and mass spectral assignments were made.

Some history of liquid scintillator development at Los Alamos

The early developments in liquid scintillation counting made at Los Alamos Scientific Laboratory are reviewed. Most of the work was under the direction of F.N. Hayes and included counter development and applications as well as synthesis and chemistry of liquid scintillators.