Abstract: A DNA sequencing process using specific stable isotopes associated with specific terminators for labels. The process includes a step of incorporating a stable isotope in at least one of the deoxynucleoside triphosphates and/or the dideoxynucleoside triphosphates such that a terminated strand has included within it or at the end a stable isotope such as an isotope of sulphur. Replicated strands are then separated by performing gel electrophoresis thereon. The location of the DNA strand with the stable isotope assigned to a terminator is analyzed preferably by resonance ionization spectroscopy. The stable isotopes can be chosen such that specific labels are assigned to at least one, and preferably to each base, in the dideoxynucleoside triphosphates. In the preferred embodiment, each of the bases (A, T, G and C) are associated with a specific stable isotopic label, and can be analyzed in a single track which enhances the accuracy of the sequencing process.

Abstract: A dosimeter which incorporates new methods for determining neutron dose. Less than one millirad of dose due to neutrons of all energies down to approximately 10.sup.3 eV can be measured, and the response can be adjusted by design of the dosimeter. The dosimeter utilizes the sputtering of material from a target due to the action of the neutrons and measuring of the amount of sputtered material to determine the dose. The sputtered material may be, for example, a noble gas or an inert solid. Various radiator materials can be included to interact with the neutrons so that the resulting charged particles control the sputtering process and hereby increase the sensitivity of the dosimeter. The target material can be, for example, noble-gas-impregnated polycrystalline or amorphous metals. The sputtered material is analyzed using resonance ionization spectroscopy, sputter-initiated resonance ionization spectroscopy or other methods to determine its quantity and hence the neutron dose.

Abstract: Apparatus and method are described for the quantitative analysis of a specific specie within a sample. The analysis has sufficient sensitivity for the detection of as little as one atom of the desired species. The method is accomplished by bombarding a sample with a highly focused charged particle beam; for example, a beam of positive argon ions having an energy from five to thirty kilovolts and a current of one milliampere or greater. This beam impinging upon the sample creates a cloud including secondary ions and neutral particles of the constituents of the sample. The cloud is irradiated with a laser beam having selected wavelengths therein for the unique ionization of the desired specie by means of resonance ionization spectroscopy (RIS). In most applications some energy and/or mass discrimination is required. The energy discrimination can be accomplished by passing the RIS ions through an energy filter, with the ions emanating therefrom having a narrow range of energy.

Abstract: Precise quantification of turbidity is obtainable through multiple determinations of the light attenuation coefficient of the particulate-bearing medium at a plurality of path lengths in the attenuating medium, and through multiple determinations of the scattering coefficient of the particulate-bearing medium at a selected angle of incidence and at a plurality of path lengths in the attenuating medium. In the preferred apparatus, these determinations employ a common light source and a common detector. In the present system, there are eliminated such adverse factors as light-source instability, detector instability, variations in particulate deposits on windows, and other problems, through the use of the ratio of the intensity measurements at different locations in the medium.