A shallow underground laboratory for low-background radiation measurements and materials development.

Pacific Northwest National Laboratory recently commissioned a new shallow underground laboratory, located at a depth of approximately 30 meters-water-equivalent. This new addition to the small class of radiation measurement laboratories located at modest underground depths houses the latest generation of custom-made, high-efficiency, low-background gamma-ray spectrometers and gas proportional counters. This paper describes the unique capabilities present in the shallow underground laboratory; these include large-scale ultra-pure materials production and a suite of radiation detection systems. Reported data characterize the degree of background reduction achieved through a combination of underground location, graded shielding, and rejection of cosmic-ray events. We conclude by presenting measurement targets and future opportunities.

Direct measurement of the 14N(p,gamma)15O S factor.

The 14N(p,gamma)15O reaction regulates the rate of energy generation in the stellar CN cycle. Because discrepancies have been found in the analysis and interpretation of previous capture data, we have measured the 14N(p,gamma)15O excitation function for energies in the range E(lab)(p)=155-524 keV. Fits of these data using R-matrix theory yield a value for the S factor at zero energy of 1.68+/-0.09(stat)+/-0.16(syst) keV b, which is significantly smaller than the previous result. The corresponding reduction in the stellar reaction rate for 14N(p,gamma)15O has a number of interesting consequences, including an impact on estimates for the age of the Galaxy derived from globular clusters.

Explosive hydrogen burning of 17O in classical novae.

We report on the observation of a new resonance at E(lab)(R)=190 keV in the 17O(p,gamma)18F reaction. The measured resonance strength amounts to omegagamma(pgamma)=(1.2+/-0.2)x10(-6) eV. With this new value, the uncertainties in the 17O(p,gamma)18F and 17O(p,alpha)14N thermonuclear reaction rates are reduced by orders of magnitude at nova temperatures. Our significantly improved reaction rates have major implications for the galactic synthesis of 17O, the stellar production of the radioisotope 18F, and the predicted oxygen isotopic ratios in nova ejecta.

A quantitative in vivo mouse model used to assay inhibitors of tumor-induced angiogenesis.

An in vivo model of tumor-induced angiogenesis was used to monitor two known inhibitors of angiogenesis, protamine sulfate and the steroid tetrahydro S. Tumor cells entrapped in alginate beads were injected s.c. into mice. Blood vessel induction was measured by two quantitative methods: measurement of hemoglobin at the alginate pellet site, and pooling of radiolabeled RBC to the alginate pellet site. The two methods gave parallel results. Tetrahydro S with or without heparin inhibited blood vessel growth by 50%, and protamine sulfate inhibited blood vessel growth by 85%. These results were supported by gross morphology and histological analysis of the alginate pellet site.

Biohazards symbol: development of a biological hazards warning signal.

The need for a symbol to warn of potential infection hazards became apparent during Public Health Service contract work on the development of containment facilities for virus-leukemia research. A program of direct inquiry and a search of the literature revealed that there was no universally used signal and that scientific and safety organizations concurred in the need for one. Criteria for symbol design were established, and final selection was based on "uniqueness" and "memorability." The National Institutes of Health is recommending use of the symbol as a warning of biological hazard.

Laboratory design for microbiological safety.

Of the large amount of funds spent each year in this country on construction and remodeling of biomedical research facilities, a significant portion is directed to laboratories handling infectious microorganisms. This paper is intended for the scientific administrators, architects, and engineers concerned with the design of new microbiological facilities. It develops and explains the concept of primary and secondary barriers for the containment of microorganisms. The basic objectives of a microbiological research laboratory, (i) protection of the experimenter and staff, (ii) protection of the surrounding community, and (iii) maintenance of experimental validity, are defined. In the design of a new infectious-disease research laboratory, early identification should be made of the five functional zones of the facility and their relation to each other. The following five zones and design criteria applicable to each are discussed: clean and transition, research area, animal holding and research area, laboratory support, engineering support. The magnitude of equipment and design criteria which are necessary to integrate these five zones into an efficient and safe facility are delineated.