A number of pipetting aids are commercially available which obviate the necessity of filling pipets by oral suction. Most of the commercially available devices involve fitting the pipet into a soft tight fitting bushing and filling by means of either a piston or a rubber bulb. The pipet is then emptied by means of a valve control which permits, it is claimed, a dispensing accuracy of 0.1mL. It is at once apparent that the probable error (10% for a 1 mL. pipet) is considerably greater than is permissible for great precision. In practice these devices are found to be awkward and after a period of use tend to become even more so due to corrosion of the valve and aging of the rubber bushing and rubber bulbs.

The Chase two-dimensional analyzer is a 64 channel by 64 channel analyzer with a magnetic drum memory and a buffered storage system. The memory capacity is 2 counts per channel. The maximum storage rate is limited by the drum speed and is about 800 counts per second for a featureless spectrum.

The recently developed "n" on "p" type silicon solar cell has been evaluated for application as a high-level gamma radiation dose rate meter. The solar cell ionization current was found to be a linear function of dose rate in a range 10 2 to 10 7 rads per hour. A degradation rate of approximately one per cent per megarad was measured after stabilization with twenty megarads of cobalt-60 gamma radiation. The system has proven to be stable over long periods of time. Temperature dependence corrections have been found to be .0 per cent per degree centigrade between 0 and 60 degree centigrade.

A uniform intensity flat top spill-out cannot be obtained by manual control for two reasons: 1. The horizontal density of the internal beam of the Cosmotron is far from uniform. As a result, a manually controlled linear motion of the internal beam into a target will result in a non-uniform spill-out intensity. 2. Stability requirements of the Cosmotron magnet voltage are not easily met without feedback because of inherent component stability. The proposed servo system will sense the external beam intensity, and correct the magnet voltage to keep this intensity constant. This servo must operate through the transfer function of the main ignitron system and the flat top filter. Both of those transfer functions impose special problems.

The Brookhaven proton synchrotron (Cosmotron) is capable of accelerating protons to energies as high as 3.0 BeV. The biologic effects of particle bombardment at these energies have not been investigated but are of considerable radiobiologic interest. In addition, particle beams have long been discussed with regard to their potential usefulness in medical therapy, and actual clinical applications have been made, although at lower particle energies. Recent rapid advances in space technology have raised serious questions regarding the dosimetry of cosmic and solar radiations, the spectra of which contain energies in excess of those which have been investigated experimentally. For all of these reasons, we have recently begun a study of the effects of protons at 2.0-2.2 BeV, using the external beam of the Cosmotron.

Many workers have recently attempted to evaluate the P-wave strength function from a measurement of average capture cross sections or average total cross sections in the kiloelectron volt region. The primary interest of these measurements has been to determine the strength of the spin-orbit potential in the optical model. In view of the interest in determining the size of the spin-orbit coupling and in view of the considerable disagreement group has undertaken to measure the average total neutron cross sections from 10 to 100 keV in the region of the P-wave giant resonance. The following elements were studied: Nb, Mo, Rh, Ag, Cd, and In. The wok was carried out at the BNL-AECL fast chopper facility at Chalk River, using an 88-meter flight path and a nominal resolution of 15 nsec/meter.

The descriptive parameters of a waveguide with smooth or periodic structure are most easily measured in a waveguide section of suitable length which is transformed into a resonant cavity by placing short circuits at both ends. Measurements of dispersion diagram, phase velocity, group velocity, voltage attenuation coefficient, shunt impedance, field configuration, etc. all involve some form of perturbation technique. The introduction of a perturbing object in a resonant cavity changes the stored electric energy We and magnetic energy Wm by Δwe and ΔWm' resulting in a frequency shift Δf of the resonant frequency f, which is given by the perturbation formula of J. Muller.

We undertook the present diffraction study of the bifluoride ion in sodium acid fluoride and the present refinement of the earlier data on potassium acid fluoride with the hope of obtaining more accurate information not only on the position of the hydrogen atom, but also on the vibrations of the ion. We felt that it would be through the combination of information on the motions of the system from diffraction and spectroscopic studies that the question of the symmetry of the ion could be settled. In this paper we summarize briefly the results of our diffraction study and show that these data, in combination with the spectroscopic data, provide new, and we feel convincing, evidence that the F-H-F ion is linear and symmetric.

The Brookhaven Bubble Chamber Group is developing a Hough-Powell fast analysis system (HPD)1 for bubble chamber photographs. High precision measurements are made with a computer controlled flying spot digitizer. We are currently testing the track selection programs for the system. We have just completed a study of a method for automatic bubble density measurements.

The increasing complexity of the data of nuclear physics has led to widespread interest in the possibility of utilizing a digital computer for on-line data collection. Through the combined efforts of the Instrumentation Division and the Neutron Physics group at Brookhaven such a system has been placed into operation. Several features of this system are believed to be unique and of interest to research groups centered about a major facility like a reactor or an accelerator.

If one injects into an animal H3-thymidine, 50% of it is incorporated into deoxyribonucleic acid (DNA), within approximately 30 to 45 minutes, while the rest is catabolized. A storage of H3-thymidine for later incorporation into DNA does not occur, on the basis of available evidence. Once incorporated, the label remains bound to DNA until cell death and no unequivocal evidence has as yet been presented to indicate metabolic renewal or intracellular turnover of the DNA molecule. The loss of labeled DNA from the bone marrow is therefore directly influenced by the rate of proliferation of the various cell types with release of mature cells into the peripheral blood.

Investigations on the relative biological effectiveness (RBE) of densely ionizing radiations (with high LET, rate of linear energy transfer) are of importance in both fundamental and applied radiobiology. In the latter, they serve as a basis in setting permissible exposure levels for types of radiation about which little long range experience is available. Some of the best RBE studies have been done on chromosomal aberrations. The difficulty is determining RBE on the basis of chromosomal exchanges or 2-break aberrations is that the dose-response curves differ for radiations of different LET and dose rate. The dose-squared term tends to predominate with radiations of low LET (such as γ rays and most X rays) and high doses or dose rates; the linear term dominates with high LET tracks in general and at low doses or dose rates. The shape of the curves is thought to reflect the existence of two classes of mechanisms by which chromosome exchanges are produced; exchanges caused by the passage of a single ionizing particle account for the linear component of the dose-response curve, exchanges due to the interaction of effects of two independent ionizing particles are responsible for the dose-squared component. This model has been amply confirmed …

Early effects obtained with monoenergetic fast neutrons in mice have been described elsewhere. Emphasis in this report will be placed on the late effects of lens opacification (cataractogenesis), particularly during the period soon after irradiation with low or fractionated doses of neutrons at two energy levels, or X-rays. Considerations will also be given to the influence of age at time of irradiation upon the induction of lens opacities. Both studies are continuing, with periodic slit-lamp microscope examinations, but findings to date warrant this initial report at this conference.

In brief, these facilities consist of a 250 KvP X-ray generator; two areas of a research reactor, one a well thermalized unit of moderate capacity and a larger area with a mixed thermal and fast neutron distribution, all of which are used for brief, acute exposure. A 10 acre field, currently with almost 4000 curies of cobalt 60, serves to irradiate entire plants for either short or long periods of time. Recently, the flux density of the thermal column was increased by a factor of 5 over the original density. This was accomplished by lowering the thermal column 12 inches deeper into the reactor shield. Fast neutrons at this higher flux density are also available to the cooperator. An additional facility available to the program is the array of kilocurie gamma sources in the Nuclear Engineering Department of Brookhaven National Laboratory.

It has been previously reported that within twenty days following bombardment of mice 10 MeV protons (as well as with 20 MeV deuterons and 40 MeV alpha particles) that atypical epithelial hyperplasia developed without underlying recognizable vascular or collagen alterations as predisposing factors. The source of these monoenergetic accelerator-produced heavy ionizing particles was the 60-inch cyclotron of the Brookhaven National Laboratory. The technique employed utilized a variable-thickness filter in the beam in order to deliver multiple Bragg peaks in depth in the path of the charged particles in the tissue being irradiated. In this way a cylinder of skin was bombarded with essentially uniform ionization limited to a depth of 1-2 mm. In some instances the epidermal lesions resulting from an exposure of 2000 to 5000 rad resembled the type of lesion considered in the skin of man to be carcinoma in situ. The eventual fate of such lesions then constituted a question of importance in the possible relationship atypical hyperplasia in the pathogenesis of carcinoma in situ and of invasive carcinoma in skin. It is with this problem that the currently reported study is concerned.

It has been well established that even small doses of radiation will shorten life expectancy of animals, and that in general the causes of death are the same for the irradiated as for the normal animals. When x or γ rays are compared with neutrons in their ability to shorten the life span, some interesting differences appear. All available data from different laboratories on the shortening of the life span by x or γ on the one hand and neutrons on the other, have been compared. In spite of the obvious difficulties in comparing such data, if one expresses dose in terms of the LD 50/30 dose required for acute survival, one can pool the data from other laboratories and plot them on a single graph without excessive error. Results of such a compilation for single acute exposures are shown for x or γ rays in Figure 1 and for neutrons in Figure 2.

The radiolysis of several polyaromatic compounds which might be used as coolant material in a reactor was investigated using both gamma and reactor radiation. The compounds selected were naphthalene, anthracene, naphthacene, pyrene, phenanthrene, 1, 2 benzanthracene, chrysene, triphenylene, 9, 10 dihydrophenanthrene, phenazine, 7, 8, benzoquinoline and m-phenanthroline, in addition to the uncondensed ring compounds, biphenyl, ortho, meta and para terphenyl and bibenzyl. Gas yields, percentage decomposition, percentage "high boiler" and number average molecular weights were determined. A correlation was found between radiation stability and electron affinity and singlet triplet excitation energies. The most stable compounds were the condensed ring compounds, naphthalene, pyrene, chrysene, phenanthrene and triphenylene.

A pool of material in steady-state turnover is a collection of identical molecules from which deletions are made at a constant rate, along with simultaneous addition of new identical molecules at the same rate, the total pool size remaining unchanged. It is of interest to consider what may be expected in the way of such pools among the various chemical species which can be isolated from biological systems. It is clear what the model requires, i.e. any molecule belonging to the pool must have as much chance as any other pool molecule to make its exit. This situation is approximated by molecules in solution in a well mixed volume of fluid, hence the choice of the word "pool." The mixing brings pool molecules into proximity with the exit mechanism in a random way.

The proton beam in the Cosmotron is accelerated to an energy of 2.3 billion electron volts by a radio frequency voltage which is impressed across an insulated gap in the ferrite loaded accelerating cavity of the vacuum chamber. To maintain a constant orbit radius as the beam is accelerated, the frequency of the accelerating voltage must increase from the initial value of 370 kc/sec to 4200 kc/sec during the one second magnet pulse. Over the entire 11:1 frequency range, a minimum gap voltage of 2000 volts rms must be maintained. At every instant throughout the magnet pulse, the frequency of this voltage must be a predetermined function of the magnet field to a high degree of accuracy. Frequency errors greater than about .2 percent result in loss of beam due to excessive radius changes. Smaller errors than this however, can excite fatal phase oscillations in the beam if they occur rapidly. As little as .005 percent frequency modulation can result in total beam loss if it occurs at a rate of several kc/sec, where the beam is most sensitive to such disturbances.

The purpose of this new series of reports is to present in roughly finished form the results of the various start-up experiments on the BNL reactor as soon as the analysis of the experimental data is completed.

A series of measurements was performed to investigate the gamma ray spectra, in the region from about 100 kev to about 3 Mev, resulting from the capture of thermal neutrons in a number of elements. The purpose of the experiment was to supplement the high energy capture gamma ray data in order to remove some of the ambiguities from the proposed energy level schemes and to obtain information for the Shielding Group of Brookhaven National Laboratory on elements normally found in reactors.