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.

In discussing this subject, data on radiation induced mammary gland neoplasia in the rat indicating that direct interaction between the radiation and target tissue is necessary for maximum neoplasia induction will be presented mainly. Other types of radiation induced neoplasia, in which little or no information on the mechanisms involved is available, will be discussed briefly. In particular, investigations on radiation induced mouse lymphoma will be reviewed, in which neoplasia appears to be an abscopal effect. Implications of these data will be discussed, particularly with regard to possible mechanisms involved, and extrapolation to man.

The generic term "chemonuclear" has been assigned to any chemical process system using nuclear energy as the prime energy source. The type of effect which induces the chemical change, or produces the chemical is of importance in classifying the type of chemonuclear process, or reactor involved. Four types of effects are identified for this classification. These are radiation, thermal, electrical, and photolytic effects. The radiation effects include the interaction with matter of high energy particles, or photons carrying energy in the range of a million electron volts (MEV) or higher, and causing primarily ionization effects. Thermal effects include transfer of thermal energy to matter and usually is directed towards producing a thermodynamic equilibrium in the system. Electrical effects are concerned with interaction with matter of particles carrying energy in the range of electron volts up to thousands of electron volts (EV to KEV). The photolytic effects utilize photon energy in the range of infrared through the visible to the ultraviolet radiation (IR, Visible, and UV). As is evident, this classification is somewhat arbitrary since it is primarily based on a division of the energy spectrum which is in reality continuous. It does, however, separate the more conventional methods of inducing …

The pioneer study by Benjamin and Sluka in 1908 on inhibition of antibody formation by X-rays revealed the importance of the temporal relationship between exposure to radiation and injection of antigen. X-radiation delivered three days before injection of beef serum inhibited precipitin formation in rabbits. A similar exposure to X-rays delivered three days after injection of the antigen failed to repress production of specific antibody. These observations were partially confirmed in 1915 when Hektoen reported inhibition of hemolysin production in the rat when X-radiation was delivered either before or after injection of sheep red cells. Although an absolute difference in radiosensitivity was not evident, the depressant effect of radiation on antibody production appeared to be less effective when radiation was given after injection of the antigen.

Iron containing approximately 0.01 wt. % carbon was quenched from 700°C and irradiated in the BNL reactor at 57°C for various lengths of time. The rate of decay of the Snoek internal friction peak was observed at 57°C after irradiation. After a 4-hour irradiation the rate of decay of the peak was one order of magnitude faster than the rate of decay in an unirradiated specimen. Longer irradiation times up to 48 hours caused no further acceleration of the decay rate. This observation implies that in the irradiated specimens there are ten times more precipitation nuclei than in the unirradiated specimens. This is confirmed by electron microscope studies which also show a factor of ten greater concentration of precipitate particles in specimens irradiated for 5 hours at 57°C as compared to an equivalent unirradiated specimen. Electron microscope studies also show that longer irradiation times do not increase further this number of precipitates. Although these experiments clearly demonstrate the enhancement of nucleation by neutron irradiation, it is not known why the incipient nuclei created by irradiation times of longer than 5 hours do not form observable precipitate particles.

Two methods for measuring target efficiencies are briefly discussed. The second method puts an upper bound on the efficiency and permits observation of instantaneous efficiency, thereby aiding location of losses. Measurements agree well with conventional radiochemical values.