Diffusion theory and transport theory approaches to the problem of a nuclear reactor with a transverse air gap are compared. It is suggested that the differences in results for thin gaps is due to the fact that diffusion theory does not adequately represent the flux distribution in the immediate vicinity of the gap. For mathematical conveniences previous treatments of the gap problem have made use of fictitious image piles which exaggerate the neutron losses. The extent of the error is estimated by direct neutron leakage calculations.

The absorption bands induced in α-Al2O3 by gamma and reactor irradiation have been studied. The slight coloration due to γ-rays saturates. Bands specific to reactor irradiation have been found and their growth studied.

In a manner somewhat analogue to that employed by R. Margulies in his memo (BNL Log No. C-2985) on fast source corrections in sigma piles, corrections to be applied to the data obtained on the laid-up graphite in the BNL reactor have been calculated. The correction was computed for a Ra-Be source using the data of Seren and using a standard graphite density for the BNL pile of 1.69. Values of the correction for different experimental sets of data were computed for each of three different diffusion lengths measured parallel to the channels. A correction for diffusion lengths perpendicular to the channels was also determined.

The following remarks are made on the applicability of the double dispersion approach to the Beth-Salpeter equation introduced previously. 1) Any invariant solution of the Bethe-Salpeter equation in ladder approximation satisfies the double dispersion representation when the total energy-momentum is space-lake. 2) There are some exceptional invariant solutions which are not given by the previous method in the equal-mass case, but the existence of such solutions is very unlikely in the unequal-mass case. 3) In the case of the general separated kernel the previous results give the correct solutions even if the kernel does not reproduce the double dispersion representation.

During the past year notable progress was made in several laboratories on design for linear accelerators in the energy range up to and above 1 Bev. Interest in linacs for this energy centers on two possible applications: first, as injectors for 300 to 1000 Bev synchrotrons, and second, as sources of intense meson beams. To review this progress, a conference jointly sponsored by the Brookhaven National Laboratory and Yale University was held at Brookhaven during the week of August 20, 1962.

This note describes some results of the study of single pion production in π⁻-p interactions at 4.65 Bev/c, using the BNL 20" Hydrogen Bubble Chamber. It is well known that the observability of some of the particle resonances (e.g. 33 Isobar and η) varies markedly with the energy of the incident particle. The ρ meson has been observed in π⁻-p interactions at 1.25 Bev/c and 1.9 Bev/c incident pion energies. Evidence will be shown that this resonance persists with the much higher incident pion energy used in the present experiment.

Using requirements of analyticity and the unitarity of the S-matrix we obtain the dependence of a transition amplitude on the invariant mass of two particles strongly coupled to other two particle channels. As an example, we consider the production of a Σπ state near the Y*₀ resonance assuming it is coupled to a KN state in an s 1/2 state.

In the memorandum entitled "Stored Energy in BNL Reactor Graphite", dated February 25, 1953, there is described an experiment conducted by Gurinsky's group to determine the energy per gram of irradiated graphite released in a 200°C anneal. Similar experiments were subsequently conducted by W. Kosiba, differing from the original in two particulars: a) Instead of two graphite samples, one normal, and one irradiated, Kosiba used only an irradiated sample which he heated first to release the stored energy, and then again after the energy was released. In this way, he obtained time against temperature curves for both normal and irradiated graphite from the same sample. (These curves are graphed for each run in Figs. 1 thru 5.) b) The vycor tubing used in the original experiment was not used by Kosiba. Five runs of this experiment were selected, Runs 4P, 13, 36, and 40 at furnace temperatures of 200°C, and Run 45 at a furnace temperature of 400°C.