PHYSICS DIVISION PROGRESS REPORT FOR JULY 1, 1959 TO SEPTEMBER 30, 1959

Technical Report · Mon Oct 31 04:00:00 EST 1960

OSTI ID:4188213

Studies of gamma rays following capture of thermal neutrons in the elements from hydrogen to gallium, except oxygen and the noble gases, are reported. A few of the heavier elements such as lead and bismuth were also stadied. The neutron beam from the NRX reactor and associated equipment are used to implement the stadies. The angular correlation of two successive gamma rays is reported, and detailed studies of neutron capture in Nd/sup 143/ Gd/sup 155/, and W gave information on the nuclear level schemes with energies, spins, and parities. Measurement of the capture gamma ray from deuterium wae also made. Distortion of the nucleus beyond its elastic limit during fission is being studied. A study of the thermal neutron induced fission of U/sup 235/ revealed a hitherto unobserved fine structure in the prompt mass yield curve. This corresponds to one observed in the mass yield curves obtained by radiochemi-cal methods after neutrons are emitted from the fragments. The fine structure is intimately connected with the occurrence of closed tightly-bound shells (50 to 82 nucleons) in the structare of certain fragment nuclei. Energy changes and angular distribution of slow neutrons scattered by crystals were used in measurements of dispersion for the lattice vibrations of NaI at 110 deg K. These measumements were made for the three symmetric crystal directions. A model based on a simplified polarizable ion was also developed and is used to describe much of the experimental data. Similar measurements were made on lead at 110 deg K to its melting point. The results show the existence of nonnegligible forces between atoms out to fifth neighbors. A principle of magnetic focusing of charged particles is being studied by numerical methods. The C/sup 14/(p,n)N/sup 14/ and C/sup 14/(p, gamma )N/sup 15/ reactions show interference between two 1/2 + states in the compound nucleus N/sup 15/ at a proton energy of about 1.3 Mev. The interfering pair have different isotopic spin T. One level (T = 3/2) is believed to be the analogue of the ground state of C/sup 15/ and one (T = 1/2) has no analogue in C/sup 15/. This observed mixture can be accounted wholly as due to the coulomb perturbation which introduces an asymmetry in the otherwise charge-independent nuclear forces. Work continued on several projects aimed toward development of transistor units for reactor control. Two general purpose read-out systems, one using relays and the other transistors, were developed and applications are being studied. Develepment of printed circuit cards for fast- Blow coincidence experiments continued. Fast transistor amplifiers with band widths about 80 Mc/sec, and double delay-line amplifiers for use in the slow channels were tested. (For preceding period see PR-P-42.) (J.R.D.)

• Research Organization: Atomic Energy of Canada Ltd. Chalk River Project, Chalk River, Ont.
• NSA Number: NSA-14-008835
• OSTI ID: 4188213
• Report Number(s): PR-P-43; AECL-954
• Country of Publication: Canada
• Language: English

Related Subjects

AMPLIFIERS-- CIRCUITS-- COINCIDENCE METHODS-- CONTROL SYSTEMS-- ELECTRONIC EQUIPMENT-- ENERGY-- ENERGY LEVELS-- GADOLINIUM 155-- NEODYMIUM 143-- PARITY-- PLANNING-- REACTORS-- SPIN-- TRANSISTORS-- TUNGSTEN
ANGULAR DISTRIBUTION-- ATOMS-- CRYSTALS-- DISPERSIONS-- ENERGY-- INTERACTIONS-- IONS-- LATTICES-- LEAD-- LOW TEMPERATURE-- MEASURED VALUES-- MELTING POINTS-- NEODYMIUM 143-- POLARIZATION-- SCATTERING-- SODIUM IODIDES-- THERMAL NEUTRONS-- VIBRATIONS
ANGULAR DISTRIBUTION-- CAPTURE-- ENERGY-- ENERGY LEVELS-- GADOLINIUM 155-- GAMMA RADIATION-- MEASURED VALUES-- NEODYMIUM-- NEODYMIUM 143-- NEUTRONS-- PARITY-- SPIN-- TUNGSTEN
BISMUTH-- CAPTURE
PHYSICS