The theory, design, and construction of a magnetically shielded solenoid are described. Three correction coils are employed in addition to the main solenoid winding. The solenoid is enclosed in three concentric magnetic shields which serve to screen the inner region of the solenoid from external magnetic fields. First the theory and design of a solenoid with correction coils and no magnetic shielding are discussed. Then calculations of the magnetic field due to a solenoid inside a closed cylinder of infinite permeability are summarized. These calculations show that a properly constructed shield can improve the homogeneity of the field due to a single solenoid by an order of magnitude. Optical pumping measurements of the field homogeneity in the central region and of the field distribution along the axis of the solenoid are reported. The measurements of the field distribution agree with the calculations to within a few hundredths of a percent. The shields reduce the disturbance due to changing external fields by a factor of 100. The main solenoid is 91.44-cm long and has an inner diameter of 32.41 cm. The solenoid field is 18.6 G/ A and the solenoid dissipates approximately 320 W when producing a field of 60 G. The solenoid-shield system has at 60 G a homogeneity of 1 part in 10 5 over an 8-cm-diam sphere at the center of the solenoid. Construction details of the shields and coils are given and the solenoid power supply is described.Garrett, J.
Experimental measurements have been made of the motion of a red brass harpsichord wire driven electromagnetically in a fixed direction perpendicular to the equilibrium position of the wire. The motion is complex compared to that predicted by simple linear theory because of effects due to tensional changes and longitudinal motions. Optoelectronic detectors are used to measure amplitude and phase of the transverse motions as functions of the driving frequency, both in the driving direction y and the direction z perpendicular to y. Near the free-vibration fundamental frequency f0 the z and y amplitudes are comparable even for a very low driving force and amplitude. Amplitude jumps and hysteresis effects are observed for large amplitudes. The z–y phase difference is measured as 0°, 90°, and 180° in different frequency regions, yielding both planar and whirling or tubular motion. As the driving frequency increases, the phase difference between the driving force and the y motion varies steadily from 0° to 90° before jumping to 180°. There is no evidence of a critical frequency of onset of the z motion as is predicted in some theoretical treatments. Similar effects are observed near 3f0, for which amplitude measurements have been made down to 0.01 μm for a 0.71-m-long wire.
The ground-state P branchings for several mass-separated Kr fission products and their daughters have been measured at the TRISTAN on-line separator facility at the Ames Laboratory Research Reactor. Absolute P counting was done with a 4~-geometry plastic scintillation detector and y spectra were taken simultaneously with a Ge(Li) detector. The deduced values of the ground-state P branching P~, expressed as a percentage of decays, are: ' Kr, 14+4 'Rb, 78.0~1.2 "Kr, 23~4 ' Rb, 25+5 Kr, 29+4~R bg 37+5; 'Kr, 10+4 'Rb, 5~5.RADIOACTIVITY ss, sa, ao. ai Kr ss. sa .ao. aiRb f+on 2ssU (+ f) j, Ge(Li) and 4~plastic scintillation detectors; deduced P, ; mass-separated parent Kr activities.
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