New technique for measuring photonuclear cross sections and its applications to the CU-63(y,n)CU-62 and C-12(y,n)C-11 reactions

A new technique for the determination of photonuclear cross sections is described in detail. It was applied to the CU-63(y,n)CU-62 and C-12(y,n)C-11 reactions from thresholds up to 60 Mev. The results obtained are consistent and are in good agreement with results obtained by different methods (1,2)

Cloud chamber identification of photodeuterons from copper

Evidence has been reported (1,2) for the production of deuterons in the disintegration of copper and sulfur by bromsstrahlung before 24 Mev. energy. In the more direct of these investigations (1), the presence of a deuteron group was inferred on the basis of range and grain-density measurement in nuclear emulsions, and led to a ratio of photodeuterons to photoprotons cited as 0.31 for copper. Due to the bearing which such a large deuteron group must have on the theory of photonuclear processes, an independent investigation of the photodeuteron yield from copper was undertaken

Cloud chamber measurement of electron pairs for determination of synchrotron spectrum

The x-ray spectrum of the Iowa State College synchrotron operating at 65 Mev. has been measured. The method consisted of the observation, in a magnetic cloud chamber, of the momentum of each member of electron pairs produced in the air filling of the chamber. Using the theoretical values of cross section for pair production and the results of recent experiments, the energy spectrum of the x-ray quanta was computed. Due to the pronounced forward directional characteristic of electron pairs produced at extreme relativistic energies, discrimination of one energy region with respect to another was avoided and no solid angle corrections were necessary . The results are in agreement with the energy spectrum predicted by the Bethe-Heitler theory

STOCHASTICITY

Detailed examination of computed particle trajectories has revealed a complexity and disorder that is of increasing interest to accelerator specialists. To introduce this topic, the author would like you to consider for a moment the analysis of synchrotron oscillations for a particle in a coasting beam, regarded as a problem in one degree of freedom. A simple analysis replaces the electric field of the RF-v cavity system by a traveling wave, having the speed of a synchronous reference particle, and leads to a pair of differential equations of the form dy/dn = -K sin {pi}x, (1A) where y measures the fractional departure of energy from the reference value {pi}x measures the electrical phase angle at which the particle traverses the cavity, and K is proportional to the cavity voltage; and dx/dn = {lambda}{prime}y, (1b) in which {lambda}{prime} is proportional to the change of revolution period with respect to particle energy. It will be recognized that these equations can be derived from a Hamiltonian function H = (1/2){lambda}{prime}y{sup 2}-(K/{pi})cos {pi}x. (2) Because this Hamiltonian function does not contain the independent variable explicitly, it will constitute a constant of the motion and possible trajectories in the x,y phase space will be just the curves defined by H = Constant, namely the familiar simple curves in phase space that are characteristic of a physical (non-linear) pendulum

Radiations of certain synchrotron-induced radioactivities

This work has born out the usefulness of scintillation counter techniques in connection with radioactivities produced by synchrotron irradiation. The activity of the sources produced has been ample for obtaining good statistical accuracy in short counting periods

The Disintegration of Praseodymium 142

The radiations from Pr-142 have been examined with a thin lens spectrometer. One gamma-ray was found having an energy of 1.576 Mev. The beta-spectrum is complex, the two groups observed having maximum kinetic energies of 2.154 Mev and 0.636 Mev. It is suggested that the high energy beta-group gives a transition to the ground state of Nd-142 and that the gamma-ray follows the low energy beta-transition. The half-life was found to be 19.1 hr. The electron distribution produced by bremsstrahlung, due to the absorption of the beta-rays, was observed

ROTATION OF MERCURY: THEORETICAL ANALYSIS OF THE DYNAMICS OF A RIGID ELLIPSOIDAL PLANET

The second-order nonlinear differential equation for the rotation of Mercury is shown to imply locked-in motion when the period is within the range (2T/3) [1-{lambda} cos 2{pi}t/T {+-} 2/3 (21{lambda}e/2){sup 1/2}], where e is the eccentricity and T the period of Mercury's orbit, the time t is measured from perihelion, and {lambda} = (B-A)/C measures the planet's distortion. For values near 2T/3, the instantaneous period oscillates about 2T/3 with period (21{lambda}e/2){sup -1/2}T

Education and older adults at the University of the Third Age

This article reports a critical analysis of older adult education in Malta. In educational gerontology, a critical perspective demands the exposure of how relations of power and inequality, in their myriad forms, combinations, and complexities, are manifest in late-life learning initiatives. Fieldwork conducted at the University of the Third Age (UTA) in Malta uncovered the political nature of elder-learning, especially with respect to three intersecting lines of inequality - namely, positive aging, elitism, and gender. A cautionary note is, therefore, warranted at the dominant positive interpretations of UTAs since late-life learning, as any other education activity, is not politically neutral.peer-reviewe