Multiple cavity experiments to detect parity nonconservation in atomic hydrogen

We develop general guidelines and criteria for designing and evaluating beam experiments which use Ramsey's method of separated oscillating fields to detect PNC (parity nonconserving) effects in atomic hydrogen. We find that variation of the relative radio-frequency phases between different field configurations may offer distinct advantages in measuring and processing expected PNC data. We evaluate several specific experiments employing such multiple region designs.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/23951/1/0000198.pd

Memory Effects in Spontaneous Emission Processes

We consider a quantum-mechanical analysis of spontaneous emission in terms of an effective two-level system with a vacuum decay rate $\Gamma_0$ and transition angular frequency $\omega_A$. Our analysis is in principle exact, even though presented as a numerical solution of the time-evolution including memory effects. The results so obtained are confronted with previous discussions in the literature. In terms of the {\it dimensionless} lifetime $\tau = t\Gamma_0$ of spontaneous emission, we obtain deviations from exponential decay of the form ${\cal O} (1/\tau)$ for the decay amplitude as well as the previously obtained asymptotic behaviors of the form ${\cal O} (1/\tau^2)$ or ${\cal O} (1/\tau \ln^2\tau)$ for $\tau \gg 1$. The actual asymptotic behavior depends on the adopted regularization procedure as well as on the physical parameters at hand. We show that for any reasonable range of $\tau$ and for a sufficiently large value of the required angular frequency cut-off $\omega_c$ of the electro-magnetic fluctuations, i.e. $\omega_c \gg \omega_A$, one obtains either a ${\cal O} (1/\tau)$ or a ${\cal O} (1/\tau^2)$ dependence. In the presence of physical boundaries, which can change the decay rate with many orders of magnitude, the conclusions remains the same after a suitable rescaling of parameters.Comment: 13 pages, 5 figures and 46 reference

DISSOCIATIVE EXCITATION OF MOLECULAR HYDROGEN.

Author Institution: Department of Physics, The University of MichiganThe velocity spectrum of metastable H(2S) atoms produced by electron bombardment of $H_{2}$ has been measured by a time-of-flight technique. Two distinct groups of metastables have been detected. The slower atoms are interpreted as arising from transitions to attractive states just above the H(1S)+H(2S) dissociation limit. The absence of very slow atoms may indicate maxima in the relevant excited state potential curves at large internuclear separation. The faster atoms probably arise from transitions to doubly excited repulsive states, such as $(2s\sigma) (2p\sigma)^{1.3}\Sigma_{u} ^{+}$, The fast atom spectrum shows a strong dependence on observation angle