FIRST EXPERIMENTAL RESULTS FROM DEGAS, THE QUANTUM LIMITED BRIGHTNESS ELECTRON SOURCE

The construction of DEGAS (DEGenerate Advanced Source), a proof of principle for a quantum limited brightness electron source, has been completed at the Lawrence Berkeley National Laboratory. The commissioning and the characterization of this source, designed to generate coherent single electron 'bunches' with brightness approaching the quantum limit at a repetition rate of few MHz, has been started. In this paper the first experimental results are described

Searching for physics beyond the Standard Model through the dipole interaction

The magnetic dipole interaction played a central role in the development of QED, and continued in that role for the Standard Model. The muon anomalous magnetic moment has served as a benchmark for models of new physics, and the present experimental value is larger than the standard-model value by more than three standard deviations. The electric dipole moment (EDM) violates parity ({$P$}) and time-reversal ({$T$}) symmetries, and in the context of the $CPT$ theorem, the combination of charge conjugation and parity ($CP$). Since a new source of {$CP$} violation outside of that observed in the $K$ and $B$ meson systems is needed to help explain the baryon asymmetry of the universe, searches for EDMs are being carried out worldwide on a number of systems. The standard-model value of the EDM is immeasurably small, so any evidence for an EDM would signify the observation of new physics. Unique opportunities exist for EDM searches using polarized proton, deuteron or muon beams in storage rings. This talk will provide an overview of the theory of dipole moments, and the relevant experiments. The connection to the transition dipole moment that could produce lepton flavor violating interactions such as $\mu^+ \rightarrow e^+ \gamma$ is also mentioned.Comment: Invited Plenary talk at the 19th International Spin Physics Symposium, Juelic

The neutron and its role in cosmology and particle physics

Experiments with cold and ultracold neutrons have reached a level of precision such that problems far beyond the scale of the present Standard Model of particle physics become accessible to experimental investigation. Due to the close links between particle physics and cosmology, these studies also permit a deep look into the very first instances of our universe. First addressed in this article, both in theory and experiment, is the problem of baryogenesis ... The question how baryogenesis could have happened is open to experimental tests, and it turns out that this problem can be curbed by the very stringent limits on an electric dipole moment of the neutron, a quantity that also has deep implications for particle physics. Then we discuss the recent spectacular observation of neutron quantization in the earth's gravitational field and of resonance transitions between such gravitational energy states. These measurements, together with new evaluations of neutron scattering data, set new constraints on deviations from Newton's gravitational law at the picometer scale. Such deviations are predicted in modern theories with extra-dimensions that propose unification of the Planck scale with the scale of the Standard Model ... Another main topic is the weak-interaction parameters in various fields of physics and astrophysics that must all be derived from measured neutron decay data. Up to now, about 10 different neutron decay observables have been measured, much more than needed in the electroweak Standard Model. This allows various precise tests for new physics beyond the Standard Model, competing with or surpassing similar tests at high-energy. The review ends with a discussion of neutron and nuclear data required in the synthesis of the elements during the "first three minutes" and later on in stellar nucleosynthesis.Comment: 91 pages, 30 figures, accepted by Reviews of Modern Physic

Quantum mechanics: an experimentalist's approach

Eugene D. Commins takes an experimentalist's approach to quantum mechanics, preferring to use concrete physical explanations over formal, abstract descriptions to address the needs and interests of a diverse group of students. Keeping physics at the foreground and explaining difficult concepts in straightforward language, Commins examines the many modern developments in quantum physics, including Bell's inequalities, locality, photon polarization correlations, the stability of matter, Casimir forces, geometric phases, Aharonov-Bohm and Aharonov-Casher effects, magnetic monopoles, neutrino oscillations, neutron interferometry, the Higgs mechanism, and the electroweak standard model. The text is self-contained, covering the necessary background on atomic and molecular structure in addition to the traditional topics. Developed from the author's well-regarded course notes for his popular first-year graduate course at UC Berkeley, instruction is supported by over 160 challenging problems to illustrate concepts and provide students with ample opportunity to test their knowledge and understanding

Weak interactions

In recent years, the study of weak interaction and its relationship with the other fundamnetal interactions of nature has progressed rapidly. Weak interactions of leptons and quarks provides an up-to-date account of this continuing research. The Introduction discusses early models and historical developments in the understanding of the weak force. The authors then give a clear presentation of the modern theoretical basis of weak interactions, going on to discuss recent advances in the field. These include development of the eletroweak gauge theory, and the discovery of neutral currents and of a host of new particles. There is also a chapter devoted entirely to neutrino astrophysics. Its straightforward style and its emphasis on experimental results will make this book an excellent source for students (problem sets are included at the end of each chapter) and experimentalists in the field. Physicists whose speciality lies outside the study of elementary particle physics will also find it useful

Quantum mechanics : an experimentalist's approach

xiii, 680 p.; 26 c

Theory and proposal for a quantum-degenerate electron source

We propose a pulsed electron source capable of a 6D brightness orders-of-magnitude greater than that of existing sources. It could deliver average current up to 0.5 pA and achieve an emittance approaching the quantum limit of one Compton wavelength in each spatial dimension. It could be employed to advantage in electron microscopy, inverse photo-emission, precision low-energy scattering experiments, and electron holography. This source could make possible pump-probe experiments with Angstrom spatial and sub-picosecond time resolution. Here we describe basic concepts of the source, including analysis of main issues that must be addressed for its successful construction and operation. We have begun an experiment to demonstrate its essential features