Elementary Particles and Fields and String Theory Commons^™

Study Of Missing Mass Background In The Clas12 Detector, Jessie Hess, Gerard P. Gilfoyle, Lamya Baashen

Honors Theses

At Jefferson Lab we use the CLAS12 detector to measure the neutron magnetic form factor. An accurate measurement of the CLAS12 neutron detection efficiency (NDE) is required. We use the nuclear reaction ���� → ��′��+�� as a source of tagged neutrons and obtain the NDE from the ratio of expected neutrons to detected ones. We assume the final state consists of ��′��+�� only, use the ��′��+ information to predict the neutron's position(expected) and then search for that neutron(detected). We select neutrons with the missing mass (MM) technique. We use simulation to validate our methods. We simulated events with the Monte-Carlo …

Lifetime Measurement Of The Xi_C^+ Using Belle Ii Monte Carlo, Paul Gebeline

Honors Theses

This analysis uses simulated data from the Belle II experiment to measure the lifetime of the Xi_c^+ baryon. Three different decay modes are investigated to explore the feasibility and accuracy of such measurements at Belle II. The Xi_c^+ lifetime is measured using one of these modes after reducing backgrounds from sources other than the decay of interest. The final result is 464 +/- 15 fs, which is consistent with the expected result of 442 fs within uncertainty. This result shows that Belle II can make competitive measurements of particle properties and decays.

Aspects On The Quantum Dynamics Of A System Coupled To A Bosonic Environment, Qidong Xu

Dartmouth College Ph.D Dissertations

In this work we study various aspects of the quantum dynamics for a system coupled to a Bosonic environment, which is described by a collection of quantum harmonic oscillators or a quantum field. We first consider two quantum mechanical oscillator system-bath models obtained by dimensionally truncating linearized gravity coupled to a massive scalar field and scalar QED, and we show that they separately map onto the phase damped oscillator model and the oscillator system subject to two-photon damping. The phase damped oscillator model also corresponds to the optomechanical system with an acoustic field environment, and we study the acoustic environment …

Searching For Clean Observables In $B -> D* /Tau- \Bar{\Nu}_{\Tau}$ Decays, Michael D. Williams Jr.

Theses and Dissertations

In this thesis, the clean angular observables in the $\bar{B} \to D^{*+} \ell^- \bar{\nu}_{\ell}$ angular distribution is studied. Similar angular observables are widely studied in $B \to K^* \mu^+ \mu^-$ decays. We believed that these angular observables may have different sensitivities to different new physics structures.

Improvements For The T0c+ Geometry Of The Fast Interaction Trigger (Fit) Upgrade To Alice At The Cern Lhc, Noah Miller

Physics

The purpose of the ALICE experiment at CERN is to investigate the properties of the strongly interacting quark-gluon plasma formed in the high-energy collisions of lead nuclei in the CERN Large Hadron Collider. ALICE has been collecting data since 2009. The upcoming upgrade of the CERN LHC injectors during 2019-20 will boost the luminosity and the collision rate beyond the design parameters for several of the key ALICE detectors including the forward trigger detectors. The new Fast Interaction Trigger (FIT) will enable ALICE to discriminate beam-beam interactions with a 99% efficiency for the collisions generated by the LHC at a …

Observing Orbital Angular Momentum Transfer From Electron Vortex Beams To Matter, Hannah Devyldere

Senior Theses

It is possible to produce electron beams with non-zero orbital angular momentum. Such beams, known as electron vortex beams, are theoretically able to transfer their orbital angular momenta to matter, causing the matter to rotate. Nanoparticles in an aqueous solution were observed with an electron vortex beam to detect the transfer of orbital angular momentum in a low-friction environment. Observing the transfer of orbital angular momentum to particles in solution is difficult due to the necessity of imaging the particles through a liquid and the random movement of particles in the solution. Thus, orbital angular momentum transfer to matter could …

Cebaf Upgrade Bunch Length Measurements, Mahmoud Mohamad Ali Ahmad

Physics Theses & Dissertations

Many accelerators use short electron bunches and measuring the bunch length is important for efficient operations. CEBAF needs a suitable bunch length because bunches that are too long will result in beam interruption to the halls due to excessive energy spread and beam loss. In this work, bunch length is measured by invasive and non-invasive techniques at different beam energies. Two new measurement techniques have been commissioned; a harmonic cavity showed good results compared to expectations from simulation, and a real time interferometer is commissioned and first checkouts were performed. Three other techniques were used for measurements and comparison purposes …

Study Of The Structure Of 9C Via Single Neutron Transfer, Scott T. Marley

Dissertations

This thesis describes a study of the nucleus ⁹C, produced in the single-neutron transfer reaction d(¹⁰C, t) ⁹C using a radioactive ¹⁰C beam. The structure of the neutron-deficient nucleus ⁹C is poorly known. Only a few excited states have been observed and no information exists of their single-particle characteristics. The measured ground-state magnetic dipole moment of ⁹C is anomalously small and could imply large contributions from sd-shell orbitals in the ground-state wave function. The positions of the ⁹C excited states and their single-particle properties are vital to furthering the …

Electron Transmission Characteristics And The Production Of Narrow Beams Using Glass Optics, Buddhika Senarath Dassanayake

Dissertations

Transmission of electrons through an insulating single cylindrically-shaped glass capillary of microscopic dimension has been investigated. Samples made with Borosilicate glass (PYREX 7740) were subjected to bombardment of 300-1000 eV electrons. Transmitted electrons were analyzed using a parallel-plate spectrometer coupled to a channel electron multiplier.

The transmitted electron intensity was found to decrease with increasing sample tilt angle relative to the direction of the primary beam. Two regions of transmission were found: direct where there is no interaction of the beam with the inner capillary wall, and indirect where the beam does interact with the wall. The rate of transmission …

Positron Annihilation Ratio Spectroscopy (Psars) Applied To Positronium Formation Studies, Robert C. Slaughter

Theses and Dissertations

A Positron Annihilation of Radiation Spectrometer (PsARS) was developed and characterized. PsARS spectroscopy as well as digital Positron Annihilation Lifetime Spectroscopy (PALS) was applied to measure positronium formation on gold nanoparticles deposited through an evaporative method onto a thin capillary tube. This gold coated capillary tube was designed to be used for positronium lifetime studies in local electric field experiments. High local electric fields can polarize a positron-electron pair, which may result in an extended lifetime of the positron. These fields may be created through the interaction of an external electric field with silver nanoparticles deposited onto the surface of …

Excitation Of Hydrogen Atoms By Fast Protons, Edward Ellis Fitchard

Physics Theses & Dissertations

In this thesis a theoretical study is made of excitation of hydrogenic atom by charged particles such as protons or electrons. The approximation to the cross section for an inelastic scattering process is obtained under the following radically simplifying assumptions. The projectile is represented in its initial and final state by plane waves. All distortions are neglected whether they originate in an inelastic process or an elastic deflections of the charged particle by the nucleus. The perturbation of the atomic orbits between which the projectile induces transitions is neglected. Nonrelativistic hydrogenic wave functions are used for the electronic states. In …