Development of Component Applications for the DESI Online System

The focus of this thesis project is on the development of applications for use in the DESI Online System, or DOS. DOS is the online system used for the control and management of the Dark Energy Spectroscopic Instrument (DESI). The DESI project will make measurements of the spectra of galaxies and quasars in order to provide data illuminating the nature of dark energy. The control system for this instrument is still in the development stage and must be finished in time for the start of the survey in 2018. As such, this project concerns the creation of the software applications needed to control the individual components of DESI, testing these applications through the use of simulators both provided by the component teams and developed alongside the applications, and finally integrating the applications into the full system. The three primary applications whose development is presented in this thesis are the Telescope Control System Interface, the Spectrograph Control application, and the Cryostat Reader application. These applications, which have been developed primarily in the Python language, will be vital to the operation of the DESI survey.  OSU College of EngineeringNo embargoAcademic Major: Engineering Physic

Scientific Verification Study of the Dark Energy Camera

Mathematical and Physical Sciences: 1st Place (The Ohio State University Denman Undergraduate Research Forum)In the past two decades, it has been found that our universe is expanding at an accelerating rate. The cause of this expansion is still unclear. One possible explanation is the existence of a new energy component with negative pressure, called “dark energy”, that is driving the expansion. The other explanation is that general relativity breaks down on cosmological scales. One way to investigate this phenomenon is by measuring the expansion history and growth of large scale structure in the universe. This can be done through the use of dedicated surveys which measure millions of astronomical objects. In order to study dark energy, the Dark Energy Survey (DES) collaboration has constructed the Dark Energy Camera (DECam), a specialized camera sensitive to light in the visible and infrared spectrum. The DECam has finished its testing period for the systems which compose the telescope and camera, and is approaching the completion of its first season of the survey. The goal of this project is to identify issues with the exposures taken by the DECam. First, catalogs of telescope, hexapod, and exposure data were made using Python scrips. This data was then analyzed, investigating relations between a number of factors such as telescope orientation and configuration, environmental conditions, and image quality. Various correlations were found or verified as a result of this analysis. These included, but were not limited to, correlations of the image offsets against the hexapod and telescope positions. Other correlations were found not to exist, such as a correlation between telescope position and shutter errors. These results reveal possible issues that, if corrected, may increase the quality of exposures taken by the DECam and prevent delays in its operation. Understanding this complex instrument and improving the quality of delivered images is an ongoing effort. The DECam began its survey in September in 2013 and will continue for 5 years.DOENSFSTFC (UK)Ministry of Education and Science (Spain)FINEP (Brazil)Collaborating Institutions: http://www.darkenergysurvey.org/collaboration/Academic Major: Engineering Physic

Construction and Impact of the High Energy Light Isotope Experiment's Ring Imaging Cherenkov Detector

Understanding the propagation processes of cosmic rays is critical to interpreting features in the cosmic-ray spectrum. HELIX (High Energy Light Isotope eXperiment) seeks to improve this understanding by measuring the chemical and isotopic abundances of light cosmic ray nuclei. HELIX is optimized to measure the abundances of the propagation clock isotope Be-10 and stable isotope Be-9 at energies between 0.2 and 3 GeV/n, an essential dataset for understanding the propagation history of cosmic rays. In addition, HELIX will measure the fluxes of all the light isotopes between protons (Z=1) and neon (Z=10). The HELIX instrument is a magnet spectrometer, designed to fly on a long duration balloon, and consists of a 1 Tesla superconducting magnet with a high-resolution drift-chamber tracker for measuring the particle rigidity, a time of flight detector for measuring charge and velocities at lower energies, and a ring-imaging Cherenkov detector (RICH) for measuring particle velocities at higher energies. Although containing contributions to many elements of HELIX's payload, the majority of this thesis project concerns the design, construction, and calibration of HELIX's RICH detector. This thesis will first give a scientific background on the basics of cosmic ray physics. It will then present an analysis demonstrating how HELIX's scientific goals motivate the development of the RICH detector and how its proper design and calibration affect the final results. Next, this thesis will discuss the properties of silicon photomultipliers (SiPMs), which are used to create the RICH detector's focal plane, as well as the work done to characterize and calibrate those selected for use in HELIX. This thesis will also discuss the development, debugging, and integration of the front end electronics used in the RICH's focal plane. Finally, it will outline the construction, installation into the payload, and in-place calibration of the full RICH detector

The DESI Experiment Part II: Instrument Design

DESI (Dark Energy Spectropic Instrument) is a Stage IV ground-based dark energy experiment that will study baryon acoustic oscillations and the growth of structure through redshift-space distortions with a wide-area galaxy and quasar redshift survey. The DESI instrument is a robotically-actuated, fiber-fed spectrograph capable of taking up to 5,000 simultaneous spectra over a wavelength range from 360 nm to 980 nm. The fibers feed ten three-arm spectrographs with resolution $R= \lambda/\Delta\lambda$ between 2000 and 5500, depending on wavelength. The DESI instrument will be used to conduct a five-year survey designed to cover 14,000 deg$^2$. This powerful instrument will be installed at prime focus on the 4-m Mayall telescope in Kitt Peak, Arizona, along with a new optical corrector, which will provide a three-degree diameter field of view. The DESI collaboration will also deliver a spectroscopic pipeline and data management system to reduce and archive all data for eventual public use

The DESI Experiment Part II: Instrument Design

DESI (Dark Energy Spectropic Instrument) is a Stage IV ground-based dark energy experiment that will study baryon acoustic oscillations and the growth of structure through redshift-space distortions with a wide-area galaxy and quasar redshift survey. The DESI instrument is a robotically-actuated, fiber-fed spectrograph capable of taking up to 5,000 simultaneous spectra over a wavelength range from 360 nm to 980 nm. The fibers feed ten three-arm spectrographs with resolution $R= \lambda/\Delta\lambda$ between 2000 and 5500, depending on wavelength. The DESI instrument will be used to conduct a five-year survey designed to cover 14,000 deg$^2$. This powerful instrument will be installed at prime focus on the 4-m Mayall telescope in Kitt Peak, Arizona, along with a new optical corrector, which will provide a three-degree diameter field of view. The DESI collaboration will also deliver a spectroscopic pipeline and data management system to reduce and archive all data for eventual public use

The DESI Experiment Part I: Science,Targeting, and Survey Design

DESI (Dark Energy Spectroscopic Instrument) is a Stage IV ground-based dark energy experiment that will study baryon acoustic oscillations (BAO) and the growth of structure through redshift-space distortions with a wide-area galaxy and quasar redshift survey. To trace the underlying dark matter distribution, spectroscopic targets will be selected in four classes from imaging data. We will measure luminous red galaxies up to $z=1.0$. To probe the Universe out to even higher redshift, DESI will target bright [O II] emission line galaxies up to $z=1.7$. Quasars will be targeted both as direct tracers of the underlying dark matter distribution and, at higher redshifts ( 2.1 < z < 3.5), for the Ly-$\alpha$ forest absorption features in their spectra, which will be used to trace the distribution of neutral hydrogen. When moonlight prevents efficient observations of the faint targets of the baseline survey, DESI will conduct a magnitude-limited Bright Galaxy Survey comprising approximately 10 million galaxies with a median $z\approx 0.2$. In total, more than 30 million galaxy and quasar redshifts will be obtained to measure the BAO feature and determine the matter power spectrum, including redshift space distortions

The DESI experiment part I: science, targeting, and survey design

DESI (Dark Energy Spectroscopic Instrument) is a Stage IV ground-based dark energy experiment that will study baryon acoustic oscillations (BAO) and the growth of structure through redshift-space distortions with a wide-area galaxy and quasar redshift survey. To trace the underlying dark matter distribution, spectroscopic targets will be selected in four classes from imaging data. We will measure luminous red galaxies up to $z=1.0$. To probe the Universe out to even higher redshift, DESI will target bright [O II] emission line galaxies up to $z=1.7$. Quasars will be targeted both as direct tracers of the underlying dark matter distribution and, at higher redshifts ($2.1 < z < 3.5$), for the Ly-$\alpha$ forest absorption features in their spectra, which will be used to trace the distribution of neutral hydrogen. When moonlight prevents efficient observations of the faint targets of the baseline survey, DESI will conduct a magnitude-limited Bright Galaxy Survey comprising approximately 10 million galaxies with a median $z\approx 0.2$. In total, more than 30 million galaxy and quasar redshifts will be obtained to measure the BAO feature and determine the matter power spectrum, including redshift space distortions

The DESI Experiment Part II: Instrument Design

DESI (Dark Energy Spectropic Instrument) is a Stage IV ground-based dark energy experiment that will study baryon acoustic oscillations and the growth of structure through redshift-space distortions with a wide-area galaxy and quasar redshift survey. The DESI instrument is a robotically-actuated, fiber-fed spectrograph capable of taking up to 5,000 simultaneous spectra over a wavelength range from 360 nm to 980 nm. The fibers feed ten three-arm spectrographs with resolution $R= \lambda/\Delta\lambda$ between 2000 and 5500, depending on wavelength. The DESI instrument will be used to conduct a five-year survey designed to cover 14,000 deg$^2$. This powerful instrument will be installed at prime focus on the 4-m Mayall telescope in Kitt Peak, Arizona, along with a new optical corrector, which will provide a three-degree diameter field of view. The DESI collaboration will also deliver a spectroscopic pipeline and data management system to reduce and archive all data for eventual public use