Bulletin of the American Physical Society
Fall 2009 Meeting of the Four Corners Section of the APS
Volume 54, Number 14
Friday–Saturday, October 23–24, 2009; Golden, Colorado
Session H3: Optical Techniques in Neutrino Physics |
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Chair: Christopher Sorenson, Kansas State University Room: Green Center 249 |
Saturday, October 24, 2009 11:20AM - 11:32AM |
H3.00001: Light Injection tests in P0D neutrino detector Timothy Walton The T2K experiment will measure neutrino mixing by sending a neutrino beam, created at the Japan Proton Accelerator Research Center (JPARC) in Tokai, Japan, over 290 km underground to the Super-Kamiokande detector. The neutrino beam at JPARC will be monitored by ND280 experiment which contains the Pizero Detector (P0D). The P0D contains around 11,000 scintillator bars, each with a wavelength shifting fiber connected to an avalanche photo diode sensor. These sensors, called MPPCs, are monitored by an LED light injection system developed at Colorado State University. We show the initial results of a study of the response of the MPPC sensors to the LED light pulses. We find unexpectedly large signal variation in some groups of MPPCs, and we determine the cause to be slight random height variations in the fibers themselves. [Preview Abstract] |
Saturday, October 24, 2009 11:32AM - 11:44AM |
H3.00002: Study of Charge Integration Electronics in Pi-Zero Detector of a Long-Baseline Neutrino Oscillation Experiment Rajarshi Das The Pi-Zero Detector (P0D), a part of Long Baseline Neutrino Oscillation experiment, uses a beam produced and characterized in Tokai, Japan and measured 295 km away in Kamioka. The P0D consists of around 10,000 scintillator bars with wavelength-shifting fibers attached to a Multi-Pixel Photon Counter that measures the energy deposited by neutrino interactions in the bar. The charge output from each photon counter is integrated during a few hundred nanoseconds windows, stamped with hit time, and then read out into a data acquisition system. We also use a Light Injection system to introduce a controlled amount of light into the fibers by pulsing a set of LEDs. Here we present a study of the signals measured in a sequence of integration windows from individual photon counters as well as distributions of hit times. Our results indicate a substantial effect for integration windows following a large signal and demonstrate the need to have further studies of integration electronics so we can eliminate possible effects of background to the interaction signals. [Preview Abstract] |
Saturday, October 24, 2009 11:44AM - 11:56AM |
H3.00003: Searching for the Mass of the Neutrino (Spectroscopy of Ba+ ions in Liquid $^{136}$Xe) Kendy Hall, Cesar Benitez, Bill Fairbank The goal of the Enriched Xenon Observatory (EXO) collaboration is to detect neutrino-less double beta decay using a ton size liquid $^{136}$Xenon detector with zero background. Such detection can only be achieved if the daughter $^{136}$Ba$^{+}$ ion that is present at decay site is tagged. The EXO collaboration is working towards several techniques to tag the Ba$^{+}$ ion. In-situ laser tagging of Ba$^{+}$ ions in a liquid xenon test apparatus is being developed at Colorado State University (CSU). Ba$^{+}$ ions are implanted in the liquid xenon by ablating a barium sample with a 1064nm Nd-YAG pulsed laser. In-situ laser tagging can only be accomplished if the spectroscopy of Ba$^{+}$ ions in liquid xenon is understood. This work's goal is to confirm the spectra of Ba+ ions in liquid xenon. The most recent results of the experiments at CSU will be presented. [Preview Abstract] |
Saturday, October 24, 2009 11:56AM - 12:08PM |
H3.00004: Double beta decay daughter ion detection in a solid xenon matrix for EXO Brian Mong, Shon Cook, William Fairbank $0 \nu \beta \beta$ experiments are the possibly the most sensitive means available to measure the absolute mass of the neutrino as long as backgrounds can be sufficiently suppressed. The Enriched Xenon Observatory (EXO) experiment may be able to eliminate all backgrounds by detecting the daughter of the $ 0 \nu \beta \beta$ $( ^{136}Xe \rightarrow ^{136}Ba +2e^{-} ) $ through optical fluorescence. We propose to grab the ion in the detector by freezing it in xenon ice on a cold probe, possibly an optical fiber, and then detecting it in the ice. We present progress in the detection of barium ions generated by an ion beam, and detected in a solid xenon matrix using CW laser excitation and efficient fluorescence detection. [Preview Abstract] |
Saturday, October 24, 2009 12:08PM - 12:20PM |
H3.00005: Application of Multiphoton Ionization of Liquid Xenon for Purity Measurements Julio Cesar Benitez Medina, Kendy Hall, William Fairbank Detection of fluorescence from single Ba$^{+}$ daughter ions in liquid xenon is a potential key method of background discrimination in the Enriched Xenon Observatory (EXO) double beta decay experiment. An important requirement is to have ultrapure liquid in order to ensure Ba$^{+}$ ion survival for many seconds. To measure the purity of liquid Xenon we produce electrons using a 355 nm and 266nm Nd-YAG pulsed laser. By varying the laser energy, we have demonstrated that these are two- and three-photon ionization processes, respectively. As the electrons travel in the liquid some may be lost by attachment to impurities. By measuring the fraction of electrons that survive, we can determine the purity of the liquid. Having a focused beam allows us to select where the electrons are created. [Preview Abstract] |
Saturday, October 24, 2009 12:20PM - 12:32PM |
H3.00006: Two-Dimensional Angular Scattering Instrument for Aerosol Characterization Matthew Berg, Steven Hill, Gorden Videen We describe the development of a novel light scattering apparatus to study single aerosol particles. The apparatus collects a particle's scattered light over two angular dimensions in the near-forward direction. Single particles are trapped in an electrodynamic levitator or dispersed in an aerosol flow and illuminated one-by-one by a 30ns pulsed 532 nm Nd:YAG laser. The optical arrangement uses a simple spatial filter to remove unscattered light from the near-forward direction, allowing collection of the scattered light within a two-dimensional angular range from 0.1$\sim $15 degrees centered on the forward direction. This angular range enables a simple power-law analysis of the scattered intensity, which can be used to obtain estimates of the particle size without recourse to complicated data analysis. [Preview Abstract] |
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