Bulletin of the American Physical Society
85th Annual Meeting of the APS Southeastern Section
Volume 63, Number 19
Thursday–Saturday, November 8–10, 2018; Holiday Inn at World’s Fair Park, Knoxville, Tennessee
Session C03: Instrumentation I |
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Chair: Kelly Chipps, Oak Ridge National Laboratory Room: Holiday Inn Knoxville Downtown Parlor |
Thursday, November 8, 2018 2:00PM - 2:12PM |
C03.00001: High Efficient Detection of Trace Actinides Elisa Romero-Romero, Alfredo Galindo-Uribarri, Yuan Liu, Daniel W. Stracener New methodologies for detecting trace amounts of actinide elements, such as U, Th and Pu, are being investigated for qualitative and quantitative analysis of unwanted impurities in the materials needed for ultra-low background experiments. An example is the next generation experiment LEGEND for searching neutrinoless double beta decay in 76Ge, which must have a half-life sensitivity higher than 1027 years. We have explored Accelerator Mass Spectrometry with negative ions produced with a Cs-sputtering source. However, the typical ionization efficiency for actinides ranges from 0.01% to 0.1%. We report on an alternative method based on laser resonance ionization with elemental selectivity to suppress the interfering and background ions. Efficient three-step ionization schemes for U, Th an Pu have been developed with a resonant ionization laser ion source. Overall ionization efficiencies of about 8% for U, 40% for Th and 51% for Pu have been obtained. We will describe how an analytical compact system using positive ions could be developed based on resonant laser selection for trace detection analysis. |
Thursday, November 8, 2018 2:12PM - 2:24PM |
C03.00002: Neutron Spin Echo Spectroscopy at the Spallation Neutron Source Piotr Adam Zolnierczuk, Laura Stingaciu, Michael Monkenbusch, Olaf Holderer, Stefano Pasini Neutron spin echo (NSE) spectroscopy is one of the most powerful techniques to study the dynamics of soft matter. The SNS-NSE instrument [1] at the ORNL Spallation Neutron Source is the first, and to date the only one, instrument for high resolution NSE spectroscopy installed at a pulsed neutron source. The main advantage of the pulsed source NSE is the ability to resolve the neutron wavelength and collect neutrons over a wider bandwidth. This allows us to determine S(Q,t) on a flexibly chosen quasi continuous (Q,t) grid that can be selected a posteriori, trading statistical error with grid resolution. We will present instrument capabilities of the SNS-NSE instrument and examples of soft matter experiments that have been performed using the SNS-NSE instrument. We will also show a new data reduction software called DrSPINE [2] that is capable to utilize all the information contained in a series of experiments consistently in one step and thus reduce the data from a pulsed-source SNS-NSE spectrometer as well as from a reactor-based J-NSE spectrometer [3]. References: [1] Ohl M. et al., Nucl. Inst. and Meth. A 696 (2012) 85-99 [2] P.A. Zolnierczuk et al. EPJ Web of Conferences, 83 (2015) 03020 [3] Holderer O. et al., Mess. Sci. Technol. 19 (2008) 034022
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Thursday, November 8, 2018 2:24PM - 2:36PM |
C03.00003: The next generation neutron detector for the study of exotic nuclei Joseph Heideman, David Perez-Loureiro, Robert K. Grzywacz, Mustafa M Rajabali, Lawrence Harvey Heilbronn, Jason Chan The development of radioactive ion beam facilities which can create very neutron rich nuclei necessitates detectors with improved neutron energy resolution and neutron selection. Exotic nuclei near the neutron drip line are far from beta decay stability and become more likely to undergo beta delayed neutron emission processes. The Neutron dEtector with Tracking (NEXT) will be a high resolution neutron detector designed as neutron-gamma discriminating-plastic scintillator coupled to silicon photomultipliers (SiPM's). The NEXT configuration will be based on ToF measurements with improved time resolution and interaction localization. Recent advancements in PSD plastic scintillators and SiPM's are the foundation of the compact design of the NEXT detector. Current development of the prototype includes optimizing SiPM timing capabilities and determining PSD characteristics of different plastic scintillators. Monte Carlo simulations have been developed to design a scintillator with optimal light collection and timing resolution. Results from ongoing project development will be presented in this contribution. |
Thursday, November 8, 2018 2:36PM - 2:48PM |
C03.00004: Developing all-in-one package SiPM package arrays for Nuclear Instrumentation Donnie T Hoskins The rapid development and decreasing prices of Silicon Photo Multipliers (SiPM) has made them a very attractive solution to read out scintillator materials. Moreover, SiPM are by nature very resistant to extreme environments at low temperature or high magnetic fields. Most commercial solutions simply integrate arrays of several small SiPM with common cathode and individual anodes readouts. These solutions have require external preamplifier solutions, with dedicated connections that will be prone to electronic pickup and noise. We have developed highly integrated SiPM packages including on-board preamplifiers for a variety of Nuclear Instrumentation. Here we will present the first results of the board performance using EJ-209 plastic scintillators and LaBr(Ce) Brilliance. |
Thursday, November 8, 2018 2:48PM - 3:00PM |
C03.00005: Beta-delayed neutron emission studies in 78Ni region with VANDLE at RIBF Ian C Cox, Robert K. Grzywacz, Rin Yokoyama, Thomas T King, Jeremy J Bundgaard, Aleksandra Fijalkowska, Shintaro Go, Andrew M Keeler, Miguel Madurga Flores, Shree Neupane, Shunji Nishimura, Maninder Singh, Krzysztof Piotr Rykaczewski An experiment using the VANDLE neutron time of flight detector setup, along with a LaBr3 HAGRiD and clover gamma ray arrays will measure the decay of the 78Ni and neighboring nuclei. This experiment will also include a newly developed YSO implant detector that will allow for a fast beta trigger used in the time of flight calculation. The neutron and gamma detectors allow for the complete measurements of both neutron bound and unbound states in 78Cu. With the decay strength distribution, one can calculate the lifetime for the neutron-rich nuclei in the region of the origin of the r-process. The proposed experiment at RIBF RIKEN is scheduled to occur late November of 2018, with the VANDLE setup, which is already completed and tested on site. |
Thursday, November 8, 2018 3:00PM - 3:12PM |
C03.00006: Designing Modular Multi-Wire Proportional Chambers for Cosmic Ray Muon Detection Michael Z Reynolds The Society of Physics Students (SPS) at Kennesaw State University is building a series of multi-wire proportional chambers as a tool to detect cosmic ray muons with the goal of doing muography on large structures. The chamber consists of two cathode plates that enclose an array of wires and is filled with an ionizing gas. To operate the chamber a voltage difference of approximately 2kV must be applied between the wires and the cathodes. High energy muons that pass through the chamber ionize the gas, and the resulting free electrons then avalanche towards the anode wires in a cascade of secondary ionization. This avalanche induces a current in the anode which we will detect with amplifier electronics. The chamber must be able to hold 2kV without any current leakage between the wires, which are spaced 3mm apart. This task is not trivial, as the electric field strength inside the chamber will exceed 4 million volts per centimeter near the anode wires. This region of high field strength is critical to avalanche formation and is based in the Paschen theory for breakdown voltages. After a redesign of the original chamber we were able to keep the anode wires at a stable high voltage, specifically by designing a custom circuit board using the CAD program Eagle. |
Thursday, November 8, 2018 3:12PM - 3:24PM |
C03.00007: Signal detection electronics for a Multi-Wire Proportional Chamber Jacob Barron The Society of Physics Students (SPS) at Kennesaw State University is building a series of Multi-Wire Proportional Chambers as a tool to detect cosmic ray muons with the goal of doing muon tomography on large structures. High-energy cosmic-ray muons passing through the chamber ionize the gas (in our case Argon/CO2 mix) and the resulting avalanche produces secondary ionization electrons which are deposited in the sense wires. The current pulse produced by this process is extremely small (on the order of nanoamperes) and also needs to pass through a row of capacitors which are used to isolate the high-voltage wires. this signal needs to be highly amplified in order to be detected. The op-amp chosen is the AD8099. This op-amp operates at high frequencies necessary to allow the cleanest possible signal for detection while giving high enough gain to send to a comparator for digital analysis. Once we have been able to separate the signal from the background electronic noise, we can fine tune the circuit by narrowing the bandwidth to the signal frequency. In addition to this the op-amp was simulated using LT Spice program to find the theoretical operational frequency. |
Thursday, November 8, 2018 3:24PM - 3:36PM |
C03.00008: Construction of a Multi-Wire Proportional Chamber for Muon Detection Emma I Pearson The Society of Physics Students (SPS) at Kennesaw State University is building a series of Multi-Wire Proportional Chambers as a tool to detect cosmic ray muons with the goal of doing muon tomography on large structures. Chamber construction is done using a 3-D printer. The chambers are required to be sealed and hold an ionizing gas, which in our case is an Argon/CO2 mix in an 80:20 ratio. The design of the prototype chamber was reworked such that the entire frame could be made in a single 3-D print operation, rather than as a series of printed pieces which needed to be sealed together. This modification allowed the chambers to hold the gas mixture properly without leaking. The geometry of the 3-D printing was done using SolidWorks, and the printing was done using a Makerbot Ultimaker 2 with PLA, a biodegradable, plant-based plastic. Once the frames were printed, both the sense wires and field-shaping wires needed to be attached and soldered under tension, with spacing between wires of 3 mm. Since the wires are extremely fine, (the sense wires are gold-plated tungsten with a diameter of 25 microns) the process of attaching them is not trivial, so grooves were added to the printed frame design to aid in the alignment of the wires. |
Thursday, November 8, 2018 3:36PM - 3:48PM |
C03.00009: Multi-Wire Proportional Chamber David N Joffe, Shu Cui The Society of Physics Students (SPS) at Kennesaw State University is building a series of Multi-Wire Proportional Chambers as a tool to detect cosmic ray muons with the goal of doing muon tomography on large structures.
To operate the chamber it is placed under high-voltage (approximately 2000V) and filled with an ionizing gas. High energy muons ionize the gas and the resulting electrons then avalanche towards the anode in a cascade of secondary ionization. This avalanche induces a current in the anode which we will detect with amplifier electronics, which will be described in detail in another talk.
As the electric field is not constant in the space between the wires, a 3-D computer simulation of the chamber under high voltage was done using COMSOL Multiphysics. The geometry of the chamber, sense wires and field shaping wires were modeled in COMSOL in order to produce both 2-D and 3-D plots showing both electric field strength and potential.
Information in the simulations is used to determine the optimal wire spacing and operational voltage of the chambers. It also allows for an understanding of the volume of gas in which the field is strong enough to produce an avalanche, and thus allows us to estimate the effective detection area. |
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