Bulletin of the American Physical Society
APS April Meeting 2017
Volume 62, Number 1
Saturday–Tuesday, January 28–31, 2017; Washington, DC
Session B9: Dark Matter: DarkLight, Sequest, Other Ongoing Efforts |
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Sponsoring Units: DPF Chair: Mike Tuts, Columbia University Room: Roosevelt 1 |
Saturday, January 28, 2017 10:45AM - 10:57AM |
B9.00001: Progress toward a Dark Photon Search with DarkLight Ross Corliss Despite compelling astrophysical evidence for the existence of dark matter in the universe, we have yet to positively identify it in any terrestrial experiment. If such matter is indeed a new particle, it may have a new interaction as well, carried by a dark counterpart to the photon. The DarkLight experiment proposes to search for such a beyond-the-standard-model dark photon through complete reconstruction of the final states of electron-proton collisions. In order to accomplish this, the experiment requires a moderate-density target and a very high intensity, low energy electron beam. Building on an initial beam test in 2012, the DarkLight collaboration began Phase I of the experiment with several weeks of beam time in the summer of 2016, using the Low Energy Recirculator Facility at Jefferson Lab. I will review the technical challenges of DarkLight's design, and discuss our multi-phase approach toward a full measurement, including our current status. [Preview Abstract] |
Saturday, January 28, 2017 10:57AM - 11:09AM |
B9.00002: A Calculation and Measurement of Radiative Moller Scattering at 100 MeV with DarkLight Charles Epstein A number of current experiments rely on precise knowledge of electron-electron (Moller) and positron-electron (Bhabha) scattering. Many of these experiments, which have lepton beams on atomic targets, use these QED processes as normalization. In other cases, such as DarkLight (at the Jefferson Lab ERL), with electron beams at relatively low energy (100 MeV) and very high power (1 Megawatt), Moller scattering and radiative Moller scattering have such enormous cross-sections that they produce extensive amounts of noise that must be understood. In this low-energy regime, the electron mass can also not be neglected. As a result, we have developed a new Monte Carlo event generator for the radiative Moller and Bhabha processes, extending existing soft-photon radiative corrections with new, exact single-photon bremsstrahlung calculations, and including the electron mass: PRD 94, 033004 (2016). DarkLight provides us a unique opportunity to study this process experimentally and compare it with our work. As a result, we are preparing a dedicated apparatus consisting of two magnetic spectrometers as part of the first phase of DarkLight in order to directly measure this process. An overview of the calculation and the status of the experiment’s construction will be presented. [Preview Abstract] |
Saturday, January 28, 2017 11:09AM - 11:21AM |
B9.00003: Internal gas target system for the DarkLight experiment Ivica Friscic The DarkLight experiment at Jefferson National Laboratory (JLab) will perform a search for a dark photon in the mass range from 10 to 100 MeV/c$^2$. The experimental design requires very high luminosity, but at the same time must keep the background rate as low as possible. Therefore, the experiment will use the 100 MeV electron beam from JLab's Low Energy Recirculator Facility (LERF) and a windowless gas target. In the summer of 2016 we deployed Phase 1A of this experiment, including a thin-walled, windowless target, using narrow apertures to restrict the flow of gas and aggressive pumping systems to reduce the pressure outside of the target region. Here we present the current design of the DarkLight internal gas target system, its performance during the 2016 summer beam tests, and future prospects. [Preview Abstract] |
Saturday, January 28, 2017 11:21AM - 11:33AM |
B9.00004: Fast Scintillating Paddles for DarkLight Daniel Palumbo The DarkLight experiment proposes to search for a dark photon in the 10-100 MeV mass range via its production in fixed-target electron-proton collisions. The experimental design is driven by the desire to detect the complete final state including the recoiling proton, while also sustaining a very high luminosity in order to search for this rare process. Although the final design of the DarkLight experiment calls for fully streamed detector readout, initial studies will rely on traditional, triggered approaches. In order to facilitate precision measurements at high rate, a fast, thin, finely-segmented trigger detector based on plastic scintillating paddles and custom amplifiers was developed. I will discuss this design and its performance in recent DarkLight beam studies, as well as the work we have done to develop detectors using individual scintillating fibers. [Preview Abstract] |
Saturday, January 28, 2017 11:33AM - 11:45AM |
B9.00005: Performance of GEM Detectors in the DarkLight Experiment at LERF Sahara Jesmin Mohammed Prem Nazeer The DarkLight experiment has been proposed to search for a heavy photon A' in the mass range of 10-100 MeV/c$^{2}$ produced in electron-proton collisions. Phase-I of DarkLight has started to take place in 2016 at the Low Energy Recirculator Facility (LERF) at Jefferson Lab. LERF delivered a 100 MeV electron beam onto a windowless hydrogen gas target. The phase-I detector tracks leptons inside the DarkLight solenoid with a set of Gas Electron Multiplier (GEM) detectors, combined with segmented scintillators for triggering. The GEM telescope consists of four $10 \times 10$ cm$^2$ triple layer GEM chambers with 2D readout strips, mounted in a slightly angled fixed frame about 12 cm tall. The GEM data are read out with analog pipeline front-end cards (APV-25) each of which can process 128 readout channels. Each GEM chamber has 250 channels for each coordinate axis, read out with two APVs on each side, resulting in 2000 readout channels for the GEM stack, processed by 16 APVs. One Multi Purpose Digitizer (MPD) module is used to read out all of the 16 APV-25 cards. The current run status of DarkLight experiment and the performance of GEMs in the experiment will be discussed. [Preview Abstract] |
Saturday, January 28, 2017 11:45AM - 11:57AM |
B9.00006: Searching for Dark Photons in the SeaQuest Experiment Michelle Mesquita de Medeiros The SeaQuest/E906 experiment at Fermilab was designed to study anti-quark distributions in the nucleon and nuclei by using Drell-Yan interactions between the 120 GeV proton beam from the Main Injector and different fixed targets. The front face of an iron magnet placed next to the targets serves as a beam dump while the muon pairs generated from these interactions are detected downstream. In the absorption process in the dump many particles are produced, including, possibly, dark photons through processes such as proton bremsstrahlung and eta decay. The dark photons could scape the dump and then decay into dimuons after travelling a certain distance determined by the coupling to the EM sector. The decay vertex is therefore significantly displaced, allowing for a very low background search. By detecting the dimuons with the SeaQuest spectrometer and analyzing their invariant mass distribution, one can search for signatures of these exotic processes. The present status of the dark photon search analysis will be presented. [Preview Abstract] |
Saturday, January 28, 2017 11:57AM - 12:09PM |
B9.00007: Sterile Neutrino Search with the PROSPECT Experiment Pranava Teja Surukuchi Venkata PROSPECT is a multi-phased short-baseline reactor antineutrino experiment with primary goals of performing a search for sterile neutrinos and making a precise measurement of $^{235}$U reactor antineutrino spectrum from the High Flux Isotope Reactor at Oak Ridge National Laboratory. PROSPECT will provide a model independent oscillation measurement of electron antineutrinos by performing relative spectral comparison between a wide range of baselines. By covering the baselines of 7-12 m with Phase-I and extending the coverage to 19m with Phase-II, the PROSPECT experiment will be able to address the current eV-scale sterile neutrino oscillation best-fit region within a single year of data-taking and covers a major portion of suggested parameter space within 3 years of Phase-II data-taking. Additionally, with a Phase-II detector PROSPECT will be able to distinguish between 3+1 mixing, 3+N mixing and other non-standard oscillations. In this talk, we describe the PROSPECT oscillation fitting framework and expected detector sensitivity to the oscillations arising from eV-scale sterile neutrinos. [Preview Abstract] |
Saturday, January 28, 2017 12:09PM - 12:21PM |
B9.00008: PROSPECT - A Precision Oscillation and Spectrum Experiment Xianyi Zhang PROSPECT, the PRecision Oscillation and SPECTrum Experiment, is a multi-phased short baseline reactor antineutrino experiment that aims to precisely measure the U-235 antineutrino spectrum and prob for oscillation effects involving a possible $\Delta$m$^2 \sim$\hspace{2pt}1\hspace{2pt}eV$^2$ scale sterile neutrino. In PROSPECT Phase-I, an optically segmented Li-6 loaded liquid scintillator detector will be deployed at at the baseline of 7-12m from the High Flux Isotope Reactor at the Oak Ridge National Laboratory. PROSPECT will measure the spectrum of U-235 to aid in resolving the unexplained inconsistency between predictive spectral models and recent experimental measurements using LEU cores, while the oscillation measurement will probe the best fit region suggested by global fitting studies within 1-year data taking. This talk will introduce the design of PROSPECT Phase-I, the discovery potential of the experiment, and the progress the collaboration has made toward realizing PROSPECT Phase-I. [Preview Abstract] |
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