Bulletin of the American Physical Society
APS April Meeting 2019
Volume 64, Number 3
Saturday–Tuesday, April 13–16, 2019; Denver, Colorado
Session J09: Sub-GeV Dark Matter |
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Sponsoring Units: DPF Chair: Bertrand Echenard, Caltech Room: Sheraton Governor's Square 11 |
Sunday, April 14, 2019 1:30PM - 1:42PM |
J09.00001: The Heavy Photon Search Experiment Matthew R Solt The Heavy Photon Search experiment searches for an electro-produced dark photon using an electron beam provided by CEBAF at the Thomas Jefferson National Accelerator Facility. HPS has successfully completed two engineering runs. In 2015 using a 1.056 GeV, 50 nA electron beam, 1.7 days (10 mC) of data was obtained and 5.4 days (92.5 mC) of data was collected in a run in 2016 using a 2.3 GeV, 200 nA electron beam. In addition, HPS will complete its first physics run in the summer of 2019. HPS looks for dark photons through two distinct methods – a resonance search in the e+e invariant mass distribution above the large QED background (large dark photon-SM particles coupling region) and a displaced vertex search for long-lived dark photons (small coupling region). Both analysis are complete for the 2015 engineering run and demonstrate the full functionality of the experiment that will probe hitherto unexplored parameter space with future, higher luminosity runs. Results from the 2015 dataset with emphasis on the displaced vertex search will be presented as well as an update on 2016 analysis and preparations for 2019 physics run. |
Sunday, April 14, 2019 1:42PM - 1:54PM |
J09.00002: Search for dark matter in models with a very light Z’ Evan A Koenig We present a search for the unique signature of dark matter production using a few GeV-scale Z’ boson, using the Compact Muon Solenoid (CMS) detector at the Large Hadron Collider (LHC). In this model, dark matter produced in proton-proton collisions, radiates a light Z’. Due to the large mass difference between the Z’ and the dark matter, this radiated Z’ is boosted. The boosted Z’ decays manifests as a thin low-multiplicity jet. The two main backgrounds in this study, are jets produced in association with W and Z bosons. The normal quark and gluon jets in these events on occasion fragment anomalously, resulting in low multiplicity jets. |
Sunday, April 14, 2019 1:54PM - 2:06PM |
J09.00003: Constraining Dark Matter with Cosmic Ray Interactions Christopher Cappiello, John F Beacom The bulk of the dark matter in the galaxy is believed to have velocity of order several hundred km/s. However, it has recently been shown that cosmic ray collisions with dark matter may accelerate a small fraction of the galactic dark matter to much higher velocities. This boosted dark matter would transfer far more energy to target nuclei or electrons in a detector than it would if it were traveling at the typical dark matter speed in the galaxy. This has recently been used to place constraints on low-mass dark matter, to which direct detection experiments are usually blind because of their threshold energy. We explore various avenues to improve the sensitivity of these studies. |
Sunday, April 14, 2019 2:06PM - 2:18PM |
J09.00004: Latest Constraints on Millicharged Particles Using ArgoNeuT Ivan Lepetic Millicharged particles (mCPs) are theoretical particles with fractional electric charge, which could constitute part of the dark matter present in the Universe and can naturally arise in dark sectors with U(1)' gauge symmetries. We report the latest constraints to the parameter space of mCPs using data from ArgoNeuT, a 0.24 ton Liquid Argon Time Projection Chamber (LArTPC), with a novel phenomenoglical proposal of aligning doublet hits. ArgoNeuT was placed in the Neutrinos at the Main Injector (NuMI) neutrino beamline at Fermilab from 2009-2010. The 120 GeV proton beam which produced the neutrinos could also produce a large flux of mCPs which would interact in ArgoNeuT. In addition to setting limits, we describe the manner in which mCPs would be detected in LArTPCs. |
Sunday, April 14, 2019 2:18PM - 2:30PM |
J09.00005: Search for sub-GeV Dark Matter with MiniBooNE Remington T Thornton Cosmological observations indicate that our universe contains dark matter, yet we have no measurements of its microscopic properties. Direct detection experiments search for a nuclear recoil interaction and have a low-mass sensitivity edge of order 1 GeV. A path to detect dark matter with mass below 1 GeV is to search for boosted dark matter begin produced at accelerators. Neutrino detectors are already sensitive to dark matter interactions because of the similarity of the dark matter and neutrino signatures in the detector. The MiniBooNE experiment, located at Fermilab on the Booster Neutrino Beamline, has searched for dark matter produced from protons interacting in the beam-dump using various interaction channels. This talk will go over the analysis and results of this search. |
Sunday, April 14, 2019 2:30PM - 2:42PM |
J09.00006: Low-mass Dark Matter Search Using Ionization Signals in LUX Peter Sorensen LUX (Large Underground Xenon) is a retired, 250 kg, liquid xenon, direct dark matter detection experiment that has published three, previously world leading limits on the spin-independent cross section for WIMP-nucleon scattering in the 5-1000+ GeV mass range. LUX was successful thanks to a two channel readout of both scintillation (S1) and ionization (S2) that allows for event position reconstruction and, thus, rejection of backgrounds occurring primarily at the edges of the xenon volume. However, because the S2 signal is detected with approximately ⨉10 greater efficiency than the S1 signal, xenon detectors can lower their energy threshold and look for the nuclear recoils of lower mass dark matter particles by letting go of the requirement of an S1. In this type of analysis, additional background events are expected, because the reconstructed z-coordinate is no longer accessible. In addition to this expected increase, we have found an excess of background events emitted by the electrodes. In this talk, a new mitigation strategy for electrode events is outlined and the latest results from LUX’s ionization-only low-mass dark matter analysis are presented. |
Sunday, April 14, 2019 2:42PM - 2:54PM |
J09.00007: Recent progress on a search for sub-GeV dark matter in the complete LUX exposure Junsong Lin Recent studies suggest that by using the dark matter - nucleus inelastic scattering channel, dual-phase xenon time projection chambers can be sensitive to sub-GeV dark matter. Sub-GeV dark matter is difficult to probe, because of the small energy transfer in dark matter - nucleus elastic scattering and the finite energy threshold of the detector. Bremsstrahlung photon emissions and electron emissions from the Migdal effect, two effects in the inelastic scattering channel, are used to circumvent this difficulty. This analysis utilizes both the scintillation (S1) and ionization (S2) signals in the complete LUX exposure data. Recent progress on this analysis is presented, building on the search result in the LUX 2013 data. |
Sunday, April 14, 2019 2:54PM - 3:06PM |
J09.00008: The Snowball Chamber: Using Supercooled Water to Search for Low-Mass Dark Matter Matthew M Szydagis, Alvine C Kamaha, Corwin Knight, Cecilia Levy, Joshua E Martin The cloud and bubble chambers have historically been used for particle detection, capitalizing on supersaturation and superheating respectively. We present now on the snowball chamber, which utilizes a supercooled liquid. In our prototype, an incoming particle triggered crystallization of purified water. We demonstrate that water is supercooled for a significantly shorter time with respect to control data in the presence of AmBe and 252Cf neutron sources. A greater number of multiple nucleation sites are observed as well in neutron calibration data, as in a PICO bubble chamber. Similarly, gamma calibration data indicate a high degree of insensitivity to electron recoils inducing the phase transition, making this detector potentially ideal for dark matter searches seeking nuclear recoil alone. We will explore the possibility of using this new technology for that, updating the community on new results achieved since last year's APS meeting (April 2018). |
Sunday, April 14, 2019 3:06PM - 3:18PM |
J09.00009: Low Energy Nuclear Recoil Calibration with Neutron Capture Nicholas Mast, Matthew Fritts, Anthony Nicholas Villano Ongoing experiments are searching for dark matter or coherent neutrino scattering signals via |
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