Session E02: Neutrinos and Dark Matter

Recent Work on Detector R&D and Neutrino Cross Sections at MicroBooNE

MicroBooNE is an accelerator-based short-baseline neutrino experiment located in the Booster Neutrino Beamline at Fermilab. It is the most thoroughly studied Liquid Argon Time Projection Chamber, and has accumulated the largest statistics of neutrino interactions on argon to date. While the primary analysis goal of MicroBooNE is to address the anomalous electromagnetic excess observed by the MiniBooNE and LSND experiments, robust R&D and cross section programs provide important contributions to the international neutrino community. I will discuss recent developments and future plans of both the R&D and neutrino cross section programs, and explain their importance to LBNF/DUNE, the flagship domestic project of the US High Energy Physics program, which will come online later this decade.   

On Monitoring Purity in Liquid Argon Based Detectors

Liquid argon is being used as a target for neutrino interactions in current and future large-scale experiments. Charged particles ionize argon atoms in the liquid as they pass through and, in a Liquid Argon Time Projection Chamber (TPC), a strong electric field causes many of the resulting electrons to drift to the anode where they are detected. Electronegative impurities like oxygen and water can attach to the drifting electrons stopping them before they reach the anode. Low purity reduces the quality of reconstructed tracks, thus a dedicated method of measuring purity is essential to know the accuracy and reliability of a detector at any one time. In this talk, a purity monitor system tested by CSU will be discussed. It will measure the purity of liquid argon (electron lifetime) for the CSU `SingleCube' pixelated TPC. The purity monitor consists of an anode and cathode, an electric field to drift electrons, and a Xenon lamp that causes photo-electrons at a gold plate at the cathode. Current signals from the anode and cathode are sent to a charge integrating amplifier that produces amplified voltage output that can be used to access charge information before and after drifting. The charge information can then be used to provide a measure of purity in a detector.   

Reducing Neutrino Flux Uncertainties Using Hadron Production Measurements at NA61/SHINE

Neutrino flux uncertainties are frequently a leading systematic uncertainty in current day measurements of neutrino oscillation parameters at long-baseline experiments. These uncertainties can be constrained by hadron production measurements performed by the NA61/SHINE experiment at CERN's Super Proton Synchrotron. NA61/SHINE analyzes the interactions of charged hadrons with materials relevant to long-baseline experiments to measure the differential cross sections of particles that contribute to neutrino flux. This talk will review recent and ongoing measurements with thin and replica targets taken by NA61/SHINE for current and future neutrino beams.   

Progress on a cryoprobe atom extraction and spectroscopy system for barium tagging in nEXO

The nEXO experiment is a planned search for 0$\nu \beta \beta $ decay using a liquid xenon time projection chamber. In order to reduce background, several methods for identifying (or ``tagging'') the daughter barium are being developed. One potential method of barium tagging being investigated involves freezing the potential barium in solid xenon and then extracting the frozen sample by using a cryoprobe system. Matrix isolation spectroscopic techniques would then be used to identify the single barium within the frozen sample.[1] Progress is presented here on the development and testing of a cryoprobe spectroscopy system at CSU for freezing solid xenon (SXe) from liquid xenon, creation of Ba$^{\mathrm{+}}$ ions by laser ablation of Ba metal and capturing them in SXe on a window on the cryoprobe and spectroscopy of the Ba atoms and ions in the SXe. [1] Mong et al. 2015   

MADderHAT: Weighting the Model-Agnostic Dark Halo Analysis Tool

MADHAT (Model-Agnostic Dark Halo Analysis Tool) is a computational tool that processes data from Fermi Gamma-ray Space Telescope observations of dwarf galaxies and dwarf-like objects. MADHAT calculates the probability that some number of photons from each target object could be coming from non-standard astrophysics, including dark matter, and produces bounds on dark matter properties, such as the annihilation cross section and the decay rate. Unlike the majority of similar analyses, the bulk of MADHAT's analysis is model-independent. That is, MADHAT can be used to constrain the number of dark-matter-produced photons coming from a set of dwarf galaxies for any model of dark matter particle physics or astrophysics, including models of the more exotic variety. MADHAT version 1.0 weights all photons equally, irrespective of the sky region from which they come. Here, I report on progress implementing photon weights based on the dark matter and background expectations for each target object, which will improve sensitivity to dark matter models.