Bulletin of the American Physical Society
APS April Meeting 2017
Volume 62, Number 1
Saturday–Tuesday, January 28–31, 2017; Washington, DC
Session J9: Dark Matter with Xenon |
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Sponsoring Units: DPF Chair: Bob Tschirhart, FermiLab Room: Roosevelt 1 |
Sunday, January 29, 2017 10:45AM - 10:57AM |
J9.00001: Measurement of Low Energy Electronic Recoil Response and Electronic/Nuclear Recoils Discrimination in XENON100 Jingqiang Ye The XENON100 detector uses liquid xenon time projection chamber to search for nuclear recoils(NR) caused by hypothetical Weakly Interacting Massive Particles (WIMPs). The backgrounds are mostly electronic recoils(ER), thus it's crucial to distinguish NR from ER. Using high statistical calibration data from tritiated methane, AmBe and other sources in XENON100, the ER/NR discrimination under different electric fields are measured. The Photon yield and recombination fluctuation of low energy electronic recoils under different fields will also be presented and compared to results from NEST and other experiments, which is crucial to understanding the response of liquid xenon detectors in the energy regime of searching dark matter. [Preview Abstract] |
Sunday, January 29, 2017 10:57AM - 11:09AM |
J9.00002: Search for Periodic Rate Variations in XENON100 and Comparison with DAMA/LIBRA Annual Modulation Qing Lin Three Scientific runs of XENON100 data accumulated from January 2010 to January 2014 are analyzed to search for electronic recoil event rate modulation signatures. An improved understanding of the detector stability and background has been achieved in this updated analysis. A profile likelihood method, which incorporates the improved detector stability and background model, is used to search for periodical signatures in the XENON100 electronic recoil events. The new results of these studies and a comparison with the DAMA/LIBRA annual modulation will be presented. [Preview Abstract] |
Sunday, January 29, 2017 11:09AM - 11:21AM |
J9.00003: The XENON1T Dark Matter Experiment Patrick de Perio Recent results and status of the XENON1T direct dark matter detector will be presented. XENON1T is a two-phase xenon TPC using 248 low radioactivity PMTs to detect scintillation signals in a 2-ton active liquid xenon target. The detector has been fully operational at the Laboratori Nazionale del Gran Sasso since May 2016, with continuously improving xenon purity and reduction of the internal Kr-85 background source. This talk will summarize the detector performance, calibration, and background studies, discussed in more detail in the following XENON1T talks, which are paving the way towards the world's most sensitive dark matter search. [Preview Abstract] |
Sunday, January 29, 2017 11:21AM - 11:33AM |
J9.00004: The Electron Recoil Response of the XENON1T Dark Matter Experiment Evan Shockley XENON1T employs a two-phase xenon TPC to search for dark matter by detecting scintillation light produced by nuclear recoils in a 2 ton active volume of liquid xenon. ~However, nuclear recoils are not the only recoils that can occur since radiogenic electronic recoils are possible. ~Our only way of differentiating nuclear and electronic recoils is by comparing the relative fraction of scintillation (S1) and ionization (S2) signals. ~For the first Science Run of XENON1T, we must understand the response of our detector to S1 and S2 signals at the low keV energies where dark matter will present itself. ~Therefore, I will be discussing the current understanding of our signal and detection mechanisms at these energies. ~This work includes work using sources such as the Rn220 technique developed by XENON collaborators for understanding our rejection of electronic recoils. [Preview Abstract] |
Sunday, January 29, 2017 11:33AM - 11:45AM |
J9.00005: The Low-Energy Background in XENON1T Fei Gao, Alec Stein The XENON1T dark matter direct-detection experiment looks for hypothetical Weakly Interacting Massive Particles (WIMPs). WIMPs are expected to scatter off xenon nuclei at low energies, so understanding the low-energy background of the detector is crucial. In XENON1T, the background in the WIMP search region is due to radioactive decays stemming from the detector construction materials and impurities in the xenon itself. We show that our predicted low-energy background rate of $\sim 10^{-4} \text{events}\cdot\text{kg}^{-1}\cdot\text{day}^{-1}\cdot\text{keV}^{-1}$ matches XENON1T's design goals and is in agreement with the data taken during the commissioning of the detector. [Preview Abstract] |
Sunday, January 29, 2017 11:45AM - 11:57AM |
J9.00006: Purification for the XENONnT dark matter experiment Ethan Brown The XENON1T experiment uses 3.5 tons of liquid xenon in a cryogenic detector to search for dark matter. Its upgrade, XENONnT, will similarly house 7.5 tons of liquid xenon. Operation of these large detectors requires continual purification of the xenon in an external purifier, and the need for less than part per billion level oxygen in the xenon, coupled with the large quantity of xenon to be purified, places high demands on the rate of flow through this purification system. Building on the success of the XENON10 and XENON100 experiments, XENON1T circulates gaseous xenon through heated getters at a rate of up to 100 SLPM, pushing commercial pumps to their limits moving this large quantity of gas without interruption for several years. Two upgrades are considered for XENONnT. A custom high-capacity magnetic piston pump based on the one developed for the EXO200 experiment has been scaled up to support the high demands of this much larger experiment. Additionally, a liquid phase circulation and purification system that purifies the cryogenic liquid directly is being developed, which takes advantage of the much smaller volumetric flow demands of liquid relative to gas. The implementation of both upgrades will be presented. [Preview Abstract] |
Sunday, January 29, 2017 11:57AM - 12:09PM |
J9.00007: The XENONnT Dark Matter Experiment Elena Aprile With XENON1T ready to search for dark matter with the highest sensivity of any experiment to-date the XENON collaboration started to secure funding and resources to upgrade the detector by the end of 2018- phase which we refer to as XENONnT. The XENONnT experiment will utilize the already-built-and-tested XENON1T infrastructures, such as the cryogenic system, Kr distillation system and Xe storage and recovery system, with the main upgrade of the time projection chamber (TPC). The upgraded XENONnT detector will be filled with 7.5-ton ultra-pure liquid xenon, tripling the active liquid xenon target mass of XENON1T. About 500 low-radioactive three-inch R11410 PMTs will be used. Background from internal sources such as radon will be reduced. It will enable another order of magnitude improvement in dark matter search sensitivity compared to that of XENON1T, or accumulate statistics if a positive dark matter signal is observed by XENON1T. The detailed TPC upgrade plan, the background control and reduction techniques, the predicted sensitivity reach will be presented. [Preview Abstract] |
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