INPA

Special INPA SEMINAR - Karthik Ramanathan (University of Chicago)
2020-02-04 11:00 - 12:00 (America/Los_Angeles) | 50A-5132- Sessler, 50A-5132 Sessler Conference Room, CA
Speaker: Karthik Ramanathan (University of Chicago)

Title: Dark Matter Taking Selfies: The DAMIC Experiment

Abstract: The DAMIC (Dark Matter in CCDs) experiment uses silicon charge-coupled devices (CCDs), traditionally employed for imaging purposes, to detect potential ionization signals from dark matter interactions. These approx. mm thick devices feature an impressively low leakage current (< 10-21 A/cm2) and a very low energy threshold (40 eVee), making them ideal low-mass dark matter detectors. In addition, their unique spatial resolution provides for effective identification and mitigation of environmental backgrounds. In this talk, I will highlight recent dark matter-electron scattering limits from the experiment at SNOLAB, discuss the kg-size next generation DAMIC-M detector funded for operation, and show results from “Skipper”instrumented CCDs – a novel readout technique that allows for counting of individual charges, with a demonstrated resolution of 0.07 e-, which ushers in a new era of sensitivity to low-energy interactions.

INPA Seminar - Harikrishnan Ramani (LBNL)
2020-02-07 12:00 - 13:00
Speaker: Harikrishnan Ramani (LBNL)

Title: Nuclear Isomers as Dark Matter accelerators
Abstract: Weak-scale dark matter particles, in collisions with nuclei, can mediate transitions between different nuclear energy levels. In particular, owing to sizeable momentum exchange, dark matter particles can enable de-excitation of nuclear isomers that are extremely long lived with respect to regular radioactive decays. In this paper, we utilize data from a past experiment with $^{rm 180m}$Ta to search for $gamma$-lines that would accompany dark matter induced de-excitation of this isomer. Non-observation of such transitions above background yields the first direct constraint on the lifetime of $^{rm 180m}$Ta against DM-initiated transitions: $T_{1/2}>1.3times 10^{14}$~a at 90% C.I. Using this result, we derive novel constraints on dark matter models with strongly interacting relics, and on models with inelastic dark matter particles. Existing constraints are strengthened by this independent new method. The obtained limits are also valid for the Standard Model $gamma$-decay of
uc{Ta}{rm 180m}.

Speaker: Vishal Gajjar (UC Berkeley)
2020-02-14 12:00 - 13:00
Title: Breakthrough Listen’s search for intelligent life in the Universe

Abstract: The discovery of the ubiquity of habitable extrasolar planets, combined with revolutionary advances in instrumentation and observational capabilities, have ushered in a renaissance in the millennia-old quest to answer our most profound question about the Universe and our place within it – Are we alone? The Breakthrough Listen Initiative announced in July 2015 as a 10-year 100M USD program is the most comprehensive effort in history to quantify the distribution of advanced, technologically capable life in the universe. In this talk, I outline the status of the on-going observing campaign with our primary observing facilities, as well as planned activities with these instruments over the next few years. I will also talk about collaborative facilities which will conduct searches for technosignatures in either primary observing mode or commensally. I will highlight some of the novel analysis techniques we are bringing to bear on multi-petabyte data sets, including machine learning tools we are deploying to search for a broader range of technosignatures than was previously possible. https://arxiv.org/abs/1907.05519

Special INPA SEMINAR - Wouter Van De Pontseele (Harvard/Oxford)
2020-02-19 15:30 - 16:30
Speaker: Wouter Van De Pontseele (Harvard/Oxford)

Title: The MicroBooNE Neutrino Experiment at Fermilab

Abstract: MicroBooNE is a liquid argon time projection chamber in the Booster Neutrino Beam at Fermilab. The technology provides high-resolution imaging of neutrino interactions leading to low-threshold event reconstruction with full angular coverage. As such, this is an ideal place to probe neutrino-argon interactions in the hundreds-of MeV to few-GeV energy range. This talk presents a start-to-end overview demonstrating the physics capabilities of the detector. I will talk about cosmic ray measurement and characterisation, our dominant background.
Furthermore, I will describe the flavour-agnostic neutrino pre-selection, based on the combination of the charge collected by the TPC and the optical information form the PMT system. An overview of recent measurements of neutrino interactions in MicroBooNE, including inclusive charged-current interactions, will be given. I will conclude summarising the ongoing efforts towards our first low-energy-excess results, demonstrating our capability to identify electron neutrinos.

INPA Seminar - Chiara Capelli (University of Zurich)
2020-02-21 12:00 - 13:00
Speaker: Chiara Capelli (University of Zurich)
Title: Data analysis at high-energies for the XENON1T experiment and light calibration system of XENONn
Abstract: The XENON1T experiment searches for Weakly Interacting Massive Particles (WIMPs) with a dual-phase xenon Time Projection Chamber (TPC). To extend its physics reach, the efforts of the XENON collaboration are directed toward exploring other detection channels. For this purpose, considerable work on the signal reconstruction and data analysis has been done to extend the available energy range up to 3\,MeV, two orders of magnitude higher than the standard WIMP analysis. This would allow one to search for the neutrinoless double beta decay (0$
ubetabeta$) of $^{136}$Xe, which is fundamental to probing the Majorana nature of neutrinos and solving the hierarchy problem. The achievements and future prospects for the high-energy analysis with dual-phase TPCs will be presented. Furthermore, the upcoming XENONnT experiment, an upgrade of XENON1T with a larger TPC and reduced background, is expected to start taking data in 2020. Its main goal is to increase the sensitivity to WIMPs by an order of magnitude compared to the current best limit, as well as improving the search for 0$
ubetabeta$. An overview of the new systems, with attention on the light calibration of the 494 photomultiplier tubes (PMTs) will be also presented.

Special INPA Seminar – Gulden Othman (University of North Carolina)
2020-02-24 11:00 - 12:00
Speaker: Gulden Othman (University of North Carolina)
Title: CAGE Scanner: Investigating Surface Backgrounds in HPGe Detectors for Neutrinoless Double-Beta Decay Searches
Abstract: A potential source of problematic backgrounds in a ton-scale 76Ge-based neutrinoless double-beta decay (0nuBB) program may arise from particle interactions occurring near the surfaces of high purity germanium (HPGe) detectors. The Collimated Alphas, Gammas, and Electrons scanner (CAGE) is a test stand that allows for in-depth studies of surface events by using vacuum-side, collimated radiation sources to characterize the response of HPGe detectors to radiation at specific locations on the detector surface. LEGEND is a search for 0nuBB in the 76Ge isotope that will begin operation of a 200 kg array in 2021, with a plan to scale up to 1000 kg of 76Ge-enriched HPGe detectors in a phased approach. In order to reach LEGEND-1000’s goal of a half-life sensitivity >10^28 years, understanding and discriminating against backgrounds from surface events is essential. I will motivate the design and current status of CAGE in the context of LEGEND as we begin characterizing the response of two detector geometries that will be used in LEGEND to surface alpha interactions.
