2019
List of past RPMs — 2019
The last twenty years have seen a spectacular improvement in our understanding of neutrino oscillations and neutrino physics in general. However, several experiments have shown some puzzling results which do not fit the standard three-flavor mixing scheme of neutrinos. In particular, the LSND and MiniBooNE experiments observed an excess of low-energy electron neutrinos, which could be interpreted as the signature of a fourth, non-weakly interacting, neutrino. The goal of the MicroBooNE experiment, a liquid argon time projection chamber currently running at Fermilab, is to assess the nature of this excess. In this talk the first automated electron neutrino search in a LArTPC will be presented. This result is the first step towards a measurement of the low-energy excess at MicroBooNE.
A large international collaboration has been formed to carry out an ambitious project to build the Deep Underground Neutrino Experiment (DUNE) for investigating fundamental questions in neutrino and proton decay physics. The DUNE far detector consists of four time-projection chambers (TPC) filled with 70,000 tons of liquid argon. It wil by far be the largest liquid argon neutrino experiment ever built. The ProtoDUNE experiment aims to validate the design and construction of the DUNE far detector by operating two kton-scale prototype detectors in a charged-particle beam at CERN. These two detectors will help assess different technologies for TPC ionization drift and readout (single and dual phase TPC) that are being considered in DUNE. In this talk I will discuss the challenges of building the large prototype detectors and present some preliminary results from operation of the single-phase ProtoDUNE detector.
Current and future galaxy surveys have the potential to transform our understanding of both galaxy formation and cosmology. The distribution of galaxies and matter on small, non-linear scales (~Mpc) holds the most statistical constraining power but is also the most challenging to model. In this talk, I will concentrate on three distinct probes on small scales: galaxy clustering, galaxy-galaxy lensing and satellite kinematics. I will present new measurements of the tension between clustering and lensing in the BOSS survey. The most promising explanations for this tension, baryonic feedback, assembly bias and cosmological parameters different from the Planck CMB constraints, are discussed. Furthermore, I will present an updated, more robust analysis to extract constraints on the galaxy-halo connection from satellite kinematics. The accuracy of this approach is tested using a large number of realistic mock catalogs and shown to yield unbiased, highly competitive constraints. I then apply this updated analysis to the SDSS survey and compare the inferences from satellite kinematics to those from previous studies. Finally, I will discuss future directions for modeling non-linear scales which will allow to unlock the full potential of upcoming surveys like DESI or LSST.
The measurement of the Yukawa coupling of the top quark and
the Higgs boson, namely the two most massive fundamental particles
observed so far, is a crucial piece for understanding the mechanism of
fermion mass generation. The most promising way to directly probe this
coupling is by measuring the Higgs boson production in association with
a top quark pair (ttH). ATLAS recently observed ttH production using
?s=13 TeV LHC pp collision data, exploiting several Higgs boson decay
channels. Current ttH results will be summarized in this seminar, and
prospects for future measurements will also be discussed.
Abstract:
Galaxy surveys and the study of the Large Scale Structure (LSS) have played an important role in establishing the standard cosmological model, LCDM, and will push the envelope of observational cosmology the next decades, thanks to experiments such as DESI and Euclid. In this talk, I will show how we can use LSS observations and techniques to address the tension in the Hubble constant, the origin of supermassive black holes and the nature of dark matter.
Furthermore, the ever larger volumes surveyed by next-generation galaxy surveys will enable access to the ultra-large scales, where signatures of General Relativity and inflation are significant. This will allow us to probe the nature of gravity and the very first instants of the Universe, but also requires a very specific methodology, which I will discuss during the talk.
CHIME is a new interferometric telescope at radio frequencies 400-800 MHz.
The mapping speed (or total statistical power) of CHIME is among the largest
of any radio telescope in the world, and the technology powering CHIME could
be used to build telescopes which are orders of magnitude more powerful.
Recently during precommissioning, CHIME started finding new fast radio
bursts (FRB’s) at an unprecedented rate, including a new repeating FRB.
Understanding the origin of fast radio bursts is a central unsolved problem
in astrophysics, and we anticipate that CHIME’s statistical power will play an
important role in solving it. In this talk, I’ll give a status update on CHIME, with
emphasis on FRB’s.
Mapping the polarized thermal dust emission from our galaxy is important for many fields of astrophysics, and recent observations reveal a complex network of filamentary structures which pervade the interstellar medium and molecular clouds, and are rich with prestellar cores. In the infrared and submillimeter, polarized dust emission traces magnetic field patterns which reveal key insights in to the physical processes which regulate the formation of filaments and stars, while for measurements of the cosmic microwave background (CMB) this dust emission is the dominant foreground.
The Next Generation Balloon-borne Large Aperture Submillimeter Telescope (BLAST-TNG) is a submillimeter mapping experiment planned for a long-duration balloon (LDB) flight from McMurdo Station, Antarctica during the 2018-2019 season. BLAST-TNG is the successor to the BLAST-Pol telescope which flew from Antarctica in 2010 and 2012, and produced degree-scale maps of molecular clouds at arcminute resolution. BLAST-TNG will detect submillimeter polarized interstellar dust emission, tracing magnetic fields in galactic molecular clouds. BLAST-TNG will be the first polarimeter with the sensitivity and resolution to probe the ~0.1 parsec-scale features that are critical to understanding the origin of structures in the interstellar medium. BLAST-TNG will also be able to make the deepest maps to date of the dust emission in the types of dark, diffuse regions of the sky favored by state of the art CMB polarization experiments. BLAST-TNG will probe angular scales not well-characterized to date, and explore correlations between diffuse dust emission and structures in the cold neutral medium at submillimeter wavelengths where the intensity of the thermal dust signal dominates.
In spite of a wide range of observational evidence, the mystery of dark matter is still present and dark matter remains to be directly detected. One of the most popular Dark Matter candidates is the Weakly Interacting Massive Particle (WIMP). In this talk, I present two results from the DarkSide-50 experiment for high-mass WIMP search and for low-mass WIMP search. In the low-mass WIMP search, there is an excess over the known background events at the small number of electrons region (Ne < 7). An updated study on this excess will be presented.
After the discovery of the Higgs boson, the future of high energy physics became a central question. There have been several proposals of future colliders which would continue the exploration of the high energy frontier beyond the reach of the LHC. Their fate could be determined in this couple of years. I will give an overview of the physics cases for these proposals, and offer my own perspective on the road ahead.
A precise prediction of the neutrino flux is a key ingredient for achieving the physics goals of accelerator-based neutrino experiments. In modern experiments, neutrino beams are created from the decays of secondary hadrons produced in hadron-nucleus interactions. Hadron production is the leading systematic uncertainty source on the neutrino flux prediction; therefore, its precise measurement is essential.
The NA61/SPS Heavy Ion and Neutrino Experiment (NA61/SHINE) is a fixed-target experiment at the CERN Super Proton Synchrotron which studies hadron production in hadron-nucleus and nucleus-nucleus collisions for various physics goals. For neutrino physics, light hadron beams (protons, pions, and kaons) are collided with a light nuclear target (carbon, aluminum, and beryllium) and spectra of outgoing hadrons are measured. In this talk, I will present recent results and ongoing analyses of hadron production measurements at NA61/SHINE for precise neutrino flux predictions in the T2K and Fermilab-based long-baseline neutrino experiments. I will also discuss the necessity and prospects of further hadron production measurements for the next generation neutrino experiments with NA61/SHINE beyond 2020, after the Long Shutdown 2 of the accelerator complex at CERN.
Measurements of the Cosmic Microwave Background (CMB) anisotropies and, more recently, of the distribution of galaxies at late times led us to the definition of a concordance cosmological model, the so called LCDM model. Despite its phenomenological success, several fundamental questions about the origin and fate of our Universe remain unanswered in the simplest LCDM scenario. What mechanism, if any, has set up the initial conditions of the Universe? What is nature of Dark Energy? What is the value of neutrinos masses, and are there any other light particles?
Several upcoming experiments, like DESI, LSST and Simons Observatory, promise to shed light on some of these misteries, but will still be very far from the cosmic variance limit.
In fact most of the observable volume of the Universe lives at redshift z>2, where observing galaxies at high number densities becomes increasingly more difficult.
A possible solution is offered by neutral hydrogen (HI), which is ubiquitous in our Universe at z<6. In emission, HI can be mapped using the infamous 21 cm line at radio frequencies.
In this talk, after summarizing the current status of 21 cm observations, I will present the science case for a Stage-II 21 cm experiment targeting the redshift range 2<z<6, and show it will dramatically improve our knowledge of DE and inflation, while keep reducing errorbars on other cosmological parameters.
Searches for high energy signatures from beyond the standard model physics have advanced greatly, but a lot of ground remains to be covered for soft, low energy signals. In the context of dark matter direct detection, future single-phonon detectors will be sensitive to dark matter with a mass as low as roughly 10 keV. In this regime, the conventional nuclear recoil picture no longer applies and new theoretical tools are needed to correctly calculate the scattering rate. I will discuss the prospects for detector concepts based on superfluid helium and polar material targets, where in the latter case we find a large daily modulation of the scattering rate.
New methods and novel strategies are needed in the search for physics beyond the Standard Model (BSM). Motivated by signals of lepton flavor universality violation in semileptonic B decays, I’ll discuss state-of-the-art theoretical developments and new model-independent theoretical tools that are required to self-consistently and efficiently classify these, or other, potential BSM effects within experimental analysis frameworks. I’ll then discuss the development, theory motivations and reach for a proposed subdetector at the LHCb experiment — CODEX-b — capable of competitively searching for decays-in-flight of exotic long-lived particles, which can be signals of a wide range of well-motivated BSM theories.
Neutrino oscillation measurements have shown that lepton flavor is not conserved, and that the standard model must be extended to include neutrino mass. Neutrino-less double beta decay measurements will help understand the nature and origin of neutrino mass, while searches for charged lepton flavor violation will probe whether there is additional flavor-related physics beyond the standard model.
The SNO+ experiment will employ 780 tons of liquid scintillator loaded with 1.3 tons of 130Te for a low-background and high-isotope-mass search for neutrino-less double beta decay. SNO+ will run in multiple phases with different target materials, allowing it to additionally study geo- and reactor neutrinos, solar neutrinos, and search for invisible modes of nucleon decay. First results from the SNO+ water phase will be presented. The Mu2e experiment will search for the charged-lepton flavor violating (CLFV) neutrino-less conversion of a negative muon into an electron in the field of a nucleus. Mu2e will improve the previous measurement by four orders of magnitude, reaching a 90% C.L. sensitivity to CLFV conversion rates of 8 × 10?17 or larger. The experiment is sensitive to a wide range of new physics at high mass scales, complementing direct searches at colliders. Mu2e is under design and construction at the Muon Campus of Fermilab; we expect to start taking physics data in 2023.
Abstract:
The Standard Model describes the building blocks of matter and their interactions. It has been tested extensively with experimental data and found to be incredibly successful in describing nature. Discovering the Higgs boson in 2012 at the LHC completed the picture of the SM. The LHC is at the forefront of directly searching for new physics which is Beyond-Standard-Model (BSM), and I will discuss searches for supersymmetric partners of the electroweak bosons, as well as measurement of an extremely rare process with three WWW bosons as stringent tests of the SM. I will also discuss the instrumentation which enables such studies. The discussion includes the recently completed CMS Phase-1 pixel upgrade, as well as the R&D studies towards solving the future trigger and computing challenges using innovative machine learning approaches in future high energy experiments.
In this talk, I will present various ways in which we can use galaxy redshift surveys to constrain fundamental physical models. This year the DESI experiment will launch, collecting a dataset of about 50 million galaxies and Quasars. Using observables like Baryon Acoustic Oscillations and Redshift-space distortions we can use this dataset to measure the sum of the neutrino masses and the number of neutrino species as well as test models of dark energy and modified gravity. Moreover, we can test models of the very early Universe (inflation) through primordial non-Gaussianity and primordial oscillations. The multitude of upcoming survey experiments (LSST, Euclid, WFIRST, DESI) offers exciting prospects to put the standard model of cosmology (LCDM) to the test.
Many new results from a wide range of particle physics experiments and
theoretical predictions were shown at the 54th Rencontres de Moriond.
On the experimental side, they included updated ATLAS/CMS analyses
(many using the full Run 2 dataset), probes CP-violation, new
experimental inputs to the muon g-2 prediction, updated neutrino
measurements, results from direct searches for Dark Matter, dynamics
in heavy ion collisions and many more. They were supplemented on the
theory side by higher orders calculations achieving new levels of
precision. We will present a biased selection of the most interesting
results from Moriond EW and QCD sessions.
ABSTRACT:
What is common among a magnet, a halibut, a rack of laundry, your heart on the left of your body, and the Higgs boson? The concept of spontaneous symmetry breaking is ubiquitous among many natural phenomena. I’ll describe the basic concept and its applications. In particular, the original concepts from Anderson, Nambu, Goldstone, and Higgs do not quite work in many systems that include a magnet on your fridge. I generalize the concept so that it is applicable to all known natural phenomena around us. I will also touch on recent related ideas on dark matter and dark energy.
Video:
There have now been several generations of wide-field mm-wave surveys, with several ongoing and upcoming very ambitious projects. We have already learned a great deal about the early universe and put strong constraints on particle physics extensions to the standard model, also collecting large catalogs of strong gravitational lens systems and massive clusters of galaxies, and learning a great deal about the growth of large scale structure in the universe. Ongoing and future experiments will continue to probe the early universe, collect larger catalogs of interesting lenses and clusters, and more carefully chart large scale structure, while also opening new windows on solar system science, transient events, and multi messenger astronomy. These surveys are more widely known as cosmic microwave background experiments.
The LHCb experiment has just discovered new narrow pentaquark states decaying to J/psi p, which shed more light into the nature of the J/psi p structures reported by LHCb in Lambda_b decays four years ago. We will describe these results in a broader context of experimental evidence for multiquark states with more than minimal quark content. Future experimental prospects will be outlined.
Recent measurements of observables involving the flavour changing neutral current transition b?s?+?? have shown an interesting pattern of tensions with respect to the predictions of the Standard Model (SM). However, the interpretation of these results is limited by our present understanding of the hadronic uncertainties affecting these predictions. Given the lepton-flavour-universal nature of the SM, observables such as RK=BR(B+?K+?+??)/BR(B+?K+e+e?), so-called Lepton Flavour Universality ratios, profit from large cancellation of the theory uncertainties and provide a very sensitive probe for physics beyond the SM.
The previous measurement of the ratio RK performed by the LHCb collaboration, using Run 1 data, found a value compatible with the SM expectation at the 2.6? level. In this seminar, a new measurement of RK at the LHCb experiment will be presented. The new measurement reanalyses the data recorded by LHCb during Run 1, and adds data collected during 2015 and 2016. The total dataset is double the size of that previously analysed.
The hypothesis of the existence of non-baryonic dark matter in our galactic halo is supported by all astrophysical observations performed from cosmological to local scales. The measurement of one clear experimental signal of this matter represents one of the most important challenges for physics today. The direct detection of an elastic collision with a target nucleus of a weakly interacting massive particle (WIMP), the most accepted candidate for such a matter, has to be discriminated from those produced by neutrons and neutrinos, which produce the same expected signal. The only non-ambiguous signature to be able to discriminate the WIMP events from neutrons-induced events is to correlate these elastic collisions in the detector with the relative motion of our Solar system with respect to the galactic halo. The measurement of thedirection of the nuclear recoil track in 3D of a few tens of keV is called directional detection. The directional detection opens a new field in cosmology: it brings the possibility to build a map of nuclear recoils exploring the galactic halo and gives access to a particle characterization of dark matter. The MIMAC (MIcro-tpc MAtrix of Chambers) collaboration has developed in the last years an original prototype detector based on the direct coupling of a pixelized Micromegas with a special developed fast self-triggered electronics showing the feasibility of a new generation of directional detectors. The flexibility of the MIMAC detector to change the nucleus target, changing its mass and spin, makes possible to adapt the search of candidates proposed by the large mass direct detection projects as LUX, Xenon1T, SCDMS or Edelweiss. In the next years, these large mass detectors will either detect some candidates or the neutrino background floor will limit them. In both cases a directional detector will be needed to confirm the galactic halo origin of such candidates or to go further the neutrino background. The MIMAC angular resolution measured coupling one of the chambers with COMIMAC, a dedicated facility developed allowing ionization quenching factor measurements and electron calibration, will be shown. The localization of the 3D track by the cathode signal will be described and the new possibilities open by this new directional detector in the neutron spectroscopy will be illustrated.
Measurements of the Cosmic Microwave Background (CMB) temperature anisotropies and E-mode polarization have proven to be essential to our understanding of early universe cosmology by providing independent and strong evidence in favor of the Lambda-CDM cosmological model. However, there is still untapped information in the CMB. Current-generation CMB experiments aim to measure the very faint B-mode polarization signal in order to find evidence of cosmic inflation and to measure the sum of the neutrino masses.
POLARBEAR-2 (PB-2) is a CMB polarization experiment located in northern Chile’s Atacama Desert at an altitude of 5,200 meters. PB-2 is currently operating with over 7,500 superconducting Transition Edge Sensor (TES) bolometers with a scheduled increase to over 22,000 TES bolometers in the next year. PB-2 uses Digital Frequency Division Multiplexed (DfMux) readout to combine the bias and readout lines for sets of forty detectors onto a single pair of conductors in order to reduce cost and cryogenic complexity.
Superconducting (TES) bolometers are the gold-standard technology for observing the CMB because they can be used to make photon noise limited measurements. This is why CMB experiments continue to increase their detector counts – to achieve higher sensitivity. However in order to achieve optimal sensitivity, the TES and multiplexing system must meet certain specifications. In this talk, I will describe the requirements imposed on the detectors and readout system and the measurements I have performed at the University of California San Diego to characterize the detectors and readout system of the first and second PB-2 cryogenic receivers.
The CMS detector is being upgraded for the phase two of the LHC, where a dataset with much larger integrated luminosity will precisely measure the Higgs boson couplings and extend new phenomena searches to cover challenging scenarios with large backgrounds. Collecting that larger dataset will require much higher instantaneous luminosity causing up to 200 additional proton-proton collisions in each crossing which complicate event reconstruction. A new detector system within this upgrade, the MIP Timing Detector, will provide precise time measurements with 30 to 50 ps resolution for each charged particle. This 4D tracking will resolve the collisions in both space and time, broadly improving the event reconstruction performance. I will describe the motivations for this new detector, its design, and recent progress.
QCD predicts a phase transition to quark gluon plasma. This plasma is now produced regularly in collisions of heavy nuclei at both RHIC and the LHC, and it exhibits remarkable properties. Its vanishingly small shear viscosity to entropy density ratio means that it ?ows essentially without internal friction, making it one of the most perfect liquids known. Quark gluon plasma is also very opaque to transiting strongly interacting particles. Determining the transport properties of quark gluon plasma is a key goal of current research, and jets of hadrons offer a promising probe. Howevere, it remains a mystery how this plasma emerges from cold, dense gluonic matter deep inside nuclei within 1 fm/c. Furthermore, properties of the cold QCD matter deep inside nuclei are unknown. I will discuss how a future electron-ion collider can help address these questions.
The CMS experiment has analyzed up to 140 fb-1 of pp collisions delivered by the LHC at 13 TeV. This data has allowed for improved precision in several aspects of Higgs-boson and electroweak physics and pushed the frontiers on searches for new resonances, long-lived particles and other phenomena. I will highlight some of the recent CMS results and prospects for the High-Luminosity running phase.
Quantifying how terrestrial systems respond to climate change and other perturbations is challenging due to the complexity of associated processes that occur from bedrock-to-canopy and from genome to watershed scales. This presentation will describe the development of several new approaches to help bridge these compartments and scales through integrating disparate geophysical, hydrological, geochemical and microbial datasets. A brief overview of the Earth and Environmental Sciences Area will first be provided to motivate the technical presentation. The presentation will subsequently describe the use of new geophysical characterization approaches in an Arctic tundra ecosystem, where increasing temperatures are thawing the permafrost, potentially leading to significantly increased production of greenhouse gasses. The development and testing of new methods to quantify the structure and function of a mountainous watershed in the Upper Colorado River Basin, where droughts and early snowmelt may influence downgradient water availability and water quality, will then be presented. The recent advances are leading to insights about how these systems function and respond to perturbations – from local scales where native processes occur toward watershed scales that are relevant for managing natural resources.
At present a process is ongoing in Europe to update the European Strategy of Particle Physics with respect to the previous update from May 2013. The process was started last year and is expected to end in May 2020. Major discussions of the scientific prospects of a wide variety of future projects took place during a symposium in Granada/Spain. In this talk I will explain the process and try to highlight the scientific opportunities discussed.
Conventional methods for searching for new physics at the LHC have mostly been “top-down”: starting from a specific model, searches are designed and optimized to have the best sensitivity to that model. Despite hundreds of conventional new physics searches at the LHC, none have turned up any hint of new physics. Maybe it’s time to admit that we don’t know what we’re looking for.
Breakthroughs in modern deep learning have the potential to revolutionize how we search for new physics at the LHC. In particular, techniques borrowed from unsupervised machine learning could enable us to search for new physics in a largely model-agnostic way. In this talk I will review some promising recent proposals in this direction. These proposed search strategies could complement more conventional methods by finding surprising signals that were not anticipated by any model, ensuring that we leave no stone unturned in the hunt for new physics at the LHC.
High-energy frontier in particle physics is going to enter into an era of precision studies after Run 3 at the LHC, with the increase of proton luminosity and upgraded detectors. This will pose a significant challenge to the event reconstruction and data analysis, where one has to look for (tiny) hints of new physics in a huge amount of collected data. Over the last few years quantum computing, in particular the hardware systems with superconducting qubits, has grown significantly, making a quantum computer with order of 50-100 qubits, called NISQ device, nearly in hand. This motivates an exploration of this new technology in high energy physics (HEP) experiments, aiming to identify interesting application of quantum algorithms to data analysis. In this talk, I will discuss about possible HEP applications of quantum computing and current status of those studies.
Abstract:
SPT-3G is a third-generation camera for the 10-meter diameter South Pole Telescope (SPT), which is designed to measure the cosmic microwave background (CMB). To achieve a high mapping speed, we have developed a new multichroic receiver with a total of 16,000 polarization-sensitive detectors. SPT-3G began a 6-year 1500 square degree survey in February 2018, which will produce measurements of CMB temperature and polarization anisotropies with an unprecedented combination of angular resolution and sensitivity. In this talk, I will summarize the instrument status and highlight the development of the most compact millimeter-wavelength Fourier transform spectrometer, which was used for SPT-3G and is also a prototype for the proposed PIXIE satellite. I will also discuss the science goals and current data analyses, with a focus on the gravitational lensing analysis using SPT-3G’s first-year data.
Abstract:
The Cosmic Microwave Background has played a central role for cosmology in the past few decades. From the very first detection of its temperature more than 50 years ago to the measurement of the temperature anisotropy, every step contributed to advancing our understanding of the fundamental laws that govern our Universe. One of the most ambitious targets of current and future experiments is the detection of the primordial polarized B-mode signal. This signal is a tracer of inflation and it is expected to be most visible at large angular scales.
I will review the current status of the search for B-modes focusing on one of the main challenges: instrumental systematic effects and strategies to keep them under control. In particular I will discuss the impact of band-pass uncertainty in the presence of Galactic foregrounds. I will describe a simulation procedure developed to study the induced bias into CMB polarization maps, and the recovered tensor-to-scalar ratio parameter. I will describe the connection between the simulation results and the instrumental parameters for a representative space mission, and define requirements to minimize the effect. Furthermore, I will introduce our current plan to develop a testbed, which we can use to address multiple systematic effects without waiting for the fully assembled instrument.
The required sensitivity for a definitive measurement of the B-mode signal is extremely challenging, and focal planes of experiments are growing in size to increase the optical throughput in order to meet the requirements. This will require extra efforts in designing, fabricating, and testing all telescope components; only through meticulous knowledge of the instrument and all its sub-systems, as well as a careful calibration, we will be able to reach this ambitious goal.
The 21 cm line from neutral hydrogen gas has many useful properties for mapping large volumes of the cosmos. These maps will give us a view of the Universe when the first luminous objects formed through gravity – the Cosmic Dawn and the Epoch of Reionization, and later, the post-Reionization Universe. They may even allow us to map the epoch before these luminous objects, the cosmic dark ages. The large volumes of these maps promise dramatic improvements in estimation of cosmological parameters. Data is flowing now from a new generation of radio telescopes optimized for this task. Unfortunately, the main challenge for all of them is that the astrophysical radio foregrounds are ~10,000 times brighter than the expected hydrogen signal. In this talk I will focus on current and planned efforts to use the new technique of` ‘hydrogen intensity mapping to make tomographic maps of the post-Reionization universe. In particular, I will describe the first measurements from an instrument in China, called the Tianlai (‘Cosmic Sound’) Pathfinder.
Abstract:
Direct detection experiments create the most radioactively quiet spots on earth, to reveal collisions between dark and ordinary matter. XENON1T, the most sensitive such experiment currently, will soon be succeeded by LZ and XENONnT. This talk highlights XENON1T’s recent light dark matter search results, and modern analysis techniques — full online processing, and tensorflow-based profile likelihoods — to boost the physics reach of future direct detection experiments and other rare-event searches.
Abstract:
Liquid xenon (LXe) is employed in a number of current and future detectors for rare event searches. In this talk, I will present the latest results from EXO-200, which searched for neutrinoless double beta decay (0???) in Xe-136 between 2011 and 2018. I will also present a measurement of the absolute scintillation and ionization response generated by MeV energy gamma sources over a range of electric fields in EXO-200. These measurements are useful for simulating the performance of future 0??? detectors employing LXe, such as nEXO, which is a next generation 0??? experiment using Xe-136 aiming to reach a half-life sensitivity ~10^28 years. nEXO will require ultra-low radioactivity, high-speed cabling to carry digital signals from in-LXe electronics. I will describe the development of high-bandwidth digital cable prototypes with sufficiently low radioactivity for use in the experiment. While designed specifically for nEXO, the demonstration of radiopure high-bandwidth cabling and interconnection techniques is relevant for many next-generation rare-event searches with large channel counts and high-speed digital electronics.
The Cosmology Large Angular Scale Surveyor (CLASS) aims to characterize the primordial gravitational waves at the level of tensor-to-scalar ratio of 0.01, and make a cosmic-variance-limited measurement of the optical depth to reionization. CLASS is an array of four telescopes that surveys 70% of the microwave sky from the Atacama Desert at 40, 90, 150, and 220 GHz frequency bands. A unique combination of large sky coverage, rapid front-end polarization modulator, broad frequency coverage, and background-limited detectors enables CLASS to characterize the B-mode and E-mode power spectra on both the reionization and recombination scales. The detector arrays for all four CLASS telescopes contain smooth-walled feedhorns that couple to transition-edge sensor bolometers through planar orthomode transducers fabricated on mono-crystalline silicon. In this talk, I will give an overview of the design and performance of the CLASS detectors and provide an update on the current status of CLASS telescopes.