LBNL Physics Division Research Progress Meetings

Qing Shilo Xia (Yale) "Hunting for neutrinoless double beta decay with liquid xenon detectors"
2019-12-12 16:00 - 17:00 UTC | HYBRID 50A-5132 (Sessler Conference Room), https://lbnl.zoom.us/j/91782268585, 50A-5132
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 (0υββ) 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 0υββ detectors employing LXe, such as nEXO, which is a next generation 0υββ 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.

Jelle Aalbers (Stockholm U) "XENON1T: When All Other Lights Go Out"
2019-12-10 16:00 - 17:00 UTC | 50B-4205
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.

Peter Timbie (UW-Madison) "21cm Intensity Mapping: A New Cosmological Tool?"
2019-12-05 16:00 - 17:00 UTC | HYBRID 50A-5132 (Sessler Conference Room), https://lbnl.zoom.us/j/91782268585, 50A-5132
ABSTRACT:
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.

Tommaso Ghigna (Oxford U.) "The quest for CMB B-modes and the challenge of controlling systematic effects"
2019-12-03 16:00 - 17:00 UTC | HYBRID 50A-5132 (Sessler Conference Room), https://lbnl.zoom.us/j/91782268585, 50A-5132
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.

Reserved
2019-11-28 16:00 - 17:00, 2019-11-26 16:00 - 17:00, 2019-11-19 16:00 - 17:00, 2019-11-14 16:00 - 17:00, 2019-11-12 16:00 - 17:00, 2019-11-07 16:00 - 17:00, 2019-11-05 16:00 - 17:00 UTC | HYBRID 50A-5132 (Sessler Conference Room), https://lbnl.zoom.us/j/91782268585, 50A-5132

Zhaodi Pan (U. Chicago) "Instrument and science for the SPT-3G cosmic microwave background receiver"
2019-11-21 16:00 - 17:00 UTC | HYBRID 50A-5132 (Sessler Conference Room), https://lbnl.zoom.us/j/91782268585, 50A-5132
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.

Koji Terashi (CERN) " Quantum Computing and Possible Application to High-Energy Physics"
2019-10-31 16:00 - 17:00 UTC | HYBRID 50A-5132 (Sessler Conference Room), https://lbnl.zoom.us/j/91782268585, 50A-5132
Abstract:
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.

David Shih (Rutgers/LBNL) "Searching for the Unexpected at the LHC with Unsupervised Machine Learning"
2019-10-22 16:00 - 17:00 UTC | HYBRID 50A-5132 (Sessler Conference Room), https://lbnl.zoom.us/j/91782268585, 50A-5132
ABSTRACT:
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.

Patrick de Perio (Triumf) " CP Violation in Neutrino Oscillations with Hyper-Kamiokande
2019-10-01 16:00 - 17:00 UTC | HYBRID 50A-5132 (Sessler Conference Room), https://lbnl.zoom.us/j/91782268585, 50A-5132
Abstract: We live in a matter dominated world, so where did all the antimatter go? The Hyper-Kamiokande (Hyper-K) experiment in Japan is trying to detect charge-parity violation (CPV) in neutrino oscillation, which could help explain this phenomenon. As the successor of the T2K experiment, Hyper-K produces a beam of neutrinos or antineutrinos directed towards a far detector 295 km away, which is about 8 times bigger than the current far detector, Super-Kamiokande, a water Cherenkov detector. With an expected statistical uncertainty of 3% for both neutrinos and antineutrinos, Hyper-K aims to tease out the small neutrino/antineutrino oscillation difference. In this talk, I will discuss our efforts to control systematic errors at an unprecedented level, arising from 1) neutrino beam production, 2) neutrino interaction modeling, and 3) water Cherenkov detector calibration.

Beate Heinemann (DESY) "European Strategy for Particle Physics Update 2020: Status and Prospects"
2019-09-19 16:00 - 17:00 (America/Los_Angeles) | HYBRID 50A-5132 (Sessler Conference Room), https://lbnl.zoom.us/j/91782268585, 50A-5132
ABSTRACT:
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.

David Schlegel (LBNL) "TBA"
2019-09-05 16:00 - 17:00 (America/Los_Angeles) | HYBRID 50A-5132 (Sessler Conference Room), https://lbnl.zoom.us/j/91782268585, 50A-5132
ABSTRACT:

Susan Hubbard (ESA, LBNL) "Imaging Watershed Behavior & Overview of the Earth and Environmental Sciences Area"
2019-08-29 16:00 - 17:00 (America/Los_Angeles) | HYBRID 50A-5132 (Sessler Conference Room), https://lbnl.zoom.us/j/91782268585, 50A-5132
ABSTRACT:
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.

Bruno Lenzi (IRFU, Saclay France)"Recent results of the CMS experiment at LHC"
2019-08-06 16:00 - 17:00 (America/Los_Angeles) | HYBRID 50A-5132 (Sessler Conference Room), https://lbnl.zoom.us/j/91782268585, 50A-5132
Abstract:
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.

Barbara Jacak (LBNL/UCB) "The Mysteries of QCD Matter - Hot and Cold"
2019-08-01 16:00 - 17:00 (America/Los_Angeles) | HYBRID 50A-5132 (Sessler Conference Room), https://lbnl.zoom.us/j/91782268585, 50A-5132
ABSTRACT:
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 ﬂows 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.

David Stuart (UCSB) "Charged particle timing with 30-50 ps resolution in CMS for the high luminosity LHC upgrade"
2019-07-30 16:00 - 17:00 (America/Los_Angeles) | HYBRID 50A-5132 (Sessler Conference Room), https://lbnl.zoom.us/j/91782268585, 50A-5132
ABSTRACT:
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.

Tucker Elliott (UCSD) "Characterization of Multiplexed Transition Edge Sensor Bolometers for the POLARBEAR-2 Cosmic Microwave Background Experiment"
2019-06-20 16:00 - 17:00 (America/Los_Angeles) | HYBRID 50A-5132 (Sessler Conference Room), https://lbnl.zoom.us/j/91782268585, 50A-5132
ABSTRACT:
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.

Daniel Santos (LPSC) "Directional Direct Dark Matter Detection and Neutrino Spectroscopy with MIMAC"
2019-06-18 16:00 - 17:00 (America/Los_Angeles) | HYBRID 50A-5132 (Sessler Conference Room), https://lbnl.zoom.us/j/91782268585, 50A-5132
ABSTRACT:

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.

Nathan Jurek (U. Oxford) "Observation of CP violation in charm decays (and more charming topics)"
2019-06-06 16:00 - 17:00 (America/Los_Angeles) | HYBRID 50A-5132 (Sessler Conference Room), https://lbnl.zoom.us/j/91782268585, 50A-5132
Precision measurements of the violation of charge-parity (CP) symmetry are crucial for testing the Standard Model and are sensitive probes for new physics contributions. While CP violation has been well-established by several different experiments in the decays of mesons containing strange and bottom quarks, searches for CP violation in the decays of charm mesons had until recently come up empty-handed. Thanks to its unprecedentedly large samples of charm mesons, the LHCb collaboration has succeeded in observing CP violation in the charm sector for the first time via a time-integrated analysis of D0→K−K+ and D0→π−π+ decays. These results will be presented, along with recent time-dependent measurements which help constrain additional sources of CP violation in neutral charm mesons. Finally, projections of future prospects in charm physics will be given.

Paula Alvarez Cartelle (Imperial College London) “Search for lepton flavour universality violation in B+→K+ℓ+ℓ− decays at LHCb”
2019-05-28 16:00 - 17:00 (America/Los_Angeles) | HYBRID 50A-5132 (Sessler Conference Room), https://lbnl.zoom.us/j/91782268585, 50A-5132
Abstract:
“Recent measurements of observables involving the flavour changing neutral current transition b→sμ+μ− 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+μ+μ−)/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 2.6σ 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.”

Tomasz Skwarnicki (Syracuse) "Observation of New Pentaquark States and Other Exotic Hadrons"
2019-05-16 16:00 - 17:00 (America/Los_Angeles) | HYBRID 50A-5132 (Sessler Conference Room), https://lbnl.zoom.us/j/91782268585, 50A-5132
ABSTRACT:
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.

Gilbert Holder (U. Illinois, Urbana-Champaign) "Particle Physics & Astrophysics with Wide Field mm-Wave Surveys"
2019-05-07 16:00 - 17:00 (America/Los_Angeles) | INPA Common Room (50-5026), 50-5026
Abstract:
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.”

Hitoshi Murayama (UCB/LBNL) "When a Symmetry Breaks"
2019-04-25 16:00 - 17:00 (America/Los_Angeles) | HYBRID 50A-5132 (Sessler Conference Room), https://lbnl.zoom.us/j/91782268585, 50A-5132
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:
https://physicstalks.lbl.gov/2019/misc/HitoshiMurayama.html

Aleksandra Dimitrievska and Karol Krizka "A Very Selective Summary of the Moriond QCD and EW Sessions"
2019-04-23 16:00 - 17:00 (America/Los_Angeles) | HYBRID 50A-5132 (Sessler Conference Room), https://lbnl.zoom.us/j/91782268585, 50A-5132
Abstract:
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.

Florian Beutler (U. Portsmouth) "Exploring Fundamental Physics with Galaxy Redshift Surveys"
2019-03-28 16:00 - 17:00 (America/Los_Angeles) | HYBRID 50A-5132 (Sessler Conference Room), https://lbnl.zoom.us/j/91782268585, 50A-5132
Abstract:
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.
