LBNL Physics Division Research Progress Meetings

Reserved
2017-01-26 16:00 - 17:00, 2017-01-31 16:00 - 17:00, 2017-02-02 16:00 - 17:00, 2017-02-07 16:00 - 17:00 (America/Los_Angeles) | Zoom Talk, 50A-5132, Berkeley, ca, 94720

Peter Sorensen (LBNL) "How to See Dark Photons: A Status Report on a New Avenue in Direct Detection"
2017-02-09 16:00 - 17:00 | Zoom Talk, 50A-5132, Berkeley, ca, 94720
Abstract:
I will discuss the new (old) idea that dark matter may reside in a hidden sector whose interactions with the standard model are mediated by a dark photon. Possibilities for direct detection of such particles will be discussed. This is particularly timely given the recent DOE call for a small scale direct detection experiment that can search new parameter space.
20170209_RPM slides

Manuel Franco Sevilla (UCSB) "Strategies for Searches of Physics Beyond the Standard Model in the XXI Century"
2017-02-14 16:00 - 17:00 | Zoom Talk, 50A-5132, Berkeley, ca, 94720
ABSTRACT:

At the end of the XIX century, Lord Kelvin summarized a widespread feeling among physicists by saying that “physics is essentially complete, save for two little clouds”. The “clouds” he was referring to were the puzzling results from two measurements, the Michelson-Morley experiment and the Black-body spectrum, whose explanations ushered in an unprecedented era of discoveries that stretched throughout most of the XX century. After the culmination of the Standard Model in the 70’s, the field of particle physics has found itself in a similar situation. Today, the “clouds” guiding the searches for physics beyond the Standard Model are issues like dark matter or the hierarchy problem. Using SUSY searches at CMS and the measurement of B->D(*)TauNu decays at BaBar as models, I will give an overview of some of the main strategies that are being followed in the quest to find new physics in the XXI century.

Aritoki Suzuki (UCB) "Next Generation Cosmic Microwave Background Polarimetry Experiment - Enabling Technologies for an Order of Magnitude Increase in Detector Count"
2017-02-16 16:00 - 17:00 | Zoom Talk, 50A-5132, Berkeley, ca, 94720
Precision measurements of Cosmic Microwave Background (CMB) temperature anisotropies over the last two decades have been a spectacular success, constraining all six parameters of the LambdaCDM cosmological model to the percent level. However, while CMB temperature is well explored, current experiments are just now becoming sensitive enough to explore the rich physics of CMB polarization.
“Stage-II” CMB experiments started to deploy in early 2010’s, contain ~1,000 millimeter-wave, polarization-sensitive detectors, and have discovered B-mode polarization due to weak gravitational lensing and set limits on B-modes due to inflationary gravitational waves. “Stage-III” experiments have begun to deploy this year and contain ~10,000 detectors for an order-of-magnitude improvement in sensitivity.
Looking to the future, the CMB community has begun studying “CMB-S4”, a “Stage-IV” experiment that will contain ~500,000 detectors, a factor ~100 increase over experiments currently in the field. The goal of CMB-S4 is to make a definitive measurement of CMB polarization from the ground in order to explore inflationary scenarios, constrain the sum of the neutrino masses, and search for new physics within the early universe.
During this presentation, I will discuss the exciting science objectives of modern CMB experiments, the tremendous technological challenge of fielding large numbers of highly-sensitive detector arrays, and the advancement in technologies we are developing to overcome these challenges to conduct the ultimate CMB polarization measurement.

Stefano Camarda (CERN) "Electroweak precision physics at the LHC"
2017-02-21 16:00 - 17:00
Abstract:
Precision measurements of electroweak observables offer a viable
option for finding indications of new physics and also guidance for
the next big discovery. In this talk, I will focus on the latest
electroweak precision measurements at the LHC, with an emphasis on the
W-boson mass measurement recently published by ATLAS. The evaluation
of the experimental systematic uncertainties, as well as the
uncertainties due to the modeling of the vector boson production and
decay of the ATLAS W-boson mass measurement will be discussed.
In addition, the LHC results will be put in context to previous
measurements at the Tevatron and LEP colliders.

Alvaro Chavarria (U. Chicago) “Solid-State Imaging Detectors for Low-Energy Particle Physics”
2017-02-23 16:00 - 17:00 | Zoom Talk, 50A-5132, Berkeley, ca, 94720
Abstract:
The low noise, high spatial resolution and reliable performance of charge-coupled devices (CCDs) and complementary metal-oxide-semiconductor (CMOS) active-pixel sensors have made them detectors of choice for digital imaging. Although the slow time response of these devices has limited their application in high-energy particle physics, for the case of rare-event searches, where the particle interaction rate is extremely low, their properties can be fully exploited to build detectors that outperform in many aspects the traditional technologies of the field. I will present recent results from the DAMIC experiment, a low-mass dark matter search consisting of low-noise CCDs deployed in the SNOLAB laboratory. I will show how the exquisite spatial resolution of the detector allows for particle identification, and provides the unique capability to reject sequences of radioactive decay with utmost efficiency. These techniques can be extended to the search for neutrinoless double beta decay. I will present a recent proposal where we argue that a large array of amorphous Se-82 imagers based on CMOS technology could achieve the background levels necessary to test if neutrinos are Majorana fermions even in the case of a normal hierarchy of neutrino masses.

Yun-Tse Tsai (SLAC/Stanford) "Exploring ν Territory: Using LArTPC Technology ("ν“ here is a Greek alphabet accounting for neutrinos)"
2017-02-28 16:00 - 17:00 | Zoom Talk, 50A-5132, Berkeley, ca, 94720
Abstract:

The discovery of neutrino oscillation, which implies neutrinos have non-zero masses, is the first instance of a conflict with the Standard Model of particle physics. The fruitful results from neutrino experiments in the past two decades have opened a window into a new territory, where the unanswered questions in the current theory, such as the observed matter-antimatter asymmetry, may be addressed by the upcoming precision measurements.
In this talk, I will introduce the core topics of neutrino physics and the requirements of neutrino experiments, focusing on the technology of liquid argon time projection chamber (LArTPC). The outstanding spatial and energy resolution of LArTPC provides us with a promising apparatus for the required precision. In particular, I will discuss detection of neutrinos from supernova explosions, and searches for other weakly interacting particles as well as rare physics processes. I will talk about the MicroBooNE experiment, the first large LArTPC in the U.S., its recent results, and the future LArTPC experiments.

Javier Tiffenberg (Fermilab) "Things to do with less than one electron: the dawn of the ultimate ionization detector"
2017-03-02 16:00 - 17:00 | Zoom Talk, 50A-5132, Berkeley, ca, 94720
Abstract:

Silicon charged coupled devices (CCDs) have proven to be exceptional for the detection and measurement of photons and other ionizing radiation. Their low energy threshold of 50eV (~14 e-) have made them ideal for astronomical aplications and for detectors exploring Neutrino interactions (CONNIE) and searching for Dark Matter particles (DAMIC). However, the counting of individual photons and energy depositions below 50 eV has proven difficult due to an inability to reduce electronic noise below the level of a single charge carrier. Here I’ll present the results of a collaboration between Fermilab and LBL to build a Sub-Electron Noise Skipper Experimental Instrument (SENSEI) which uses a non-destructive readout technique to achieve stable readout for a thick fully depleted silicon CCD in the far sub-electron regime (∼ 0.05 e − rms/pix). This is the first time that discrete sub-electron counting has been achieved reproducibly over millions of pixels on a stable, large-area detector (7 cm^2 ) with large dynamic range. This innovative technology has nearly immediate implications for a wide range of scientific disciplines including astronomy and fundamental particle physics.

slides: pdf

Elisabetta Pianori (CERN) "Unveiliing the Origin of Particles' Mass: Higgs Boson Coupling Measurements at the LHC"
2017-03-07 16:00 - 17:00 | Zoom Talk, 50A-5132, Berkeley, ca, 94720
Abstract:
Although the Standard Model (SM) of particle physics is a very successful theory, it fails to explain the origin of particles’ mass. If the Higgs mechanism, developed in the 60s as a solution to this puzzle, is the correct theory of Nature, a new fundamental particle, the Higgs boson, must exist. In 2012, at the LHC, a particle consistent with the Higgs boson was discovered. The theory prescribes the strength of the Higgs boson interaction with SM particles, but physics beyond the Standard Model could modify it. In this talk I will present the evidence of direct couplings of the Higgs boson to fermions and compare them with the predictions. I will also discuss the ATLAS+CMS combined measurement of the Higgs boson production and decay rates, and how they constrains the Higgs boson’s couplings to SM particles and the existence of new physics.

Timon Heim (LBNL) “Challenges of the ATLAS Phase 2 Tracker Upgrade”
2017-03-09 16:00 - 17:00 | Zoom Talk, 50A-5132, Berkeley, ca, 94720
For the phase 2 upgrade of the ATLAS experiment at the LHC, its inner detector will be replaced by a new all-silicon tracker, the Inner Tracker (ITk). This upgrade is necessary both because the inner detector will have reached its intended lifetime and to maintain tracking performance of the ATLAS detector under the demands of a 5 to 7 times higher collision rate after the high luminosity upgrade of the LHC. This presentation will give an overview and status of the ITk Strip and Pixel detector. It will highlight one major challenge for each of the detectors: the on-module DC-DC powering circuit of the ITk Strip detector and the 65nm readout chip of the ITk Pixel detector. Furthermore I will present a readout concept which could be used as a base for a common ITk readout software core. This core can operate with multiple hardware platforms and user interfaces, an essential feature for the successful transition from prototyping and production to detector commissioning and operation.

Prof. Stacy McGaugh (Case Western) "The Radial Acceleration Relation in Rotationally Supported Galaxies"
2017-03-16 16:00 - 17:00 | Zoom Talk, 50A-5132, Berkeley, ca, 94720
ABSTRACT:
We report a correlation between the radial acceleration traced by rotation curves and that predicted by the observed distribution of baryons. The same relation is followed by 2693 points in 153 galaxies with very different morphologies, masses, sizes, and gas fractions. The correlation persists even when dark matter dominates. Consequently, the dark matter contribution is fully specified by that of the baryons. The observed scatter is small and largely dominated by observational uncertainties. This radial acceleration relation is tantamount to a natural law for rotating galaxies.

Roger O’Brient (JPL) “The Search for Inflationary Gravitational Waves: Current Status of the BICEP Program and Next Generation Instrumentation.”
2017-03-21 16:00 - 17:00 | Zoom Talk, 50A-5132, Berkeley, ca, 94720
Abstract:
For over a decade, the BICEP collaboration has been deploying small aperture telescopes to the South Pole Station to map B-mode polarization in the Cosmic Microwave Background and
search for evidence of primordial gravitational waves. If detected, they would allow physicists
to constrain physics at energy scales of ~10 16 GeV levels. To date, this program places the
tightest constrains on the tensor-scalar ratio of r<0.07 (95% confidence). We are at an
important point in our program as we transition into “Stage-3” instruments with the BICEP-
array, which will search to a level of r>0.01. This rapid progress is fueled by the antenna-
coupled superconducting bolometers that we have developed at NASA’s Jet Propulsion
Laboratory. In my talk, I’ll summarize the science case for these experiments, describe the
instruments themselves with a focus on the detectors, discuss the recently collected data, and
comment on the future of our program. In particular, Thermal KIDs, an emerging bolometer
technology, will be critical for this next phase. Finally, I’ll comment on how LBL and DOE can
and will play a future role in this exciting frontier of fundamental physics.

Megan Eckart (NASA) "X-ray Astrophysics Enabled by Microcalorimeters: from Recent Observations to Next-Generation Technologies"
2017-03-23 16:00 - 17:00 | Zoom Talk, 50A-5132, Berkeley, ca, 94720
Abstract:
High-resolution imaging spectroscopy in the soft x-ray waveband (0.1-10 keV) is an essential tool for probing the physics of the x-ray universe. Unique line diagnostics available in this waveband allow transformative scientific observations of a wide array of sources. For example, measurements of turbulence in the intra-cluster medium of galaxy clusters can be used to calibrate hydrodynamic simulations used in cosmology; and measurements of outflow processes from supermassive black holes may identify the key mechanism that regulates the co-evolution of host galaxies and their central black holes. I will introduce the microcalorimeter, a low-temperature detector capable of x-ray photon counting with high spectral resolution, and discuss observations of the Perseus Cluster made using our microcalorimeter instrument that launched aboard the Japanese-led Hitomi (Astro-H) mission in 2016. I will discuss our recent advances using transition-edge-sensor (TES) microcalorimeters and identify areas in detector, readout, and instrument development that are needed for next-generation instrumentation for space- and laboratory-based experiments. Techniques and challenges will be compared to those of envisaged cryogenic CMB and direct dark matter detection experiments.

Haichen Wang (LBNL) Title: Search for physics beyond the Standard Model using multijet events with the ATLAS detector at the LHC
2017-03-28 16:00 - 17:00 | HYBRID 50A-5132 (Sessler Conference Room), https://lbnl.zoom.us/j/91782268585, 50A-5132
Abstract:
Search for physics beyond the Standard Model (SM) has been one of the most important goals of the physics program at CERN’s Large Hadron Collider (LHC). Among all the final states, the multijet final state has long been considered as a challenging one for the search of physics beyond the SM due to its large background. Though, exciting new physics phenomena, such as the production of black hole as well as massive supersymmetric (SUSY) particles, may well result in signals in the multijet final state. I present searches for physics beyond the SM using multijet events from 13 TeV collision data taken in 2015 and the first half of 2016 by the ATLAS experiment at the LHC. I focus on a search for the production of black hole and a search for massive supersymmetric particles decaying to many jets via R-Parity Violating (RPV) couplings. The two examples represent searches targeting physics beyond the SM at different mass scales, and therefore different analysis strategies are employed. These searches have greatly improved the sensitivity of the LHC to the black hole production and RPV SUSY scenarios, and they are complementary to searches using events of leptons, photons and missing transverse energy.

Professor Sunil Golwala (Caltech) "The SuperCDMS SNOLAB Search for Low-Mass Dark Matter"
2017-03-30 16:00 - 17:00 | Zoom Talk, 50A-5132, Berkeley, ca, 94720
Abstract
The dark matter problem, known since the 1930s, has only grown in importance during the current era of precision cosmology. We remain unable to answer the question: what is the matter that makes of 5/6 of the universe’s matter density? Yet we are also in an era of unparalleled theoretical creativity and experimental opportunity. Theorists have vastly expanded the parameter space for weakly interacting massive particle dark matter in the last decade. New experimental constraints and candidates have emerged from the LHC, other accelerator experiments, and direct and indirect detection dark matter searches. I will summarize the current state of experimental searches for particle dark matter and focus on the upcoming search at low mass with the SuperCDMS SNOLAB experiment.

Director's Physics Division Review
2017-04-12 08:00 - 2017-04-13 17:00

Heather Gray (LBNL) Title: The Art of the Impossible: Probing challenging Higgs channels at the LHC
2017-04-27 16:00 - 17:00
Abstract:

In the technical design report of the LHC experiments, measurements of the Higgs coupling to top and bottom quarks and the width of the Higgs were either predicted to be extremely challenging, if not impossible at the LHC. Yet, ATLAS and CMS have both produced interesting results for all these channels. I will highlight selected aspects of these measurements to discuss what allowed ATLAS and CMS to probe the “impossible“.

Manoj Kaplighat (UC, Irvine) "The self-interacting dark matter paradigm: motivations and tests"
2017-05-04 16:00 - 17:00 | HYBRID 50A-5132 (Sessler Conference Room), https://lbnl.zoom.us/j/91782268585, 50A-5132
Abstract:

I will describe how a simple model where dark matter has large elastic self-interactions (cross section over mass of order barns per GeV) can fully explain the observed diversity of all galactic rotation curves. I will summarize the constraints imposed on model building by observations of clusters of galaxies and end with an outline of tests of this paradigm.

Prof. Rouven Essig (TBA) " Direct Detection of sub-GeV Dark Matter"
2017-05-11 16:00 - 17:00 | Zoom Talk, 50A-5132, Berkeley, ca, 94720
Abstract:
Dark matter makes up 85% of the matter in our Universe, but we have yet to learn its identity. A broad array of search strategies are needed to probe for non-gravitational interactions between dark matter and ordinary matter. While most searches focus on Weakly Interacting Massive Particles (WIMPs) with masses between 1 GeV and 1 TeV, it is imperative to also consider other motivated dark matter candidates. In this talk, I will discuss dark matter with MeV-to-GeV masses, which is a theoretically and phenomenologically appealing possibility and presents a new frontier in the search for dark matter. I will highlight novel dark matter direct-detection strategies that can probe this under-explored mass range. I will review how XENON10 data already probes dark matter with masses as low as a few MeV, and present recent constraints using XENON100 data. I will then discuss improvements expected from near-future experiments, focusing on xenon, semiconductor, and scintillator targets. This includes, for example, SENSEI, which is a new ultra-low-threshold silicon CCD detector that is poised to probe vast new regions of parameter space in the next few years. I will also present a few simple benchmark models of MeV-to-GeV dark matter, and contrast direct-detection probes with searches at colliders and fixed-target experiments.

Physical Sciences Institution Review
2017-05-23 08:00 - 2017-05-25 17:00

Florian Beutler (Portsmouth) "On the reliability of Baryon Acoustic Oscillation (BAO) measurements"
2017-06-01 08:00 - 17:00 | HYBRID 50A-5132 (Sessler Conference Room), https://lbnl.zoom.us/j/91782268585, 50A-5132
Abstract:

In this talk I will discuss the reliability of the Baryon Acoustic Oscillation (BAO) signal in the distribution of galaxies. The solid theoretical understanding of this observable means that it represents one of only a few cosmological observables that are not yet dominated by systematic errors. This is one reason why BAO are one of the main science drivers for future galaxy surveys like DESI and Euclid.

I will discuss my recent work on the relative velocity effect as one potential systematic for BAO. The relative velocity effect originates from the same physical effects which imprinted the BAO signal and therefore acts on the same scale. I will introduce this effect in detail, discuss how we can include it in our modeling and present current constraints from the Baryon Oscillation Spectroscopic Survey (BOSS).

Marcel Vos (CERN) "Prospects for Top Physics at the LHC and Beyond"
2017-06-22 16:00 - 17:00 | HYBRID 50A-5132 (Sessler Conference Room), https://lbnl.zoom.us/j/91782268585, 50A-5132
ABSTRACT:
Experiments at the Large Hadron Collider are characterizing the top quark and its interactions to unexpected precision. The combination of direct searches for new particles and indirect constraints from precision measurements provides powerful limits on extensions of the Standard Model. I start the seminar with a brief overview of top physics today and of the prospects for precision top physics of future LHC runs. This sets a high bar for future colliders that are to continue the programme initiated by Tevatron and LHC. In the second half of the seminar I discuss the potential of the future facilities envisaged in Asia and Europe. Powerful electron-positron machines have exquisite potential for key measurements such as the top quark mass and electro-weak couplings. Hadron colliders with a center-of-mass energy that significantly exceeds that of the LHC can probe the QCD interactions of the top quark an order of magnitude deeper and can provide a precise measurement of the top Yukawa coupling.

Zachary Marshall (LBNL) "Title: Searching for SUSY in Big Data at the LHC"
2017-07-13 08:00 - 16:00 | HYBRID 50A-5132 (Sessler Conference Room), https://lbnl.zoom.us/j/91782268585, 50A-5132
ABSTRACT:
One of the most enticing and popular additions to the Standard Model of particle physics, Supersymmetry, is the target of a wide range of searches at the Large Hadron Collider at CERN. The ATLAS and CMS experiments have produced an incredible variety of searches, but Supersymmetry remains elusive. We will discuss the results of some of the recent searches that demonstrate the dexterity of both experiments, and point out which assumptions might be playing an important role in the interpretation of those results. There are still many ways Supersymmetry could have escaped detection up to now, and we will also point towards some of the next directions for searches for Supersymmetry at the LHC. Along the way, we will discuss some of the software and computing challenges that come with world-wide analysis of tens of billions of events, and how the

Tova Holmes (ATLAS) "The FTK: Global Tracking for the ATLAS Trigger"
2017-08-15 16:00 - 17:00 | HYBRID 50A-5132 (Sessler Conference Room), https://lbnl.zoom.us/j/91782268585, 50A-5132
Abstract:
The ATLAS Detector is in the process of upgrading its Trigger and Data Acquisition system to include global processing of tracks using the FastTracKer (FTK). The FTK uses a parallelized structure to identify and reconstruct the properties of tracks from the 98 million channels of the the ATLAS silicon detectors. With the use of hardware-level pattern matching and a two-tiered track-fitting system, this reconstruction can be performed on all events passing the first-stage ATLAS trigger, with a rate up to 100 kHz and requiring less than 100 µs per event. These capability opens new doors for b-jet and tau triggering, allows for the suppression of pile-up effects on missing energy triggers, and can even be used to isolate BSM signatures involving long-lived particles. This talk will discuss the physics case for the FTK, an overview of its design, and its integration status.

Larry Lee (Harvard) "Searches for Sneaky SUSY at the ATLAS Experiment"
2017-08-17 16:00 - 17:00 | HYBRID 50A-5132 (Sessler Conference Room), https://lbnl.zoom.us/j/91782268585, 50A-5132
ABSTRACT:
Despite the lack of a sparticle discovery at the Large Hadron Collider, and despite the fact that most of the discovery potential has shriveled to an upsetting size, supersymmetry (SUSY) remains the most motivated solution to the Standard Model’s inadequacies. Because of this (and a large dose of stubbornness), we are forced to consider ways the nominal search strategy may have missed a discovery. Must SUSY present itself with lots of high-momentum objects and large missing transverse energy just because it’d be easy to find? This talk will discuss recent SUSY searches at ATLAS targeting signatures without large missing transverse energy as well as those sensitive to long-lived sparticles.

Ben Nachman (LBNL) and Mateus Ploskon (LBNL) "Jet Substructure"
2017-08-31 16:00 - 17:00 | HYBRID 50A-5132 (Sessler Conference Room), https://lbnl.zoom.us/j/91782268585, 50A-5132
ABSTRACT:
The LBNL xTalk (“cross-talk”) series provides a forum for the exchange of ideas between groups and across lab divisions. Each seminar is focused on a theme which is confronted from two perspectives. In particular, the talks are given by two presenters from different domains. The format is informal (chalk talk!) and is designed to be entertaining and engaging. Come prepared to learn and ask about details with the experts in order to stimulate collaborations between groups. We hope that this will strengthen the program at the lab and spread new ideas.
For the first xTalk, we will have Mateusz Ploskon from Nuclear Science and Benjamin Nachman from the Physics Division to discuss how jet substructure is used in ALICE/STAR and in ATLAS. Jets are collimated sprays of particles resulting from quarks and gluons produced at high energy. The radiation pattern within jets encodes a wealth of information about the parton that initiated it. Jet substructure is a hot topic in pp for tagging boosted W/Z/H bosons and also recently for precision probes of Quantum Chromodynamics (QCD); in heavy ion collisions, jet substructure is an exciting new probe of medium modifications. Please join us for this comparative discussion of how jet substructure is used in two very different environments!

Cora Dvorkin (Harvard) "Discovering New Physics Beyond the Standard Model with Cosmological Data Sets"
2017-09-14 16:00 - 17:00 | 70A-3377, 70A-3377
Abstract:
Cosmological observations have provided us with answers to age-old questions, involving the age, geometry, and composition of the universe. However, there are profound questions that still remain unanswered. I will describe ongoing efforts to shed light on some of these questions.
In the first part of this talk, I will explain how we can use measurements of the CMB and the large-scale structure of the universe to reconstruct the detailed physics of much earlier epochs, when the universe was only a tiny fraction of a second old. In particular, I will show how we can probe the shape of the inflationary potential, extra degrees of freedom during inflation, and the signature of possible particles with mass and spin during this period.
In the last part of the talk, I will discuss how we can use observations at large scales and sub-galactic scales (through strong gravitational lensing) to improve our understanding of another open question in fundamental physics: the particle nature of dark matter.
