Lunchtime Seminars


 

Tuesdays  |  12:00 PM  |  Kolker Room, 26-414

 

Committee: Gunther Roland, Chair ~ Douglas Hasell

 


Jing Wang, MIT

Probing the Quark Gluon Plasma with Heavy Quarks with CMS Detector

Abstract: Heavy quarks are powerful tools for the study of the properties of the high-density QCD medium created in heavy-ion collisions as they are sensitive to the transport properties of the medium and may interact with the QCD matter differently from light quarks. As the main observables to study the medium effect, nuclear modification factors (RAA) of heavy-flavor particles provides insights into the flavor dependence of in-medium parton energy loss, and azimuthal anisotropy coefficient (vn) of heavy-flavor particles provides information about the degree of the thermalization of the bulk medium. On the other hand, the measurement of the production of strange heavy-flavor mesons can study harmonization mechanism in heavy-ion collisions. Furthermore, the production of heavy-flavor particles in jets is sensitive to the gluon splitting and the role of medium response.

Over the past few years, using the large statistics proton-proton and PbPb samples collected at 5.02 TeV during the 2015 LHC run, high precision measurements of heavy-flavor mesons have been performed with the CMS detector. In this talk, the results of open heavy flavor particle RAA and vn are presented. In particular I will discuss the most recent measurement of Bs meson RAA which is the first measurement of strange beauty hadrons in heavy-ion collisions, and the first D meson production in jets study performed by CMS experiment.

time:    Noon
place:   Kolker Room (26-414)

(Lunch will be served at 11:50)


 


Danielle Norcini, Yale University

PROSPECTing for reactor neutrinos at short baselines

Abstract: Since the discovery of the antineutrino, reactor experiments have played a key role in determining the properties of neutrinos. Results from recent theta13 experiments suggest a disagreement between the observed antineutrino flux and energy spectrum when compared to detailed predictions. Sterile neutrinos and corrections to complex nuclear models have been posed to explain the discrepancy. PROSPECT, the Precision Reactor Oscillation and Spectrum Experiment, studies reactor antineutrinos at baselines less than 10m from the High Flux Isotope Reactor at ORNL to search for eV-scale sterile neutrinos and make the world’s most precise measurement of the U-235 antineutrino spectrum. After 2 years of construction PROSPECT started data taking in Spring 2018. This talk describes the design and assembly of the detector, background characterization at the Earth’s surface, and the first PROSPECT physics.

time:    Noon
place:   Kolker Room (26-414)

(Lunch will be served at 11:50)


 

 


Afroditi Papadopoulou, MIT

Electrons-4-Neutrinos: Leveraging Electron Scattering for Precision Neutrino Oscillation Studies

Abstract: Neutrino physics is entering an age of precision measurements. A number of experiments have firmly established the existence of neutrino oscillations and determined the corresponding squared mass differences and mixing angles. These measurements have provided unambiguous evidence that neutrinos have non-vanishing masses.

The large θ13 mixing angle will enable future experiments to search for leptonic CP violation in appearance mode, thus addressing one of the outstanding fundamental problems of particle physics. These searches will involve high precision determinations of the oscillation parameters, which in turn require a deep understanding of neutrino interactions with the atomic nuclei comprising the detectors.

In view of the achieved and planned experimental accuracies, the treatment of nuclear effects is indeed regarded as a leading source of systematic uncertainty. In this context, a key role is played by the availability of a wealth of electron scattering data. I will present new data from the Jefferson Lab CLAS detector and how its used to test the accuracy of current neutrino energy reconstruction algorithm, the implication of their inefficiencies to future high-precision oscillation studies and their ability to improve theoretical models used in neutrino-nucleus interactions event generator.

time:    Noon
place:   Kolker Room (26-414)

(Lunch will be served at 11:50)


 



Joseph Patrick Johnston, MIT

Prospects for Exploring New Physics with CEvNS

Abstract: Coherent Elastic Neutrino Nucleus Scattering (CEvNS) is a standard model process that, although predicted for over 40 years, was only recently discovered at the Spallation Neutron Source. Detection at a nuclear reactor will both enable applications of neutrinos for remote nuclear monitoring, and provide a powerful probe of new physics by measuring a lower energy portion of the CEvNS spectrum.

Several current experiments aim to use cryogenic bolometers to detect CEvNS at a nuclear reactor. I will discuss several such projects with a focus on Ricochet, a project that will use Ge and Zn bolometers to measure CEvNS. I will then present recent work on the potential to probe new physics, including a neutrino magnetic moment and constraints on NSI parameters that are important for upcoming experiments such as DUNE.

time:    Noon
place:   Kolker Room (26-414)

(Lunch will be served at 11:50 a.m.)


 



NO TALK--COLUMBUS DAY HOLIDAY


 



Valérian Sibille, MIT

The Karlsruhe Tritium Neutrino Experiment: First Tritium Runs

Abstract: The discovery of neutrino oscillations has proven that neutrinos have mass, and yet, for all the efforts to constrain the neutrino masses via direct and indirect methods, the neutrino mass scale remains undetermined.

The KATRIN experiment aims at measuring the effective electron antineutrino mass with a 0.2 eV (90%C.L.) sensitivity by analysing the β-decay spectrum of molecular tritium near its endpoint. This 70 m-long experiment consists of a windowless gaseous source, differential and cryogenic pumps for tritium retention, and a main spectrometer acting as a high-pass filter for the electrons collimated towards the 148-pixel silicon detector.

This talk will focus on the commissioning of the KATRIN experiment, with an emphasis on its first tritium runs. The description of the β-decay spectrum near the endpoint, the response function of the apparatus, and the statistical tools used for the interpretation of the observed integrated spectrum will be highlighted.

time:    Noon
place:   Kolker Room (26-414)

(Lunch will be served at 11:50 a.m.)


 



Gabriel Collin, MIT

Simulating Light in Large Volume Detectors Using Metropolis Light Transport

Abstract: In gigaton scale neutrino detectors, such as the IceCube experiment, interaction products are detected by the Cherenkov radiation emitted by their passage through the detector medium. Simulating this propagation of light is traditionally approached through ray tracing. This is complicated by the sparsity of the detector: the vast majority of light rays are scattered and absorbed by the detector medium, with only a tiny fraction finding their way to a light sensitive element. In this presentation, I develop an alternative method, based on the Metropolis light transport algorithm used in the CGI industry. This method poses the problem as a classical path integral, and samples only the paths of light rays that end on a light sensitive element using a Markov chain Monte-Carlo. This yields a significant performance increase compared to ray tracing when simulating the timing distribution of light detected by a photo-sensitive element.

time:    Noon
place:   Kolker Room (26-414)

(Lunch will be served at 11:50 a.m.)


 



Naohito Saito, J-PARC/KEK

A Novel Precision Measurement of Muon g-2/EDM at J-PARC

Abstract: A precision measurement of muon dipole moments have been playing important role to test the standard model of particle physics in the past and to shape the new physics in recent years. We plan to launch an experiment to perform precision measurements of the muon anomalous magnetic moment (aka "g-2") and electric dipole moment with a novel technique at Japan Proton Accelerator Research Complex, J-PARC. This experiment requires a muon source with very small emittance, muon acceleration, spiral injection of the muon beam into super-precision magnetic field with 66-cm diameter and high-rate tracking system. The current status and prospect of the experiment will be described in this seminar.

time:    Noon
place:   Kolker Room (26-414)

(Lunch will be served at 11:50 a.m.)

 



Aram Apyan, MIT

Precision Tests of the Electroweak Sector of the Standard Model

Abstract: The electroweak sector of the Standard Model (SM) of particles can be tested either with precision measurements of fundamental observables or with direct tests of its underlying non-Abelian gauge structure. Precise measurements of the weak mixing angle and the mass of the W boson probe the consistency of the SM. Measurements of vector boson scattering processes probe the gauge structure of the electroweak sector. Recent measurements of the electroweak gauge boson production cross sections and first VBS measurements in proton-proton collisions at 13 TeV at the Large Hadron Collider (LHC) are discussed. At the LHC, VBS is characterized by presence of two gauge bosons in association with two forward jets with large rapidity separation and a large djiet mass. Searches of anomalous quartic gauge couplings are also reported.

time:    Noon
place:   Kolker Room (26-414)

(Lunch will be served at 11:50 a.m.)


 



Xinmei Niu, MIT

Precision measurements of the Z boson and Higgs boson searches in di-muon channel with CMS detector

Abstract: In this presentation, inclusive and differential Z boson cross section measurements in di-muon channel with pp collisions at 13 TeV are discussed. Measurements of the transverse momentum distribution of Z boson can be used to probe resummation techniques in addition to higher-order correction in QCD calculations. A complementary approach to monitor luminosity at LHC using Z boson events is described. Searches for Standard Model and Beyond Standard Model Higgs in di-muon channel on top of the Drell-Yan backgrounds are also reported.

time:    Noon
place:   Kolker Room (26-414)

(Lunch will be served at 11:50 a.m.)


 



NO TALK--THANKSGIVING HOLDIAY WEEK


 



Alejandro Diaz, MIT

Updated Results For the MiniBooNE Short-Baseline Neutrino Oscillation Experiment

Abstract: In its original 2002-2007 run, the MiniBooNE neutrino experiment observed an anomalous and yet-unexplained excess of electron-like events at low energy neutrino energies. This observation is one of several that has pushed the discussion of, and search for, sterile neutrinos. Since 2016, MiniBooNE has been collecting new neutrino-mode data, doubling the statistics from the original 2002-2007 run. The updated results continue to observe an excess consistent with oscillations. Furthermore, this excess is consistent with that observed by MiniBooNE’s precursor experiment, LSND. In this talk, the new MiniBooNE results will be discussed, and we will explore present and future endeavors to resolve the origin of these anomalous results.

time:    Noon
place:   Kolker Room (26-414)

(Lunch will be served at 11:50 a.m.


 



Saptarshi Chaudhuri, Stanford University

Quest for the QCD Axion: DM Radio and Fundamental Limits of Electromagnetic Detection

Abstract: We discuss searches for the QCD axion, a well-motivated cold-dark matter candidate that also solves the strong CP problem in quantum chromodynamics. We focus on axion dark matter searches probing the coupling to electromagnetism and establish fundamental limits on detection subject to the Standard Quantum Limit on phase-insensitive amplification. These limits demonstrate that single-pole resonators are near-optimal single-moded detectors for axion dark matter. Furthermore, we show that proper optimization of measurement backaction and sensitivity outside of the resonator bandwidth can increase scan rates by up to five orders of magnitude at low frequency. We present DM Radio, a tunable, lumped-LC resonant search for axion and hidden-photon dark matter between 100 Hz and 300 MHz. Its design is informed by the fundamental limits and optimization statements. The prototype experiment, the DM Radio Pathfinder, uses a 4K liquid-helium-cooled detector to search for hidden photons in the 100 kHz-10 MHz frequency range. It is presently conducting engineering runs and narrowband measurements and will begin science scans in 2019. We discuss progress on the Pathfinder experiment, including investigations of resonator loss mechanisms and capacitive tuning, characterization of SQUID noise, and development of calibration and data analysis protocols. We present future plans and upgrades. In particular, we discuss a search using a detector volume of one cubic meter cooled to 10 mK and a several-Tesla magnet which will have sensitivity to the QCD axion above a few MHz.

time:    Noon
place:   Kolker Room (26-414)

(Lunch will be served at 11:50 a.m.)


 



Dylan Rankin, MIT

Future LHC Triggering: Using Field-Programmable Gate Arrays to Solve Complex Modern Problems

Abstract: FPGAs have been used for decades in both physics and industry for their speed and low power consumption. However, their use has been primarily limited to relatively simple tasks, especially when compared with those tasks assigned to CPUs. Modern advancements in FPGA programming with HLS and derived software like hls4ml are now changing this paradigm by allowing increasingly more sophisticated algorithms to be implemented in firmware.

This talk will use examples from the CMS trigger upgrade in the form of the Particle Flow algorithm and machine learning to showcase new possibilities for the use of FPGAs, both in homogeneous and heterogeneous computing environments. These algorithms greatly expand the trigger capabilities, and allow us to rethink the scope of possible physics measurements at CMS.

time:    Noon
place:   Kolker Room (26-414)

(Lunch will be served at 11:50 a.m.)