## Lunchtime Seminars

#### Via Zoom:   https://mit.zoom.us/j/95129215697

Vitali Choutko, MIT

Latest Results from the Alpha Magnetic Spectrometer on the International Space Station

Abstract:
The Alpha Magnetic Spectrometer (AMS) is a precision particle physics detector on the International Space Station (ISS) conducting a unique, long-duration mission of fundamental physics research in space.

The physics objectives include the precise studies of the origin of dark matter, antimatter, and cosmic rays as well as the exploration of new phenomena. AMS was installed on the ISS on May 19, 2011. The presented results based on 150 billion charged cosmic ray events up to multi-TeV energies. This includes the fluxes of positrons, electrons, antiprotons, protons, and nuclei. These results provide unexpected information, which cannot be explained by the current theoretical models. The accuracy and characteristics of the data, simultaneously from many different types of cosmic rays, provide unique input to the understanding of origins, acceleration, and propagation of cosmic rays.

#### Via Zoom:   https://mit.zoom.us/j/95129215697

Brooke Russell, LBL

Readying for the Neutrino Onslaught: Design and Prototyping for the DUNE LAr Near Detector

Abstract:
The Deep Underground Neutrino Experiment (DUNE) is a next generation long-baseline neutrino oscillation experiment designed to resolve the neutrino mass hierarchy to 5σ precision in the near-term and after a 10 year exposure observe charge-parity violation in the neutrino sector to a precision of 5σ for 50% of all δCP values. A performant near detector is critical for reducing systematic uncertainties in order to realize DUNE neutrino oscillation physics sensitivities. With optical segmentation and high photodetector coverage, the liquid argon time projection chamber component (ND-LAr) of the DUNE Near Detector complex is designed to be resilient to the 55 neutrino interactions per beam spill expected from the intense LBNF neutrino beam. In addition, the expected beam neutrino pile-up at ND-LAr necessitates pixelated charge readout that eliminates the ambiguities common to projective wire or strip charge readout. Furthermore, unambiguous 3D charge information facilitates accurate time-tagging and thereby association to the correct neutrino interaction. LArPix incorporates low-power 64-channel custom ASICs with a mixed-signal large-format printed circuit board for an unambiguous 3D charge-readout. Here I focus on the design and prototyping program for ND-LAr with emphasis on LArPix performance evaluation.

#### Via Zoom:   https://mit.zoom.us/j/95129215697

Kelly Backes, Yale

Enhancing Axion Detection with Quantum Squeezing

Abstract:
The Haloscope at Yale Sensitive to Axion Cold dark matter (HAYSTAC) is the first dark matter detector to use quantum squeezed states to enhance the search for axions. The squeezed state receiver consists of two Josephson parametric amplifiers operating in a phase-sensitive mode. In this mode, the noise is squeezed, while the axion-sensitive signal is amplified. The use of this technology brings together the fields of quantum metrology and axion dark matter in an unprecedented way. We have now taken data with noise levels below the standard quantum limit, increasing the rate at which we can scan axion parameter space by two-fold. In this talk, I will give an overview of the operations of the HAYSTAC experiment, focusing on the operation of the squeezed state receiver and the new Bayesian-based analysis framework used to exclude axions in the 4.11 - 4.18 GHz range.

#### Via Zoom:   https://mit.zoom.us/j/95129215697

Ken Ng, MIT

Looking for Ultralight Bosons Using Black Hole Spins Measured from Gravitational Waves

Abstract:
Clouds of ultralight bosons - such as axions - can form around a rapidly spinning black hole, if the black hole radius is comparable to the bosons' wavelength. The cloud rapidly extracts angular momentum from the black hole, and reduces it to a characteristic value that depends on the boson's mass as well as on the black hole mass and spin. Therefore, a measurement of a black hole mass and spin can be used to reveal or exclude the existence of such bosons. Using hierarchical Bayesian inference, we can simultaneously measure the black hole spin distribution at formation and the mass of the scalar boson. Based on the black holes released by LIGO and Virgo in their GWTC-2, the data strongly disfavors the existence of scalar bosons in the mass range between          $1.3\times10^{-13}\,\mathrm{eV}$ and $2.7\times10^{-13}\,\mathrm{eV}$. Our mass constraint is valid for bosons with negligible self-interaction, that is with a decay constant $10^{14}~\mathrm{GeV}$. The statistical evidence is mostly driven by the two {binary black holes} systems GW190412 and GW190517, which host rapidly spinning black holes. The region where bosons are excluded narrows down if these two systems merged shortly ($\sim 10^5$ years) after the black holes formed. If time permits, we will also discuss the prospect of this search in the coming decade, as well as a multiband technique for precise measurement of boson mass.

#### Via Zoom:   https://mit.zoom.us/j/95129215697

Mark Broering, MIT

Developing a Highly Polarized 3He Atomic Beam Source for the nEDM@SNS Experiment

Abstract:
The neutron electric dipole moment (nEDM) continues to provide a proving ground in searches for Physics Beyond the Standard Model; as the limit on this value improves, plausible theories are further constrained. Beyond that, it also provides insight into Baryogenesis, the process by which the Big Bang produced more matter than antimatter. The first nEDM experiment was conducted 70 years ago, and new experiments have been improving the sensitivity ever since.

The neutron electric dipole moment search at Oak Ridge National Laboratory’s Spallation Neutron Source (nEDM@SNS) experiment will implement a new nEDM detection method, using 3He as a spin-state analyzer and co-magnetometer. The 3He capture cross-section for neutrons is minimized when the spins are parallel and maximized when they are anti-parallel, making 3He a viable Ultra Cold Neutron spin state detector. This new method will allow the nEDM@SNS experiment to detect a nEDM as small as two orders of magnitude below the current limit set by previous experiments. Development of an appropriate highly-polarized (95%) 3He source is critical to this experiment. Magneto-optic techniques are unlikely to reliably provided the required polarization, leaving an Atomic Beam Source (ABS) as the most desirable option. This device uses a quadrupole magnet system to preferentially select a spin state in 3He that has been cooled to 1.5 K or below. A brief overview of the nEDM@SNS experiment, focusing on the detection method, will be provided as well as recent results from the ABS development occurring at MIT.

#### Via Zoom:   https://mit.zoom.us/j/95129215697

Daniel Takaki, University of Kansas, CERN

Entanglement and Quantum Tomography for Collider Physics

Abstract:
Quantum mechanics is experiencing an experimental and theoretical renaissance. In this talk, we will discuss novel ways to use quantum mechanics and provide several experimental applications of quantum tomography for proton-proton and heavy-ion collision experiments at the CERN Large Hadron Collider. We will discuss application of this model-independent analysis technique for Z bosons, dijets and quarkonia. The first observation of an unexpected correlation of spin and momentum in the experimental data will also be presented.

#### Via Zoom:   https://mit.zoom.us/j/95129215697

Thibaut Houdy1,2

KATRIN: from neutrino mass to Dark Matter

Abstract:
The KATRIN (Karlsruhe Tritium Neutrino) experiment investigates the kinematic endpoint of the tritium beta-decay spectrum to determine the eﬀective mass of the electron anti-neutrino. The collaboration reported its ﬁrst limit on the neutrino mass in fall 2019 with mν <1.1 eV (90% CL) followed by the ﬁrst sub-eV limit in March this year. Its unprecedented tritium source luminosity and spectroscopic quality make it a unique instrument to also search for physics beyond the stan-dard model such as sterile neutrinos.

The TRISTAN project aims at detecting a keV-sterile neutrino signature by measuring the en-tire tritium beta-decay spectrum with an upgraded KATRIN detection and read-out system. One of the greatest challenges is to handle the high signal rates generated by the strong activity of the KATRIN tritium source while keeping a good energy resolution and stability over time. Therefore, a novel multi-pixels silicon drift detector and read-out are being designed to handle rates up to 100 MHz with an energy resolution of 200 eV (FWHM) at 10 keV.

During my talk, the KATRIN experiment and its latest results will be introduced. Then the TRISTAN project, the assembly and the commissioning of the ﬁrst module will be presented, focusing on the latest results from a 47-pixels module inserted in the KATRIN Monitor Spectrometer. The challenges of modeling the entire tritium spectrum to look for a sterile neutrino signature will be discussed. Finally, the possibility of using the TRISTAN detector to look for solar axions in the IAXO experiment will be mentioned.

1Max-Planck-Institut für Physik, F·hringer Ring 6, D-80805 München, Germany
2Physik-Department, Technische Universität München, D-85747 Garching, Germany

#### Via Zoom:   https://mit.zoom.us/j/95129215697

William Cairncross, Harvard University

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