INPA

Bradford Welliver (LBNL) - Results and Current Status of the SuperCDMS Soudan Experiment
2017-03-24 12:00 - 13:00 (America/Los_Angeles)
The SuperCDMS experiment is a dark matter search that utilizes an array of 15 patterned Ge crystals, called iZIPs with a total mass of 9kg. SuperCDMS has completed operations at the Soudan Underground Laboratory and reported results on low-mass (M 10 GeV/c^2) WIMP search analysis with 1700 kg-days of exposure using 10 of the iZIP detectors is nearing completion. This talk will present an overview of the SuperCDMS detector technology, recap the low-mass search results and discuss the analysis strategy and status of the high mass WIMP search.

Jessie Muir (Michigan) - Unbiasing cosmology on the largest scales
2017-03-17 12:00 - 13:00
One of the most exciting areas of research in cosmology is the effort to extract information about fundamental physics from observations of the universe on large scales. With the advent of increasingly large cosmological datasets (and correspondingly small statistical uncertainties), future progress in the field will fundamentally be determined by our ability to understand and account for systematic errors. In this talk, I’ll discuss two projects which further that ability: a study of how reliably we can separate primordial and late-time contributions to large-angle features of the the Cosmic Microwave Background (CMB) and the development of a blinding strategy to prevent experimenters’ bias from influencing the Dark Energy Survey’s cosmological analysis.

Quentin Riffard - Direct detection of dark matter with the DarkSide program
2017-03-13 12:00 - 13:00
A large number of astrophysical and cosmological observations at different scales supports the existence of a cold dark matter component in the Universe. At the Universe scale, this component is uniformly distributed and represents roughly 26% of the total mass-energy density of the Universe. The Weakly Interacting Massive Particle (WIMP), a generic particle, is one of the leading dark matter particle candidates: a massive particle interacting only through weak and gravitational interactions. This candidate is supported by the so-called “WIMP miracle” and could also be supported in particle physics by supersymmetric models. At the Milky Way scale, dark matter forms a static halo surrounding our galaxy. The relative motion of the solar system through the dark halo produces a flux of WIMP on Earth. Through the weak interaction, WIMP could interact with ordinary matter producing nuclear recoils (NR) by elastic scattering. In the last two decades, a large experimental effort has been deployed by international collaborations in order to probe a direct detection of NR from WIMP-nucleus interactions. In this experimental context, multi-tone noble liquid TPC are good candidate for the dark matter searches. The DarkSide program is a step approach program aiming to build a large TPC filled with liquid argon (LAr). The first part of this presentation focuses on the potential of LAr as a target for dark matter searches, on the latest results from the DS-50 detector and the perspectives of the DarkSide program: the DS-20k detector. For a complete understanding of LAr data, the characterisation of several parameters is fundamental such as the scintillation efficiency for NR and the pulse-shape parameter for the NR/ER discrimination is fundamental. In order to improve the knowledge on these parameters, the ARIS collaboration built a small LAr double-phase TPC. A first data taking with mono chromatic neutrons was performed in Orsay (France) in last October. The second part of this presentation presents a status of the ARIS data analysis and a discussion of the strategy to extract the parameters.

Sandra Miarecki - Earth vs. Neutrinos: first measurements of neutrino absorption in the Earth and the muon neutrino-to-nucleon cross section above 1 TeV with the IceCube Detector
2017-03-10 12:00 - 13:00 | 50A-5132- Sessler, 50A-5132 Sessler Conference Room, CA
Bio:
Sandy Miarecki is a retired Air Force test pilot, PhD graduate of the University of California-Berkeley, and an affiliate member of LBL after completing her dissertation research at LBL. She is currently an assistant professor of physics at the US Air Force Academy in Colorado Springs.
The IceCube Detector at the South Pole was constructed to measure the flux of high-energy neutrinos and to try to identify their cosmic sources. In addition to these astrophysical neutrinos, IceCube also detects the neutrinos that result from cosmic ray interactions with the atmosphere. These atmospheric neutrinos can be used to measure the total muon neutrino-to-nucleon cross section by measuring neutrino absorption in the Earth for the first time. The measurement involves isolating a sample of 10,784 Earth-transiting muons detected by IceCube in its 79-string configuration. The cross-section is determined using a two-dimensional fit in measured muon energy and zenith angle and is presented as a multiple of the Standard Model expectation as calculated by Cooper-Sarkar, Mertsch, and Sarkar in 2011. A multiple of 1.0 would indicate agreement with the Standard Model. The results of this analysis find the multiple to be 1.30 (+0.21 -0.19 statistical) (+0.40 -0.44 systematic) for the neutrino energy range of 6.3 to 980 TeV, which is in agreement with the Standard Model expectation.

Martina Gerbino (NORDITA) - Three Neutrinos in Cosmology (to Say Nothing of Laboratory)
2017-03-03 12:00 - 13:00
Neutrinos are the only standard model particles of unknown mass. Thus, measuring their mass is one of the leading goals in fundamental physics. Cosmology currently provides the tightest bounds on the sum of the neutrino masses and the possibility that next generation experiments can provide a detection looks promising. Then, further questions would have to be addressed, such as the neutrino hierarchy and the neutrino nature. In this talk, I will discuss the treasure trove of information about massive neutrinos that we can collect from different cosmological probes. I will stress the importance of extending our interest to laboratory searches, such as kinematic measurements and neutrino less double-beta decay experiments, for going beyond measuring the neutrino mass. Finally, I will choose a different angle and show how massive neutrino unknowns can affect the constraints on inflationary models.

Lauren Ice (ASU) - Measurement of the Two-Photon Exchange Contribution to Elastic Lepton-Proton Scattering with the OLYMPUS Experiment
2017-02-27 12:00 - 13:00 | 50B-4205
The OLYMPUS experiment measured the two-photon exchange contribution to elastic electron-proton scattering, which is thought to be the most likely candidate to resolve the discrepancy observed between polarized and unpolarized measurements of the proton electric-to-magnetic form factor ratio. To deterimine the two-photon exchange contribtuion, OLYMPUS measured the positron-proton to electron-proton elastic scattering cross section ratio over a wide range of four-momentum transfer from 0.6 < Q2 < 2.2 (GeV/c)2 and virtual photon polarizaton from 0.456 <  < 0.978. The two-photon exchange contribution is correlated to the deviation of the cross section ratio from unity.
In 2012, the OLYMPUS experiment collected over 4 fb−1 of e+p and e−p scatter-ing data using electron and positron beams incident on a hydrogen gas target. The scattered leptons and protons were measured exclusively with a large acceptance spec-
trometer. OLYMPUS observed a slight rise in σe+p/σe−p of at most 1-2% over the Q2 range. This talk will discuss the motivations, experiment, analysis method, and the preliminary results for the cross section ratio as measured by OLYMPUS.

Raul Hennings Yeomans (UCB)
2017-02-24 12:00 - 13:00
Recent progress on the next generation double beta decay experiment with low-temperature macro-calorimeters (CUPID)
The Cuore Upgrade with Particle IDentification, or CUPID, is a proposed next generation double-beta decay experiment that requires a low-threshold optical photon light detector. The use of a secondary bolometer as a light detector is being investigated since, $alpha$-particles (the main background of CUORE-0) could be tagged by comparing the heat and light signals for each event, given that the two betas from a neutrinoless double beta event would produce both heat and light (Cherenkov light in the case of TeO$_2$) while $alpha$ events would produce only heat in the absorber. A baseline resolution of at least 20~eV is required in order to achieve a rejection factor of 99.9% of the $alpha$ background. I will review latest progress on CUPID, particularly the development of low-Tc superconducting Transition Edge Sensor technology.

Scott Daniel (University of Washington) - Deterministic chi^2 Exploration to Find Credible Limits Faster than by Bayesian Sampling
2017-02-17 12:00 - 13:00 | 50A-5132- Sessler, 50A-5132 Sessler Conference Room, CA
Once data has been collected, it is desirable to be able to quickly transform that data into statements about the values and corresponding uncertainties — the “confidence limits” or “credible limits” — of the physical parameters underlying the data. Traditionally, this problem is treated probabilistically. This process can be time consuming, as enough samples need to be drawn that the distribution of samples converges to the Bayesian posterior distribution of the likelihood in parameter space. We propose an alternative scheme based on the likelihood ratio test, minimizing a cost function that incentivizes exploration of parameter space points within the credible limit but far from previously explored points. Testing on toy likelihood functions with realistic non-Gaussian properties, we find that this scheme converges to the same credible limit as the usual Bayesian methods but requires an order of magnitude fewer evaluations of the likelihood function. Our code is publically available over GitHub.

Benjamin Schmidt (LBNL) - CUORE Commissioning
2017-02-03 12:00 - 13:00

Marcelo Alvarez -Simulating Large Scale Structure Observables from Reionization to the Present
2017-01-20 12:00 - 13:00 | 50A-5132- Sessler, 50A-5132 Sessler Conference Room, CA
The next generation of large scale structure surveys will map out the universe in unprecedented detail. Transformative techniques in computational astrophysics are emerging as the optimal ways to extract information from these surveys, with realistic and routine full sky simulations finally within reach. I will describe a new pipeline for efficiently simulating high resolution maps of the sky from the radio to x-ray and from reionization to the present. I will conclude with what questions are likely to be answered in the next decade.

Initial results from the Majorana Demonstrator - By Alan Poon - LBNL
2017-01-13 12:00 - 13:00 | 50A-5132- Sessler, 50A-5132 Sessler Conference Room, CA
Neutrinoless double-beta decay experiments play a major role in the search for lepton number violation and the Majorana nature of the neutrino mass. The MAJORANA Collaboration has assembled two modules of high-purity Ge detectors to search for neutrinoless double-beta decay in 76-Ge at the Sanford Underground Research Facility in Lead, South Dakota. One of the primary goals of the MAJORANA DEMONSTRATOR (MJD) is to establish the required background and scalability of a Ge-based, next-generation, tonne-scale experiment. Commissioning of MJD started in 2015 and its two detector modules are taking data. I will discuss the initial results on the search for neutrinoless double-beta decays and dark matter from the commissioning run and the first physics run of Module 1.

Alex Lowell (USB/SSL) - TBA
2016-12-16 12:00 - 13:00 | INPA Common Room, 50-5026

Probing Dark Matter with Radio Surveys
2016-12-09 12:00 - 13:00 | INPA Common Room, 50-5026
Julian Munoz
Probing Dark Matter with Radio Surveys
A significant part of dark matter could be compact, in particular in the form of primordial black holes. I will review the signatures of primordial black holes, both in the form of gravitational-wave events and as gravitational lenses of fast radio bursts. Alternatively, a WIMP-y dark-matter component could interact with baryons. I will explain how these interactions cause heating of the baryons, becoming observable in the 21-cm line prior to the epoch of reionization.
