INPA

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 (America/Los_Angeles) | 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.
