NPAC (Nuclear/Particle/Astro/Cosmo) Forum

Recent analyses of the anti-neutrino flux from reactors has suggested that shot baseline reactor neutrino experiments saw only about 92.7% of the expected flux, a result is commonly referred to as the Reactor Neutrino Anomaly. In this talk I will present an independent analysis of this anomaly and the underlying nuclear physics determining the shape and magnitude of reactor neutrino spectra. In this analysis, we find that corrections due to forbidden beta-decays of fission fragments result in significant changes to the shape of the spectrum. These changes, which have not been taken into account in earlier anomaly analyses, leads to more anti-neutrinos being emitted at low (<2.5 MeV) and high energies (>4.5 MeV), and fewer anti-neutrinos between 2.5-4.5 MeV. The uncertainty in the shape of the spectrum also increases when the forbidden transitions are included. The measured spectrum from the near detector at Daya Bay should greatly help to reduce these uncertainties.
Host: 
Karsten Heeger
Speaker: Anna Hayes-Sterbenz Los Alamos National Laboratory

 

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Room and Building: 
4274 Chamberlin Hall
The launch of the Fermi Gamma-ray Space Telescope in 2008 has ushered in a new era for the study of the extreme Universe. In addition to ground-breaking improvements in sensitivity and angular resolution, providing the deepest and sharpest view of the high-energy gamma-ray sky, Fermi also has opened a whole new window in the time domain. With a large field of view allowing complete coverage of the sky every 3 hours, Fermi can "catch" rare and exciting transient events in addition to following the behaviour of all gamma-ray emitters as a function of time. In this talk, I will review some of the surprises uncovered by Fermi on timescales from milliseconds to years and describe how these results have advanced our understanding of some of the most extreme phenomena known to astrophysics.
Host: 
Francis Halzen
Speaker: Julie McEnery Goddard GSFC, Maryland

 

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Room and Building: 
4274 Chamberlin

The first four and a half years of Fermi LAT operations have seen numerous exciting scientific results relating to many different topics, some expected and others unexpected. I will present a brief overview of the Fermi mission and the role it plays in current particle astrophysics research. Towards this end I will discuss some recent scientific highlights involving both galactic and extra-galactic sources classes. I will then spend the majority of the talk focusing on searches for signatures of particle dark matter interactions. In particular I will describe the LAT team's search for spectral lines from gamma-ray annihilation or decay, and discuss the status of claims of a line-like feature at 130 GeV near the Galactic center.

Host: 
Neilson
Speaker: Eric Charles SLAC

 

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Room and Building: 
4274 Chamberlin

Neutrino-less double beta decay may answer essential open questions in neutrino physics. While double beta decay accompanied by the emission of two neutrinos is allowed by the standard model, the neutrino-less process requires neutrinos to be Majorana particles. Detecting this decay could determine the nature of neutrinos, the neutrino effective mass, and the mass hierarchy. The Enriched Xenon Observatory (EXO) is an experimental program searching for neutrino-less double beta decay in xenon-136. The first stage of this program, EXO-200, features 200 kg of liquid xenon. The detector, located at the Waste Isolation Pilot Plant in New Mexico, has been taking data for two years. EXO-200 detected for the first time two-neutrino double beta decay of xenon, the slowest process ever measured directly. Furthermore it set a strong limit on the rate of zero-neutrino double beta decay. I will describe EXO-200 as well as prospects for the future large-scale detector nEXO.

Host: 
Halzen
Speaker: Delia Tosi Stanford University

 

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Room and Building: 
4274 Chamberlin
Thursday, March 21st, 2013
Speaker: Thad Walker U. Wisconsin-Madison

 

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Room and Building: 
4274 Chamberlin Hall
XENON100 is a dual-phase (liquid-gas) time projection chamber (TPC) containing a total of 161 kg of LXe with a 62 kg WIMP target mass, built with radiopure materials to achieve an ultra-low electromagnetic background and operated at the Laboratori Nazionali del Gran Sasso in Italy. Data from the XENON100 experiment have resulted in the most stringent limits on the spin-independent elastic WIMP-nucleon cross sections for WIMP masses above 8 GeV/c^2.

I will present the experiment and its latest dark matter search results. I will also discuss a dedicated test facility built and operated at Columbia University to measure with high precision the scintillation response of LXe to low-energy electrons and nuclear recoils of interest to dark matter direct detection experiments like XENON.
Host: 
Reina Maruyama
Speaker: Kyungeun Lim Columbia University

 

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Room and Building: 
4274 Chamberlin
Ground-based gamma-ray observatories have opened up a new window into the high-energy universe. To date, exciting results reported by experiments such as VERITAS, H.E.S.S., and Milagro include the the detection of photons from nearly 50 relativistic AGN jets at TeV energies. However, the picture of the universe beyond 1 TeV is far from complete. The origin and composition of the extra-galactic ultrahigh energy cosmic rays (UHECR) remains a central problems in astrophysics. Based on energy considerations, recent studies have argued that highly relativistic jets in AGNs are the best candidates for the sites of UHECR acceleration. Consequently, we may be able to observe >20 TeV emission from nearby AGN contrary to conventional models that predict significant attenuations of the source gamma-ray photons via the diffuse extragalactic background light. The High Altitude Water Cherenkov (HAWC) observatory, a next-generation ground-based particle shower detector will be sensitive to photon energies from 50 GeV to 100 TeV with angular resolution of 0.3 degrees at E> 1 TeV. HAWC's high duty cycle (~100%) and wide field of view (~2 sr) is ideal to test AGN as possible sites for the acceleration of UHECR. Furthermore, HAWC's observations of an orphan flare from AGN coupled with the detection of coincident neutrinos by the IceCube observatory with allow us to independently probe the acceleration of UHECR in AGN.

In this talk, I will give an overview of the mechanism for the production of high energy photons from UHECR-induced cascade emission along with an update on the current status of the HAWC observatory. I'll also present the sensitivity of the HAWC detector to TeV emission from AGN.
Host: 
Westerhoff
Speaker: Asif Imran Los Alamos National Lab

 

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Room and Building: 
4274 Chamberlin Hall

The discovery of a neutron electric dipole moment (nEDM) would provide an unambiguous indication of time violation in a fundamental system, and address one of the Sakharov conditions (CP-symmetry violation) necessary to explain the observed matter/antimatter asymmetry in the universe. Current experimental limitations on the nEDM are roughly 6 orders of magnitude above the Standard Model (SM) prediction and so searches for the nEDM provide powerful tests of physics beyond the SM. The nEDM experiment currently under construction at the Technische Universitaet Muenchen (TUM) is seeking to improve this limit up to 2 orders of magnitude. A contextual overview of the relevant physics will be given, and developments in the TUM nEDM experiment, including the recent installation of a world-record magnetically shielded room, will be presented.

Host: 
Naoko Kurahashi Neilson, WIPAC
Speaker: Michael Marino Technical University of Munich

 

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Room and Building: 
4274 Chamberlin Hall
As one of a new generation of widefield, low-frequency radio
telescopes, the Murchison Widefield Array has enormous potential to
conduct blind searches for radio transients and probe the nearby
pulsar population. We are working to develop a common framework
with the Australian Square Kilometer Array Pathfinder (ASKAP)
Variables and Slow Transients (VAST) survey to allow real-time
transient detection and characterization. I will discuss the expected
types of sources that we hope to discover with the full array and
review some of the initial results from our 32-element testbed.
Host: 
Peter Timbie
Speaker: David Kaplan UW Milwaukee, Department of Physics

 

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Room and Building: 
4274 Chamberlin Hall

Neutrinos may be Majorana particles. If so, neutrino less double beta decay processes could be observed by the next generation of bb0nu experiments. I will briefly review the state of the art, then discuss one of the most promising ideas in the field, the use of Hight Pressure Gas Xenon TPC (HPGXe) with electroluminescence gain and optical readout. A 100 kg incarnation of such a device will start operations at the Canfranc Underground Lab in Spain in late 2013 or early 2014. The technology can be extrapolated to 1 ton, and thus lead the exploration of the inverse hierarchy in Majorana landscape.

Host: 
Halzen
Speaker: Juan José Gómez Cadenas IFIC - Instituto de Física Corpuscular, Valencia, Spain

 

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Room and Building: 
4274 Chamberlin

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