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Nuclear and Particle Physics Colloquia
Mondays ~ Refreshments 3:45pm Talk: 4:15pm ~ Kolker Room, 26-414
Committee:
Allan Adams ~ William Donnelly ~ Markus Klute, Chair ~ Robert Redwine
April 1, 2013
Kazuhero Terao, MIT
"Measurement of θ13 Using Delayed Neutron Capture on Hydrogen in Double Chooz"
Double Chooz is a reactor antineutrino experiment built to measure θ13. The experiment uses two detectors at different baselines (400 m and 1 km) to precisely measure the disappearance of ¯νe from the Chooz reactor cores in Ardenne, France. Our inverse beta decay (IBD) signal is a two-fold coincidence of a prompt positron followed by a delayed neutron capture on Gadolinium (Gd). The delayed neutron capture releases 8 MeV of energy from multiple gamma rays and is easily distinguished from natural radioactive backgrounds. While delayed neutron capture on Gd is used in all the reactor-based θ13 measurements, it is also possible to detect IBD via delayed neutron capture on Hydrogen. In Double Chooz the Hydrogen detection channel has twice the signal statistics as the Gd detection channel and provides an independent data sample with which to cross-check the Gd analysis result. In this talk, I present the result of θ13 measurement from the Hydrogen analysis in the single detector phase of Double CHOOZ.
Time: 4:15 pm
Place: LNS Kolker Room, 26-414
April 8, 2013
Special LNS Colloquium
Andrei Kounine, MIT
"First results from the AMS Experiment on the International Space Station"
The Alpha Magnetic Spectrometer (AMS-02) is a general- purpose high energy particle detector which was successfully deployed on the International Space Station on May 19, 2011. It conducts a unique long-duration mission of fundamental physics research in space. To date the detector has collected over 32 billion cosmic ray events. Among the physics objectives of AMS are a search for understanding of Dark Matter, Antimatter, the origin of cosmic rays and the exploration of new physics phenomena not possible to study with ground-based experiments. First AMS physics results will be presented.
Astronaut Col. E. Michael Fincke, NASA
Photo courtesy of NASA
“AMS: The Astronauts’ Story”
In 2009, 5 NASA Astronauts and 1 ESA Astronaut were selected to fly on Space Shuttle Endeavour’s last mission to help complete construction of the International Space Station. Their number one priority was to deliver and successfully install the Alpha Magnetic Spectrometer (AMS-02), a state-of-the-art particle physics detector that uses the unique environment of space to study the universe and its origin by searching for antimatter and dark matter. This is their story.
Time: 3:00-5:00 pm
Place: 26-100
Refreshments at 2:30 PM in 26-414
April 15, 2013
Patriots Day - No Talk
April 22, 2013
Jo Dudek, Old Dominion University & Jefferson Lab 
"Gluonic Excitations in QCD"
The gross features of the low-lying spectrum of mesons and baryons have long been described in terms of constructions featuring a minimal number of 'constituent' quarks. QCD, the strongly coupled gauge theory of quarks and gluons should, on the face of it, exhibit a richer spectrum of states, including those in which the gluonic field plays an active role. One such class of states are 'hybrid' mesons and baryons in which the required quarks are coupled to an excitation of the gluonic field. I will discuss how recent advances in the application of lattice field theory methods to the problem have made possible a developing phenomenology of gluonic excitations that describes hybrid mesons and baryons.
Time: 4:15 pm
Place: LNS Kolker Room, 26-414
April 29, 2013
Stefano Profumo, UCSC 
"Fundamental Physics from the Sky: Cosmic Rays, Gamma Rays and the Hunt for Dark Matter"
Can we learn about New Physics with astronomical and astro-particle data? Understanding how this is possible is key to unraveling one of the most pressing mysteries at the interface of cosmology and particle physics: the fundamental nature of dark matter. I will discuss some of the recent puzzling findings in cosmic-ray electron-positron data and in gamma-ray observations that might be related to dark matter. I will argue that cosmic-ray data, most notably from the Pamela and Fermi satellites, indicate that previously unaccounted-for powerful sources in the Galaxy inject high-energy electrons and positrons. Interestingly, this new source class might be related to new fundamental particle physics, and specifically to pair-annihilation or decay of galactic dark matter. This exciting scenario is directly constrained by Fermi gamma-ray observations, which also inform us on astrophysical source counterparts that could be responsible for the high-energy electron-positron excess. Observations of the gamma-ray emission from the central regions of the Galaxy as well as claims about a gamma-ray line at around 130 GeV also recently triggered a wide-spread interest: I will address the question of whether we are really observing signals from dark matter annihilation, how to test this hypothesis, and which astrophysical mechanisms constitute the relevant background.
Time: 4:15 pm
Place: LNS Kolker Room, 26-414
May 6, 2013
Yasmine Amhis, LAL, Orsay France
"Where in the world is New Physics?"
Despite the enduring resillience of the Standard Model of particle physics, there remain reasons to expect that it is not a "final" theory. In particular the Standard Model can not explain either dark matter or the observed matter-antimatter asymmetry of the universe. LHCb is a general-purpose forward acceptance spectrometer at the Large Hadron Collider, dedicated to precision measurement of heavy flavour particles. Because new particles can appear virtually in the decays of heavy flavour, and thus alter its properties, such measurements are inherently sensitive to much higher mass scales that direct searches. We present here the latest LHCb results, including world-leading measurements of CP-violating and rare decay processes, and comment on the way in which these measurements constrain the properties of physics beyond the Standard Model.
Time: 4:15 pm
Place: LNS Kolker Room, 26-414
May 13, 2013
David Hertzog, University of Washington 
"Precision Muon Physics"
A snapshop of the worldwide, vibrant experimental program involving precision measurements with muons will be presented. Recent achievements in this field have greatly improved our knowledge of fundamental parameters: Fermi constant (lifetime), weak-nucleon pseudoscalar coupling (mu-p capture), Michel decay parameters, and the proton charged radius (Lamb shift). The charged-lepton-violating decay Mu --> e gamma sets new physics limits. Updated Standard Model theory evaluations of the muon anomalous magnetic moment has increased the significance beyond 3 sigma for the deviation with respect to experiment. Next-generation experiments are mounting, with ambitious sensitivity goals for the muon-to-electron search approaching 10^-17 sensitivity and for a 0.14 ppm determination of g-2. The broad physics reach of these efforts involves atomic, nuclear and particle physics communities. I will select from recent work and outline the most important efforts that are in preparation.
Time: 4:15 pm
Place: LNS Kolker Room, 26-414
May 20, 2013
Gregory Soyez, Saclay 
"Towards a standard approach to jets at the LHC"
As an introduction, I will explain the basic concept of a "jet", the proxy for partons produced in the final state of hadronic collisions. I will show that, after a long history, the last few years have seen a lot of progress made towards having fast and robust jet definitions, yielding ultimately to the current framework used at the LHC. Then, since the LHC operates at a high luminosity, additional hadronic activity known as pileup has an impact on jet reconstruction and will explain how this noise can be subtracted in practice. The framework developed to achieve this subtraction allows to reconstruct many jet properties without being sensitive to pileup.
Time: 4:15 pm
Place: LNS Kolker Room, 26-414
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