Upcoming Particle Seminars*
September 19
Speaker: Markus Klute, Massachusetts Institute of Technology
Title: "Observation of a new boson with mass near 125 GeV with CMS"
Abstract:
On July 4, 2012, the discovery of a new boson, with mass around 125 GeV
and with properties compatible with those of a standard-model Higgs
boson, was announced at CERN. I will present the results of the search
with the CMS detector. The search is performed in five decay modes: gg,
ZZ, WW, tau tau and bb. An excess of events is observed above the
expected background, with a local significance of 5.0 standard
deviations signaling the production of a new particle.
October 3
Speaker: Matthew Moulson
Title: "The NA62 experiment: Rare kaon decays at the CERN SPS"
Abstract:
The flavor-changing neutral-current decays K → π νν¯ are highly
sup-pressed in the Standard Model, while their rates can be predicted
with minimal theoretical uncertainty. The branching ratios for these
decays are therefore sensitive probes of the flavor sector of the
Standard Model, providing constraints on the CKM unitarity triangle that
are complementary to those from measurements of B-meson decays.
However, the tiny branching ratios and challenging experimental
signatures for these decays make them notoriously difficult to measure.
The goal of NA62, an experiment at the CERN SPS, is to detect ∼ 100K+ →
π+νν¯ decays with an S/B ratio of10:1 in two years of data taking
starting in 2014. The experiment will make use of the NA48 calorimeter
and beamline and a host of new detectors, which are now under
construction. In 2007 and 2008, the new collaboration took data with the
NA48 detector to measure RK , the ratio of rates for K → µν to K → µν,
the value of which could potentially reveal evidence for super-symmetry.
After a brief discussion of NA62’s measurement of RK , I will describe
the physics of the K → πνν¯ decays and the NA62 measurement strategy and
physics program.
October 17
Speaker: Marlene Doert, Technical University of Dortmund
Title: "Deconvolution of data - solving inverse problems in (astro-) particle physics"
Abstract:
Inverse problems appear in any kind of indirect measurement process, be
it the task of understanding a particle collision event by tracking its
secondary particles, or to determine the energy of a cosmic event by
measuring the light produced in the atmosphere by the resulting particle
cascade. I will discuss these so-called "ill-posed" problems and
present a statistical analysis technique which is commonly used to solve
them: the method of unfolding or deconvolution of data. Besides the
generic approach and the inherent difficulties such as oscillating
solutions and the need for regularization methods, I will present the
novel unfolding program TRUEE, which has been implemented by the
astroparticle physics group at TU Dortmund. TRUEE offers a numerical,
event-based solution of inverse analysis problems and makes use of the
Tikhonov regularization method. I will illustrate the functionality of
the program by presenting analysis examples from the MAGIC gamma-ray
telescopes and the IceCube neutrino detector.
October 24
Speaker: Kazuhiro Terao, Massachusetts Institute of Technology
Title:
"Searching for Ѳ13 Using Neutron Capture on Hydrogen in Double Chooz"
Abstract:
Double Chooz is a reactor antineutrino experiment built to measure Ѳ 13.
The experiment uses two detectors at different baselines (400 m and 1
km) to precisely measure the disappearance of ῡₑ 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 Ѳ 13 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. Furthermore, because of the very
different nature of the backgrounds and systematic uncertainties, a
combination of the Hydrogen and Gd analysis may help us better constrain
the value of Ѳ 13. In this seminar, I present the current status and
preliminary results from the Hydrogen analysis in Double Chooz.
December 10 - MONDAY
Speaker: Michael Sutherland, Louisiana State University
Title: "Ultra-High Energy Cosmic Rays and The Pierre Auger Observatory"
Abstract:
Ultra-high energy cosmic rays are the most energetic particles in the
universe but their properties are poorly understood. While most are
charged, their actual composition is unknown. There also is little
knowledge of their extragalactic sources due to deflection of their
trajectories in intervening magnetic fields. The extremely low flux of
these particles, less than 1 particle km ${^-2}$ yr$^{-1}$ above
$10^{18}$ eV, necessitates indirect detection methods using the
extensive air showers initiated when the cosmic ray primary interacts
with air molecules within the atmosphere. Located in the high pampa of
Argentina, the Pierre Auger Observatory is the largest cosmic ray
detector in the world and combines two traditional air shower detection
techniques: air fluorescence telescopes and water Cherenkov ground-based
detectors. These allow precision measurements of the energy spectrum
and the arrival directions, as well as data to infer the chemical
composition of the cosmic ray primaries. I will discuss recent results
from the Observatory as well as my contributions on magnetic corrections
for source identification.
December 17 - MONDAY
Speaker: Jonathan Eisch, University of Wisconsin
Title: "Measurement of the spectrum and composition of cosmic rays with IceTop and IceCube"
Abstract:
The IceCube Neutrino Observatory and its associated surface array,
IceTop, form a fully-integrated three-dimensional cosmic ray detector.
IceTop, located on the surface of the South Polar ice sheet at 3000 m
above sea level, is sensitive to the electromagnetic component of cosmic
ray air showers, while IceCube, buried 1400 m below the surface, is
sensitive to deeply penetrating high-energy muons. By combining
information from the two detectors, it is possible to reconstruct both
the energy and mass of primary cosmic rays. In combination, the
detectors are sensitive to cosmic rays with energies between 1 and 100
PeV, a transition region in the cosmic ray spectrum known as the
"knee." In this talk I will present an unfolding technique used to
determine the average energy-dependent mass composition of cosmic rays
in this energy range. The measurement of cosmic ray composition may
shed light on the origin of cosmic rays in the knee region.
*Please continue visiting the Department of Physics web site for seminar updates.
