### December 6, 2006

Speaker:
Prof. Mike Shaevitz, Columbia University
Title:
Neutrino Oscillations and the Double Chooz Reactor Experiment
Abstract:
The recent confirmations of the solar and atmospheric neutrino oscillation signals have changed this area of particle physics from addressing anomalies to measuring the properties of neutrinos and their mixings. Several key questions now need to be answered: Are neutrinos Majorana particles being both particle and antiparticle? Are there sterile neutrinos that don’t participate in the standard weak interaction? Does neutrino mixing exhibit CP violation analogous to the quark mixing? The first question can be investigated by searching for neutrinoless double beta decay. The second question is primarily being addressed by the MiniBooNE experiment. For the third question, the next important step is to measure the unknown mixing angle that couples the solar and atmospheric mass eigenstates. If this angle is shown to be greater than about 5 degrees, future long-baseline neutrino experiments could investigate CP violation. The Double Chooz reactor experiment will be the first experiment to have sensitivity to probe for oscillations at this level of mixing. In this talk, I will go over the phenomenology and current knowledge of neutrino oscillations followed by a plan for future experiments. The Double Chooz reactor neutrino experiments will then be described as the next step for neutrino oscillation measurements

### November 29, 2006

Speaker:
Dr. Miguel F. Morales, Harvard University
Title:
Radio Observations of the Epoch of Reionization
Abstract:
Highly redshifted 21 cm neutral hydrogen emission from the Epoch of Reionization (EOR) is a unique cosmological probe, and planned low frequency radio observations could revolutionize our understanding of structure formation and the emergence of the first luminous objects. However, EOR observations are complicated by strong foreground contamination and stringent instrumental requirements. In this talk, I will review the observational signatures of the Epoch of Reionization and how the faint 21 cm emission can be extracted from the foreground signals, and describe the Mileura Widefield Array - Low Frequency Demonstrator (MWA-LFD) my colleagues and I are constructing in Western Australia.

### November 15, 2006

Speaker:
Dr. Milind Diwan, Brookhaven National Laboratory
Title:
Progress on a Future U.S. Long Baseline Program
Abstract:
Dr. Diwan will describe progress on a future accelerator based long baseline program aimed at CP violation in neutrino physics.

### November 8, 2006

Speaker:
Dr. Chad Finley, University of Wisconsin
Title:
IceCube and Neutrino Astronomy at the South Pole
Abstract:
The IceCube Neutrino Observatory in Antarctica is a kilometer-scale detector operating deep within the ice at the geographic south pole. When completed, it will comprise over 4000 optical modules deployed between 1.5 km and 2.5 km below the surface, where the Cerenkov radiation of charged particles created in neutrino interactions can be observed through clear ice. Its enormous size is dictated by its principal mission: to detect high energy neutrinos from the extreme astrophysical environments which are known to produce TeV photons and are suspected of producing EeV cosmic rays. Neutrino observations of objects such as active galactic nuclei and gamma-ray bursts will offer unique insights into nature's highest-energy accelerators. In this talk I will discuss the major physics goals of kilometer-scale neutrino observatories; results from the predecessor experiment AMANDA; and the status and outlook for IceCube, which is presently operating and observing neutrinos with 10% of the detector already deployed.

### October 31, 2007

Speaker:
Amy Connolly
Title:
"Closing in on Ultra-High Energy Neutrinos with the Radio Detection Technique"
Abstract:
The Antarctic Impulsive Transient Antenna (ANITA) is a balloon experiment that aims to detect neutrinos with energies above 1018 eV (1 EeV) for the first time by detecting the radio Cherenkov signal produced by neutrino interactions in the Antarctic ice. Neutrinos in this energy regime are expected to be produced in the interaction of cosmic rays with the cosmic microwave background. ANITA will fly at the end of this year, during the 2006-2007 Austral summer. I will present results from the ANITA-lite test flight, and discuss the status of preparations for the upcoming flight. In addition, I will describe two next-generation radio detection experiments under development, one in a salt formation and another on the Antarctic Ross Ice Shelf, that are designed to move beyond the discovery stage and measure a sample of ultra-high energy neutrinos that is large enough to study their rich properties.

### October 18, 2006

Speaker:
Dr. Andy Haas, Columbia University
Title:
"Search for Split SUSY using Stopped Gluinos at the D0 Experiment"
Abstract:
A generic prediction of Split Supersymmetry is a long-lived gluino. Some of these new particles will lose enough energy through ionization to actually stop in the D0 calorimeter. I search for the decay of these stopped gluinos, which would look like a energetic jet coming from within the calorimeter itself. The simulation of the signal, estimations of the dominant backgrounds, and results from ~300 pb-1 of D0 RunII data will be presented.

### October 11, 2006

Speaker:
Prof. Sacha Kopp, University of Texas at Austin
Title:
First Results from the MINOS Neutrino Oscillation Search
Abstract:
The Main Injector Neutrino Oscillation Search (MINOS) experiment at Fermilab looks for the disappearance of muon neutrinos across a 735 km baseline from Fermilab to Soudan, MN. A conventional, horn-focused muon neutrino beam is delivered to 2 magnetized iron calorimeters, one at Fermilab and one in Soudan. The experiment has accumulated $1.4 \times 10^{20}$~protons on target from May, 2005 until February, 2006. The energy spectrum of the neutrino beam can be varied, allowing a search of oscillation parameters in the range indicated by atmospheric neutrino experiments. Results, recently submitted to Physical Review Letters, will be summarized.

### October 4, 2006

Speaker:
Dr. Michael Prouza, Columbia University
Title:
Cosmic rays and Gamma-ray bursts: A proven connection
Abstract:
As the construction of the southern site of the Pierre Auger Observatory progresses, new links between the physics of ultra-high energy cosmic rays and some traditional astronomical topics have emerged, and these links are being used to improve data analysis. Three examples of such astronomical topics will be discussed in this presentation: the test of the fluorescence camera alignment using star tracks; the study of previously unobserved variations in the night sky brightness using the fluorescence cameras; and especially the discovery of an optical counterpart of Gamma Ray Burst 060117 with FRAM -- a robotic telescope that is primarily designed for atmospheric monitoring at the Auger site (A&A 454 (2006) L119). I will also give an update on the status of the Observatory and summarize recent physics results.

### September 27, 2006

Speaker:
Prof. Tony Zee, U.C. Santa Barbara
Title:
Attempts to Understand the Neutrino Mass Matrix

### September 19, 2006

Speaker:
Dr. John Jones, Imperial College
Title:

Trigger Hardware in CMS - Present & Future
Abstract:

The current CMS trigger architecture is based on a two-tier approach; the Level-1 trigger controls readout of the detector based on coarse-grained information about an event, is predominantly hardware-based, using a combination of custom ASICs and FPGAs and operates with a fixed latency. The Higher-Level trigger is PC and software based, using a partial reconstruction approach to filter the data down to the recording rate of 100Hz. In this seminar the hardware architecture of the Level-1 trigger is introduced, focusing on trigger throttling in the CMS tracker and the architecture of the calorimeter trigger. The use of modern programmable logic with high speed optical links is discussed, emphasising its use for data concentration in the Global Calorimeter Trigger. Looking forward to Super-LHC, a possible new architecture of the CMS Level-1 trigger system is discussed, incorporating additional information from a new pixel detector. Issues with high-speed reconstruction and on-detector data rate reduction are discussed. Alternative uses of current trigger hardware are also considered, such as the use of high-speed processing hardware in medical imaging projects.

### September 13, 2006

Speaker:
Dr. Thomas Gadfort, University of Washington
Title:
Search for single top quark production at D0
Abstract:
A measurement of the single top quark cross section provides the only way to directly measure the CKM matrix element |Vtb| thereby testing the unitarity of the CKM matrix. Violations of unitarity would indicate possible new physics such as a fourth generation of quarks. I will present the latest results from the D0 single top quark search with 360 pb-1 of RunII data as well as preliminary results with 1 fb-1 using the matrix element technique to enhance the expected signal significance. The matrix element analysis technique attempts to reconstruct each event at the parton level process and then uses leading order matrix elements to distinguish single top from the W+jets and ttbar backgrounds. I will also discuss our general search strategy including online triggering, background estimating using data and Monte Carlo, and b jet identification using a neural network. Finally, assuming the current analysis sensitivity, I will comment on the amount of data required for discovery given a Standard Model cross section.

### September 6, 2006

Speaker:
Dr. Stan Lai, University of Toronto
Title:
Search for Associated Higgs Production with Top Quark Pairs at CDF
Abstract:
The search for the elusive Higgs boson is an important goal for hadron collider experiments. The Tevatron at Fermilab collides protons with antiprotons at energies of 1.96 TeV and is currently the only collider that has the potential to produce Higgs bosons. I present the first search at a hadron collider of associated Higgs production with top quark pairs. Though such a signal has a very small cross section, the final event topology is very distinct, involving four jets originating from b-quarks. 95% C.L. limits are set on the cross section for this process. This measurement complements other searches for the Higgs boson using different production channels at CDF.