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 Particle Seminar Series
 Particle Seminars Spring 2010 View Printable Version

## Tentative Schedule

### January 20

Speaker: Colin Anderson, Yale University

Abstract:

Many current generation and planned oscillation experiments are searching for electron neutrino appearance.  These experiments must contend with the background posed by neutral current single $\pi^0$ (NC 1$\pi^0$) production. If one the two photons from the $\pi^0$ decay fails to be detected, the $\pi^0$ may be misidentified as a single electron--the sought after signal in such oscillation searches. In order to maximize their sensitivity to such parameters as the mixing angle $\theta_{13}$ or the CP-violating phase $\delta_{CP}$, rigorous constraints on the $\pi^0$ background will have to be established. However, the predictions of the myriad models of single pion production vary widely and previous measurements are relatively scant.  A measurement of the absolute NC 1$\pi^0$ cross section will prove valuable in constraining both models of production as well as the background to $\nu_e$ appearance searches.  Since releasing the results of its principal oscillation analysis, the MiniBooNE experiment has focused on using its enormous set of recorded neutrino and antineutrino interactions to produce multiple cross section measurements. Among these measurements are absolute differential cross sections for NC 1$\pi^0$ production for both neutrinos and antineutrinos, which will be presented here. These cross sections are the first absolute and first differential cross sections for NC 1$\pi^0$ production and they encompass samples of neutrino and antineutrino events that are roughly an order of magnitude larger than any other sample at O(1 GeV).  Liquid Argon Time Projection Chambers (LArTPCs), an emerging neutrino detector technology with robust particle identification capabilities, will also be discussed.

### January 27

Speaker: Georgia Karagiorgi, MIT

Abstract:

MiniBooNE is a short-baseline experiment located at Fermilab, sensitive to neutrino oscillations for large neutrino mass-squared splittings. These oscillation searches have been motivated by the 3.8 sigma excess of electron antineutrino events in a muon antineutrino beam, observed by the LSND experiment in 1995. This talk will present recent oscillation results from MiniBooNE. The implications for the LSND excess will be discussed within the context of sterile neutrino oscillation models.

### February 24

Speaker: Yoshinori Kurimoto, Kyoto University

Abstract:

It is essential for the neutrino oscillation experiments to understand the neutral pion production via neutrino-nucleus neutral current interaction in the neutrino energy region of a few GeV. In the seminar, we present the study of neutral current neutral pion production from muon neutrinos scattering on a polystyrene (C8H8) target in the SciBooNE experiment. We measure the inclusive cross section of neutral current neutral pion production and pion kinematics distribution. The results agree with the Rein-Sehgal model, which is generally used for the Monte Carlo simulation by many neutrino oscillation experiments. In addition, we also present recent study about the coherent pion production.

### March 3

Speaker: Ryan Patterson, Caltech

Abstract:

The confirmation of non-zero neutrino mass has opened up a host of questions about the neutrino sector.  After a brief review of what we know and don't know, I describe current and upcoming experimental efforts, in particular those directed at measuring a possible non-zero value for the mixing angle theta_13.  I present in detail the latest results from MINOS and the design and physics potential of the NOvA long-baseline neutrino experiment currently under construction at Fermilab (near site) and Ash River (far site).

### March 10

Speaker: Teppei Katori, MIT

Abstract:

Using high-statistics MiniBooNE CCQE data, the muon-neutrino CCQE differential cross section on carbon is measured. This is the first measurement for the double differential cross section in CCQE interaction, and is the most complete information one can obtain from muon-kinematics-based CCQE cross section measurements. Our measurement can be used to study nuclear effects in neutrino interactions, which is critical input for future long baseline neutrino oscillation experiments.

### March 24

Speaker: Toby Marriage, Princeton University

Abstract:

The Atacama Cosmology Telescope (ACT) project represents a new class of millimeter-wave surveys that probe cosmology from inflation to late-time structure formation. ACT's arcminute-scale temperature measurements, corresponding to spatial frequencies up to ell ~ 10000, will improve constraints on the form of the inflationary potential (n_s), the sum of neutrino masses, primordial helium abundance, and the rms of the cosmological matter distribution (sigma_8). Many constraints result from complementary probes within the ACT dataset: CMB power spectra, CMB lensing, galaxy clusters, etc. In this talk I will present the first results from ACT on the CMB power spectrum, galaxy clusters discovered through the Sunyaev-Zel'dovich effect, and extragalactic sources. I will also describe future polarization measurements in the Atacama which will extend primary CMB measurements into the post-Planck era.

### March 31

Speaker: Bo Jayatilaka, Duke University

Abstract:

Confirming or excluding the existence of a standard model (SM) Higgs boson remains one of the highest priorities of experimental particle physics. Indirect constraints indicate the most likely mass of a SMHiggs boson is lower than 150 GeV. The Fermilab Tevatron has delivered more than 8/fb of integrated luminosity to the CDF and D0 experiments and prospects for seeing evidence or excluding the existence of alow-mass Higgs boson remain good. In this talk I will introduce the main search channels at CDF as well as discussing the tools and strategies in place, focusing on the ZH->llbb channel. I will conclude by summarizing the status of these searches as well as the most current combination of Higgs boson search results from both CDF and D0.

### April 14

Speaker: Scott Wakely, University of Chicago

Abstract:

Accurately measuring the primary cosmic-ray electron flux at high energies is one of the trickier activities in cosmic-ray astrophysics. I'll discuss some of the issues involved with making these measurements, briefly review some of the most recent results in the field, and describe future instruments currently under construction for the purpose of further hunting these vexing particles.

### April 28

Speaker: Jodi Cooley, Southern Methodist University

Abstract:

The Cryogenic Dark Matter Search (CDMS) collaboration has pioneered the use of ionization and athermal phonon signals to discriminate between signal (nuclear recoil) and background (electron recoil) events in germanium crystals cooled to ~50 mK.  Timing, ionization yield, and position information allow us to maximize discovery potential by achieving a background expectation of less than one event. The final runs of the CDMS II experiment in the Soudan Underground Laboratory located in northern Minnesota include an additional ~600 kg-days of raw exposure of our germanium detectors.  I will present results from the recently unblinded analysis of this data, report on the significance of these new results, and discuss the implications for future dark matter direct detection experiments.