The Sudbury Neutrino Observatory (SNO) provided the first clear evidence of solar neutrino flavour change. The success of SNO resides in its ability to measure, with heavy water, both the flux of solar electron neutrinos and the total neutrino flux using two different reactions, the charge-current and neutral-current reactions, in addition to the electron-scattering interaction which also occurs in light water Cherenkov detectors. The SNO experiment was divided into three phases, each one using a different method for detecting neutrons produced in the neutral-current interaction, thus providing three different measurements of the total flux of solar neutrinos. In preparation for the final combined analysis of the whole SNO data set, the data of the two first phases are re-examined, after lowering the energy threshold from 5.5 MeV to 3.5 MeV. At this threshold, a good understanding of the detector and backgrounds is crucial to separate the neutrino events and associate them with a reaction. The additional information at low energies allows for an extended analysis of the various neutrino oscillation mechanisms and hypothesis tests of the solar standard model. The constraints on the oscillation parameters are shown, as obtained from both the low-energy SNO analysis and when the latter is combined with other solar and non-solar neutrino oscillation experiments.

In this talk, I will present results from the Neutral Current Detector (NCD) phase of the Sudbury Neutrino Observatory (SNO). In this phase of the experiment, the total 8B solar neutrino flux is measured independently from the other phases using an array of 3He proportional counters (NCDs) immersed in one kiloton of heavy water. The proportional counters detect the neutrons produced when all flavours of neutrinos interact (through the neutral current) with the deuterons in the heavy water. Comparing the number of neutral current events with the number of charged-current events (sensitive to only the electron neutrino flavour and measured by an array of PMTs) gives a measure of the solar neutrino oscillation mixing parameters.

Tokai-to-Kamioka long baseline neutrino experiment (T2K experiment) is one of the next generation neutrino experiments that will intensively study oscillations of muon neutrinos. A beam of muon neutrinos produced by a newly constructed 50 GeV proton synchrotron accelerator at Tokai in Japan that travel 295 km to the Super-Kamiokande detector will have one to two orders of magnitude higher intensity than past experiments. With this facility we aim to measure disappearance oscillation of muon neutrinos and search for undiscovered electron neutrino appearance signal with the highest-ever sensitivities. A set of detectors will be placed at 280 m downstream of the proton target, where the properties of the neutrino beam and neutrino interactions will be measured before neutrinos have a chance to oscillate to other flavors. Time projection chambers (TPC’s), together with fine grained detectors (FGD’s), make up the primary tracker in the ND280 detector giving the kinematical information of muons, as well as other secondaries, produced by neutrino interactions in FGD’s. The TPC has been designed and constructed by a collaborating work of Canadian and European groups. Its design has been finalized and the construction is underway toward installation in the T2K experiment scheduled in fall 2009. This presentation will describe the physics requirements, the design, and the construction status of the TPC modules.

Flavour will play a crucial role in understanding physics beyond the Standard Model. Progress in developing a future programme to investigate this central area of particle physics has recently passed a milestone, with the completion of the conceptual design report for SuperB -- a novel technological solution for colliding electrons and positions at centre-of-mass energies around the Υ(4S) (~10.6 GeV) with extremely high luminosities (>O(1036cm-2s-1) in a low background environment.  Such a research tool, opens the exciting possibility of a programme of high statistics heavy flavour physics (B and D mesons and tau leptons) that has sensitivity to physics beyond the Standard Model by measuring subtle effects in CP-violating asymmetries and in rare decay branching fractions and kinematic distributions affected by new heavy particles in the loops of second order diagrams.  It will provide unique and complementary data for interpreting results from the LHC and indirect access to energy scales beyond those directly probed at the LHC.  The time scale for this effort has first collisions occurring in 2014 with the physics programme completed before an ILC is expected to begin collecting data.

The Fine-Grained Detector (FGD) is an element of T2K's near detector.  Its purpose is to provide target mass where neutrinos interact and track the particles produced in the interactions.  It is constructed from 0.96x0.96x184 cm3 scintillator bars extruded with a hole down the centre and coated by a thin layer of titanium dioxide.  A wavelength shifting fiber is inserted in the central hole.  One end of the fiber is coupled to a Multi-Pixel Photon Counter (MPPC) and the other end is mirrored.  The fast MPPC pulses (< 1 ns rise time, 9 ns fall time) are stretched into slower pulses (120 ns rise time, 240 ns fall time) and sampled at 50 MHz during 10 microseconds by the AFTER ASIC.  The 10 microsecond sampling time is chosen to encompass the beam spill plus two muon decay constants, in order to detect Michel electrons from pions stopping in scintillator bars.  We report on the performance of the FGD detector elements.  Beam test measurements show that minimum ionizing particles produce at least 15 photo-electrons.  Despite the slow sampling frequency, a timing resolution better than 3 ns has been achieved for MIPs by fitting the rise time of the pulse, which fulfills the detector requirements.

The Large Hadron Collider will collide 7 TeV proton beams with the intent of studying the Standard Model of Particle Physics and searching for physics beyond.  The Liquid Argon Forward Calorimeter (FCal) of the ATLAS detector is an important component in the studies mentioned above.  The FCal contains both electromagnetic and hadronic modules and in 2003, a beam test was conducted to obtain the energy calibration.  Using the H6 beam line at CERN, the beam test was performed to investigate the response of the FCal to both electrons and pions in the energy range of (10-200) GeV.  A simulation of the beam test was incorporated into the ATLAS software framework to study the beam test data.  Results of the Geant4 simulation are compared to the data for the linearity and the resolution of the FCal, over the above mentioned energy range.

We present recent work done to develop software for a novel method of parameter estimation.  In a standard likelihood or chi-squared fit, the data is compared to an analytical theoretical prediction. For many models, it becomes quite difficult to write an analytic expression for the convolution of the physics model of interest, and the detector response function. This means many researchers may resort to either using numerical convolution with a great reduction in the speed of calculations and the overall fitting process, or they may choose to use a simplified instrument response function using only functions which allow for easy evaluation of the convolution integrals. This second approach can lead to fit biases which hinder precision measurements.  We present a novel method for avoiding the problems associated with analytic convolution. First we use high statistics Monte Carlo simulation to generate a template for the data we wish to fit. The Monte Carlo events contain enough truth information to allow our software to reweight the events correctly as we vary the physical parameters in the fit. This allows one to perform an exact fit when the underlying distributions are understood, even if one cannot easily write an analytical convolution of all of the underlying probability density functions.  We will briefly present some results based on feasibility studies of measuring the frequency of neutral B meson oscillations with dilepton decays in the BaBar experiment.

The VERITAS ground-based gamma-ray detector, comprising four 12m telescopes equipped with 499-phototube imaging cameras, has been operational since early 2007. It has achieved its design sensitivity and a comprehensive science program, including observations of active galactic nuclei and supernova remnants, a galactic plane survey, and gamma-ray burst follow-up observations, has started. Here we will report on the status of the instrument and some of the science results from the first year of observations.

Water Cerenkov and liquid scintillator neutrino detectors are primarily sensitive to electron anti-neutrinos, via charged-current interactions on the hydrogen nuclei in these materials.  By contrast, the large neutron excess of a heavy nucleus like Pb acts to Pauli-block p→n transitions induced by electron anti-neutrinos, making it primarily sensitive to electron neutrinos.  This channel is expected to show the most interesting effects of flavour-swapping and spectral splitting due to MSW-like collective neutrino-neutrino interactions in the core of the supernova, the only place in the universe where there is a sufficient density of neutrinos for this to occur.  The data will provide a test for θ 13 ≠0 and an inverted neutrino mass heirarchy, and the ratio of 1-neutron to 2-neutron events will provide a measure of the temperature of the cooling neutron star.  HALO is a detector of opportunity proposed for SNOLAB, which will utilize 80 tons of surplus Pb blocks, together with the neutral-current detectors from the SNO experiment and the SNO data acquisition system, to provide a low-cost, low-maintenance, long-lived, high-lifetime detector.  A supernova at 10 kpc would result in 43 neutrons in the absence of collective ν-ν interactions, and many more in their presence.  A future upgrade to 1 kiloton would be sensitive to supernova anywhere in our galaxy.

Dark Matter Experiment with Argon and Pulse Shape Discrimination (DEAP) is an experiment, which aims to detect Dark Matter with scintillation light produced by nuclear recoil in liquid argon. DEAP-1 is a detector with 7 kg target volume, currently located in SNOLAB. In this talk, I will be discussing the triple coincident gamma calibration and the discrimination power between neutron-like and electromagnetic events.

The PICASSO dark matter search experiment employs Special Bubble Detectors (SBD) that consist of superheated liquid freon droplets (active material) dispersed uniformly throughout a water-based gel matrix. The droplet size distribution is related to the method of detector fabrication and can serve as feedback to the fabrication process, allowing quality control. In addition, understanding the distributions of droplet sizes will help in the data analysis by providing a better understanding of the distributions of detector signal amplitudes. This presentation will discuss techniques we have developed at Laurentian University to measure and analyze the droplet size distributions of detector gel samples using microscopy and digital imaging.

Since the discovery of the solar neutrino problem by Ray Davis in the late 1960s, different experiments have been designed to understand the discrepancy between measured and predicted fluxes of electron neutrinos coming from the Sun and to verify if this phenomenon can be explained by the oscillation of neutrinos due to a possible mismatch between flavour and mass eigenstates. Among these experiments is the Sudbury Neutrino Observatory (SNO), which provided the first clear evidence of solar neutrino flavour change. The success of SNO resides in its ability to measure with heavy water both the flux of solar electron neutrinos and the total neutrino flux using the charge-current and neutral-current interactions, in addition to the electron-scattering reaction which also occurs in light water Cerenkov detectors. The SNO experiment was divided into three phases, each one using a different method for detecting neutrons produced in the neutral-current interaction, thus providing three different measurements of the total flux of solar neutrinos. The third phase primarily relies on the deployment of proportional counters to measure the events produced via the neutral-current reaction, while statistical techniques are used for the two other phases. This allows a decoupling of the systematic uncertainties that could be used in a combined analysis to reduce the total uncertainty on the measured neutral-current flux. The presence of these counters creates however some asymmetries in the detector that must be considered to avoid a large increase of fiducial volume and energy uncertainties.

We present the search for the radiative leptonic decay modes B+→e+νeγ and B+→μ+νμγ using data collected by the BaBar detector at SLAC.  This analysis uses a novel technique in which the accompanying B is exclusively reconstructed, providing cleaner kinematic information on the signal's missing energy and high momentum photon and lepton.  With the approximately 465 million B meson pairs produced by this B-factory (corresponding to an integrated luminosity of ~ 423 fb-1), the predicted Standard Model branching fraction of these rare decay modes may finally be within reach to produce a measurable signal.  The combination of this unprecedented large data set and this promising new technique will allow a tighter measurement of the B→lνγ branching fraction in a model-independent way.

The τ−→ηπ−π+ π−ν τ decay with the η → γγ  mode is studied using 384 fb−1 of data collected by the BABAR detector at the PEP-II asymmetric-energy e+e− storage rings operated at the Stanford Linear Accelerator Center. The branching fraction is measured to be (1.60 ±0.05 ±0.11)× 10−4. It is found that τ−→ f1(1285) π−ν τ → ηπ−π+ π−ν τ  is the dominant decay mode with a branching fraction of (1.11 ± 0.06 ± 0.05) × 10−4. The first error on the branching fractions is statistical and the second systematic. In addition, a 90% confidence level upper limit on the branching fraction of the τ−→ η′(958) π−ν τ  decay is measured to be 7.2 × 10−6.

The Longitudinal Structure Function (FL) is the most difficult component to measure of the Deep Inelastic Scattering (DIS) Cross Section.  The ZEUS experiment at HERA is making the first direct measurement of this elusive function.  Once extracted, FL will give insight into the Gluon Parton Distribution Function (PDF) in the Proton, which would be a valuable asset to all experiments dealing with deeply inelastic parton interactions.  This contributed talk will discuss the experimental method used by the ZEUS collaboration to extract FL and will include the latest results.

The Enriched Xenon Observatory (EXO) proposes to measure the effective neutrino mass by observing neutrinoless double beta decay of xenon 136 into barium 136 in a large time projection chamber (TPC).  An original way to possibly eliminate the number of background events from natural radioactivity in EXO would be to use lasers and the current knowledge of the barium ion spectroscopy to optically observe the daughter nucleus.  Such technique would be a unique advantage over other neutrinoless double beta decay experiments and possibly the only way to convince every members of the scientific community of the existence of the decay. The talk will concentrate on the procedure to perform barium tagging and on the current apparatus used to observe a cloud of barium ions in gas.

With the long-anticipated turn-on of the LHC this summer, particle physics enters a new era of discovery which promises to shed light on electroweak symmetry breaking, dark matter, and what lies beyond the Standard Model.  This talk will survey recent developments in phenomenology at the energy frontier.

Electroweak singlets may couple only through Higgs exchange to Standard Model particles. Models with electroweak singlets therefore provide interesting minimal dark matter models. We discuss possible signatures of these models in cosmic gamma rays.

The Large Hadron Collider (LHC) located at CERN near Geneva will begin operating before the end of 2008 at low luminosity.  With a design luminosity of 10^34/cm^2/sec and a centre-of-mass energy of 14 TeV for proton-proton collisions, this collider will allow the exploration of particle physics at the electroweak symmetry breaking scale.  One of the detectors which will study the collision products is ATLAS, A Toroidal LHC ApparatuS.  With the ATLAS detector, it will be possible to investigate the validity of the Standard Model of particle physics and other models beyond.  Canadian physicists have been actively participating in this international project.  Their participation includes simulations of exotic physics, detector construction, radiation hardness studies, beam conditions monitoring, real-time radiation field monitoring and development of the high-level trigger.

I will discuss how the various explanations for the large transverse polarization in certain rare B decays can be tested.

“The direct search for evidence of Weakly Interacting Massive Particle (WIMP) dark matter continues among the forefront activities of experimental physics”. The PICASSO project is one of these experiments that use Superheated Droplet Detector (SDD) for direct search in the spin dependent channel. I will present the status of detector fabrication and R&D including the necessary (background and calibration measurements) before their installation for direct dark matter detection.

PICASSO consists of several bubble detectors looking  for weekly interacting massive particles (WIMP) which are thought to be the main component of the 20% of dark  matter present in the universe. Because of the very small probability of interaction and detection we need to know the shape of our backgrounds very precisely. In this presentation I will talk about the ongoing progress on the neutron, gamma and alpha calibrations necessary to understand these backgrounds.

ALPHA is an international collaboration based at CERN’s Antiproton Decelerator. Our long-term goal is to test the symmetry between matter and antimatter via a precision comparison of the well-studied hydrogen atom with its antimatter counter-part, antihydrogen. Since the start of the construction of the experiment in 2006, rapid progress has been made towards stable trapping of antihydrogen atoms. In this talk, we will discuss the details of our trapping techniques, including recent physics results on the containment of charged particles in a combined trap [1], production of antihydrogen in a reduced magnetic field [2], and radial compression [3] and diagnosis [4] of antiproton plasmas.  References: [1] Phys. Rev. Lett 98, 023402 (2007); [2] J. Phys. B 41, 011001 (2008); [3] submitted to Phys. Rev. Lett; [4] accepted for Phys. Plasmas (2008).

Recent experiments, including SNO and SuperK, have definitively shown that neutrinos have mass.  Measuring neutrino oscillations, these experiments are only senstive to difference in mass squared and not directly to the neutrino mass scale.  Neutrinoless double beta decay, a process in which two neutrons simultaneously decay to protons and electrons, is directly sensitive to neutrino mass.  The EXO collaboration aims to carry out a sensitive search for the neutrinoless double beta decay of 136Xe.  Time projection chamber technology, with measurement of both ionization and scintillation signals and coupled with a spectroscopic laser tag, is being developed to optimize the ability to reject backgrounds and maximize sensitivity to signal events.  The current status of the EXO experiment efforts will be provided with emphasis on the research and development towards a gas-phase detector.

The DØ experiment at the Fermilab Tevatron proton-antiproton collider has recorded an integrated luminosity greater than 3 fb−1.  DØ is a multi-purpose detector that probes a wide spectrum of physics topics within the Standard Model, such as top-quark production and properties measurements, QCD, W and Z gauge bosons studies, and b-quark physics.  The DØ experiment also allows for searches for the Higgs boson as well as physics beyond the Standard Model, such as super symmetry and extra dimensions.  In this talk, I will present some of the recent highlights of the DØ physics program.

Many extensions of physics beyond the Standard Model predict the  existence of a charged Higgs boson.  A new search for the production of charged Higgs boson decaying to a top and a bottom quark in proton-antiproton collisions was performed.  Results obtained from the analysis of nearly 1~$\rm fb^{\rm -1}$ of data collected by the DZero experiment at Fermilab will be presented.

Standard Model is the most comprehensive present day precision theory of electro-weak phenomena. Nonetheless, many key questions in particle physics and cosmology remain unanswered. The measurements at LHC at CERN are expected to provide some of the answers over the next few years, but may also raise new questions. The International electron-positron Linear Collider (ILC) is being planned as the next high-energy world facility for particle physics. Precision experiments at the ILC will be essential in unambiguously interpreting LHC physics discoveries. ILC will also be a discovery machine on its own. ILC physics will require detector performance not achievable by existing technology. The project status and the detector challenges will be described with focus on ILC Canada group R&D activities.