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HEP Seminars

30 Mar 2020

UCL HEP Seminars 2008

Prof. Alain Blondel (University of Geneva)

Status of MICE

Harry van der Graaf

Alternative ATLAS Upgrade?

Dr Robert Flack

Results from Neutrino '08

In May 2008 I attended the conference Neutrino08 in Christchurch New Zealand and gave a plenary talk about the latest results from NEMO 3 and SuperNEMO. There were approximately fifty plenary talks and 100 "beer and pizza" talks in the evening. I will give a summary of the main plenary talks.

Simon Bevan

Ultra High Energy Neutrino Astronomy with ACoRNE

An overview of UHE neutrino astronomy will be presented emphasising on the exciting new results from ACoRNE. The ACoRNE collaboration has successfully been taking data from the Rona array since December 2005. Here the progress in match filters, co-incident pulse finding tools, and neural networks will be discussed, showing the development of a successful reduction and analysis package used on the Rona data. The results of this analysis will be presented as the UK's first acoustic limit.

Prof. Gary Varner (University of Hawai'i)

Microwave Radio Detection of UHE Air Showers

Extensive air showers deposit such large amounts of energy into the atmosphere that even relatively weak emission mechanisms may be observable at considerable distances. It has been known since the 1960's that UHE Cosmic Ray interactions lead to a concurrent radio emission, though the process was not well understood or characterized at the time. In recent years there has been renewed interest in this lower frequency radio mechanism, attributed to geosynchrotron emission during shower evolution. However since this emission is "beamed" onto the ground, observation is similar to traditional ground array observations of the shower particles. By contrast, in analog to distant shower observation via Nitrogen fluorescence, molecular bremsstrahlung emission of shower electrons leads to isotroptic radiation at microwave radio frequencies. While incoherent emission may be detectable at kilometer scale distances, accelerator measurements indicate that at least partial coherence is present in such cascades, significantly enhancing the fiducial acceptance of this technique. Since the atmosphere is almost completely transparent to microwave and operation is insensitive to light background or weather, an order of magnitude better livetime may be expected compared with fluorescent observation, with potentially lower systematic energy uncertainty. A preliminary satellite dish-based system has been operated in Hawaii and a follow-on prototype system is described that will be deployed at the Auger Observatory in spring 2009.

Prof. Yoshitaka Kuno (Osaka University)

Physics of Lepton Flavor Violation of Charged Leptons and an Experimental Proposal to Search for Muon to Electron Conversion at J-PARC

Lepton flavor violation of charged leptons has attracted much interest from theorists and experimentalists since it would have potentials to get important hints for new physics beyond the Standard Model, such as SUSY-GUT and/or SUSY-Seesaw models. In particular, a process of muon to electron conversion in a muonic atom is considered to be one of the best to search for. In this talk, a new experimental proposal to search for muon to electron conversion with sensitivity of less than 10^{-16} at J-PARC in Japan will be presented.

03/10/2008 : Dr. Chris Hays (University of Oxford)

Search for High-Mass Resonances in CDF Dimuon Data.

Neutral resonances have a long and illustrious history, and could well provide the next big discovery in particle physics. I present a new search for high-mass neutral resonances in the CDF dimuon data, the most sensitive such search to date. The analysis applies the novel technique of probing the inverse mass spectrum, for which the detector resolution is constant in the search region. The results are interpreted in terms of spin 0, 1, and 2 resonances, using sneutrino, Z', and graviton models, respectively.

26/09/2008 : Jonathon Coleman (SLAC)

The Status of mixing and CP searches in the charm sector.

During 2007 the Flavor Factories surprised the physics community with unexpected results in charm-mixing. Since this time there has been several confirmations of this phenomena. I will present an overview of recent experimental results from for the $D0$ meson oscillating into its own anti-particle, (or vice versa).

19/09/2008 : Fabrizio Palla (INFN-Pisa)

Motivation and possible architechtures for a Level-1 track Trigger in CMS and the SuperLHC

13/06/2008 : Carlo Carloni Calame -- 4pm Maths 500

Electroweak radiative corrections to Drell-Yan processes at hadron colliders

The status of the electro-weak radiative corrections to Drell-Yan processes is summarized. Their impact on observables which are important for Tevatron and LHC physics is discussed. Particular emphasis will be given on their implementation in the event generator Horace.

30/05/2008 : Dave Waters (UCL) -- E7

Weighing Up the Weak Force : W Boson Mass and Width Measurements from CDF Run II

The W boson, carrier of the weak nuclear force, is the least well measured of the Standard Model's force carriers. Precision measurements of the mass and the lifetime of the W boson provide a stringent test of the Standard Model and, indirectly, allow us to probe the physics that may lie beyond the Standard Model. I present recent direct measurements of the W boson mass and width from the CDF experiment, both of which are now the single most precise measurements in the world. I discuss several of the challenges involved in performing these analyses, and outline the prospects for such measurements in the future.

16/05/2008 : Aidan Robson (University of Glasgow)

Higgs Searches at CDF

2008 is going to be significant for Higgs physics: we expect to reach 95%CL sensitivity to a 160GeV Higgs with the combined Tevatron data. I will talk about CDF's Higgs->WW analysis, focusing on techniques, set it in the context of CDF's low-mass Higgs searches, and give an outlook for the next few years.

09/05/2008 : Ken Peach (John Adams Institute for Accelerator Science -- University of Oxford and Royal Holloway University of London)

A new accelerator for advanced research and cancer therapy

Although Fixed-Field Alternating Gradient Accelerators were invented in the 1950s, they have never made any significant impact, the technology being superseded by the synchrotron. However, interest has recently been revived, particularly in Japan, where "proof of principle" proton FFAGs have been built. More recently, a new concept - the "non-scaling FFAG" - has been advanced, which offers the prospect of developing relatively compact, high acceleration rate accelerators for a variety of purposes, from neutrino factories and muon acceleration to cancer therapy. However, there are formidable technical challenges to be overcome, including resonance crossing. We have recently been awarded funding in the UK to construct a demonstrator non-scaling FFAG at the Daresbury laboratory (EMMA, the Electron Model with Many Applications), and to design a prototype machine for proton and carbon ion cancer therapy (PAMELA, the Particle Accelerator for MEdicaL Applications). I will describe some of the motivations for developing this new type of accelerator, and discuss the status of the EMMA and PAMELA projects.

02/05/2008 : Terry Sloan (Lancaster University)

Cosmic Rays and Global Warming

In this seminar I will explore the proposed link between changes in cloud cover and the changes in the rate of ionization in the atmosphere produced by the effects of solar magnetic activity on cosmic rays. I will briefly review the mechanism by which this could cause global warming,comparing it with the more conventional view of the cause arising from the increased the concentration of greenhouse gases. I will go on to describe our searches for evidence to corroborate the cosmic ray cloud cover link.

18/04/2008 : Fabio Maltoni (Université catholique de Louvain)

The ttbar invariant mass as a window on new physics

I explore in detail the physics potential of a measurement of the ttbar invariant mass distribution at the Tevatron and the LHC. First, the accuracy of the best available predictions for this observable are considered with the result that in the low invariant mass region the shape is very well predicted and could be even used to perform a top mass measurement. Second, I study the effects of an heavy s-channel resonance on the ttbar invariant mass distribution, in a model independent way and outline a simple three-step analysis towards a discovery.

14/03/2008 : Fedor Simkovic (Comenius University Bratislava)

Double Beta Decay: History, Present and Future

The properties of the neutrinos have been the most important issues in particle physics, astrophysics and cosmology. After neutrino oscillations discovery, search for neutrinoless double beta decay (0v-decay) represents the new frontiers of neutrino physics, allowing in principle to fix the neutrino mass scale, the neutrino nature (the Dirac or Majorana particles) and possible CP violation effects. Many next generation 0v-decay experiments are in preparation or under consideration. In this presentation the development in the field of nuclear double beta decay is reviewed. A connection of the 0v-decay to neutrino oscillations and other lepton number violating processes is established. The light and sterile neutrino exchange mechanisms as well as R-parity breaking mechanisms of the 0v-decay are analyzed. The problem of the reliable determination of the 0v-decay nuclear matrix elements is addressed. The possibility of boson neutrino and partially boson neutrino is studied in light of the 2v-decay data. The perspectives of the field of the double beta decay are outlined.

07/03/2008 : Dr. Tim Namsoo

A prelude to some ZEUS results to be shown at DIS08

The DIS08 conference is fast approaching and is to be hosted by UCL and Oxford University, in the UCL campus in the week starting the 7th April. The ZEUS collaboration, that operated a general purpose detector on the HERA electron-proton collider in Hamburg, and to which the UCL HEP group belongs, are preparing to send a number of results to DIS08. The number and range of these results makes covering them all in a single seminar unfeasible so instead, a subset of results, in which the speaker is involved, will be discussed. These topics will include the measurement of the longitudinal proton structure function, the energy dependence of the photoproduction cross section, studies involving the multiplicity and momentum spectra of charged hadrons in jets and three- and four-jet cross sections in photoproduction. The talk will not include final results on all of these topics but instead will motivate and discuss various aspects of the measurements at a level not possible during the conference itself due to stricter time constraints.

29/02/2008 : Dr. Chris Parkes

The LHCb Vertex Locator and the LHCb upgrade - or finishing the bicycle wheel spokes and turning it into a vespa.

LHCb is the dedicated heavy flavour physics experiment at the LHC, and is currently being commissioned. Arguably the single most critical element of the detector is the silicon vertex locator. The unique design has 40 micron pitch silicon strip detectors operated in vacuum only 8mm from the LHC beam and retracted and reinserted between each fill. It is the only LHC detector yet to have seeen beam data - the partially assembled final system having been tested in the CERN SPS. The design, testing, alignment and performance of this detector are discussed. The discovery potential of the experiment, or the measurement of the characteristics of new physics discovered during the first phase, can be significantly enhanced through the upgrade of the experiment to run at higher luminsoity. The plans for the LHCb upgrade are presented.

22/02/2008 : Dr. Steve Boyd (Warwick)

T2K - The Next Generation.

It is now a well established fact that the weak and the mass eigenstates of neutrinos are not identical. As a consequence we can observe transitions from one neutrino species to another. Over the past decade neutrino experiments have measured most of the parameters describing neutrino oscillations with ever increasing accuracy. One parameter so far eludes measurement, the so-called mixing angle theta_13. T2K is one of the next generations experiments. While it aims to improve the knowledge of some of the other parameters, its main objective is the measurement of theta_13, which is responsible for muon to electron neutrino transitions. This angle may hold the key to study CP violating effects in the lepton sector of the SM. The seminar will summarise the current status of neutrino oscillation studies, and will outline the future contributions of the T2K Experiment.

08/02/2008 : Dr. Lisa Falk-Harris

The Double Chooz Reactor theta_13 Experiment

The Double Chooz reactor experiment is the next step for neutrino oscillation measurements: It will measure, or limit, the last undetermined PMNS mixing angle, theta_13, down to an order of magnitude below the current limit. Deploying two identical detectors, one near the reactor cores and one at a distance of 1.05 km, will permit us to control the systematics to the level required to reach a sensitivity of sin^2 2theta_13 ~0.03. I will give a brief summary of our present knowledge of the neutrino mixing parameters, and a motivation for new reactor experiments. I will then describe the design and status of the Double Chooz experiment and of its detector components. Finally, I will discuss systematics, expected sensitivity and the schedule for installation and data-taking.

01/02/2008 : Dr James Libby (Oxford)

The precise determination of the unitarity triangle angle gamma: LHCb and CLEOc

The LHCb experiment will be introduced. The precise determination of gamma is a cornerstone of the LHCb physics programme; the motivation for this will be presented. Decays of the type B+ -> DK+, where the D is a D0 or a D0bar decaying to the same final state, allow a theoretically clean measurement of gamma. The prospects with LHCb for modes where the D decays to 2, 3 and 4 bodies are discussed. This discussions introduces the importance of measurements of the strong parameters of the relevent D-decays to allow precise determination of gamma and the crucial role played by quantum correlated e+e- -> psi(3770) ->D0D0bar data currently being collected by CLEOc. The CLEOc measurements essential to a precise determination of gamma are presented.

25/01/2008 : Prof. Stephen Watts (Manchester)

Data Mining and Visualisation

There are more ways to represent ones data than by using graphs, histograms and scatterplots. There are many new techniques which exploit computer technology that enable one to visualise and explore multidimensional data. The seminar will explain these ideas, show how they are related to data mining, and apply them to particle physics data analysis.

24/01/2008 -- NB: Thursday 24th in Cruciform B.09 : Prof. Peter Rowson (Stanford Linear Accelerator)

A Novel Approach to Neutrinoless Double Beta Decay - EXO.

The "Enriched Xenon Observatory", or EXO, is an ongoing experimental and R&D program to employ a new technique for the search for neutrinoless double-beta decay. The decay and detection medium is xenon enriched in the 136 isotope. A phase I experiment known as EXO200, using 200 kg of xenon enriched to 80% xenon 136, is presently being installed at the WIPP underground facility in Carlsbad, New Mexico, and is scheduled to begin data taking at the end of the coming summer. In a two year run, this liquid xenon TPC experiment will observe and study two-neutrino double beta decay in xenon for the first time, and should exceed presently available sensitivity for the neutrinoless mode. In parallel, an R&D program is underway for a future multi-tonne detector employing a laser-fluoresence based daughter-nucleus tagging scheme that should be able to reach sensitivities to the effective neutrino mass in neutrinoless double beta-decay down to the 10 meV range.

18/01/2008 : Prof. Bob Nichol (Portsmouth)

Seeing Dark Energy (slides)

Nearly 10 years ago, astronomers discovered the expansion of the Universe was accelerating driven by a mysterious quantity now know as "Dark Energy". Explaining the existence and properties of dark energy is a major challenge for physicists. In this seminar, I will review the evidence for dark energy (including my own research) and our present understanding of dark energy. I will conclude the talk with an overview of future dark energy research which will dominate cosmology for the next decade.