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Super-Soft X-ray Sources (SSS) are a small class of X-ray sources characterised by a blackbody-like spectrum of effective temperature 30-100 eV (several 10^5 K) and luminosities above 10^36 erg/s. Owing to their softness, galactic SSS are more difficult to observe and interpret because of high galactic extinction and uncertain distances, respectively. While a small number of permanent SSS are known since the 80s, novae have been predicted to pass through a phase of SSS emission that has indeed been observed with, e.g., ROSAT, BeppoSAX, or ASCA. Attempts of spectral modeling of nova SSS spectra ranged from blackbody fits to most refined local thermodynamic equilibrium (LTE) and non-LTE atmosphere modeling, but the low resolution of CCD spectra allows no unique constraint of spectral parameters of complex models. The X-ray grating spectrometers on board XMM-Newton and Chandra allow much more detailed analysis of SSS spectra and, as always in nature, the truth is much more complicated than believed. I will first present historic observations and attempts of interpretation, and then show the grating spectra with the details. A large variety in grating spectra of canonical SSS spectra and those of novae emerged, and I will show approaches how to find trends and to explain some commonalities. Spectral modeling is currently not possible, but I will present and discuss some approaches
Event Time
1100 - 1200hrs
Venue
Bowland North SR 23
Speaker
Jan-Uwe Ness (European Space Astronomy Centre, Madrid)
LHC measurements and searches are usually conducted with a particular theory model in mind, but can also have unexpected implications for alternative scenarios. Especially in the absence so far of smoking gun signals of new physics at the LHC, reinterpreting combinations of many "preserved" data analyses in this way, applied to more general models of beyond-SM physics has become a big business. I will show uses of the Rivet & Professor MC toolkits for reinterpretation of electroweak, top quark, and BSM search data in this way, particularly in first results from the TopFitter, Contur, and Gambit fitting groups, and how these studies can also inform future experimental measurements.
Event Time
13:45 - 14:45
Venue
Physics C36
Speaker
Andy Buckley, Glasgow
We have measured the mobility and limiting terminal velocity of electron bubbles sliding along vortex lines in superfluid 4He for a broad range of temperatures (0.1 - 1 K). This allows dissipative processes at small length scales to be probed, which can include drag exerted by an excess density of excitations in the vicinity of the vortex core; the scattering and generation of Kelvin waves and solitons; condensation of 3He impurity atoms onto vortex cores. We have also used this technique to probe the dynamics of agitated vortex arrays and the corresponding timescales for relaxation back towards a rectilinear array, providing new insight into the decay of quantum turbulence at short length scales.
Event Time
3pm-4pm
Venue
C36 Physics
Speaker
Dr Paul Walmsley, University of Manchester
Massive stars formed in atomic hydrogen reservoirs
Event Time
1130 - 1230hrs
Venue
C36 Physics
Speaker
Michal Michalowski (University of Edinburgh)
Neutrino oscillation has been clearly established via the study of solar, atmospheric, reactor and beam neutrinos. Combination of these results requires the existence of (at least) three-neutrino mixing. Great progress has been made in measuring the parameters governing neutrino oscillation. The latest generation of reactor anti-neutrino experiments; Double Chooz, Daya Bay and RENO, have been incredibly successful at finally measuring the smallest of the three mixing angles, theta13. These experiments observe a disappearance of the anti-neutrinos emitted by the cores of commercial nuclear reactors at distances of ~1 km. The Double Chooz experiment consists of two identical detectors; one near, to precisely measure the neutrino spectrum and flux from the two cores of the Chooz B power plant (Ardennes, France), and one far, to measure the neutrino disappearance. In the first phase of the experiment, with only the far detector in operation, the experiment reported the first hint of theta_13 in 2011. This first observation was confirmed with precise measurements from Daya Bay and RENO in 2012. Double Chooz is now in its final phase, with both detectors running since 2015. A relative measurement, between near and far detectors, results in an improved precision as a large part of the original systematic uncertainties are cancelled out. I will describe the Double Chooz experiment; in particular the electronics and data acquisition, review the different and complementary methods of obtaining theta_13, and discuss the latest released results.
Event Time
13:45 - 14:45
Venue
Physics C36
Speaker
Dr Jaime Dawson, APC Paris
Electroweak production measurements at the LHCb experiment LHCb is able to make important contributions in areas of research beyond LHCb's original remit in beauty and charm physics. I will present the latest LHCb measurements of forward Electroweak Boson Production in proton-proton collisions. These results provide unique constraints on the parton distribution functions which describe the inner structure of the proton, probing a region of phase space at low Bjorken-x where the other LHC experiments have limited sensitivity. I will also present measurements of cross-section ratios, which can provide precision tests of the Standard Model. I shall also present a measurement of the forward-backward asymmetry (A_FB) in Z boson decays to two muons. This result allows for precision tests of the vector and axial-vector couplings of the Z boson, providing sensitivity to the effective weak mixing angle (sin^2(theta_W^eff)). The A_FB distribution visible in the LHCb acceptance is particularly sensitive to this angle, as the forward phase-space probed at LHCb means that the initial state quark direction is better known than in the central region probed by the other LHC detectors. This reduces uncertainties in extracting sin^2(theta_W^eff) from A_FB, and allows LHCb to make the most precise determination of sin^2(theta_W^eff) at the LHC. I shall also discuss (some of) the future potential of these and related measurements at LHCb.
Event Time
13:45 - 14:45
Venue
Physics C36
Speaker
Dr Will Barter, Manchester
I will review our recent progress in the generation of kHz relativistic electron beams driven by single-cycle laser pulses. This new source, providing 5 MeV electrons with few femtosecond duration has great potential for studying ultrafast structural dynamics via ultrafast electron diffraction (UED). I will also show recent UED results showing intriguing lattice dynamics in single crystal Silicon.
Event Time
3pm-4pm
Venue
C36 Physics
Speaker
Prof. Jérôme Faure, ENSTA ParisTech
Neutrinos with ANNIE & WATCHMAN
Event Time
13:45 - 14:45
Venue
Physics C36
Speaker
Matthew Malek, Sheffield
Solid-state quantum emitters are required for quantum information protocols relying on the storage, manipulation, and transmission of the information encoded in single photons through optical cavities and waveguides. Semiconductor quantum dots are particularly promising quantum light sources that can allow both the investigation of fundamental physics phenomena on a chip and quantum technology applications [1]. I will discuss the implementation of quantum dot nanostructures to create simultaneously bright and pure, on-demand, single-photon sources in engineered nanophotonic devices in gallium arsenide [2] and hybrid silicon/III-V materials [3]. I will present different photonic geometries for controlling light propagation, brightness and spontaneous emission rate, based on circular grating and ring cavities. Finally, I will focus on the comparison between highly engineered structures and disordered photonic crystal waveguides, showing efficient light confinement and optical sensing on a silicon nitride platform in the visible range of wavelengths [4]. References: [1] O. Gozzano, G.S. Solomon, Toward optical quantum information processing with quantum dots coupled to microstructures, Journal of the Optical Society of America B 33, C160 (2016) [2] L. Sapienza, M. Davanco, A. Badolato, K. Srinivasan, Nanoscale optical positioning of single quantum dots for bright and pure single-photon emission, Nature Communications 6, 7833 (2015). [3] M. Davanco, J. Liu, L. Sapienza, C.-Z. Zhang, J.V. De Miranda Cardoso, V. Verma, R. Mirin, S. W. Nam, L. Liu, K. Srinivasan, A heterogeneous III-V/silicon integration platform for on-chip quantum photonic circuits with single quantum dot devices, arxiv.org/abs/1611.07654 (2016). [4] T. Crane, O.J. Trojak, L. Sapienza, Anderson localisation of visible light on a nanophotonic chip, arxiv.org/abs/1605.08614 (2016).
Event Time
3pm-4pm
Venue
C36 Physics
Speaker
Dr Luca Sapienza, University of Southampton
Two members of the Physics Dept staff, Dr Louise Willingale and Dr Licia Ray, will be speaking about their careers to date. This event will provide a fascinating insight into the life of the professional scientist, and how to get started in the field, and will be a must-attend for anyone considering a career of this type. Join us for this great opportunity to meet other members of the Department and discuss career paths. Refreshments provided, everyone is welcome! For more info contact Sarah Badman
Event Time
13:00 - 14:00
Venue
Bowland North SR6
Speaker
Dr Louise Willingale and Dr Licia Ray, Lancaster University
Join us to meet Physics researchers and talk about whatever you're working on or would like to work on in the future, including summer/undergraduate research projects. Refreshments will be provided and everyone is welcome!
Event Time
13:00 - 14:00
Venue
C36, Physics
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Day | Week | Month | Year | Upcoming