Gamma ray flares from Mrk421 in 2008 observed with the ARGO-YBJ detector

In 2008 the blazar Markarian 421 entered a very active phase and was one of the brightest sources in the sky at TeV energies, showing frequent flaring episodes. Using the data of ARGO-YBJ, a full coverage air shower detector located at Yangbajing (4300 m a.s.l., Tibet, China), we monitored the source at gamma ray energies E > 0.3 TeV during the whole year. The observed flux was variable, with the strongest flares in March and June, in correlation with X-ray enhanced activity. While during specific episodes the TeV flux could be several times larger than the Crab Nebula one, the average emission from day 41 to 180 was almost twice the Crab level, with an integral flux of (3.6 +-0.6) 10^-11 photons cm^-2 s^-1 for energies E > 1 TeV, and decreased afterwards. This paper concentrates on the flares occurred in the first half of June. This period has been deeply studied from optical to 100 MeV gamma rays, and partially up to TeV energies, since the moonlight hampered the Cherenkov telescope observations during the most intense part of the emission. Our data complete these observations, with the detection of a signal with a statistical significance of 3.8 standard deviations on June 11-13, corresponding to a gamma ray flux about 6 times larger than the Crab one above 1 TeV. The reconstructed differential spectrum, corrected for the intergalactic absorption, can be represented by a power law with an index alpha = -2.1 extending up to several TeV. The spectrum slope is fully consistent with previous observations reporting a correlation between the flux and the spectral index, suggesting that this property is maintained in different epochs and characterizes the source emission processes.Comment: Accepted for publication on ApJ

Efficient and realistic device modeling from atomic detail to the nanoscale

As semiconductor devices scale to new dimensions, the materials and designs become more dependent on atomic details. NEMO5 is a nanoelectronics modeling package designed for comprehending the critical multi-scale, multi-physics phenomena through efficient computational approaches and quantitatively modeling new generations of nanoelectronic devices as well as predicting novel device architectures and phenomena. This article seeks to provide updates on the current status of the tool and new functionality, including advances in quantum transport simulations and with materials such as metals, topological insulators, and piezoelectrics.Comment: 10 pages, 12 figure

Radiation Campaign of HPK Prototype LGAD sensors for the High-Granularity Timing Detector (HGTD)

We report on the results of a radiation campaign with neutrons and protons of Low Gain Avalanche Detectors (LGAD) produced by Hamamatsu (HPK) as prototypes for the High-Granularity Timing Detector (HGTD) in ATLAS. Sensors with an active thickness of 50~$\mu$m were irradiated in steps of roughly 2$\times$ up to a fluence of $3\times10^{15}~\mathrm{n_{eq}cm^{-2}}$. As a function of the fluence, the collected charge and time resolution of the irradiated sensors will be reported for operation at $-30^{\circ}$

Business and sustainability - a shared experience

One of the aims of university education is to prepare young people to be responsible citizens for the future. In the business world, the notion of sustainability is increasingly recognised as an important agenda. Both the Higher Education Funding Council (2008) and the Quality Assurance Agency (2014) acknowledge the critical role of higher education in educating socially responsible and ethically aware graduates. In line with this trend, many business schools have responded by offering sustainability related subjects and exploring pedagogical tools for engagement. Developing sustainability literacy (Stibbe 2011), shifting mindsets (Stubbs and Cocklin, 2008), developing critical thinking skills (Brookfield, 2011) and creating significant learning experiences for students (Dee Fink 2003) are just some examples of approaches which have proved successful. However, such initiatives and the concept of sustainability itself pose some difficult educational challenges for both educators and students. This paper explores the impact of an innovative module on business and sustainability entitled Develop Sustainable Enterprises which is offered as an option to second year students in the Business School at Canterbury Christ Church University. This is the second year that the module has run and sixty five students elected to participate. Evidence of impact has been gathered (a) using a pre and post module questionnaire; (b) through the ‘voices’ of four students who have responded to the module in different ways. Tutor reflections provide an additional viewpoint. The student contributions make this an unusual and strongly grounded presentation which will illustrate a shared experience between students and tutor on a learning journey

Marrying biomolecules and nanoparticles for diagnostics and nanomedicine

Noble metal nanoparticles (NPs) such as silver and gold NPs, at the size range of 1-100 nm have attracted enormous scientific and technological interest due to their unique optical, electronic and catalytic properties, which are largely determined by their size, shape and crystal structure. Inspired by the natural biomineralization process on using biomolecular templates to form a range of sophisticated inorganic nanostructures, our current research efforts focus on the development of bioinspired metal NPs with tunable physicochemical properties that incorporate the highly specific recognition function of biomolecules for a vast plethora of biomedical applications. Firstly, I will talk about the rational design of peptide and nucleic acid-based biomolecular templates for the biomimetic synthesis of multifunctional metal NPs with different optical properties (i.e., plasmon absorption and light emission) and integrated biofunctionalities for biosensing, imaging, delivery and therapy.1-7 Recently, we have designed a unique self-assembly DNA templates to form redox-responsive photoluminescent silver nanoclusters (NCs \u3c 2 nm in size) for two-way color change detection of free radicals (red-to-blue) and antioxidants (blue-to-red) in real time. These DNA-templated AgNCs are found to have excellent antimicrobial and toxin inhibition properties towards superbugs. Using bi-functional peptide templates, AuNCs with tunable emission color from visible to near-infrared wavelength have been successfully synthesized for targeted gene delivery and bioimaging applications. We have also employed this bioinspired approach to ‘turn’ the native protein into bioactive fluorescent sensors for small molecule drug screening and photodynamic therapy. The biocompatibility and adaptability of biomolecules involved in the synthesis enable an efficient control over nanostructures morphology (size and shape) with fine-tuned properties, resulting in low energy use and environmental impact. The second part of my talk will focus on the biofunctionalization strategies of nanometals for the development of ultrasensitive biosensors, to convert ‘invisible’ biological responses into easily measurable and observable optical outputs.8-13 By exploiting the plasmonic coupling, fluorescence and/or light scattering properties of the nanometals, we have developed a series of label-free optical nanosensors to detect a wide range of bioanalytes (e.g., vitamins, small molecule drug, etc.) and for studying important biomolecular interactions such as gene transcription, DNA mutation and enzymatic reaction. These bioassays are versatile, efficient and low-cost with high throughput sensing capability, which could culminate into tangible products useful for biomedical research and clinical diagnostics. References Tan, Y. N.; Lee, J. Y.; Wang, Daniel. I. C. J. Am. Chem. Soc. 2010, 132, 5677-5686. Tan, Y. N.; Lee, J. Y.; Wang, Daniel. I. C. J. Phys. Chem. C. 2009, 113, 10887-10895 Tan, Y. N.; Lee, J. Y.; Wang, Daniel. I. C. J. Phys. Chem. C.2008, 112, 5463-5470. Yung, Y.; Luo, Z.; Teo, C.S.; Tan, Y. N.*; Xie, J.* Chem. comm., 2013, 49, 9740-9742. Yu, Y.; Li, J.; Chen, T.; Tan, Y. N.*; Xie, J.* J. Phys. Chem. C. 2015, 119, 10910–10918 Yu, Y; New, S. Y.; Xie, J.; Su, X.*; Tan, Y. N.* Chem. comm., 2014, 50, 13805-13808. Geng, J.; Goh, Walter L.P.; Zhang, C.; Lane, David.; Liu, B.; Ghadessy, Farid J*.; Tan, Y. N.* J. Mater. Chem. B. 2015,3, 5933-5937 Tan, Y. N.; Lai, A.; Su, X. Sci. Adv. Mater, 2014, 6 (7), 1460-1466. Seow N.; Tan, Y. N.*; Su, X.; Lanry Yung*, Scientific Report, 2015, 5:18293. doi: 10.1038/srep18293. Tan, Y. N.; Lee, K. H.; Su, X. RCS Advances, 2013, 3, 21604-21612. Tan, Y. N.; Lee, K. H.; Su, X. Anal. Chem. 2011, 83 (11), 4251–4257. Tan, Y. N.; Su, X.; Zhu, Y.; Lee, J. Y. ACS Nano 2010, 4, 5101–5110. Tan, Y. N.; Su, X.; Liu, Edison T.; Thomsen, J. S. Anal. Chem. 2010, 82, 2759-2765

Identification of the pollution source in steel plant

Kimitsu Works is among the biggest steel mills in the world with several big blast furnaces and other steelmaking equipments which is located near the sea. There are three high chimneys in the mill which produce plume pollution and there are a big coal yard and many dusty roofs which produce dust pollution when the sea wind brings the dust up. Unfortunately, the downtown is just located at the downwind direction about 4km away. To reduce the pollution to the downtown, the administrator of Kimitsu works wants to identify the main sources of the pollution then to adopt some methods such as fixing new dust filter on the top of the chimneys or spraying water to the locations where main dust pollution are produced. Some monitoring instruments which are placed somewhere not far from the pollution sources in the downwind direction is used to measure the concentrate of the plume and dust. During three very busy days, we set up some mathematical models for this problem, obtained some initial results and made clear what future work should be done

Search for D∗(2007)0→μ+μ−D^{*}(2007)^0\to\mu^+\mu^- in B−→π−μ+μ−B^-\to\pi^-\mu^+\mu^- decays

The very rare $D^{*}(2007)^0\to\mu^+\mu^-$ decay is searched for by analysing $B^-\to\pi^-\mu^+\mu^-$ decays. The analysis uses a sample of beauty mesons produced in proton-proton collisions collected with the LHCb detector between 2011 and 2018, corresponding to an integrated luminosity of 9 fb$^{-1}$. The signal signature corresponds to simultaneous peaks in the $\mu^+\mu^-$ and $\pi^-\mu^+\mu^-$ invariant masses. No evidence for an excess of events over background is observed and an upper limit is set on the branching fraction of the decay at ${\cal B}(D^{*}(2007)^0\to\mu^+\mu^-) < 2.6\times 10^{-8}$ at $90\%$ confidence level. This is the first limit on the branching fraction of $D^{*}(2007)^0\to\mu^+\mu^-$ decays and the most stringent limit on $D^{*}(2007)^0$ decays to leptonic final states. The analysis is the first search for a rare charm-meson decay exploiting production via beauty decays.Comment: All figures and tables, along with machine-readable versions and any supplementary material and additional information, are available at https://cern.ch/lhcbproject/Publications/p/LHCb-PAPER-2023-004.html (LHCb public pages