Production of Scalar Higgs Bosons Associated with Z0Z^0 Boson at the CERN LHC in the MSSM

We investigate the associated production of a scalar Higgs boson ($h^0$ or $H^0$) with $Z^0$ boson in the minimal supersymmetric extension of the standard model (MSSM) at the CERN Large Hadron Collider (LHC), including the contributions from $b\bar{b}$ annihilation at the tree level and gluon fusion via quark and squark loops. We quantitatively analyze the total cross sections in the mSUGRA scenario. For the production of $h^0$ associated with $Z^0$, we find that in most of the parameter regions, the contributions from initial $b\bar{b}$ and $gg$ are at a level of one percent of the total cross section and therefore almost insignificant. For the production of $H^0$ associated with $Z^0$, the contributions from $b\bar{b}$ channel can be much larger than those from light quark initial states. Especially for large $\tan\beta$, the increment can reach about one order of magnitude. Thus, when considering the associated production of $H^0$ and $Z^0$ at the LHC, the contributions from $b\bar{b}$ annihilation should be taken into account seriously.Comment: 19 pages, 8 figures, RevTeX4; one reference added, minor changes, conclusion unchanged; Journal-ref adde

The super-LHC

We review here the prospects of a long-term upgrade programme for the Large Hadron Collider (LHC), CERN laboratory's new proton-proton collider. The super-LHC, which is currently under evaluation and design, is expected to deliver of the order of ten times the statistics of the LHC. In addition to a non-technical summary of the principal physics arguments for the upgrade, I present a pedagogical introduction to the technological challenges on the accelerator and experimental fronts, and a review of the current status of the planning.Comment: To appear in Contemporary Physic

Characterization and Performance of PADME's Cherenkov-Based Small-Angle Calorimeter

The PADME experiment, at the Laboratori Nazionali di Frascati (LNF), in Italy, will search for invisible decays of the hypothetical dark photon via the process $e^+e^-\rightarrow \gamma A'$, where the $A'$ escapes detection. The dark photon mass range sensitivity in a first phase will be 1 to 24 MeV. We report here on measurement and simulation studies of the performance of the Small-Angle Calorimeter, a component of PADME's detector dedicated to rejecting 2- and 3-gamma backgrounds. The crucial requirement is a timing resolution of less than 200 ps, which is satisfied by the choice of PbF$_2$ crystals and the newly released Hamamatsu R13478UV photomultiplier tubes (PMTs). We find a timing resolution of 81 ps (with double-peak separation resolution of 1.8 ns) and a single-crystal energy resolution of 5.7%/$\sqrt{E}$ with light yield of 2.07 photo-electrons per MeV, using 100 to 400 MeV electrons at the Beam Test Facility of LNF. We also propose the investigation of a two-PMT solution coupled to a single PbF$_2$ crystal for higher-energy applications, which has potentially attractive features.Comment: 12 pages, 19 figures. v2: added section on radiation damage studie

Status and Plans for the Array Control and Data Acquisition System of the Cherenkov Telescope Array

The Cherenkov Telescope Array (CTA) is the next-generation atmospheric Cherenkov gamma-ray observatory. CTA will consist of two installations, one in the northern, and the other in the southern hemisphere, containing tens of telescopes of different sizes. The CTA performance requirements and the inherent complexity associated with the operation, control and monitoring of such a large distributed multi-telescope array leads to new challenges in the field of the gamma-ray astronomy. The ACTL (array control and data acquisition) system will consist of the hardware and software that is necessary to control and monitor the CTA arrays, as well as to time-stamp, read-out, filter and store -at aggregated rates of few GB/s- the scientific data. The ACTL system must be flexible enough to permit the simultaneous automatic operation of multiple sub-arrays of telescopes with a minimum personnel effort on site. One of the challenges of the system is to provide a reliable integration of the control of a large and heterogeneous set of devices. Moreover, the system is required to be ready to adapt the observation schedule, on timescales of a few tens of seconds, to account for changing environmental conditions or to prioritize incoming scientific alerts from time-critical transient phenomena such as gamma ray bursts. This contribution provides a summary of the main design choices and plans for building the ACTL system.Comment: In Proceedings of the 34th International Cosmic Ray Conference (ICRC2015), The Hague, The Netherlands. All CTA contributions at arXiv:1508.0589

IBIS/PICsIT in-flight performances

PICsIT (Pixellated Imaging CaeSium Iodide Telescope) is the high energy detector of the IBIS telescope on-board the INTEGRAL satellite. PICsIT operates in the gamma-ray energy range between 175 keV and 10 MeV, with a typical energy resolution of 10% at 1 MeV, and an angular resolution of 12 arcmin within a \~100 square degree field of view, with the possibility to locate intense point sources in the MeV region at the few arcmin level. PICsIT is based upon a modular array of 4096 independent CsI(Tl) pixels, ~0.70 cm^2 in cross-section and 3 cm thick. In this work, the PICsIT on-board data handling and science operative modes are described. This work presents the in-flight performances in terms of background count spectra, sensitivity limit, and imaging capabilities.Comment: 8 pages, 4 figures. Accepted for publication on A&A, special issue on First Science with INTEGRA

Information needs after stroke: What to include and how to structure it on a website. A qualitative study using focus groups and card sorting

Background: Use of the Internet to obtain health and other information is increasing. Previous studies have identified the specific information needs of people with stroke but not in relation to the Internet. People with aphasia (PwA) may face barriers in accessing the Internet: Navigating websites requires an ability to categorise information and this ability is often impaired in PwA. The website categorisation preferences of people with stroke and with aphasia have not yet been reported. Aims: This study aimed: (a) to determine what information people who have had a stroke would like to see on a website about living with stroke; (b) to determine the most effective means of structuring information on the website so that it is accessible to people with stroke; and c) to identify any differences between people with and without aphasia in terms of preferences for structuring information on the website. Methods & Procedures: Participants were recruited from a hospital's Stroke Database. Focus groups were used to elicit what information participants wanted on a website about living with stroke. The themes raised were depicted on 133 cards. To determine the most effective way of structuring information on the website, and whether there were any differences in preferences between PwA and PwoA, participants used a modified closed card-sorting technique to sort the cards under website categories. Outcomes & Results: A total of 48 people were invited, and 12 (25%) agreed to take part. We ran three focus groups: one with PwA (n = 5) and two with people without aphasia (PwoA) (n = 3, n = 4). Participants wanted more information about stroke causes and effects (particularly emotional issues), roles of local agencies, and returning to previous activities (driving, going out). All participants completed the card-sorting exercise. Few cards (6%) were categorised identically by everyone. Cards relating to local agencies and groups were not consistently categorised together. Cards relating to emotions were segregated. The categorisation preferences for PwA were more fragmented than those for PwoA: 60% of PwA agreed on the categorisation of 51% of the cards, whereas 60% of PwoA agreed on the categorisation of 76% of the cards. Conclusions: Information needs covered all stages of the stroke journey. The card sorting was accessible to everyone, and provided evidence of structuring preferences and of some of the categorisation difficulties faced by PwA. More research is needed on what an accessible website looks like for PwA