T. Lindén

Extended research on interactive public displays deployed in a city center reveals differences between the public's stated information needs and their actual information behavior and highlights effects that an artificial environment cannot duplicate.

We present the design, implementation, deployment and evaluation of novel urban computing infrastructure called ‘UBI-hotspot’. It is effectively a large interactive public display embedded with other computing resources. We have deployed a network of UBI-hotspots around downtown Oulu, Finland, to establish a public laboratory for conducting experimental ubiquitous computing research in authentic urban setting with diverse real users and with sufficient scale and time span. We focus on the first version of the UBI-hotspot which offers a wide range of services via different interaction modalities. We analyze the usage and user acceptance of the UBI-hotspots from qualitative and quantitative data collected over a period of eight months. Our first observations show that this type of infrastructure may be a useful addition to the urban space.

The NA52 experiment searches for long-lived massive strange quark matter particles, so-called ${\mathit{s}\mathit{t}\mathit{r}\mathit{a}\mathit{n}\mathit{g}\mathit{e}\mathit{l}\mathit{e}\mathit{t}\mathit{s},\phantom{\rule{0ex}{0ex}}\mathrm{p}\mathrm{r}\mathrm{o}\mathrm{d}\mathrm{u}\mathrm{c}\mathrm{e}\mathrm{d}\phantom{\rule{0ex}{0ex}}\mathrm{i}\mathrm{n}\phantom{\rule{0ex}{0ex}}\mathrm{P}\mathrm{b}\ensuremath{-}\mathrm{P}\mathrm{b}\phantom{\rule{0ex}{0ex}}\mathrm{c}\mathrm{o}\mathrm{l}\mathrm{l}\mathrm{i}\mathrm{s}\mathrm{i}\mathrm{o}\mathrm{n}\mathrm{s}\phantom{\rule{0ex}{0ex}}\mathrm{a}\mathrm{t}\phantom{\rule{0ex}{0ex}}\mathrm{a}\phantom{\rule{0ex}{0ex}}\mathrm{b}\mathrm{e}\mathrm{a}\mathrm{m}\phantom{\rule{0ex}{0ex}}\mathrm{m}\mathrm{o}\mathrm{m}\mathrm{e}\mathrm{n}\mathrm{t}\mathrm{u}\mathrm{m}\phantom{\rule{0ex}{0ex}}\mathrm{o}\mathrm{f}\phantom{\rule{0ex}{0ex}}{p}_{\mathrm{lab}}\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}158\mathrm{A}\mathrm{}\mathrm{GeV}\mathrm{/}\mathit{c}.\phantom{\rule{0ex}{0ex}}\mathrm{U}\mathrm{p}\mathrm{p}\mathrm{e}\mathrm{r}\phantom{\rule{0ex}{0ex}}\mathrm{l}\mathrm{i}\mathrm{m}\mathrm{i}\mathrm{t}\mathrm{s}\phantom{\rule{0ex}{0ex}}\mathrm{f}\mathrm{o}\mathrm{r}\phantom{\rule{0ex}{0ex}}\mathrm{t}\mathrm{h}\mathrm{e}\phantom{\rule{0ex}{0ex}}\mathrm{p}\mathrm{r}\mathrm{o}\mathrm{d}\mathrm{u}\mathrm{c}\mathrm{t}\mathrm{i}\mathrm{o}\mathrm{n}\phantom{\rule{0ex}{0ex}}\mathrm{o}\mathrm{f}\phantom{\rule{0ex}{0ex}}\mathrm{s}\mathrm{t}\mathrm{r}\mathrm{a}\mathrm{n}\mathrm{g}\mathrm{e}\mathrm{l}\mathrm{e}\mathrm{t}\mathrm{s}\phantom{\rule{0ex}{0ex}}\mathrm{a}\mathrm{t}\phantom{\rule{0ex}{0ex}}\mathrm{z}\mathrm{e}\mathrm{r}\mathrm{o}\phantom{\rule{0ex}{0ex}}\mathrm{d}\mathrm{e}\mathrm{g}\mathrm{r}\mathrm{e}\mathrm{e}\phantom{\rule{0ex}{0ex}}\mathrm{p}\mathrm{r}\mathrm{o}\mathrm{d}\mathrm{u}\mathrm{c}\mathrm{t}\mathrm{i}\mathrm{o}\mathrm{n}\phantom{\rule{0ex}{0ex}}\mathrm{a}\mathrm{n}\mathrm{g}\mathrm{l}\mathrm{e}\phantom{\rule{0ex}{0ex}}\mathrm{c}\mathrm{o}\mathrm{v}\mathrm{e}\mathrm{r}\mathrm{i}\mathrm{n}\mathrm{g}\phantom{\rule{0ex}{0ex}}\mathrm{a}\phantom{\rule{0ex}{0ex}}\mathrm{m}\mathrm{a}\mathrm{s}\mathrm{s}\phantom{\rule{0ex}{0ex}}\mathrm{t}\mathrm{o}\phantom{\rule{0ex}{0ex}}\mathrm{c}\mathrm{h}\mathrm{a}\mathrm{r}\mathrm{g}\mathrm{e}\phantom{\rule{0ex}{0ex}}\mathrm{r}\mathrm{a}\mathrm{t}\mathrm{i}\mathrm{o}\phantom{\rule{0ex}{0ex}}\mathrm{u}\mathrm{p}\phantom{\rule{0ex}{0ex}}\mathrm{t}\mathrm{o}\phantom{\rule{0ex}{0ex}}120\mathrm{GeV}\mathrm{/}\mathit{c}}^{2}$ and lifetimes ${t}_{\mathrm{lab}}\ensuremath{\gtrsim}1.2$ \ensuremath{\mu}s are given. The data presented here were taken during the 1994 lead beam running period at CERN.

The NA52 experiment measured particle and antiparticle yields at 0° production angle over a wide range in rapidity in lead-lead (Pb-Pb) collisions at 158 A GeV/c with a minimum bias trigger. Besides (106) antiprotons () and (103) antideuterons () a total of five antihelium-3 () were found. The resulting invariant differential production cross sections at pt≃0 GeV/c turn out to be E (d3σ)/(dp3) = (2.5 ± 1.8) × 10-7 bc3 GeV-2 at a rapidity of y = 3.4 in the laboratory system and (5.9 ± 3.4) × 10-8 bc3 GeV-2 at y = 4.0. The results are discussed in the framework of a simple coalescence model.

In this paper we present a web-based framework for spatiotemporal screen real estate management of interactive public displays. The framework facilitates dynamic partitioning of the screen real estate into virtual screens assigned for multiple concurrent web applications. The framework is utilized in the implementation of so-called UBI-hotspot, which provides various information services via different interaction modalities including mobile. The framework facilitates seamless integration of third party web applications residing anywhere in the public Internet into the UBI-hotspot, thus catering for a scalable and open architecture. We report the deployment of a network of indoor and outdoor UBI-hotspots at downtown Oulu, Finland. The quantitative data on the usage of the UBI-hotspots implicitly speaks in favor of the practical applicability of the framework.

This white paper presents the current status of the R&D for Analysis Facilities (AFs) and attempts to summarize the views on the future direction of these facilities. These views have been collected through the High Energy Physics (HEP) Software Foundation's (HSF) Analysis Facilities forum, established in March 2022, the Analysis Ecosystems II workshop, that took place in May 2022, and the WLCG/HSF pre-CHEP workshop, that took place in May 2023. The paper attempts to cover all the aspects of an analysis facility.

We report on baryon and antibaryon as well as K+ and K− production cross sections measured in lead-lead collisions at 158GeV/c per nucleon. The presented data were taken at zero degree production angle with a minimum bias trigger. The measurements covered a wide range of rapidity 1.4<y<6.0. Using a simple thermodynamical and a coalescence model the temperature and the chemical potential of the particle source as well as the freeze-out radius of baryons and antibaryons have been deduced.

Considering resonant three-wave interaction, the authors have derived the coupling coefficients for a cold plasma with sharp boundaries. New terms due to the presence of surface charges, are deduced.

A measurement of the Higgs boson Yukawa coupling to the top quark is presented using proton-proton collision data at $\sqrt{s} =$ 13 TeV, corresponding to an integrated luminosity of 137 fb$^{-1}$, recorded with the CMS detector. The coupling strength with respect to the standard model value, $Y_\mathrm{t}$, is determined from kinematic distributions in $\mathrm{t\bar{t}}$ final states containing ee, $μμ$, or e$μ$ pairs. Variations of the Yukawa coupling strength lead to modified distributions for $\mathrm{t\bar{t}}$ production. In particular, the distributions of the mass of the $\mathrm{t\bar{t}}$ system and the rapidity difference of the top quark and antiquark are sensitive to the value of $Y_\mathrm{t}$. The measurement yields a best fit value of $Y_\mathrm{t} =$ 1.16 $^{+0.24}_{-0.35}$, bounding $Y_\mathrm{t}$ $\lt$ 1.54 at a 95% confidence level.

We searched for long-lived strange quark matter particles, so-called strangelets, and studied particle and antiparticle production in Pb + Pb collisions at 158 GeV/c per nucleon at zero degree production angle. We give upper limits for the production of strangelets covering a mass to charge ratio up to 120 GeV/c2 and lifetimes tlab > 1.2μs and plot invariant differential production cross sections as a function of rapidity for a variety of particles.

We report a novel deployment of so-called UBI-hotspots in a city center to establish an ecosystem infrastructure for conducting diverse urban computing research and business in authentic urban setting. We focus on the value network of the hotspots where the commercial use of the hotspots generates revenue for covering their operational expenses. The value network has been validated by a 12-month long operation, during which the hotspots and their services have been available to the general public on 24/7 basis.

Public displays are becoming a common sight in the urban landscape and they are increasingly being equipped with interaction components such as touch screens. In addition, the Web and its set of enabling technologies are attractive for realizing applications for public displays. We argue that to develop multi-application public displays, then services generally need to be easy to develop, robust, and be easy to deploy and maintain. In this position paper we present a virtual machine-based Web application platform, for decentralized deployment of interactive services on heterogeneous public displays, which satisfies the aforementioned requirements. We also report on some usage experiences of utilizing the platform in a network of large public displays, which we have deployed in a mid-size city.

The challenge of providing a resilient and scalable computational and data management solution for massive scale research environments requires continuous exploration of new technologies and techniques. In this project the aim has been to design a scalable and resilient infrastructure for CERN HEP data analysis. The infrastructure is based on OpenStack components for structuring a private Cloud with the Gluster File System. We integrate the state-of-the-art Cloud technologies with the traditional Grid middleware infrastructure. Our test results show that the adopted approach provides a scalable and resilient solution for managing resources without compromising on performance and high availability.

We investigate antinuclei production in Pb + Pb interactions at 158 GeV/c per nucleon at zero degree production angle. We quote invariant differential production cross sections for antiprotons and antideuterons. The corresponding antideuteron to antiproton ratio at midrapidity is 4.2 · 10−4. One antihelium-3 nucleus was observed. The results are discussed in the framework of a simple coalescence model.

During summer 2006 a fraction of the CMS silicon strip tracker was operated in a comprehensive slice test called the Magnet Test and Cosmic Challenge (MTCC). At the MTCC, cosmic rays detected in the muon chambers were used to trigger the readout of all CMS sub-detectors in the general data acquisition system and in the presence of the 4 T magnetic field produced by the CMS superconducting solenoid. This document describes the operation of the Tracker hardware and software prior, during and after data taking. The performance of the detector as resulting from the MTCC data analysis is also presented.

We provide an experience report of the deployment and maintenance of urban computing infrastructure called UBI-hotspot. It is effectively a large interactive public display embedded with other computing resources such as access points of different wireless networks. We have installed a network of 12 UBI-hotspots in key indoor and outdoor locations around downtown Oulu, Finland. We describe the remote monitoring and management tools we have adopted for the maintenance of the UBI-hotspots. We conclude with a discussion on our lessons learned which should be valuable for other researchers planning similar deployments in public urban spaces.

The CMS experiment expects to manage several Pbytes of data each year during the LHC programme, distributing them over many computing sites around the world and enabling data access at those centers for analysis. CMS has identified the distributed sites as the primary location for physics analysis to support a wide community with thousands potential users. This represents an unprecedented experimental challenge in terms of the scale of distributed computing resources and number of user. An overview of the computing architecture, the software tools and the distributed infrastructure is reported. Summaries of the experience in establishing efficient and scalable operations to get prepared for CMS distributed analysis are presented, followed by the user experience in their current analysis activities.

This paper reports on the charged pion production yields measured by the SPY/NA56 experiment for 450 GeV/c proton interactions on beryllium targets. The present data cover a secondary momentum range from 7 GeV/c to 135 GeV/c in the forward direction. An experimental accuracy ranging from 5 to 10%, depending on the beam momentum, has been achieved, limited mainly by the knowledge of the beam acceptance. These results will be relevant in the calculation of neutrino fluxes in present and future neutrino beams.

This paper reports on the charged K/π production ratios and on the shape of the pT distributions of π fluxes measured by the SPY/NA56 experiment for 450 GeV/c proton interactions on beryllium targets. The present data cover a secondary momentum range from 7 GeV/c to 135 GeV/c in the forward direction and with pT values up to 600 MeV/c. An experimental accuracy of about 3% has been achieved. These results will reduce the uncertainty on the estimation of the νe component of neutrino beams.

We investigate the production mechanisms of p, d, t, 3He, 4He, 6Li, , and in Pb+Pb collisions at 158 A GeV measured near zero transverse momentum with the NA52 experiment at the CERN SPS. We find evidence that nuclei and antinuclei in Pb+Pb collisions are mainly produced via the coalescence mechanism out of a thermalized source of hadrons, at a time close to the thermal freeze-out of hadrons corresponding to a temperature of ~120 MeV.

A search for exclusive two-photon production via photon exchange in proton-proton collisions, pp $\to$ p$γγ$p with intact protons, is presented. The data correspond to an integrated luminosity of 9.4 fb$^{-1}$ collected in 2016 using the CMS and TOTEM detectors at a center-of-mass energy of 13 TeV at the LHC. Events are selected with a diphoton invariant mass above 350 GeV and with both protons intact in the final state, to reduce backgrounds from strong interactions. The events of interest are those where the invariant mass and rapidity calculated from the momentum losses of the forward-moving protons matches the mass and rapidity of the central, two-photon system. No events are found that satisfy this condition. Interpreting this result in an effective dimension-8 extension of the standard model, the first limits are set on the two anomalous four-photon coupling parameters. If the other parameter is constrained to its standard model value, the limits at 95% CL are $\lvertζ_1\rvert$ $\lt$ 2.9 $\times$ 10$^{-13}$ GeV$^{-4}$ and $\lvertζ_2\rvert$ $\lt$ 6.0 $\times$ 10$^{-13}$ GeV$^{-4}$.

ARC and gLite are two of the leading production-ready Grid middleware solutions being used by thousands of researchers every day. Even though the middlewares leverage the same technologies, there are substantial architectural and implementation divergences. Today, users face difficulties trying to cross the boundaries of the two systems. The gLite clients have so far not been capable of accessing ARC resources and vice versa. This paper is a follow up on an earlier proposal on how to enable interoperability between these two middlewares. Further, the paper presents a thorough walkthrough of the protocols and steps involved in the submission of a job in grids built up of the two different middlewares.

Cloud computing improves utilization and flexibility in allocating computing resources while reducing the infrastructural costs. However, in many cases cloud technology is still proprietary and tainted by security issues rooted in the multi-user and hybrid cloud environment. A lack of secure connectivity in a hybrid cloud environment hinders the adaptation of clouds by scientific communities that require scaling-out of the local infrastructure using publicly available resources for large-scale experiments. In this article, we present a case study of the DII-HEP secure cloud infrastructure and propose an approach to securely scale-out a private cloud deployment to public clouds in order to support hybrid cloud scenarios. A challenge in such scenarios is that cloud vendors may offer varying and possibly incompatible ways to isolate and interconnect virtual machines located in different cloud networks. Our approach is tenant driven in the sense that the tenant provides its connectivity mechanism. We provide a qualitative and quantitative analysis of a number of alternatives to solve this problem. We have chosen one of the standardized alternatives, Host Identity Protocol, for further experimentation in a production system because it supports legacy applications in a topologically-independent and secure way.

We present a system for managing the screen real estate of interactive public displays with declarative XML-based descriptions of virtual screens and a finite state machine. The proposed approach includes an algorithm for transforming the declarative virtual screens into a sequence of steps required for transiting between layout states. The system is utilized in realizing an interaction model for a network of public displays in a city center. Our practical experiences show how separating layout description from application logic allows rapid configuration of the interaction model.

In March 2007 the assembly of the Silicon Strip Tracker was completed at the Tracker Integration Facility at CERN. Nearly 15% of the detector was instrumented using cables, fiber optics, power supplies, and electronics intended for the operation at the LHC. A local chiller was used to circulate the coolant for low temperature operation. In order to understand the efficiency and alignment of the strip tracker modules, a cosmic ray trigger was implemented. From March through July 4.5 million triggers were recorded. This period, referred to as the Sector Test, provided practical experience with the operation of the Tracker, especially safety, data acquisition, power, and cooling systems. This paper describes the performance of the strip system during the Sector Test, which consisted of five distinct periods defined by the coolant temperature. Significant emphasis is placed on comparisons between the data and results from Monte Carlo studies.

The results of the CMS tracker alignment analysis are presented using the data from cosmic tracks, optical survey information, and the laser alignment system at the Tracker Integration Facility at CERN. During several months of operation in the spring and summer of 2007, about five million cosmic track events were collected with a partially active CMS Tracker. This allowed us to perform first alignment of the active silicon modules with the cosmic tracks using three different statistical approaches; validate the survey and laser alignment system performance; and test the stability of Tracker structures under various stresses and temperatures ranging from +15 °C to −15 °C. Comparison with simulation shows that the achieved alignment precision in the barrel part of the tracker leads to residual distributions similar to those obtained with a random misalignment of 50 (80) μm RMS in the outer (inner) part of the barrel.

We present new results on the centrality and rapidity dependence and on azimuthal anisotropies of particle production in Pb+Pb collisions at 158 GeV per nucleon.

We present new results of the CERN experiment NA52 on the centrality dependence of π±, K±, p, d, and production yields near zero transverse momentum and at several rapidities, from 64% to 4% of the total Pb + Pb cross section. Baryon yields increase nearly linearly and K± yields faster than linearly with the number of participating nucleons Np. The antibaryon yields increase less than linearly with Np, indicating absorption. The centrality and rapidity dependence of the π−/π+ ratio indicates Coulomb interaction of the pions with the projectile spectator protons. Within the framework of a coalescence model the radius of the particle source has been estimated from the ratios d/p2 and /2. The source radii are similar for matter and antimatter and are found to increase with ∼ Np0.30−0.36.

Inelastic nuclear collisions of hadrons incident on silicon sensors can generate secondary highly ionising particles (HIPs) and deposit as much energy within the sensor bulk as several hundred minimum ionising particles. The large signals generated by these ‘HIP events’ can momentarily saturate the APV25 front-end readout chip for the silicon strip tracker (SST) sub-detector of the compact muon solenoid (CMS) experiment, resulting in deadtime in the detector readout system. This paper presents studies of this phenomenon through simulation, laboratory measurements and dedicated beam tests. A proposed change to a front-end component to reduce the APV25 sensitivity to HIP events is also examined. The results are used to infer the expected effect on the performance of the CMS SST at the future large hadron collider. The induced inefficiencies are at the percent level and will have a negligible effect on the physics performance of the SST.

The Compact Muon Solenoid (CMS) is one of the general purpose experiments at the CERN Large Hadron Collider (LHC). CMS computing relies on different grid infrastructures to provide computational and storage resources. The major grid middleware stacks used for CMS computing are gLite, Open Science Grid (OSG) and ARC (Advanced Resource Connector). Helsinki Institute of Physics (HIP) hosts one of the Tier-2 centers for CMS computing. CMS Tier-2 centers operate software systems for data transfers (PhEDEx), Monte Carlo production (ProdAgent) and data analysis (CRAB). In order to provide the Tier-2 services for CMS, HIP uses tools and components from both ARC and gLite grid middleware stacks. Interoperation between grid systems is a challenging problem and HIP uses two different solutions to provide the needed services. The first solution is based on gLite-ARC grid level interoperability. This allows to use ARC resources in CMS without modifying the CMS application software. The second solution is based on developing specific ARC plugins in CMS software.

The NA52 experiment searches for long-lived charged strangelets in 158 A GeV c-1 Pb + Pb collisions at CERN SPS. The experiment is able to identify single particles coming from the collisions at pt = 0. We collected 1013 Pb + Pb interactions looking for negatively charged strangelets and 3 × 1011 Pb + Pb interactions for positively charged ones. No evidence for the production of strangelets has been observed. We present here resulting experimental differential and total upper production limits.

Nuclear matter is expected to undergo a phase transition to quark matter in ultrarelativistic heavy-ion collisions, possibly showing up as a discontinuity in the impact parameter dependence of relevant observables. Following this expectation, we have investigated the impact parameter dependence of the invariant yields of K±, p, d, and in the range ~ 2 - 12 fm in fixed-target Pb+Pb collisions at 158 GeV/nucleon incident energy at the CERN SPS. The particles have been measured near zero transverse momentum and in the rapidity range y = 3.1 - 4.4. In addition, the centrality dependence of the baryon chemical potential, the effective temperature and the size of the particle emitting source at freeze-out were studied. No dramatic change in the distribution of any of these variables is observed as a function of the impact parameter. The same is found for the particle yields, with the exception of the yield of charged kaons per number of nucleons participating in the collision (Np), where there is an indication of a threshold behaviour at Np~80.

Good geometrical calibration is essential in the use of high resolution detectors. The individual sensors in the detector have to be calibrated with an accuracy better than the intrinsic resolution, which typically is of the order of 10 um. We present an effective method to perform fine calibration of sensor positions in a detector assembly consisting of a large number of pixel and strip sensors. Up to six geometric parameters, three for location and three for orientation, can be computed for each sensor on a basis of particle trajectories traversing the detector system. The performance of the method is demonstrated with both simulated tracks and tracks reconstructed from experimental data. We also present a brief review of other alignment methods reported in the literature.

The NA52 experiment at CERN has investigated lead-lead collisions at 158 A GeV/c and searched for long-lived strange quark matter droplets, so-called strangelets, with a unique signature of a high mass-to-charge ratio. This ratio was measured in a focusing spectrometer equipped with a time-of-flight system. A total of 3×1011 Pb + Pb interactions at positive and 1013 at negative spectrometer polarities have been recorded. No strangelet has been observed, which sets experimental upper limits (90% CL) for the strangelet production at 3×10-9 per interaction for positively charged and at 2×10-10 per interaction for negatively charged strangelets.

The NA52 collaboration searches for a discontinuous behaviour of charged kaons produced in Pb+Pb collisions at 158 A GeV as a function of the impact parameter, which could reveal a hadron to quark-gluon plasma (QGP) phase transition. The K+ yield is found to grow proportional to the number of participating ('wounded') nucleons N, above N=100. Previous NA52 data agree with the above finding and show a discontinuous behaviour in the kaon centrality dependence near N=100, marking the onset of strangeness enhancement -over e.g. p+A data at the same \sqrt{s}- in a chemically equilibrated phase.

A search for long-lived particles (LLPs) produced in association with a Z boson is presented. The study is performed using data from proton-proton collisions with a center-of-mass energy of 13 TeV recorded by the CMS experiment during 2016-2018, corresponding to an integrated luminosity of 117 fb$^{-1}$. The LLPs are assumed to decay to a pair of standard model quarks that are identified as displaced jets within the CMS tracker system. Triggers and selections based on Z boson decays to electron or muon pairs improve the sensitivity to light LLPs (down to 15 GeV). This search provides sensitivity to beyond the standard model scenarios which predict LLPs produced in association with a Z boson. In particular, the results are interpreted in the context of exotic decays of the Higgs boson to a pair of scalar LLPs (H $\to$ SS). The Higgs boson decay branching fraction is constrained to values less than 6% for proper decay lengths of 10-100 mm and for LLP masses between 40 and 55 GeV. In the case of low-mass ($\approx$15 GeV) scalar particles that subsequently decay to a pair of b quarks, the search is sensitive to branching fractions $\mathcal{B}$(H $\to$ SS) $\lt$ 20% for proper decay lengths of 10-50 mm. The use of associated production with a Z boson increases the sensitivity to low-mass LLPs of this analysis with respect to gluon fusion searches. In the case of 15 GeV scalar LLPs, the improvement corresponds to a factor of 2 at a proper decay length of 30 mm.

A measurement of inclusive four-jet production in proton-proton collisions at a center-of-mass energy of 13\TeV is presented. The transverse momenta of jets within $\lvert\eta\rvert \lt$ 4.7 reach down to 35, 30, 25, and 20 GeV for the first-, second-, third-, and fourth-leading jet, respectively. Differential cross sections are measured as functions of the jet transverse momentum, jet pseudorapidity, and several other observables that describe the angular correlations between the jets. The measured distributions show sensitivity to different aspects of the underlying event, parton shower, and matrix element calculations. In particular, the interplay between angular correlations caused by parton shower and double-parton scattering contributions is shown to be important. The double-parton scattering contribution is extracted by means of a template fit to the data, using distributions for single-parton scattering obtained from Monte Carlo event generators and a double-parton scattering distribution constructed from inclusive single-jet events in data. The effective double-parton scattering cross section is calculated and discussed in view of previous measurements and of its dependence on the models used to describe the single-parton scattering background.

Besides the dedicated search for strangelets NA52 measures light (anti)particle and (anti)nuclei production over a wide range of rapidity. Compared to previous runs the statistics has been increased in the 1998 run by more than one order of magnitude for negatively charged objects at different spectrometer rigidities. Together with previous data taking at a rigidity of −20 GeV/c we obtained $$10^6 \bar p, 10^3 \bar d$$ and two $$\overline {^3 He} $$ without centrality requirements. We measured nuclei and antinuclei (p, d, $$\bar p,\bar d$$ ) near midrapidity covering an impact parameter range of b ∼ 2–12 fm. Our results strongly indicate that nuclei and antinuclei are mainly produced via the coalescence mechanism. However, the centrality dependence of the antibaryon to baryon ratios shows that antibaryons are diminished due to annihilation and breakup reactions in the hadron dense environment. The volume of the particle source extracted from coalescence models agrees with results from pion interferometry for an expanding source. The chemical and thermal freeze-out of nuclei and antinuclei appear to coincide with each other and with the thermal freeze-out of hadrons.

CMS user analysis jobs are distributed over the grid with the CMS Remote Analysis Builder application (CRAB). According to the CMS computing model the applications should run transparently on the different grid flavours in use. In CRAB this is handled with different plugins that are able to submit to different grids. Recently a CRAB plugin for submitting to the Advanced Resource Connector (ARC) middleware has been developed. The CRAB ARC plugin enables simple and fast job submission with full job status information available. CRAB can be used with a server which manages and monitors the grid jobs on behalf of the user. In the presentation we will report on the CRAB ARC plugin and on the status of integrating it with the CRAB server and compare this with using the gLite ARC interoperability method for job submission.

An OpenStack based private cloud with the Cluster File System has been built and used with both CMS analysis and Monte Carlo simulation jobs in the Datacenter Indirection Infrastructure for Secure High Energy Physics (DII-HEP) project. On the cloud we run the ARC middleware that allows running CMS applications without changes on the job submission side. Our test results indicate that the adopted approach provides a scalable and resilient solution for managing resources without compromising on performance and high availability.

We have searched for strange matter particles, so-called strangelets, in PbPb interactions at plab = 157.7 GeV/c per nucleon. The NA52 apparatus is also ideally suited to measure production yields and rapidity distributions of π±, K±, p, p, d, d, … near 0° production angle. Some preliminary results are shown.

Ubiquitous computing is quickly becoming mainstream technology and one “killer app” in the field is that it makes unprecedented amounts of data available for data mining purposes. Advanced knowledge discovery techniques make it possible to create detailed profiles of individuals by combining and enriching data collected from a variety of different anonymous data sources. Access to this kind of data may itself become a key driving factor of large-scale ubiquitous computing deployment efforts in the future. Here, a proposal for a set of criteria and enabling technologies for creating low-cost, privacy-preserving grassroots-driven ubiquitous computing applications and infrastructures is outlined. Further, it is argued that a empowered community dedicated to the creation of a privacy-preserving ubiquitous computing ecology might act as a strong-enough counter-force against large-scale industrial deployments that intend to capitalize on this emerging, and potentially fertile market. Additionally, some early results from a real-life deployment of a network of public displays, which implements some of these principles, is also presented.

Besides the dedicated search for strangelets NA52 measures light (anti)particle and (anti)nuclei production over a wide range of rapidity. Compared to previous runs the statistics has been increased in the 1998 run by more than one order of magnitude for negatively charged objects at different spectrometer rigidities. At a rigidity of −20 GeV/c we measured 106 p, 103 d and one 3He without any centrality requirements. These preliminary results together with previous measurements near central rapidity are discussed in the framework of a thermodynamical and a coalescence model.

V&V methods for AI software must adapt to the kinds of development cycles that are practical for complex AI applications that evolve over time; yet V&V requires that each project have a well-defined development process that supports V&V activities. In this paper we introduce a four-dimensional meta-level model about software development processes. This model allows a wide range of software development processes that can be tailored to the unique characteristics of different AI projects—while still providing ways to evaluate the development process and to include the controls needed for V&V. The four dimensions of our model are the definition, formalization, operationality, and performance of the software system. Standard software documentation as well as other software products such as prototypes and formal specifications occur as points in this four-dimensional space, and verification and validation can then be modeled as mappings between points in this space. As software developments proceeds through this four-dimensional space there should be enough intermediate software products acting as waypoints so the development process can be verified and the final software product can be validated in relation to its current requirements.

We have searched for strange matter particles, so‐called strangelets, in Pb‐Pb interactions at plab=157.7 GeV/c per nucleon. The NA52 apparatus is also ideally suited to measure production yields and rapidity distribution of π±, K±, p, p̄, d, d̄, ... near 00 production angle. Some preliminary results are shown.

The impact parameter dependence of π±, K±, p, p, d and d yields produced in fixed target lead+lead collisions at 158 A GeV incident energy is presented. The particle yields are measured near zero transverse momentum and in the forward rapidity region.

We have built a hybrid Grid/Cloud cluster that allows CMS Grid users to submit jobs in a familiar manner.This cluster functions within the CMS production system in a basic form and we are now adding the more advanced features.In this paper we are presenting the results of using the EMI Argus and EES to instantiate new virtual machines within the OpenStack Cloud.The Argus service is used to render the authorization decisions based on X.509 credentials and EES interacts with the OpenStack Cloud infrastructure.

The approach of using a conventional neural network as well as one utilizing the O-algorithm are compared in an application of particle tracking. In the latter case we control the confidence level of the results, which is a major advantage when the network is implemented in hardware.

Tier-2 computing sites in the Worldwide Large Hadron Collider Computing Grid (WLCG) host CPU-resources (Compute Element, CE) and storage resources (Storage Element, SE). The vast amount of data that needs to processed from the Large Hadron Collider (LHC) experiments requires good and efficient use of the available resources. Having a good CPU efficiency for the end users analysis jobs requires that the performance of the storage system is able to scale with I/O requests from hundreds or even thousands of simultaneous jobs.

Kring och inom skolans fors hela tiden en debatt om betygens vara eller icke vara, om betygens utformning och vad som ar nodvandigt for en elev att pavisa kunskap om for att fa ett visst betyg. Ave ...

Charge-dependent anisotropy Fourier coefficients ($v_n$) of particle azimuthal distributions are measured in pPb and PbPb collisions at $ \sqrt{\smash[b]{s_{_{\mathrm{NN}}}}} = $ 5.02 TeV with the CMS detector at the LHC. The normalized difference in the second-order anisotropy coefficients ($v_2$) between positively and negatively charged particles is found to depend linearly on the observed event charge asymmetry with comparable slopes for both pPb and PbPb collisions over a wide range of charged particle multiplicity. In PbPb, the third-order anisotropy coefficient, $v_3$, shows a similar linear dependence with the same slope as seen for $v_2$. The observed similarities between the $v_2$ slopes for pPb and PbPb, as well as the similar slopes for $v_2$ and $v_3$ in PbPb, are compatible with expectations based on local charge conservation in the decay of clusters or resonances, and constitute a challenge to the hypothesis that the observed charge asymmetry dependence of $v_2$ in heavy ion collisions arises from a chiral magnetic wave.

We are presenting new results on K± and π± production in minimum bias lead-lead collisions at 158 A GeV/c. The measurements were performed at zero degree production angle and for a wide rapidity range. The analysis method used the full particle identification capabilities (time of flight, Cerenkov counters and hadronic calorimeter) of the spectrometer. We show K/π and π−/π+ ratios as a function of rapidity, as well as invariant particle production cross sections. As a particularity we observe near projectile rapidity an enhancement in the number of π− with respect to π+.