279 research outputs found

    Possible scenarios for soft and semi-hard components structure in central hadron-hadron collisions in the TeV region

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    Possible scenarios in hh collisions in the TeV regions are discussed in full phase space. It is shown that at such high energies one should expect strong KNO scaling violation and a ln(s) increase of the average charged multiplicity of the semi-hard component, resulting in a huge mini-jet production.Comment: 20 pages, 9 PS figures included, LaTeX2e with AMSmath, epsfi

    Scenarios for multiplicity distributions in pp collisions in the TeV energy region

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    Possible scenarios based on available experimental data and phenomenological knowledge of the GeV energy region are extended to the TeV energy region in the framework of the weighted superposition mechanism of soft and semi-hard events. KNO scaling violations, forward-backward multiplicity correlations, Hq vs. q oscillations and shoulder structures are discussed.Comment: 10 pages, 10 figures, talk given at "Focus on Multiplicity" (Bari, Italy, June 2004

    The ALTCRISS Project On Board the International Space Station

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    The Altcriss project aims to perform a long term survey of the radiation environment on board the International Space Station. Measurements are being performed with active and passive devices in different locations and orientations of the Russian segment of the station. The goal is perform a detailed evaluation of the differences in particle fluence and nuclear composition due to different shielding material and attitude of the station. The Sileye-3/Alteino detector is used to identify nuclei up to Iron in the energy range above approximately equal to 60 MeV/n; a number of passive dosimeters (TLDs, CR39) are also placed in the same location of Sileye-3 detector. Polyethylene shielding is periodically interposed in front of the detectors to evaluate the effectiveness of shielding on the nuclear component of the cosmic radiation. The project was submitted to ESA in reply to the AO the Life and Physical Science of 2004 and was begun in December 2005. Dosimeters and data cards are rotated every six months: up to now three launches of dosimeters and data cards have been performed and have been returned with the end expedition 12 and 13

    Questions and Remarks About Clans in Multiparticle Dynamics

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    The fact that several important effects in multiparticle dynamics, on which QCD has not yet satisfactory predictions, have been interpreted in terms of the validity of negative binomial (Pascal) regularity and related clan properties at the level of simpler substructures, raises intriguing questions on clan properties in all classes of collisions, the main one being whether clans are observable objects or merely a mathematical concept. We approach this problem by studying clan masses and rapidity distributions in each substructure for e+e- annihilation and hh collisions, and find that such properties can indeed characterise the different components. These results support the idea that clans could be observable, a challenging problem for future experiments.Comment: 11 pages; 3 figures; latex 2e and amsmat

    The ALTCRISS project on board the International Space Station

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    The Altcriss project aims to perform a long term survey of the radiation environment on board the International Space Station. Measurements are being performed with active and passive devices in different locations and orientations of the Russian segment of the station. The goal is to perform a detailed evaluation of the differences in particle fluence and nuclear composition due to different shielding material and attitude of the station. The Sileye-3/Alteino detector is used to identify nuclei up to Iron in the energy range above 60 MeV/n. Several passive dosimeters (TLDs, CR39) are also placed in the same location of Sileye-3 detector. Polyethylene shielding is periodically interposed in front of the detectors to evaluate the effectiveness of shielding on the nuclear component of the cosmic radiation. The project was submitted to ESA in reply to the AO in the Life and Physical Science of 2004 and data taking began in December 2005. Dosimeters and data cards are rotated every six months: up to now three launches of dosimeters and data cards have been performed and have been returned with the end of expedition 12 and 13.Comment: Accepted for publication on Advances in Space Research http://dx.doi.org/10.1016/j.asr.2007.04.03

    Clan structure analysis and new physics signals in pp collisions at LHC

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    The study of possible new physics signals in global event properties in pp collisions in full phase space and in rapidity intervals accessible at LHC is presented. The main characteristic is the presence of an elbow structure in final charged particle MD's in addition to the shoulder observed at lower c.m. energies.Comment: 9 pages, talk given at Focus on Multiplicity (Bari, Italy, June 2004

    Clan Structure Analysis and Rapidity Gap Probability

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    Clan structure analysis in rapidity intervals is generalized from negative binomial multiplicity distribution to the wide class of compound Poisson distributions. The link of generalized clan structure analysis with correlation functions is also established. These theoretical results are then applied to minimum bias events and evidentiate new interesting features, which can be inspiring and useful in order to discuss data on rapidity gap probability at TEVATRON and HERA.Comment: (14 pages in Plain TeX plus 5 Postscript Figures, all compressed via uufiles) DFTT 28/9

    Charged-Particle Multiplicity in Proton-Proton Collisions

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    This article summarizes and critically reviews measurements of charged-particle multiplicity distributions and pseudorapidity densities in p+p(pbar) collisions between sqrt(s) = 23.6 GeV and sqrt(s) = 1.8 TeV. Related theoretical concepts are briefly introduced. Moments of multiplicity distributions are presented as a function of sqrt(s). Feynman scaling, KNO scaling, as well as the description of multiplicity distributions with a single negative binomial distribution and with combinations of two or more negative binomial distributions are discussed. Moreover, similarities between the energy dependence of charged-particle multiplicities in p+p(pbar) and e+e- collisions are studied. Finally, various predictions for pseudorapidity densities, average multiplicities in full phase space, and multiplicity distributions of charged particles in p+p(pbar) collisions at the LHC energies of sqrt(s) = 7 TeV, 10 TeV, and 14 TeV are summarized and compared.Comment: Invited review for Journal of Physics G -- version 2: version after referee's comment

    A fine-grained silicon detector for high-energy gamma-ray astrophysics

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    We propose a silicon telescope to be placed in a satellite for the search of g-ray sources in the energy range between 25 MeV and 100 GeV. The proposed experiment will have an area of 2500 cm2, an energy resolution ranging from 7% to 8% and an angular resolution from 0.2 and 0.1 degrees between 1 GeV and 10 GeV. The telescope is based on the use of silicon strip detectors. Together with the energy measurement, a calorimeter of this type allows the determination of the particle type and its arrival direction, through the analysis of the spatial and energetic distribution of the electromagnetic shower produced. Detectors based on silicon technology have many advantages for space applications: no gas refilling system or high voltages, no need of photomultipliers (low consumption), short dead time, possibility of selftriggering. The GILDA project has been designed having in mind the weight limitation of 400 kg required by the Resource-01 satellite and it is carried out in the framework of the RIM (Russian Italian Mission) program. The launch is foreseen for the beginning of the next century

    The construction of an idealised urban masculinity among men with concurrent sexual partners in a South African township

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    Background : The perspectives of heterosexual males who have large sexual networks comprising concurrent sexual partners and who engage in high-risk sexual behaviours are scarcely documented. Yet these perspectives are crucial to understanding the high HIV prevalence in South Africa where domestic violence, sexual assault and rape are alarmingly high, suggesting problematic gender dynamics. Objective : To explore the construction of masculinities and men's perceptions of women and their sexual relationships, among men with large sexual networks and concurrent partners. Design : This qualitative study was conducted in conjunction with a larger quantitative survey among men at high risk of HIV, using respondent-driven sampling to recruit participants, where long referral chains allowed us to reach far into social networks. Twenty in-depth, open-ended interviews with South African men who had multiple and concurrent sexual partners were conducted. A latent content analysis was used to explore the characteristics and dynamics of social and sexual relationships. Results : We found dominant masculine ideals characterised by overt economic power and multiple sexual partners. Reasons for large concurrent sexual networks were the perception that women were too empowered, could not be trusted, and lack of control over women. Existing masculine norms encourage concurrent sexual networks, ignoring the high risk of HIV transmission. Biological explanations and determinism further reinforced strong and negative perceptions of women and female sexuality, which helped polarise men's interpretation of gender constructions. Conclusions : Our results highlight the need to address sexuality and gender dynamics among men in growing, informal urban areas where HIV prevalence is strikingly high. Traditional structures that could work as focal entry points should be explored for effective HIV prevention aimed at normative change among hard-to-reach men in high-risk urban and largely informal contexts
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