Measurement of transverse spin effects in COMPASS on a polarised proton target

2007/2008After a short introduction to the physics of COMPASS and the description of the spectrometer, the RICH-1 upgrade project is presented within the performed laboratory activities. Also the preliminary results of the performances of the new RICH-1 are illustrated. The focus then moves on the analysis of the data, and taking advantage of the upgraded RICH-1, the Collins and the Sivers asymmetries, extracted from the data collected during the transverse run of 2007, are presented both for unidentified and identified hadrons.XXI Ciclo197

Multichannel Time Synchronization Based on PTP through a High Voltage Isolation Buffer Network Interface for Thick-GEM Detectors

Data logging and complex algorithm implementations acting on multichannel systems with independent devices require the use of time synchronization. In the case of Gas Electron Multipliers (GEM) and Thick-GEM (THGEM) detectors, the biasing potential can be generated at the detector level via DC to DC converters operating at floating voltage. In this case, high voltage isolation buffers may be used to allow communication between the different channels. However, their use add non-negligible delays in the transmission channel, complicating the synchronization. Implementation of a simplified precise time protocol is presented for handling the synchronization on the Field Programmable Gate Array (FPGA) side of a Xilinx SoC Zynq ZC7Z030. The synchronization is done through a high voltage isolated bidirectional network interface built on a custom board attached to a commercial CIAA_ACC carrier. The results of the synchronization are shown through oscilloscope captures measuring the time drift over long periods of time, achieving synchronization in the order of nanoseconds

Multiplicities of charged pions and unidentified charged hadrons from deep-inelastic scattering of muons off an isoscalar target

Multiplicities of charged pions and unidentified hadrons produced in deep-inelastic scattering were measured in bins of the Bjorken scaling variable $x$, the relative virtual-photon energy $y$ and the relative hadron energy $z$. Data were obtained by the COMPASS Collaboration using a 160 GeV muon beam and an isoscalar target ($^6$LiD). They cover the kinematic domain in the photon virtuality $Q^2$ > 1(GeV/c$)^2$, $0.004 < x < 0.4$, $0.2 < z < 0.85$ and $0.1 < y < 0.7$. In addition, a leading-order pQCD analysis was performed using the pion multiplicity results to extract quark fragmentation functions

The Polarised Valence Quark Distribution from semi-inclusive DIS

The semi-inclusive difference asymmetry A^{h^{+}-h^{-}} for hadrons of opposite charge has been measured by the COMPASS experiment at CERN. The data were collected in the years 2002-2004 using a 160 GeV polarised muon beam scattered off a large polarised ^6LiD target and cover the range 0.006 < x < 0.7 and 1 < Q^2 < 100 (GeV/c)^2. In leading order QCD (LO) the asymmetry A_d^{h^{+}-h^{-}} measures the valence quark polarisation and provides an evaluation of the first moment of Delta u_v + Delta d_v which is found to be equal to 0.40 +- 0.07 (stat.) +- 0.05 (syst.) over the measured range of x at Q^2 = 10 (GeV/c)^2. When combined with the first moment of g_1^d previously measured on the same data, this result favours a non-symmetric polarisation of light quarks Delta u-bar = - Delta d-bar at a confidence level of two standard deviations, in contrast to the often assumed symmetric scenario Delta u-bar = Delta d-bar = Delta s-bar = Delta s.Comment: 7 pages, 3 figures, COMPASS, revised: details added, author list update

Lifestyles and socio-cultural factors among children aged 6-8 years from five Italian towns: The MAPEC-LIFE study cohort

Background: Lifestyles profoundly determine the quality of an individual’s health and life since his childhood. Many diseases in adulthood are avoidable if health-risk behaviors are identified and improved at an early stage of life. The aim of the present research was to characterize a cohort of children aged 6–8 years selected in order to perform an epidemiological molecular study (the MAPEC_LIFE study), investigate lifestyles of the children that could have effect on their health status, and assess possible association between lifestyles and socio-cultural factors. Methods: A questionnaire composed of 148 questions was administered in two different seasons to parents of children attending 18 primary schools in five Italian cities (Torino, Brescia, Pisa, Perugia and Lecce) to obtain information regarding the criteria for exclusion from the study, demographic, anthropometric and health information on the children, as well as some aspects on their lifestyles and parental characteristics. The results were analyzed in order to assess the frequency of specific conditions among the different seasons and cities and the association between lifestyles and socio-economic factors. Results: The final cohort was composed of 1,164 children (50.9 boys, 95.4% born in Italy). Frequency of some factors appeared different in terms of the survey season (physical activity in the open air, the ways of cooking certain foods) and among the various cities (parents’ level of education and rate of employment, sport, traffic near the home, type of heating, exposure to passive smoking, ways of cooking certain foods). Exposure to passive smoking and cooking fumes, obesity, residence in areas with heavy traffic, frequency of outdoor play and consumption of barbecued and fried foods were higher among children living in families with low educational and/or occupational level while children doing sports and consuming toasted bread were more frequent in families with high socio-economic level. Conclusions: The socio-economic level seems to affect the lifestyles of children enrolled in the study including those that could cause health effects. Many factors are linked to the geographical area and may depend on environmental, cultural and social aspects of the city of residence

Multiplicities of charged kaons from deep-inelastic muon scattering off an isoscalar target

Precise measurements of charged-kaon multiplicities in deep inelastic scattering were performed. The results are presented in three-dimensional bins of the Bjorken scaling variable x, the relative virtual-photon energy y, and the fraction z of the virtual-photon energy carried by the produced hadron. The data were obtained by the COMPASS Collaboration by scattering 160 GeV muons off an isoscalar 6LiD target. They cover the kinematic domain View the MathML source in the photon virtuality, 0.0045 GeV/c2 in the invariant mass of the hadronic system. The results from the sum of the z -integrated K+ and K 12 multiplicities at high x point to a value of the non-strange quark fragmentation function larger than obtained by the earlier DSS fit

Newest COMPASS results on longitudinal and transverse nucleon spin structure.

The COMPASS experiment at CERN has performed a rich programme in inclusive and semi-inclusive deep inelastic scattering of longitudinally polarised muons off longitudinally, transversely polarised and unpolarised nucleons. The main topic is the investigation of the spin structure of the nucleon in terms of quark and gluons, both through accessing the spin dependent collinear parton distribution functions and studying the transverse momentum dependent TMD PDFs and FFs The newest results on the spin structure function of the proton and the deuteron, on the transversity and Sivers PDFs and the measurements of hadron multiplicities will be shown. Plans for the near future will also be presented. In this proceeding only the results obtained using a muon beam will be reported