79 research outputs found

    HL-LHC layout for fixed-target experiments in ALICE based on crystal-assisted beam halo splitting

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    The Large Hadron Collider (LHC) at the European Organization for Nuclear Research (CERN) is the world's largest and most powerful particle accelerator colliding beams of protons and lead ions at energies up to 7 ZTeV, Z is the atomic number. ALICE is one of the detector experiments optimised for heavy-ion collisions. A fixed-target experiment in ALICE is being considered to collide a portion of the beam halo, split using a bent crystal inserted in the transverse hierarchy of the LHC collimation system, with an internal target placed a few meters upstream of the existing detector. This study is carried out as a part of the Physics Beyond Collider effort at CERN. Fixed-target collisions offer many physics opportunities related to hadronic matter and the quark-gluon plasma to extend the research potential of the CERN accelerator complex. Production of physics events depends on the particle flux on target. The machine layout for the fixed-target experiment is developed to provide a flux of particles on the target high enough to exploit the full capabilities of the ALICE detector acquisition system. This paper summarises the fixed-target layout consisting of the crystal assembly, the target and downstream absorbers. We discuss the conceptual integration of these elements within the LHC ring, the impact on ring losses, and expected performance in terms of particle flux on target

    Efficacy and accuracy of maxillary arch expansion with clear aligner treatment

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    The aim of this work was to evaluate the efficacy and accuracy of maxillary arch transverse expansion using the Invisalign® clear aligner system without auxiliaries other than Invisalign attachments. Knowing the accuracy of a movement through a clear aligner system allows the clinician to plan the treatment with greater precision and to achieve the expected result faster. The study group included 28 patients with a mean age of 17 ± 3.2 years. The treatment protocol for all the selected patients included the application of the Invisalign® clear aligner system without auxiliaries, except for the Invisalign® attachments; in no case were tooth extraction or interproximal enamel reduction (IPR) performed. Linear measurements of the expansion were assessed before treatment (T0), at the end of treatment (T1), and on final virtual models by ClinCheck® (TC). A paired t-test was used to compare T0-T1 and T1-TC differences. A paired t-test was applied, and one normality was validated with the Shapiro-Wilks test. If normality was not met, the nonparametric test (Mann-Whitney U test) was applied. The level of significance was set at 5%. Statistically significant differences were found for all measurements at T0-T1. The results showed an average accuracy of efficacy of 70.88%. The differences in predictability between the various vestibular measurements (intercanine, inter-premolar, and intermolar) were not statistically significant, while they were for gingival measurements. The overall accuracy of the expansion treatment was 70%, regardless of tooth type

    Assessment of the prevalence and risk factors of low back pain in operating room health workers: An observational study in Italy

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    Aim: The aim of this study was to assess the prevalence of low back pain (LBP) among healthprofessionals and the possible risk factors. Methods: The study was carried out from April 2018 to October 2018 among all health workers of the Orthopaedic Clinic and the Emergency Department of “Policlinico Umberto I” in Rome. LBP was assessed using the Nordic Questionnaire Musculoskeletal Disorders in the section on lumbar pain. The type of physical activity carried out as prevention was investigated by use of the International Physical Activity Questionnaires. The overall state of health and lifestyle was deter- mined by the Short Form 12-item Health Survey. Job satisfaction and perceived work stress were assessed through the 15-questions of Karasek’s Questionnaire. The intensity of the low back pain was assessed using a Numerical Rating Scale. A univariate analysis was conducted to assess the associations between socio-demographic and working variables. Multiple logistic regression mod- els were used to assess independent correlates of LBP. Results: One hundred thirteen subjects were enrolled, 52 women and 61 men. The annual period- prevalence of lumbar musculoskeletal disorder was found on 79.6% of participants with LBP. Mean value evidence of NRS was 2.66. The highest LBP risk over the 12 months was found in groups with high job demand (OR = 1.18; 95%CI: 1.01 – 1.38), low decision-making opportunities (for decision latitude OR = 0.87; (0-76 – 1.0), and low levels of physical activity (OR = 0.75; 95%CI: 0.64 – 0.89). Conclusion: The working environment is a potential risk factor for the development of LBP and is suitable for prevention programmes. The protective effect of physical activity and work-related stress management indicate room for improvements for the prevention of LBP in these HCWs. Conflicts of interest: None declared

    Assessment of the prevalence and risk factors of low back pain in operating room health workers: An observational study in Italy

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    Aim: The aim of this study was to assess the prevalence of low back pain (LBP) among healthprofessionals and the possible risk factors. Methods: The study was carried out from April 2018 to October 2018 among all health workers of theOrthopaedic Clinic and the Emergency Department of “Policlinico Umberto I” in Rome. LBP wasassessed using the Nordic Questionnaire Musculoskeletal Disorders in the section on lumbar pain.The type of physical activity carried out as prevention was investigated by use of theInternational Physical Activity Questionnaires. The overall state of health and lifestyle wasdeter- mined by the Short Form 12-item Health Survey. Job satisfaction and perceived work stresswere assessed through the 15-questions of Karasek’s Questionnaire. The intensity of the low backpain was assessed using a Numerical Rating Scale. A univariate analysis was conducted to assess theassociations between socio-demographic and working variables. Multiple logistic regression mod- elswere used to assess independent correlates of LBP. Results: One hundred thirteen subjects were enrolled, 52 women and 61 men. The annual period-prevalence of lumbar musculoskeletal disorder was found on 79.6% of participants with LBP.Mean value evidence of NRS was 2.66. The highest LBP risk over the 12 months was found in groupswith high job demand (OR = 1.18; 95%CI: 1.01 – 1.38), low decision-making opportunities (fordecision latitude OR = 0.87; (0-76 – 1.0), and low levels of physical activity (OR = 0.75; 95%CI:0.64 – 0.89). Conclusion: The working environment is a potential risk factor for the development of LBP and issuitable for prevention programmes. The protective effect of physical activity and work-relatedstress management indicate room for improvements for the prevention of LBP in these HCWs. Conflicts of interest: None declared

    Strong reduction of the off-momentum halo in crystal assisted collimation of the SPS beam

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    A study of crystal assisted collimation has been continued at the CERN SPS for different energies of stored beams using 120 GeV/. c and 270 GeV/. c protons and Pb ions with 270 GeV/. c per charge. A bent silicon crystal used as a primary collimator deflected halo particles using channeling and directing them into the tungsten absorber. A strong correlation of the beam losses in the crystal and off-momentum halo intensity measured in the first high dispersion (HD) area downstream was observed. In channeling conditions, the beam loss rate induced by inelastic interactions of particles with nuclei is significantly reduced in comparison with the non-oriented crystal. A maximal reduction of beam losses in the crystal larger than 20 was observed with 270 GeV/. c protons. The off-momentum halo intensity measured in the HD area was also strongly reduced in channeling conditions. The reduction coefficient was larger than 7 for the case of Pb ions. A strong loss reduction was also detected in regions of the SPS ring far from the collimation area. It was shown by simulations that the miscut angle between the crystal surface and its crystallographic planes doubled the beam losses in the aligned crystal.peer-reviewe

    Comparative results on collimation of the SPS beam of protons and Pb ions with bent crystals

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    New experiments on crystal assisted collimation have been carried out at the CERN SPS with stored beams of 120 GeV/. c protons and Pb ions. Bent silicon crystals of 2 mm long with about 170 ÎĽrad bend angle and a small residual torsion were used as primary collimators. In channeling conditions, the beam loss rate induced by inelastic interactions of particles with the crystal nuclei is minimal. The loss reduction was about 6 for protons and about 3 for Pb ions. Lower reduction value for Pb ions can be explained by their considerably larger ionization losses in the crystal. In one of the crystals, the measured fraction of the Pb ion beam halo deflected in channeling conditions was 74%, a value very close to that for protons. The intensity of the off-momentum halo leaking out from the collimation station was measured in the first high dispersion area downstream. The particle population in the shadow of the secondary collimator-absorber was considerably smaller in channeling conditions than for amorphous orientations of the crystal. The corresponding reduction was in the range of 2-5 for both protons and Pb ions.peer-reviewe

    Observation of parametric X-rays produced by 400 GeV/c protons in bent crystals

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    Spectral maxima of parametric X-ray radiation (PXR) produced by 400 GeV/c protons in bent silicon crystals aligned with the beam have been observed in an experiment at the H8 external beam of the CERN SPS. The total yield of PXR photons was about 10-6 per proton. Agreement between calculations and the experimental data shows that the PXR kinematic theory is valid for bent crystals with sufficiently small curvature as used in the experiment. The intensity of PXR emitted from halo protons in a bent crystal used as a primary collimator in a circular accelerator may be considered as a possible tool to control its crystal structure, which is slowly damaged because of irradiation. The intensity distribution of PXR peaks depends on the crystal thickness intersected by the beam, which changes for different orientations of a crystal collimator. This dependence may be used to control crystal collimator alignment by analyzing PXR spectra produced by halo protons.peer-reviewe

    Covid-19 and the role of smoking: the protocol of the multicentric prospective study COSMO-IT (COvid19 and SMOking in ITaly).

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    The emergency caused by Covid-19 pandemic raised interest in studying lifestyles and comorbidities as important determinants of poor Covid-19 prognosis. Data on tobacco smoking, alcohol consumption and obesity are still limited, while no data are available on the role of e-cigarettes and heated tobacco products (HTP). To clarify the role of tobacco smoking and other lifestyle habits on COVID-19 severity and progression, we designed a longitudinal observational study titled COvid19 and SMOking in ITaly (COSMO-IT). About 30 Italian hospitals in North, Centre and South of Italy joined the study. Its main aims are: 1) to quantify the role of tobacco smoking and smoking cessation on the severity and progression of COVID-19 in hospitalized patients; 2) to compare smoking prevalence and severity of the disease in relation to smoking in hospitalized COVID-19 patients versus patients treated at home; 3) to quantify the association between other lifestyle factors, such as e-cigarette and HTP use, alcohol and obesity and the risk of unfavourable COVID-19 outcomes. Socio-demographic, lifestyle and medical history information will be gathered for around 3000 hospitalized and 700-1000 home-isolated, laboratory-confirmed, COVID-19 patients. Given the current absence of a vaccine against SARS-COV-2 and the lack of a specific treatment for -COVID-19, prevention strategies are of extreme importance. This project, designed to highly contribute to the international scientific debate on the role of avoidable lifestyle habits on COVID-19 severity, will provide valuable epidemiological data in order to support important recommendations to prevent COVID-19 incidence, progression and mortality
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