41 research outputs found

    The prototype phase of the ENUBET positron tagger

    Get PDF
    Understanding the interaction of neutrinos with the other particles of the Standard Model is a fundamental activity in particle physics. The uncertainties on the initial neutrino flux limit the sensitivity on the neutrino cross section measurement in the GeV range to a precision of 10-20%. The scientific goal of the ENUBET project is to improve this sensitivity up to 1% by developing an active decay tunnel, as opposed to traditional neutrino beams, which have a passive decay region. By tagging the positrons emitted in the Ke3 decay (K+ -> \u3c00 + e+ + \u3bde) it is possible to infer the initial neutrino flux. If the tunnel is short enough (about 50 m) the Ke3 decay is the only source of neutrinos. Shashlik calorimeters are suitable to instrument such a tunnel, because they are cost effective, have a good geometrical adaptability and their energy resolution can be tuned with the proper absorbing/scintillator tiles thickness and fiber frequency. To separate the positrons from the pion background these calorimeters are longitudinally segmented with a compact readout based on Silicon PhotoMultipliers embedded in the bulk of the calorimeter itself. This thesis describes the prototyping activity of the ENUBET Collaboration for the positron tagger and the tests performed at the CERN PS-T9 beamline from July 2016 to October 2017. The details of each prototype design and the results in terms of linearity and energy resolution are presented

    The prototype phase of the ENUBET positron tagger

    Get PDF
    Understanding the interaction of neutrinos with the other particles of the Standard Model is a fundamental activity in particle physics. The uncertainties on the initial neutrino flux limit the sensitivity on the neutrino cross section measurement in the GeV range to a precision of 10-20%. The scientific goal of the ENUBET project is to improve this sensitivity up to 1% by developing an active decay tunnel, as opposed to traditional neutrino beams, which have a passive decay region. By tagging the positrons emitted in the Ke3 decay (K+ -> π0 + e+ + νe) it is possible to infer the initial neutrino flux. If the tunnel is short enough (about 50 m) the Ke3 decay is the only source of neutrinos. Shashlik calorimeters are suitable to instrument such a tunnel, because they are cost effective, have a good geometrical adaptability and their energy resolution can be tuned with the proper absorbing/scintillator tiles thickness and fiber frequency. To separate the positrons from the pion background these calorimeters are longitudinally segmented with a compact readout based on Silicon PhotoMultipliers embedded in the bulk of the calorimeter itself. This thesis describes the prototyping activity of the ENUBET Collaboration for the positron tagger and the tests performed at the CERN PS-T9 beamline from July 2016 to October 2017. The details of each prototype design and the results in terms of linearity and energy resolution are presented

    Model supporting the use of pressure in the hot slumping of glass substrates for X-ray telescopes

    Get PDF
    Thin glass foils are nowadays considered good substrates for lightweight focusing optics, especially for X-ray telescopes. The desired shape can be imparted to the foils by hot slumping, a process that replicates the shape of a slumping mould. During thermal slumping, when the glass and the mould come into contact, ripples in the glass surface appear spontaneously if the thermal expansions are mismatched. In our hot slumping setup, pressure is applied to ease the mould shape replication and to enhance the ripple relaxation. Starting from an existing model developed to explain the ripple formation in hot-slumped glass foils without pressure, we have developed a model that includes the pressure to support our experimental results

    Next-generation ultra-compact calorimeters based on oriented crystals

    Get PDF
    Calorimeters based on oriented crystals provide unparalleled compactness and resolution in measuring the energy of electromagnetic particles. Recent experiments performed at CERN and DESY beamlines by the AXIAL/ELIOT experiments demonstrated a significant reduction in the radiation length inside tungsten and PbWO4, the latter being the scintillator used for the CMS ECAL, observed when the incident particle trajectory is aligned with a lattice axis within ∼1∘. This remarkable effect, being observed over the wide energy range from a few GeV to 1 TeV or higher, paves the way for the development of innovative calorimeters based on oriented crystals, featuring a design significantly more compact than currently achievable while rivaling the current state of the art in terms of energy resolution in the range of interest for present and future forward detectors (such as the KLEVER Small Angle Calorimeter at CERN SPS) and source-pointing space-borne γ-ray telescopes

    Colorectal Cancer Stage at Diagnosis Before vs During the COVID-19 Pandemic in Italy

    Get PDF
    IMPORTANCE Delays in screening programs and the reluctance of patients to seek medical attention because of the outbreak of SARS-CoV-2 could be associated with the risk of more advanced colorectal cancers at diagnosis. OBJECTIVE To evaluate whether the SARS-CoV-2 pandemic was associated with more advanced oncologic stage and change in clinical presentation for patients with colorectal cancer. DESIGN, SETTING, AND PARTICIPANTS This retrospective, multicenter cohort study included all 17 938 adult patients who underwent surgery for colorectal cancer from March 1, 2020, to December 31, 2021 (pandemic period), and from January 1, 2018, to February 29, 2020 (prepandemic period), in 81 participating centers in Italy, including tertiary centers and community hospitals. Follow-up was 30 days from surgery. EXPOSURES Any type of surgical procedure for colorectal cancer, including explorative surgery, palliative procedures, and atypical or segmental resections. MAIN OUTCOMES AND MEASURES The primary outcome was advanced stage of colorectal cancer at diagnosis. Secondary outcomes were distant metastasis, T4 stage, aggressive biology (defined as cancer with at least 1 of the following characteristics: signet ring cells, mucinous tumor, budding, lymphovascular invasion, perineural invasion, and lymphangitis), stenotic lesion, emergency surgery, and palliative surgery. The independent association between the pandemic period and the outcomes was assessed using multivariate random-effects logistic regression, with hospital as the cluster variable. RESULTS A total of 17 938 patients (10 007 men [55.8%]; mean [SD] age, 70.6 [12.2] years) underwent surgery for colorectal cancer: 7796 (43.5%) during the pandemic period and 10 142 (56.5%) during the prepandemic period. Logistic regression indicated that the pandemic period was significantly associated with an increased rate of advanced-stage colorectal cancer (odds ratio [OR], 1.07; 95%CI, 1.01-1.13; P = .03), aggressive biology (OR, 1.32; 95%CI, 1.15-1.53; P < .001), and stenotic lesions (OR, 1.15; 95%CI, 1.01-1.31; P = .03). CONCLUSIONS AND RELEVANCE This cohort study suggests a significant association between the SARS-CoV-2 pandemic and the risk of a more advanced oncologic stage at diagnosis among patients undergoing surgery for colorectal cancer and might indicate a potential reduction of survival for these patients

    The prototype phase of the ENUBET positron tagger

    No full text
    Understanding the interaction of neutrinos with the other particles of the Standard Model is a fundamental activity in particle physics. The uncertainties on the initial neutrino flux limit the sensitivity on the neutrino cross section measurement in the GeV range to a precision of 10-20%. The scientific goal of the ENUBET project is to improve this sensitivity up to 1% by developing an active decay tunnel, as opposed to traditional neutrino beams, which have a passive decay region. By tagging the positrons emitted in the Ke3 decay (K+ -> π0 + e+ + νe) it is possible to infer the initial neutrino flux. If the tunnel is short enough (about 50 m) the Ke3 decay is the only source of neutrinos. Shashlik calorimeters are suitable to instrument such a tunnel, because they are cost effective, have a good geometrical adaptability and their energy resolution can be tuned with the proper absorbing/scintillator tiles thickness and fiber frequency. To separate the positrons from the pion background these calorimeters are longitudinally segmented with a compact readout based on Silicon PhotoMultipliers embedded in the bulk of the calorimeter itself. This thesis describes the prototyping activity of the ENUBET Collaboration for the positron tagger and the tests performed at the CERN PS-T9 beamline from July 2016 to October 2017. The details of each prototype design and the results in terms of linearity and energy resolution are presented

    Enhanced electromagnetic radiation in oriented scintillating crystals at the 100-MeV and sub-GeV scales

    No full text
    Nowadays, it is well known that the electromagnetic interaction between high-energy particles and matter experiences substantial modifications when the latter consists of a crystalline medium and its lattice axes are almost parallel to the input beam direction. In particular, a strong boost to the cross section of bremsstrahlung by electrons and positrons in high-density oriented crystals has been observed in the 1010-to-100 mathrmGeV100~mathrm{GeV} regime. This effect proves particularly appealing when it comes to inorganic scintillators, given the possibility to exploit it for the development of high-performance, ultra-compact electromagnetic calorimeters. This work provides a detailed discussion of the results obtained by probing a PWO (lead tungstate) oriented sample with 120 mathrmGeV/c120~mathrm{GeV}/c electrons and positrons at the CERN North Area: in particular, a comparison between the outcomes obtained with electrons and positrons is made. Moreover, output radiation measurements on a thinner oriented PWO sample have been recently performed in the sub-GeV regime at the MAMI-B facility: an overview on the resulting characterisation is given
    corecore