1,532 research outputs found

    Commissioning of the MEG II tracker system

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    The MEG experiment at the Paul Scherrer Institut (PSI) represents the state of the art in the search for the charged Lepton Flavour Violating (cLFV) őľ+‚Üíe+ő≥\mu^+ \rightarrow e^+ \gamma decay. With the phase 1, MEG set the new world best upper limit on the \mbox{BR}(\mu^+ \rightarrow e^+ \gamma) < 4.2 \times 10^{-13} (90% C.L.). With the phase 2, MEG II, the experiment aims at reaching a sensitivity enhancement of about one order of magnitude compared to the previous MEG result. The new Cylindrical Drift CHamber (CDCH) is a key detector for MEG II. CDCH is a low-mass single volume detector with high granularity: 9 layers of 192 drift cells, few mm wide, defined by ‚ąľ12000\sim 12000 wires in a stereo configuration for longitudinal hit localization. The filling gas mixture is Helium:Isobutane (90:10). The total radiation length is 1.5√ó10‚ąí31.5 \times 10^{-3} \mbox{X}_0, thus minimizing the Multiple Coulomb Scattering (MCS) contribution and allowing for a single-hit resolution <120< 120 őľ\mum and an angular and momentum resolutions of 6 mrad and 90 keV/c respectively. This article presents the CDCH commissioning activities at PSI after the wiring phase at INFN Lecce and the assembly phase at INFN Pisa. The endcaps preparation, HV tests and conditioning of the chamber are described, aiming at reaching the final stable working point. The integration into the MEG II experimental apparatus is described, in view of the first data taking with cosmic rays and őľ+\mu^+ beam during the 2018 and 2019 engineering runs. The first gas gain results are also shown. A full engineering run with all the upgraded detectors and the complete DAQ electronics is expected to start in 2020, followed by three years of physics data taking.Comment: 10 pages, 12 figures, 1 table, proceeding at INSTR'20 conference, accepted for publication in JINS

    Displacement power spectrum measurement of a macroscopic optomechanical system at thermal equilibrium

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    The mirror relative motion of a suspended Fabry-Perot cavity is studied in the frequency range 3-10 Hz. The experimental measurements presented in this paper, have been performed at the Low Frequency Facility, a high finesse optical cavity 1 cm long suspended to a mechanical seismic isolation system identical to that one used in the VIRGO experiment. The measured relative displacement power spectrum is compatible with a system at thermal equilibrium within its environmental. In the frequency region above 3 Hz, where seismic noise contamination is negligible, the measurement distribution is stationary and Gaussian, as expected for a system at thermal equilibrium. Through a simple mechanical model it is shown that: applying the fluctuation dissipation theorem the measured power spectrum is reproduced below 90 Hz and noise induced by external sources are below the measurement.Comment: 11 pages, 9 figures, 2 tables, to be submitte

    Memory beyond memory in heart beating: an efficient way to detect pathological conditions

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    We study the long-range correlations of heartbeat fluctuations with the method of diffusion entropy. We show that this method of analysis yields a scaling parameter őī\delta that apparently conflicts with the direct evaluation of the distribution of times of sojourn in states with a given heartbeat frequency. The strength of the memory responsible for this discrepancy is given by a parameter ŌĶ2\epsilon^{2}, which is derived from real data. The distribution of patients in the (őī\delta, ŌĶ2\epsilon^{2})-plane yields a neat separation of the healthy from the congestive heart failure subjects.Comment: submitted to Physical Review Letters, 5 figure

    Design, status and perspective of the Mu2e crystal calorimeter

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    The Mu2e experiment at Fermilab will search for the charged lepton flavor violating process of neutrino-less őľ‚Üíe\mu \to e coherent conversion in the field of an aluminum nucleus. Mu2e will reach a single event sensitivity of about 2.5‚čÖ10‚ąí172.5\cdot 10^{-17} that corresponds to four orders of magnitude improvements with respect to the current best limit. The detector system consists of a straw tube tracker and a crystal calorimeter made of undoped CsI coupled with Silicon Photomultipliers. The calorimeter was designed to be operable in a harsh environment where about 10 krad/year will be delivered in the hottest region and work in presence of 1 T magnetic field. The calorimeter role is to perform őľ\mu/e separation to suppress cosmic muons mimiking the signal, while providing a high level trigger and a seeding the track search in the tracker. In this paper we present the calorimeter design and the latest R&\&D results.Comment: 4 pages, conference proceeding for a presentation held at TIPP'2017. To be published on Springer Proceedings in Physic

    Quality Assurance on a custom SiPMs array for the Mu2e experiment

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    The Mu2e experiment at Fermilab will search for the coherent őľ‚Üíe\mu \to e conversion on aluminum atoms. The detector system consists of a straw tube tracker and a crystal calorimeter. A pre-production of 150 Silicon Photomultiplier arrays for the Mu2e calorimeter has been procured. A detailed quality assur- ance has been carried out on each SiPM for the determination of its own operation voltage, gain, dark current and PDE. The measurement of the mean-time-to-failure for a small random sample of the pro-production group has been also completed as well as the determination of the dark current increase as a function of the ioninizing and non-ioninizing dose.Comment: 4 pages, 10 figures, conference proceeding for NSS-MIC 201

    The Mu2e undoped CsI crystal calorimeter

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    The Mu2e experiment at Fermilab will search for Charged Lepton Flavor Violating conversion of a muon to an electron in an atomic field. The Mu2e detector is composed of a tracker, an electromagnetic calorimeter and an external system, surrounding the solenoid, to veto cosmic rays. The calorimeter plays an important role to provide: a) excellent particle identification capabilities; b) a fast trigger filter; c) an easier tracker track reconstruction. Two disks, located downstream of the tracker, contain 674 pure CsI crystals each. Each crystal is read out by two arrays of UV-extended SiPMs. The choice of the crystals and SiPMs has been finalized after a thorough test campaign. A first small scale prototype consisting of 51 crystals and 102 SiPM arrays has been exposed to an electron beam at the BTF (Beam Test Facility) in Frascati. Although the readout electronics were not the final, results show that the current design is able to meet the timing and energy resolution required by the Mu2e experiment.Comment: 6 pages, 8 figures, proceedings of the "Calorimetry for the high energy frontier (CHEF17)" conference, 2-6 October 2017, Lyon, Franc

    Cabergoline, prolactin and heart

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    Summary Introduction and aim:‚Äā Dopamine agonists have been reported to increase the risk of cardiac valve regurgitation in patients with Parkinson's disease. However, it is unknown whether these drugs might be harmful for patients with hyperprolactinaemia (HyperPRL). The aim of the study was to evaluate whether HyperPRL patients treated with dopamine agonists had a higher prevalence of cardiac valves regurgitation than that of general population. Methods and patients:‚Äā One hundred consecutive patients (79 women, 21 men, mean age 41 ¬Ī 13 years) with HyperPRL during treatment with cabergoline were enrolled in an observational case‚Äďcontrol study and compared with 100 matched normal subjects (controls). Valve regurgitation was assessed by echocardiography according to the American Society of Echocardiography recommendations. Results:‚Äā Seven HyperPRL patients (7%) and six controls (6%) had moderate (grade 3) regurgitation in any valve (p = 0.980). All were asymptomatic and had no signs of cardiac disease. Mean duration of cabergoline treatment was 67 ¬Ī 39 months (range: 3‚Äď199 months). Mean cumulative dose of cabergoline was 279 ¬Ī 301 mg (range: 15‚Äď1327 mg). Moderate valve regurgitation was not associated with the duration of treatment (p = 0.359), with cumulative dose of cabergoline (p = 0.173), with age (p = 0.281), with previous treatment with bromocriptine (p = 0.673) or previous adenomectomy (p = 0.497) in patients with HyperPRL. Discussion:‚Äā In conclusion, treatment with cabergoline was not associated with increased prevalence of cardiac valves regurgitation in patients with HyperPRL. Mean cumulative dose of cabergoline was lower in patients with HyperPRL than that reported to be deleterious for patients with Parkinson's disease: hence, longer follow-up is necessary, particularly in patients receiving weekly doses > 3 mg
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