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9 results on '"C. Chiri"'

1. Search for lepton flavour violating muon decay mediated by a new light particle in the MEG experiment

Author

A. Stoykov, Valerio Pettinacci, Andrey Popov, S. Ogawa, Toshinori Mori, Stefan Ritt, K. Ieki, G. F. Tassielli, N. P. Kravchuk, Satoru Kobayashi, M. Panareo, M. De Gerone, P. Schwendimann, Malte Hildebrandt, Flavio Gatti, A. Papa, G. Pizzigoni, M. Francesconi, William Kyle, T. Libeiro, M. Usami, W. R. Molzon, Michele Biasotti, Yusuke Uchiyama, M. Chiappini, Satoshi Mihara, D. Nicolò, R. Onda, Dylan Palo, P.-R. Kettle, G. M. A. Lim, N. V. Khomutov, L. Galli, M. Nakao, Vladimir Malyshev, M. Nishimura, F. Ignatov, A. Kolesnikov, C. Chiri, Gianluigi Boca, F. Renga, Atsushi Oya, Ryu Sawada, G. Signorelli, A. de Bari, F. Grancagnolo, G. Cavoto, P. W. Cattaneo, H. Natori, Z. Hodge, R. Iwai, Yu.V. Yudin, Fabrizio Cei, F. Berg, Kazuki Toyoda, T. Iwamoto, M. Rossella, K. Yanai, Marco Grassi, Wataru Ootani, C. Voena, A. Corvaglia, A. M. Baldini, Nikolay Kuchinskiy, Aleksander Rozhdestvensky, Hajime Nishiguchi, Manuel Meucci, G. Chiarello, D. N. Grigoriev, A. Mtchedilishvili, Nobuo Matsuzawa, Baldini, A. M., Berg, F., Biasotti, M., Boca, G., Cattaneo, P. W., Cavoto, G., Cei, F., Chiappini, M., Chiarello, G., Chiri, C., Corvaglia, A., de Bari, A., De Gerone, M., Francesconi, M., Galli, L., Gatti, F., Grancagnolo, F., Grassi, M., Grigoriev, D. N., Hildebrandt, M., Hodge, Z., Ieki, K., Ignatov, F., Iwai, R., Iwamoto, T., Kobayashi, S., Kettle, P. -R., Kyle, W., Khomutov, N., Kolesnikov, A., Kravchuk, N., Kuchinskiy, N., Libeiro, T., Lim, G. M. A., Malyshev, V., Matsuzawa, N., Meucci, M., Mihara, S., Molzon, W., Mori, Toshinori, Mtchedilishvili, A., Nakao, M., Natori, H., Nicolò, D., Nishiguchi, H., Nishimura, M., Ogawa, S., Onda, R., Ootani, W., Oya, A., Palo, D., Panareo, M., Papa, A., Pettinacci, V., Pizzigoni, G., Popov, A., Renga, F., Ritt, S., Rozhdestvensky, A., Rossella, M., Sawada, R., Schwendimann, P., Signorelli, G., Stoykov, A., Tassielli, G. F., Toyoda, K., Uchiyama, Y., Usami, M., Voena, C., Yanai, K., and Yudin, Yu. V.

Subjects
Particle physics, Physics and Astronomy (miscellaneous), Flavour, Light particle, FOS: Physical sciences, lcsh:Astrophysics, MEG experiment, lepton flavour violation, muon decay, 01 natural sciences, High Energy Physics - Experiment, High Energy Physics - Experiment (hep-ex), 0103 physical sciences, lcsh:QB460-466, Direct search, lcsh:Nuclear and particle physics. Atomic energy. Radioactivity, Lepton Flavour Violation, MEG experiment, 010306 general physics, Engineering (miscellaneous), Physics, Muon, 010308 nuclear & particles physics, Branching fraction, lcsh:QC770-798, High Energy Physics::Experiment, Lepton Flavour Violation, Lepton
Abstract

We present the first direct search for lepton flavour violating muon decay mediated by a new light particle X, $$\upmu ^+ \rightarrow \mathrm {e}^+\mathrm {X}, \mathrm {X} \rightarrow \upgamma \upgamma \ $$ μ + → e + X , X → γ γ . This search uses a dataset resulting from $$7.5\times 10^{14}$$ 7.5 × 10 14 stopped muons collected by the MEG experiment at the Paul Scherrer Institut in the period 2009–2013. No significant excess is found in the mass region 20–45 MeV/c$$^2$$ 2 for lifetimes below 40 ps, and we set the most stringent branching ratio upper limits in the mass region of 20–40 MeV/c$$^2$$ 2 , down to $${\mathcal {O}}(10^{-11})$$ O ( 10 - 11 ) at 90% confidence level.

Published
2020
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2. Gas distribution and monitoring for the drift chamber of the MEG II experiment

Author

E. Ripiccini, F. Grancagnolo, M. Meucci, A. M. Baldini, E. Baracchini, M. Panareo, C. Chiri, G. F. Tassielli, M. Hildebrandt, F. Renga, F. Raffaelli, A. Papa, G. Chiarello, B. Pruneti, Fabrizio Cei, V. Martinelli, Marco Grassi, L. Galli, A. Pepino, D. Nicoló, G. Cavoto, Marco Francesconi, C. Voena, M. Chiappini, G. Signorelli, Baldini, A. M., Baracchini, E., Cavoto, G., Cei, F., Chiappini, M., Chiarello, G., Chiri, C., Francesconi, M., Galli, L., Grancagnolo, F., Grassi, M., Hildebrandt, M., Martinelli, V., Meucci, M., Nicolò, D., Panareo, M., Papa, A., Pepino, A., Pruneti, B., Raffaelli, F., Renga, F., Ripiccini, E., Signorelli, G., Tassielli, G. F., and Voena, C.

Subjects
Wire chambers (MWPC, Materials science, Physics - Instrumentation and Detectors, Physics::Instrumentation and Detectors, chemistry.chemical_element, FOS: Physical sciences, 01 natural sciences, Particle detector, High Energy Physics - Experiment, High Energy Physics - Experiment (hep-ex), Gaseous detectors, Positron, 0103 physical sciences, Gas systems and purification, Wire chambers (MWPC, Thin-gap chambers, drift chambers, drift tubes, proportional chambers etc), Instrumentation, Mathematical Physics, Gaseous detector, drift chambers, 010306 general physics, Helium, drift tubes, Muon, 010308 nuclear & particles physics, Detector, Thin-gap chambers, Instrumentation and Detectors (physics.ins-det), Computational physics, chemistry, Townsend discharge, proportional chambers etc), Measuring instrument, Radioactive decay
Abstract

The reconstruction of the positron trajectory in the MEG-II experiment searching for the $\mu^+ \to e^+ \gamma$ decay uses a cylindrical drift chamber operated with a helium-isobutane gas mixture. A stable performance of the detector in terms of its electron drift properties, avalanche multiplication, and with a gas mixture of controlled composition and purity has to be provided and continuously monitored. In this paper we describe the strategies adopted to meet the requirements imposed by the target sensitivity of MEG-II, including the construction and commissioning of a small chamber for an online monitoring of the gas quality., Comment: 12 pages, 6 figures, submitted to Journal of Instrumentation

Published
2018

3. Muon polarization in the MEG experiment: predictions and measurements

Author

A. M. Baldini, Akira Yamamoto, Z. You, M. De Gerone, W. R. Molzon, Malte Hildebrandt, Z. Hodge, B.I. Khazin, Marco Grassi, G. Chiarello, D. N. Grigoriev, Yu Bao, A. Mtchedlishvili, K. Ieki, S. Nakaura, A. Pepino, G. F. Tassielli, G. Cavoto, A. de Bari, T. I. Kang, P. W. Cattaneo, Hajime Nishiguchi, F. Berg, F. Renga, E. Baracchini, Flavio Gatti, A. Papa, Yuki Fujii, Yusuke Uchiyama, T. Haruyama, S. Ogawa, T. Iwamoto, M. Rossella, Andrey Popov, Michele Biasotti, G. M. A. Lim, L. Galli, S. Dussoni, A. S. Korenchenko, G. Pizzigoni, P.-R. Kettle, G. Rutar, E. Ripiccini, F. Grancagnolo, A. D’Onofrio, N. V. Khomutov, Wataru Ootani, Stefan Ritt, N. P. Kravchuk, D. Nicolò, C. Voena, A. Graziosi, F. Ignatov, K. Yoshida, M. Venturini, D. Kaneko, Ryu Sawada, F. Tenchini, G. Piredda, Satoshi Mihara, G. Signorelli, Yu.V. Yudin, M. Nishimura, F. Sergiampietri, Gianluigi Boca, Fabrizio Cei, C. Chiri, M. Panareo, C. Bemporad, and Toshinori Mori

Subjects
Physics, Particle physics, Muon, Physics and Astronomy (miscellaneous), 010308 nuclear & particles physics, High Energy Physics::Phenomenology, Order (ring theory), 7. Clean energy, 01 natural sciences, Standard Model, Massless particle, 0103 physical sciences, Physics::Accelerator Physics, High Energy Physics::Experiment, Production (computer science), Neutrino, 010306 general physics, Engineering (miscellaneous), Energy (signal processing), Lepton
Abstract

The MEG experiment makes use of one of the world's most intense low energy muon beams, in order to search for the lepton flavour violating process $\mu^{+} \rightarrow {\rm e}^{+} \gamma$. We determined the residual beam polarization at the thin stopping target, by measuring the asymmetry of the angular distribution of Michel decay positrons as a function of energy. The initial muon beam polarization at the production is predicted to be $P_{\mu} = -1$ by the Standard Model (SM) with massless neutrinos. We estimated our residual muon polarization to be $P_{\mu} = -0.85 \pm 0.03 ~ {\rm (stat)} ~ { }^{+ 0.04}_{-0.05} ~ {\rm (syst)}$ at the stopping target, which is consistent with the SM predictions when the depolarizing effects occurring during the muon production, propagation and moderation in the target are taken into account. The knowledge of beam polarization is of fundamental importance in order to model the background of our ${\megsign}$ search induced by the muon radiative decay: $\mu^{+} \rightarrow {\rm e}^{+} \bar{\nu}_{\mu} \nu_{\rm e} \gamma$.

Published
2016
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4. A high performance front end for MEG II tracker

Author

G. F. Tassielli, A. Pepino, F. Grancagnolo, M. Panareo, G. Chiarello, C. Chiri, C. Pinto, A. Corvaglia, Chiarello, Gianluigi, Chiri, Claudio, Corvaglia, A., Grancagnolo, F., Panareo, Marco, Pepino, Aurora, Pinto, Carlo, and Tassielli, GIOVANNI FRANCESCO

Subjects
Physics, Muon, Physics::Instrumentation and Detectors, business.industry, Bandwidth (signal processing), Electrical engineering, Front end electronics, Wide Bandwidth, High Speed Electronic, Anode, Front and back ends, Front End, Optics, Positron, Upgrade, Physics::Accelerator Physics, High Energy Physics::Experiment, business, Drift Chamber, Image resolution
Abstract

MEG Experiment Upgrade proposes a major improvement [1] of the sensitivity in the μ →eγ decay [2]. In particular the positron tracking will be performed by means of an upgrade of MEG Drift Chamber that consists in a cylindrical wire drift chamber, with the axis parallel to the muon beam, inspired to the one used in the KLOE experiment [3]. The new tracker, currently under costruction, can achieve a resolution of 100 μm in the measurement of the drift distance to the anode wires. Improving the resolution imposes a high speed and high performance Front End Electronics for signal acquisition. © 2015 IEEE.

Published
2015
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5. Towards the installation and use of an extended array for cosmic ray detection: the EEE Project

Author

F. Librizzi, F. Romano, E. Coccia, A. Maggiora, C. Sbarra, Despina Hatzifotiadou, S. Miozzi, S. De Pasquale, S. An, E. Bressan, Giovanni Imponente, G. Bencivenni, Francesco Noferini, G.S. Pappalardo, Claudio Guarnaccia, Andrea Alici, F. L. Fabbri, R. Moro, A. Zichichi, Chiara Zampolli, C. Gustavino, Giorgio Ivan Russo, R. Antolini, Marcello Abbrescia, Gilda Scioli, M. Garbini, P. La Rocca, Luisa Cifarelli, D. De Gruttola, S. Serci, A. Badalà, Corrado Cicalo, F. Coccetti, G. Piragino, C. Chiri, E. Siddi, F. Blanco, V. Frolov, R. Baldini Ferroli, R. Zuyeuski, Catia Petta, Francesco Riggi, Roberto Preghenella, H. Wenninger, M. D'Incecco, Paolo Pagano, M. Panareo, M. C. S. Williams, H. Menghetti, J. S. Kim, Gabriella Sartorelli, M. Kim, A. De Caro, M. Selvi, A. Chiavassa, Y.W. Baek, M. Abbrescia, A. Alici, S. An, R. Antolini, A. Badala, Y.W. Baek, R. Baldini Ferroli, G. Bencivenni, F. Blanco, E. Bressan, A. Chiavassa, C. Chiri, C. Cicalo, L. Cifarelli, E. Coccia, F. Coccetti, A. De Caro, D. De Gruttola, S. De Pasquale, M. D’Incecco, F.L. Fabbri, V. Frolov, M. Garbini, C. Guarnaccia, C. Gustavino, D. Hatzifotiadou, G. Imponente, J.S. Kimc, M.M. Kim, P. La Rocca, F. Librizzi, A. Maggiora, H. Menghetti, S.Miozzi, R. Moro, F. Noferini, P. Pagano, M. Panareo, G.S. Pappalardo, C. Petta, G. Piragino, R. Preghenella, F. Riggi, F. Romano, G. Russo, G. Sartorelli, C. Sbarra, G. Scioli, M. Selvi, S. Serci, E. Siddi, H. Wenninger, M.C.S. William, C. Zampolli, A. Zichichi, and R. Zuyeuski

Subjects
Physics, Nuclear and High Energy Physics, Muon, Physics::Instrumentation and Detectors, Astrophysics::High Energy Astrophysical Phenomena, Astrophysics::Instrumentation and Methods for Astrophysics, Astronomy, Cosmic ray, Astrophysics::Cosmology and Extragalactic Astrophysics, Atomic and Molecular Physics, and Optics, Particle detector, Radiation flux, Muon flux, Cosmic muons, Lepton
Abstract

The Extreme Energy Events (EEE) project started to use an array of cosmic ray telescopes for muon detection, distributed over the italian territory. The use of such telescopes, based on Multigap Resistive Plate Chambers (MRPC) allows the study of the local muon flux, the detection of cosmic ray showers and the search for correlations between distant showers. The project is also intended to involve high school teams in an advanced research work. The present status of the installation and the first physics results are discussed here.

Published
2009

6. EEE project: Science in the schools

Author

Fabrizio Fabbri, G. Imponente, H. Menghetti, S. Serci, G. Bencivenni, M. Garbini, G. Sartorelli, Despina Hatzifotiadou, Angela Badala, J. S. Kim, Federica Romano, S. De Pasquale, E. Bressan, Federico Cindolo, E. Coccia, A. Maggiora, R. Zuyenski, F. Blanco, M. Panareo, C. Gustavino, M. Selvi, Luisa Cifarelli, F. Librizzi, R. Moro, V. V. Frolov, C. Sbarra, Francesco Riggi, S. Miozzi, Crispin Williams, G. Piragino, A. Chiavassa, Marcello Abbrescia, R. B. Ferroli, S. An, Antonino Zichichi, C. Chiri, G. S. Pappalardo, M. D'Incecco, P. La Rocca, M., Abbrescia, S., An, R., Antolini, A., Badala', R., BALDINI FERROLI, G., Bencivenni, F., Blanco, E., Bressan, A., Chiavassa, C., Chiri, L., Cifarelli, F., Cindolo, E., Coccia, M., D'Incecco, F. L., Fabbri, V., Frolov, M., Garbini, C., Gustavino, D., Hatzifotiadou, G., Imponente, J., Kim, P., LA ROCCA, F., Librizzi, A., Maggiora, H., Menghetti, S., Miozzi, R., Moro, Panareo, Marco, G. S., Pappalardo, G., Piragino, F., Riggi, F., Romano, G., Sartorelli, C., Sbarra, M., Selvi, S., Serci, C., William, A., Zichichi, and R., Zuveniski

Subjects
Physics, Nuclear and High Energy Physics, Muon, Large Hadron Collider, Radiation, business.industry, Electrical engineering, Cosmic ray, Tracking (particle physics), law.invention, Nuclear physics, Telescope, law, Nuclear electronics, Nuclear Medicine and Imaging, business, Radiology, Nuclear Medicine and Imaging, Radiology, Zenith, Fermi Gamma-ray Space Telescope
Abstract

The EEE (extreme energy event) project will study extensive air showers through the detection of the muon component by means of a network of tracking detectors, installed inside high schools distributed all over Italy. Project's aim is to involve teachers and students in a frontier cosmic ray experiment, as well. The EEE telescope is based on a large but simplified and cheap version of the detector designed for the time of flight measurements (TOF) of the ALICE experiment at LHC: 3 large (~2 m2) multi-gap resistive plate chambers (MRPC), built at CERN by high school students and teachers, which contribute directly to the full operation of the telescope. Using multiple small gas gaps combined with the use of high gain and fast gas mixture (Freon and SF6 based), the MRPCs show a time resolution of the order of 100 ps. Particle tracking is performed equipping MRPCs with 24 strips read, at both ends, by front-end electronics based on NINO ASIC and using commercial multi-hit TDCs. The two-dimensional information on the cosmic muon impact point is obtained by the hit strip, in one direction, and by the time difference of the signals arriving at the two strip ends in the other direction, thus providing space resolution of the order of 1 cm. By using the three impact points it is possible to reconstruct the direction of the crossing muon. The angular resolution obtained for the muon zenith angle is about 1deg. The GPS synchronization of the telescopes will open the way to search for coincidences. The school involvement in the Project started around 2003 with 7 pilot towns. The project, supported by the Ministero dell'Universita e della Ricerca (MIUR), Istituto Nazionale di Fisica Nucleare (INFN), European Organization for Nuclear Research (CERN), Consiglio Nazionale delle Ricerche (CNR) and Museo Storico della Fisica e Centre Studi e Ricerche "E. Fermi", has been conceived and lead by Prof. Antonino Zichichi.

Published
2007

7. Search for the lepton flavour violating decay $$\mu ^+ \rightarrow \mathrm {e}^+ \gamma $$ µ + ? e + ? with the full dataset of the MEG experimentMEG Collaboration

Author

Toshinori Mori, M. Hildebrandt, Donato Nicolo, N. V. Khomutov, T. I. Kang, Francesco Grancagnolo, Z. Hodge, G. Boca, Marco Grassi, A. Mtchedilishvili, A. Pepino, Akira Yamamoto, A. Popov, Roberto Di Nardo, E. Baracchini, A. Corvaglia, D. Mzavia, G. Tassielli, Flavio Gatti, M. De Gerone, S. Ogawa, J. Egger, Fabio Morsani, A. Maki, Michele Biasotti, Yasunori Fujii, Satoshi Mihara, F. Berg, S. Nakaura, C. Voena, G. Rutar, E. Ripiccini, N. Kravchuk, G. M. A. Lim, Angela Papa, Wataru Ootani, C. Chiri, A. S. Korenchenko, G. Pizzigoni, D. Zanello, F. Ignatov, B.I. Khazin, C. Bemporad, Yury V. Yudin, S. Orito, Yusuke Uchiyama, S. Dussoni, A. D’Onofrio, T. Iwamoto, F. Renga, F. Sergiampietri, A. Graziosi, P.R. Kettle, G. Chiarello, Hajime Nishiguchi, M. Venturini, D. N. Grigoriev, Ryu Sawada, M. Nishimura, G. Signorelli, Fabrizio Cei, F. Tenchini, G. Cavoto, G. Piredda, Yu Bao, W. R. Molzon, Z. You, Michele Cascella, Roberto Pazzi, Tadayoshi Doke, P. W. Cattaneo, A. M. Baldini, M. Panareo, L. Galli, F. Raffaelli, Kayo Yoshida, Stefan Ritt, C. Cerri, K. Ieki, M. Simonetta, A. de Bari, Tomiyoshi Haruyama, D. Kaneko, and M. Rossella

Subjects
Physics, Particle physics, Antiparticle, Muon, Physics and Astronomy (miscellaneous), 010308 nuclear & particles physics, Branching fraction, High Energy Physics::Phenomenology, Elementary particle, 01 natural sciences, Lepton number, Nuclear physics, Particle decay, Antimatter, 0103 physical sciences, High Energy Physics::Experiment, 010306 general physics, Engineering (miscellaneous), Lepton
Abstract

The final results of the search for the lepton flavour violating decay $$\mathrm {\mu }^+ \rightarrow \mathrm {e}^+ \mathrm {\gamma }$$ based on the full dataset collected by the MEG experiment at the Paul Scherrer Institut in the period 2009–2013 and totalling $$7.5\times 10^{14}$$ stopped muons on target are presented. No significant excess of events is observed in the dataset with respect to the expected background and a new upper limit on the branching ratio of this decay of $$ \mathcal{B} (\mu ^+ \rightarrow \mathrm{e}^+ \gamma ) < 4.2 \times 10^{-13}$$ (90 % confidence level) is established, which represents the most stringent limit on the existence of this decay to date.

Published
2016
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8. Measurement of the radiative decay of polarized muons in the MEG experiment

Author

S. Nakaura, K. Ieki, G. M. A. Lim, P.-R. Kettle, B.I. Khazin, N. V. Khomutov, G. Signorelli, A. M. Baldini, F. Tenchini, G. Piredda, Yuki Fujii, Wataru Ootani, M. De Gerone, Yusuke Uchiyama, E. Baracchini, W. R. Molzon, T. Haruyama, Z. Hodge, A. Mtchedlishvili, Malte Hildebrandt, Michele Biasotti, G. F. Tassielli, S. Ogawa, G. Chiarello, D. N. Grigoriev, A. D’Onofrio, A. Papa, A. de Bari, Akira Yamamoto, Z. You, F. Berg, C. Voena, G. Rutar, E. Ripiccini, A. Graziosi, C. Bemporad, Ryu Sawada, T. Iwamoto, S. Dussoni, Toshinori Mori, F. Ignatov, Yu Bao, A. S. Korenchenko, G. Pizzigoni, F. Sergiampietri, D. Nicolò, Marco Grassi, A. Pepino, P. W. Cattaneo, F. Renga, Stefan Ritt, Andrey Popov, M. Panareo, Hajime Nishiguchi, G. Cavoto, Yu.V. Yudin, Tae Im Kang, L. Galli, M. Rossella, Fabrizio Cei, Satoshi Mihara, N. P. Kravchuk, C. Chiri, D. Kaneko, F. Grancagnolo, K. Yoshida, M. Venturini, M. Nishimura, Gianluigi Boca, Flavio Gatti, Baldini, A. M., Bao, Y., Baracchini, E., Bemporad, C., Berg, F., Biasotti, M., Boca, G., Cattaneo, P. W., Cavoto, G., Cei, F., Chiarello, Gianluigi, Chiri, Claudio, de Bari, A., De Gerone, M., D’Onofrio, A., Dussoni, S., Fujii, Y., Galli, L., Gatti, F., Grancagnolo, F., Grassi, M., Graziosi, A., Grigoriev, D. N., Haruyama, T., Hildebrandt, M., Hodge, Z., Ieki, K., Ignatov, F., Iwamoto, T., Kaneko, D., Kang, Tae Im, Kettle, P. R., Khazin, B. I., Khomutov, N., Korenchenko, A., Kravchuk, N., Lim, G. M. A., Mihara, S., Molzon, W., Mori, Toshinori, Mtchedlishvili, A., Nakaura, S., Nicolò, D., Nishiguchi, H., Nishimura, M., Ogawa, S., Ootani, W., Panareo, Marco, Papa, A., Pepino, Aurora, Piredda, G., Pizzigoni, G., Popov, A., Renga, F., Ripiccini, E., Ritt, S., Rossella, M., Rutar, G., Sawada, R., Sergiampietri, F., Signorelli, G., Tassielli, GIOVANNI FRANCESCO, Tenchini, F., Uchiyama, Y., Venturini, M., Voena, C., Yamamoto, A., Yoshida, K., You, Z., and Yudin, Y. u. V.

Subjects
Particle physics, Antiparticle, Physics - Instrumentation and Detectors, Engineering (miscellaneous), Physics and Astronomy (miscellaneous), muon physics, FOS: Physical sciences, Elementary particle, 01 natural sciences, High Energy Physics - Experiment, High Energy Physics - Experiment (hep-ex), Particle decay, High Energy Physics - Phenomenology (hep-ph), 0103 physical sciences, MC Simulation, SM Expectation, Muon Decay, Individual Uncertainty Source, Photon Energy Spectrum, Photon Detection Efficiency, Neutral Pion, Total Covariance Matrix, Acceptance Factor, Signal Window, QED Correction, Liquid Xenon, Kinematic Region, 010306 general physics, Physics, Muon, 010308 nuclear & particles physics, Branching fraction, Instrumentation and Detectors (physics.ins-det), Orientation (vector space), High Energy Physics - Phenomenology, High Energy Physics::Experiment, Dimensionless quantity, Lepton
Abstract

We studied the radiative muon decay $\mu^+ \to e^+\nu\bar{\nu}\gamma$ by using for the first time an almost fully polarized muon source. We identified a large sample (~13000) of these decays in a total sample of 1.8x10^14 positive muon decays collected in the MEG experiment in the years 2009--2010 and measured the branching ratio B($\mu^+ \to e^+\nu\bar{\nu}\gamma$) = (6.03+-0.14(stat.)+-0.53(sys.))x10^-8 for E_e > 45 MeV and E_{\gamma} > 40 MeV, consistent with the Standard Model prediction. The precise measurement of this decay mode provides a basic tool for the timing calibration, a normalization channel, and a strong quality check of the complete MEG experiment in the search for $\mu^+ \to e^+\gamma$ process., Comment: 8 pages, 7 figures. Added an introduction to NLO calculation which was recently calculated. Published version

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9. The measuring systems of the wire tension for the MEG II Drift Chamber by means of the resonant frequency technique

Author

A.M. Baldini, H. Benmansour, G. Cavoto, F. Cei, M. Chiappini, G. Chiarello, C. Chiri, G. Cocciolo, A. Corvaglia, F. Cuna, M. Francesconi, L. Galli, F. Grancagnolo, M. Grassi, M. Meucci, A. Miccoli, D. Nicoló, M. Panareo, A. Papa, C. Pinto, F. Raffaelli, F. Renga, G. Signorelli, G.F. Tassielli, A. Venturini, B. Vitali, C. Voena, Baldini, A. M., Benmansour, H., Cavoto, G., Cei, F., Chiappini, M., Chiarello, G., Chiri, C., Cocciolo, G., Corvaglia, A., Cuna, F., Francesconi, M., Galli, L., Grancagnolo, F., Grassi, M., Meucci, M., Miccoli, A., Nicoló, D., Panareo, M., Papa, A., Pinto, C., Raffaelli, F., Renga, F., Signorelli, G., Tassielli, G. F., Venturini, A., Vitali, B., and Voena, C.

Subjects
Nuclear and High Energy Physics, Physics - Instrumentation and Detectors, muon, drift chamber, FOS: Physical sciences, Instrumentation and Detectors (physics.ins-det), charged lepton flavour violation, gas detector, Instrumentation, Drift Chambers, Drift Chambers, Resonance, Measurement of mechanical tension
Abstract

The ultra-low mass cylindrical drift chamber designed for the MEG II experiment is a challenging apparatus made of 1728 phi = 20 micron gold plated tungsten sense wires, 7680 phi = 40 micron and 2496 phi = 50 micron silver plated aluminum field wires. Because of electrostatic stability requirements all the wires have to be stretched at mechanical tensions of about 25, 19 and 29 g respectively which must be controlled at a level better than 0.5 g. This chamber is presently in acquisition, but during its construction about 100 field wires broke, because of chemical corrosion induced by the atmospheric humidity. On the basis of the experience gained with this chamber we decided to build a new one, equipped with a different type of wires less sensitive to corrosion. The choice of the new wire required a deep inspection of its characteristics and one of the main tools for doing this is a system for measuring the wire tension by means of the resonant frequency technique, which is described in this paper. The system forces the wires to oscillate by applying a sinusoidal signal at a known frequency, and then measures the variation of the capacitance between a wire and a common ground plane as a function of the external signal frequency. We present the details of the measuring system and the results obtained by scanning the mechanical tensions of two samples of MEG II cylindrical drift chamber wires and discuss the possible improvements of the experimental apparatus and of the measuring technique., Comment: Nineteen pages, thirteen figures, published on Nuclear Instruments and Methods A

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