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7 results on '"M. Chiappini"'

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. The ultra light Drift Chamber of the MEG II experiment

Author

C. Voena, Luca Galli, M. Francesconi, M. Meucci, Giovanni Signorelli, G. Chiarello, C. Pinto, Angela Papa, A. M. Baldini, M. Panareo, F. Grancagnolo, Fabrizio Cei, A. Miccoli, A. Corvaglia, F. Renga, Marco Grassi, G. Cavoto, M. Hildebrandt, F. Raffaelli, Donato Nicolo, M. Chiappini, G. Tassielli, Baldini, A. M., Cavoto, G., Cei, F., Chiappini, M., Chiarello, G., Corvaglia, A., Francesconi, M., Galli, L., Grancagnolo, F., Grassi, M., Hildebrandt, M., Meucci, M., Miccoli, A., Nicolo, D., Papa, A., Panareo, M., Pinto, C., Raffaelli, F., Renga, F., Signorelli, G., Tassielli, G. F., and Voena, C.

Subjects
Nuclear and High Energy Physics, cLFV, Drift chamber, Gas detectors, MEGII, Tracking, Phase (waves), chemistry.chemical_element, Tracking (particle physics), 01 natural sciences, Radiation length, Gas detector, 0103 physical sciences, 010306 general physics, Instrumentation, Helium, Physics, 010308 nuclear & particles physics, Branching fraction, Detector, Radius, chemistry, Atomic physics, Lepton
Abstract

The MEG experiment at the Paul Scherrer Institute searches for the charged Lepton Flavor Violating μ + → e + γ decay. MEG has already determined in a first data taking phase the world best upper limit on the branching ratio: BR ( μ + → e + γ ) 4 . 2 × 1 0 − 13 An upgrade of the whole detector has been approved to obtain a substantial increase in sensitivity. Currently MEG is in upgrade phases, this phase involves all the detectors. The new positron tracker is a high transparency single volume, fully stereo cylindrical Drift Chamber (CDCH), immersed in a non uniform longitudinal B-field, with length of 1 . 93 m, internal radius of 17 cm and external radius of 30 cm. It is composed of 9 concentric layers, divided into 12 identical sector of 16 drift cells. The single drift cell is approximately square, with a 20 μ m gold plated W sense wire surrounded by 40 μ m silver plated Al field wires in a ratio of 5:1. The total number of wires amounts to 11904 for an equivalent radiation length per track turn of about 1.5x10−3 X0 when the chamber is filled with a gas mixture of helium and iso-butane. Due to the high wire density ( 12 w i r e s ∕ cm 2 ), the use of the classical feed-through technique as wire anchoring system could hardly be implemented and therefore it was necessary to develop new wiring strategies. The number of wires and the stringent requirements impose the use of an automatic system (wiring robot) to operate the wiring procedures. Several tests have been performed in different prototypes of the drift chamber, exposed to cosmic rays, test beams and radioactive sources, to fulfill the requirement on the spatial resolution to be less than 110 μ m. In this paper we describe the CDCH construction and the first tests during the 2018 Engineering Run.

Published
2019

3. Low latency serial communication for MEG II trigger system

Author

U. Hartmann, Luca Galli, Stefan Ritt, F. Cei, E. Schmid, M. Francesconi, M. Chiappini, A. M. Baldini, Giovanni Signorelli, Donato Nicolo, Angela Papa, Fabio Morsani, and Marco Grassi

Subjects
Physics, Nuclear and High Energy Physics, Finite-state machine, Frontend, 010308 nuclear & particles physics, business.industry, Serial communication, Transmitter, Low latency, Serial links, 01 natural sciences, DAQ and data management, Data flow diagram, Trigger, Proof of concept, 0103 physical sciences, Waveform, Latency (engineering), 010306 general physics, business, Instrumentation, Computer hardware, Shift register
Abstract

In the framework of the upgrade of the MEG experiment a new trigger system with demanding performances in terms of latency was designed. To achieve the goal of 512 ns latency the serial connections between trigger boards have been optimized so that they only rely on serial to parallel shift registers for the data flow, minimizing the amount of logic to be crossed by data. A dedicated Finite State Machine (FSM) was designed to select the sampling point of the serial stream with respect to an external precision clock used by both transmitter and receiver. As a proof of concept a 16 000 channel weighted waveform sum including pedestal suppression, was computed, resulting in 700 ns of latency.

Published
2019
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4. The new drift chamber of the MEG II experiment

Author

Marco Grassi, G. Tassielli, G. Cavoto, F. Renga, F. Grancagnolo, G. Chiarello, C. Voena, Luca Galli, Fabrizio Cei, M. Hildebrandt, Donato Nicolo, F. Raffaelli, A. M. Baldini, Giovanni Signorelli, M. Panareo, M. Francesconi, Angela Papa, M. Chiappini, Chiappini, M., Baldini, A. M., Cavoto, G., Cei, F., Chiarello, G., Francesconi, M., Galli, L., Grancagnolo, F., Grassi, M., Hildebrandt, M., Nicolò, D., Panareo, M., Papa, A., Raffaelli, F., Renga, F., Signorelli, G., Tassielli, G. F., and Voena, C.

Subjects
Nuclear and High Energy Physics, Physics - Instrumentation and Detectors, Phase (waves), FOS: Physical sciences, 01 natural sciences, Radiation length, High Energy Physics - Experiment, Drift chambers, Gas detectors, MEG II experiment, Tracking detectors, Momentum, High Energy Physics - Experiment (hep-ex), 0103 physical sciences, 010306 general physics, Instrumentation, High rate, Physics, Tracking detectors, Gas detectors, Drift chambers, MEG II experiment, 010308 nuclear & particles physics, Resolution (electron density), Detector, Instrumentation and Detectors (physics.ins-det), High Energy Physics::Experiment, Atomic physics, Sensitivity (electronics), Lepton
Abstract

This article presents the MEG II Cylindrical Drift CHamber (CDCH), a key detector for the phase 2 of MEG, which aims at reaching a sensitivity level of the order of $6 \times 10^{-14}$ for the charged Lepton Flavour Violating $\mu^+ \rightarrow \mbox{e}^+ \gamma$ decay. CDCH is designed to overcome the limitations of the MEG $\mbox{e}^+$ tracker and guarantee the proper operation at high rates with long-term detector stability. CDCH is a low-mass unique volume detector with high granularity: 9 layers of 192 drift cells, few mm wide, defined by $\approx 12000$ wires in a stereo configuration for longitudinal hit localization. The total radiation length is $1.5 \times 10^{-3}$ $\mbox{X}_0$, thus minimizing the Multiple Coulomb Scattering (MCS) contribution and allowing for a single-hit resolution of 110 $\mu$m and a momentum resolution of 130 keV/c. CDCH integration into the MEG II experimental apparatus will start in this year., Comment: 2 pages, 3 figures, proceeding at PisaMeeting2018 conference, published in NIMA

Published
2019
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5. The design of the MEG II experiment: MEG II Collaboration

Author

G. Cavoto, Stefan Ritt, P. W. Cattaneo, A. D’Onofrio, F. Morsani, Yu.V. Yudin, C. Voena, Masatoshi Maki, K. Ieki, S. Nakaura, Flavio Gatti, T. Libeiro, A. S. Korenchenko, F. Berg, Marco Francesconi, Ryu Sawada, G. F. Tassielli, A. Mtchedilishvili, F. Ignatov, D. Nicolò, C. Bemporad, G. Chiarello, Fabrizio Cei, A. Papa, D. N. Grigoriev, G. Signorelli, Nobuo Matsuzawa, M. Usami, Marco Grassi, Toshinori Mori, M. Simonetta, Andrey Popov, L. Galli, M. Nakao, P.-R. Kettle, A. Pepino, N. P. Kravchuk, Hajime Nishiguchi, A. de Bari, B.I. Khazin, Yusuke Uchiyama, F. Raffaelli, T. Iwamoto, W. R. Molzon, N. V. Khomutov, E. Baracchini, Satoshi Mihara, M. Panareo, D. Kaneko, Y. Zhang, S. Ogawa, A. Corvaglia, Kayo Yoshida, Malte Hildebrandt, G. Piredda, A. M. Baldini, M. Milgie, Wataru Ootani, M. De Gerone, C. Chiri, M. Rossella, Z. Hodge, R. Iwai, Yuki Fujii, Katsuyu Kasami, M. Venturini, M. Nishimura, Gianluigi Boca, F. Grancagnolo, F. Renga, Michele Biasotti, M. Chiappini, G. Rutar, E. Ripiccini, G. Cocciolo, Baldini, A. M., Baracchini, E., Bemporad, C., Berg, F., Biasotti, M., Boca, G., Cattaneo, P. W., Cavoto, G., Cei, F., Chiappini, M., Chiarello, G., Chiri, C., Cocciolo, G., Corvaglia, A., de Bari, A., De Gerone, M., D’Onofrio, A., Francesconi, M., Fujii, Y., Galli, L., Gatti, F., Grancagnolo, F., Grassi, M., Grigoriev, D. N., Hildebrandt, M., Hodge, Z., Ieki, K., Ignatov, F., Iwai, R., Iwamoto, T., Kaneko, D., Kasami, K., Kettle, P. -R., Khazin, B. I., Khomutov, N., Korenchenko, A., Kravchuk, N., Libeiro, T., Maki, M., Matsuzawa, N., Mihara, S., Milgie, M., Molzon, W., Mori, Toshinori, Morsani, F., Mtchedilishvili, A., Nakao, M., Nakaura, S., Nicolò, D., Nishiguchi, H., Nishimura, M., Ogawa, S., Ootani, W., Panareo, M., Papa, A., Pepino, A., Piredda, G., Popov, A., Raffaelli, F., Renga, F., Ripiccini, E., Ritt, S., Rossella, M., Rutar, G., Sawada, R., Signorelli, G., Simonetta, M., Tassielli, G. F., Uchiyama, Y., Usami, M., Venturini, M., Voena, C., Yoshida, K., Yudin, Yu. V., and Zhang, Y.

Subjects
SUSY SO(10), Physics and Astronomy (miscellaneous), High Energy Pysics, muons, charged lepton flavor violation, particles detectors, LEPTON-FLAVOR VIOLATION, SUPERSYMMETRIC STANDARD MODEL, SCINTILLATION-COUNTERS, PLASTIC SCINTILLATOR, UNIFIED THEORIES, TIME RESOLUTION, NEUTRINO-MASS, HIGGS-BOSON, 50 PS, 01 natural sciences, Muon Decay Violating Decay, Nuclear physics, 0103 physical sciences, Sensitivity (control systems), Engineering (miscellaneous), 010306 general physics, Physics, 010308 nuclear & particles physics, Branching fraction, Detector, Gamma ray, Upgrade, Order of magnitude
Abstract

The MEG experiment, designed to search for the μ+→e+γ decay, completed data-taking in 2013 reaching a sensitivity level of 5.3×10^−13 for the branching ratio. In order to increase the sensitivity reach of the experiment by an order of magnitude to the level of 6×10^−14, a total upgrade, involving substantial changes to the experiment, has been undertaken, known as MEG II. We present both the motivation for the upgrade and a detailed overview of the design of the experiment and of the expected detector performance

Published
2018

6. 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

7. Single-hit resolution measurement with MEG II drift chamber prototypes

Author

Fabrizio Cei, M. Venturini, E. Ripiccini, C. Chiri, Marco Grassi, V. Martinelli, E. Baracchini, F. Renga, A. Pepino, F. Tenchini, G. Piredda, G. Chiarello, M. Chiappini, Michele Cascella, L. Galli, S. Dussoni, A. M. Baldini, C. Voena, G. F. Tassielli, D. Nicoló, F. Grancagnolo, G. Signorelli, G. Cavoto, M. Panareo, Baldini, A. M., Baracchini, E., Cavoto, G., Cascella, M., Cei, F., Chiappini, M., Chiarello, Gianluigi, Chiri, Claudio, Dussoni, S., Galli, L., Grancagnolo, F., Grassi, M., Martinelli, V., Nicolò, D., Panareo, Marco, Pepino, Aurora, Piredda, G., Renga, F., Ripiccini, E., Signorelli, G., Tassielli, GIOVANNI FRANCESCO, Tenchini, F., Venturini, M., and Voena, C.

Subjects
Materials science, Physics - Instrumentation and Detectors, Physics::Instrumentation and Detectors, chemistry.chemical_element, FOS: Physical sciences, Cosmic ray, muon decay, Tracking (particle physics), lepton flavour violation, 01 natural sciences, Particle detector, High Energy Physics - Experiment, High Energy Physics - Experiment (hep-ex), Optics, Ionization, 0103 physical sciences, 010306 general physics, Instrumentation, Image resolution, Mathematical Physics, Helium, 010308 nuclear & particles physics, business.industry, Drift chambers, primary ionisation, MEG, tracker, hit resolution, Instrumentation and Detectors (physics.ins-det), Charged particle, chemistry, Measuring instrument, business
Abstract

Drift chambers operated with helium-based gas mixtures represent a common solution for tracking charged particles keeping the material budget in the sensitive volume to a minimum. The drawback of this solution is the worsening of the spatial resolution due to primary ionisation fluctuations, which is a limiting factor for high granularity drift chambers like the MEG II tracker. We report on the measurements performed on three different prototypes of the MEG II drift chamber aimed at determining the achievable single-hit resolution. The prototypes were operated with helium/isobutane gas mixtures and exposed to cosmic rays, electron beams and radioactive sources. Direct measurements of the single hit resolution performed with an external tracker returned a value of 110 $\mu$m, consistent with the values obtained with indirect measurements performed with the other prototypes., Comment: 18 pages, 18 figures

Published
2016
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