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291 results on '"Khomutov, N."'

1. Search for the X17 particle in $^{7}\mathrm{Li}(\mathrm{p},\mathrm{e}^+ \mathrm{e}^{-}) ^{8}\mathrm{Be}$ processes with the MEG II detector

Author

The MEG II collaboration, Afanaciev, K., Baldini, A. M., Ban, S., Benmansour, H., Boca, G., Cattaneo, P. W., Cavoto, G., Cei, F., Chiappini, M., Corvaglia, A., Maso, G. Dal, De Bari, A., De Gerone, M., Barusso, L. Ferrari, Francesconi, M., Galli, L., Gallucci, G., Gatti, F., Gerritzen, L., Grancagnolo, F., Grandoni, E. G., Grassi, M., Grigoriev, D. N., Hildebrandt, M., Ignatov, F., Ikeda, F., Iwamoto, T., Karpov, S., Kettle, P. -R., Khomutov, N., Kolesnikov, A., Kravchuk, N., Krylov, V., Kuchinskiy, N., Leonetti, F., Li, W., Malyshev, V., Matsushita, A., Meucci, M., Mihara, S., Molzon, W., Mori, T., Nicolò, D., Nishiguchi, H., Ochi, A., Ootani, W., Oya, A., Palo, D., Panareo, M., Papa, A., Pettinacci, V., Popov, A., Renga, F., Ritt, S., Rossella, M., Scarpellini, A. Rozhdestvensky. S., Schwendimann, P., Signorelli, G., Takahashi, M., Uchiyama, Y., Venturini, A., Vitali, B., Voena, C., Yamamoto, K., Yokota, R., and Yonemoto, T.

Subjects
Nuclear Experiment, High Energy Physics - Experiment
Abstract

The observation of a resonance structure in the opening angle of the electron-positron pairs in the $^{7}$Li(p,\ee) $^{8}$Be reaction was claimed and interpreted as the production and subsequent decay of a hypothetical particle (X17). Similar excesses, consistent with this particle, were later observed in processes involving $^{4}$He and $^{12}$C nuclei with the same experimental technique. The MEG II apparatus at PSI, designed to search for the $\mu^+ \rightarrow \mathrm{e}^+ \gamma$ decay, can be exploited to investigate the existence of this particle and study its nature. Protons from a Cockroft-Walton accelerator, with an energy up to 1.1 MeV, were delivered on a dedicated Li-based target. The $\gamma$ and the e$^{+}$e$^{-}$ pair emerging from the $^8\mathrm{Be}^*$ transitions were studied with calorimeters and a spectrometer, featuring a broader angular acceptance than previous experiments. We present in this paper the analysis of a four-week data-taking in 2023 with a beam energy of 1080 keV, resulting in the excitation of two different resonances with Q-value \SI{17.6}{\mega\electronvolt} and \SI{18.1}{\mega\electronvolt}. No significant signal was found, and limits at \SI{90}{\percent} C.L. on the branching ratios (relative to the $\gamma$ emission) of the two resonances to X17 were set, $R_{17.6} < 1.8 \times 10^{-6} $ and $R_{18.1} < 1.2 \times 10^{-5} $., Comment: 11 pages, 9 figures, submitted to EPJC

Published
2024

2. Detailed Report on the Measurement of the Positive Muon Anomalous Magnetic Moment to 0.20 ppm

Author

Aguillard, D. P., Albahri, T., Allspach, D., Anisenkov, A., Badgley, K., Baeßler, S., Bailey, I., Bailey, L., Baranov, V. A., Barlas-Yucel, E., Barrett, T., Barzi, E., Bedeschi, F., Berz, M., Bhattacharya, M., Binney, H. P., Bloom, P., Bono, J., Bottalico, E., Bowcock, T., Braun, S., Bressler, M., Cantatore, G., Carey, R. M., Casey, B. C. K., Cauz, D., Chakraborty, R., Chapelain, A., Chappa, S., Charity, S., Chen, C., Cheng, M., Chislett, R., Chu, Z., Chupp, T. E., Claessens, C., Convery, M. E., Corrodi, S., Cotrozzi, L., Crnkovic, J. D., Dabagov, S., Debevec, P. T., Di Falco, S., Di Sciascio, G., Donati, S., Drendel, B., Driutti, A., Duginov, V. N., Eads, M., Edmonds, A., Esquivel, J., Farooq, M., Fatemi, R., Ferrari, C., Fertl, M., Fienberg, A. T., Fioretti, A., Flay, D., Foster, S. B., Friedsam, H., Froemming, N. S., Gabbanini, C., Gaines, I., Galati, M. D., Ganguly, S., Garcia, A., George, J., Gibbons, L. K., Gioiosa, A., Giovanetti, K. L., Girotti, P., Gohn, W., Goodenough, L., Gorringe, T., Grange, J., Grant, S., Gray, F., Haciomeroglu, S., Halewood-Leagas, T., Hampai, D., Han, F., Hempstead, J., Hertzog, D. W., Hesketh, G., Hess, E., Hibbert, A., Hodge, Z., Hong, K. W., Hong, R., Hu, T., Hu, Y., Iacovacci, M., Incagli, M., Kammel, P., Kargiantoulakis, M., Karuza, M., Kaspar, J., Kawall, D., Kelton, L., Keshavarzi, A., Kessler, D. S., Khaw, K. S., Khechadoorian, Z., Khomutov, N. V., Kiburg, B., Kiburg, M., Kim, O., Kinnaird, N., Kraegeloh, E., Krylov, V. A., Kuchinskiy, N. A., Labe, K. R., LaBounty, J., Lancaster, M., Lee, S., Li, B., Li, D., Li, L., Logashenko, I., Campos, A. Lorente, Lu, Z., Lucà, A., Lukicov, G., Lusiani, A., Lyon, A. L., MacCoy, B., Madrak, R., Makino, K., Mastroianni, S., Miller, J. P., Miozzi, S., Mitra, B., Morgan, J. P., Morse, W. M., Mott, J., Nath, A., Ng, J. K., Nguyen, H., Oksuzian, Y., Omarov, Z., Osofsky, R., Park, S., Pauletta, G., Piacentino, G. M., Pilato, R. N., Pitts, K. T., Plaster, B., Počanić, D., Pohlman, N., Polly, C. C., Price, J., Quinn, B., Qureshi, M. U. H., Ramachandran, S., Ramberg, E., Reimann, R., Roberts, B. L., Rubin, D. L., Sakurai, M., Santi, L., Schlesier, C., Schreckenberger, A., Semertzidis, Y. K., Shemyakin, D., Sorbara, M., Stapleton, J., Still, D., Stöckinger, D., Stoughton, C., Stratakis, D., Swanson, H. E., Sweetmore, G., Sweigart, D. A., Syphers, M. J., Tarazona, D. A., Teubner, T., Tewsley-Booth, A. E., Tishchenko, V., Tran, N. H., Turner, W., Valetov, E., Vasilkova, D., Venanzoni, G., Volnykh, V. P., Walton, T., Weisskopf, A., Welty-Rieger, L., Winter, P., Wu, Y., Yu, B., Yucel, M., Zeng, Y., and Zhang, C.

Subjects
High Energy Physics - Experiment, High Energy Physics - Phenomenology, Nuclear Experiment
Abstract

We present details on a new measurement of the muon magnetic anomaly, $a_\mu = (g_\mu -2)/2$. The result is based on positive muon data taken at Fermilab's Muon Campus during the 2019 and 2020 accelerator runs. The measurement uses $3.1$ GeV$/c$ polarized muons stored in a $7.1$-m-radius storage ring with a $1.45$ T uniform magnetic field. The value of $ a_{\mu}$ is determined from the measured difference between the muon spin precession frequency and its cyclotron frequency. This difference is normalized to the strength of the magnetic field, measured using Nuclear Magnetic Resonance (NMR). The ratio is then corrected for small contributions from beam motion, beam dispersion, and transient magnetic fields. We measure $a_\mu = 116 592 057 (25) \times 10^{-11}$ (0.21 ppm). This is the world's most precise measurement of this quantity and represents a factor of $2.2$ improvement over our previous result based on the 2018 dataset. In combination, the two datasets yield $a_\mu(\text{FNAL}) = 116 592 055 (24) \times 10^{-11}$ (0.20 ppm). Combining this with the measurements from Brookhaven National Laboratory for both positive and negative muons, the new world average is $a_\mu$(exp) $ = 116 592 059 (22) \times 10^{-11}$ (0.19 ppm)., Comment: 48 pages, 29 figures; 4 pages of Supplement Material; version accepted for publication in Physical Review D

Published
2024

3. A search for $\mu^+\to e^+\gamma$ with the first dataset of the MEG II experiment

Author

MEG II collaboration, Afanaciev, K., Baldini, A. M., Ban, S., Baranov, V., Benmansour, H., Biasotti, M., Boca, G., Cattaneo, P. W., Cavoto, G., Cei, F., Chiappini, M., Chiarello, G., Corvaglia, A., Cuna, F., Maso, G. Dal, De Bari, A., De Gerone, M., Barusso, L. Ferrari, Francesconi, M., Galli, L., Gallucci, G., Gatti, F., Gerritzen, L., Grancagnolo, F., Grandoni, E. G., Grassi, M., Grigoriev, D. N., Hildebrandt, M., Ieki, K., Ignatov, F., Ikeda, F., Iwamoto, T., Karpov, S., Kettle, P. -R., Khomutov, N., Kobayashi, S., Kolesnikov, A., Kravchuk, N., Krylov, V., Kuchinskiy, N., Kyle, W., Libeiro, T., Malyshev, V., Matsushita, A., Meucci, M., Mihara, S., Molzon, W., Mori, Toshinori, Nakao, M., Nicolò, D., Nishiguchi, H., Ochi, A., Ogawa, S., Onda, R., Ootani, W., Oya, A., Palo, D., Panareo, M., Papa, A., Pettinacci, V., Popov, A., Renga, F., Ritt, S., Rossella, M., Rozhdestvensky, A., Schwendimann, P., Shimada, K., Signorelli, G., Takahashi, M., Tassielli, G. F., Toyoda, K., Uchiyama, Y., Usami, M., Venturini, A., Vitali, B., Voena, C., Yamamoto, K., Yanai, K., Yonemoto, T., Yoshida, K., and Yudin, Yu. V.

Subjects
High Energy Physics - Experiment
Abstract

The MEG II experiment, based at the Paul Scherrer Institut in Switzerland, reports the result of a search for the decay $\mu^+\to e^+\gamma$ from data taken in the first physics run in 2021. No excess of events over the expected background is observed, yielding an upper limit on the branching ratio of B($\mu^+\to e^+\gamma$) < $7.5 \times 10^{-13}$ (90% C.L.). The combination of this result and the limit obtained by MEG gives B($\mu^+\to e^+\gamma$) < $3.1 \times 10^{-13}$ (90% C.L.), which is the most stringent limit to date. A ten-fold larger sample of data is being collected during the years 2022-2023, and data-taking will continue in the coming years., Comment: 10 pages, 6 figures. To be published in EPJC

Published
2023

4. Operation and performance of MEG II detector

Author

MEG II Collaboration, Afanaciev, K., Baldini, A. M., Ban, S., Baranov, V., Benmansour, H., Biasotti, M., Boca, G., Cattaneo, P. W., Cavoto, G., Cei, F., Chiappini, M., Chiarello, G., Corvaglia, A., Cuna, F., Maso, G. Dal, De Bari, A., De Gerone, M., Barusso, L. Ferrari, Francesconi, M., Galli, L., Gallucci, G., Gatti, F., Gerritzen, L., Grancagnolo, F., Grandoni, E. G., Grassi, M., Grigoriev, D. N., Hildebrandt, M., Ieki, K., Ignatov, F., Ikeda, F., Iwamoto, T., Karpov, S., Kettle, P. -R., Khomutov, N., Kobayashi, S., Kolesnikov, A., Kravchuk, N., Krylov, V., Kuchinskiy, N., Kyle, W., Libeiro, T., Malyshev, V., Matsushita, A., Meucci, M., Mihara, S., Molzon, W., Mori, Toshinori, Morsani, F., Nakao, M., Nicolò, D., Nishiguchi, H., Ochi, A., Ogawa, S., Onda, R., Ootani, W., Oya, A., Palo, D., Panareo, M., Papa, A., Pettinacci, V., Popov, A., Raffaelli, F., Renga, F., Ritt, S., Rossella, M., Rozhdestvensky, A., Schwendimann, P., Shimada, K., Signorelli, G., Stoykov, A., Takahashi, M., Tassielli, G. F., Toyoda, K., Uchiyama, Y., Usami, M., Venturini, A., Vitali, B., Voena, C., Yamamoto, K., Yanai, K., Yonemoto, T., Yoshida, K., and Yudin, Yu. V.

Subjects
Physics - Instrumentation and Detectors, High Energy Physics - Experiment
Abstract

The MEG II experiment, located at the Paul Scherrer Institut (PSI) in Switzerland, is the successor to the MEG experiment, which completed data taking in 2013. MEG II started fully operational data taking in 2021, with the goal of improving the sensitivity of the mu+ -> e+ gamma decay down to 6e-14 almost an order of magnitude better than the current limit. In this paper, we describe the operation and performance of the experiment and give a new estimate of its sensitivity versus data acquisition time., Comment: 42 pages, 55 figures. Submitted to EPJC

Published
2023

5. Measurement of the Positive Muon Anomalous Magnetic Moment to 0.20 ppm

Author

Aguillard, D. P., Albahri, T., Allspach, D., Anisenkov, A., Badgley, K., Baeßler, S., Bailey, I., Bailey, L., Baranov, V. A., Barlas-Yucel, E., Barrett, T., Barzi, E., Bedeschi, F., Berz, M., Bhattacharya, M., Binney, H. P., Bloom, P., Bono, J., Bottalico, E., Bowcock, T., Braun, S., Bressler, M., Cantatore, G., Carey, R. M., Casey, B. C. K., Cauz, D., Chakraborty, R., Chapelain, A., Chappa, S., Charity, S., Chen, C., Cheng, M., Chislett, R., Chu, Z., Chupp, T. E., Claessens, C., Convery, M. E., Corrodi, S., Cotrozzi, L., Crnkovic, J. D., Dabagov, S., Debevec, P. T., Di Falco, S., Di Sciascio, G., Drendel, B., Driutti, A., Duginov, V. N., Eads, M., Edmonds, A., Esquivel, J., Farooq, M., Fatemi, R., Ferrari, C., Fertl, M., Fienberg, A. T., Fioretti, A., Flay, D., Foster, S. B., Friedsam, H., Froemming, N. S., Gabbanini, C., Gaines, I., Galati, M. D., Ganguly, S., Garcia, A., George, J., Gibbons, L. K., Gioiosa, A., Giovanetti, K. L., Girotti, P., Gohn, W., Goodenough, L., Gorringe, T., Grange, J., Grant, S., Gray, F., Haciomeroglu, S., Halewood-Leagas, T., Hampai, D., Han, F., Hempstead, J., Hertzog, D. W., Hesketh, G., Hess, E., Hibbert, A., Hodge, Z., Hong, K. W., Hong, R., Hu, T., Hu, Y., Iacovacci, M., Incagli, M., Kammel, P., Kargiantoulakis, M., Karuza, M., Kaspar, J., Kawall, D., Kelton, L., Keshavarzi, A., Kessler, D. S., Khaw, K. S., Khechadoorian, Z., Khomutov, N. V., Kiburg, B., Kiburg, M., Kim, O., Kinnaird, N., Kraegeloh, E., Krylov, V. A., Kuchinskiy, N. A., Labe, K. R., LaBounty, J., Lancaster, M., Lee, S., Li, B., Li, D., Li, L., Logashenko, I., Campos, A. Lorente, Lu, Z., Lucà, A., Lukicov, G., Lusiani, A., Lyon, A. L., MacCoy, B., Madrak, R., Makino, K., Mastroianni, S., Miller, J. P., Miozzi, S., Mitra, B., Morgan, J. P., Morse, W. M., Mott, J., Nath, A., Ng, J. K., Nguyen, H., Oksuzian, Y., Omarov, Z., Osofsky, R., Park, S., Pauletta, G., Piacentino, G. M., Pilato, R. N., Pitts, K. T., Plaster, B., Počanić, D., Pohlman, N., Polly, C. C., Price, J., Quinn, B., Qureshi, M. U. H., Ramachandran, S., Ramberg, E., Reimann, R., Roberts, B. L., Rubin, D. L., Santi, L., Schlesier, C., Schreckenberger, A., Semertzidis, Y. K., Shemyakin, D., Sorbara, M., Stapleton, J., Still, D., Stöckinger, D., Stoughton, C., Stratakis, D., Swanson, H. E., Sweetmore, G., Sweigart, D. A., Syphers, M. J., Tarazona, D. A., Teubner, T., Tewsley-Booth, A. E., Tishchenko, V., Tran, N. H., Turner, W., Valetov, E., Vasilkova, D., Venanzoni, G., Volnykh, V. P., Walton, T., Weisskopf, A., Welty-Rieger, L., Winter, P., Wu, Y., Yu, B., Yucel, M., Zeng, Y., and Zhang, C.

Subjects
High Energy Physics - Experiment
Abstract

We present a new measurement of the positive muon magnetic anomaly, $a_\mu \equiv (g_\mu - 2)/2$, from the Fermilab Muon $g\!-\!2$ Experiment using data collected in 2019 and 2020. We have analyzed more than 4 times the number of positrons from muon decay than in our previous result from 2018 data. The systematic error is reduced by more than a factor of 2 due to better running conditions, a more stable beam, and improved knowledge of the magnetic field weighted by the muon distribution, $\tilde{\omega}'^{}_p$, and of the anomalous precession frequency corrected for beam dynamics effects, $\omega_a$. From the ratio $\omega_a / \tilde{\omega}'^{}_p$, together with precisely determined external parameters, we determine $a_\mu = 116\,592\,057(25) \times 10^{-11}$ (0.21 ppm). Combining this result with our previous result from the 2018 data, we obtain $a_\mu\text{(FNAL)} = 116\,592\,055(24) \times 10^{-11}$ (0.20 ppm). The new experimental world average is $a_\mu (\text{Exp}) = 116\,592\,059(22)\times 10^{-11}$ (0.19 ppm), which represents a factor of 2 improvement in precision., Comment: 8 pages, 3 figures

Published
2023
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6. A search for μ+→e+γ with the first dataset of the MEG II experiment

Author

Afanaciev, K., Baldini, A. M., Ban, S., Baranov, V., Benmansour, H., Biasotti, M., Boca, G., Cattaneo, P. W., Cavoto, G., Cei, F., Chiappini, M., Chiarello, G., Corvaglia, A., Cuna, F., Maso, G. Dal, De Bari, A., De Gerone, M., Barusso, L. Ferrari, Francesconi, M., Galli, L., Gallucci, G., Gatti, F., Gerritzen, L., Grancagnolo, F., Grandoni, E. G., Grassi, M., Grigoriev, D. N., Hildebrandt, M., Ieki, K., Ignatov, F., Ikeda, F., Iwamoto, T., Karpov, S., Kettle, P.-R., Khomutov, N., Kobayashi, S., Kolesnikov, A., Kravchuk, N., Krylov, V., Kuchinskiy, N., Kyle, W., Libeiro, T., Malyshev, V., Matsushita, A., Meucci, M., Mihara, S., Molzon, W., Mori, Toshinori, Nakao, M., Nicolò, D., Nishiguchi, H., Ochi, A., Ogawa, S., Onda, R., Ootani, W., Oya, A., Palo, D., Panareo, M., Papa, A., Pettinacci, V., Popov, A., Renga, F., Ritt, S., Rossella, M., Rozhdestvensky, A., Schwendimann, P., Shimada, K., Signorelli, G., Takahashi, M., Tassielli, G. F., Toyoda, K., Uchiyama, Y., Usami, M., Venturini, A., Vitali, B., Voena, C., Yamamoto, K., Yanai, K., Yonemoto, T., Yoshida, K., and Yudin, Yu. V.

Published
2024
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7. Measurement of the anomalous precession frequency of the muon in the Fermilab Muon g-2 experiment

Author

Albahri, T., Anastasi, A., Anisenkov, A., Badgley, K., Baeßler, S., Bailey, I., Baranov, V. A., Barlas-Yucel, E., Barrett, T., Basti, A., Bedeschi, F., Berz, M., Bhattacharya, M., Binney, H. P., Bloom, P., Bono, J., Bottalico, E., Bowcock, T., Cantatore, G., Carey, R. M., Casey, B. C. K., Cauz, D., Chakraborty, R., Chang, S. P., Chapelain, A., Charity, S., Chislett, R., Choi, J., Chu, Z., Chupp, T. E., Corrodi, S., Cotrozzi, L., Crnkovic, J. D., Dabagov, S., Debevec, P. T., Di Falco, S., Di Meo, P., Di Sciascio, G., Di Stefano, R., Driutti, A., Duginov, V. N., Eads, M., Esquivel, J., Farooq, M., Fatemi, R., Ferrari, C., Fertl, M., Fienberg, A. T., Fioretti, A., Flay, D., Frlež, E., Froemming, N. S., Fry, J., Gabbanini, C., Galati, M. D., Ganguly, S., Garcia, A., George, J., Gibbons, L. K., Gioiosa, A., Giovanetti, K. L., Girotti, P., Gohn, W., Gorringe, T., Grange, J., Grant, S., Gray, F., Haciomeroglu, S., Halewood-Leagas, T., Hampai, D., Han, F., Hempstead, J., Herrod, A. T., Hertzog, D. W., Hesketh, G., Hibbert, A., Hodge, Z., Holzbauer, J. L., Hong, K. W., Hong, R., Iacovacci, M., Incagli, M., Kammel, P., Kargiantoulakis, M., Karuza, M., Kaspar, J., Kawall, D., Kelton, L., Keshavarzi, A., Kessler, D., Khaw, K. S., Khechadoorian, Z., Khomutov, N. V., Kiburg, B., Kiburg, M., Kim, O., Kim, Y. I., King, B., Kinnaird, N., Kraegeloh, E., Kuchibhotla, A., Kuchinskiy, N. A., Labe, K. R., LaBounty, J., Lancaster, M., Lee, M. J., Lee, S., Leo, S., Li, B., Li, D., Li, L., Logashenko, I., Campos, A. Lorente, Lucà, A., Lukicov, G., Lusiani, A., Lyon, A. L., MacCoy, B., Madrak, R., Makino, K., Marignetti, F., Mastroianni, S., Miller, J. P., Miozzi, S., Morse, W. M., Mott, J., Nath, A., Nguyen, H., Osofsky, R., Park, S., Pauletta, G., Piacentino, G. M., Pilato, R. N., Pitts, K. T., Plaster, B., Počanić, D., Pohlman, N., Polly, C. C., Price, J., Quinn, B., Raha, N., Ramachandran, S., Ramberg, E., Ritchie, J. L., Roberts, B. L., Rubin, D. L., Santi, L., Schlesier, C., Schreckenberger, A., Semertzidis, Y. K., Shemyakin, D., Smith, M. W., Sorbara, M., Stöckinger, D., Stapleton, J., Stoughton, C., Stratakis, D., Stuttard, T., Swanson, H. E., Sweetmore, G., Sweigart, D. A., Syphers, M. J., Tarazona, D. A., Teubner, T., Tewsley-Booth, A. E., Thomson, K., Tishchenko, V., Tran, N. H., Turner, W., Valetov, E., Vasilkova, D., Venanzoni, G., Walton, T., Weisskopf, A., Welty-Rieger, L., Winter, P., Wolski, A., and Wu, W.

Subjects
High Energy Physics - Experiment, Nuclear Experiment
Abstract

The Muon g-2 Experiment at Fermi National Accelerator Laboratory (FNAL) has measured the muon anomalous precession frequency $\omega_a$ to an uncertainty of 434 parts per billion (ppb), statistical, and 56 ppb, systematic, with data collected in four storage ring configurations during its first physics run in 2018. When combined with a precision measurement of the magnetic field of the experiment's muon storage ring, the precession frequency measurement determines a muon magnetic anomaly of $a_{\mu}({\rm FNAL}) = 116\,592\,040(54) \times 10^{-11}$ (0.46 ppm). This article describes the multiple techniques employed in the reconstruction, analysis and fitting of the data to measure the precession frequency. It also presents the averaging of the results from the eleven separate determinations of \omega_a, and the systematic uncertainties on the result., Comment: 29 pages, 19 figures. Published in Physical Review D

Published
2021
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8. Magnetic Field Measurement and Analysis for the Muon g-2 Experiment at Fermilab

Author

Albahri, T., Anastasi, A., Badgley, K., Baeßler, S., Bailey, I., Baranov, V. A., Barlas-Yucel, E., Barrett, T., Bedeschi, F., Berz, M., Bhattacharya, M., Binney, H. P., Bloom, P., Bono, J., Bottalico, E., Bowcock, T., Cantatore, G., Carey, R. M., Casey, B. C. K., Cauz, D., Chakraborty, R., Chang, S. P., Chapelain, A., Charity, S., Chislett, R., Choi, J., Chu, Z., Chupp, T. E., Conway, A., Corrodi, S., Cotrozzi, L., Crnkovic, J. D., Dabagov, S., Debevec, P. T., Di Falco, S., Di Meo, P., Di Sciascio, G., Di Stefano, R., Driutti, A., Duginov, V. N., Eads, M., Esquivel, J., Farooq, M., Fatemi, R., Ferrari, C., Fertl, M., Fienberg, A. T., Fioretti, A., Flay, D., Froemming, N. S., Gabbanini, C., Galati, M. D., Ganguly, S., Garcia, A., George, J., Gibbons, L. K., Gioiosa, A., Giovanetti, K. L., Girotti, P., Gohn, W., Gorringe, T., Grange, J., Grant, S., Gray, F., Haciomeroglu, S., Halewood-Leagas, T., Hampai, D., Han, F., Hempstead, J., Herrod, A. T., Hertzog, D. W., Hesketh, G., Hibbert, A., Hodge, Z., Holzbauer, J. L., Hong, K. W., Hong, R., Iacovacci, M., Incagli, M., Kammel, P., Kargiantoulakis, M., Karuza, M., Kaspar, J., Kawall, D., Kelton, L., Keshavarzi, A., Kessler, D., Khaw, K. S., Khechadoorian, Z., Khomutov, N. V., Kiburg, B., Kiburg, M., Kim, O., Kim, Y. I., King, B., Kinnaird, N., Kraegeloh, E., Kuchinskiy, N. A., Labe, K. R., LaBounty, J., Lancaster, M., Lee, M. J., Lee, S., Li, B., Li, D., Li, L., Logashenko, I., Campos, A. Lorente, Lucà, A., Lukicov, G., Lusiani, A., Lyon, A. L., MacCoy, B., Madrak, R., Makino, K., Marignetti, F., Mastroianni, S., Miller, J. P., Miozzi, S., Morse, W. M., Mott, J., Nath, A., Nguyen, H., Osofsky, R., Park, S., Pauletta, G., Piacentino, G. M., Pilato, R. N., Pitts, K. T., Plaster, B., Počanić, D., Pohlman, N., Polly, C. C., Price, J., Quinn, B., Raha, N., Ramachandran, S., Ramberg, E., Ritchie, J. L., Roberts, B. L., Rubin, D. L., Santi, L., Schlesier, C., Schreckenberger, A., Semertzidis, Y. K., Shemyakin, D., Smith, M. W., Sorbara, M., Stöckinger, D., Stapleton, J., Stoughton, C., Stratakis, D., Stuttard, T., Swanson, H. E., Sweetmore, G., Sweigart, D. A., Syphers, M. J., Tarazona, D. A., Teubner, T., Tewsley-Booth, A. E., Thomson, K., Tishchenko, V., Tran, N. H., Turner, W., Valetov, E., Vasilkova, D., Venanzoni, G., Walton, T., Weisskopf, A., Welty-Rieger, L., Winter, P., Wolski, A., and Wu, W.

Subjects
High Energy Physics - Experiment, Nuclear Experiment
Abstract

The Fermi National Accelerator Laboratory has measured the anomalous precession frequency $a^{}_\mu = (g^{}_\mu-2)/2$ of the muon to a combined precision of 0.46 parts per million with data collected during its first physics run in 2018. This paper documents the measurement of the magnetic field in the muon storage ring. The magnetic field is monitored by nuclear magnetic resonance systems and calibrated in terms of the equivalent proton spin precession frequency in a spherical water sample at 34.7$^\circ$C. The measured field is weighted by the muon distribution resulting in $\tilde{\omega}'^{}_p$, the denominator in the ratio $\omega^{}_a$/$\tilde{\omega}'^{}_p$ that together with known fundamental constants yields $a^{}_\mu$. The reported uncertainty on $\tilde{\omega}'^{}_p$ for the Run-1 data set is 114 ppb consisting of uncertainty contributions from frequency extraction, calibration, mapping, tracking, and averaging of 56 ppb, and contributions from fast transient fields of 99 ppb., Comment: Added one citation and corrected missing normalization in Eqs (35) and (36)

Published
2021
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9. Measurement of the Positive Muon Anomalous Magnetic Moment to 0.46 ppm

Author

Abi, B., Albahri, T., Al-Kilani, S., Allspach, D., Alonzi, L. P., Anastasi, A., Anisenkov, A., Azfar, F., Badgley, K., Baeßler, S., Bailey, I., Baranov, V. A., Barlas-Yucel, E., Barrett, T., Barzi, E., Basti, A., Bedeschi, F., Behnke, A., Berz, M., Bhattacharya, M., Binney, H. P., Bjorkquist, R., Bloom, P., Bono, J., Bottalico, E., Bowcock, T., Boyden, D., Cantatore, G., Carey, R. M., Carroll, J., Casey, B. C. K., Cauz, D., Ceravolo, S., Chakraborty, R., Chang, S. P., Chapelain, A., Chappa, S., Charity, S., Chislett, R., Choi, J., Chu, Z., Chupp, T. E., Convery, M. E., Conway, A., Corradi, G., Corrodi, S., Cotrozzi, L., Crnkovic, J. D., Dabagov, S., De Lurgio, P. M., Debevec, P. T., Di Falco, S., Di Meo, P., Di Sciascio, G., Di Stefano, R., Drendel, B., Driutti, A., Duginov, V. N., Eads, M., Eggert, N., Epps, A., Esquivel, J., Farooq, M., Fatemi, R., Ferrari, C., Fertl, M., Fiedler, A., Fienberg, A. T., Fioretti, A., Flay, D., Foster, S. B., Friedsam, H., Frlež, E., Froemming, N. S., Fry, J., Fu, C., Gabbanini, C., Galati, M. D., Ganguly, S., Garcia, A., Gastler, D. E., George, J., Gibbons, L. K., Gioiosa, A., Giovanetti, K. L., Girotti, P., Gohn, W., Gorringe, T., Grange, J., Grant, S., Gray, F., Haciomeroglu, S., Hahn, D., Halewood-Leagas, T., Hampai, D., Han, F., Hazen, E., Hempstead, J., Henry, S., Herrod, A. T., Hertzog, D. W., Hesketh, G., Hibbert, A., Hodge, Z., Holzbauer, J. L., Hong, K. W., Hong, R., Iacovacci, M., Incagli, M., Johnstone, C., Johnstone, J. A., Kammel, P., Kargiantoulakis, M., Karuza, M., Kaspar, J., Kawall, D., Kelton, L., Keshavarzi, A., Kessler, D., Khaw, K. S., Khechadoorian, Z., Khomutov, N. V., Kiburg, B., Kiburg, M., Kim, O., Kim, S. C., Kim, Y. I., King, B., Kinnaird, N., Korostelev, M., Kourbanis, I., Kraegeloh, E., Krylov, V. A., Kuchibhotla, A., Kuchinskiy, N. A., Labe, K. R., LaBounty, J., Lancaster, M., Lee, M. J., Lee, S., Leo, S., Li, B., Li, D., Li, L., Logashenko, I., Campos, A. Lorente, Lucà, A., Lukicov, G., Luo, G., Lusiani, A., Lyon, A. L., MacCoy, B., Madrak, R., Makino, K., Marignetti, F., Mastroianni, S., Maxfield, S., McEvoy, M., Merritt, W., Mikhailichenko, A. A., Miller, J. P., Miozzi, S., Morgan, J. P., Morse, W. M., Mott, J., Motuk, E., Nath, A., Newton, D., Nguyen, H., Oberling, M., Osofsky, R., Ostiguy, J. -F., Park, S., Pauletta, G., Piacentino, G. M., Pilato, R. N., Pitts, K. T., Plaster, B., Počanić, D., Pohlman, N., Polly, C. C., Popovic, M., Price, J., Quinn, B., Raha, N., Ramachandran, S., Ramberg, E., Rider, N. T., Ritchie, J. L., Roberts, B. L., Rubin, D. L., Santi, L., Sathyan, D., Schellman, H., Schlesier, C., Schreckenberger, A., Semertzidis, Y. K., Shatunov, Y. M., Shemyakin, D., Shenk, M., Sim, D., Smith, M. W., Smith, A., Soha, A. K., Sorbara, M., Stöckinger, D., Stapleton, J., Still, D., Stoughton, C., Stratakis, D., Strohman, C., Stuttard, T., Swanson, H. E., Sweetmore, G., Sweigart, D. A., Syphers, M. J., Tarazona, D. A., Teubner, T., Tewsley-Booth, A. E., Thomson, K., Tishchenko, V., Tran, N. H., Turner, W., Valetov, E., Vasilkova, D., Venanzoni, G., Volnykh, V. P., Walton, T., Warren, M., Weisskopf, A., Welty-Rieger, L., Whitley, M., Winter, P., Wolski, A., Wormald, M., Wu, W., and Yoshikawa, C.

Subjects
High Energy Physics - Experiment, Nuclear Experiment
Abstract

We present the first results of the Fermilab Muon g-2 Experiment for the positive muon magnetic anomaly $a_\mu \equiv (g_\mu-2)/2$. The anomaly is determined from the precision measurements of two angular frequencies. Intensity variation of high-energy positrons from muon decays directly encodes the difference frequency $\omega_a$ between the spin-precession and cyclotron frequencies for polarized muons in a magnetic storage ring. The storage ring magnetic field is measured using nuclear magnetic resonance probes calibrated in terms of the equivalent proton spin precession frequency ${\tilde{\omega}'^{}_p}$ in a spherical water sample at 34.7$^{\circ}$C. The ratio $\omega_a / {\tilde{\omega}'^{}_p}$, together with known fundamental constants, determines $a_\mu({\rm FNAL}) = 116\,592\,040(54)\times 10^{-11}$ (0.46\,ppm). The result is 3.3 standard deviations greater than the standard model prediction and is in excellent agreement with the previous Brookhaven National Laboratory (BNL) E821 measurement. After combination with previous measurements of both $\mu^+$ and $\mu^-$, the new experimental average of $a_\mu({\rm Exp}) = 116\,592\,061(41)\times 10^{-11}$ (0.35\,ppm) increases the tension between experiment and theory to 4.2 standard deviations, Comment: 10 pages; 4 figures

Published
2021
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10. Beam dynamics corrections to the Run-1 measurement of the muon anomalous magnetic moment at Fermilab

Author

Albahri, T., Anastasi, A., Badgley, K., Baeßler, S., Bailey, I., Baranov, V. A., Barlas-Yucel, E., Barrett, T., Bedeschi, F., Berz, M., Bhattacharya, M., Binney, H. P., Bloom, P., Bono, J., Bottalico, E., Bowcock, T., Cantatore, G., Carey, R. M., Casey, B. C. K., Cauz, D., Chakraborty, R., Chang, S. P., Chapelain, A., Charity, S., Chislett, R., Choi, J., Chu, Z., Chupp, T. E., Corrodi, S., Cotrozzi, L., Crnkovic, J. D., Dabagov, S., Debevec, P. T., Di Falco, S., Di Meo, P., Di Sciascio, G., Di Stefano, R., Driutti, A., Duginov, V. N., Eads, M., Esquivel, J., Farooq, M., Fatemi, R., Ferrari, C., Fertl, M., Fiedler, A., Fienberg, A. T., Fioretti, A., Flay, D., Frlež, E., Froemming, N. S., Fry, J., Gabbanini, C., Galati, M. D., Ganguly, S., Garcia, A., George, J., Gibbons, L. K., Gioiosa, A., Giovanetti, K. L., Girotti, P., Gohn, W., Gorringe, T., Grange, J., Grant, S., Gray, F., Haciomeroglu, S., Halewood-Leagas, T., Hampai, D., Han, F., Hempstead, J., Herrod, A. T., Hertzog, D. W., Hesketh, G., Hibbert, A., Hodge, Z., Holzbauer, J. L., Hong, K. W., Hong, R., Iacovacci, M., Incagli, M., Kammel, P., Kargiantoulakis, M., Karuza, M., Kaspar, J., Kawall, D., Kelton, L., Keshavarzi, A., Kessler, D., Khaw, K. S., Khechadoorian, Z., Khomutov, N. V., Kiburg, B., Kiburg, M., Kim, O., Kim, Y. I., King, B., Kinnaird, N., Korostelev, M., Kraegeloh, E., Kuchinskiy, N. A., Labe, K. R., LaBounty, J., Lancaster, M., Lee, M. J., Lee, S., Li, B., Li, D., Li, L., Logashenko, I., Campos, A. Lorente, Lucà, A., Lukicov, G., Lusiani, A., Lyon, A. L., MacCoy, B., Madrak, R., Makino, K., Marignetti, F., Mastroianni, S., Miller, J. P., Miozzi, S., Morse, W. M., Mott, J., Nath, A., Newton, D., Nguyen, H., Osofsky, R., Park, S., Pauletta, G., Piacentino, G. M., Pilato, R. N., Pitts, K. T., Plaster, B., Počanić, D., Pohlman, N., Polly, C. C., Price, J., Quinn, B., Raha, N., Ramachandran, S., Ramberg, E., Ritchie, J. L., Roberts, B. L., Rubin, D. L., Santi, L., Sathyan, D., Schlesier, C., Schreckenberger, A., Semertzidis, Y. K., Smith, M. W., Sorbara, M., Stöckinger, D., Stapleton, J., Stoughton, C., Stratakis, D., Stuttard, T., Swanson, H. E., Sweetmore, G., Sweigart, D. A., Syphers, M. J., Tarazona, D. A., Teubner, T., Tewsley-Booth, A. E., Thomson, K., Tishchenko, V., Tran, N. H., Turner, W., Valetov, E., Vasilkova, D., Venanzoni, G., Walton, T., Weisskopf, A., Welty-Rieger, L., Winter, P., Wolski, A., and Wu, W.

Subjects
Physics - Accelerator Physics, High Energy Physics - Experiment
Abstract

This paper presents the beam dynamics systematic corrections and their uncertainties for the Run-1 data set of the Fermilab Muon g-2 Experiment. Two corrections to the measured muon precession frequency $\omega_a^m$ are associated with well-known effects owing to the use of electrostatic quadrupole (ESQ) vertical focusing in the storage ring. An average vertically oriented motional magnetic field is felt by relativistic muons passing transversely through the radial electric field components created by the ESQ system. The correction depends on the stored momentum distribution and the tunes of the ring, which has relatively weak vertical focusing. Vertical betatron motions imply that the muons do not orbit the ring in a plane exactly orthogonal to the vertical magnetic field direction. A correction is necessary to account for an average pitch angle associated with their trajectories. A third small correction is necessary because muons that escape the ring during the storage time are slightly biased in initial spin phase compared to the parent distribution. Finally, because two high-voltage resistors in the ESQ network had longer than designed RC time constants, the vertical and horizontal centroids and envelopes of the stored muon beam drifted slightly, but coherently, during each storage ring fill. This led to the discovery of an important phase-acceptance relationship that requires a correction. The sum of the corrections to $\omega_a^m$ is 0.50 $\pm$ 0.09 ppm; the uncertainty is small compared to the 0.43 ppm statistical precision of $\omega_a^m$., Comment: 35 pages, 29 figures. Accepted by Phys. Rev. Accel. Beams

Published
2021
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11. Beam particle tracking with a low-mass mini time projection chamber in the PEN experiment

Author

Glaser, C. J., Pocanic, D., van der Schaaf, A., Baranov, V. A., Khomutov, N. V., Kravchuk, N. P., and Kuchinsky, N. A.

Subjects
Physics - Instrumentation and Detectors, High Energy Physics - Experiment, High Energy Physics - Phenomenology, Nuclear Experiment
Abstract

The international PEN collaboration aims to obtain the branching ratio for the pion electronic decay $\pi^+ \to e^+\nu_e(\gamma)$, aka $\pi_{e2}$, to a relative precision of $5\times 10^{-4}$ or better. The PEN apparatus comprises a number of detection systems, all contributing vital information to the PEN event reconstruction. This paper discusses the design, performance, and Monte Carlo simulation of the mini time projection chamber (mTPC) used for pion, muon, and positron beam particle tracking. We also review the use of the extracted trajectory coordinates in the analysis, in particular in constructing observables critical for discriminating background processes, and in maximizing the fiducial volume of the target in which decay event vertices can be accepted for branching ratio extraction without introducing bias., Comment: 24 pages, 23 figures

Published
2020
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12. Search for lepton flavour violating muon decay mediated by a new light particle in the MEG experiment

Author

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
High Energy Physics - Experiment
Abstract

We present the first direct search for lepton flavour violating muon decay mediated by a new light particle X, $\mu^+ \to \mathrm{e}^+\mathrm{X}, \mathrm{X} \to \gamma\gamma$. This search uses a dataset resulting from $7.5\times 10^{14}$ 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$^2$ for lifetimes below 40 ps, and we set the most stringent branching ratio upper limits in the mass region of 20--40 MeV/c$^2$, down to $\mathcal{O}(10^{-11})$ at 90\% confidence level.

Published
2020
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14. PEN experiment: a precise test of lepton universality

Author

Glaser, C. J., Pocanic, D., Alonzi, L. P., Baranov, V. A., Bertl, W., Bychkov, M., Bystritsky, Yu. M., Frlez, E., Kalinnikov, V. A., Khomutov, N. V., Korenchenko, A. S., Korenchenko, S. M., Korolija, M., Kozlowski, T., Kravchuk, N. P., Kuchinsky, N. A., Lehman, M. C., Munyangabe, E., Mzhavia, D., Palladino, A., Robmann, P., Rozhdestvensky, A. M., Smith, R. T., Supek, I., Truöl, P., van der Schaaf, A., Velicheva, E. P., Vitz, M. G., and Volnykh, V. P.

Subjects
High Energy Physics - Experiment, High Energy Physics - Phenomenology, Nuclear Experiment
Abstract

With few open channels and uncomplicated theoretical description, charged pion decays are uniquely sensitive to certain standard model (SM) symmetries, the universality of weak fermion couplings, and to aspects of pion structure and chiral dynamics. We review the current knowledge of the pion electronic decay $\pi^+ \to e^+ \nu_e({\gamma})$, or $\pi_{e2({\gamma})}$, and the resulting limits on non-SM processes. Focusing on the PEN experiment at the Paul Scherrer Institute (PSI), Switzerland, we examine the prospects for further improvement in the near term., Comment: Talk presented at CIPANP2018. 9 pages, LaTeX, 4 pdf figures, 1 table. arXiv admin note: substantial text overlap with arXiv:1701.05254

Published
2018

15. The design of the MEG II experiment

Author

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., Nicoló, 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
Physics - Instrumentation and Detectors, High Energy Physics - Experiment
Abstract

The MEG experiment, designed to search for the mu+->e+ gamma decay at a 10^-13 sensitivity level, completed data taking in 2013. In order to increase the sensitivity reach of the experiment by an order of magnitude to the level of 6 x 10-14 for the branching ratio, 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., Comment: 61 pages and 97 figures

Published
2018
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16. PEN: a low energy test of lepton universality

Author

Pocanic, D., Alonzi, L. P., Baranov, V. A., Bertl, W., Bychkov, M., Bystritsky, Yu. M., Frlez, E., Glaser, C. J., Kalinnikov, V. A., Khomutov, N. V., Korenchenko, A. S., Korenchenko, S. M., Korolija, M., Kozlowski, T., Kravchuk, N. P., Kuchinsky, N. A., Lehman, M. C., Mzhavia, D., Palladino, A., Robmann, P., Rozhdestvensky, A. M., Supek, I., Truoel, P., van der Schaaf, A., Velicheva, E. P., Vitz, M. G., and Volnykh, V. P.

Subjects
High Energy Physics - Experiment, High Energy Physics - Phenomenology, Nuclear Experiment
Abstract

Allowed charged $\pi$ meson decays are characterized by simple dynamics, few available decay channels, mainly into leptons, and extremely well controlled radiative and loop corrections. In that sense, pion decays represent a veritable triumph of the standard model (SM) of elementary particles and interactions. This relative theoretical simplicity makes charged pion decays a sensitive means for testing the underlying symmetries and the universality of weak fermion couplings, as well as for studying pion structure and chiral dynamics. Even after considerable recent improvements, experimental precision is lagging far behind that of the theoretical description for pion decays. We review the current state of experimental study of the pion electronic decay $\pi^+ \to e^+\nu_e(\gamma)$, or $\pi_{e2(\gamma)}$, where the $(\gamma)$ indicates inclusion and explicit treatment of radiative decay events. We briefly review the limits on non-SM processes arising from the present level of experimental precision in $\pi_{e2(\gamma)}$ decays. Focusing on the PEN experiment at the Paul Scherrer Institute (PSI), Switzerland, we examine the prospects for further improvement in the near term., Comment: 11 pages, 5 figures; paper presented at the XIII International Conference on Heavy Quarks and Leptons, 22-27 May 2016, Blacksburg, Virginia, USA

Published
2017

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

Author

Baldini, A. M., Bao, Y., Baracchini, E., Bemporad, C., Berg, F., Biasotti, M., Boca, G., Cattaneo, P. W., Cavoto, G., Cei, F., Chiarello, G., Chiri, C., De Bari, A., De Gerone, M., DÓnofrio, 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, T. I., Kettle, P. R., Khazin, B. I., Khomutov, N., Korenchenko, A., Kravchuk, N., Lim, G. M. A., Mihara, S., Molzon, W., Mori, T., Mtchedlishvili, A., Nakaura, S., Nicolò, D., Nishiguchi, H., Nishimura, M., Ogawa, S., Ootani, W., Panareo, M., Papa, A., Pepino, A., Piredda, G., Pizzigoni, G., Popov, A., Renga, F., Ripiccini, E., Ritt, S., Rossella, M., Rutar, G., Sawada, R., Sergiampietri, F., Signorelli, G., Tassielli, G., Tenchini, F., Uchiyama, Y., Venturini, M., Voena, C., Yamamoto, A., Yoshida, K., You, Z., and Yudin, Y. V.

Subjects
High Energy Physics - Experiment, Physics - Instrumentation and Detectors
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
2015
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18. 2-D straw detectors with high rate capability

Author

Kuchinskiy, N. A., Baranov, V. A., Duginov, V. N., Zyazyulya, F. E., Korenchenko, A. S., Kolesnikov, A. O., Kravchuk, N. P., Movchan, S. A., Rudenko, A. I., Smirnov, V. S., Khomutov, N. V., Chekhovsky, V. A., Lobko, A. S., and Misevich, O. V.

Subjects
Physics - Instrumentation and Detectors, High Energy Physics - Experiment
Abstract

Precise measurement of straw axial coordinate (along the anode wire) with accuracy compatible with straw radial coordinate determination by drift time measurement and increase of straw detector rate capability by using straw cathode readout instead of anode readout are presented., Comment: 16 pages, 10 figures

Published
2015

19. Muon (g-2) Technical Design Report

Author

Grange, J., Guarino, V., Winter, P., Wood, K., Zhao, H., Carey, R. M., Gastler, D., Hazen, E., Kinnaird, N., Miller, J. P., Mott, J., Roberts, B. L., Benante, J., Crnkovic, J., Morse, W. M., Sayed, H., Tishchenko, V., Druzhinin, V. P., Khazin, B. I., Koop, I. A., Logashenko, I., Shatunov, Y. M., Solodov, E., Korostelev, M., Newton, D., Wolski, A., Chapelain, A., Bjorkquist, R., Eggert, N., Frankenthal, A., Gibbons, L., Kim, S., Mikhailichenko, A., Orlov, Y., Rubin, D., Sweigart, D., Allspach, D., Annala, G., Barzi, E., Bourland, K., Brown, G., Casey, B. C. K., Chappa, S., Convery, M. E., Drendel, B., Friedsam, H., Gadfort, T., Hardin, K., Hawke, S., Hayes, S., Jaskierny, W., Johnstone, C., Johnstone, J., Kashikhin, V., Kendziora, C., Kiburg, B., Klebaner, A., Kourbanis, I., Kyle, J., Larson, N., Leveling, A., Lyon, A. L., Markley, D., McArthur, D., Merritt, K. W., Mokhov, N., Morgan, J. P., Nguyen, H., Ostiguy, J-F., Para, A., Popovic, C. C. Polly M., Ramberg, E., Rominsky, M., Schoo, D., Schultz, R., Still, D., Soha, A. K., Strigonov, S., Tassotto, G., Turrioni, D., Villegas, E., Voirin, E., Velev, G., Welty-Rieger, L., Wolff, D., Worel, C., Wu, J-Y., Zifko, R., Jungmann, K., Onderwater, C. J. G., Debevec, P. T., Ganguly, S., Kasten, M., Leo, S., Pitts, K., Schlesier, C., Gaisser, M., Haciomeroglu, S., Kim, Y-I., Lee, S., Lee, M-J, Semertzidis, Y. K., Giovanetti, K., Baranov, V. A., Duginov, V. N., Khomutov, N. V., Krylov, V. A., Kuchinskiy, N. A., Volnykh, V. P., Crawford, C., Fatemi, R., Gohn, W. P., Gorringe, T. P., Korsch, W., Plaster, B., Anastasi, A., Babusci, D., Dabagov, S., Ferrari, C., Fioretti, A., Gabbanini, C., Hampai, D., Palladino, A., Venanzoni, G., Bowcock, T., Carroll, J., King, B., Maxfield, S., McCormick, K., Price, J., Sim, D., Smith, A., Teubner, T., Turner, W., Whitley, M., Wormald, M., Chislett, R., Kilani, S., Lancaster, M., Motuk, E., Stuttard, T., Warren, M., Flay, D., Kawall, D., Meadows, Z., Chupp, T., Raymond, R., Tewlsey-Booth, A., Syphers, M. J., Tarazona, D., Catalonotti, S., Di Stefano, R., Iacovacci, M., Mastroianni, S., Chattopadhyay, S., Eads, M., Fortner, M., Hedin, D., Pohlman, N., de Gouvea, A., Schellman, H., Azfar, F., Henry, S., Alkhazov, G. D., Golovtsov, V. L., Neustroev, P. V., Uvarov, L. N., Vasilyev, A. A., Vorobyov, A. A., Zhalov, M. B., Cerrito, L., Gray, F., Di Sciascio, G., Moricciani, D., Fu, C., Ji, X., Li, L., Yang, H., Stöckinger, D., Cantatore, G., Cauz, D., Karuza, M., Pauletta, G., Santi, L., Baeßler, S., Bychkov, M., Frlez, E., Pocanic, D., Alonzi, L. P., Fertl, M., Fienberg, A., Froemming, N., Garcia, A., Kaspar, D. W. Hertzog J., Kammel, P., Osofsky, R., Smith, M., Swanson, E., van Wechel, T., and Lynch, K.

Subjects
Physics - Instrumentation and Detectors, High Energy Physics - Experiment
Abstract

The Muon (g-2) Experiment, E989 at Fermilab, will measure the muon anomalous magnetic moment a factor-of-four more precisely than was done in E821 at the Brookhaven National Laboratory AGS. The E821 result appears to be greater than the Standard-Model prediction by more than three standard deviations. When combined with expected improvement in the Standard-Model hadronic contributions, E989 should be able to determine definitively whether or not the E821 result is evidence for physics beyond the Standard Model. After a review of the physics motivation and the basic technique, which will use the muon storage ring built at BNL and now relocated to Fermilab, the design of the new experiment is presented. This document was created in partial fulfillment of the requirements necessary to obtain DOE CD-2/3 approval., Comment: 666 pages

Published
2015

20. New results in rare allowed muon and pion decays

Author

Pocanic, D., Munyangabe, E., Bychkov, M., Baranov, V. A., Bertl, W., Bystritsky, Yu. M., Frlez, E., Kalinnikov, V. A., Khomutov, N. V., Korenchenko, A. S., Korenchenko, S. M., Korolija, M., Kozlowski, T., Kravchuk, N. P., Kuchinsky, N. A., Lehman, M. C., Mekterovic, D., Mzhavia, D., Palladino, A., Robmann, P., Rozhdestvensky, A. M., Supek, I., Truoel, P., Tsamalaidze, Z., van der Schaaf, A., Vandevender, B., Velicheva, E. P., and Volnykh, V. P.

Subjects
Nuclear Experiment, High Energy Physics - Experiment, High Energy Physics - Phenomenology
Abstract

Simple dynamics, few available decay channels, and highly controlled radiative and loop corrections, make pion and muon decays a sensitive means of exploring details of the underlying symmetries. We review the current status of the rare decays: pi+ -> e+ nu, pi+ -> e+ nu gamma, pi+ -> pi0 e+ nu, and mu+ -> e+ nu nu-bar gamma. For the latter we report new preliminary values for the branching ratio B(E_gamma >10 MeV, theta_(e-gamma) > 30deg) = 4.365 (9)_stat (42)_syst x 10^{-3}, and the decay parameter eta-bar = 0.006 (17)_stat (18)_syst, both in excellent agreement with standard model predictions. We review recent measurements, particularly by the PIBETA and PEN experiments, and near-term prospects for improvement. These and other similar precise low energy studies complement modern collider results materially., Comment: 5 pages, 2 figures, talk presented at the 9th International Workshop on e+ e- Collisions "From phi to psi 2013", held in Rome, 9-12 Sept 2013

Published
2014
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21. Measurement of the radiative decay of polarized muons in the MEG experiment

Author

MEG Collaboration, Baldini, A. M., Bao, Y., Baracchini, E., Bemporad, C., Berg, F., Biasotti, M., Boca, G., Cattaneo, P. W., Cavoto, G., Cei, F., Chiarello, G., Chiri, C., 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, M., Papa, A., Pepino, A., Piredda, G., Pizzigoni, G., Popov, A., Renga, F., Ripiccini, E., Ritt, S., Rossella, M., Rutar, G., Sawada, R., Sergiampietri, F., Signorelli, G., Tassielli, G. F., Tenchini, F., Uchiyama, Y., Venturini, M., Voena, C., Yamamoto, A., Yoshida, K., You, Z., and Yudin, Yu. V.

Subjects
High Energy Physics - Experiment, High Energy Physics - Phenomenology, Physics - Instrumentation and Detectors
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

Published
2013
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22. The use of segmented cathode of a drift tube for designing a track detector with a high rate capability

Author

Kuchinskiy, N. A., Baranov, V. A., Duginov, V. N., Zyazyulya, F. E., Korenchenko, A. S., Kolesnikov, A. O., Kravchuk, N. P., Movchan, S. A., Rudenko, A. I., Smirnov, V. S., Khomutov, N. V., and Chekhovsky, V. A.

Subjects
Physics - Instrumentation and Detectors, High Energy Physics - Experiment
Abstract

Detector rate capability is one of the main parameters for designing a new detector for high energy physics due to permanent rise of the beam luminosity of modern accelerators. One of the widely used detectors for particle track reconstruction is a straw detector based on drift tubes. The rate capability of such detectors is limited by the parameters of readout electronics. The traditional method of increasing detector rate capability is increasing their granularity (a number of readout channels) by reducing the straw diameter and/or by dividing the straw anode wire into two parts (for decreasing the rate per readout channel). A new method of designing straw detectors with a high rate capability is presented and tested. The method is based on dividing the straw cathode into parts and independent readout of each part., Comment: 10 pages, 8 figures

Published
2013

23. MEG Upgrade Proposal

Author

Baldini, A. M., Cei, F., Cerri, C., Dussoni, S., Galli, L., Grassi, M., Nicolò, D., Raffaelli, F., Sergiampietri, F., Signorelli, G., Tenchini, F., Bagliani, D., De Gerone, M., Gatti, F., Baracchini, E., Fujii, Y., Iwamoto, T., Kaneko, D., Mori, T., Nishimura, M., Ootani, W., Sawada, R., Uchiyama, Y., Boca, G., Cattaneo, P. W., de Bari, A., Nardò, R., Rossella, M., Cascella, M., Grancagnolo, F., L'Erario, A., Maffezzoli, A., Miccoli, A., Onorato, G., Palamà, G., Panareo, M., Pepino, A., Rella, S., Tassielli, G. F., Zavarise, G., Cavoto, G., Graziosi, A., Piredda, G., Ripiccini, E., Voena, C., Grigoriev, D. N., Ignatov, F., Khazin, B. I., Popov, A., Yudin, Yu. V., Haruyama, T., Mihara, S., Nishiguchi, H., Yamamoto, A., Hildebrandt, M., Kettle, P. -R., Papa, A., Renga, F., Ritt, S., Stoykov, A., Kang, T. I., Lim, G., Molzon, W., You, Z., Khomutov, N., Korenchenko, A., Kravchuk, N., and Kuchinksy, N.

Subjects
Physics - Instrumentation and Detectors, High Energy Physics - Experiment, High Energy Physics - Phenomenology
Abstract

We propose the continuation of the MEG experiment to search for the charged lepton flavour violating decay (cLFV) \mu \to e \gamma, based on an upgrade of the experiment, which aims for a sensitivity enhancement of one order of magnitude compared to the final MEG result, down to the $6 \times 10^{-14}$ level. The key features of this new MEG upgrade are an increased rate capability of all detectors to enable running at the intensity frontier and improved energy, angular and timing resolutions, for both the positron and photon arms of the detector. On the positron-side a new low-mass, single volume, high granularity tracker is envisaged, in combination with a new highly segmented, fast timing counter array, to track positron from a thinner stopping target. The photon-arm, with the largest liquid xenon (LXe) detector in the world, totalling 900 l, will also be improved by increasing the granularity at the incident face, by replacing the current photomultiplier tubes (PMTs) with a larger number of smaller photosensors and optimizing the photosensor layout also on the lateral faces. A new DAQ scheme involving the implementation of a new combined readout board capable of integrating the diverse functions of digitization, trigger capability and splitter functionality into one condensed unit, is also under development. We describe here the status of the MEG experiment, the scientific merits of the upgrade and the experimental methods we plan to use., Comment: A. M. Baldini and T. Mori Spokespersons. Research proposal submitted to the Paul Scherrer Institute Research Committee for Particle Physics at the Ring Cyclotron. 131 Pages

Published
2013

24. New studies of allowed pion and muon decays

Author

Pocanic, D., Palladino, A., Alonzi, L. P., Baranov, V. A., Bertl, W., Bychkov, M., Bystritsky, Yu. M., Frlez, E., Kalinnikov, V. A., Khomutov, N. V., Korenchenko, A. S., Korenchenko, S. M., Korolija, M., Kozlowski, T., Kravchuk, N. P., Kuchinsky, N. A., Lehman, M. C., Mekterovic, D., Munyangabe, E., Mzhavia, D., Robmann, P., Rozhdestvensky, A. M., Shkarovskiy, S. N., Straumann, U., Supek, I., Truöl, P., Tsamalaidze, Z., van der Schaaf, A., Velicheva, E. P., and Volnykh, V. P.

Subjects
High Energy Physics - Experiment, Nuclear Experiment
Abstract

Building on the rare pion and muon decay results of the PIBETA experiment, the PEN collaboration has undertaken a precise measurement of B_{\pi e2} = R^\pi_{e/\mu}, the \pi^+ -> e^+\nu(\gamma) decay branching ratio, at the Paul Scherrer Institute, to reduce the present 40\times experimental precision lag behind theory to ~ 6-7\times. Because of large helicity suppression, R^\pi_{e/\mu} is uniquely sensitive to contributions from non-(V-A) physics, making this decay a particularly suitable subject of study. Even at current precision, the experimental value of B_{\pi e2} provides the most accurate test of lepton universality available. During runs in 2008-10, PEN has accumulated over 2\times 10^7 \pi_{e2} events; a comprehensive maximum-likelihood analysis is currently under way. The new data will also lead to improved precision of the earlier PIBETA results on radiative \pi and \mu decays., Comment: 3 pages, 3 figures, to appear in Proceedings, 11th Conference on the Intersections of Particle and Nuclear Physics (CIPANP 2012), held at St. Petersburg, Florida, 29 May - 3 June 2012

Published
2012
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25. Detector with a profile-based cathode and a two-coordinate pad-strip readout system

Author

Kuchinskiy, N. A., Baturitskii, V. A., Kravchuk, N. P., Korenchenko, A. S., Khomutov, N. V., Smirnov, V. S., Chekhovskii, V. A., Movchan, S. A., and Zyazyulya, F. E.

Subjects
Physics - Instrumentation and Detectors, High Energy Physics - Experiment
Abstract

A detector with a profile-based cathode and a pad-strip cathode readout system is experimentally investigated. Cathode pads arranged along each anode wire are diagonally interconnected and form strips that cross the detector at an angle with respect to the anode wire. Two coordinates from the cathodes and one from the anode wire allow identification of tracks in high multiplicity events with a single detector plane., Comment: 6 pages, 5 figures

Published
2011

26. Using the cathode surface of straw tube for measuring the track coordinates along the wire

Author

Baranov, V. A., Chekhovskiy, B. A., Kravchuk, N. P., Korenchenko, A. S., Kuchinskiy, N. A., Khomutov, N. V., Movchan, S. A., Smirnov, V. S., and Zyazyulya, F. E.

Subjects
Physics - Instrumentation and Detectors
Abstract

The coordinate detectors based on straw tubes provide a high accuracy of the radial coordinate measurement using the drift time and a small amount of matter in the way of the measured particles. However, the measurement of the coordinate along the wire constitutes a problem. This paper proposes a method for measuring the hit coordinate along the wire with an accuracy better than 1 mm in a straw tube detector using the signals from the cathodes of the detector., Comment: 5 pages, 5 figures, submitted to Instrum. Exper. Tech.(Pribory i Tekhnika Eksperimenta)

Published
2011

27. Testing isotropy of the universe using the Ramsey resonance technique on ultracold neutron spins

Author

Altarev, I., Ban, G., Bison, G., Bodek, K., Daum, M., Fertl, M., Fierlinger, P., Franke, B., Gutsmiedl, E., Heil, W., Henneck, R., Horras, M., Khomutov, N., Kirch, K., Kistryn, S., Kraft, A., Knecht, A., Knowles, P., Kozela, A., Lauer, T., Lauss, B., Lefort, T., Lemière, Y., Mtchedlishvili, A., Naviliat-Cuncic, O., Pazgalev, A., Petzoldt, G., Piegsa, F. M., Pierre, E., Pignol, G., Quéméner, G., Rebetez, M., Rebreyend, D., Roccia, S., Schmidt-Wellenburg, P., Severijns, N., Sobolev, Yu., Weis, A., Zejma, J., Zenner, J., and Zsigmond, G.

Subjects
Physics - Atomic Physics, High Energy Physics - Experiment, Nuclear Experiment
Abstract

Physics at the Planck scale could be revealed by looking for tiny violations of fundamental symmetries in low energy experiments. In 2008, a sensitive test of the isotropy of the Universe using has been performed with stored ultracold neutrons (UCN), this is the first clock-comparison experiment performed with free neutrons. During several days we monitored the Larmor frequency of neutron spins in a weak magnetic field using the Ramsey resonance technique. An non-zero cosmic axial field, violating rotational symmetry, would induce a daily variation of the precession frequency. Our null result constitutes one of the most stringent tests of Lorentz invariance to date., Comment: proceedings of the PNCMI2010 conference

Published
2010
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28. New constraints on Lorentz invariance violation from the neutron electric dipole moment

Author

Altarev, I., Baker, C. A., Ban, G., Bodek, K., Daum, M., Fertl, M., Franke, B., Fierlinger, P., Geltenbort, P., Green, K., van der Grinten, M. G. D., Harris, P. G., Henneck, R., Horras, M., Iaydjiev, P., Ivanov, S. N., Khomutov, N., Kirch, K., Kistryn, S., Knecht, A., Kozela, A., Kuchler, F., Lauss, B., Lefort, T., Lemière, Y., Mtchedlishvili, A., Naviliat-Cuncic, O., Pendlebury, J. M., Petzoldt, G., Pierre, E., Piegsa, F. M., Pignol, G., Quéméner, G., Rebreyend, D., Roccia, S., Schmidt-Wellenburg, P., Severijns, N., Shiers, D., Smith, K. F., Sobolev, Yu., Zejma, J., Zenner, J., and Zsigmond, G.

Subjects
Nuclear Experiment
Abstract

We propose an original test of Lorentz invariance in the interaction between a particle spin and an electromagnetic field and report on a first measurement using ultracold neutrons. We used a high sensitivity neutron electric dipole moment (nEDM) spectrometer and searched for a direction dependence of a nEDM signal leading to a modulation of its magnitude at periods of 12 and 24 hours. We constrain such a modulation to $d_{12} < 15 \times 10^{-25} \ e\,{\rm cm}$ and $d_{24} < 10 \times 10^{-25} \ e\,{\rm cm}$ at 95~\% C.L. The result translates into a limit on the energy scale for this type of Lorentz violation effect at the level of ${\cal E}_{LV} > 10^{10}$~GeV., Comment: Submitted to Phys. Rev. Lett

Published
2010
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29. PEN: a sensitive search for non-(V-A) weak processes

Author

PEN Collaboration, Pocanic, D., Alonzi, L. P., Baranov, V. A., Bertl, W., Bychkov, M., Bystritsky, Yu. M., Frlez, E., Kalinnikov, V. A., Khomutov, N. V., Korenchenko, A. S., Korenchenko, S. M., Korolija, M., Kozlowski, T., Kravchuk, N. P., Kuchinsky, N. A., Mekterovic, D., Mzhavia, D., Palladino, A., Robmann, P., Rozhdestvensky, A. M., Shkarovskiy, S. N., Straumann, U., Supek, I., Truoel, P., Tsamalaidze, Z., van der Schaaf, A., Velicheva, E. P., and Volnykh, V. P.

Subjects
High Energy Physics - Experiment
Abstract

A new measurement of $B_{\pi e2}$, the $\pi^+ \to e^+\nu(\gamma)$ decay branching ratio, is currently under way at the Paul Scherrer Institute. The present experimental result on $B_{\pi e2}$ constitutes the most accurate test of lepton universality available. The accuracy, however, still lags behind the theoretical precision by over an order of magnitude. Thanks to the large helicity suppression of $\pi_{e2}$ decay, the branching ratio is susceptible to significant contributions from new physics, making this decay a particularly suitable subject of study., Comment: 4 pages, 1 figure, talk given at the 18th International Conference on Particles and Nuclei (PANIC08), held 9 -14 November 2008 in Eilat, Israel; to appear in the Proceedings published by North Holland

Published
2009

30. PEN experiment: a precise measurement of the pi+ -> e+ nu decay branching fraction

Author

PEN Collaboration, Pocanic, D., Alonzi, L. P., Baranov, V. A., Bertl, W., Bychkov, M., Bystritsky, Yu. M., Frlez, E., Kalinnikov, V. A., Khomutov, N. V., Korenchenko, A. S., Korenchenko, S. M., Korolija, M., Kozlowski, T., Kravchuk, N. P., Kuchinsky, N. A., Mekterovic, D., Mzhavia, D., Palladino, A., Robmann, P., Rozhdestvensky, A. M., Shkarovskiy, S. N., Straumann, U., Supek, I., Truoel, P., Tsamalaidze, Z., van der Schaaf, A., Velicheva, E. P., and Volnykh, V. P.

Subjects
High Energy Physics - Experiment
Abstract

A new measurement of $B_{\pi e2}$, the $\pi^+ \to e^+\nu(\gamma)$ decay branching ratio, is currently under way at the Paul Scherrer Institute. The present experimental result on $B_{\pi e2}$ constitutes the most accurate test of lepton universality available. The accuracy, however, still lags behind the theoretical precision by over an order of magnitude. Because of the large helicity suppression of the $\pi_{e2}$ decay, its branching ratio is susceptible to significant contributions from new physics, making this decay a particularly suitable subject of study., Comment: 4 pages, 3 figures, talk given at the Tenth Conference on the Intersections of Particle and Nuclear Physics (CIPANP 2009), La Jolla/San Diego, CA, 26-31 May 2009; to appear in Proceedings to be published by the American Institute of Physics

Published
2009
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31. Neutron to Mirror-Neutron Oscillations in the Presence of Mirror Magnetic Fields

Author

Altarev, I., Baker, C. A., Ban, G., Bodek, K., Daum, M., Fierlinger, P., Geltenbort, P., Green, K., van der Grinten, M. G. D., Gutsmiedl, E., Harris, P. G., Henneck, R., Horras, M., Iaydjiev, P., Ivanov, S., Khomutov, N., Kirch, K., Kistryn, S., Knecht, A., Knowles, P., Kozela, A., Kuchler, F., Kuźniak, M., Lauer, T., Lauss, B., Lefort, T., Mtchedlishvili, A., Naviliat-Cuncic, O., Paul, S., Pazgalev, A., Pendlebury, J. M., Petzoldt, G., Pierre, E., Plonka-Spehr, C., Quéméner, G., Rebreyend, D., Roccia, S., Rogel, G., Severijns, N., Shiers, D., Sobolev, Yu., Stoepler, R., Weis, A., Zejma, J., Zenner, J., and Zsigmond, G.

Subjects
Nuclear Experiment
Abstract

We performed ultracold neutron (UCN) storage measurements to search for additional losses due to neutron (n) to mirror-neutron (n') oscillations as a function of an applied magnetic field B. In the presence of a mirror magnetic field B', UCN losses would be maximal for B = B'. We did not observe any indication for nn' oscillations and placed a lower limit on the oscillation time of tau_{nn'} > 12.0 s at 95% C.L. for any B' between 0 and 12.5 uT., Comment: 4 pages, 2 figures. Accepted for publication in Phys. Rev. D

Published
2009
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32. Test of Lorentz invariance with spin precession of ultracold neutrons

Author

Altarev, I., Baker, C. A., Ban, G., Bison, G., Bodek, K., Daum, M., Fierlinger, P., Geltenbort, P., Green, K., van der Grinten, M. G. D., Gutsmiedl, E., Harris, P. G., Heil, W., Henneck, R., Horras, M., Iaydjiev, P., Ivanov, S. N., Khomutov, N., Kirch, K., Kistryn, S., Knecht, A., Knowles, P., Kozela, A., Kuchler, F., Kuźniak, M., Lauer, T., Lauss, B., Lefort, T., Mtchedlishvili, A., Naviliat-Cuncic, O., Pazgalev, A., Pendlebury, J. M., Petzoldt, G., Pierre, E., Pignol, G., Quéméner, G., Rebetez, M., Rebreyend, D., Roccia, S., Rogel, G., Severijns, N., Shiers, D., Sobolev, Yu., Weis, A., Zejma, J., and Zsigmond, G.

Subjects
Nuclear Experiment
Abstract

A clock comparison experiment, analyzing the ratio of spin precession frequencies of stored ultracold neutrons and $^{199}$Hg atoms is reported. %57 No daily variation of this ratio could be found, from which is set an upper limit on the Lorentz invariance violating cosmic anisotropy field $b_{\bot} < 2 \times 10^{-20} {\rm eV}$ (95% C.L.). This is the first limit for the free neutron. This result is also interpreted as a direct limit on the gravitational dipole moment of the neutron $|g_n| < 0.3 $eV/$c^2$ m from a spin-dependent interaction with the Sun. Analyzing the gravitational interaction with the Earth, based on previous data, yields a more stringent limit $|g_n| < 3 \times 10^{-4} $eV/$c^2 $m., Comment: 4 pages, 3 figures accepted for publication in Phys. Rev. Lett

Published
2009
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33. Precise Measurement of pi+ -> e+ nu Branching Ratio

Author

Frlež, E., Alonzi, L. P., Baranov, V. A., Bertl, W., Bychkov, M., Bystritsky, Yu. M., Khomutov, N. V., Korenchenko, A. S., Korenchenko, S. M., Korolija, M., Kozlowski, T., Kravchuk, N. P., Kuchinsky, N. A., Mekterović, D., Mzhavia, D., Palladino, A., Počanić, D., Robmann, P., Rozhdestvensky, A. M., Sidorkin, V. V., Straumann, U., Supek, I., Truöl, P., van der Schaaf, A., Velicheva, E. P., and Volnykh, V. P.

Subjects
High Energy Physics - Experiment
Abstract

The PEN Collaboration is conducting a new measurement of the pi+ -> e+ nu branching ratio at the Paul Scherrer Institute, with the goal uncertainty of delta B/B(pie2)=5E-4 or lower. At present, the combined accuracy of all published pie2 decay measurements lags behind the theoretical calculation by a factor of 40. In this contribution we report on the PEN detector configuration and its performance during two development runs done in 2007 and 2008., Comment: pdflatex, 11 pages, 5 figures, to be published in "Progress in High-Energy Physics and Nuclear Safety", NATO Science for Peace Series: B - Physics and Biophysics

Published
2008
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34. An Improved Neutron Electric Dipole Moment Experiment

Author

Kuźniak, M., Altarev, I., Ban, G., Bison, G., Bodek, K., Burghoff, M., Daum, M., Eberhardt, K., Fierlinger, P., Gutsmiedl, E., Hampel, G., Heil, W., Henneck, R., Khomutov, N., Kirch, K., Kistryn, St., Knappe-Grueneberg, S., Knecht, A., Knowles, P., Kratz, J. V., Lauer, T., Lauss, B., Lefort, T., Mtchedlishvili, A., Naviliat-Cuncic, O., Paul, S., Pazgalev, A. S., Petzold, G., Plonka-Spehr, C., Quéméner, G., Rebreyend, D., Roccia, S., Rogel, G., Sander-Thoemmes, T., Schnabel, A., Severijns, N., Sobolev, Yu., Stoepler, R., Trahms, L., Tur, M., Weis, A., Wiehl, N., Zejma, J., and Zsigmond, G.

Subjects
Nuclear Experiment
Abstract

A new measurement of the neutron EDM, using Ramsey's method of separated oscillatory fields, is in preparation at the new high intensity source of ultra-cold neutrons (UCN) at the Paul Scherrer Institute, Villigen, Switzerland (PSI). The existence of a non-zero nEDM would violate both parity and time reversal symmetry and, given the CPT theorem, might lead to a discovery of new CP violating mechanisms. Already the current upper limit for the nEDM (|d_n|<2.9E-26 e.cm) constrains some extensions of the Standard Model. The new experiment aims at a two orders of magnitude reduction of the experimental uncertainty, to be achieved mainly by (1) the higher UCN flux provided by the new PSI source, (2) better magnetic field control with improved magnetometry and (3) a double chamber configuration with opposite electric field directions. The first stage of the experiment will use an upgrade of the RAL/Sussex/ILL group's apparatus (which has produced the current best result) moved from Institut Laue-Langevin to PSI. The final accuracy will be achieved in a further step with a new spectrometer, presently in the design phase., Comment: Flavor Physics & CP Violation Conference, Taipei, 2008

Published
2008

35. New Precise Measurement of the Pion Weak Form Factors in the Pi+ -> e+ nu gamma Decay

Author

Bychkov, M., Počanić, D., VanDevender, B. A., Baranov, V. A., Bertl, W., Bystritsky, Yu. M., Frlež, E., Kalinnikov, V. A., Khomutov, N. V., Korenchenko, A. S., Korenchenko, S. M., Korolija, M., Kozlowski, T., Kravchuk, N. P., Kuchinsky, N. A., Li, W., Mekterović, D., Mzhavia, D., Ritt, S., Robmann, P., Rondon-Aramayo, O. A., Rozhdestvensky, A. M., Sakhelashvili, T., Scheu, S., Straumann, U., Supek, I., Tsamalaidze, Z., van der Schaaf, A., Velicheva, E. P., Volnykh, V. P., Wang, Y., and Wirtz, H. -P.

Subjects
High Energy Physics - Experiment, High Energy Physics - Phenomenology, Nuclear Experiment
Abstract

We have measured the $\pi^+\to {\rm e}^+\nu\gamma$ branching ratio over a wide region of phase space, based on a total of 65,460 events acquired using the PIBETA detector. Minimum-$\chi^2$ fits to the measured $(E_{e^+},E_\gamma)$ energy distributions result in the weak form factor value of $F_A=0.0119(1)$ with a fixed value of $F_V=0.0259$. An unconstrained fit yields $F_V=0.0258(17)$ and $F_A=0.0117(17)$. In addition, we have measured $a=0.10(6)$ for the dependence of $F_V$ on $q^2$, the ${\rm e}^{+}\nu$ pair invariant mass squared, parametrized as $F_V(q^2)=F_V(0)(1+a\cdot q^2)$. The branching ratio for the kinematic region $E_\gamma > 10 $MeV and $\theta_{{\rm e^+}\gamma} > 40^\circ $ is measured to be $B^{\rm exp}=73.86(54) \times 10^{-8}$. Earlier deviations we reported in the high-$E_\gamma$/low-$E_{{\rm e}^+}$ kinematic region are resolved, and we find full compatibility with CVC and standard $V$$-$$A$ calculations without a tensor term. We also derive new values for the pion polarizability, $\alpha_E = \rm 2.78(10) \times 10^{-4} fm^3$, and neutral pion lifetime, $\tau_{\pi 0} = (8.5 \pm 1.1) \times 10^{-17} $s., Comment: 4 pages, 2 PDF figures

Published
2008
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36. A direct experimental limit on neutron -- mirror neutron oscillations

Author

Ban, G., Bodek, K., Daum, M., Henneck, R., Heule, S., Kasprzak, M., Khomutov, N., Kirch, K., Kistryn, S., Knecht, A., Knowles, P., Kuzniak, M., Lefort, T., Mtchedlishvili, A., Naviliat-Cuncic, O., Plonka, C., Quemener, G., Rebetez, M., Rebreyend, D., Roccia, S., Rogel, G., Tur, M., Weis, A., Zejma, J., and Zsigmond, G.

Subjects
Nuclear Experiment
Abstract

In case a mirror world with a copy of our ordinary particle spectrum would exist, the neutron n and its degenerate partner, the mirror neutron ${\rm n'}$, could potentially mix and undergo ${\rm nn'}$ oscillations. The interaction of an ordinary magnetic field with the ordinary neutron would lift the degeneracy between the mirror partners, diminish the ${\rm n'}$-amplitude in the n-wavefunction and, thus, suppress its observability. We report an experimental comparison of ultracold neutron storage in a trap with and without superimposed magnetic field. No influence of the magnetic field is found and, assuming negligible mirror magnetic fields, a limit on the oscillation time $\tau_{\rm nn'} > 103$ s (95% C.L.) is derived., Comment: 4 pages, 1 figure. accepted for publication in Phys. Rev. Lett

Published
2007
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37. Precise Measurement of the Pi+ -> Pi0 e+ nu Branching Ratio

Author

Pocanic, D., Frlez, E., Baranov, V. A., Bertl, W., Broennimann, C., Bychkov, M., Crawford, J. F., Daum, M., Khomutov, N. V., Korenchenko, A. S., Korenchenko, S. M., Kozlowski, T., Kravchuk, N. P., Kuchinsky, N. A., Li, W., Minehart, R. C., Mzhavia, D., Ritchie, B. G., Ritt, S., Rozhdestvensky, A. M., Sidorkin, V. V., Smith, L. C., Supek, I., Tsamalaidze, Z., VanDevender, B. A., Wang, Y., Wirtz, H. -P., and Ziock, K. O. H.

Subjects
High Energy Physics - Experiment
Abstract

Using a large acceptance calorimeter and a stopped pion beam we have made a precise measurement of the rare Pi+ -> Pi0 e+ Nu,(pi_beta) decay branching ratio. We have evaluated the branching ratio by normalizing the number of observed pi_beta decays to the number of observed Pi+ -> e+ Nu, (pi_{e2}) decays. We find the value of Gamma(Pi+ -> Pi0 e+ Nu)/Gamma(total) = [1.036 +/- 0.004(stat.) +/- 0.004(syst.) +/- 0.003(pi_{e2})] x 10^{-8}$, where the first uncertainty is statistical, the second systematic, and the third is the pi_{e2} branching ratio uncertainty. Our result agrees well with the Standard Model prediction., Comment: 4 pages, 5 figures, 1 table, revtex4; changed content; updated analysis

Published
2003
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38. Precise Measurement of the Pion Axial Form Factor in the Pi+ -> e+ nu gamma Decay

Author

Frlez, E., Pocanic, D., Baranov, V. A., Bertl, W., Bychkov, M., Khomutov, N. V., Korenchenko, A. S., Korenchenko, S. M., Kozlowski, T., Kravchuk, N. P., Kuchinsky, N. A., Li, W., Minehart, R. C., Mzhavia, D., Ritchie, B. G., Ritt, S., Rozhdestvensky, A. M., Sidorkin, V. V., Smith, L. C., Supek, I., Tsamalaidze, Z., VanDevender, B. A., Velicheva, E. P., Wang, Y., Wirtz, H. -P., and Ziock, K. O. H.

Subjects
High Energy Physics - Experiment
Abstract

We have studied radiative pion decays Pi+ -> e+ nu gamma in three broad kinematic regions using the PIBETA detector and a stopped pion beam. Based on Dalitz distributions of 42,209 events we have evaluated absolute Pi -> e nu gamma branching ratios in the three regions. Minimum chi^2 fits to the integral and differential (E(e+),E(gamma)) distributions result in the axial-to-vector weak form factor ratio of gamma = F_A/F_V = 0.443(15),or F_A = 0.0115(4) with F_V = 0.0259. However, deviations from Standard Model predictions in the high-E(gamma)/low-E(e+) kinematic region indicate the need for further theoretical and experimental work., Comment: 5 pages, 4 figures, 1 table, revtex4

Published
2003
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39. Design, Commissioning and Performance of the PIBETA Detector at PSI

Author

Frlez, E., Pocanic, D., Assamagan, K. A., Bagaturia, Yu., Baranov, V. A., Bertl, W., Broennimann, Ch., Bychkov, M. A., Crawford, J. F., Daum, M., Fluegel, Th., Frosch, R., Horisberger, R., Kalinnikov, V. A., Karpukhin, V. V., Khomutov, N. V., Koglin, J. E., Korenchenko, A. S., Korenchenko, S. M., Kozlowski, T., Krause, B., Kravchuk, N. P., Kuchinsky, N. A., Li, W., Lawrence, D. W., Minehart, R. C., Mzhavia, D., Obermeier, H., Renker, D., Ritchie, B. G., Ritt, S., Sakhelashvili, T., Schnyder, R., Sidorkin, V. V., Slocum, P. L., Smith, L. C., Soic, N., Stephens, W. A., Supek, I., Tsamalaidze, Z., VanDevender, B. A., Wang, Y., Wirtz, H. -P., and Ziock, K. O. H.

Subjects
High Energy Physics - Experiment, Physics - Instrumentation and Detectors
Abstract

We describe the design, construction and performance of the PIBETA detector built for the precise measurement of the branching ratio of pion beta decay, pi+ -> pi0 e+ nu, at the Paul Scherrer Institute. The central part of the detector is a 240-module spherical pure CsI calorimeter covering 3*pi sr solid angle. The calorimeter is supplemented with an active collimator/beam degrader system, an active segmented plastic target, a pair of low-mass cylindrical wire chambers and a 20-element cylindrical plastic scintillator hodoscope. The whole detector system is housed inside a temperature-controlled lead brick enclosure which in turn is lined with cosmic muon plastic veto counters. Commissioning and calibration data were taken during two three-month beam periods in 1999/2000 with pi+ stopping rates between 1.3*E3 pi+/s and 1.3*E6 pi+/s. We examine the timing, energy and angular detector resolution for photons, positrons and protons in the energy range of 5-150 MeV, as well as the response of the detector to cosmic muons. We illustrate the detector signatures for the assorted rare pion and muon decays and their associated backgrounds., Comment: 117 pages, 48 Postscript figures, 5 tables, Elsevier LaTeX, submitted to Nucl. Instrum. Meth. A

Published
2003
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40. Search for NN-decoupled dibaryons using the process $pp \to \gamma \gamma X$ below the pion production threshold

Author

Khrykin, A. S., Boreiko, V. F., Budyashov, Yu. G., Gerasimov, S. B., Khomutov, N. V., Sobolev, Yu. G., and Zorin, V. P.

Subjects
Nuclear Experiment, High Energy Physics - Phenomenology, Nuclear Theory
Abstract

The energy spectrum for high energy $\gamma$-rays ($E_\gamma \geq 10$ MeV) from the process $pp \to \gamma \gamma X$ emitted at $90^0$ in the laboratory frame has been measured at an energy below the pion production threshold, namely, at 216 MeV. The resulting photon energy spectrum extracted from $\gamma-\gamma$ coincidence events consists of a narrow peak at a photon energy of about 24 MeV and a relatively broad peak in the energy range of (50 - 70) MeV. The statistical significances for the narrow and broad peaks are 5.3$\sigma$ and 3.5$\sigma$, respectively. This behavior of the photon energy spectrum is interpreted as a signature of the exotic dibaryon resonance $d^\star_1$ with a mass of about 1956 MeV which is assumed to be formed in the radiative process $pp \to \gamma d^\star_1$ followed by its electromagnetic decay via the $d^\star_1 \to pp \gamma$ mode. The experimental spectrum is compared with those obtained by means of Monte Carlo simulations., Comment: 14 pages, LaTex, 6 eps-figures, accepted for publication in Phys.Rev.C

Published
2000
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41. Investigation of Rare Pion Decays with the PIBETA Spectrometer

Author

Počanić, D., Alonzi, L. P., Baranov, V. A., Bertl, W., Bystritsky, Yu. M., Bychkov, M. A., Velicheva, E. P., Vol’nykh, V. P., Kalinnikov, V. A., Kozlowski, T., Korenchenko, A. S., Korenchenko, S. M., Korolija, M., Kravchuk, N. P., Kuchinsky, N. A., Lehman, M., Mzhavia, D. A., Palladino, A., Robmann, P., Rozhdestvensky, A. M., Rondon-Aramayo, O. A., Supek, I., Truöl, P., Frlež, E., Khomutov, N. V., Tsamalaidze, Z., and van der Schaaf, A.

Published
2018
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42. A Tracker Prototype Based on Cathode Straw Tubes

Author

Baranov, V. A., Bosak, N. A., Botay, L. E., Duginov, V. N., Zyazyulya, F. E., Kolesnikov, A. O., Korenchenko, A. S., Kravchuk, N. P., Kuchinskiy, N. A., Lobko, A. S., Misevich, O. V., Movchan, S. A., Smirnov, V. S., Khomutov, N. V., and Chekhovsky, V. A.

Published
2018
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44. 2-D straw detectors with high rate capability

Author

Kuchinskiy, N. A., Baranov, V. A., Duginov, V. N., Zyazyulya, F. E., Korenchenko, A. S., Kolesnikov, A. O., Kravchuk, N. P., Movchan, S. A., Rudenko, A. I., Smirnov, V. S., Khomutov, N. V., Chekhovsky, V. A., Lobko, A. S., and Misevich, O. V.

Published
2017
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45. Precise Measurement of the π+ → e + v Branching Ratio

Author

Frlež, E., Alonzi, L. P., Baranov, V. A., Bertl, W., Bychkov, M., Bystritsky, Yu. M., Khomutov, N. V., Korenchenko, A. S., Korenchenko, S. M., Korolija, M., Kozlowski, T., Kravchuk, N. P., Kuchinsky, N. A., Mekterović, D., Mzhavia, D., Palladino, A., Počanić, D., Robmann, P., Rozhdestvensky, A. M., Sidorkin, V. V., Straumann, U., Supek, I., Truöl, P., Schaaf, A. van der, Velicheva, E. P., Volnykh, V. V., Begun, Viktor, editor, Jenkovszky, László L., editor, and Polański, Aleksander, editor

Published
2009
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46. Search for the lepton flavour violating decay μ + → e + γ with the full dataset of the MEG experiment: MEG Collaboration

Author

Baldini, A. M., Bao, Y., Baracchini, E., Bemporad, C., Berg, F., Biasotti, M., Boca, G., Cascella, M., Cattaneo, P. W., Cavoto, G., Cei, F., Cerri, C., Chiarello, G., Chiri, C., Corvaglia, A., de Bari, A., De Gerone, M., Doke, T., D’Onofrio, A., Dussoni, S., Egger, J., 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, T. I., Kettle, P.-R., Khazin, B. I., Khomutov, N., Korenchenko, A., Kravchuk, N., Lim, G. M. A., Maki, A., Mihara, S., Molzon, W., Mori, Toshinori, Morsani, F., Mtchedilishvili, A., Mzavia, D., Nakaura, S., Nardò, R., Nicolò, D., Nishiguchi, H., Nishimura, M., Ogawa, S., Ootani, W., Orito, S., Panareo, M., Papa, A., Pazzi, R., Pepino, A., Piredda, G., Pizzigoni, G., Popov, A., Raffaelli, F., Renga, F., Ripiccini, E., Ritt, S., Rossella, M., Rutar, G., Sawada, R., Sergiampietri, F., Signorelli, G., Simonetta, M., Tassielli, G. F., Tenchini, F., Uchiyama, Y., Venturini, M., Voena, C., Yamamoto, A., Yoshida, K., You, Z., Yudin, Yu. V., and Zanello, D.

Published
2016
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47. Muon polarization in the MEG experiment: predictions and measurements: The MEG Collaboration

Author

Baldini, A. M., Bao, Y., Baracchini, E., Bemporad, C., Berg, F., Biasotti, M., Boca, G., Cattaneo, P. W., Cavoto, G., Cei, F., Chiarello, G., Chiri, C., Bari, A. De, Gerone, M. De, 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, T. I., 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, M., Papa, A., Pepino, A., Piredda, G., Pizzigoni, G., Popov, A., Renga, F., Ripiccini, E., Ritt, S., Rossella, M., Rutar, G., Sawada, R., Sergiampietri, F., Signorelli, G., Tassielli, G. F., Tenchini, F., Uchiyama, Y., Venturini, M., Voena, C., Yamamoto, A., Yoshida, K., You, Z., and Yudin, Yu. V.

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

Author

Baldini, A. M., Bao, Y., Baracchini, E., Bemporad, C., Berg, F., Biasotti, M., Boca, G., Cattaneo, P. W., Cavoto, G., Cei, F., Chiarello, G., Chiri, C., 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, M., Papa, A., Pepino, A., Piredda, G., Pizzigoni, G., Popov, A., Renga, F., Ripiccini, E., Ritt, S., Rossella, M., Rutar, G., Sawada, R., Sergiampietri, F., Signorelli, G., Tassielli, G. F., Tenchini, F., Uchiyama, Y., Venturini, M., Voena, C., Yamamoto, A., Yoshida, K., You, Z., Yudin, Yu. V., and The MEG Collaboration

Published
2016
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