K. Tshoo, Y. Satou, H. Bhang, S. Choi, T. Nakamura, Y. Kondo, S. Deguchi, Y. Kawada, N. Kobayashi, Y. Nakayama, K. N. Tanaka, N. Tanaka, N. Aoi, M. Ishihara, T. Motobayashi, H. Otsu, H. Sakurai, S. Takeuchi, Y. Togano, K. Yoneda, Z. H. Li, F. Delaunay, J. Gibelin, F. M. Marqués, N. A. Orr, T. Honda, M. Matsushita, T. Kobayashi, Y. Miyashita, T. Sumikama, K. Yoshinaga, S. Shimoura, D. Sohler, T. Zheng, Z. X. Cao
The unbound excited states of the neutron drip-line isotope 24O have been investigated via the 24O(p,p')23O+n reaction in inverse kinematics at a beam energy of 62 MeV/nucleon. The decay energy spectrum of 24O* was reconstructed from the momenta of 23O and the neutron. The spin-parity of the first excited state, observed at Ex = 4.65 +/- 0.14 MeV, was determined to be Jpi = 2+ from the angular distribution of the cross section. Higher lying states were also observed. The quadrupole transition parameter beta2 of the 2+ state was deduced, for the first time, to be 0.15 +/- 0.04. The relatively high excitation energy and small beta2 value are indicative of the N = 16 shell closure in 24O.
T. Abu-Zayyad, R. Aida, M. Allen, R. Anderson, R. Azuma, E. Barcikowski, J. W. Belz, D. R. Bergman, S. A. Blake, R. Cady, B. G. Cheon, J. Chiba, M. Chikawa, E. J. Cho, W. R. Cho, H. Fujii, T. Fujii, T. Fukuda, M. Fukushima, D. Gorbunov, W. Hanlon, K. Hayashi, Y. Hayashi, N. Hayashida, K. Hibino, K. Hiyama, K. Honda, T. Iguchi, D. Ikeda, K. Ikuta, N. Inoue, T. Ishii, R. Ishimori, D. Ivanov, S. Iwamoto, C. C. H. Jui, K. Kadota, F. Kakimoto, O. Kalashev, T. Kanbe, K. Kasahara, H. Kawai, S. Kawakami, S. Kawana, E. Kido, H. B. Kim, H. K. Kim, J. H. Kim, J. H. Kim, K. Kitamoto, S. Kitamura, Y. Kitamura, K. Kobayashi, Y. Kobayashi, Y. Kondo, K. Kuramoto, V. Kuzmin, Y. J. Kwon, J. Lan, S. I. Lim, S. Machida, K. Martens, T. Matsuda, T. Matsuura, T. Matsuyama, J. N. Matthews, M. Minamino, K. Miyata, Y. Murano, I. Myers, K. Nagasawa, S. Nagataki, T. Nakamura, S. W. Nam, T. Nonaka, S. Ogio, M. Ohnishi, H. Ohoka, K. Oki, D. Oku, T. Okuda, A. Oshima, S. Ozawa, I. H. Park, M. S. Pshirkov, D. C. Rodriguez, S. Y. Roh, G. I. Rubtsov, D. Ryu, H. Sagawa, N. Sakurai, A. L. Sampson, L. M. Scott, P. D. Shah, F. Shibata, T. Shibata, H. Shimodaira, B. K. Shin, J. I. Shin, T. Shirahama, J. D. Smith, P. Sokolsky, B. T. Stokes, S. R. Stratton, T. Stroman, S. Suzuki, Y. Takahashi, M. Takeda, A. Taketa, M. Takita, Y. Tameda, H. Tanaka, K. Tanaka, M. Tanaka, S. B. Thomas, G. B. Thomson, P. Tinyakov, I. Tkachev, H. Tokuno, T. Tomida, S. Troitsky, Y. Tsunesada, K. Tsutsumi, Y. Tsuyuguchi, Y. Uchihori, S. Udo, H. Ukai, G. Vasiloff, Y. Wada, T. Wong, M. Wood, Y. Yamakawa, R. Yamane, H. Yamaoka, K. Yamazaki, J. Yang, Y. Yoneda, S. Yoshida, H. Yoshii, X. Zhou, R. Zollinger, Z. Zundel
Apr 20, 2013·astro-ph.HE·PDF We search for ultra-high energy photons by analyzing geometrical properties of shower fronts of events registered by the Telescope Array surface detector. By making use of an event-by-event statistical method, we derive upper limits on the absolute flux of primary photons with energies above 10^19, 10^19.5 and 10^20 eV based on the first three years of data taken.
Z. H. Yang, Y. Kubota, A. Corsi, K. Yoshida, X. -X. Sun, J. G. Li, M. Kimura, N. Michel, K. Ogata, C. X. Yuan, Q. Yuan, G. Authelet, H. Baba, C. Caesar, D. Calvet, A. Delbart, M. Dozono, J. Feng, F. Flavigny, J. -M. Gheller, J. Gibelin, A. Giganon, A. Gillibert, K. Hasegawa, T. Isobe, Y. Kanaya, S. Kawakami, D. Kim, Y. Kiyokawa, M. Kobayashi, N. Kobayashi, T. Kobayashi, Y. Kondo, Z. Korkulu, S. Koyama, V. Lapoux, Y. Maeda, F. M. Marqes, T. Motobayashi, T. Miyazaki, T. Nakamura, N. Nakatsuka, Y. Nishio, A. Obertelli, y A. Ohkura, N. A. Orr, S. Ota, H. Otsu, T. Ozaki, V. Panin, S. Paschalis, E. C. Pollacco, S. Reichert, J. -Y. Rousse, A. T. Saito, S. Sakaguchi, M. Sako, C. Santamaria, 4 M. Sasano, H. Sato, M. Shikata, Y. Shimizu, Y. Shindo, L. Stuhl, T. Sumikama, Y. L. Sun, M. Tabata, Y. Togano, J. Tsubota, F. R. Xu, J. Yasuda, K. Yoneda, J. Zenihiro, S. -G. Zhou, W. Zuo, T. Uesaka
A kinematically complete quasi-free $(p,pn)$ experiment in inverse kinematics was performed to study the structure of the Borromean nucleus $^{17}$B, which had long been considered to have neutron halo. By analyzing the momentum distributions and exclusive cross sections, we obtained the spectroscopic factors for $1s_{1/2}$ and $0d_{5/2}$ orbitals, and a surprisingly small percentage of 9(2)$\%$ was determined for $1s_{1/2}$. Our finding of such a small $1s_{1/2}$ component and the halo features reported in prior experiments can be explained by the deformed relativistic Hartree-Bogoliubov theory in continuum, revealing a definite but not dominant neutron halo in $^{17}$B. The present work gives the smallest $s$- or $p$-orbital component among known nuclei exhibiting halo features, and implies that the dominant occupation of $s$ or $p$ orbitals is not a prerequisite for the occurrence of neutron halo.
S. Bae, H. Choi, S. Choi, Y. Fukao, K. Futatsukawa, K. Hasegawa, T. Iijima, H. Iinuma, K. Ishida, N. Kawamura, B. Kim, R. Kitamura, H. S. Ko, Y. Kondo, S. Li, T. Mibe, Y. Miyake, T. Morishita, Y. Nakazawa, M. Otani, G. P. Razuvaev, N. Saito, K. Shimomura, Y. Sue, E. Won, T. Yamazaki
Muons have been accelerated by using a radio frequency accelerator for the first time. Negative muonium atoms (Mu$^-$), which are bound states of positive muons ($μ^+$) and two electrons, are generated from $μ^+$'s through the electron capture process in an aluminum degrader. The generated Mu$^-$'s are initially electrostatically accelerated and injected into a radio frequency quadrupole linac (RFQ). In the RFQ, the Mu$^-$'s are accelerated to 89 keV. The accelerated Mu$^-$'s are identified by momentum measurement and time of flight. This compact muon linac opens the door to various muon accelerator applications including particle physics measurements and the construction of a transmission muon microscope.
J. Gibelin, D. Beaumel, T. Motobayashi, N. Aoi, H. Baba, Y. Blumenfeld, Z. Elekes, S. Fortier, N. Frascaria, N. Fukuda, T. Gomi, K. Ishikawa, Y. Kondo, T. Kubo, V. Lima, T. Nakamura, A. Saito, Y. Satou, E. Takeshita, S. Takeuchi, T. Teranishi, Y. Togano, A. M. Vinodkumar, Y. Yanagisawa, K. Yoshida
Coulomb excitation of the exotic neutron-rich nucleus $^{26}$Ne on a $^{nat}$Pb target was measured at 58 A.MeV in order to search for low-lying E1 strength above the neutron emission threshold. Data were also taken on an $^{nat}$Al target to estimate the nuclear contribution. The radioactive beam was produced by fragmentation of a 95 A.MeV $^{40}$Ar beam delivered by the RIKEN Research Facility. The set-up included a NaI gamma-ray array, a charged fragment hodoscope and a neutron wall. Using the invariant mass method in the $^{25}$Ne+n channel, we observe a sizable amount of E1 strength between 6 and 10 MeV. The reconstructed $^{26}$Ne angular distribution confirms its E1 nature. A reduced dipole transition probability of B(E1)=0.49$\pm$0.16 $e^2fm^2$ is deduced. For the first time, the decay pattern of low-lying strength in a neutron-rich nucleus is obtained. The results are discussed in terms of a pygmy resonance centered around 9 MeV.
The Telescope Array Collaboration, T. Abu-Zayyad, R. Aida, M. Allen, R. Anderson, R. Azuma, E. Barcikowski, J. W. Belz, D. R. Bergman, S. A. Blake, R. Cady, B. G. Cheon, J. Chiba, M. Chikawa, E. J. Cho, W. R. Cho, H. Fujii, T. Fujii, T. Fukuda, M. Fukushima, W. Hanlon, K. Hayashi, Y. Hayashi, N. Hayashida, K. Hibino, K. Hiyama, K. Honda, T. Iguchi, D. Ikeda, K. Ikuta, N. Inoue, T. Ishii, R. Ishimori, H. Ito, D. Ivanov, S. Iwamoto, C. C. H. Jui, K. Kadota, F. Kakimoto, O. Kalashev, T. Kanbe, K. Kasahara, H. Kawai, S. Kawakami, S. Kawana, E. Kido, H. B. Kim, H. K. Kim, J. H. Kim, J. H. Kim, K. Kitamoto, S. Kitamura, Y. Kitamura, K. Kobayashi, Y. Kobayashi, Y. Kondo, K. Kuramoto, V. Kuzmin, Y. J. Kwon, J. Lan, S. I. Lim, J. P. Lundquist, S. Machida, K. Martens, T. Matsuda, T. Matsuura, T. Matsuyama, J. N. Matthews, I. Myers, M. Minamino, K. Miyata, Y. Murano, S. Nagataki, T. Nakamura, S. W. Nam, T. Nonaka, S. Ogio, J. Ogura, M. Ohnishi, H. Ohoka, K. Oki, D. Oku, T. Okuda, M. Ono, A. Oshima, S. Ozawa, I. H. Park, M. S. Pshirkov, D. C. Rodriguez, S. Y. Roh, G. Rubtsov, D. Ryu, H. Sagawa, N. Sakurai, A. L. Sampson, L. M. Scott, P. D. Shah, F. Shibata, T. Shibata, H. Shimodaira, B. K. Shin, J. I. Shin, T. Shirahama, J. D. Smith, P. Sokolsky, T. J. Sonley, R. W. Springer, B. T. Stokes, S. R. Stratton, T. A. Stroman, S. Suzuki, Y. Takahashi, M. Takeda, A. Taketa, M. Takita, Y. Tameda, H. Tanaka, K. Tanaka, M. Tanaka, S. B. Thomas, G. B. Thomson, P. Tinyakov, I. Tkachev, H. Tokuno, T. Tomida, S. Troitsky, Y. Tsunesada, K. Tsutsumi, Y. Tsuyuguchi, Y. Uchihori, S. Udo, H. Ukai, G. Vasiloff, Y. Wada, T. Wong, Y. Yamakawa, R. Yamane, H. Yamaoka, K. Yamazaki, J. Yang, Y. Yoneda, S. Yoshida, H. Yoshii, R. Zollinger, Z. Zundel
May 27, 2013·astro-ph.HE·PDF We present a measurement of the energy spectrum of ultra-high-energy cosmic rays performed by the Telescope Array experiment using monocular observations from its two new FADC-based fluorescence detectors. After a short description of the experiment, we describe the data analysis and event reconstruction procedures. Since the aperture of the experiment must be calculated by Monte Carlo simulation, we describe this calculation and the comparisons of simulated and real data used to verify the validity of the aperture calculation. Finally, we present the energy spectrum calculated from the merged monocular data sets of the two FADC-based detectors, and also the combination of this merged spectrum with an independent, previously published monocular spectrum measurement performed by Telescope Array's third fluorescence detector (Abu-Zayyad {\it et al.}, {Astropart. Phys.} 39 (2012), 109). This combined spectrum corroborates the recently published Telescope Array surface detector spectrum (Abu-Zayyad {\it et al.}, {Astrophys. Journ.} 768 (2013), L1) with independent systematic uncertainties.
T. Sumikama, K. Yoshinaga, H. Watanabe, S. Nishimura, Y. Miyashita, K. Yamaguchi, K. Sugimoto, J. Chiba, Z. Li, H. Baba, J. S. Berryman, N. Blasi, A. Bracco, F. Camera, P. Doornenbal, S. Go, T. Hashimoto, S. Hayakawa, C. Hinke, E. Ideguchi, T. Isobe, Y. Ito, D. G. Jenkins, Y. Kawada, N. Kobayashi, Y. Kondo, R. Krücken, S. Kubono, G. Lorusso, T. Nakano, M. Kurata-Nishimura, A. Odahara, H. J. Ong, S. Ota, Zs. Podolyák, H. Sakurai, H. Scheit, K. Steiger, D. Steppenbeck, S. Takano, A. Takashima, K. Tajiri, T. Teranishi, Y. Wakabayashi, P. M. Walker, O. Wieland, H. Yamaguchi
The low-lying states in 106Zr and 108Zr have been investigated by means of β-γ and isomer spectroscopy at the RI beam factory, respectively. A new isomer with a half-life of 620\pm150 ns has been identified in 108Zr. For the sequence of even-even Zr isotopes, the excitation energies of the first 2+ states reach a minimum at N = 64 and gradually increase as the neutron number increases up to N = 68, suggesting a deformed sub-shell closure at N = 64. The deformed ground state of 108Zr indicates that a spherical sub-shell gap predicted at N = 70 is not large enough to change the ground state of 108Zr to the spherical shape. The possibility of a tetrahedral shape isomer in 108Zr is also discussed.
P. Doornenbal, H. Scheit, N. Aoi, S. Takeuchi, K. Li, E. Takeshita, H. Wang, H. Baba, S. Deguchi, N. Fukuda, H. Geissel, R. Gernhäuser, J. Gibelin, I. Hachiuma, Y. Hara, C. Hinke, N. Inabe, K. Itahashi, S. Itoh, D. Kameda, S. Kanno, Y. Kawada, N. Kobayashi, Y. Kondo, R. Krücken, T. Kubo, T. Kuboki, K. Kusaka, M. Lantz, S. Michimasa, T. Motobayashi, T. Nakamura, T. Nakao, K. Namihira, S. Nishimura, T. Ohnishi, M. Ohtake, N. A. Orr, H. Otsu, K. Ozeki, Y. Satou, S. Shimoura, T. Sumikama, M. Takechi, H. Takeda, K. N. Tanaka, K. Tanaka, Y. Togano, M. Winkler, Y. Yanagisawa, K. Yoneda, A. Yoshida, K. Yoshida, H. Sakurai
We report on the first spectroscopic study of the N=22 nucleus 32Ne at the newly completed RIKEN Radioactive Ion Beam Factory. A single gamma-ray line with an energy of 722(9) keV was observed in both inelastic scattering of a 226 MeV/u 32Ne beam on a Carbon target and proton removal from 33Na at 245 MeV/u. This transition is assigned to the de-excitation of the first J^pi = 2+ state in 32Ne to the 0+ ground state. Interpreted through comparison with state-of-the-art shell model calculations, the low excitation energy demonstrates that the Island of Inversion extends to at least N=22 for the Ne isotopes.
T. Abe, I. Adachi, K. Adamczyk, S. Ahn, H. Aihara, K. Akai, M. Aloi, L. Andricek, K. Aoki, Y. Arai, A. Arefiev, K. Arinstein, Y. Arita, D. M. Asner, V. Aulchenko, T. Aushev, T. Aziz, A. M. Bakich, V. Balagura, Y. Ban, E. Barberio, T. Barvich, K. Belous, T. Bergauer, V. Bhardwaj, B. Bhuyan, S. Blyth, A. Bondar, G. Bonvicini, A. Bozek, M. Bracko, J. Brodzicka, O. Brovchenko, T. E. Browder, G. Cao, M. -C. Chang, P. Chang, Y. Chao, V. Chekelian, A. Chen, K. -F. Chen, P. Chen, B. G. Cheon, C. -C. Chiang, R. Chistov, K. Cho, S. -K. Choi, K. Chung, A. Comerma, M. Cooney, D. E. Cowley, T. Critchlow, J. Dalseno, M. Danilov, A. Dieguez, A. Dierlamm, M. Dillon, J. Dingfelder, R. Dolenec, Z. Dolezal, Z. Drasal, A. Drutskoy, W. Dungel, D. Dutta, S. Eidelman, A. Enomoto, D. Epifanov, S. Esen, J. E. Fast, M. Feindt, M. Fernandez Garcia, T. Fifield, P. Fischer, J. Flanagan, S. Fourletov, J. Fourletova, L. Freixas, A. Frey, M. Friedl, R. Fruehwirth, H. Fujii, M. Fujikawa, Y. Fukuma, Y. Funakoshi, K. Furukawa, J. Fuster, N. Gabyshev, A. Gaspar de Valenzuela Cueto, A. Garmash, L. Garrido, Ch. Geisler, I. Gfall, Y. M. Goh, B. Golob, I. Gorton, R. Grzymkowski, H. Guo, H. Ha, J. Haba, K. Hara, T. Hara, T. Haruyama, K. Hayasaka, K. Hayashi, H. Hayashii, M. Heck, S. Heindl, C. Heller, T. Hemperek, T. Higuchi, Y. Horii, W. -S. Hou, Y. B. Hsiung, C. -H. Huang, S. Hwang, H. J. Hyun, Y. Igarashi, C. Iglesias, Y. Iida, T. Iijima, M. Imamura, K. Inami, C. Irmler, M. Ishizuka, K. Itagaki, R. Itoh, M. Iwabuchi, G. Iwai, M. Iwai, M. Iwasaki, M. Iwasaki, Y. Iwasaki, T. Iwashita, S. Iwata, H. Jang, X. Ji, T. Jinno, M. Jones, T. Julius, T. Kageyama, D. H. Kah, H. Kakuno, T. Kamitani, K. Kanazawa, P. Kapusta, S. U. Kataoka, N. Katayama, M. Kawai, Y. Kawai, T. Kawasaki, J. Kennedy, H. Kichimi, M. Kikuchi, C. Kiesling, B. K. Kim, G. N. Kim, H. J. Kim, H. O. Kim, J. -B. Kim, J. H. Kim, M. J. Kim, S. K. Kim, K. T. Kim, T. Y. Kim, K. Kinoshita, K. Kishi, B. Kisielewski, K. Kleese van Dam, J. Knopf, B. R. Ko, M. Koch, P. Kodys, C. Koffmane, Y. Koga, T. Kohriki, S. Koike, H. Koiso, Y. Kondo, S. Korpar, R. T. Kouzes, Ch. Kreidl, M. Kreps, P. Krizan, P. Krokovny, H. Krueger, A. Kruth, W. Kuhn, T. Kuhr, R. Kumar, T. Kumita, S. Kupper, A. Kuzmin, P. Kvasnicka, Y. -J. Kwon, C. Lacasta, J. S. Lange, I. -S. Lee, M. J. Lee, M. W. Lee, S. -H. Lee, M. Lemarenko, J. Li, W. D. Li, Y. Li, J. Libby, A. Limosani, C. Liu, H. Liu, Y. Liu, Z. Liu, D. Liventsev, A. Lopez Virto, Y. Makida, Z. P. Mao, C. Marinas, M. Masuzawa, D. Matvienko, W. Mitaroff, K. Miyabayashi, H. Miyata, Y. Miyazaki, T. Miyoshi, R. Mizuk, G. B. Mohanty, D. Mohapatra, A. Moll, T. Mori, A. Morita, Y. Morita, H. -G. Moser, D. Moya Martin, T. Mueller, D. Muenchow, J. Murakami, S. S. Myung, T. Nagamine, I. Nakamura, T. T. Nakamura, E. Nakano, H. Nakano, M. Nakao, H. Nakazawa, S. -H. Nam, Z. Natkaniec, E. Nedelkovska, K. Negishi, S. Neubauer, C. Ng, J. Ninkovic, S. Nishida, K. Nishimura, E. Novikov, T. Nozaki, S. Ogawa, K. Ohmi, Y. Ohnishi, T. Ohshima, N. Ohuchi, K. Oide, S. L. Olsen, M. Ono, Y. Ono, Y. Onuki, W. Ostrowicz, H. Ozaki, P. Pakhlov, G. Pakhlova, H. Palka, H. Park, H. K. Park, L. S. Peak, T. Peng, I. Peric, M. Pernicka, R. Pestotnik, M. Petric, L. E. Piilonen, A. Poluektov, M. Prim, K. Prothmann, K. Regimbal, B. Reisert, R. H. Richter, J. Riera-Babures, A. Ritter, A. Ritter, M. Ritter, M. Roehrken, J. Rorie, M. Rosen, M. Rozanska, L. Ruckman, S. Rummel, V. Rusinov, R. M. Russell, S. Ryu, H. Sahoo, K. Sakai, Y. Sakai, L. Santelj, T. Sasaki, N. Sato, Y. Sato, J. Scheirich, J. Schieck, C. Schwanda, A. J. Schwartz, B. Schwenker, A. Seljak, K. Senyo, O. -S. Seon, M. E. Sevior, M. Shapkin, V. Shebalin, C. P. Shen, H. Shibuya, S. Shiizuka, J. -G. Shiu, B. Shwartz, F. Simon, H. J. Simonis, J. B. Singh, R. Sinha, M. Sitarz, P. Smerkol, A. Sokolov, E. Solovieva, S. Stanic, M. Staric, J. Stypula, Y. Suetsugu, S. Sugihara, T. Sugimura, K. Sumisawa, T. Sumiyoshi, K. Suzuki, S. Y. Suzuki, H. Takagaki, F. Takasaki, H. Takeichi, Y. Takubo, M. Tanaka, S. Tanaka, N. Taniguchi, E. Tarkovsky, G. Tatishvili, M. Tawada, G. N. Taylor, Y. Teramoto, I. Tikhomirov, K. Trabelsi, T. Tsuboyama, K. Tsunada, Y. -C. Tu, T. Uchida, S. Uehara, K. Ueno, T. Uglov, Y. Unno, S. Uno, P. Urquijo, Y. Ushiroda, Y. Usov, S. Vahsen, M. Valentan, P. Vanhoefer, G. Varner, K. E. Varvell, P. Vazquez, I. Vila, E. Vilella, A. Vinokurova, J. Visniakov, M. Vos, C. H. Wang, J. Wang, M. -Z. Wang, P. Wang, A. Wassatch, M. Watanabe, Y. Watase, T. Weiler, N. Wermes, R. E. Wescott, E. White, J. Wicht, L. Widhalm, K. M. Williams, E. Won, H. Xu, B. D. Yabsley, H. Yamamoto, H. Yamaoka, Y. Yamaoka, M. Yamauchi, Y. Yin, H. Yoon, J. Yu, C. Z. Yuan, Y. Yusa, D. Zander, M. Zdybal, Z. P. Zhang, J. Zhao, L. Zhao, Z. Zhao, V. Zhilich, P. Zhou, V. Zhulanov, T. Zivko, A. Zupanc, O. Zyukova
Y. L. Sun, A. Corsi, Y. Kubota, G. Authelet, H. Baba, C. Caesar, D. Calvet, A. Delbart, M. Dozono, J. Feng, F. Flavigny, J. -M. Gheller, J. Gibelin, A. Giganon, A. Gillibert, S. Giraud, K. Hasegawa, T. Isobe, Y. Kanaya, S. Kawakami, D. Kim, Y. Kiyokawa, M. Kobayashi, N. Kobayashi, T. Kobayashi, Y. Kondo, Z. Korkulu, S. Koyama, V. Lapoux, Y. Maeda, F. M. Marques, T. Miyazaki, T. Motobayashi, T. Nakamura, N. Nakatsuka, Y. Nishio, A. Obertelli, A. Ohkura, N. A. Orr, S. Ota, H. Otsu, T. Ozaki, V. Panin, S. Paschalis, E. C. Pollacco, S. Reichert, J. -Y. Rousse, A. T. Saito, S. Sakaguchi, M. Sako, C. Santamaria, M. Sasano, H. Sato, M. Shikata, Y. Shimizu, Y. Shindo, L. Stuhl, T. Sumikama, M. Tabata, Y. Togano, J. Tsubota, Z. H. Yang, J. Yasuda, K. Yoneda, J. Zenihiro, T. Uesaka
We report on the two-body invariant-mass spectroscopy of $^{9}$He, populated via the 1$p$1$n$ knockout reaction from the two-neutron halo nucleus $^{11}$Li at $\sim$250 MeV/nucleon. A broad $p$-wave resonant state of $^{9}$He was observed at 1.28(1) MeV with a width of 0.82(4) MeV.
T. Abu-Zayyad, R. Aida, M. Allen, R. Anderson, R. Azuma, E. Barcikowski, J. W. Belz, D. R. Bergman, S. A. Blake, R. Cady, B. G. Cheon, J. Chiba, M. Chikawa, E. J. Cho, W. R. Cho, H. Fujii, T. Fujii, T. Fukuda, M. Fukushima, D. Gorbunov, W. Hanlon, K. Hayashi, Y. Hayashi, N. Hayashida, K. Hibino, K. Hiyama, K. Honda, T. Iguchi, D. Ikeda, K. Ikuta, N. Inoue, T. Ishii, R. Ishimori, D. Ivanov, S. Iwamoto, C. C. H. Jui, K. Kadota, F. Kakimoto, O. Kalashev, T. Kanbe, K. Kasahara, H. Kawai, S. Kawakami, S. Kawana, E. Kido, H. B. Kim, H. K. Kim, J. H. Kim, J. H. Kim, K. Kitamoto, S. Kitamura, Y. Kitamura, K. Kobayashi, Y. Kobayashi, Y. Kondo, K. Kuramoto, V. Kuzmin, Y. J. Kwon, S. I. Lim, S. Machida, K. Martens, J. Martineau, T. Matsuda, T. Matsuura, T. Matsuyama, J. N. Matthews, M. Minamino, K. Miyata, Y. Murano, S. Nagataki, T. Nakamura, S. W. Nam, T. Nonaka, S. Ogio, M. Ohnishi, H. Ohoka, K. Oki, D. Oku, T. Okuda, A. Oshima, S. Ozawa, I. H. Park, M. S. Pshirkov, D. C. Rodriguez, S. Y. Roh, G. Rubtsov, D. Ryu, H. Sagawa, N. Sakurai, A. L. Sampson, L. M. Scott, P. D. Shah, F. Shibata, T. Shibata, H. Shimodaira, B. K. Shin, J. I. Shin, T. Shirahama, J. D. Smith, P. Sokolsky, T. J. Sonley, R. W. Springer, B. T. Stokes, S. R. Stratton, T. Stroman, S. Suzuki, Y. Takahashi, M. Takeda, A. Taketa, M. Takita, Y. Tameda, H. Tanaka, K. Tanaka, M. Tanaka, S. B. Thomas, G. B. Thomson, P. Tinyakov, I. Tkachev, H. Tokuno, T. Tomida, S. Troitsky, Y. Tsunesada, K. Tsutsumi, Y. Tsuyuguchi, Y. Uchihori, S. Udo, H. Ukai, G. Vasiloff, Y. Wada, T. Wong, M. Wood, Y. Yamakawa, R. Yamane, H. Yamaoka, K. Yamazaki, J. Yang, Y. Yoneda, S. Yoshida, H. Yoshii, R. Zollinger, Z. Zundel
Feb 23, 2012·astro-ph.IM·PDF The Telescope Array's Middle Drum fluorescence detector was instrumented with telescopes refurbished from the High Resolution Fly's Eye's HiRes-1 site. The data observed by Middle Drum in monocular mode was analyzed via the HiRes-1 profile-constrained geometry reconstruction technique and utilized the same calibration techniques enabling a direct comparison of the energy spectra and energy scales between the two experiments. The spectrum measured using the Middle Drum telescopes is based on a three-year exposure collected between December 16, 2007 and December 16, 2010. The calculated difference between the spectrum of the Middle Drum observations and the published spectrum obtained by the data collected by the HiRes-1 site allows the HiRes-1 energy scale to be transferred to Middle Drum. The HiRes energy scale is applied to the entire Telescope Array by making a comparison between Middle Drum monocular events and hybrid events that triggered both Middle Drum and the Telescope Array's scintillator Ground Array.
T. Abu-Zayyad, R. Aida, M. Allen, R. Anderson, R. Azuma, E. Barcikowski, J. W. Belz, D. R. Bergman, S. A. Blake, R. Cady, B. G. Cheon, J. Chiba, M. Chikawa, E. J. Cho, W. R. Cho, H. Fujii, T. Fujii, T. Fukuda, M. Fukushima, W. Hanlon, K. Hayashi, Y. Hayashi, N. Hayashida, K. Hibino, K. Hiyama, K. Honda, T. Iguchi, D. Ikeda, K. Ikuta, N. Inoue, T. Ishii, R. Ishimori, D. Ivanov, S. Iwamoto, C. C. H. Jui, K. Kadota, F. Kakimoto, O. Kalashev, T. Kanbe, K. Kasahara, H. Kawai, S. Kawakami, S. Kawana, E. Kido, H. B. Kim, H. K. Kim, J. H. Kim, J. H. Kim, K. Kitamoto, S. Kitamura, Y. Kitamura, K. Kobayashi, Y. Kobayashi, Y. Kondo, K. Kuramoto, V. Kuzmin, Y. J. Kwon, S. I. Lim, S. Machida, K. Martens, J. Martineau, T. Matsuda, T. Matsuura, T. Matsuyama, J. N. Matthews, M. Minamino, K. Miyata, Y. Murano, I. Myers, K. Nagasawa, S. Nagataki, T. Nakamura, S. W. Nam, T. Nonaka, S. Ogio, M. Ohnishi, H. Ohoka, K. Oki, D. Oku, T. Okuda, A. Oshima, S. Ozawa, I. H. Park, M. S. Pshirkov, D. C. Rodriguez, S. Y. Roh, G. Rubtsov, D. Ryu, H. Sagawa, N. Sakurai, A. L. Sampson, L. M. Scott, P. D. Shah, F. Shibata, T. Shibata, H. Shimodaira, B. K. Shin, J. I. Shin, T. Shirahama, J. D. Smith, P. Sokolsky, T. J. Sonley, R. W. Springer, B. T. Stokes, S. R. Stratton, T. Stroman, S. Suzuki, Y. Takahashi, M. Takeda, A. Taketa, M. Takita, Y. Tameda, H. Tanaka, K. Tanaka, M. Tanaka, S. B. Thomas, G. B. Thomson, P. Tinyakov, I. Tkachev, H. Tokuno, T. Tomida, S. Troitsky, Y. Tsunesada, K. Tsutsumi, Y. Tsuyuguchi, Y. Uchihori, S. Udo, H. Ukai, G. Vasiloff, Y. Wada, T. Wong, M. Wood, Y. Yamakawa, R. Yamane, H. Yamaoka, K. Yamazaki, J. Yang, Y. Yoneda, S. Yoshida, H. Yoshii, X. Zhou, R. Zollinger, Z. Zundel
May 27, 2012·astro-ph.HE·PDF We study the anisotropy of Ultra-High Energy Cosmic Ray (UHECR) events collected by the Telescope Array (TA) detector in the first 40 months of operation. Following earlier studies, we examine event sets with energy thresholds of 10 EeV, 40 EeV, and 57 EeV. We find that the distributions of the events in right ascension and declination are compatible with an isotropic distribution in all three sets. We then compare with previously reported clustering of the UHECR events at small angular scales. No significant clustering is found in the TA data. We then check the events with E>57 EeV for correlations with nearby active galactic nuclei. No significant correlation is found. Finally, we examine all three sets for correlations with the large-scale structure of the Universe. We find that the two higher-energy sets are compatible with both an isotropic distribution and the hypothesis that UHECR sources follow the matter distribution of the Universe (the LSS hypothesis), while the event set with E>10 EeV is compatible with isotropy and is not compatible with the LSS hypothesis at 95% CL unless large deflection angles are also assumed. We show that accounting for UHECR deflections in a realistic model of the Galactic magnetic field can make this set compatible with the LSS hypothesis.
B. Monteagudo, F. M. Marqués, J. Gibelin, N. A. Orr, A. Corsi, Y. Kubota, J. Casal, J. Gómez-Camacho, G. Authelet, H. Baba, C. Caesar, D. Calvet, A. Delbart, M. Dozono, J. Feng, F. Flavigny, J. -M. Gheller, A. Giganon, A. Gillibert, K. Hasegawa, T. Isobe, Y. Kanaya, S. Kawakami, D. Kim, Y. Kiyokawa, M. Kobayashi, N. Kobayashi, T. Kobayashi, Y. Kondo, Z. Korkulu, S. Koyama, V. Lapoux, Y. Maeda, T. Motobayashi, T. Miyazaki, T. Nakamura, N. Nakatsuka, Y. Nishio, A. Obertelli, A. Ohkura, S. Ota, H. Otsu, T. Ozaki, V. Panin, S. Paschalis, E. C. Pollacco, S. Reichert, J. -Y. Rousse, A. T. Saito, S. Sakaguchi, M. Sako, C. Santamaria, M. Sasano, H. Sato, M. Shikata, Y. Shimizu, Y. Shindo, L. Stuhl, T. Sumikama, Y. L. Sun, M. Tabata, Y. Togano, J. Tsubota, T. Uesaka, Z. H. Yang, J. Yasuda, K. Yoneda, J. Zenihiro
The structure and decay of the most neutron-rich beryllium isotope, $^{16}$Be, has been investigated following proton knockout from a high-energy $^{17}$B beam. Two relatively narrow resonances were observed for the first time, with energies of $0.84(3)$ and $2.15(5)$ MeV above the two-neutron decay threshold and widths of $0.32(8)$ and $0.95(15)$ MeV respectively. These were assigned to be the ground ($J^π=0^+$) and first excited ($2^+$) state, with $E_x=1.31(6)$ MeV. The mass excess of $^{16}$Be was thus deduced to be $56.93(13)$ MeV, some $0.5$ MeV more bound than the only previous measurement. Both states were observed to decay by direct two-neutron emission. Calculations incorporating the evolution of the wavefunction during the decay as a genuine three-body process reproduced the principal characteristics of the neutron-neutron energy spectra for both levels, indicating that the ground state exhibits a strong spatially compact dineutron component, while the 2$^+$ level presents a far more diffuse neutron-neutron distribution.
P. J. Li, D. Beaumel, J. Lee, M. Assié, S. Chen, S. Franchoo, J. Gibelin, F. Hammache, T. Harada, Y. Kanada-En'yo, Y. Kubota, S. Leblond, P. F. Liang, T. Lokotko, M. Lyu, F. M. Marqués, Y. Matsuda, K. Ogata, H. Otsu, E. Rindel, L. Stuhl, D. Suzuki, Y. Togano, T. Tomai, X. X. Xu, K. Yoshida, J. Zenihiro, N. L. Achouri, T. Aumann, H. Baba, G. Cardella, S. Ceruti, A. I. Stefanescu, A. Corsi, A. Frotscher, J. Gao, A. Gillibert, K. Inaba, T. Isobe, T. Kawabata, N. Kitamura, T. Kobayashi, Y. Kondo, A. Kurihara, H. N. Liu, H. Miki, T. Nakamura, A. Obertelli, N. A. Orr, V. Panin, M. Sasano, T. Shimada, Y. L. Sun, J. Tanaka, L. Trache, D. Tudor, T. Uesaka, H. Wang, H. Yamada, Z. H. Yang, M. Yasuda
The cluster structure of the neutron-rich isotope $^{10}$Be has been probed via the $(p,pα)$ reaction at 150 MeV/nucleon in inverse kinematics and in quasifree conditions. The populated states of $^{6}$He residues were investigated through missing mass spectroscopy. The triple differential cross-section for the ground-state transition was extracted for quasifree angle pairs ($θ_{p}$, $θ_α$) and compared to distorted-wave impulse approximation reaction calculations performed in a microscopic framework using successively the Tohsaki-Horiuchi-Schuck-Röpke product wave-function and the wave-function deduced from Antisymmetrized Molecular Dynamics calculations. The remarkable agreement between calculated and measured cross-sections in both shape and magnitude validates the molecular structure description of the $^{10}$Be ground-state, configured as an $α$-$α$ core with two valence neutrons occupying $π$-type molecular orbitals.
H. N. Liu, F. Flavigny, H. Baba, M. Boehmer, U. Bonnes, V. Borshchov, P. Doornenbal, N. Ebina, M. Enciu, A. Frotscher, R. Gernhäuser, V. Girard-Alcindor, D. Goupillière, J. Heuser, R. Kapell, Y. Kondo, H. Lee, J. Lehnert, T. Matsui, A. Matta, T. Nakamura, A. Obertelli, T. Pohl, M. Protsenko, M. Sasano, Y. Satou, C. J. Schmidt, K. Schünemann, C. Simons, Y. L. Sun, J. Tanaka, Y. Togano, T. Tomai, I. Tymchuk, T. Uesaka, R. Visinka, H. Wang, F. Wienholtz
STRASSE (Silicon Tracker for RAdioactive nuclei Studies at SAMURAI Experiments) is a new detection system under construction for quasi-free scattering (QFS) measurements at 200-250 MeV/nucleon at the RIBF facility of the RIKEN Nishina Center. It consists of a charged-particle silicon tracker coupled with a dedicated thick liquid hydrogen target (up to 150-mm long) in a compact geometry to fit inside large scintillator or germanium arrays. Its design was optimized for two types of studies using QFS: missing-mass measurements and in-flight prompt $γ$-ray spectroscopy. This article describes (i) the resolution requirements needed to go beyond the sensitivity of existing systems for these two types of measurements, (ii) the conceptual design of the system using detailed simulations of the setup and (iii) its complete technical implementation and challenges. The final tracker aims at a sub-mm reaction vertex resolution and is expected to reach a missing-mass resolution below 2 MeV in $σ$ for $(p,2p)$ reactions when combined with the CsI(Na) CATANA array.
A. Corsi, Y. Kubota, J. Casal, M. Gomez-Ramos, A. M. Moro, G. Authelet, H. Baba, C. Caesar, D. Calvet, A. Delbart, M. Dozono, J. Feng, F. Flavigny, J. -M. Gheller, J. Gibelin, A. Giganon, A. Gillibert, K. Hasegawa, T. Isobe, Y. Kanaya, S. Kawakami, D. Kim, Y. Kiyokawa, M. Kobayashi, N. Kobayashi, T. Kobayashi, Y. Kondo, Z. Korkulu, S. Koyama, V. Lapoux, Y. Maeda, F. M. Marques, T. Motobayashi, T. Miyazaki, T. Nakamura, N. Nakatsuka, Y. Nishio, A. Obertelli, A. Ohkura, N. A. Orr, S. Ota, H. Otsu, T. Ozaki, V. Panin, S. Paschalis, E. C. Pollacco, S. Reichert, J. -Y. Rousse, A. T. Saito, S. Sakaguchi, M. Sako, C. Santamaria, M. Sasano, H. Sato, M. Shikata, Y. Shimizu, Y. Shindo, L. Stuhl, T. Sumikama, Y. L. Sun, M. Tabata, Y. Togano, J. Tsubota, T. Uesaka, Z. H. Yang, J. Yasuda, K. Yoneda, J. Zenihiro
We present an investigation of the structure of 13Be obtained via a kinematically complete measurement of the (p; pn) reaction in inverse kinematics at 265 MeV/nucleon. The relative energy spectrum of 13Be is compared to Transfer-to-the-Continuum calculations which use as structure inputs the overlaps of the 14Be ground-state wave function, computed in a three-body model, with the unbound states of the 13Be residual nucleus. The key role of neutron p-wave orbital in the interpretation of the low-relative-energy part of the spectrum is discussed.
M. L. Cortés, W. Rodriguez, P. Doornenbal, A. Obertelli, J. D. Holt, S. M. Lenzi, J. Menéndez, F. Nowacki, K. Ogata, A. Poves, T. R. Rodríguez, A. Schwenk, J. Simonis, S. R. Stroberg, K. Yoshida, L. Achouri, H. Baba, F. Browne, D. Calvet, F. Château, S. Chen, N. Chiga, A. Corsi, A. Delbart, J-M. Gheller, A. Giganon, A. Gillibert, C. Hilaire, T. Isobe, T. Kobayashi, Y. Kubota, V. Lapoux, H. N. Liu, T. Motobayashi, I. Murray, H. Otsu, V. Panin, N. Paul, H. Sakurai, M. Sasano, D. Steppenbeck, L. Stuhl, Y. L. Sun, Y. Togano, T. Uesaka, K. Wimmer, K. Yoneda, O. Aktas, T. Aumann, L. X. Chung, F. Flavigny, S. Franchoo, I. Gašparić, R. -B. Gerst, J. Gibelin, K. I. Hahn, D. Kim, T. Koiwai, Y. Kondo, P. Koseoglou, J. Lee, C. Lehr, B. D. Linh, T. Lokotko, M. MacCormick, K. Moschner, T. Nakamura, S. Y. Park, D. Rossi, E. Sahin, D. Sohler, P. -A. Söderström, S. Takeuchi, H. Toernqvist, V. Vaquero, V. Wagner, S. Wang, V. Werner, X. Xu, H. Yamada, D. Yan, Z. Yang, M. Yasuda, L. Zanetti
Excited states in the $N=40$ isotone $^{62}$Ti were populated via the $^{63}$V$(p,2p)$$^{62}$Ti reaction at $\sim$200~MeV/u at the Radioactive Isotope Beam Factory and studied using $γ$-ray spectroscopy. The energies of the $2^+_1 \rightarrow 0^{+}_{\mathrm{gs}}$ and $4^+_1 \rightarrow 2^+_1$ transitions, observed here for the first time, indicate a deformed $^{62}$Ti ground state. These energies are increased compared to the neighboring $^{64}$Cr and $^{66}$Fe isotones, suggesting a small decrease of quadrupole collectivity. The present measurement is well reproduced by large-scale shell-model calculations based on effective interactions, while ab initio and beyond mean-field calculations do not yet reproduce our findings. The shell-model calculations for $^{62}$Ti show a dominant configuration with four neutrons excited across the $N=40$ gap. Likewise, they indicate that the $N=40$ island of inversion extends down to $Z=20$, disfavoring a possible doubly magic character of the elusive $^{60}$Ca.
Y. Kubota, A. Corsi, G. Authelet, H. Baba, C. Caesar, D. Calvet, A. Delbart, M. Dozono, J. Feng, F. Flavigny, J. -M. Gheller, J. Gibelin, A. Giganon, A. Gillibert, K. Hasegawa, T. Isobe, Y. Kanaya, S. Kawakami, D. Kim, Y. Kikuchi, Y. Kiyokawa, M. Kobayashi, N. Kobayashi, T. Kobayashi, Y. Kondo, Z. Korkulu, S. Koyama, V. Lapoux, Y. Maeda, F. M. Marqués, T. Motobayashi, T. Miyazaki, T. Nakamura, N. Nakatsuka, Y. Nishio, A. Obertelli, K. Ogata, A. Ohkura, N. A. Orr, S. Ota, H. Otsu, T. Ozaki, V. Panin, S. Paschalis, E. C. Pollacco, S. Reichert, J. -Y. Roussé, A. T. Saito, S. Sakaguchi, M. Sako, C. Santamaria, M. Sasano, H. Sato, M. Shikata, Y. Shimizu, Y. Shindo, L. Stuhl, T. Sumikama, Y. L. Sun, M. Tabata, Y. Togano, J. Tsubota, Z. H. Yang, J. Yasuda, K. Yoneda, J. Zenihiro, T. Uesaka
The formation of a dineutron in the nucleus $^{11}$Li is found to be localized to the surface region. The experiment measured the intrinsic momentum of the struck neutron in $^{11}$Li via the $(p,pn)$ knockout reaction at 246 MeV/nucleon. The correlation angle between the two neutrons is, for the first time, measured as a function of the intrinsic neutron momentum. A comparison with reaction calculations reveals the localization of the dineutron at $r\sim3.6$ fm. The results also support the density dependence of dineutron formation as deduced from Hartree-Fock-Bogoliubov calculations for nuclear matter.
M. Abe, S. Bae, G. Beer, G. Bunce, H. Choi, S. Choi, M. Chung, W. da Silva, S. Eidelman, M. Finger, Y. Fukao, T. Fukuyama, S. Haciomeroglu, K. Hasegawa, K. Hayasaka, N. Hayashizaki, H. Hisamatsu, T. Iijima, H. Iinuma, K. Inami, H. Ikeda, M. Ikeno, K. Ishida, T. Itahashi, M. Iwasaki, Y. Iwashita, Y. Iwata, R. Kadono, S. Kamal, T. Kamitani, S. Kanda, F. Kapusta, K. Kawagoe, N. Kawamura, R. Kitamura, B. Kim, Y. Kim, T. Kishishita, H. Ko, T. Kohriki, Y. Kondo, T. Kume, M. J. Lee, S. Lee, W. Lee, G. M. Marshall, Y. Matsuda, T. Mibe, Y. Miyake, T. Murakami, K. Nagamine, H. Nakayama, S. Nishimura, D. Nomura, T. Ogitsu, S. Ohsawa, K. Oide, Y. Oishi, S. Okada, A. Olin, Z. Omarov, M. Otani, G. Razuvaev, A. Rehman, N. Saito, N. F. Saito, K. Sasaki, O. Sasaki, N. Sato, Y. Sato, Y. K. Semertzidis, H. Sendai, Y. Shatunov, K. Shimomura, M. Shoji, B. Shwartz, P. Strasser, Y. Sue, T. Suehara, C. Sung, K. Suzuki, T. Takatomi, M. Tanaka, J. Tojo, Y. Tsutsumi, T. Uchida, K. Ueno, S. Wada, E. Won, H. Yamaguchi, T. Yamanaka, A. Yamamoto, T. Yamazaki, H. Yasuda, M. Yoshida, T. Yoshioka
This paper introduces a new approach to measure the muon magnetic moment anomaly $a_μ = (g-2)/2$, and the muon electric dipole moment (EDM) $d_μ$ at the J-PARC muon facility. The goal of our experiment is to measure $a_μ$ and $d_μ$ using an independent method with a factor of 10 lower muon momentum, and a factor of 20 smaller diameter storage-ring solenoid compared with previous and ongoing muon $g-2$ experiments with unprecedented quality of the storage magnetic field. Additional significant differences from the present experimental method include a factor of 1,000 smaller transverse emittance of the muon beam (reaccelerated thermal muon beam), its efficient vertical injection into the solenoid, and tracking each decay positron from muon decay to obtain its momentum vector. The precision goal for $a_μ$ is statistical uncertainty of 450 part per billion (ppb), similar to the present experimental uncertainty, and a systematic uncertainty less than 70 ppb. The goal for EDM is a sensitivity of $1.5\times 10^{-21}~e\cdot\mbox{cm}$.
T. Nishikawa, S. Saito, Y. Kondo
We derive new QCD sum rules for the axial coupling constants by considering two-point correlation functions of the axial-vector currents in a one nucleon state. The QCD sum rules tell us that the axial coupling constants are expressed by nucleon matrix elements of quark and gluon operators which are related to the sigma terms and the moments of parton distribution functions. The results for the iso-vector axial coupling constants and the 8th component of the SU(3) octet are in good agreement with experiment.