M. Iio

Precision measurement of the 3d → 2p x-ray energy in kaonic 4He

Abstract We have measured the Balmer-series x-rays of kaonic 4 He atoms using novel large-area silicon drift x-ray detectors in order to study the low-energy K ¯ -nucleus strong interaction. The energy of the 3 d → 2 p transition was determined to be 6467 ± 3 ( stat ) ± 2 ( syst ) eV . The resulting strong-interaction energy-level shift is in agreement with theoretical calculations, thus eliminating a long-standing discrepancy between theory and experiment.

Search for strange tribaryon states in the inclusive 4He(Kstopped−,p) reaction

Abstract A search for tribaryon states was performed at KEK-PS. We adopted the 4 He( K stopped − , p ) reaction to populate the states with strangeness −1, charge 0 and isospin 1. No significant narrow structure was observed in the mass region from 3000 to 3200 MeV / c 2 in an inclusive missing mass spectrum. The upper limit of the formation branching ratio was determined to be ( 0.4 – 6 ) × 10 −4 , ( 0.2 – 6 ) × 10 −3 and ( 0.06 – 5 ) × 10 −2 / ( stopped K − ) with 95% confidence level for a narrow state with an assumed width of 0, 20 and 40 MeV / c 2 , respectively.

Search for the deeply bound K–pp state from the semi-inclusive forward-neutron spectrum in the in-flight K– reaction on helium-3

T. Hashimoto †1,*, S. Ajimura2, G. Beer3, H. Bhang4, M. Bragadireanu5, L. Busso7,8, M. Cargnelli6, S. Choi4, C. Curceanu9, S. Enomoto2, D. Faso7,8, H. Fujioka10, Y. Fujiwara1, T. Fukuda11, C. Guaraldo9, R. S. Hayano1, T. Hiraiwa2, M. Iio12, M. Iliescu9, K. Inoue13, Y. Ishiguro10, T. Ishikawa1, S. Ishimoto12, K. Itahashi14, M. Iwai12, M. Iwasaki14,15, Y. Kato14, S. Kawasaki13, P. Kienle‡16, H. Kou15, Y. Ma14, J. Marton6, Y. Matsuda17, Y. Mizoi11, O. Morra7, T. Nagae10, H. Noumi2, H. Ohnishi14,2, S. Okada14, H. Outa14, K. Piscicchia9, M. Poli Lener9, A. Romero Vidal9, Y. Sada10, A. Sakaguchi13, F. Sakuma14, M. Sato14, A. Scordo9, M. Sekimoto12, H. Shi9, D. Sirghi9,5, F. Sirghi9,5, S. Suzuki12, T. Suzuki1, K. Tanida4, H. Tatsuno1, M. Tokuda15, D. Tomono10, A. Toyoda12, K. Tsukada18, O. Vazquez Doce9,19, E. Widmann6, T. Yamaga13, T. Yamazaki1,14, H. Yim20, Q. Zhang14, and J. Zmeskal6

Design Optimization of the New D1 Dipole for HL-LHC Upgrade

The High-Luminosity Large Hadron Collider upgrade (LHC) project aims to increase the peak luminosity of the LHC to 5 ×1034 cm - 2s - 1, and a total integrated luminosity of 3000 fb - 1 from 2020 to 2030 by upgrading the low-beta insertion system for the ATLAS and CMS experiments. The aperture of the insertion magnets including the focusing/defocusing quadrupoles and separation dipoles will be doubled to achieve a smaller β*. This paper presents the latest design updates of the separation dipole D1 magnet, including the study of the different cable types to vary the main field; the modifications of the iron shape for the new design options to minimize the iron saturation effect on field quality; and the optimization of the coil ends to reduce the peak field and higher order harmonic field integrals in the ends.

Design of a Large Single-Aperture Dipole Magnet for HL-LHC Upgrade

An upgrade of the low-beta insertion system for the ATLAS and Compact Muon Solenoid experiments is proposed in the high luminosity Large Hadron Collider upgrade project. It includes final beam focusing quadrupoles, beam separation and recombination dipoles, and larger aperture matching section quadrupoles. KEK is in charge of the conceptual design of the large aperture separation dipole D1. The latest design parameters are a main field of ~ 5 T at 1.9 K with Nb-Ti superconducting technology, a coil aperture of 160 mm, and a cos-theta one-layer coil with Large Hadron Collider dipole cable. Because the new D1 is expected to be operated in a very high radiation environment, radiation resistance and a cooling scheme are being carefully considered. The collaring-yoke structure is adopted to provide the mechanical support for the single-layer Nb-Ti coil. We summarize the design study of this magnet, including i) the very large iron saturation effect on field quality due to the large aperture and limited size of the iron yoke, ii) the stray field at the outer surface of the iron cryostat, and iii) the stress management from room temperature assembly to final operation.

Development of Indirect-Cooling Radiation-Resistant Magnets

In a high-intensity proton beam facility, beam line elements downstream of a production target are exposed to a huge amount of radiation and heat. Beam pipes are closer to the beam than the magnet poles and more difficult to cool sufficiently without tritium production. Therefore, the magnets are placed in a large vacuum chamber, instead of using vacuum pipes located within the pole gaps. We have adopted indirect-cooling mineral-insulation-cable (MIC) coils for these magnets. They have a great advantage that the mechanical strength and the insulation performance can be significantly improved by avoiding the use of ceramic insulation pipes, because electric circuits are completely separated from water passages. We have made coils using 1000-A-class solid-conductor MICs and stainless-steel pipes, and tested magnet operation in vacuum. By improving the structure of end parts of MICs and increasing their emissivity, we have successfully fed the current of DC 1000 A to the solid-conductor MIC coils in vacuum.

YN CORRELATIONS FROM THE STOPPED K−REACTION ON4He

We have investigated correlations of coincident

Status of Superconducting Solenoid System for COMET Phase-I Experiment at J-PARC

\Lambda N

The K1.8BR spectrometer system at J-PARC

pairs from the stopped

Structure near

K^-