119456897
Spectroscopy of hypernuclei with stopped kaons — recent result of KEK experiment
Abstract Pion momentum spectra from K − absorption at rest on various nuclear targets were measured by means of a magnetic spectrometer with wide momentum range (100 ∼ 300 MeV/c). The ground state of Σ − hypernucleus, if well bound with a narrow width, is expected to be populated in 12 C(stopped K − , π + ) inclusive (untagged) spectrum, but such a peak was not observed. The spectrum is compared with the DWIA calculations by Morimatsu and Yazaki, indicating that the depth of the nuclear potential of Σ − is shallower than 12 MeV, and that its imaginary part is larger than 5 MeV if the potential depth is about 10 MeV. In the 12 C(stopped K − , π − ) spectrum, the ground state (( p 3 2 ) n −1 ( s 1 2 )Λ) and the excited states (( p3 2 ) n −1 ( p )Λ) of Λ 12 C were observed, and their formation probabilities were roughly in agreement with the results of DWIA calculations. In the π − spectra on 12 C, 9 Be, and 7 Li targets a distinct peak was observed at 132.1±0.7 MeV/c. It is ascribed to π − from the mesic decay of Λ 4 H; Λ 4 H → 4 He π − . The formation probability of Λ 4 H on C, Be, or Li target is much larger than those of the discrete states of Λ 12 C via the direct (stopped K − , π − ) reaction.
121882195
Discovery of the repulsive energy shift of the kaonic hydrogen 1s state
Abstract The aim in this manuscript is to clarify the progress in understanding the nature of the K ¯ N interaction at the lowest energy, given by the recent kaonic hydrogen X-ray experiment at KEK [1]. We have observed a clear spectrum showing the kaonic hydrogen K α line, for the first time. The analysis gives the repulsive energy shift to be Δ E (1 s ) = −323 ± 63(statistical) ± 11 (systematic) eV and the energy width to be Λ(1 s ) = 407 ± 208 ± 100 eV. This result is consistent with analyses of the previous low-energy scattering data and resolves the long-standing kaonic hydrogen puzzle.
124815658
Measure of the spatial size for the monopole excitation in proton scattering
122600834
Muon catalyzed fusion experiments on muonic deuterium atom deceleration in thin solid deuterium films
Abstract Muon catalyzed fusion was investigated in a series of thin solid deuterium films by detecting protons from dd fusion. Two different contributions to the total fusion yield resulting from dμ atoms emitted from a primary hydrogen layer and from incident muons directly stopped in the deuterium film itself were observed. The thickness dependence of the fusion yield suggested the importance of molecular effects in dμ elastic scattering in D 2 .
124123633
SEARCH FOR LORENTZ AND CPT VIOLATION EFFECTS IN MUON SPIN PRECESSION
117791711
Radioactive Muonic Atom Studies with Intense Muon Beams
New intense muon beams with flux several orders of magnitude higher than at present muon facilities would allow many novel experimental studies that were until now statistically not feasible. The investigation of the nuclear properties of short‐lived nuclei using muonic atom spectroscopy would become possible. In this paper, the recent progress of a feasibility study at RIKEN‐RAL muon facility using the cold hydrogen film method to produce radioactive muonic atoms is being reported. The first experimental results have just been obtained with stable argon ions implanted in solid deuterium films.
67846515
A Modified Glauber Approximation and the Formation of Shock Waves in High-Energy Heavy Ion Collisions
Coherent features in high energy heavy ion collisions are investigated from a microscopic viewpoint. A modified Glauber approximation which enables us to include the slowing down of the relative motion between the centers of masses of both nuclei is presented. The generation of the shock wave is shown to be suppressed by this slowing down effect. As an application inclusive nucleon spectra and the two-particle correlation are calculated in the case of Ne+U collision at 400 Me V! A. l ) (which are referred to as I hereafter) we investigated a possible microscopic mechanism for shock wave generation in high energy heavy ion collisions. The nuclear excitation induced by a nuclear collision was de­ scribed in terms of phonons. It was shown that as the collision proceeds phonons are coherently excited and show a characteristic feature of the shock wave. In this treatment the action of the projectile on the target was replaced by that of a potential moving with a constant velocity. We may construct this potential by superposing the nucleonic potential between projectile nucleons and the target ones with amplitudes of nucleonic states in both nuclei. To treat both systems equally from a microscopic viewpoint, one of the authors (M.I) proposed a formalism which is essentially an application of the Glauber approximation to the process. 2 ) The assembly of nucleons in the projectile nucleus was assumed to move in a group during the collision and the Glauber approximation was applied to the relative motion between the centers of masses of the projectile and the target nucleus. In this treatment the deceleration of the relative motion due to the nuclear excitation was not taken into account. In this paper we extend the Glauber approximation so as to take into account the slowing down of the relative motion. In § 2 the formulation of the modified Glauber approximation is presented.
110271540
Compact 8-lead unit for the SC correction coils of the SuperKEKB IR magnet system
In the proposed SuperKEKB interaction region (IR) magnet system 40superconducting (SC) correction coils are designed to perform some specific functions withcurrent of about 50 A. To energize these coils, 80 current leads will be mounted in thecryostats where the stringent spatial constraint and the cryogenic operation require acompact and optimum design. We propose a compact unit to integrate 8 helium vaporcooled leads (4 pairs). The 8 leads are made of brass and consist of two structures for thetransported current and helium vapor, which are designed and simulated by finite elementmodel (FEM). This paper will introduce the material selection and structure details. To equalize the temperature profiles of the individual leads under the different currents and helium flows, some copper blocks are placed between leads. In the cold test, the 8 leadswere operated in the nominal mode and responded safely to some transient situation. This paper will present the thermal and electrical comparison between the experi...
115798893
Linear Collider vertex detector optimization for Higgs branching ratio measurements
The Higgs branching ratio measurement is a premier goal of the next Linear Collider physics program. Variations of a CCD vertex detector have been studied to assess the impact of inner radius and hit precision on the measurement of the Higgs branching ratios. A small dependence is found when the beampipe radius is varied between 1.2 cm and 2.4 cm, and the hit precision between 3 μm and 5 μm.
56000332
PROGRESS OF DESIGN STUDY OF INTERACTION REGION QUADRUPOLES FOR THE SUPER-KEKB
For KEKB upgrade, we are studying the design of the final focus quadrupoles to achieve very small β-functions at the interaction point (IP). For each beam, the final beam focusing system consists of quadrupole-doublet of the superconducting and permanent magnets. In this paper, the design progress of final focusing magnets is reported.
118969678
Tetraquark particle in the string model
We discuss the possibility of the existence of tetraquark states made of four quarks in the string (flux tube) model. The new particle is composed of a diquark and an antidiquark which are connected by a color flux. It is shown that the vibrational and rotational excited states of the string explain some non-qq mesons observed experimentally. Moreover we discuss the decay widths of such tetraquarks with the use of the Schwinger mechanism.