Two of the important goals of hadron physics are understanding of the degrees-of-freedom to describe the internal structure of hadrons and properties of hadrons in the finite density or temperature. ...The photon beam facilities have played important role for hadron physics. In this article, we review recent results on the study of few-body system in the hadron physics using photon beams.
Synopsis We investigate dtμe (= d + t + μ + e) four-body system which includes the most important bound states (dtμ)11 in muon catalyzed fusion (μCF). We directly estimate the energy shift more ...accurately than the previous perturbation calculation. The shift found to be one order of magnitude larger than previous calculation and to be more significant in the calculation of the μCF reaction rate.
We have constructed a new laser-Compton-scattering facility, called the LEPS2 beamline, at the 8 GeV electron storage ring, SPring-8. This facility provides a linearly polarized photon beam in a ...tagged energy range of 1.3–2.4 GeV. Thanks to a small divergence of the low-emittance storage-ring electrons, the tagged photon beam has a size (σ) suppressed to about 4 mm even after it travels about 130 m to the experimental building that is independent of the storage ring building and contains large detector systems. This beamline is designed to achieve a photon beam intensity higher than that of the first laser-Compton-scattering beamline at SPring-8 by adopting the simultaneous injection of up to four high-power laser beams and increasing a transmittance for the long photon-beam path up to about 77%. The new beamline is under operation for hadron photoproduction experiments.
The gamman-->K(+)K(-)n reaction on 12C has been studied by measuring both K+ and K- at forward angles. A sharp baryon resonance peak was observed at 1.54+/-0.01 GeV/c(2) with a width smaller than 25 ...MeV/c(2) and a Gaussian significance of 4.6sigma. The strangeness quantum number (S) of the baryon resonance is +1. It can be interpreted as a molecular meson-baryon resonance or alternatively as an exotic five-quark state (uuddsmacr;) that decays into a K+ and a neutron. The resonance is consistent with the lowest member of an antidecuplet of baryons predicted by the chiral soliton model.
A new GeV-photon beamline at SPring-8, LEPS II, has been constructed, and we have successfully observed the first beam at LEPS II in early 2013. The commissioning run using a photon detector has also ...started, and the detector development for a large solenoid magnetic spectrometer is underway. Physics motivations and the current status of LEPS II are described in this article.
Abstract
JSNS
$$^2$$
2
(J-PARC Sterile Neutrino Search at J-PARC Spallation Neutron Source) is an experiment that is searching for sterile neutrinos via the observation of
$${\bar{\nu }}_{\mu } ...\rightarrow {\bar{\nu }}_{e}$$
ν
¯
μ
→
ν
¯
e
appearance oscillations using muon decay-at-rest neutrinos. Before dedicated data taking in the first-half of 2021, we performed a commissioning run for 10 days in June 2020. Using the data obtained in this commissioning run, in this paper, we present an estimate of the correlated background which imitates the
$${\bar{\nu }}_{e}$$
ν
¯
e
signal in a sterile neutrino search. In addition, in order to demonstrate future prospects of the JSNS
$$^2$$
2
experiment, possible pulse shape discrimination improvements towards reducing cosmic ray induced fast neutron background are described.
SPring-8/LEPS is a GeV photon beam facility for hadron physics. The linearly polarized photon beam is produced by backward-Compton scattering of laser photons from 8 GeV electrons. We have studied ...photoproduction of hadrons which contain strange quarks. In this article, firstly, we report one of the recent results from LEPS, the κ(800) meson search in the γp → K*0Σ+ reaction. Secondly, the status of the construction of a new GeV photon beam line LEPS II is described.
The photo-production of ϕ mesons from Li, C, Al, and Cu at forward angles has been measured at Eγ=1.5–2.4GeV. The number of events for incoherent ϕ photo-production is found to have a target mass ...number dependence of A0.72±0.07 in the kinematical region of |t|⩽0.6GeV2/c2. The total cross section of the ϕ–nucleon interaction, σϕN, has been estimated as 35−11+17mb using the A-dependence of the ϕ photo-production yield and a Glauber-type multiple scattering theory. This value is much larger than σϕN in free space, suggesting that the ϕ properties might change in the nuclear medium.
Large strip RPCs for the LEPS2 TOF system Tomida, N.; Niiyama, M.; Ohnishi, H. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
12/2014, Letnik:
766
Journal Article
Recenzirano
Odprti dostop
High time-resolution resistive plate chambers (RPCs) with large-size readout strips are developed for the time-of-flight (TOF) detector system of the LEPS2 experiment at SPring-8. The experimental ...requirement is a 50-ps time resolution for a strip size larger than 100 cm super(2)/channel. We are able to achieve 50-ps time resolutions with 2.5100 cm super(2) strips by directly connecting the amplifiers to strips. With the same time resolution, the number of front-end electronics (FEE) is also reduced by signal addition.
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