A new hyperon-proton scattering experiment, dubbed J-PARC E40, was performed to measure differential cross sections of the Σ
+
p
, Σ
−
p
elastic scatterings and the Σ
−
p
→ Λ
n
scattering by ...identifying a lot of Σ particles in the momentum ranging from 0.4 to 0.8 GeV/
c
produced by the
π
±
p
→
K
+
Σ
±
reactions. We successfully measured the differential cross sections of these three channels with a drastically improved accuracy with a fine angular step. These new data will become important experimental constraints to improve the theories of the two-body baryon-baryon interactions. Following this success, we proposed a new experiment to measure the differential cross sections and spin observables by using a highly polarized Λ beam for providing quantitative information on the Λ
N
interaction. The results of three Σ
p
channels and future prospects of the Λ
p
scattering experiment are described.
The article is devoted to the creation of an experimental SRP-STRAW installation manufacturing unique STRAW detectors for the joint JINR-KEK experiment COMET. The method of welding straw tubes ...applying ultrasound greatly simplifies the technology of their production compared to the case of twisted tubes made by spiral winding and gluing two layers of mylar. The amount of matter decreases, which is important to minimize multiple scattering. The reduction of multiple scattering is also facilitated by a decrease in the level of gas leakage from the tubes. The measured parameters of the tubes showed the high quality of their production and reliability.
NEXT is an experiment dedicated to neutrinoless double beta decay searches in xenon. The detector is a TPC, holding 100 kg of high-pressure xenon enriched in the 136Xe isotope. It is under ...construction in the Laboratorio Subterráneo de Canfranc in Spain, and it will begin operations in 2015. The NEXT detector concept provides an energy resolutionbetter than 1% FWHM and a topological signal that can be used to reduce the background. Furthermore, the NEXT technology can be extrapolated to a 1 ton-scale experiment.
A high statistics ∑p scattering experiment has been performed at the K1.8 beamline in the J-PARC Hadron Experimental Facility. Data for momentum-tagged ∑− beam running in a liquid hydrogen target ...were accumulated by detecting the π−p→K+∑− reaction with a high intensity π− beam of 20 M/spill. The number of the Σ− beam was about 1.7 × 107 in total. The ∑−ρ elastic scattering and the ∑−p → Λn inelastic scattering events were successfully observed with about 100 times larger statistics than that in past experiments.
The Θ(+) pentaquark baryon was searched for via the π(-)p→K(-)X reaction with a missing mass resolution of 1.4 MeV/c(2) (FWHM) at the Japan Proton Accelerator Research Complex (J-PARC). π(-) meson ...beams were incident on the liquid hydrogen target with a beam momentum of 1.92 GeV/c. No peak structure corresponding to the Θ(+) mass was observed. The upper limit of the production cross section averaged over the scattering angle of 2° to 15° in the laboratory frame is obtained to be 0.26 μb/sr in the mass region of 1.51-1.55 GeV/c(2). The upper limit of the Θ(+) decay width is obtained to be 0.72 and 3.1 MeV for J(Θ)(P)=1/2(+) and J(Θ)(P)=1/2(-), respectively, using the effective Lagrangian approach.
High-sensitivity double-gap phenolic resistive plate chambers (RPCs) are studied for the Phase-2 upgrade of the Compact Muon Solenoid (CMS) muon system at high pseudorapidity
η
. Whereas the present ...CMS RPCs have a gas gap thickness of 2 mm, we propose to use thinner gas gaps, which will improve the performance of these RPCs. To validate this proposal, we constructed double-gap RPCs with two different gap thicknesses of 1.2 and 1.4 mm by using high-pressure laminated plates having a mean resistivity of about 5 × 10
10
Ω-cm. This paper presents test results using cosmic muons and
137
Cs gamma rays. The rate capabilities of these thin-gap RPCs measured with the gamma source exceed the maximum rate expected in the new high-
η
endcap RPCs planned for future Phase-2 runs of the Large Hadron Collider (LHC).
Experimental results on pion decays obtained with the PIBETA spectrometer at the Paul Scherrer Institute (PSI) are reviewed. For pion beta decay π
+
→ π
0
е
+
ν (πβ), a precision measurement of ...relative probability yields Г(πβ) = 1.036 ± 0.004(stat) ± 0.004(syst) ± 0.003(π
+
→е
+
ν) × 10
–8
, which implies
V
ud
= 0.9728(30) for the corresponding element of the Cabibbo–Kobayashi–Maskawa mixing matrix. Using a sample of 65 × 10
3
events, relative probability of the π
+
→е
+
νγ radiative pion decay (RPD) in the kinematic region of
E
γ
> 10 MeV and
θ
eγ
> 40° is measured as
B
exp
= 73.86(54) × 10
–8
. A statistical analysis of measured
E
e
+
and
E
γ
distributions for this decay yield the values
F
V
= 0.0258(17) and
F
A
= 0.0117(17) for the pion weak formfactors. Assuming that
F
V
linearly depends on the е
+
ν invariant mass
q
2
as
F
V
(
q
2
) =
F
V
(0)(1 +
aq
2
), the slope parameter is extracted as
а
= 0.10(6). The pion polarizability and neutral-pion lifetime are estimated as
α
E
= 2.78(10) × 10
–4
fm
3
and τ(π
0
) = (8.5 ± 1.1) × 10
–17
s, respectively. The data for decays π
+
→ е
+
ν and
μ
+
→
e
+
v
v
¯
γ
have been collected and are being processed. The follow-up PEN experiment aims at reducing the uncertainty on the π
+
→ е
+
ν relative probability by almost an order of magnitude (to 5 × 10
–4
).
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