A hyperon–nucleon scattering experiment, KEK-PS E289, was carried out at the K2 beam line in KEK. We adopted a scintillating fiber active target as a hydrogen target for hyperon production and ...subsequent hyperon–nucleon scattering. We collected more data than in a previous experiment, KEK-PS E251. In this paper, the differential cross sections for
Σ
+
p
elastic scattering in the incident momentum range from 350 to 750 MeV/
c are presented and compared with theoretical predictions from the Nijmegen group (Nijmegen Soft Core 97) and the Kyoto–Niigata group (RGM-FSS and fss2).
We performed an experiment to measure
γ rays of hyperfragments produced by stopped
K
−
reactions on light (
A
⩽
12
) targets (KEK-PS E509). We clearly observed an E2 transition (
5
/
2
+
→
1
/
2
+
) ...in
7
Λ
Li with
10B,
11B and
12C targets and obtained the
γ-ray intensity to be
(
7.5
±
1.6
)
×
10
−4
per stopped
K
−
for
10B target. In addition, a candidate for a new hypernuclear
γ ray was observed. These results show that this method is quite suitable for the systematic study of hypernuclei.
We measured γ rays of hyperfragments produced by stopped
K
− reactions on light (
A ≤ 12) targets (KEK-PS E509). By preliminary analysis, 2050 keV γ ray from
Λ
7Li(E2:
5
2
+
→
1
2
+
)
is seen with
...10B and C targets. Also, two candidates for new hypernuclear γ rays are observed.
Scintillating-fiber-block detectors have been constructed using
0.5
mm
square fibers for the KEK-PS E373 experiment, which searches for double-strangeness nuclei. The main aim of the detector is to ...measure the energies of protons and pions produced from decay of double- or single-hypernuclei using their ranges. It is also used to detect
Λ hyperons or the
H-dibaryon, and to make event selection. The performance of the detectors was studied with low-energy proton and pion beams as well as minimum-ionizing particles. The energy resolution determined by the range measurements was
0.86
MeV
for
37
MeV
π
−
's and
1.4
MeV
for
47
MeV
protons. The excellent capability of π/p separation has been also demonstrated.
An active target with scintillating fibers has been developed and constructed. This target-detector is designed for measurements of hyperon–proton scattering for hyperon momenta of several hundred
...MeV/c. The detector serves as a production target of hyperons as well as a hyperon scattering target on hydrogen. It works as a 4π-detector for the production, scattering, and decay of charged particles in the target region. A spectrometer system for an incident beam and outgoing particles is linked with this target-detector in order to produce triggers for the imaging device. Reactions inside the fiducial volume of the detector are reconstructed kinematically by using image data together with spectrometer information.
The present status of hypernuclear
γ-ray spectroscopy with Hyperball is summarized. We observed two
γ transitions of
16
Λ
O(
1
−
→
1
−
,
0
−
) and obtained the strength of the
ΛN tensor force. In
...10B(
K
−
,
π
−
γ
) data, we did not observe the spin-flip M1 transition of
10
Λ
B(
2
−
→
1
−
), but
γ rays from hyperfragments such as
7
Λ
Li(
7
/
2
+
→
5
/
2
+
) and
9
Λ
Be(
3
/
2
+
→
1
/
2
+
) were observed. In
11B(
π
+
,
K
+
γ
) data, we observed six
γ transitions of
11
Λ
B. We also attempted an inclusive
γ-ray measurement with a stopped
K
−
beam.
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