Precision study of thedp→He3ηreaction for excess energies between 20 and 60 MeV

Measurements of branching ratios for η decays into charged particles

“…The reaction pd → 3 He η was used to produce η mesons at energies close to the production threshold, where the most favorable ratio between the η production cross section and background reactions is found. The cross section of this production reaction is 0.40(3) μb [ 3,4], meaning that up to eight events containing η mesons are produced per second at the peak luminosity of 2 × 10 31 cm −2 s −1 . The WASA detector is a fixed-target spectrometer, with a forward detector arranged to measure hadronic ejectiles and a central detector to detect light mesons or their decay products.…”

Search for η-mesic 3He in non-mesonic final state

“…[80] contains cross sections and angular distributions for the beam momentum values corresponding to Q3 Heη values of 13.6 MeV and higher. The earlier experiments [81][82][83] allow to assume that the angular distribution becomes symmetric with Q3 Heη going down to zero. Since the papers [81][82][83] contain only α parameter values, β and γ parameters extrapolation into Q3 Heη region below 13.6 MeV is needed ( Fig.…”

“…4.2). The cross section values are taken from [80,81] and linearly interpolated in our excess energy range ( Fig. 4.7).…”

“…4.1) because of pd → 3 Heη reaction. Its cross section [80][81][82][83] is about 300 nb in the Q3 Heη range [10; 30] M eV . Below the threshold, in case if the bound state is not observed, some count of background events is expected but essentially lesser than above the threshold.…”

The legacy of the experimental hadron physics programme at COSY

“…3), deduced from measurements of the pd → 3 He η differential cross section. These are shown as (black) circles [297], (blue) stars [293], and (red) triangles [294]. Only statistical errors are shown.…”