OBELIX
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Study of anti-n p --> phi pi+ and anti-n p --> omega pi+ annihilation reactions in flight.

The OBELIX collaboration Filippi, A. ; Agnello, M. ; Balestra, F. ; et al.
Nucl.Phys.A 655 (1999) 453-494, 1999.
Inspire Record 512679 DOI 10.17182/hepdata.36158

The results of a study of the annihilation reactions n p → θπ + and n p → ωπ + are reported; the data were collected by the OBELIX apparatus, with antineutrons annihilating in flight (momenta from ∼ 50 MeV/ c to 405 MeV/ c ). Annihilation frequencies and annihilation cross sections have been deduced, for both channels, as a function of antineutron momentum. From the cross section ratio, a substantial deviation from OZI rule expectations is observed. An s s quark content in the nucleon offers a fairly plausible explanation for such an effect.

2 data tables
Table 1

No description provided.

Table 2

No description provided.


Antineutron proton total cross section from 50-MeV/c to 400-MeV/c.

The OBELIX collaboration Iazzi, F. ; Feliciello, A. ; Agnello, M. ; et al.
Phys.Lett.B 475 (2000) 378-385, 2000.
Inspire Record 527242 DOI 10.17182/hepdata.28048

The antineutron–proton total cross section has been measured in the low momentum range 50–400 MeV/ c (below 100 MeV/ c for the first time). The measurement was performed at LEAR (CERN) by the OBELIX experiment, thanks to its unique antineutron beam facility. A thick target transmission technique has been used. The measured total cross section shows an anomalous behaviour below 100 MeV/ c . A dominance of the isospin I =0 channel over the I =1 one at low energy is clearly deduced.

1 data table
Table 1

Measured values of the total cross section.


Study of anti-neutron proton annihilation in two mesons in the momentum range between 50 to 400 MeV/c with OBELIX

The OBELIX collaboration Bertin, A. ; Bruschi, M. ; Capponi, M. ; et al.
Phys.Lett.B 410 (1997) 344-352, 1997.
Inspire Record 459313 DOI 10.17182/hepdata.28243

We measured the in flight annihilation frequencies and cross sections of reactions n p → π + π 0 ,π + η and K + K S in the antineutron momentum range between 50 and 400 MeV/c. The annihilation frequencies of these channels from the different allowed initial states were calculated and some information about the n p annihilation dynamics were obtained. The first determination of the D-wave contribution in this momentum range was also obtained.

1 data table
Table 1

No description provided.