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A New measurement of the Pontecorvo reaction anti-p + d ---> pi- + p with the OBELIX spectrometer at LEAR

The OBELIX collaboration Ableev, V.G. ; Adamo, A. ; Agnello, M. ; et al.

Nucl.Phys.A 562 (1993) 617-643, 1993.

Inspire Record 364197 DOI 10.17182/hepdata.3849

Antinucleon-nucleus annihilations into two-body final states containing only one or no meson are unusual annihilations (Pontecorvo reactions), practically unexplored experimentally, with the exception of the channel p d → π − p , for which only two low-statistics measurements exist. Their physical interest lies in the possibility of exploring small-distance nuclear dynamics, in which an important role can be played by non-nucleonic degrees of freedom. A new measurement of the p d → π − p reaction rate at rest, performed with the OBELIX spectrometer at LEAR, with the best statistics up to now and a careful evaluation of systematic effects is reported, together with a critical analysis of the existing theoretical models. The measured branching ratio, which confirms the previous results, can represent a reference point for the studies in the field.

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Measurements of the anti-p d annihilation at rest

The OBELIX collaboration Ableev, V.G. ; Agnello, M. ; Balestra, F. ; et al.

Nucl.Phys.A 585 (1995) 577-617, 1995.

Inspire Record 401145 DOI 10.17182/hepdata.36534

The measurement of different reactions of p d annihilation at rest in a gaseous target has been performed using the OBELIX spectrometer at LEAR (CERN). A strong deviation from the OZI-rule prediction was found from the measurement of the ratio R = φπ ωπ in two regions of proton momenta, P < 200 MeV/ c and P > 400 MeV/ c : R( φπ − ωπ − ) = (133 ± 26) × 10 −3 and (113 ± 30) × 10 −3 , respectively. These values are about 30 times greater than the theoretical prediction. For the first time the excitation of the †-resonance was observed among the final-state products of p d annihilation. The existence of a broad enhancement in the 4π invariant mass at m ≈ 1480 MeV, seen in previous experiments, was confirmed. A ≈ 100 MeV downward shift of the bump position, when the proton momentum increased up to P > 400 MeV/ c , was also observed, while the positions of ω, ϱ and f 2 (1270) did not change with the proton momentum. The following branching ratios were measured: BR( p d → π − φ p ) = (6.62 ± 0.49) × 10 −4 , for P < 200 MeV/ c ; BR( p d → π − φ p ) = (0.95 ± 0.22) × 10 −4 , for P > 400 MeV/ c ; BR( p d → π − ω p ) = (49.7 ± 8.9) × 10 −4 , for P < 200 MeV/ c ; BR( p d → π − ω p ) = (8.38 ± 1.09) × 10 −4 , for P > 400 MeV/ c ; BR( p d → 2π − π + p ) = (150 ± 6) × 10 −4 , for P < 200 MeV/ c ; BR( p d → 2π − π + p ) = (16.6 ± 0.9) × 10 −4 , for P > 400 MeV/ c ; BR( p d → 3π − 2π + p ) = (326 ± 12) × 10 −4 , for P < 200 MeV/ c ; BR( p d → 3π − 2π + p ) = (44 ± 7) × 10 −4 , for P > 400 MeV/ c ; BR( p d → Λ K + π − ) = (0.96 ± 0.19) × 10 −4 , for P > 400 MeV/ c ; BR( p d → Λ K + π − π 0 ) = (3.5 ± 0.8) × 10 −4 , for P > 400 MeV/ c ; BR( p p → 2π − 2π + ) = (540 ± 20) × 10 −4 ; BR( p p → 3π − 3π + ) = (251 ± 21) × 10 −4 .

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Annihilation cross-sections of anti-neutrons on C, Al, Cu, Sn and Pb at low momenta (180-MeV/c - 280-MeV/c) with the OBELIX spectrometer

The OBELIX collaboration Ableev, V.G. ; Adamo, A. ; Agnello, M. ; et al.

Nuovo Cim.A 107 (1994) 943-953, 1994.

Inspire Record 384438 DOI 10.17182/hepdata.37841

Annihilation cross-sections σann for antineutrons on some nuclei (C, Al, Cu, Sn and Pb) at three antineutron momenta (180, 240 and 280 MeV/c) were measured at LEAR (CERN) with the OBELIX spectrometer. A behaviour σann=σ0Aν has been found withν≈2/3. The data are discussed following some models for antineutron-nucleus interaction.

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Investigation of the Charge Exchange Reaction ($^{3}$He, T) at 4.37-{GeV}/$c$, 6.78-{GeV}/$c$, and 10.78-{GeV}/$c$ With $\Delta$ Isobar Excitation in Carbon

Ableev, V.G. ; Eliseev, S.M. ; Inozemtsev, V.I. ; et al.

JETP Lett. 40 (1984) 763, 1984.

Inspire Record 204954 DOI 10.17182/hepdata.16928

None

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STUDY OF THE LEADING PROTON SPECTRA IN EXPERIMENTS ON 6.8-GEV/C PROTON SCATTERING ON PROTONS AND C, AL, CU, SN, PB NUCLEI. (IN RUSSIAN)

Ableev, V.G. ; Bodyagin, V.A. ; Vorobev, G.G. ; et al.

Yad.Fiz. 32 (1980) 1351-1356, 1980.

Inspire Record 159804 DOI 10.17182/hepdata.18015

None

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DATA ON THE SUM OF ELASTIC AND QUASIELASTIC CROSS SECTIONS.

Angular dependence of (He-3,t) charge-exchange cross sections on protons and carbon nuclei with excitation of the Delta isobar at momentum 6.91-GeV/c.

Ableev, V.G. ; Zaporozhets, S.A. ; Nomofilov, A.A. ; et al.

Sov.J.Nucl.Phys. 53 (1991) 286-291, 1991.

Inspire Record 330804 DOI 10.17182/hepdata.17254

None

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ALPHA NUCLEAR DIFFERENTIAL CROSS-SECTIONS AT 4.45-GeV/c PER NUCLEON

Ableev, V.G. ; Bodyagin, V.A. ; Vorobev, G.G. ; et al.

Acta Phys.Polon.B 16 (1985) 913-929, 1985.

Inspire Record 223292 DOI 10.17182/hepdata.51634

The absolute differential cross sections of 17.9 GeV/$c$ $\alpha$-particles scattering on nuclear targets have been measured over a four momentum transfer range of $0.009

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