Yu. A. Batusov

Low-energy Antiproton Neon Interaction

Abstract By means of a streamer chamber exposed to the LEAR antiproton beams, the total reaction cross sections, the charged-prong multiplicity distributions and lower limits for the production of negative pions and K s 0 in the p-Ne interaction were measured at 19.6, 48.7 and 179.6 MeV. Annihilation was found to be dominant over all other non-elastic p-Ne processes. An analysis of Ne and other nuclei data in the frame of the Glauber theory allowed us to determine the ratio between the p-n and the p-p cross sections. An analysis in the light of INC model predictions allowed us to show up events which can be interpreted as annihilations having occurred deeply inside the nuclei.

Inelastic interaction of antiprotons with 4He nuclei between 200 and 600 MeV/c

The antiproton-helium reaction cross section has been measured at 19.6 and 48.7 MeV with a streamer chamber in a magnetic field. Charged prongs and negative pion multiplicities and cross sections for the production of 3He are given. A comparison with p 2H is performed. he previously obtained 179.6 MeV results are also taken into account.

Determination of the ratio σ(p̄n)/σ(p̄p) from p̄4He reaction data

Abstract The ratio R a b between the cross sections for the annihilation of p on n and on p bound in the 4 He nucleus at four p momenta (at rest, 192.8, 306.2 and 607.7 MeV/ c ) has been obtained by the analysis of p 4 He annihilation events detected with a self-shunted streamer chamber exposed to the LEAR p beams. R a b increases from 0.42 ± 0.05 at rest up to 0.66 ± 0.09 at 607.7 MeV/ c . The results are discussed in the light of Glauber theory analyses of p 2 H and p -nucleus data.

Experimental apparatus for studying the interaction of antiprotons with light nuclei

Abstract A description is given of the detector system (self-shunted streamer chamber in a magnetic field) used in the PS-179 experiment at LEAR for studying antiproton interactions with light nuclei.

Neutral strange-particle production in p̄20Ne reactions at 607 MeV/c

Abstract The Λ 0 and K 0 s production cross sections have been measured at 607 MeV/ c for the reaction p + 20 Ne → V 0 + X ( V 0 =Λ, 0 , K 0 s ) . The Λ 0 /K 0 s production ratio is found to be (2.3±0.7). The data are consistent with an evaporative character of the emission mechanism from a multinucleon system for Λ 0 and from one nucleon for K 0 s . The rapidity distributions of negative tracks in K 0 x events are different from those in Λ 0 events without V 0 .

p4He reaction cross section at 610 MeV/c

Abstract Antiproton helium reaction cross section has been measured at 179.6 MeV with a self shunted streamer chamber in a magnetic field. Charged prong multiplicity, branching ratios and 3He production probability are given. Comparison with p 2 H data is performed.

Limits on neutral light scalar and pseudoscalar particles in a proton beam dump experiment

A search has been performed for weakly interacting neutral light scalar and pseudoscalar particles in a proton beam dump experiment. No positive signal is observed. Limits on the mass and life-time of these particles are set in the frame of the Standard Model and its minimal supersymmetric extension. The Higgs particle of theSU2L×U1 Standard Theory is excluded for masses in the range 1 MeV<mH<80 MeV at 95%CL. Limits on the Peccei-Quinn like axions are derived.

Antiproton-helium annihilation around 45 MeV/c

Abstract The p ¯ 4 He annihilation cross section averaged over the interval 40–50 MeV/c has been measured using a streamer chamber in a magnetic field. The measured value is 1342±250 mb. It agrees with a behaviour like 1/p of the annihilation cross section. Our result has been obtained at the lowest momentum achieved till now in measurements of antiproton annihilation in flight.

Strangeness production in antiproton annihilation at rest on 3He, 4He and 20Ne

Abstract New data are reported on antiproton annihilations at rest with production of Λ and K s 0 , using a streamer chamber with 3 He, 4 He and 20 Ne as gas targets. The data include Λ, K s 0 , ΛK s 0 and K s 0 K S 0 production rates and momentum distributions, π − momentum spectra, mean numbers of charged particles generally and of negatively charged particles separately for different reaction channels. The yields are compared to simple combinatorial calculations based on the extreme assumptions of Λ production via B = 1 or via B = 0 ( K rescattering) annihilations. Λ and K s 0 momentum spectra are compared to simple model calculations where B = 0 and B = 1 annihilations with and without final-state interactions are considered. A review of existing data on Λ and K s 0 production is presented, showing the dependence on the p momentum and on the mass number of the target.

Search for heavy neutrinos at the IHEP-JINR neutrino detector

Abstract Data from a proton beam-dump experiment at the 70 GeV Serpukhov accelerator were analysed to search for heavy neutrino decays ν H → e + e − ν e at the IHEP-JINR Neutrino Detector. No signal over background was found. The upper limits on the elements if a mixing matrix | U eH | 2 in the mass range 5 m νH U eH || U μH | in the mass range 3 m νH