A study of the double hadron neutrino production on nuclei

The nuclear medium influence on the dihadron neutrino charged current production is investigated using the data obtained with SKAT bubble chamber. An indication is obtained that the nuclear attenuation of the dihadron production is more expressed for kinematically closest hadron pairs. The experimental data are compared with predictions of the string model.     

Measurement of the yields of positively charged particles at an angle of 35° in proton interactions with nuclear targets at an energy of 50 GeV

Momentum spectra of cumulative particles in the region of high transverse momenta (P _T ) in pA → h ⁺ + X reactions were obtained for the first time. The experiment in which this was done was performed at the SPIN setup (Institute for High Energy Physics, Protvino) in a beam of 50-GeV protons interacting with C, Al, Cu, and W nuclei. Positively charged particles were detected at a laboratory angle of 35° and in the transverse-momentum range between 0.6 and 3.7 GeV/c. A strong dependence of the particle-production cross section on the atomic number was observed. A comparison with the results of calculations based on the HIJING and UrQMD models was performed in the subcumulative region.     

The yields of light meson resonances in neutrino-nucleus interactions at 〈<Emphasis Type="Italic">E</Emphasis><Subscript><Emphasis Type="Italic">ν</Emphasis></Subscript>〉≈ 10 GeV

The nuclear medium influence on the dihadron neutrino charged current production is investigated using the data obtained with SKAT bubble chamber. An indication is obtained that the nuclear attenuation of the dihadron production is more expressed for kinematically closest hadron pairs. The experimental data are compared with predictions of the string model.     

HARP–CDP hadroproduction data: comparison with FLUKA and GEANT4 simulations

We report on the comparison of production characteristics of secondary protons and charged pions in the interactions of protons and charged pions with momentum between 3 GeV/c and 15 GeV/c with beryllium, copper, and tantalum nuclei, with simulations by the FLUKA program and the Geant4 tool kit. Overall production cross-sections are reasonably well reproduced, within factors of two. In more detail, there are areas with poor agreement that are unsatisfactory and call for modelling improvements. Overall, the current FLUKA simulation fares better than the current Geant4 simulation.     

A study ofv e −v μ universality and search for neutrino oscillations

In the SKAT neutrino bubble chamber experiment at the Serpukhov accelerator we observe 83 events with electrons and no further lepton in the final state. Comparing the ratio of electron to muon charged current events at energies 3<E _v <30 GeV with that expected fromv _e -beam background assuming lepton universality we find \(R = (N_{e^ - } /N_{\mu ^ - } )_{\exp } /(N_{e^ - } /N_{\mu ^ - } )_{calc} = 0.98 \pm 0.15\) . Furthermore we compare experimental observations and theoretical expectations for some differential distributions of the electron-neutrino charged current reaction. No significant deviation from lepton universality is found. Looking in the charged current reaction for oscillations of muon to electron type neutrinos we find no effect down to the 90% confidence limits Δm ² =1.3 eV² at sin²2θ=1 and sin²2θ=2.5·10^?3 at Δm ²=60 eV².     

Neutrino production of charmed particles in a hybrid experiment E-564

Cryogenically sensitive nuclear emulsion was placed inside the 15-foot bubble chamber of FNAL and exposed to a wide-band energy (up to 200 GeV) neutrino beam. 194 charged-current neutrino interactions and 13 decays of charmed particles were registered. Using the nuclear emulsion as a vertex detector with the good spectrometric properties of the 15-foot bubble chamber has allowed the decays of charmed particles to be effectively analysed. Attentions is focussed on the new physical results. Λ _c ⁺ baryon andD _s ⁺ meson decay channels, production of charmed ∑ _c baryons and Λ _c ⁺ via ∑ _c . For the first time an event interpreted as production of the excited (c \(\overline s\) )-state with mass ～2790 MeV/c² has been registered.     

Comments on “Measurement of the production of charged pions by protons on a tantalum target”

We argue that the cross-sections reported in the article “Measurement of the production of charged pions by protons on a tantalum target” by M.G. Catanesi et al., published in this journal, result from invalid analysis concepts and should not be trusted. PACS 13.85.Ni; 25.40.Ep     

Photon production in 69 GeV pp interactions

We present results on 728 photon conversions into electron pairs observed in the hydrogen bubble chamber MIRABELLE. The average number of π° per inelastic pp collision is found to be 2.57 ± 0.13 and this number increases with the number n of charged particles up to n=12. The comparison of our invariant cross section F(x, p⊥, s) for the reaction pp → γ X with higher energy results shows that scaling behaviour is probably reached at 70 GeV.     

Measurement of the tensor structure function b1 of the deuteron

The Hermes experiment has investigated the tensor spin structure of the deuteron using the 27.6 GeV/c positron beam of DESY HERA. The use of a tensor-polarized deuteron gas target with only a negligible residual vector polarization enabled the first measurement of the tensor asymmetry A(d)zz and the tensor structure function b(d)1 for average values of the Bjorken variable 0.01< <0.45 and of the negative of the squared four-momentum transfer 0.5 GeV2 < <5 GeV2. The quantities A(d)zz and b(d)1 are found to be nonzero. The rise of b(d)1 for decreasing values of x can be interpreted to originate from the same mechanism that leads to nuclear shadowing in unpolarized scattering.     

Q2 dependence of nuclear transparency for exclusive rho0 production

Exclusive coherent and incoherent electroproduction of the rho(0) meson from 1H and 14N targets has been studied at the HERMES experiment as a function of coherence length (l(c)), corresponding to the lifetime of hadronic fluctuations of the virtual photon, and squared four-momentum of the virtual photon (-Q2). The ratio of 14N to 1H cross sections per nucleon, called nuclear transparency, was found to increase (decrease) with increasing l(c) for coherent (incoherent) rho(0) electroproduction. For fixed l(c), a rise of nuclear transparency with Q2 is observed for both coherent and incoherent rho(0) production, which is in agreement with theoretical calculations of color transparency.