arXiv subjects

N. Grigoryan

Publications and source records attributed to N. Grigoryan.

15 recordsLinked to original sources

arXiv2019

Decay pion spectroscopy: a new approach

We propose a new experiment for decay pion spectroscopy of light hypernuclei at electron- and proton-beam facilities, using the recoil distance technique for separation of produced hypernuclei and a magnetic spectrometer for precise measurement of the decay pion momentum. Low-pressure MWPCs are advocated for low-energy recoil detection as they provide position and time information and are highly insensitive to gamma-ray and electron background. The position and timing characteristics of such a recoil detector were studied using ~5 MeV α-particles. By using the present proposed approach the rate of the detected hypernuclei can be increased by one-to-two orders of magnitude compared to a recent experiment carried out at the MAMI electron accelerator in Mainz. The possibility of realizing a high luminosity decay pion spectroscopy experiment with proton beams is also discussed.

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arXiv2013

The yields of different states of Delta(1232) in neutrino-induced reactions at E_ν= 10 GeV

First experimental data on the inclusive yields of Delta^{0}(1232) and Delta^{+}(1232) isobars in neutrino-induced reactions are obtained. Their total yields in neutrino-nucleon interactions, 0.145+-0.055 and 0.182+-0.054, respectively, exceed the value of 0.091+-0.015 obtained recently for the Delta^{++}(1232) state. The data for the all three states of Delta(1232) cannot be reproduced by the LEPTO6.5 model. The fractions of π^0, π^- and π^+ mesons originating from the decay of lightest baryonic and mesonic resonances are estimated to be, respectively 56.6+-9.6%, 39.5+-6.6% and 27.7+-3.2%.

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arXiv2013

Study of nuclear effects in the inclusive neutrinoproduction of the δ^{++}(1232) isobar

For the first time, the inclusive neutrinoproduction of Δ^{++}(1232) from nuclei is investigated. The total yield of $Δ^{++}(1232) in neutrino-nuclear interaction is found to be \ < n\ >_{νA} = 0.080\pm0.011, being compatible with \ < n\ >_{νN} = 0.091\pm0.013 inferred for neutrino-nucleon interactions. It is shown that the Δ^{++}(1232) inclusive spectra on variables x_F, z and the isobar total momentum for νA interactions are shifted toward lower values respective to those for νN interactions, that can be caused by secondary intranuclear collision processes. No idication on a significant nuclear absorption of Δ^{++}(1232) leading to its disappearance is found.

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arXiv2012

Study of the delta^{++}(1232) inclusive neutrinoproduction on protons and neutrons

For the first time, the total yield and inclusive spectra of the $Δ^{++}(1232)$isobar are measured in $νp$ and $νn$ charged-current interactions. An indication is obtained that the $Δ^{++}(1232)$ production mainly results from the neutrino scattering on the valence d- quark of the target nucleon. The total yield of $Δ^{++}(1232)$ in $νp$ interactions is compatible with that measured in hadronic interactions of the same net charge and net baryonic number. The yield of $Δ^{++}(1232)$ in $νn$ interactions is significantly suppressed as compared to the case of the proton target. The form of the squared transverse momentum distributions, both in $νp$ and $νn$ interactions, is found to be compatible with the available data on the neutrinoproduction of $Λ$ hyperon. The experimental data are compared with the LEPTO6.5 model predictions.

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arXiv2011

Nuclear attenuation of three-hadron systems in neutrino-induced reactions

For the first time, the nuclear attenuation of three hadron systems is studied in neutrino-induced reactions using the data obtained with SKAT bubble chamber. The strongest attenuation (R_3 ~ 0.6) is observed for a system carrying an overwhelming fraction of the current quark energy, as well as for a system with the smallest effective mass. An indication is obtained that the correlation effects in the nuclear attenuation play only a minor role. The experimental data are compared with predictions of the quark string fragmentation model.

hep-ex↗

arXiv2011

Nuclear effects in Reactions νp -> μ^- p π^+ and νp -> μ^- Δ^{++}(1232) on Bound Protons

For the first time, the nuclear effects in the reaction νp -> μ^- p π^+ on bound protons are investigated at E_ν= 9 GeV and the effective atomicweight A = 21 of the composite nuclear target using the data obtained with SKAT bubble chamber. The observed nuclear effects are explained by the Fermi-motion of the target proton and secondary elastic scattering of neutrinoproduced hadrons on intranuclear neutrons. The probability of any intranuclear interaction of neutrinoproduced hadrons is extracted: P_int = 0.40+-0.13, while the probability of interactions occurring only via elastic scattering on intranuclear neutrons is estimated to be P_c = 0.14+-0.05. A clear evidence of the Δ^{++}(1232) and an indication on the Δ^{++}(1620) isobar states production are observed with the mean yields, respectively, 0.57+-0.09 and 0.40+-0.26 (the latter being corrected for the p π^+ decay fraction). The mean yield of Δ^{++}(1232) is by 1.61+-0.25 times smaller than expected for the reaction on the hydrogen target, thus indicating on its rather strong nuclear absorption.

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arXiv2009

A study of the neutrinoproduction of Phi and D_s^+ mesons

The neutrinoproduction of $ϕ$ and $D^+_s$ mesons is studied, using the data obtained with the SKAT bubble chamber at the Serpukhov accelerator. It is found that the $ϕ$ production occurs predominantly in the forward hemisphere of the hadronic c.m.s. (at $x_F > 0$, $x_F$ being the Feynman variable), with the mean yield strongly exceeding the expected yield of directly produced $ϕ$ mesons and varying from $ 0) > = (0.92\pm0.34) \cdot 10^{-2}$ at $W > $ 2 GeV up to $(1.23\pm0.53) \cdot 10^{-2}$ at $W >$ 2.6 GeV and $(1.44\pm0.69) \cdot 10^{-2}$ at $W >$ 2.9 GeV, $W$ being the invariant mass of the hadronic system. The yield of leading $D^+_s$ mesons carrying more than $z = 0.85$ of the current $c$- quark energy is estimated: at $W > 2.9$ GeV, $ 0.85) > = (6.64\pm1.91) \cdot 10^{-2}$. It is shown, that the shape of the $ϕ$ meson differential spectrum on $x_F$ is reproduced by that expected from the $D^+_s \to ϕX$ decays which, however, can account for only the half of the measured $ϕ$ yield.

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arXiv2008

The yields of light meson resonances in neutrinonuclear interactions at = 10 GeV

The total yields of the all well-established light mesonic resonances (up to the $ϕ$(1020) meson) are estimated in neutrinonuclear interactions at < E_nu > = 10 GeV, using the data obtained with SKAT bubble chamber. For some resonances, the yields in the forward and backward hemispheres in the hadronic c.m.s. are also extracted. From the comparison of the obtained and available higher-energy data, an indication is obtained that the resonance yields rise almost linearly as a function of the mean mass < W > of the neutrinoproduced hadronic system. The fractions of pions originating from the light resonance decays are inferred.

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arXiv2008

Charged rho meson production in neutrino-induced reactions at E_nu = 10 GeV

The neutrinoproduction of charged $ρ$ mesons on nuclei and nucleons is investigated for the first time at moderate energies ($ \approx$ 10 GeV), using the date obtained with SKAT bubble chamber. No strong nuclear effects are observed in $ρ^+$ and $ρ^-$ production. The fractions of charged and neutral pions originating from $ρ$ decays are obtained and compared with higher energy data. From analysis of the obtained and available data on $ρ^+$ and $K^{*+}$(892) neutrinoproduction, the strangeness suppression factor in the quark string fragmentation is extracted: $λ_s = 0.18\pm0.03$. Estimations are obtained for cross sections of quasiexclusive single $ρ^+$ and coherent $ρ^+$ neutrinoproduction on nuclei. The estimated coherent cross section $σ_{ρ^+}^{coh}$ = (0.29$\pm0.16)\cdot 10^{-38}$ cm$^2$ is compatible with theoretical predictions.

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arXiv2006

A study of the double hadron neutrinoproduction on nuclei

The nuclear medium influence on the dihadron neutrinoproduction is investigated for the first time, using the data obtained with SKAT bubble chamber. An indication is obtained that the nuclear attenuation of the dihadron is more expressed for kinematically closest hadron pairs. The experimental data on the dihadron attenuation and on the ratio of the dihadron to single-hadron yields are compared with predictions of the two-scale string fragmentation model.

hep-ex↗

arXiv2005

The A - dependence of rho^0 neutrinoproduction on nuclei

The A - dependence of rho^0 meson production in neutrino-induced reactions is investigated for the first time, using the data obtained with SKAT bubble chamber. The nuclear medium influence on the rho^0 total yield and inclusive distributions (on z = E_rho/nu and Feynman x_F variables) is found to be approximately the same as for pions. It is shown, that these distributions, with increasing A, tend to shift toward smaller values of z and x_F, thus indicating on an increasing role of secondary intranuclear interactions. The predictions of a simplified model incorporating the latter are found to be in qualitative agreement with experimental data.

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arXiv2005

The total yields of K^+(892), Sigma^+(1385) and Sigma^0 in neutrino-induced reactions at = 10 GeV

Using the data obtained with SKAT bubble chamber, the total yields of $K^+(892)$, $Σ^+(1385)$ and $Σ^0$ are estimated for the first time in neutrino-induced reactions at moderate energies ($ $ = 10.4 GeV). It is shown, that the recently observed \cite{ref1,ref2} enhancement of the $K^0$ and $Λ$ yields in $νA$ interactions (as compared to $νN$ interactions) is contributed only slightly by the $K^+(892)$ and $Σ^+(1385)$ production, respectively. The decay contribution to the $K^0$ and $Λ$ yields is found to be in qualitative agreement with higher energy ($ \geq$ 40 GeV) data. It is shown, that the energy dependence of the $K^+(892)$ mean multiplicity in $νN$ interactions is approximately linear in the range of $ \approx$ 10-60 GeV, while that for $Σ^0$ in $νA$ interactions (for $A$ = 20-21) is approximately logarithmic in the range of $ \approx$ 10-150 GeV.

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arXiv2005

The A - dependence of $K^{0}$ and $Λ$ neutrinoproduction on nuclei

For the first time, the A- dependence of the production of $K^0$, $Λ$ and, for comparison, $π^-$ mesons is investigated in neutrinonuclear reactions, using the data obtained with SKAT bubble chamber. An exponential parametrization ($\sim A^β$) of the particle yields results in $β_{V^0} = 0.20 \pm 0.05$ for $V^0$ particles (combined $K^0$ and $Λ$), while for $π^-$ mesons the A- dependence is much weaker, $β_{π^-} = 0.068 \pm 0.007$. A nuclear enhancement of the ratio $K^0/π^-$ is found; this ratio increases from $0.055 \pm 0.013$ for $νN$- interactions up to $0.070 \pm 0.011$ at $A \approx 21$ and $0.099 \pm 0.011$ at $A \approx 45$. It is observed, that the multiplicity rise of $V^0$'s occures predominantely in the backward hemisphere of the hadronic c.m.s. It is shown, that the A- dependence of the nuclear enhancement of the $Λ^0$ and $π^-$ yields can be reproduced in the framework of a model, incorporating the secondary intranuclear interactions of pions originating from the primary $νN$- interactions, while only (29$\pm$9)% of that for $K^0$ at $A \approx 45$ can be attributed to intranuclear interactions.

hep-ex↗

arXiv2004

The characteristics of neutrinonuclear reactions at E_nu = 1 - 3 GeV

For the first time, the characteristics of the charged current neutrinonuclear interactions are investigated at $E_ν$ = 1 - 3 GeV using the data obtained with SKAT propane-freon bubble chamber irradiated in the neutrino beam at Serpukhov accelerator. The $E_ν$ - dependence of the mean multiplicities of different types of secondary particles and their multiplicity, momentum and angular distributions are measured.

hep-ex↗

arXiv2003

A study of the nuclear medium influence on transverse momentum of hadrons produced in deep inelastic neutrino scattering

The influence of nuclear effects on the transverse momentum $(p_T)$ distributions of neutrinoproduced hadrons is investigated using the data obtained with SKAT propane-freon bubble chamber irradiated in the neutrino beam (with $E_ν$ = 3-30 GeV) at Serpukhov accelerator. Dependences of $ $ on the kinematical variables of inclusive deep-inelastic scattering and of the produced hadrons are measured. It has been observed, that the nuclear effects cause an enhancement of $ $ of hadrons (more pronounced for the positively charged ones) produced in the target fragmentation region at low invariant mass of the hadronic system (2 $< W <$ 4 GeV) or at low energies transferred to the current quark (2 $< ν< 9$ GeV). At higher $W$ or $ν$, no influence of nuclear effects on $ $ is observed. Measurement results are compared with predictions of a simple model, incorporating secondary intranuclear interactions of hadrons (with a formation length extracted from the Lund fragmentation model), which qualitatively reproduces the main features of the data.

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