arXiv subjects

M. I. Adamovich

Publications and source records attributed to M. I. Adamovich.

10 recordsLinked to original sources

arXiv2011

Interactions of Relativistic $^6$Li Nuclei with Photoemulsion Nuclei

Inelastic interactions of nuclei accelerated to a momentum of 4.5 GeV/$c$ per projectile nucleon with photoemulsion nuclei have been investigated. The main features of these interactions - mean ranges of $^6$Li nuclei, mean multiplicities of secondaries, the isotopic composition of fragments, fragmentation channels, and the mean transverse momenta of projectile fragments - have been measured. The probability of the charge-exchange reaction featuring lithium nuclei has been determined. The results obtained for the $^6$Li nucleus have been compared with data for other nuclei. The observed features of $^6$Li interactions with other nuclei indicate that the $^6$Li structure in the form of the loosely bound system consisting of an $α$-particle and a deuteron cluster clearly manifests itself in these interactions. Events resulting in the coherent dissociation of $^6$Li nuclei into $^4$He+$d$, $^3$He+$t$, and $t+d+p$ and involving low-lying excitations of $^6$Li have been observed.

nucl-ex↗

arXiv2011

Coherent Dissociation $^{16}$O~$\rightarrow$~4$α$ in Photoemulsion at an Incident Momentum of 4.5 GeV/$c$ per Nucleon

First searches for the coherent dissociation of relativistic oxygen nuclei into four a particles are reported. It is shown that reactions of this type are characterized by a significantly lower decay temperature than the conventional multifragmentation of residual projectile nuclei. The momentum spectra and correlations of a panicles are not reproduced by the simple statistical model of direct fragmentation. The possibility that the oxygen nucleus undergoing fragmentation acquires a nonzero angular momentum in the collision process is discussed.

nucl-ex↗

arXiv2007

Observation of a resonance in the K$_s$p decay channel at a mass of 1765 MeV/c$^2$

We report on the observation of a K$_s$p resonance signal at a mass of 1765$\pm$5 MeV/c$^2$, with intrinsic width $Γ= 108\pm 22$ MeV/c$^2$, produced inclusively in $Σ^-$-nucleus interactions at 340 GeV/c in the hyperon beam experiment WA89 at CERN. The signal was observed in the kinematic region $x_F>0.7$, in this region its production cross section rises approximately linearly with $(1-x_F)$, reaching $BR(X\to K_S p)\cdot dσ/dx_F = (5.2\pm 2.3) μb $ per nucleon at $x_F=0.8$. The hard \xf spectrum suggests the presence of a strong leading particle effect in the production and hence the identification as a $Σ^{*+}$ state. No corresponding peaks were observed in the $K^- p$ and $Λπ^{\pm}$ mass spectra.

hep-ex↗

arXiv2005

Search for the pentaquark candidate $Θ^+$(1540) in the hyperon beam experiment WA89

We report on a high-statistics search for the \t1540 resonance in $Σ^-$-nucleus collisions at 340 \gevc1 . No evidence for this resonance was found in our data sample which contains 13 millions $K^0_s \to π^+π^- $ decays above background. For the decay channel $Θ^+ \to K^0_s p$ and the kinematic range $x_F>$ 0.05 we find the production cross section to be $BR(Θ^+ \to K^0_s p)\cdot σ_0 <$ 1.8 $μ$b per nucleon at 99% CL.

hep-ex↗

arXiv2003

Investigation of Light Nucleus Clustering in Relativistic Multifragmentation Processes

The use of emulsions for studying nuclear clustering in light nucleus fragmentation processes at energies higher than 1A GeV is discussed. New results on the topologies of relativistic Li-7 and B-10 nucleus fragmentation in peripheral interactions are given. A program of research of the cluster structure in stable and radioactive nuclei is suggested.

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arXiv2002

Irradiation of nuclear emulsions in relativistic beams of He-6 and H-3 nuclei

Using a Li-6 nucleus beam extracted from the JINR Synchrophasotron at momentum 2.67A GeV/c a secondary beam was produced with a composition of 1% of He-6 and 99% of H-3 nuclei. Preliminary results on the features of nucleus-nucleus interactions of He-6 nuclei and charge exchange (CE) of H-3 nucleus are presented. Interactions of He-6 nucleus external neutrons with emulsion nuclei as well as a coherent stripping of He-6 nucleus external neutrons are observed. A mean range of H-3 nuclei to inelastic interactions in the BR-2 type emulsion is equal to 23.$\pm$3.0 cm. A mean range in emulsion for a nuclear CE process H-3 to He-3 is equal to 40$\pm$16 m. The CE cross-sections with a charged meson production or without it are approximately equal. The CE cross-section with excitation of a target nucleus exceeds the one without excitation. The mean transverse momentum of He-3 nuclei is equal to 0.16$\pm$0.03 GeV/c.

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arXiv1999

Determination of the total ccbar production cross section in 340 GeV/c Sigma- - nucleus interactions

The production of charmed particles by Sigma- of 340 Gev/c momentum was studied in the hyperon beam experiment WA89 at the CERN-SPS, using the Omega-spectrometer. In two data-taking periods in 1993 and 1994 an integrated luminosity of 1600 microb^-1 on copper and carbon targets was recorded. From the reconstruction of 930 +- 90 charm particle decays in 10 decay channels production cross sections for D, antiD, Ds and Lambdac were determined in the region xF>0. Assuming an A^1 dependence of the cross section on the nucleon number, we calculate a total ccbar production cross section of sigma(x_F > 0) = 5.3+- 0.4(stat)+-1.0(syst)+1.0(Xi_c) microb per nucleon. The last term is an upper limit on the unknown contribution from charmed-strange baryon production.

hep-ex↗

arXiv1997

First observation of the Xi- pi+ decay mode of the Xi0(1690) hyperon

We report the first observation of the Xi- pi+ decay mode of the Xi0(1690), confirming the existence of this resonance. The Xi0(1690) were produced by Sigma- of 345 Gev/c mean momentum in copper and carbon targets. The mass and width are close to those observed earlier for the Xi-(1690) in the Lambda K- decay channel. The product of inclusive production cross section and branching ratio is given relative to that of the Xi0(1530).

hep-ex↗

arXiv1997

Xi^- Production by Sigma^-, pi^- and Neutrons in the Hyperon Beam Experiment at CERN

Inclusive cross sections for Xi^- hyperon production in high-energy Sigma^-, pi^- and neutron induced interactions were measured by the experiment WA89 at CERN. Secondary Sigma^- and pi^- beams with average momenta of 345 GeV/c and a neutron beam of average momentum 65 GeV/c were produced by primary protons of 450 GeV/c from the CERN SPS. Both single and double differential cross sections are presented as a function of the transverse momentum and the Feynman variable x_F. A strong leading effect for Xi^- produced by Sigma^- is observed. The influence of the target mass on the Xi^- cross section is explored by comparing reactions on copper and carbon nuclei.

hep-ex↗

arXiv1994

Measurement of the polarization of Lambda0 AntiLambda0, Sigma+ and Xi- produced in a Sigma- beam of 330 GeV/c

The polarization of Lambda0, AntiLambda0, Sigma+ and Xi- inclusively produced in Sigma- induced interactions at 330 GeV has been measured in the experiment WA89 at CERN. This is the first measurement of polarization of baryons produced by a hyperon beam. No polarization of AntiLambda is observed, as was also the case in proton beam data. At transverse momenta of about 1 GeV/c Lambda0 and Sigma+ show little polarization, significantly lower than in the proton beam data, while Xi- have a polarization comparable to the polarization of Lambda0 produced in proton beams.

hep-ex↗