-
M.I. Adamovich,
Y.A. Alexandrov,
S.P. Baranov,
D. Barberis,
M. Beck,
C. Bérat,
W. Beusch,
M. Boss,
S. Brons,
W. Brückner, [......],
A. Trombini,
E. Vesin,
B. Volkemer,
K. Vorwalter,
T. Walcher,
G. Wälder,
R. Werding,
E. Wittmann,
M.V. Zavertyaev,
The Collaboration
[show abstract]
[hide abstract]
ABSTRACT: We report on the observation of a KSp resonance signal at a mass of 1765 ± 5MeV/c
2, with intrinsic width Γ = 108 ± 22MeV/c
2, produced inclusively in Σ--nucleus interactions at 340GeV/c in the hyperon beam experiment WA89 at CERN. The signal was observed in the kinematic region xF>0.7, in this region its production cross section rises approximately linearly with (1-xF), reaching BR(X→KSp)dσ/dxF=(5.2±2.3)μb per nucleon at xF=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± mass spectra.
European Physical Journal C 04/2012; 50(3):535-538. · 3.63 Impact Factor
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M.I. Adamovich,
Yu.A. Alexandrov,
S.P. Baranov,
D. Barberis,
M. Beck,
C. Bérat,
W. Beusch,
M. Boss,
S. Brons,
W. Brückner, [......],
A. Trombini,
E. Vesin,
B. Volkemer,
K. Vorwalter,
T. Walcher,
G. Wälder,
R. Werding,
E. Wittmann,
M.V. Zavertyaev,
The Collaboration
[show abstract]
[hide abstract]
ABSTRACT: We present a comprehensive study of the inclusive production of V0V0 pairs (V0=Λ, Λ̄ or KS ) by Σ- and π- of 340GeV/c momentum and neutrons of 260GeV/c mean momentum in copper and carbon targets. In particular, the dependence of the xF spectra on the combination of beam-particle and produced V0V0 pair is investigated and compared to predictions obtained from PYTHIA and QSGM calculations. The data and these predictions
differ in many details, the agreement can at best be termed as qualitative. A signal from decays of the tensor meson f’2(1525) was observed in the KS KS mass distribution and inclusive production cross sections were measured. No signal was found from the double-strange H-dibaryon
decaying to ΛΛ.
European Physical Journal C 11/2007; 52(4):857-874. · 3.63 Impact Factor
-
E S Ageev,
V Yu Alexakhin,
Y. Alexandrov,
G D Alexeev,
A Amoroso,
B Badelek,
F Balestra,
J Ball,
G Baum,
Y Bedfer, [......],
U Wiedner,
M Wiesmann,
R Windmolders,
S Wirth,
W Wilicki,
A M Zanetti,
K Zaremba,
J Zhao,
R Ziegler,
A. Zvyagin
[show abstract]
[hide abstract]
ABSTRACT: We present a precise measurement of the deuteron longitudinal spin asymmetry $A_1^d$ and of the deuteron spin-dependent structure function $g_1^d$ at $Q^2 < $ 1~(GeV/$c$)$^2$ and $4\cdot$10$^{-5} < x < $~2.5$\cdot$10$^{-2}$ based on the data collected by the COMPASS experiment at CERN during the years 2002 and 2003. The statistical precision is tenfold better than that of the previous measurement in this region. The measured $A_1^d$ and $g_1^d$ are found to be consistent with zero in the whole range of $x$.
Physics Letters B 04/2007; 647(5-6):330-340. · 3.95 Impact Factor
-
WA89 Collaboration,
M I Adamovich,
Yu A Alexandrov,
D Barberis,
M Beck,
C Bérat,
W. Beusch,
M Boss,
S. Brons,
W Brückner, [......],
O Thilmann,
A Trombini,
E Vesin,
B Volkemer,
K Vorwalter,
Th. Walcher,
G Wälder,
R Werding,
E Wittmann,
M V Zavertyaev
[show abstract]
[hide abstract]
ABSTRACT: 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 $\Gamma = 108\pm 22$ MeV/c$^2$, produced inclusively in $\Sigma^-$-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 d\sigma /dx_F = (5.2\pm 2.3) \mu b $ 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 $\Sigma^{*+}$ state. No corresponding peaks were observed in the $K^- p$ and $\Lambda \pi^{\pm}$ mass spectra.
03/2007;
-
Collaboration,
I Otterlund,
M I Adamovich,
M M Aggarwal,
N P Andreeva,
Z V Anson,
Z V Ameeva,
R Arora,
Y A Alexandrov,
S A Azimov, [......],
M I Tretyakova,
T P Trofimova,
H Q Wang,
Z O Weng,
R J Wilkes,
G F Xu,
D H Zhang,
P Y Zheng,
D C Zhou,
J C Zhou
[show abstract]
[hide abstract]
ABSTRACT: We report on recent results obtained by the EMUO1 collaboration from studies of 16O + emulsion, at 14.6, 60 and 200 A GeV, and 32S + emulsion and 32S + Au interactions at 200 A GeV. Shower-particle production in oxygen-induced interactions are studied over the energy range 2.1-200 A GeV. Scaling and limiting fragmentation are observed. Multiplicity and angular distributions of low energy target-associated particles are presented and compared with distributions obtained using the Ranft and the Fritiof simulation codes.
Physica Scripta 02/2007; 1990(T32):168. · 1.20 Impact Factor
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Collaboration (M. I. Adamovich,
M. M. Aggarwal,
Y. A. Alexandrov,
R. Amirikas,
N. P. Andreeva,
F. A. Avetyan,
S. K. Badyal,
A. M. Bakich,
E. S. Basova,
K. B. Bhalla, [......],
R. J. Wilkes,
T. Wu,
C. B. Yang,
Z. B. Yin,
L. Z. Yu,
Y. L. Yu,
D. H. Zhang,
P. Y. Zheng,
S. I. Zhokhova,
D. C. Zhou
[show abstract]
[hide abstract]
ABSTRACT: We analyse the multifractal structure of moments Gq in terms of a new variable X on data of 197Au, 32S and 16O induced interactions with emulsion nuclei and Monte Carlo generated samples. The dynamical properties of the produced particles are mapped onto multifractal spectra. We compare ln G in experimental data of 197Au, 32S and 16O with pure statistical fluctuations. It is shown that the stochasticity plays an important role for the G-moments.
EPL (Europhysics Letters) 01/2007; 44(5):571. · 2.17 Impact Factor
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Collaboration (M. I. Adamovich,
M. M. Aggarwal,
Y. A. Alexandrov,
R. Amirikas,
N. P. Andreeva,
F. A. Avetyan,
S. K. Badyal,
A. M. Bakich,
E. S. Basova,
K. B. Bhalla, [......],
R. J. Wilkes,
T. Wu,
C. B. Yang,
Z. B. Yin,
L. Z. Yu,
Y. L. Yu,
D. H. Zhang,
P. Y. Zheng,
S. I. Zhokhova,
D. C. Zhou
[show abstract]
[hide abstract]
ABSTRACT: We analyse the multifractal structure of moments Gq in terms of a new variable X on data of 197Au, 32S and 16O induced interactions with emulsion nuclei and Monte Carlo generated samples. The dynamical properties of the produced particles are mapped onto multifractal spectra. We compare ln G in experimental data of 197Au, 32S and 16O with pure statistical fluctuations. It is shown that the stochasticity plays an important role for the G-moments.
EPL (Europhysics Letters) 01/2007; 44(5):571. · 2.17 Impact Factor
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E S Ageev,
V Yu Alexakhin,
Yu A Alexandrov,
G D Alexeev,
A Amoroso,
B Badelek,
F Balestra,
J Ball,
G Baum,
Y Bedfer, [......],
U Wiedner,
M Wiesmann,
R Windmolders,
S Wirth,
W Wislicki,
A M Zanetti,
K Zaremba,
J Zhao,
R Ziegler,
A. Zvyagin
[show abstract]
[hide abstract]
ABSTRACT: We present a determination of the gluon polarization Delta G/G in the nucleon, based on the helicity asymmetry of quasi-real photoproduction events, Q^2<1(GeV/c)^2, with a pair of large transverse-momentum hadrons in the final state. The data were obtained by the COMPASS experiment at CERN using a 160 GeV polarized muon beam scattered on a polarized 6-LiD target. The helicity asymmetry for the selected events is <A_||/D> = 0.002 +- 0.019(stat.) +- 0.003(syst.). From this value, we obtain in a leading-order QCD analysis Delta G/G=0.024 +- 0.089(stat.) +- 0.057(syst.) at x_g = 0.095 and mu^2 =~ 3 (GeV}/c)^2.
Physics Letters B 02/2006; 633(1):25-32. · 3.95 Impact Factor
-
E S Ageev,
V Yu Alexakhin,
Yu A Alexandrov,
G D Alexeev,
A Amoroso,
B Badeek,
F Balestra,
J Ball,
G Baum,
Y Bedfer, [......],
Q. Weitzel,
M Wiesmann,
R Windmolders,
S Wirth,
W Wislicki,
A M Zanetti,
K Zaremba,
J Zhao,
R Ziegler,
A. Zvyagin
[show abstract]
[hide abstract]
ABSTRACT: Narrow Xi-pi+- and Xi-bar+pi+- resonances produced by quasi-real photons have been searched for by the COMPASS experiment at CERN. The study was stimulated by the recent observation of an exotic baryonic state decaying into Xi-pi-, at a mass of 1862 MeV, interpreted as a pentaquark. While the ordinary hyperon states Xi(1530)^0 and Xi-bar(1530)^0 are clearly seen, no exotic baryon is observed in the data taken in 2002 and 2003.
European Physical Journal C 05/2005; 41(4):469-474. · 3.63 Impact Factor
-
E S Ageev,
V Yu Alexakhin,
Yu A Alexandrov,
G D Alexeev,
A Amoroso,
B Badeek,
F Balestra,
J Ball,
G Baum,
Y Bedfer, [......],
Q. Weitzel,
M Wiesmann,
R Windmolders,
S Wirth,
W Wislicki,
A M Zanetti,
K Zaremba,
J Zhao,
R Ziegler,
A. Zvyagin
[show abstract]
[hide abstract]
ABSTRACT: We present a new measurement of the longitudinal spin asymmetry A_1^d and the spin-dependent structure function g_1^d of the deuteron in the range 1 GeV^2 < Q^2 < 100 GeV^2 and 0.004< x <0.7. The data were obtained by the COMPASS experiment at CERN using a 160 GeV polarised muon beam and a large polarised 6-LiD target. The results are in agreement with those from previous experiments and improve considerably the statistical accuracy in the region 0.004 < x < 0.03.
Physics Letters B 04/2005; 612(3-4):154-164. · 3.95 Impact Factor
-
V Yu Alexakhin,
Yu A Alexandrov,
G D Alexeev,
A Amoroso,
B Badeek,
F Balestra,
J Ball,
G Baum,
Y Bedfer,
P Berglund, [......],
E Weise,
M Wiesmann,
R Windmolders,
S Wirth,
W Wislicki,
A M Zanetti,
K Zaremba,
J Zhao,
R Ziegler,
A. Zvyagin
[show abstract]
[hide abstract]
ABSTRACT: First measurements of the Collins and Sivers asymmetries of charged hadrons produced in deep-inelastic scattering of muons on a transversely polarized 6-LiD target are presented. The data were taken in 2002 with the COMPASS spectrometer using the muon beam of the CERN SPS at 160 GeV/c. The Collins asymmetry turns out to be compatible with zero, as does the measured Sivers asymmetry within the present statistical errors.
Physical Review Letters 02/2005; 94(20). · 7.37 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: The dissociation of relativistic 7Li nuclei was studied with the photoemulsion technique. The nuclear photoemulsions have been exposed in the beam of 7Li at the momentum of 3 A GeV/c at the JINR synchrophasotron in Dubna. Along the scanned length 239.76 m of 7Li tracks, 1675 inelastic interactions have been found. For the first time the coherent dissociation of the relativistic 7Li nuclei into the (α + t) channel in the nuclear photoemulsion has been detected. The mean free path of this channel in emulsion is equal to 5.4 m and corresponds to the cross section which is equal to 23 ± 5 mb. Previously in the dissociation of the relativistic 6Li nuclei it was found that the main di-cluster configuration of the ground state of 6Li manifests itself as the main channel of coherent dissociation into α-particle and deuteron. The close values of relative yields and kinematic features of these two-particle dissociation channels of 7Li and 6Li suggest that a similar di-cluster configuration consisting of α-particle core and bound together outer nucleons predominates in the dissociating nuclei at relativistic energies also. The data presented prove the validity of the relativistic nuclei dissociation as an effective complementary method for the study of nuclear structure.
Journal of Physics G Nuclear and Particle Physics 09/2004; 30(10):1479. · 4.18 Impact Factor
-
M.I. Adamovich,
M.M. Aggarwal,
Y.A. Alexandrov,
R. Amirikas,
N.P. Andreeva,
S.K. Badyal,
A.M. Bakich,
E.S. Basova,
K.B. Bhalla,
A. Bhasin, [......],
Z.Q. Weng,
R.J. Wilkes,
C.B. Yang,
Z.B. Yin,
L.Z. Yu,
I.S. Zgura,
D.H. Zhang,
P.Y. Zheng,
S.I. Zhokhova,
D.C. Zhou
[show abstract]
[hide abstract]
ABSTRACT: The experimental data on the interactions of 10.6A GeV gold nuclei in nuclear emulsions are analyzed with particular emphasis
of target separation interactions and study of critical exponents. Charged fragment moments, conditional moments as well as
two and three – body asymmetries of the fast moving projectile particles are determined in terms of the total charge remaining
bound in the multiply charged projectile fragments. Some differences in the average yields of helium nuclei and heavier fragments
are observed, which may be attributed to a target effect. However, two and three-body asymmetries and conditional moments
indicate that the breakup mechanism of the projectile seems to be independent of target mass. We looked for evidence of critical
point observable in finite nuclei by study the resulting charged fragments distributions. We have obtained the values for
the critical exponents γ, β and τ and compare our results with those at lower energy experiment (1.0A GeV data). The values
suggest that a phase transition like behavior, is observed.
European Physical Journal A 07/1999; 5(4):429-440. · 2.19 Impact Factor
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Collaboration,
M I Adamovich,
M M Aggarwal,
Y A Alexandrov,
R Amirikas,
N P Andreeva,
Z V Anzon,
R Arora,
F A Avetyan,
S K Badyal, [......],
J Vrlakova,
H Q Wang,
Z Q Weng,
R J Wilkes,
Y L Xia,
C B Yang,
D H Zhang,
P Y Zheng,
S I Zhokhova,
D C Zhou
[show abstract]
[hide abstract]
ABSTRACT: An equation is presented, which allows us to calculate the dependence of the multiplicity of the particles produced in nucleus - nucleus collisions, , on an experimentally measured value , which is strongly correlated to the impact parameter b. The equation combines data from a wide range of projectile masses ( - 197) over a large momentum region . The possible meaning of the parameters is discussed in the context of a simple geometrical model.
Journal of Physics G Nuclear and Particle Physics 12/1998; 22(10):1469. · 4.18 Impact Factor
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M.I. Adamovich,
M.M. Aggarwal,
Y.A. Alexandrov,
R. Amirikas,
N.P. Andreeva,
Z.V. Anzon,
F.A. Avetyan,
S.K. Badyal,
A.M. Bakich,
E. Basova, [......],
X.R. Wang,
Z.Q. Weng,
R.J. Wilkes,
C.B. Yang,
Z.B. Yin,
L.Z. Yu,
D.H. Zhang,
P.Y. Zheng,
S.I. Zhokhova,
D.C. Zhou
[show abstract]
[hide abstract]
ABSTRACT: Using emulsion detectors a transverse-momentum analysis of projectile fragments has been performed in Au induced nuclear interactions at 11.6 A GeV/c. Evidence for collective flow of the projectile fragments has been obtained. Angular distributions of the principal vectors of projectile and target fragments have shown strong azimuthal correlation.
European Physical Journal A 04/1998; 2(1):61-67. · 2.19 Impact Factor
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M.I. Adamovich,
M.M. Aggarwal,
Y.A. Alexandrov,
R. Amirikas,
N.P. Andreeva,
Z.V. Anzon,
F.A. Avetyan,
S.K. Badyal,
A.M. Bakich,
E. Baklitskaya, [......],
X.R. Wang,
Z.Q. Weng,
R.J. Wilkes,
C.B. Yang,
Z.B. Yin,
L.Z. Yu,
D.H. Zhang,
P.Y. Zheng,
S.I. Zhokhova,
D.C. Zhou
[show abstract]
[hide abstract]
ABSTRACT: Recent results from the EMU-01/12 collaboration are presented for 10.7 GeV/nucleon gold nuclei interactions in emulsion. The distributions of "bound" charge (Zbound,Zb3), multiplicity distributions, fragment correlations and fluctuations are discussed. The data are compared to similar results obtained on the ALADIN setup at 600 MeV/nucleon. It is shown that multifragmentation of gold nuclei at high and intermediate energies has common features. It is also obtained that the IMFs have reduced multiplicity at high energies. The data are analyzed within the scope of the statistical model of multifragmentation. This model requires the following predetermined model ingredients: mass, charge and excitation energy of nuclear residuals. The simple estimation method of these characteristics is proposed in the framework of the Glauber approach. It is shown that the multifragmentation model reproduces qualitatively the present data. A dramatic discrepancy between the predicted and experimental yield of two charged fragments is found. The evolution of transverse momentum of fragments as a function of Zbound is presented. It is shown that the model greatly underpredicts the transverse momentum of fragments. It is interpreted as evidence of a strong radial flow of spectator fragments.
Zeitschrift für Physik A Hadrons and Nuclei 10/1997; 359(3):277-290.
-
M.I. Adamovich,
M.M. Aggarwal,
Y.A. Alexandrov,
R. Amirikas,
N.P. Andreeva,
Z.V. Anzon,
R. Arora,
F.A. Avetyan,
S.K. Badyal,
A.M. Bakich, [......],
J. Vrlakova,
H.Q. Wang,
Z.Q. Weng,
R.J. Wilkes,
Y.L. Xia,
C.B. Yang,
D.H. Zhang,
P.Y. Zheng,
S.I. Zhokhova,
D.C. Zhou
[show abstract]
[hide abstract]
ABSTRACT: Complex analysis of Gold interaction with photoemulsion nuclei at 10.7 GeV/nucleon has been performed. The data obtained were compared with a modified FRITIOF model which allowance is made for exitation of nuclear residuals (after interaction). A comparison was also made with cascade-evaporation model. Experimental data contradict the CEM supposition of fast resonance decay and complete cascading. The modified FRITIOF model fairly well reproduces experimental observations. According to the model the production mechanism of charged particles must remain unchangable in the 4-200 GeV/n energy range.
Zeitschrift für Physik A Hadrons and Nuclei 07/1997; 358(3):337-351.
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M. I. Adamovich,
E. Albertson,
Yu. A. Alexandrov,
D. Barberis,
C. Bérat,
W. Beusch,
K. H. Brenzinger,
S. Brons,
W. Bruckner,
A. Brunengo, [......],
L. Schmitt,
H. -W. Siebert,
A. Simon,
A. Trombini,
R. Touillon,
B. Volkemer,
Th. Walcher,
G. Wälder,
A. Wenzel,
M. V. Zavertyaev
[show abstract]
[hide abstract]
ABSTRACT: The polarization of
L 0 ,[`(L)] 0 , S+\Lambda ^0 , \overline \Lambda ^0 , \Sigma ^ +
and[`(L)] 0 \overline \Lambda ^0
is observed, as was also the case in proton beam data. At transverse momenta of about 1 GeV/c and + show little polarization, significantly lower than in the proton beam data, while
– have a polarization comparable to the polarization of 0 produced in proton beams.
Zeitschrift für Physik A Hadrons and Nuclei 11/1995; 350(4):379-386.
-
M. J. Adamovich,
M. M. Aggarwal,
Y. A. Alexandrov,
R. Amirikas,
N. P. Andreeva,
Z. V. Anzon,
R. Arora,
F. A. Avetyan,
S. K. Badyal,
A. M. Bakich, [......],
J. Vrlakova,
H. Q. Wang,
Z. Q. Weng,
R. J. Wilkes,
Y. L. Xia,
C. B. Yang,
D. H. Zhang,
P. Y. Zheng,
S. I. Zhokhova,
D. C. Zhou
[show abstract]
[hide abstract]
ABSTRACT: The mechanism for producing slow, target associated particles in high energy heavy ion collisions is investigated. It is shown that the same mechanism which was proposed for hadron induced interactions is likely to appear also for heavy-ion reactions. The results indicate however a much weaker correlation between impact parameter and yield of slow particles.
Zeitschrift für Physik C 08/1995; 65(3):421-429.
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M. I. Adamovich,
E. Albertson,
Yu. A. Alexandrov,
D. Barberis,
M. Beck,
C. Berat,
W. Beusch,
M. Boss,
S. Brons,
W. Bruckner, [......],
O. Thilmann,
A. Trombini,
E. Vesin,
B. Volkemer,
K. Vorwalter,
Th. Walcher,
G. Walder,
R. Werding,
E. Wittmann,
M. V. Zavertyaev
[show abstract]
[hide abstract]
ABSTRACT: We present the measurement of the lifetime of the Omega_c we have
performed using three independent data samples from two different decay
modes. Using a Sigma- beam of 340 GeV/c we have obtained clean signals
for the Omega_c decaying into Xi- K- pi+ pi+ and Omega- pi+ pi- pi+,
avoiding topological cuts normally used in charm analysis. The short but
measurable lifetime of the Omega_c is demonstrated by a clear
enhancement of the signals at short but finite decay lengths. Using a
continuous maximum likelihood method we determined the lifetime to be
tau(Omega_c) = 55 +13-11(stat) +18-23(syst) fs. This makes the Omega_c
the shortest living weakly decaying particle observed so far. The short
value of the lifetime confirms the predicted pattern of the charmed
baryon lifetimes and demonstrates that the strong interaction plays a
vital role in the lifetimes of charmed hadrons.
Physics Letters B 08/1995; 358:151-161. · 3.95 Impact Factor
