248 research outputs found
ΠΠΎΠΊΡΠ°ΡΠ΅Π½ΠΈΠΉ ΡΠΈΠ½ΡΠ΅Π·, ΡΠΏΠ΅ΠΊΡΡΠ°Π»ΡΠ½Ρ Ρ Π°ΡΠ°ΠΊΡΠ΅ΡΠΈΡΡΠΈΠΊΠΈ ΡΠ° ΠΏΡΠΎΡΡΠΎΡΠΎΠ²Π° Π±ΡΠ΄ΠΎΠ²Π° Π΅ΡΠΈΠ»ΠΎΠ²ΠΎΠ³ΠΎ Π΅ΡΡΠ΅ΡΡ 2-Π³ΡΠ΄ΡΠΎΠΊΡΠΈ-8-ΠΌΠ΅ΡΠΈΠ»-4-ΠΎΠΊΡΠΎ-4Π-ΠΏΡΡΠΈΠ΄ΠΎ[1,2-Π°]ΠΏΡΡΠΈΠΌΡΠ΄ΠΈΠ½-3-ΠΊΠ°ΡΠ±ΠΎΠ½ΠΎΠ²ΠΎΡ ΠΊΠΈΡΠ»ΠΎΡΠΈ
The improved method for obtaining ethyl 2-hydroxy-8-methyl-4-oxo-4H-pyrido[1,2-a]pyrimidine-3-carboxylate being of interest as a base for synthesis of antiviral medicines has been suggested. The method involves a gradual addition of the solution of 2-amino-4-methylpyridine in triethylmethanetricarboxylate used as an acylating and condensing agent, as well as a high boiling heating agent simultaneously in the excess of triethylmethanetricarboxylate preheated to 150Β°C. This modification allows not only to reduce considerably regeneration of triethylmethanetricarboxylate taken in excess, but practically to avoid completely the undesirable formation of by-product β 2-hydroxy-8-methyl-N-(4-methypyridin-2-yl)-4-oxo-4H-pyrido[1,2-a]pyrimidine-3-carboxamide. It has been found by X-ray diffraction analysis that in the crystal the ethyl 2-hydroxy-8-methyl-4-oxo-4H-pyrido[1,2-a]pyrimidine-3-carboxylate synthesized exists in the zwitterionic form with localization of the positive charge at the protonated nitrogen atom and the negative charge at the carbon atom in position 3 of the pyridopyrimidine ring. Based on the study of NMR 1H and 13C spectra the assumption that the test compound exits as an equilibrium mixture of two tautomeric forms in solution has been expressed.ΠΡΠ΅Π΄Π»ΠΎΠΆΠ΅Π½ ΡΠ»ΡΡΡΠ΅Π½Π½ΡΠΉ ΡΠΏΠΎΡΠΎΠ± ΠΏΠΎΠ»ΡΡΠ΅Π½ΠΈΡ ΡΡΠΈΠ»ΠΎΠ²ΠΎΠ³ΠΎ ΡΡΠΈΡΠ° 2-Π³ΠΈΠ΄ΡΠΎΠΊΡΠΈ-8-ΠΌΠ΅ΡΠΈΠ»-4-ΠΎΠΊΡΠΎ-4Π-ΠΏΠΈΡΠΈΠ΄ΠΎ[1,2-Π°] ΠΏΠΈΡΠΈΠΌΠΈΠ΄ΠΈΠ½-3-ΠΊΠ°ΡΠ±ΠΎΠ½ΠΎΠ²ΠΎΠΉ ΠΊΠΈΡΠ»ΠΎΡΡ, ΠΏΡΠ΅Π΄ΡΡΠ°Π²Π»ΡΡΡΠ΅Π³ΠΎ ΠΈΠ½ΡΠ΅ΡΠ΅Ρ ΠΊΠ°ΠΊ ΠΎΡΠ½ΠΎΠ²Π° Π΄Π»Ρ ΡΠΈΠ½ΡΠ΅Π·Π° ΠΏΡΠΎΡΠΈΠ²ΠΎΠ²ΠΈΡΡΡΠ½ΡΡ
Π»Π΅ΠΊΠ°ΡΡΡΠ²Π΅Π½Π½ΡΡ
ΡΡΠ΅Π΄ΡΡΠ². ΠΠ΅ΡΠΎΠ΄ Π·Π°ΠΊΠ»ΡΡΠ°Π΅ΡΡΡ Π² ΠΏΠΎΡΡΠ΅ΠΏΠ΅Π½Π½ΠΎΠΌ ΠΏΡΠΈΠ±Π°Π²Π»Π΅Π½ΠΈΠΈ Π² ΠΏΡΠ΅Π΄Π²Π°ΡΠΈΡΠ΅Π»ΡΠ½ΠΎ Π½Π°Π³ΡΠ΅ΡΡΠΉ Π΄ΠΎ 150Β°Π‘ ΠΈΠ·Π±ΡΡΠΎΠΊ ΡΡΠΈΡΡΠΈΠ»-ΠΌΠ΅ΡΠ°Π½ΡΡΠΈΠΊΠ°ΡΠ±ΠΎΠΊΡΠΈΠ»Π°ΡΠ° ΡΠ°ΡΡΠ²ΠΎΡΠ° 2-Π°ΠΌΠΈΠ½ΠΎ-4-ΠΌΠ΅ΡΠΈΠ»ΠΏΠΈΡΠΈΠ΄ΠΈΠ½Π° Π² ΡΡΠΈΡΡΠΈΠ»-ΠΌΠ΅ΡΠ°Π½ΡΡΠΈ-ΠΊΠ°ΡΠ±ΠΎΠΊΡΠΈΠ»Π°ΡΠ΅, ΠΈΡΠΏΠΎΠ»ΡΠ·ΡΠ΅ΠΌΠΎΠΌ Π² ΠΊΠ°ΡΠ΅ΡΡΠ²Π΅ Π°ΡΠΈΠ»ΠΈΡΡΡΡΠ΅Π³ΠΎ ΠΈ ΠΊΠΎΠ½Π΄Π΅Π½ΡΠΈΡΡΡΡΠ΅Π³ΠΎ Π°Π³Π΅Π½ΡΠ°, Π° ΡΠ°ΠΊΠΆΠ΅ Π²ΡΡΠΎΠΊΠΎΠΊΠΈΠΏΡΡΠ΅Π³ΠΎ ΡΠ΅ΠΏΠ»ΠΎΠ½ΠΎΡΠΈΡΠ΅Π»Ρ ΠΎΠ΄Π½ΠΎΠ²ΡΠ΅ΠΌΠ΅Π½Π½ΠΎ. Π’Π°ΠΊΠ°Ρ ΠΌΠΎΠ΄ΠΈΡΠΈΠΊΠ°ΡΠΈΡ ΠΏΠΎΠ·Π²ΠΎΠ»ΡΠ΅Ρ Π½Π΅ ΡΠΎΠ»ΡΠΊΠΎ Π·Π½Π°ΡΠΈΡΠ΅Π»ΡΠ½ΠΎ ΡΠΏΡΠΎΡΡΠΈΡΡ ΡΠ΅Π³Π΅Π½Π΅ΡΠ°ΡΠΈΡ Π²Π·ΡΡΠΎΠ³ΠΎ Π² ΠΈΠ·Π±ΡΡΠΊΠ΅ ΡΡΠΈΡΡΠΈΠ»ΠΌΠ΅ΡΠ°Π½ΡΡΠΈ-ΠΊΠ°ΡΠ±ΠΎΠΊΡΠΈΠ»Π°ΡΠ°, Π½ΠΎ ΠΈ ΠΏΡΠ°ΠΊΡΠΈΡΠ΅ΡΠΊΠΈ ΠΏΠΎΠ»Π½ΠΎΡΡΡΡ ΠΈΠ·Π±Π΅ΠΆΠ°ΡΡ Π½Π΅ΠΆΠ΅Π»Π°ΡΠ΅Π»ΡΠ½ΠΎΠ³ΠΎ ΠΎΠ±ΡΠ°Π·ΠΎΠ²Π°Π½ΠΈΡ ΠΏΠΎΠ±ΠΎΡΠ½ΠΎΠ³ΠΎ 2-Π³ΠΈΠ΄ΡΠΎΠΊΡΠΈ-8-ΠΌΠ΅ΡΠΈΠ»-4-ΠΎΠΊΡΠΎ-N-(4-ΠΌΠ΅ΡΠΈΠ»ΠΏΠΈΡΠΈΠ΄ΠΈΠ½-2-ΠΈΠ»)-4Π-ΠΏΠΈΡΠΈΠ΄ΠΎ[1,2-Π°]ΠΏΠΈΡΠΈΠΌΠΈΠ΄ΠΈΠ½-3-ΠΊΠ°ΡΠ±ΠΎΠΊΡΠ°ΠΌΠΈΠ΄Π°. Π‘ ΠΏΠΎΠΌΠΎΡΡΡ ΡΠ΅Π½ΡΠ³Π΅Π½ΠΎΡΡΡΡΠΊΡΡΡΠ½ΠΎΠ³ΠΎ Π°Π½Π°Π»ΠΈΠ·Π° ΡΡΡΠ°Π½ΠΎΠ²Π»Π΅Π½ΠΎ, ΡΡΠΎ Π² ΠΊΡΠΈΡΡΠ°Π»Π»Π΅ ΡΠΈΠ½ΡΠ΅Π·ΠΈΡΠΎΠ²Π°Π½Π½ΡΠΉ ΡΡΠΈΠ»ΠΎΠ²ΡΠΉ ΡΡΠΈΡ 2-Π³ΠΈΠ΄ΡΠΎΠΊΡΠΈ-8-ΠΌΠ΅ΡΠΈΠ»-4-ΠΎΠΊΡΠΎ-4Π-ΠΏΠΈΡΠΈΠ΄ΠΎ[1,2-Π°]ΠΏΠΈΡΠΈΠΌΠΈΠ΄ΠΈΠ½-3-ΠΊΠ°ΡΠ±ΠΎΠ½ΠΎΠ²ΠΎΠΉ ΠΊΠΈΡΠ»ΠΎΡΡ ΡΡΡΠ΅ΡΡΠ²ΡΠ΅Ρ Π² ΡΠ²ΠΈΡΡΠ΅Ρ-ΠΈΠΎΠ½Π½ΠΎΠΉ ΡΠΎΡΠΌΠ΅ Ρ Π»ΠΎΠΊΠ°Π»ΠΈΠ·Π°ΡΠΈΠ΅ΠΉ ΠΏΠΎΠ»ΠΎΠΆΠΈΡΠ΅Π»ΡΠ½ΠΎΠ³ΠΎ Π·Π°ΡΡΠ΄Π° Π½Π° ΠΏΡΠΎΡΠΎΠ½ΠΈΡΠΎΠ²Π°Π½Π½ΠΎΠΌ Π°ΡΠΎΠΌΠ΅ Π°Π·ΠΎΡΠ° ΠΈ ΠΎΡΡΠΈΡΠ°ΡΠ΅Π»ΡΠ½ΠΎΠ³ΠΎ Π·Π°ΡΡΠ΄Π° Π½Π° Π°ΡΠΎΠΌΠ΅ ΡΠ³Π»Π΅ΡΠΎΠ΄Π° Π² ΠΏΠΎΠ»ΠΎΠΆΠ΅Π½ΠΈΠΈ 3 ΠΏΠΈΡΠΈΠ΄ΠΎΠΏΠΈΡΠΈΠΌΠΈΠ΄ΠΈΠ½ΠΎΠ²ΠΎΠ³ΠΎ ΡΠ΄ΡΠ°. ΠΠ° ΠΎΡΠ½ΠΎΠ²Π°Π½ΠΈΠΈ ΠΈΠ·ΡΡΠ΅Π½ΠΈΡ ΡΠΏΠ΅ΠΊΡΡΠΎΠ² Π―ΠΠ 1Π ΠΈ 13Π‘ Π²ΡΡΠΊΠ°Π·Π°Π½ΠΎ ΠΏΡΠ΅Π΄ΠΏΠΎΠ»ΠΎΠΆΠ΅Π½ΠΈΠ΅, ΡΡΠΎ ΠΈΡΡΠ»Π΅Π΄ΡΠ΅ΠΌΠΎΠ΅ ΡΠΎΠ΅Π΄ΠΈΠ½Π΅Π½ΠΈΠ΅ ΠΈ Π² ΡΠ°ΡΡΠ²ΠΎΡΠ΅ ΡΡΡΠ΅ΡΡΠ²ΡΠ΅Ρ Π² Π²ΠΈΠ΄Π΅ ΡΠ°Π²Π½ΠΎΠ²Π΅ΡΠ½ΠΎΠΉ ΡΠΌΠ΅ΡΠΈ Π΄Π²ΡΡ
ΡΠ°ΡΡΠΎΠΌΠ΅ΡΠ½ΡΡ
ΡΠΎΡΠΌ.ΠΠ°ΠΏΡΠΎΠΏΠΎΠ½ΠΎΠ²Π°Π½ΠΎ ΠΏΠΎΠΊΡΠ°ΡΠ΅Π½ΠΈΠΉ ΡΠΏΠΎΡΡΠ± ΠΎΠ΄Π΅ΡΠΆΠ°Π½Π½Ρ Π΅ΡΠΈΠ»ΠΎΠ²ΠΎΠ³ΠΎ Π΅ΡΡΠ΅ΡΡ 2-Π³ΡΠ΄ΡΠΎΠΊΡΠΈ-8-ΠΌΠ΅ΡΠΈΠ»-4-ΠΎΠΊΡΠΎ-4Π-ΠΏΡΡΠΈΠ΄ΠΎ [1,2-Π°]ΠΏΡΡΠΈΠΌΡΠ΄ΠΈΠ½-3-ΠΊΠ°ΡΠ±ΠΎΠ½ΠΎΠ²ΠΎΡ ΠΊΠΈΡΠ»ΠΎΡΠΈ, ΡΠΊΠΈΠΉ ΠΏΡΠ΅Π΄ΡΡΠ°Π²Π»ΡΡ ΡΠ½ΡΠ΅ΡΠ΅Ρ ΡΠΊ ΠΎΡΠ½ΠΎΠ²Π° Π΄Π»Ρ ΡΠΈΠ½ΡΠ΅Π·Ρ ΠΏΡΠΎΡΠΈΠ²ΡΡΡΡΠ½ΠΈΡ
Π»ΡΠΊΠ°ΡΡΡΠΊΠΈΡ
Π·Π°ΡΠΎΠ±ΡΠ². ΠΠ΅ΡΠΎΠ΄ ΠΏΠΎΠ»ΡΠ³Π°Ρ Ρ ΠΏΠΎΡΡΡΠΏΠΎΠ²ΠΎΠΌΡ Π΄ΠΎΠ΄Π°Π²Π°Π½Π½Ρ Π² ΠΏΠΎΠΏΠ΅ΡΠ΅Π΄Π½ΡΠΎ Π½Π°Π³ΡΡΡΠΈΠΉ Π΄ΠΎ 150Β°Π‘ Π½Π°Π΄Π»ΠΈΡΠΎΠΊ ΡΡΠΈΠ΅ΡΠΈΠ»ΠΌΠ΅ΡΠ°Π½ΡΡΠΈΠΊΠ°ΡΠ±ΠΎΠΊΡΠΈΠ»Π°ΡΡ ΡΠΎΠ·ΡΠΈΠ½Ρ 2-Π°ΠΌΡΠ½ΠΎ-4-ΠΌΠ΅ΡΠΈΠ»ΠΏΡΡΠΈΠ΄ΠΈΠ½Ρ Π² ΡΡΠΈΠ΅ΡΠΈΠ»ΠΌΠ΅ΡΠ°Π½ΡΡΠΈΠΊΠ°ΡΠ±ΠΎΠΊΡΠΈΠ»Π°ΡΡ, ΡΠΎ Π²ΠΈΠΊΠΎΡΠΈΡΡΠΎΠ²ΡΡΡΡΡΡ ΡΠΊ Π°ΡΠΈΠ»ΡΡΡΠΈΠΉ ΡΠ° ΠΊΠΎΠ½Π΄Π΅Π½ΡΡΡΡΠΈΠΉ Π°Π³Π΅Π½Ρ, Π° ΡΠ°ΠΊΠΎΠΆ ΡΠΊ Π²ΠΈΡΠΎΠΊΠΎΠΊΠΈΠΏΠ»ΡΡΠΈΠΉ ΡΠ΅ΠΏΠ»ΠΎΠ½ΠΎΡΡΠΉ ΠΎΠ΄Π½ΠΎΡΠ°ΡΠ½ΠΎ. Π’Π°ΠΊΠ° ΠΌΠΎΠ΄ΠΈΡΡΠΊΠ°ΡΡΡ Π΄ΠΎΠ·Π²ΠΎΠ»ΡΡ Π½Π΅ ΡΡΠ»ΡΠΊΠΈ Π·Π½Π°ΡΠ½ΠΎ ΡΠΏΡΠΎΡΡΠΈΡΠΈ ΡΠ΅Π³Π΅Π½Π΅ΡΠ°ΡΡΡ Π²Π·ΡΡΠΎΠ³ΠΎ Ρ Π½Π°Π΄Π»ΠΈΡΠΊΡ ΡΡΠΈΠ΅ΡΠΈΠ»ΠΌΠ΅ΡΠ°Π½ΡΡΠΈΠΊΠ°ΡΠ±ΠΎΠΊΡΠΈΠ»Π°ΡΡ, Π°Π»Π΅ ΠΉ ΠΏΡΠ°ΠΊΡΠΈΡΠ½ΠΎ ΠΏΠΎΠ²Π½ΡΡΡΡ ΡΠ½ΠΈΠΊΠ½ΡΡΠΈ Π½Π΅Π±Π°ΠΆΠ°Π½ΠΎΠ³ΠΎ ΡΡΠ²ΠΎΡΠ΅Π½Π½Ρ ΠΏΠΎΠ±ΡΡΠ½ΠΎΠ³ΠΎ 2-Π³ΡΠ΄ΡΠΎΠΊΡΠΈ-8-ΠΌΠ΅ΡΠΈΠ»-4-ΠΎΠΊΡΠΎ-N-(4-ΠΌΠ΅ΡΠΈΠ»ΠΏΡΡΠΈΠ΄ΠΈΠ½-2-ΡΠ»)-4Π-ΠΏΡΡΠΈΠ΄ΠΎ[1,2-Π°]ΠΏΡΡΠΈΠΌΡΠ΄ΠΈΠ½-3-ΠΊΠ°ΡΠ±ΠΎΠΊΡΠ°ΠΌΡΠ΄Ρ. ΠΠ° Π΄ΠΎΠΏΠΎΠΌΠΎΠ³ΠΎΡ ΡΠ΅Π½ΡΠ³Π΅Π½ΠΎΡΡΡΡΠΊΡΡΡΠ½ΠΎΠ³ΠΎ Π°Π½Π°Π»ΡΠ·Ρ Π²ΡΡΠ°Π½ΠΎΠ²Π»Π΅Π½ΠΎ, ΡΠΎ Π² ΠΊΡΠΈΡΡΠ°Π»Ρ ΡΠΈΠ½ΡΠ΅Π·ΠΎΠ²Π°Π½ΠΈΠΉ Π΅ΡΠΈΠ»ΠΎΠ²ΠΈΠΉ Π΅ΡΡΠ΅Ρ 2-Π³ΡΠ΄ΡΠΎΠΊΡΠΈ-8-ΠΌΠ΅ΡΠΈΠ»-4-ΠΎΠΊΡΠΎ-4Π-ΠΏΡΡΠΈΠ΄ΠΎ[1,2-Π°]ΠΏΡΡΠΈΠΌΡΠ΄ΠΈΠ½-3-ΠΊΠ°ΡΠ±ΠΎΠ½ΠΎΠ²ΠΎΡ ΠΊΠΈΡΠ»ΠΎΡΠΈ ΡΡΠ½ΡΡ Ρ ΡΠ²ΡΡΡΠ΅Ρ-ΡΠΎΠ½Π½ΡΠΉ ΡΠΎΡΠΌΡ Π· Π»ΠΎΠΊΠ°Π»ΡΠ·Π°ΡΡΡΡ ΠΏΠΎΠ·ΠΈΡΠΈΠ²Π½ΠΎΠ³ΠΎ Π·Π°ΡΡΠ΄Ρ Π½Π° ΠΏΡΠΎΡΠΎΠ½ΠΎΠ²Π°Π½ΠΎΠΌΡ Π°ΡΠΎΠΌΡ Π½ΡΡΡΠΎΠ³Π΅Π½Ρ Ρ Π½Π΅Π³Π°ΡΠΈΠ²Π½ΠΎΠ³ΠΎ Π·Π°ΡΡΠ΄Ρ Π½Π° Π°ΡΠΎΠΌΡ ΠΊΠ°ΡΠ±ΠΎΠ½Ρ Ρ ΠΏΠΎΠ»ΠΎΠΆΠ΅Π½Π½Ρ 3 ΠΏΡΡΠΈΠ΄ΠΎΠΏΡΡΠΈΠΌΡΠ΄ΠΈΠ½ΠΎΠ²ΠΎΠ³ΠΎ ΡΠ΄ΡΠ°. ΠΠ° ΠΎΡΠ½ΠΎΠ²Ρ Π²ΠΈΠ²ΡΠ΅Π½Π½Ρ ΡΠΏΠ΅ΠΊΡΡΡΠ² Π―ΠΠ 1Π ΡΠ° 13Π‘ Π·ΡΠΎΠ±Π»Π΅Π½ΠΎ ΠΏΡΠΈΠΏΡΡΠ΅Π½Π½Ρ, ΡΠΎ Π΄ΠΎΡΠ»ΡΠ΄ΠΆΡΠ²Π°Π½Π° ΡΠΏΠΎΠ»ΡΠΊΠ° Ρ Π² ΡΠΎΠ·ΡΠΈΠ½Ρ ΡΡΠ½ΡΡ Ρ Π²ΠΈΠ³Π»ΡΠ΄Ρ ΡΡΠ²Π½ΠΎΠ²Π°ΠΆΠ½ΠΎΡ ΡΡΠΌΡΡΡ Π΄Π²ΠΎΡ
ΡΠ°ΡΡΠΎΠΌΠ΅ΡΠ½ΠΈΡ
ΡΠΎΡΠΌ
Observation of a narrow baryon resonance with positive strangeness formed in Xe collisions
The charge-exchange reaction K^+ Xe --> K^0 p Xe' is investigated using the
data of the DIANA experiment. The distribution of the pK^0 effective mass shows
a prominent enhancement near 1538 MeV formed by \sim 80 events above the
background, whose width is consistent with being entirely due to the
experimental resolution. Under the selections based on a simulation of K^+Xe
collisions, the statistical significance of the signal reaches 5.5\sigma. We
interpret this observation as strong evidence for formation of a pentaquark
baryon with positive strangeness, \Theta^+(uudd\bar{s}), in the charge-exchange
reaction K^+ n --> K^0 p on a bound neutron. The mass of the \Theta^+ baryon is
measured as m(\Theta^+) = 1538+-2 MeV. Using the ratio between the numbers of
resonant and non-resonant charge-exchange events in the peak region, the
intrinsic width of this baryon resonance is determined as \Gamma(\Theta^+) =
0.34+-0.10 MeV.Comment: 19 pages, 8 figure
Observation of a baryon resonance with positive strangeness in K+ collisions with Xe nuclei
The status of our investigation of low-energy Xe collisions in the Xenon
bubble chamber DIANA is reported. In the charge-exchange reaction the spectrum of effective mass shows a resonant enhancement
with MeV/c and ^24.4\sigma$. The mass and width of the
observed resonance are consistent with expectations for the lightest member of
the anti-decuplet of exotic pentaquark baryons, as predicted in the framework
of the chiral soliton model.Comment: 9 pages, 4 figure
Single spin asymmetry measurements for inclusive productions in and \pi^-+\p_{\uparrow}\to \pi^0+X reactions at 70 and 40 GeV respectively
The inclusive asymmetries were measured in reactions and at 70 and 40 GeV/c respectively. The
measurements were made at the central region (for the first reaction) and
asymmetry is compatible with zero in the entire measured region. For the
second reaction the asymmetry is zero for small region () and increases with growth of . Averaged
over the interval the asymmetry was .Comment: 4 pages, 2 figures; Presented at SPIN-2004 at Trieste, October
10-16,200
Further evidence for formation of a narrow baryon resonance with positive strangeness in K+ collisions with Xe nuclei
We have continued our investigation of the charge-exchange reaction K^+ Xe
--> K^0 p Xe' in the bubble chamber DIANA. In agreement with our previous
results based on part of the present statistics, formation of a narrow p K^0
resonance with mass of 1537+-2 MeV/c^2 is observed in the elementary transition
K^+ n --> K^0 p on a neutron bound in the Xenon nucleus. Visible width of the
peak is consistent with being entirely due to instrumental resolution and
allows to place an upper limit on its intrinsic width: \Gamma < 9 MeV/c^2. A
more precise estimate of the resonance intrinsic width, \Gamma = 0.36+-0.11
MeV/c^2, is obtained from the ratio between the numbers of resonant and
non-resonant charge-exchange events. The signal is observed in a restricted
interval of incident K^+ momentum, that is consistent with smearing of a narrow
p K^0 resonance by Fermi motion of the target neutron. Statistical significance
of the signal is some 7.3, 5.3, and 4.3 standard deviations for the estimators
S/sqrt{B}, S/sqrt{S+B}, and S/sqrt{S+2B}, respectively. This observation
confirms and reinforces our earlier results, and offers strong evidence for
formation of a pentaquark baryon with positive strangeness in the
charge-exchange reaction K^+ n --> K^0 p on a bound neutron.Comment: 13 pages, 8 figures, some chenges in text and references, more
precise estimate of Theta(1540) to add, submitted to Phys.Atom.Nucl(Yad.Fiz.
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