We have analyzed data of the DISTO experiment on the exclusive
pp
→
K
+
Λ
p
process at
T
p
= 2.85 GeV to search for a
K
−
pp
( ≡
X
) nuclear bound state to be formed in the
pp
→
K
+
+
X
...reaction. The deviation spectra of the
K
+
missing-mass Δ
M
(
K
+
) and Λ
p
invariant-mass
M
(Λ
p
) with selection of large-angle proton emission revealed a structure with
M
X
= 2265 ±2 MeV/
c
2
and
Γ
X
= 118 ±8 MeV.
The DISTO first level trigger at SATURNE Balestra, F.; Bedfer, Y.; Bertini, R. ...
IEEE transactions on nuclear science,
06/1998, Letnik:
45, Številka:
3
Journal Article
Recenzirano
The DISTO collaboration has built a large-acceptance magnetic spectrometer designed to provide broad kinematic coverage of multi-particle final states produced in pp scattering. The spectrometer has ...been installed in the polarized proton beam of the Saturne accelerator in Saclay to study polarization observables in the p/spl I.oarr/p/spl rarr/pK/sup +/Y/spl I.oarr/ (Y=/spl Lambda/, /spl Sigma//sup 0/ or Y*) reaction and vector meson production (/spl phi/, /spl omega/, and /spl rho/) in pp collisions. The common signature of such events is the multiplicity of four charged particles in the final state. A flexible 1st level trigger which uses topological information from fast detectors (scintillating fibers and hodoscope) has been built. It is completely software programmable through a menu-driven user interface and allows switching between production and monitor triggers on successive beam spills.
The DISTO collaboration has built a large-acceptance magnetic spectrometer designed to provide broad kinematic coverage of multiparticle final states produced in pp scattering. The spectrometer has ...been installed in the polarized proton beam of the Saturne accelerator in Saclay to study polarization observables in the p/spl I.oarr/p/spl rarr/pK/sup +/Y/spl I.oarr/ (Y=/spl Lambda/,/spl Sigma//sup 0/ or Y*) reaction and vector meson production (/spl phi/,/spl omega/ and /spl rho/) in pp collisions. The data acquisition system is based on a VME 68030 CPU running the OS/9 operating system, housed in a single VME crate together with the CAMAC interface, the triple port ECL memories, and four RISC R3000 CPU. The digitization of signals from the detectors is made by PCOS III and FERA front-end electronics. Data of several events belonging to a single Saturne extraction are stored in VME triple-port ECL memories using a hardwired fast sequencer. The buffer, optionally filtered by the RISC R3000 CPU, is recorded on a DLT cassette by DAQ CPU using the on-board SCSI interface during the acceleration cycle. Two UNIX workstations are connected to the VME CPUs through a fast parallel bus and the Local Area Network. They analyze a subset of events for on-line monitoring. The data acquisition system is able to read and record 3500 eV/burst in the present configuration with a dead time of 15%.
We have analyzed data of the DISTO experiment on the exclusive pp --> pLambdaK+ reaction at 2.85 GeV to search for a strongly bound compact K- pp(approximately = X) state to be formed in the pp --> ...K+ + X reaction. The observed spectra of the K+ missing mass and the pLambda invariant-mass with high transverse momenta of p and K+ revealed a broad distinct peak of 26-sigma confidence with a mass M(X)=2267+/-3(stat)+/-5(syst) MeV/c2 and a width Gamma(X)=118+/-8(stat)+/-10(syst) MeV. The enormously large cross section indicates formation of a compact K- pp with a large binding energy of B(K)=103 MeV, which can be a possible gateway toward cold and dense kaonic nuclear matter.
We present the latest results from the DISTO collaboration on vector meson production (
pp → ppV
) with a polarised proton beam of 3.67 GeV/c: the total and the differential cross sections for ω, θ ...and ϱ
0 production; the preliminary analysing power
A
y
for θ production.
Total and differential cross sections for the exclusive reaction pp-->pp rho observed via the pi(+)pi(-) decay channel have been measured at p(beam)=3.67 GeV/c. The observed total meson production ...cross section is determined to be (23.4+/-0.8+/-8) mu b and is significantly lower than typical cross sections used in model calculations for heavy-ion collisions. The differential cross sections measured indicate a strong anisotropy (approximately cos(theta(CM)(rho)) in the rho(0) meson production.
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