45 research outputs found
The front-end electronics for the COMPASS MWPCs
In the COMPASS experiment 34 planes of MWPCs for about 26,000 readout channels of MWPCs are used. The very high rate of the muon and hadron beams, and the consequently high trigger rate, requires the use of a front-end electronics with new conceptual design, to have a fast DAQ with a minimum dead-time. Its scheme will be described, together with some results of the performances achieved
DISTO data on Kpp
The data from the DISTO Collaboration on the exclusive pp -> p K+ Lambda
production acquired at T_p = 2.85 GeV have been re-analysed in order to search
for a deeply bound K- pp (= X) state, to be formed in the binary process pp ->
K+ X. The preliminary spectra of the DeltaM_{K+} missing-mass and of the M_{p
Lambda} invariant-mass show, for large transverse-momenta of protons and kaons,
a distinct broad peak with a mass M_X = 2265 +- 2 MeV/c^2 and a width Gamma_X =
118 +- 8 MeV/c^2.Comment: 8 pages, 4 figures. Talk presented at the "10th International
Conference on Hypernuclear and Strange Particle Physics" (HYP-X), Tokai,
Ibaraki, Japan, September 14th-18th, 2009. To appear in the proceeding
Indication of a deeply bound compact K-pp state formed in the pp -> p Lambda K+ reaction at 2.85 GeV
We have analyzed data of the DISTO experiment on the exclusive pp -> p Lambda
K+ reaction at 2.85 GeV to search for a strongly bound compact K-pp (= X) state
to be formed in the pp -> K+ + X reaction. The observed spectra of the K+
missing-mass and the p Lambda invariant-mass with high transverse momenta of p
and K+ revealed a broad distinct peak with a mass M_X = 2265 +- 2 (stat) +- 5
(syst) MeV/c2 and a width Gamma_X = 118 +- 8 (stat) +- 10 (syst) MeV.Comment: 4 pages, 4 figure
K Meson Production in the Proton-Proton Reaction at 3.67 GeV/c
The total cross section of the reaction has been determined
for proton--proton reactions with . This represents the
first cross section measurement of the channel near
threshold, and is equivalent to the inclusive cross section at
this beam momentum. The cross section determined at this beam momentum is about
a factor 20 lower than that for inclusive meson production at
the same CM energy above the corresponding threshold. This large difference in
the and meson inclusive production cross sections in proton-proton
reactions is in strong contrast to cross sections measured in sub-threshold
heavy ion collisions, which are similar in magnitude at the same energy per
nucleon below the respective thresholds.Comment: 12 pages, 3 figures Phys. Lett. B in prin
Spin physics with antiprotons
New possibilities arising from the availability at GSI of antiproton beams,
possibly polarised, are discussed. The investigation of the nucleon structure
can be boosted by accessing in Drell-Yan processes experimental asymmetries
related to cross-sections in which the parton distribution functions (PDF) only
appear, without any contribution from fragmentation functions; such processes
are not affected by the chiral suppression of the transversity function
. Spin asymmetries in hyperon production and Single Spin Asymmetries
are discussed as well, together with further items like electric and magnetic
nucleonic form factors and open charm production. Counting rates estimations
are provided for each physical case. The sketch of a possible experimental
apparatus is proposed.Comment: Presented for the proceedings of ASI "Spin and Symmetry", Prague,
July 5-10, 2004, to be published in Czech. J. Phys. 55 (2005
Production of Mesons in the Reaction at 3.67 GeV/c
The ratio of the total exclusive production cross sections for
and mesons has been measured in the reaction at
GeV/c. The observed ratio is
from which the exclusive
meson production cross section is determined to be
. Differential cross section
distributions have been measured. Their shape is consistent with isotropic
meson production.Comment: 14 pages, 5 figures, accepted by Phys.Lett.
Rho^0 meson production in the pp ->pppi+pi- reaction at 3.67 GeV/c
Total and differential cross sections for the exclusive reaction pp->pp rho^0
observed via the pi+pi- decay channel have been measured at beam momentum=3.67
GeV/c. The observed total meson production cross section is determined to be
23.4 +- 0.8 +-8 microb 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 cos^2(theta^{CM}) in the rho^0
meson production.Comment: 3 figures, 11 page
First exclusive measurements of the K^-pp state - populated in the pp to K^+ Lambda p reaction at 2.85 GeV
We have analyzed data of the DISTO experiment on the exclusive pp to K^+
Lambda p process at T_p = 2.85 MeV.Comment: 6 pages, 4 figues, Proceedings of EXA0
Fast front-end electronics for COMPASS MWPCs
In the COMPASS experiment, under construction at CERN, about 23000 channels of MWPCs will be used. The very high rate of the muon and hadron beams, and the consequently high trigger rate, require front- end electronics with innovative conceptual design. A new MWPC front- end electronics that fulfills the main COMPASS requirement to have a fast DAQ with a minimum dead-time has been designed. The general concept of the front-end cards is described; the comparative tests of two front-end chips, and different fast gas mixtures, are also shown. The commissioning of the experiment will start in the summer 2000, and production running, using the muon beam, is foreseen for the year 2001. (8 refs)