J.P. Guillaud

A new measurement of the beta emission asymmetry in the free decay of polarized neutrons

Abstract The beta asymmetry coefficient A0 was measured in the free decay of polarized neutrons by means of a time projection chamber in coincidence with plastic scintillators. A value of A0 = −0.1160(15) was measured and λ = g A g V = −1.266(4) deduced. Including recent results on the neutron lifetime the weak interaction coupling constants were determined as gV = 1.4172(34) × 10−62 J m3 and gA = −1.7944(20) × 10−62 J m3. The gV value is in excellent agreement with those from ft(0+ → 0+) and muon decay.

J/ψ and ψ′ production in p, O and S induced reactions at SPS energies

Abstract The production of the J/ ψ and ψ ′ charmonia states has been studied, through their dimuon decay, in proton, Oxygen and Sulphur induced reactions, by the NA38 experiment at the CERN SPS. The proton data was collected with beams of 200 and 450 GeV, while the ion beams had an energy of 200 GeV per incident nucleon. The J/ ψ production cross-section per nucleon-nucleon collision exhibits a remarkably continuous pattern, as a function of the product of the mass numbers of the interacting nuclei, from pp up to S-U reactions. The same pattern is observed within S-U collisions, as a function of the collision centrality. While in p-A interactions both charmonia states exhibit the same A-dependence, in S-U collisions the ψ ′ production is very strongly suppressed.

J/ψ, ψ′ and Drell-Yan production in S-U interactions at 200 GeV per nucleon

Abstract A detailed study of J/ ψ , ψ ′ and Drell-Yan production in S-U collisions has been performed by experiment NA38 at the CERN SPS. This paper presents production cross sections and their centrality dependence, based on the largest sample of S-U events collected by the experiment.

Charmonia production in 450-GeV/c proton induced reactions

Absolute \jpsi\ and \psip\ production cross sections have been measured at the CERN SPS, with 450~GeV/

The measurement of the beta asymmetry in the decay of polarized neutrons

c

Antinuclei production in Pb + Pb collisions at 158 A GeV/c

protons incident on a set of C, Al, Cu and W targets. Complementing these values with the results obtained by experiment NA51, which used the same beam and detector with H and D targets, we establish a coherent picture of charmonia production in proton-induced reactions at SPS energies. In particular, we show that the scaling of the \jpsi\ cross section with the mass number of the target, A, is well described as A

Baryon and antibaryon production in lead-lead collisions at 158 A GeV/c

^\alpha

Strangelet search and particle production studies in Pb + Pb collisions

with

Initial state interactions and J/ψ production in nucleus-nucleus collisions

\alpha^\psi=0.919\pm0.015

Jψ, ψ′ and muon pair production in p-W and S-U collisions

. The ratio between the \jpsi\ and \psip\ yields, in our kinematical window, is found to be independent of A, with