Polarization of protons scattered from C12

The polarization of protons elastically scattered from carbon in the energy region between 4.65 and 5.0 Mev has been measured by double scattering from carbon targets. These results, together with the findings at Harwell by Evans and Grace, show that the polarizations predicted from the phase shift analysis are somewhat in error. This disagreement may be explained by making small changes in the splitting of the P- and D-wave phase shifts without seriously affecting the fit to the angular distributions. It was found that in the energy range from 3.0 to 4.0 Mev the D-wave phases required from 1° to 4° additional splitting, while in the range from 4.0 to 5.0 Mev the splitting of the P-wave phases had to be reduced by 4°. These modified phase shifts give a revised contour map of spin polarization versus energy and angle

The pi N -> pi pi N reaction around the N(1440) energy

We study the pi N -> pi pi N reaction around the N(1440) mass-shell energy. Considering the total cross sections and invariant mass distributions, we discuss the role of N(1440) and its decay processes. The calculation is performed by extending our previous approach [Phys. Rev. C 69, 025206 (2004)] to this reaction, in which only the nucleon and Delta(1232) were considered as intermediate baryon states. The characteristics observed in the recent data for the pi- p -> pi0 pi0 n reaction obtained by Crystal Ball Collaboration (CBC), can be understood as a strong interference between the two decay processes: N(1440) -> pi Delta(1232) and N(1440) -> N(pi pi)_S. It is also found that the scalar-isoscalar pi pi rescattering effect in the NN*(pi pi)_S vertex, which corresponds to the propagation of sigma meson, seems to be necessary for explain ing the several observables of the pi N -> pi pi N reaction: the large asymmetric shape in the pi0-pi0 invariant mass distributions of the pi- p -> pi0 pi0 n reaction and the pi+ p -> pi+ pi+ n total cross section.Comment: 28 pages, 13 figures. Version to appear in Phys. Rev.

Search for a periodic signal from Cygnus X-3 usingmuons observed underground in the Frejus detector (4800 mwe)

Periodic signals from Cygnus X-3 in the ultra high energy range were recently reported by air shower arrays and attributed to gamma rays. Although gamma rays are expected to produce muon-poor showers, the preceding observations have stimulated similar studies based on underground muons. Two groups have claimed a significant underground signal coming from Cygnus X-3. The results are, however, extremely difficult to explain in the present framework of particle physics, and clearly need confirmation. The preliminary results obtained from the Frejus underground detector during its first 16 months of operation (March 1984 to June 1985) are presented

New limits on nucleon decays into invisible channels with the BOREXINO Counting Test Facility

The results of background measurements with the second version of the BOREXINO Counting Test Facility (CTF-II), installed in the Gran Sasso Underground Laboratory, were used to obtain limits on the instability of nucleons, bounded in nuclei, for decays into invisible channels ($inv$): disappearance, decays to neutrinos, etc. The approach consisted of a search for decays of unstable nuclides resulting from $N$ and $NN$ decays of parents $^{12}$C, $^{13}$C and $^{16}$O nuclei in the liquid scintillator and the water shield of the CTF. Due to the extremely low background and the large mass (4.2 ton) of the CTF detector, the most stringent (or competitive) up-to-date experimental bounds have been established: $\tau(n \to inv) > 1.8 \cdot 10^{25}$ y, $\tau(p \to inv) > 1.1 \cdot 10^{26}$ y, $\tau(nn \to inv) > 4.9 \cdot 10^{25}$ y and $\tau(pp \to inv) > 5.0 \cdot 10^{25}$ y, all at 90% C.L.Comment: 22 pages, 3 figures,submitted to Phys.Lett.

PRESENTATION OF THE HADRON SPECTROSCOPY PARALLEL SESSIONS

At this Conference, four parallel sessions have been devoted to Hadron Spectroscopy. As a matter of fact, the limits of this topic are not well defined. Clearly the baryon and meson resonances results obtained in formation and production experiments constitute a part of Hadron Spectroscopy ; furthermore it seems reasonable that the meson or baryon diffractive enhancements which are more and more believed now to be non resonant should also be discussed in this session. However it is almost impossible to separate the study of the nature and spin parity properties of these objects from the study of their production mechanism ; a large overlap is therefore unavoidable with the session 8 where these mechanisms are discussed. In the same way, the mini-rapport of Dr. Faiman (session 6), where the new theoretical idea concerning the baryon classification are presented is obviously strongly connected with Hadron Spectroscopy. Finally, I would like to apologize for the numerous interesting theoretical papers (papers n° 211, 322, 323, 32, 89, 233, 234, 373) which also deal with this session and have not been reported therein by lack of space, and I suggest that the specialists consult them directly

Study of strong interactions at high energy in bubble chambers

The high energy bubble chamber experiments performed at DPhPE are devoted to the K/sup -/p interaction at 14.3 GeV/c, K/sup +or-/p at 32 GeV/c and pp at 69 GeV/c. The pictures are taken in the 2 meters bubble chamber at CERN and in the 4.5 meters, Mirabelle, at Serpukhov. The reactions which are studied are on one hand, two body or quasi two body reactions, and on the other hand, the multibody reactions. The first ones are dominated by diffractive processes in which one of the incident particle remains in its initial state while the other one is fragmented into a few particles. The second kind of reactions, whose contribution increases with energy, are studied by means of the momentum distributions of a single well defined particle; these distributions are compared to the theoretical scaling predictions. (16 refs)

Radioactivité de 159Gd. Étude d'états excités de 159Tb

A γ transition of 222 keV in [FORMULE]Tb is coincident with two transitions, probably the 81 and 58 keV previously known. A very weak transition of about 300 keV is also observed. The ratio of α K coefficients of these two transitions and the relative intensities of 364, 222 and about 300 keV γ(100-2,5-0,5) are roughly measured. These intensities are in discordance with the calculated branching ratios (Alaga et al.) if these three transitions have the same initial state (hypothesis compatible with the measured energies). The mean life of 364 keV state is [FORMULE]s. The 58 keV transition is chiefly in coincidence with a β spectrum of about 950 keV.Une transition γ de 222 keV dans [FORMULE]Tb coïncide avec deux transitions, probablement celles déjà connues de 81 et 58 keV. Une transition très peu intense d'environ 300 keV est aussi observée. Le rapport des αK de ces deux transitions est grossièrement mesuré, ainsi que les intensités relatives des γ de 364, 222 et environ 300 keV (100-2,5-0,5). Ces intensités sont en désaccord avec les rapports d'embranchement calculés (Alaga et al.) si ces trois transitions ont le même état initial (hypothèse compatible avec les énergies mesurées). La vie moyenne de l'état à 364 keV est inférieure à, ou voisine de [FORMULE]s. La transition de 58 keV coïncide surtout avec un spectre β d'environ 950 keV