The Indiana Silicon Sphere 4π detector has been used to measure light-charged particles and intermediate-mass fragments (IMFs) emitted in the 18–4.8 GeV He3+natAg, Au197 reactions. Ejectile multiplicity and total event kinetic energy distributions scale systematically with projectile energy and target mass, except for the Agnat target at 3.6 and 4.8 GeV. For this system, a saturation in deposition energy is indicated by the data, suggesting the upper projectile energy for stopping has been reached. Maximum deposition energies of ∼950 MeV for the Agnat target and ∼1600 MeV for the Au197 target are inferred from the data. The results also demonstrate the importance of accounting for fast cascade processes in defining the excitation energy of the targetlike residue. Correlations between various observables and the average IMF multiplicity indicate that the total thermal energy and total observed charge provide useful gauges of the excitation energy of the fragmenting system. Comparison of the experimental distributions with intranuclear cascade predictions shows qualitative agreement. © 1996 The American Physical Society.
TARGET IS NATURAL AG.
No description provided.
The analyzing power Ay for π+p→ scattering at 68.3 MeV has been measured at the Paul Scherrer Institut with the magnetic spectrometer LEPS. The measurements cover the angular range 40°≤θlab≤70°. The protons have been polarized in a butanol target, operated in frozen spin mode. The S31 phase shift comes out by about 1° smaller than the Koch-Pietarinen [Nucl. Phys. A 336, 331 (1980)] phase shift analysis, supporting the necessity of an alternative dispersion analysis of πN scattering to determine the σ term and the πN coupling constant. © 1996 The American Physical Society.
The two data sets correspond to measurements with two different target compositions (see text).
Multifragmentation of Agnat and Au197 nuclei induced by 1.8–4.8 GeV He3 ions has been studied with the Indiana Silicon Sphere 4π detector array. Rapidity, moving source, and sphericity-coplanarity analyses are consistent with near-simultaneous emission from a source in approximate kinetic equilibrium. For the most dissipative collisions, the spectral peaks are broadened and shifted to very low energies, indicative of emission from an extended nuclear system with ρ/ρ0∼1/3. Predictions of an intranuclear cascade/expanding, emitting source model compare well with experimental multiplicity distributions and the evolution of fragment spectral shapes. © 1996 The American Physical Society.
No description provided.
No description provided.
The frequency of the protonium annihilation channel p p → K S K L has been measured at three different target densities: liquid hydrogen ( LH ), gaseous hydrogen at NTP conditions and gaseous hydrogen at low pressure (5 mbar). The obtained results are: f( p p → K S K L , LH) = (7.8 ± 0.7 stat ± 0.3 sys ) × 10 −4 , f( p p → K S K L , NTP) = (3.5 ± 0.5 stat ± 0.2 sys ) × 10 −4 and f( p p → K S K L , 5 mbar ) = (1.0 ± 0.3 stat ± 0.1 sys ) × 10 −4 . Since the K S K L final stat and be originated only from the 3 S 1 initial state, these values give direct information on the scaling of the protonium spin-triplet S-wave annihilation probability with the density.
Three different target densities: liquid hydrogen (LH), gaseous hydrogen atstandard temperature and pressure conditions (NTP), and gaseous hydrogen at 5 m bar pressure (LP). The annihilation proceeds only from 3S1 initial state.
In explosive stellar hydrogen burning, the hot CNO cycles and the rp-process are mainly linked by the reaction sequence 15 O(α, γ) 19 Ne(p,γ) 20 Na. Using intense 19 Ne radioactive beams, both the 19 Ne(p,γ) and the 19 Ne(d,n) reaction have been studied. Upper and lower limits for the 19 Ne(p,γ) reaction rate have been deduced, allowing to conclude that the 15 O(α,γ) reaction is most likely the bottleneck reaction.
Two target were used: polyethylene foil (C=CH2) and static gas cell (C=H2).Two different detection set-ups have been designed: the Solid State Nuclear Tra ck Detector (C=SSNTD) method and the Solenoid and Telescope (C=STAR) method.
A study of the reactions p Xe → K + K + X , p Xe → K + H(H → Σ − p)X and p Xe → K + K + H(H → Σ − p)X was performed using the 700-litre xenon bubble chamber DIANA, exposed to the 1 GeV/ c antiproton beam of ITEP (Moscow). From a sample of 7.8 · 10 5 antiproton annihilations at low energy in xenon nuclei 4 events were observed for the reaction p Xe | → K + K + X at rest ( P p ≤ 400 MeV /c ) and 8 for the same reaction in flight ( 400 ≤ P p ≤ 900 MeV /c ). The corresponding probabilities turned out to be 3.1 · 10 −5 and 3.4 · 10 −5 , respectively. No H -event was found in the two semi-inclusive reactions p Xe → K + HX and p Xe → K + K + HX . This lead to the upper limits 6 · 10 −6 and 8 · 10 −6 (90% C.L.), respectively. The corresponding upper limit for the fully inclusive reaction p Xe → HX turned out to be 1.2 · 10 −5 (90% C.L.), which is about one order of magnitude lower than the actual value reported in the literature.
No description provided.
Differential cross sections for p p elastic scattering have been measured for very small momentum transfers at six different incident antiproton momenta in the range 3.7 to 6.2 GeV/c by the detection of recoil protons at scattering angles close to 90°. Forward scattering parameters σ T , b , and ϱ have been determined. For the ϱ-parameter, up to an order of magnitude higher level of precision has been achieved compared to that in earlier experiments. It is found that existing dispersion theory predictions are in disagreement with our results for the ϱ-parameter.
Results of the SIG(T)-free analysis. Errors include systematic uncertainties.
Results of the SIG(T)-fixed analysis. Errors include systematic uncertainties.
CT values of the total cross section from the SIG(T)-free analysis. Errors include systematic uncertainties.
We present the first experimental study of the ratio of cumulant to factorial moments of the charged-particle multiplicity distribution in high-energy particle interactions, using hadronic Z$^0$ decays collected by the SLD experiment at SLAC. We find that this ratio, as a function of the moment-rank $q$, decreases sharply to a negative minimum at $q=5$, which is followed by quasi-oscillations. These features are insensitive to experimental systematic effects and are in qualitative agreement with expectations from next-to-next-to-leading-order perturbative QCD.
CONST is the cumulant to factorial moments ratio. See text for definition.
We present asymmetries between the production of D+ and D- mesons in Fermilab experiment E791 as a function of xF and pt**2. The data used here consist of 74,000 fully-reconstructed charmed mesons produced by a 500 GeV/c pi- beam on C and Pt foils. The measurements are compared to results of models which predict differences between the production of heavy-quark mesons that have a light quark in common with the beam (leading particles) and those that do not (non-leading particles). While the default models do not agree with our data, we can reach agreement with one of them, PYTHIA, by making a limited number of changes to parameters used.
Asymmetry parameter A = (SIG(D-)-SIG(D+))/(SIG(D+)+SIG(D-)) have been studied as function of Feynman variable X. 'Nucleus' are PT and C.
Asymmetry parameter A = (SIG(D-)-SIG(D+))/(SIG(D+)+SIG(D-)) have been studied as function of PT**2. 'Nucleus' are PT and C.
Asymmetry parameter A = (SIG(D-)-SIG(D+))/(SIG(D+)+SIG(D-)) have been studied as function of PT**2. 'Nucleus' are PT and C.
A new measurement of the total e + e − → hadrons cross-section in the centre of mass energy range 1.8-2.5 GeV, performed by the FENICE experiment at the Frascati e + e − storage ring ADONE, is presented. The behaviour of the total cross section together with the proton electromagnetic time-like form factor is discussed in terms of a narrow vector resonance close to the nucleon-antinucleon threshold.
Only statistical errors are quoted.
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