Elastic scattering of positive pions from 12C at 29 MeV

The elastic scattering cross section of positive pions at 29 MeV scattered from ¹²C has been measured at scattering angles between 15° and 150°. The cross section drops to a sharp minimum at about 40° and then rises to about 4 mb/sr at back angles.     

Investigation of the Reaction 9Be(d,t0)8Be in the Deuteron Energy Range 0.9÷2.5 MeV

The reaction ⁹Be (d, t₀) ⁸Be has been investigated in the deuteron energy range 0.9 ÷ 2.5 MeV. The excitation functions were measured at laboratory angles 45° and 120° and showed no sharp resonances. The angular distributions (differential cross sections in mb/sr) were measured in 200 keV intervals. An analysis of the data has been made using the Butler and the distorted wave theories.     

The reaction 14C(3He,n)16O and the coexistence model of 16O

The reaction ¹⁴C(³He, n)¹⁶O has been measured at a ³He bombarding energy of 25.4 MeV. The zero-degree differential cross section for the excitation of the three low lying 0⁺T = 0 states, at energies 0.0, 6.05 and 12.05 MeV are, respectively, 1.33 ± 0.10, 0.49 ± 0.10, and 0.50 ± 0.10 mb/sr These measured cross sections are in rough agreement with single-step zero-range DWBA calculations using an empirically determined ¹⁴C ground state wave function and in which the Brown and Green coexistence-model wave functions are used to describe the ¹⁶O 0⁺ states. The angular distribution of the transition to the ground state is measured between 0° and 32°.     

Fission cross section and fragment angular distribution in gold fission induced by 55 MeV alpha particles using solid state nuclear track detectors

The angular distribution of fission fragments in alpha induced fission has been studied at an incident energy of 55 MeV in¹⁹⁷Au target. The relative differential fission cross sections were measured at different angles between 10° and 170° and the resulting angular distributions fitted by least squares method with Legendre polynomials. In the present work, a correction for the self-scattering and self-absorption of fission fragments in the target itself was applied and a target of 3 mg/cm² was used to get good statistics. The anisotropy for 55 MeV alpha induced fission of gold was 2·83±0·43 and the fission cross section calculated by integrating the measured angular distributions over all the solid angles was 5·2±1.0 mb, confirming the value of 4·0±0·05 mb reported by Burnettet al but contrary to the high value of 10±3 mb reported by Ralarosyet al.     

The C(α, X)11C cross sections at 1.59 and 4.19 GeV

The absolute cross sections for the production of ¹¹C by 1.59 GeV and 4.19 GeV α-particles incident on natural carbon have been measured to be 46.4 ± 1.3 mb and 42.5 ± 1.1 mb respectively. These results, together with data reported at other energies, indicate that the C(α, X)¹¹C cross section becomes approximately constant at a value of about 43 mb for energies above 3 GeV (750 MeV/n). A similar energy dependence is exhibited by the C(p, X)¹¹C reaction whose cross section has been measured previously over an extensive energy range. The C(α, X)¹¹C cross sections are found to be in good agreement with predictions of a semi-empirical model developed to describe nuclear fragmentation.     

Measurements of the π−p → π0n forward scattering cross section in the energy region 400–600 MeV

The forward charge-exchange differential cross section has been measured using two ?erenkov spectrometers at five energies of incident pions. The resulting cross-section values are 4.02 ± 0.22, 3.61 ± 0.13, 4.19 ± 0.13, 3.91 ± 0.12, 3.02 ± 0.14 mb/sr at incident pion energies 400, 450, 500, 550 and 600 MeV, respectively. These values are in a good agreement with dispersion-relation predictions.     

Messung der Neutronenpolarisation bei der Reaktion12C(d,n 0)13N mit Hilfe der Mott-Schwinger-Streuung

The polarization of neutrons produced in the reaction¹²C(d, n ⁰)¹³N was measured. Deuterons from the Karlsruhe isochronous cyclotron were used to induce this reaction at 51,5 MeV laboratory energy. The degree of polarization was determined by using the special features of Mott-Schwinger scattering. With an uranium scatterer analysing efficiencies of up to 0.92 can be obtained at very small angles (0.23°). The analysing efficiency can be calculated if the differential cross section at 0° and the total cross section is known. These quantities were experimentally determined. The differential cross section for 49.4 MeV neutrons, scattered by uranium, was measured between 0.88° and 2.10°. By an extrapolation the value 43.4±2.6 b/sr was found for the nuclear differential cross section at zero degree. A total cross section ofσ _t=4.80±0.22 b was obtained. The neutron polarization was measured at a reaction angle of 24.5° and the result isP=?0.45±0.07. This value is fairly above the semiclassical 1/3 limit and can be only explained, if spin orbit forces are taken into account. For (d, n) reactions this is the first neutron-polarization measurement above an energy of 20 MeV.     

K−π− elastic scattering cross section measured in 14.3 GeV/c K−p interactions

Results are presented on a measurement of the I = 3/2 Kπ elastic scattering cross section by applying the Chew-Low extrapolation method in the reaction K^?p → K^?π^?Δ⁺⁺at14.3GeV/c. The magnitude of σ(K^?π^? → K^?π^?) is found to be about 3 mb at threshold and slowly falling with energy to about 1.5 mb at 2.8 GeV. The off-mass-shell moments of the differential elastic cross section are given. The absolute value of δ₃⁰ is found to be increasing slowly from 0° to 20° between threshold and 1.2 GeV.     

Nuclear resonant scattering of annihilation quanta

Resonant scattering by ¹⁰⁶Pd nuclei of γ-quanta produced by positron annihilation in metallic copper has been observed. The differential cross section of this process for a scattering angle of 120° was found to be 0.27 ± 0.05 mb/sr.     

Investigation of the role of the projectile-target orientation angles on the evaporation residue production

The measured yield of evaporation residues in reactions with massive nuclei have been well reproduced by using the partial fusion and quasifission cross sections obtained in the dinuclear-system model. The influence of the orientation angles of the projectile- and target-nucleus symmetry axes relative to the beam direction on the production of the evaporation residues is investigated for the ⁴⁸Ca + ¹⁵⁴Sm reaction as a function of the beam energy. At the low beam energies only the orientation angles close to αP = 30° (projectile) and αP = 0°–15° (target) can contribute to the formation of evaporation residues. At large beam energies (about E _c.m. = 140–180 MeV) the collisions at all values of orientation angles αP and α _T of reactants can contribute to the evaporation residue cross section which ranges between 10–100 mb, while at E _c.m. > 185 MeV the evaporation residue cross section ranges between 0.1–1 mb because the fission barrier for the compound nucleus decreases by increasing its excitation energy and angular momentum.     

Experimentelle Untersuchungen der Reaktionenp (d,pp) n undd (d,dp) n mit 51,5 MeV Deuteronen

The external beam of 51.5 MeV deuterons from the Karlsruhe isochronous cyclotron was used to investigate the three particle reactionsp(d,pp)n andd(d, dp)n. A kinematically complete experiment was performed by detecting the two emitted protons respectively the proton and the deuteron in coincidence. The data for the reactionp (d, pp) n exhibit a pronounced final state interaction between the outgoing neutron and one proton. This final state interaction is mainly due to then— p singlet interaction and the extractedn— p scattering length is ¦a_s¦=(19±2.5) fm. In the investigation of the reactiond(d, dp)n the angles were chosen as to observe quasielastic deuteron-proton-scattering predominantly. The data was analysed in terms of the Chew Low Spectator model and we obtained by “on-energy-shell” extrapolation for thed?p cross section the value (7±2.5) [mb/sr]. This value has to be compared with the cross section for freed?p scattering which was independently measured and the value obtained for the corresponding angle is (16±1) [mb/sr].     

Near threshold production of neutral pions by complex particles

Cross sections for the inclusive neutral pion production cross section have been measured for near threshold energy ³He particles on complex nuclei. The results of these measurements are of order 10^?36 cm²/sr · MeV. The neutral pion cross section for 710 MeV ⁴He on ¹²C has been found to be comparable to the production cross section for nucleons, 10^?30 cm²/sr · MeV. Comparisons are made with a naive model relating complex particle production to nucleon production of pions.     

Search for coulomb fission induced by 84Kr ions on 238U

We have searched for Coulomb fission induced by ⁸⁴Kr ions on a ²³⁸U target at energies ranging from the interaction barrier down to 37 MeV below (408–458 MeV lab). No event attributed to Coulomb fission was detected; it was deduced that the cross section for this reaction is lower than 0.3 mb/sr near the interaction barrier. This value was compared to theoretical predictions. However, fission events originating from transfer reactions at the interaction barrier have been detected.     

Inclusiveπ° production in 360 GeVpp interactions using the european hybrid spectrometer

The intermediate and forward gamma detectors of EHS are used to reconstructπ°'s produced by 360 GeV/cpp interactions in the Rapid Cycling Bubble Chamber (RCBC). Using thepp forwardbackward symmetry, the inclusiveπ° production cross section is obtainedσ _π°=(132±11) mb. The averageπ° multiplicity is determined as a function of the charged particle multiplicity. The (1?x) dependence is given for differentp _T regions.     

The nonelastic projectile break-up cross section from particle-gamma coincidence measurements for the 6li + 40ca reaction at 156 mev

The cross sections for nonelastic break-up modes have been studied for the ⁶Li + ⁴⁰Ca reaction at E_Li = 156 MeV. Gamma-ray spectra from target-like residual nuclei were measured in coinci- dence with beam-velocity projectile fragments and a value for the nonelastic break-up cross section σ^b.u_non = 582 ± 110 mb has been found. Together with results of inclusive charged-particle measure- ments we infer for the total break-up cross section σ^b.u_tot = 930 ± 115 mb comprising about 50% of the total reaction cross section. The nonelastic contribution of the break-up reaction appears to be less than predicted by the DWBA break-up theory. This result is directly evident from the differential cross sections by comparing inclusive and exclusive results.     

Measurement of theΞ - p elastic cross section at 102 and 135 GeV/c

TheΞ ^- p differential elastic cross section has been measured in the SPS hyperon beam at 102 and 135 GeV/c. In the range 0.012, thet distributions are found to be compatible with the formA exp(Bt) whereB is 7.7±0.4(GeV/c)^?2 at 102 GeV/c and 8.2 ±0.5(GeV/c)^?2 at 135 GeV/c. The corresponding total elastic cross sections areσ _el=4.9±0.7 mb andσ _el=5.6±0.9 mb, respectively. These results are compared with the predictions of phenomenological models.     

Sensitive search for neutral resonances in Bhabha scattering around 1.8 MeV/c2

The excitation function for Bhabha scattering was measured in the energy range between 760 and 840 keV (CM) in 1.4 keV steps with beams of monochromatic positrons scattered on a Be foil at angles between 79° and 101° (CM). The statistical accuracy was 0.5%. Up to an upper limit of 1.0 b eV/sr (CM) for the energy-integrated differential cross section (97% CL) no resonant scattering was observed. This limit corresponds to a maximal resonance contribution of 0.7% relatively to the Bhabha cross section, consistent with the upper bound, derived from precision measurements of the electron (g-2) factor.     

Observation of the nuclear rainbow scattering for12C+12C atE Lab =300 MeV

The elastic and inelastic scattering of¹²C on¹²C has been measured in the angular range between 2.8° and 70.4° in the c.m. system atE _Lab =300 MeV. Optical model calculations have been performed with Woods-Saxon and folded potentials, the ground state and the first 2⁺-state were coupled in the calculations. The large cross sections of the elastic scattering at large angles is related to the nuclear rainbow scattering, which is centered at about 56°. This requires a potential depth of 100 MeV at a distance of 3 fm, the fit to the data is sensitive down to this region. The calculations with the folded potential show a better agreement with the data than those with the Woods-Saxon shape. The total reaction cross section of 1,420 mb, obtained from the optical model analysis, corresponds to the geometrical value; no transparency is observed.     

Charged particle multiplicities in 100 GeV/cpp interactions

Results are presented on the topological cross sections obtained for antiproton-proton interactions from an exposure of the Fermilab 30-inch bubble chamber to a 100 GeV/c negative beam enriched in $\text{p}$'s. The $\text{p}$p inelastic cross section is found to be σ_inel = 34.6 ± 0.4 mb, and the average inelastic charged particle multiplicity to be 〈n〉 = 6.74 ± 0.05.     

Structure en bande du noyau 22Na: Le premier niveau Jπ = 6+

We investigate the two-body photodisintegration of ³He and its inverse, radiative p-d capture using bound-state functions corresponding to the N-N interaction being given by the Reid soft-core potential. For the two-body photodisintegration of ³He Coulomb effects and the final-state interactions between the proton and deuteron are not included. At low energy the shape of the angular distribution agrees well with experiment, but the 90° cross section exhibits an anomalous peak at 15 MeV due to electric dipole transitions connecting the deuteron and ³He D-states. The low-energy cross section is 25–40 % too small. The intermediate-energy angular distribution peaks too near the forward direction, and, contrary to experiment, has a minimum at 100°. At higher energy the 90° cross section in the center-of-momentum frame is at least an order of magnitude too small, but does display the correct energy dependence. This energy dependence is related to the properties of the bound-state wave functions and it is plausible that it will persist in an improved treatment (e.g. one which includes exchange currents) which properly accounts for the magnitude of the cross section. Contributions from the ³He S-states are negligible for photon energies between 100 and 150 MeV, but are dominant outside this energy region.