Search

Collective excitations in the two-particle nucleus148Gd up to 2.9 MeV have been investigated by thepp′-reaction at 25 MeV beam energy, and angular distributions have been analyzed with standard DWBA calculations. It is found that148Gd has larger octupole- than quadrupole collectivity in the energy range investigated. The 3− strength distribution is in quantitative agreement with predicted results for the levels formed by the coupling of two valence particles to the146Gd core octupole phonon.

Approximately 350 A2+ events have been observed in the reaction π + p → K + K S 0 p ( K S 0 → π + π − ) at an incident π+ laboratory momentum of 12.7 GeV/c. The events are distributed over a range of four-momentum transfer squared 0.01 ⩽ −t ⩽ 0.60 (GeV/c)2 and K + K S 0 mass 1.11 ⩽ m K + K S 0 ⩽ 1.51 GeV . A Breit-Wigner fit to the mass spectrum yields a mass for the A2+, mA2+ = 1.324 ± 0.005 GeV, and a width Γ0 = 0.110 ± 0.018 GeV. We find a cross section σ (π+p → A2+p) = 1.71 ± 0.30 μb referring to the above-mentioned mass and t range and A 2 + → K + K S O with K S 0 → π + π − . The spin-space density matrix in the Gottfried-Jackson frame is practically saturated by ϱ 11 ⋍ ϱ 1−1 = 1 2 suggesting natural parity exchanges only. There is a forward dip in the angular distribution consistent with dominance of s-channel net helicity flip amplitudes and ϱ and f Regge exchanges suffice to describe adequately our differential cross sections.

Differential cross sections for the 209Bi(d, 3He)208Pb transitions to the proton particle-proton hole states in 208Pb were obtained with the 45 MeV analyzed deuteron beam from the JULIC cyclotron and the high resolution spectrograph BIG KARL. 72 states up to 6.6 MeV were studied with an overall resolution of 12 to 15keV. Spectroscopic factors were extracted relative to the simultaneously measured calibration reaction 208Pb(d, 3He)207Tl. For 26 states new parity assignments were possible on the basis of the measured angular distributions. The deduced inclusion into one of the four multiplets put limits on the possible spins of the states in question. With the help of sum rule arguments the spins of 12 states were assigned. The comparison with shell model calculations give only rough agreement as they predict the energies of the respective states about 300 keV too high. The magnetic dipole state at 5.846 MeV was observed with a Spectroscopic factor C2S = 0.17. From this, together with the transition probability B(M1↑) = (1.6 ± 0.5) μN2 from a ( γ , γ′) experiment we derived size and relative sign of the dominant neutron and proton spin-flip amplitudes. The result gives clear evidence for the isoscalar character of this state in accordance wtih TDA and RPA predictions. The matrix elements of the two-body residual interaction were derived unambiguously for the h 9 2 ∗ s 1 2 and h 9 2 ∗ d 3 2 multiplets. For the h 9 2 ∗ h 11 2 and h 9 2 ∗ d 5 2 multiplets uncertainties are larger because of assumptions of some of the spins for the states of high excitation energy. The four monopole terms are found close to the average of −308 keV. They are dominated by the Coulomb contributions of ≈ − 216 keV. The deduced J-dependence of the matrix elements differs from those found in other systematic investigations indicating more complicated underlying nuclear forces must contribute.

The giant octupole resonance has been investigated for heavy nuclei ( A ⩾ 120) in 172 MeV α scattering at scattering angles between 3° and 5°. For deformed rare earth and actinide nuclei an increase in width (up to ∼ 2 MeV) and a shift in centroid energy (of about 1 MeV) have been found. The energy shift was opposite in the rare earth and actinide region indicating different nuclear structure effects.

The t-dependence of ϱ, f and g resonance production is compared using data from the CERN-Munich spectrometer. An amplitude analysis is performed, and the significance for various proposed models of the production mechanism discussed. The OPE term becomes increasingly adequate to describe the data as the resonant mass increases.

A detailed account is given of a high statistics experiment measuring the reaction π−p→π−π+n at 17.2 GeV/c. The spark chamber and counter triggering system are desribed. The methods of data analysis are described, in particular the determination of angular distributions from apparatus with limited acceptance. Experimental data and their interpretation are presented.

Two delay-line readout drift chambers with an active area of 90 cm by 7 cm are now in use as focal plane detectors at the high resolution spectrometer Big Karl. The position resolution is better than 0.2 mm fwhm with detector efficiencies exceeding 99.5% for 45 MeV deuterons. Light ions such as protons, deuterons, alphas and others up to 6He have been measured at energies between 15 and 45 Mev per nucleon. The new detector offers a significantly higher focal plane acceptance with improved background suppression and correction capabilities.

We report the observation of a spin 4 resonance from the analysis of the reaction π − p→ K + K − n. The mass and width of the h-meson were determined to be 2050 MeV and 225 MeV. The quantum numbers are J P = 4 + , C = +1 and very probably I G = 0 + .

The 58 Ni(d, 3 He) 57 Co reaction was measured at a bombarding energy of 78 MeV. Energy levels up to 7.0 MeV excitation energy in 57 Co were studied. Angular distributions of the 3 He particles, corresponding to transitions to the ground state and to 42 excited states in 57 Co, were analyzed in the range of θ lab = 2.7° to 25°. Exact finite-range DWBA calculations were employed to extract l -values and spectroscopic factors. Shell-model calculations were carried out in an fp-shell model space. In addition, calculations of the energy levels in 57 Co were performed in the SU(6) particle-vibration model (PTQM). Satisfactory agreement is observed between the experimental results and both theoretical predictions.

Results of two spark chamber experiments on A2− production in the reaction π−p → K−KS0 (→ π+π−)p at 9.8 and 18.8 GeV are presented. Decay angular distributions and differential cross sections are given, and the energy dependence of the cross section σ[π−p → A2−(→ K−K0)p] is compared with results from π−p → A2−(→ 3π)p.

Angular distributions of the 12 C(d, 6 Li) 8 Be reaction at E lab = 78.0 MeV and the 11 B( 3 He, 6 Li) 8 Be reaction at E lab = 71.8 MeV were measured. Transitions leading to 8 Be in the ground state and the 3.04, 16.63, 16.92, 17.64 and 18.15 MeV excited states were observed. A DWBA analysis was performed regarding the (d, 6 Li) and ( 3 He, 6 Li) reactions as direct α particle or triton transfers, respectively.

Angular distributions of the 11 B( 3 He, 7 Li) 7 Be reaction were measured in the entire angular region at 71.8 MeV beam energy yielding information on the 4 H-like cluster transfer in the forward direction and α-cluster transfer in the backward region. A DWBA analysis including processes up to the second order indicates a rather small yield of 4 H transfer and a dominant two-step transfer mechanism in the ( 3 He, 7 Li) reaction.

Fractions of equilibrium singly charged 3 He 1+ ions produced by 3 He 2+ beams going through carbon targets were measured at 68, 99 and 130 MeV incident energies. The thickness dependence of the 3 He 1+ / 3 He 2+ fraction was measured, which allowed to deduce the electron capture cross section. The experimental results are compared with the first and higher order Born approximation theories.

The ππ phase shifts from 1 to 1.8 GeV are presented. The method used was an essentially energy-independent parametrization of the amplitudes fitted simultaneously to the M ππ and t -dependence of the moments of the dipion angular distribution from the reaction π − p → π − π + n at 17.2 GeV. The various ambiguous solutions are discussed.

Experimental evidence is presented that the144Nd(p, α)141Pr reaction excites residual nucleus levels with a dominant single proton configuration, suggesting a contribution from knock-on mechanism.

Differential cross sections of the $^{48}\mathrm{Ca}$($p$,${p}^{\ensuremath{'}}$) (${1}^{+}$, 10.212 MeV) transition have been measured at ${E}_{p}=44.4$ MeV using an isochronous cyclotron and a high resolution magnetic spectrometer. The data are compared to microscopic distorted-wave Born approximation calculations with wave functions taken from random phase approximation calculations.NUCLEAR REACTIONS $^{48}\mathrm{Ca}$($p$,${p}^{\ensuremath{'}}$), $E=44.4$ MeV; measured $\ensuremath{\sigma}(E;\ensuremath{\theta})$; microscopic DWBA analysis, resolution 7-10 keV; $\ensuremath{\theta}=7.3\ensuremath{-}80.0\ifmmode^\circ\else\textdegree\fi{}$, $\ensuremath{\Delta}\ensuremath{\theta}=4\ensuremath{-}5\ifmmode^\circ\else\textdegree\fi{}$.

Results of an analysis of two high-statistic samples of pp events (10 700 events at plab = 18.8 GeV and 35 000 events at plab = 18.4 GeV) are presented. The data extend from threshold to 2.8 GeV invariant mass. The production proceeds dominantly via one-pion exchange with absorption corrections. The mass spectrum and decay angular distribution can be explained as a superposition of resonating partial waves with spin J = 2, 3, 4, 5,. Indications of a spin-6 state at 2.71 GeV are found.

In a high resolution (p,p′) experiment at E=25.5MeV, the complete particle-core coupled multiplet (3 − · f 7 2 ) J in the N=83 143Nd nucleus has been identified and the spins of its members assigned. The experimental results are discussed in connection with the observed large energy splitting of about 650 keV. The comparison with the corresponding multiplet observed in 146Gd is a new strong indication for the shell closure at Z=64.

Inelastic excitation of giant resonances has been studied in 172 MeV $\ensuremath{\alpha}$ scattering from $^{208}\mathrm{Pb}$ at scattering angles of 1.5\ifmmode^\circ\else\textdegree\fi{}-8\ifmmode^\circ\else\textdegree\fi{}. Fine structures in the region of the giant monopole and quadrupole resonances indicate multipolarities also different from $L=0 \mathrm{and} 2$. The isoscalar $L=0 \mathrm{and} 2$ strengths in the giant resonance region yield (90\ifmmode\pm\else\textpm\fi{}20)% and (70\ifmmode\pm\else\textpm\fi{}20)% of the corresponding energy weighted sum rule limit. This is consistent with other hadron scattering results, with higher energy electron scattering, and with microscopic random phase approximation results. However, the strength for $L=2$ excitations is significantly larger than extracted from lower energy electron scattering. Fine structures observed are compared with high resolution (p,p\ensuremath{'}) and (e,e\ensuremath{'}) results. At scattering angles 5\ifmmode^\circ\else\textdegree\fi{}-8\ifmmode^\circ\else\textdegree\fi{} new structures have been observed at ${E}_{x}=12.5 \mathrm{and} 16.0$ MeV consistent with multipolarities $L=4 \mathrm{and} 6$. Together with the contribution of higher multipolarity extracted at lower excitation energies from the angular distributions of giant monopole and quadrupole excitations, this indicates rather broad distributions of $2\ensuremath{\hbar}\ensuremath{\omega}$ $L=4 \mathrm{and} 6$ excitations with centroid energies of 12.2 and 13.7 MeV and widths of 4.5 and 7.8 MeV, respectively. The extracted sum rule strengths for $L=4 \mathrm{and} 6$ are in the order of 30% in each case. In the region of the giant monopole resonance evidence for additional $L=2$ excitation was found (\ensuremath{\le}14% energy weighted sum rule strength). The fact that strong contributions of $Lg0$ are obtained solves the problem of a former too large monopole cross section in $\ensuremath{\alpha}$ scattering which was inconsistent with microscopic descriptions. A recently suggested "antiscaling" mode for the giant monopole resonance, in which the nuclear surface vibrates opposite in phase to the "scaling" mode, can be ruled out by our experimental data. The existence of two odd parity giant resonances at ${E}_{x}=18.7$ MeV ($L=3$) MeV ($L=1$) with widths of 5.0 and 5.9 MeV, respectively, are confirmed by our small angle scattering experiments. Our description of the dipole compressional mode is in excellent agreement with 200 MeV proton scattering data.NUCLEAR REACTIONS $^{208}\mathrm{Pb}(\ensuremath{\alpha}, {\ensuremath{\alpha}}^{\ensuremath{'}})$; ${E}_{\ensuremath{\alpha}}=172$ MeV. Small angle scattering, $\ensuremath{\theta}=1.5\ifmmode^\circ\else\textdegree\fi{}\ensuremath{-}8\ifmmode^\circ\else\textdegree\fi{}$; measured $\ensuremath{\sigma}(\ensuremath{\theta})$. Deduced excitation strength distributions for giant resonances of multipolarities $L=0\ensuremath{-}6$.

Electron capture and stripping cross sections of 3He ions in N2, Ne and Ar gas targets have been measured at 68, 99 and 130 MeV using a new method. While capture cross sections show discrepancies with available theories, the stripping cross sections can be explained fairly well by calculations of Gillespie (1978, 1980).

The nuclei 142 Nd and 142 Nd have been studied by means of high-resolution inelastic proton scattering at E p = 25 MeV. Angular distributions have been measured from θ lab = 20° to 50°. Transitions to 24 levels in 142 Nd and 39 levels in 143 Nd up to an excitation energy of 3.8 MeV were observed. Multipolarities L and transition strengths G L were determined using distorted-wave Born approximation analysis. Particle-core coupled configurations were identified in 143 Nd. In particular, the identification of all members of the octupole multiplet ( 3 − · νf 7 2 ) provides insights on the particle-vibration coupling in this region of nuclei. Coupling to other excitation modes is discussed, and comparison with unified model calculations is made.

A total of 13920 π−p → ppn events measured in a spark chamber experiment at 9.8 GeV incident π− momentum are compared with our data recently published on the same reaction at 18.8 GeV. The s-dependence of the total cross section, the shape of d2σdMdt, and the pp decay angular distributions at both energies suggest that the production process is dominated by one-pion exchange. This is supported by comparison with new π+p → pnp and pp → π+π− annihilation data. An interpretation of the angular distribution by partial waves is discussed, and results from a fit with a Breit-Wigner parametrization are presented. The cross section for the reaction π−p → ppn in the range Mpp ⩽ 2.7 GeV and |tnp| ⩽ 0.3 GeV2 has been determined to be σ = 6.5 ± 0.9 μb at 9.8 GeV.

A two-dimensional position sensitive detector with an area of 300 mm × 40 mm and a charged-particle spatial resolution of ΔX = ΔY ⩽ 0.5 mm is described. Some test results point out the detector properties. Results of the experiments 102 Ru(d,p) 103 Ru and 208 Pb(p,p′) 208 Pb done at 45 MeV incident particle energy using the magnetic spectrograph BIG KARL are shown with sections of the proton spectra.

Target thickness dependences of3He1+ yields from Al, Ni, Ag and Au targets were measured at 68, 99 and 130 MeV incident3He2+ energies, leading to electron stripping and capture cross sections. The results are compared with current theories.

We have measured 618 K+p → π+KS0p events at 12.7 GeV/c incident lab momentum, mass range 790 ⩽ mπ+Ks0 ⩽ 990 MeV and t range 0.01 ⩽ −t ⩽ 0.60 (GeV/c)2. The π+KS0 mass spectrum is dominated by the K∗+ (892) resonance and a Breit-Wigner fit yields a mass m = 893.5 ± 1.1 MeV and a width Γ = 33.2 ± 4.1 MeV which is much narrower than measured hitherto. The t distribution of K∗+ (892) events shows a dip in the forward direction and an exponential fall off thereafter, consistent with dominance of helicity flip amplitudes. The spin density matrix is almost saturated by ρ11 and ρ1−1 which are very close to their maximum allowed value of 1 2 throughout the measured t range except in the very forward direction where ρ00 and Re ρ10 deviate from zero. Natural parity exchanges, therefore, dominate with unnatural parity exchanges being restricted to a small region in the forward direction. A Regge pole analysis of the differential cross sections of the present measurement in conjunction with previously measured total cross sections supports the f-coupled-pomeron hypothesis.

Using a148Gd radioactive target and the (p,d), (d,t), and (3He,α) single neutron pick-up reactions we have measured the147Gd mass excess as — 75,366(4) keV, which differs by 139(24) keV from the adopted value of the 1983 mass table. From this result, and from recently reported first transfer-reaction mass determinations for145Eu and146Eu, we have recalculated the masses of nuclei above146Gd from a previous shell model analysis of high-spin states.

Results are presented of a study of ϱ-ω interference effects in high statistics, good resolution, π−p → π+π−n data obtained at 17.2 GeV using the CERN-Munich spectrometer. We investigate the t dependence of ϱ-ω interference in the various ππ production amplitudes. While effects are observed in all the P-wave production amplitudes, the most pronounced structure occurs in the natural parity exchange amplitude in the t interval 0.1 ⩽ −t ⩽ 0.4 GeV2. Under certain assumptions we determine the relative magnitudes and phases of the ϱ- and ω-production amplitudes as functions of t.

Angular distributions of the12C(d,7Li)7Be reaction to the ground and to the unresolved first excited states of7Li or7Be nuclei were measured in the entire angular region in the centre of mass system atElab=78.0 MeV. Both the one-step five-nucleon cluster transfer as well as two-step sequential transfers were considered in the theoretical analysis. The former mechanism was found to dominate, but the latter is also not negligible.

Angular distributions of the10B(α,7Li)7Be reaction were measured atElab = 91.8 MeV in the entire center of mass angular region. A DWBA analysis explains the reaction as triton and helion transfer in the forward and backward angular regions, respectively.

The high resolution magnetic spectrometer BIG KARL was used to investigate the low-lying states of 103Ru by 102Ru(d, p) and 104Ru(p,d) reactions at Ed = 45 MeV and Ep = 29 MeV. The resolution of ΔE E = (1.7–2.5) × 10 −4 was sufficient to separate most of the known states up to Ex = 1 MeV excitation energy. For these levels differential cross sections have been measured in the range of θlab = 4°–43°. A DWBA analysis has been employed in order to determine orbital angular momenta and obtain spectroscopic factors. These were used to make a number of tentative spin and parity assignments. In addition several weakly excited states in 103Ru could be identified and excitation energies have been determined to about ±2 keV.

Using the 209Bi(d, 3He)208Pb reaction at 45 MeV we have observed nearly the total strengths of the 1 h 9 2 particles, 3 s 1 2 , 2 d 3 2 , 1 h 11 2 or 2 d 5 2 hole multiplets with an energy resolution of 12 keV. We present the spectroscopic results and discuss some implications for recent studies of stretched configurations, magnetic dipole states and the proton particle- hole interaction.

We measure the reaction π−p→K−K0Sp at 17.2 GeV/c and observe some 1400 A−2→K−K0S decays, with no evidence for a double mass peak. The mass resolution is ±5.7 MeV. The A2 is produced in a nearly pure z.sfnc;j, m > = z.sfnc;2,1 > = z.sfnc;2,−1 > state in the Gottfried-Jackson system.

We have performed an energy-dependent and an energy-independent analysis of elastic ππ scattering, using data for the reaction π−p → π−π+n at 17.2 GeV/c. The ππ energy covers the range from 600 MeV to 1900 MeV. Apart from the well-known resonances ϱ, f and g, we find a strong S-wave in the π and also in the f-meson region. A P-wave resonance occurs in both analyses at ∼ 1600 MeV with a total width of 180 MeV and an elasticity of 0.25, which can be identified with the ϱ′ meson in its ππ decay mode. The zeros in the complex cos θ plane of the scattering amplitude are studied as a function of the energy. The position of the real parts of the zeros are in qualitative agreement with the prediction of the Veneziano model. Furthermore, we show that an analogous relation holds for the imaginary parts of the zero trajectories.

A sample of 10 350 π − p → p p n events with peripherally produced p p pairs has been observed in a spark chamber experiment. The differential cross-section dσ dt and the p p decay angular distribution suggest that one-pion exchange dominates the production process. The cross-section σ(π − π + → p p ) , obtained by a pole extrapolation, is compared with σ( p p →π + π − ) using detailed balance.

The I = 2 s-wave and d-wave phase shifts σs2and σd2 have been determined in the ππ mass region 0.5–1.5 GeV/c2 in four mass bins of width 0.25 GeV/c2, using a sample of 17 500 events from a wire chamber experiment. Two different methods were used, leading to consistent results. In the ϱ-mass region δs2 ≅ −15.5°, which corresponds to an elastic cross section of ≅ 7.5 mb. The values of δd2 are about a factor of ten smaller than the corresponding values of δs2.

We describe the construction and performance of wire spark chambers having an active area of 3.60×0.90 m 2 , a gap of 10 mm, and a wire spacing of 1 mm. Magnetostrictive read-out from both planes gives two coordinate values per chamber. Chambers of this type, together with smaller ones of similar construction, have been part of a magnet spectrometer which performed reliably between May 1970 and May 1971; during this time they were pulsed approximately 10 7 times.

The data from a spark chamber experiment are analysed for dipion masses below 1 GeV in terms of the s- and p-wave density matrix. The measured elements are given as functions of the dipion mass and of the momentum transfer. Bounds for the unmeasured matrix elements ρ 11 , Im ρ 10 , Im ρ 0S , Im ρ 1s are calculated using the positivity constraint. The intervals are very small and suggest that the production process has the property of equal phases of the amplitudes referring to the same ππ angular momentum. Next, the eigenvalues of the density matrix are determined within the positivity domain, and presented as functions of the dipion mass and the momentum transfer, showing that the rank is never greater than 3, and equal to 2 at the peak of the ρ meson, but could also be generally 2.

Differential cross sections for /sup 208/Pb(p,p') and /sup 208/Pb(d,d') excitation of the 1/sup +/ state at E/sub x/ = 5.846 MeV were measured at E/sub inc/ = 45 MeV. The fact that the measured strengths of both reactions are very similar supports the isoscalar nature of the 1/sup +/ state. The comparison of the experimental proton angular distribution to microscopic distorted-wave calculations using random phase approximation wave functions with and without tensor correlations suggests that the isoscalar tensor part of the (..pi..+rho)-exchange potential is too strong.

The three-, four-, and five-nucleon transfers were investigated by studying the $^{10}\mathrm{B}$(\ensuremath{\alpha},${\mathrm{}}^{7}$Li${)}^{7}$Be, $^{11}\mathrm{B}$${(}^{3}$He${,}^{7}$Li${)}^{7}$Be, and $^{12}\mathrm{C}$(d${,}^{7}$Li${)}^{7}$Be reactions, respectively. The measurements were performed in the entire center of mass angular region, at incident energies corresponding to 49.3 MeV in the center of mass system of the exit channel. A distorted-wave Born approximation analysis was performed including second-order transfer contributions for all investigated reactions.

The yield of /sup 3/He/sup 1 +/ ions produced by a /sup 3/He/sup 2 +/ beam in C, Al, Ni, Ag, and Au foils was measured at 68, 99, and 130 MeV in order to determine the electron-capture cross sections sigma/sub c/. Measurements were performed using targets thicker than 60 ..mu..g/cm/sup 2/, where charge equilibrium was found. The results are compared with electron-stripping and -capture theories, which are found to explain fairly well the yield of /sup 3/He/sup 1 +/.

In this contribution we report on inelastic hadron scattering experiments to 1+ spin flip states in 48Ca, 58Ni and 208Pb using the high resolution spectrometer BIG KARL at the Julich cyclotron facility. Experimental and theoretical investigations of spin flip excitations in nuclei are stimulated by the perspective to obtain information on the nature of the spin \(\left( {\vec \sigma \vec \sigma } \right)\) and spin-isospin \(\left( {\vec \sigma \,\,\vec \sigma {\kern 1pt} \vec \tau \,\,\vec \tau } \right)\) parts of the residual particle-hole (ph) interaction which in the Landau-Migdal parametrisation1,2, can be written as: $${F_{ph}}\left( {{{\vec r}_1} - {{\vec r}_2}} \right) = {C_o}\left( {{g_o}{{\vec \sigma }_1}{{\vec \sigma }_2} + {g_o}{{\vec \sigma }_1}{{\vec \sigma }_2}{{\vec \tau }_1}{{\vec \tau }_2}} \right)\delta \left( {{{\vec r}_1} - {{\vec r}_2}} \right);$$ (1) The magnitude of the force strength parameter go’ which describes the short range spin-isospin correlations is intimately related to the experimentally observed quenching of the total Ml- and Gamow-Teller (GT) strength. For this reason spin excitations in nuclei are presently investigated experimentally by many groups using preferably highly selective reactions like (p,n) charge exchange3, inelastic electron scattering4,5 at backward angles and nuclear resonance fluorescence with polarized photons (γ,γ’)6.

Results of an energy‐dependent phase‐shift analysis for ππ scattering between 900 and 1120 MeV mass are presented using data of the reactions π±p ⇒ π±π+n and π−p ⇒ K+K−n. The I = 0 S‐wave becomes highly inelastic at KK threshold and accounts for the structure in the ππ system. A zero effective range approximation for the S‐ wave leads to a pole of the S‐matrix which is located on the second Riemann sheet at (1012 ± 6) − i(16 ± 5) MeV.

Wa have performed an energy‐dependent and an energy‐independent analysis of elastic ππ scattering, using data for the reaction π−p ⇒ π−π+n at 17.2 GeV/c. The ππ energy covers the range from 600 MeV to 1900 MeV. Apart from the well‐known resonances ρ, f and g, we find a strong S‐wave in the ρ and also in the f‐meson region. A P‐wave resonance occurs in both analyses at ∼ 1600 MeV with a total width of 180 MeV and an elasticity of 0.25, which can be identified with the ρ′ meson in its ππ decay mode. The zeros in the complex cos Θ plane of the scattering amplitude are studied as a function of the energy. The position of the real parts of the zeros are in qualitative agreement with the prediction of the Veneziano model. Furthermore, we show that an analogous relation holds also for the imaginary parts of the zero trajectories.

The ππ phase‐shifts have been determined by a Chew‐Low extrapolation in the ππ mass region from 500 to 1500 MeV using data of a spark chamber experiment on π−p ⇒ π−π+n at 17.2 GeV/c, which yielded 318,000 events. We find an I = 0 s‐wave phase shift which increases slowly, passing through 90° near 900 MeV, and then rises very rapidly. The old “up” solution is eliminated on the basis of fits in the mass region from 900–1000 MeV.

We perform an energy independent ππ phase shift analysis in the energy range 440

The I = 2 s‐ and d‐wave ππ phase shifts δs2 and δd2 have been determined in the ππ mass region from 500–1500 MeV, using a sample of 17,500 events π+p ⇒ π+π+ from a spark chamber experiment. For this purpose the moments of the ππ angular distribution in the s‐channel helicity frame have veen written as bilinear expressions of OPE amplitudes modified by absorption and have been fitted to the measured values of the moments in four mass bins of width 0.25 GeV/c2. The value of δs2 in the ρ‐mass region (δs2 ≃ −15.5°) corresponds to an elastic cross‐section of ≃ 7.5mb.The values of δd2 are about a factor of 10 smaller than the corresponding values of δs2 for the whole mass region considered.

A high resolution experiment, using the BIG KARL spectrometer has been made to identify the levels of 141 Pr excited in the 144 Nd(p,α) reaction at 25 MeV. It has been found that only levels with a dominant single proton component are populated with appreciable intensity.

A spherical harmonic moment analysis of 220 000 events of the reaction π − p → π − π + n at 17.2 GeV/ c determines the spin-parity of the g-meson to be 3 − .