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Total and differential cross sections for the reactions p + d → 3He + m 0 with m=π, η and p + d → 3H+π+ were measured with the GEM detector at COSY for beam momenta between threshold and the maximum of the corresponding baryon resonance. For both reactions a strong forward-backward asymmetry was found. The data were compared with model calculations. The aspect of isospin symmetry breaking is studied.

The production of neutral and charged pions as well as eta mesons is studied in the Delta and N* resonance region, respectively. Heavy A=3 recoils were measured with the GEM detector. The differential cross sections covering the full angular range are compared with model calculations., Comment: 4 pages, latex, 4 figures, talk presented at the XVIIth European Conference on Few-Body Problems in Physics, Evora, Portugal, September 2000; to be published in Nucl. Phys. A

We present a method to determine precisely the absolute momentum of the external proton beam from the Julich Cooler Synchrotron COSY near 1930 MeV /c . In the pp → d π + reaction at 1930.477 MeV /c incident beam momentum, the forward going pions ( θ c.m. =0° ) and the backward going deuterons ( θ c.m. =180° ) have the same laboratory momentum. Such coincident pion–deuteron events are detected in the focal plane of the magnetic spectrometer BIG KARL located at θ lab =0° . Using the nearly linear dependence of the difference between the measured pion and deuteron momenta as a function of the proton beam momentum, the absolute momentum of the external proton beam from COSY near 1930 MeV /c was determined with a precision of 5.2×10 −5 .

A stack of annular detectors made of high-purity germanium was developed. The detectors are position sensitive with radial structures. The first one (“Quirl”) is double-sided position sensitive defining 40 000 pixels, the following three (E1, E2 and E3) have 32 wedges each. The Quirl acts as tracker while the other three act as calorimeter. The stack was successfully operated in meson production reactions close to threshold.

Experimental results on X-rays in antiprotonic Te, Sm, and Pt isotopes are presented. Attenuation of some lines due to the dynamic E2 mixing with nuclear rotational excitations was observed. The results are analyzed in terms of the p optical potential. Some effects of deformation are discussed. Previous findings such as a strong ls potential and the density dependence of the optical potential are confirmed.

Energy spectra of protons, deuterons and tritons from stopped-antiproton annihilation in Li, Si, Ca, Ni, Ge, Mo, Ho, Yb, Pb and Th have been measured with a Ge detector telescope. The shapes of these and of previously obtained spectra and the corresponding yields were analysed and compared with statistical calculations including intranuclear cascade, coalescence, pre-equilibrium processes, evaporation, multifragmentation and Fermi break-up. The relative importance and the A -dependence of the various processes are elucidated.

The distribution of nuclei resulting from the annihilation of stopped antiprotons on238U has been studied by an off-line measurement of the residual radioactivity. It was found that the probability of fission exceeds 84% (68% c.l.). The charge and mass distributions of the fission products can be separated into two parts, a more frequent symmetric component originating from high energy fission (excitation energy between 100 MeV and 1 GeV) and an asymmetric component from low energy fission (excitation energy less than 40 MeV).

Energy spectra of protons, deuterons and tritons from the annihilation of antiprotons stopped in 12C, 40Ca, 63Cu, 92,98Mo and 238U have been measured with a Ge-detector telescope. Parameters related to the shape of the spectra were calculated and their dependence on target and ejectile mass number was determined. Yields per p of directly emitted protons, deuterons and tritons and of evaporated protons were estimated.

We propose to study pionic atoms in low‐lying states. The pions will be produced with the help of recoil free kinematics at small energies in the laboratory. A dedicated detector will be applied allowing the measurements of the width as well as the energy shift of these states.

Yield curves were measured for formation of 7 Be and of residual nuclei formed by α-particle and nucleon emission following the reactions of 16 to 75 MeV 14 N and 16 O ions with thick, natural C, Mg, Al and Si targets. The results are discussed in terms of statistical model calculations. Yield curves calculated with computer codes based on the statistical model are compared with the experimental results.

The strong-interaction effects in antiprotonic 6Li, 7Li, 14N, 19F, and 23Na atoms were measured at the CERN antiproton facility, LEAR. For the 2p level we determined the shifts to be −215 ± 25 eV (6Li) and −265 ± 20 eV (7Li) and the widths to be 660 ± 170 eV (6Li) and 690 ± 170eV (7Li). For the 3d level we obtained for the shifts −40 ± 30 eV (14N), −t-440 ± 70 eV (19F), and −2.1 ± 0.3 keV (23Na), and for the widths 0.135 ± 0.016 (6Li), 0.129 ± 0.013 eV (7Li), 218 ± 75 eV (14N), 1365 ± 150 eV (19F), and 2.9 ± 1.1 keV (23Na).

The application of a thin film scintillator detector (TFD) for the identification of heavy ion products from the well-known reactions 12C+16O, 12C+14N, 12C+12C and 12C+7Li has been made. The TFD was used to measure values proportional to specific luminescence and a solid state detector was used for incident and residual particle energy measurements. In parallel experiments the TFD was exposed to a range of monoenergetic ion beams of 16O, 14N, 12C and 7Li, as well as to alpha particles from a 228Th decay source, in order to establish calibration curves. These spectra were collated with as to alpha particles from a 228Th decay source, in order to establish calibration curves. These spectra were collated with two-parameter plots of coincident signals from the solid state and scintillator detectors for each reaction. Trends in specific luminescence as a function of ion energy-loss and luminescence efficiency vs. ion energy are also presented. Calculations based on two different models of specific luminescence production are shown to agree with the general behavior exhibited by the five ions.

The luminescence response of a thin-film detector to fragments from the fission of 232 Th, 235 U, and 238 U induced by 10–18 MeV protons was determined. Measurements were made in coincidence with signals from a surface-barrier solid-state detector, and the detector responses were displayed for each energy as two-parameter plots. Detector responses to 252 Cf spontaneous-fission fragments were determined for comparison. Results are consistent with previous work at comparable energies. The possible significance of a previously observed change in symmetric-to-asymmetric fission ratio near 15 MeV bombarding energy, and the applicability of thin-film detectors to identification of unknown fissioning nuclides are discussed.

X-ray yields of the muonic helium (2-1) transition from $\ensuremath{\mu}$-catalyzed fusion have been measured for the first time in various mixtures of hydrogen isotopes. They were determined to be 0.032(4), 0.016(2), and 0.0019(5) for $\mathrm{pd}$, $\mathrm{dd}$, and $\mathrm{dt}$ fusion, respectively.

Observed γ-ray transitions from bound and nearly bound levels of all known nuclides in the mass range A = 21 to A = 32 are tabulated for use in reaction (on-line, in-beam) γ-ray spectroscopy. The tables present energies, spins, and parities of the nuclear levels, the transition (photopeak) energy corrected for recoil, the corresponding Compton edge and escape peaks, as well as competing decays, mean lives, and branching ratios when known. The information is arranged in order of both increasing γ-ray energy and nuclide mass number. The literature cutoff date is Aug. 15, 1974.

Spectra of hydrogen and helium ions emitted after stopped antiproton annihilation in nuclei have been measured with a Si-detector telescope. Targets of 12C, 40Ca, 63Cu, 92Mo, 98Mo and 238U were used. The 3He and 4He energy spectra can be fitted with the exponential function e−E/T. The parameter T is essentially independent of the target mass number A. A simple pickup model reproduces the 4He/3He ratios as a function of Z and N (target proton and neutron number). The proton spectra from the 238U target indicate that some protons are also emitted by the fission fragments.

Activation cross sections for the reactions 19F(π−, π−n) 18F and 31P(π−, π−n) 30P were measured at pion energies from 140 to 240 MeV and found to reach maxima of 39 ± 5 mb and 60 ± 11 mb, respectively, near 180 MeV. The results are compared with calculated cross sections and with the results of other measurements.

Threshold measurements of the beta decay activity from the residual nucleus in the reaction K 39 ( α , n)Sc 42 yield a ground state Q value of −7.455±0.030 MeV and energy levels of Sc 42 at 0.526±0.020, 0.600±0.030, 1.42±0.030, 2.22±0.030, 2.96±0.030 and 3.57±0.040 MeV. Position end-point energies calculated from threshold values are 5.525±0.030 MeV for the superallowed decay of the Sc 42 ground level to the Ca 42 ground level and 2.820± 0.030 MeV for the allowed decay of Sc 42m to the 3.191 MeV level of Ca 42 . The total cross section is 2.2±0.2 mb for the K 39 ( α , n)Sc 42 reaction and 6.6±0.6 mb for the K 39 ( α , n)Sc 42 m reaction at alpha-particle energies 1.45 MeV above the respective thresholds. The half-life is 0.65±0.01 sec for the superallowed decay and 60.6±0.4 sec for the allowed decay. The experimental levels compare reasonably well with those predicted by a jj coupling shell model. The energy difference between the isometric levels of Sc 42 is in accord with a systematic tendency of the energy difference between the lowest T = 0 and T = 1 levels in odd nuclei with N = Z .

The activation cross section for 27 Al (π + ,π 0 ) 27 Si at E π = 99 ± 9 MeV was determined to be 5.1 ± 2.2 mb by counting the residual β+ activity of 27Si. This result is compared with other pion-nucleus cross sections. A value for the elementary pion-nucleon cross section inside the nucleus is derived from this result and compared with an estimate from a phenomenological expression.

The mass and beta-decay half-life for 43 Ti has been measured using the 40 Ca(α, n) 43 Ti reaction. The mass excess ( 12 C scale) was determined to be −29325±15 keV from a value of 12290±10 keV for the reaction threshold. The corresponding beta end-point energy was calculated to be 5.83±0.02 MeV. The half-life of 43 Ti was measured to be 0.49±0.01 sec. The corresponding log ft value is 3.47±0.03.

The reactions 46Ti(p, α)43Sc, 48Ti(p, α)45Sc and 50Ti(p, α)47Sc were initiated in isotopically enriched and natural targets with protons of 9, 9.5 and 10 MeV from a tandem accelerator. The reaction products were analysed and detected at 45°, 60° and 125° with a magnetic spectrograph. The Q values, excitation energies and absolute cross sections were determined. The energy level spectra of 43Sc, 45Sc and 47Sc emerging from this and other recent work are used to determine the applicability of several nuclear models to these nuclei.

A mechanical beam stop for work with short-lived beta and gamma activities is described. It opens or closes within 50 msec, is simple to build and use, and performs reliably over many successive opening and closing cycles. Also described are a variable-width double-slit system for beam collimation and a beam viewer.

Antiprotonic x ray spectra of146Nd and148Nd have been measured with Ge detectors. Different attenuations of the two fine structure components of the antiprotonic x ray group (n=9 → n=8) due to the E2 nuclear resonance effect were observed in148Nd. Experiment and present theory disagree. We propose to supplement the ¯p-nucleus potential by a spin-orbit term.

A high-precision measurement of the finestructure splitting in the circular 11→10 X-ray transition of\(\bar p^{208} Pb\) was performed. The experimental value of 1199(5) eV is in agreement with QED calculations. From that value the magnetic moment of the antiproton was deduced to be −2.8005(90)μnucl. With this result the uncertainty of the previous world average value was reduced by a factor of ≈2. A comparison with the corresponding quantity of the proton now yields:\({{\left( {\mu _p - \left| {\left\langle {\mu _{\bar p} } \right\rangle } \right|} \right)} \mathord{\left/ {\vphantom {{\left( {\mu _p - \left| {\left\langle {\mu _{\bar p} } \right\rangle } \right|} \right)} {\mu _p }}} \right. \kern-\nulldelimiterspace} {\mu _p }} = \left( { - 2.4 \pm 2.9} \right) \times 10^{ - 3} \).

The strong ¯p-nucleus spin-orbit interaction was investigated in a measurement of the strong-interaction effects of the 9→8 transition in ¯p174Yb at the Low-Energy Antiproton Ring (LEAR) at CERN. This measurement was part of an experimental programme where, for the first time, the fine-structure components of the last observable X-ray transition in a ¯p atom, which carries information on the strong ¯p-nucleus interaction, were resolved and studied individually. The observed splitting ΔEexp=2408±26 eV consists of the electromagnetic fine-structure splitting ΔEFS=2350 eV and an additional splitting Δɛ=58±26 eV. In addition, one finds a significant difference in the level widths of Δ=195±59 eV with the larger value⇊=1216±41 eV for the lower fine-structure level. This experiment follows an earlier measurement on ¯p138Ba, where the transition 8→7 is influenced by the strong interaction. In this case, however, the fine-structure components could not be resolved. The results for174Yb may be attributed to a spin-orbit (LS) term in the complex strong-interaction potential.

Observed and possible {gamma}-ray transitions from bound and nearly bound levels of all known nuclides up to A = 20 are tabulated for use in prompt (on-line) {gamma}-ray spectroscopy. The tables include energies, spins, and parities of the nuclear levels, the transition (photo peak) energy corrected for recoil, the corresponding Compton edge and escape peaks, as well as competing decays, mean life, and branching ratios when known. The information is arranged in order of both increasing {gamma}-ray energy and nuclide mass number. 2 tabs. (auth)

The ground-state β + decay of 42 Ti has been investigated through tthe reaction 40 Ca( 3 He, n). The half-life was found to be 173± 14 ms. The branching ratios to the 1 + level at 615 keV and to the 0 + ground state in 42 Sc are 56± 14% and 44± 14%, respectively. The calculated log ft values are 3.11 ± 0.14 for the 0 + → 1 + transition and 3.43 ± 0.12 for the 0 + → 0 + transition.

Yield curves for formation of 7Be and other radio-nuclides from bombardment of C, Al and Si targets with 16–58 MeV 14N and 16O ions were measured. The 7Be yields disagree by several orders of magnitude with Hauser-Feshbach and transition-state predictions. The other yields are in order-of-magnitude agreement with nucleon and/or α-particle evapolation calculations.