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International audience; Several factors can contribute to the difficulty of aligning the sensors of tracking detectors, including a large number of modules, multiple types of detector technologies, and non-linear strip patterns on the sensors. The latter two of these three factors apply to the CLAS12 CVT, which is a hybrid detector consisting of planar silicon sensors with non-parallel strips, and cylindrical micromegas sensors with longitudinal and arc-shaped strips located within a 5 T superconducting solenoid. To align this detector, we used the Kalman Alignment Algorithm, which accounts for correlations between the alignment parameters without requiring the time-consuming inversion of large matrices. This is the first time that this algorithm has been adapted for use with hybrid technologies, non-parallel strips, and curved sensors. We present the results for the first alignment of the CLAS12 CVT using straight tracks from cosmic rays and from a target with the magnetic field turned off. After running this procedure, we achieved alignment at the level of l. 967 10μm, and the widths of the residual spectra were greatly reduced. These results attest to the flexibility of this algorithm and its applicability to future use in the CLAS12 CVT and other hybrid or curved trackers, such as those proposed for the future Electron-Ion Collider.

We present the first measurement of di-hadron angular correlations in electron-nucleus scattering. The data were taken with the CLAS detector and a 5.0 GeV electron beam incident on deuterium, carbon, iron, and lead targets. Relative to deuterium, the nuclear yields of charged-pion pairs show a strong suppression for azimuthally opposite pairs, no suppression for azimuthally nearby pairs, and an enhancement of pairs with large invariant mass. These effects grow with increased nuclear size. The data are qualitatively described by the GiBUU model, which suggests that hadrons form near the nuclear surface and undergo multiple-scattering in nuclei. These results show that angular correlation studies can open a new way to elucidate how hadrons form and interact inside nuclei, Comment: 6 pages, 4 figures

High light yield scintillation materials on the base of lanthanide ions were demonstrated to be a multipurpose scintillation materials. They are widely used to detect γ –quanta and now become prospective to detect neutrons as well. Neutrons were detected through several distinct low energy γ –quanta peaks, generated by lanthanide nuclei in the materials under neutrons. Among three crystalline scintillators , namely lutetium oxy-orthosilicate, lanthanum bromide and gadolinium–aluminum–gallium garnet, the Gd 3Al2Ga3O12 :Ce (GAGG) scintillator showed the best performance and sensitivity due to the low internal background radioactivity and good cross section of neutron capture by natural mixture of the matrix host-creating Gd ions. The material fits the requirements for neutron detector properties — high Gd content and high scintillation light yield, stopping power and reasonable energy resolution for γ -quanta. These findings create prospects to construct compact multipurpose detectors for space and other application.

A measurement of the double-polarization observable E for the reaction $$\gamma p\rightarrow \pi ^0 p$$ γ p → π 0 p is reported. The data were taken with the CBELSA/TAPS experiment at the ELSA facility in Bonn using the Bonn frozen-spin butanol (C$$_4$$ 4 H$$_9$$ 9 OH) target, which provided longitudinally-polarized protons. Circularly-polarized photons were produced via bremsstrahlung of longitudinally-polarized electrons. The data cover the photon energy range from $$E_\gamma =600$$ E γ = 600 to 2310 MeV and nearly the complete angular range. The results are compared to and have been included in recent partial wave analyses.

Data on the beam asymmetry Σ in the photoproduction of η mesons off protons are reported for tagged photon energies from 1130 to 1790 MeV (mass range from W=1748 MeV to W=2045 MeV). The data cover the full solid angle that allows for a precise moment analysis. For the first time, a strong cusp effect in a polarization observable has been observed that is an effect of a branch-point singularity at the pη^{'} threshold [E_{γ}=1447 MeV (W=1896 MeV)]. The latest BnGa partial wave analysis includes the new beam asymmetry data and yields a strong indication for the N(1895)1/2^{-} nucleon resonance, demonstrating the importance of including all singularities for a correct determination of partial waves and resonance parameters.

A measurement of the double-polarization observable E for the reaction \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\gamma p\rightarrow \pi ^0 p$$\end{document}γp→π0p is reported. The data were taken with the CBELSA/TAPS experiment at the ELSA facility in Bonn using the Bonn frozen-spin butanol (C\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$_4$$\end{document}4H\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$_9$$\end{document}9OH) target, which provided longitudinally-polarized protons. Circularly-polarized photons were produced via bremsstrahlung of longitudinally-polarized electrons. The data cover the photon energy range from \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$E_\gamma =600$$\end{document}Eγ=600 to 2310 MeV and nearly the complete angular range. The results are compared to and have been included in recent partial wave analyses.

The Barrel-Time-of-Flight detector is one of the outer layers in the multi-layer design of the P anda target spectrometer, covering a polar angle region of 22 ° θ l a b 150 ° . P anda , which is being built at the FAIR facility, will use cooled antiprotons on a Hydrogen or nuclei target, to study a variety of topics in hadron physics. The detector is a scintillating tile hodoscope with an SiPM readout. A single unit consists of a 90 × 30 × 5 mm 3 fast plastic scintillator tile and 3 × 3 mm 2 SiPM photosensors on both ends. Four SiPMs are connected in series to overcome the limited sensor size of a single SiPM sensor and to improve the time resolution drastically (100 ps to 50 ps). While the P anda experiment is equipped with DIRC detectors for PID of faster particles, the Barrel TOF complements the setup by providing additional PID information with a π /K separation of 4 sigma up to the Cherenkov threshold.

The barrel-Time-of-Flight detector is one of the outer layers of the multi-layer design of the PANDA target spectrometer. PANDA, which is being built at the FAIR facility, will use cooled antiprotons on a fixed Hydrogen or nuclei target, to study broad topics in hadron physics. The detector is designed to achieve a time resolution below 100 ps and provides the interaction times of events as well as the particle ID. The B-TOF is designed with a minimal material budget in mind mainly consisting of 5 mm thin plastic scintillator tiles read out by a serial connection of 4 SiPMs. The signal transmission is embedded in large 16 layer PCB in micro strip lines. We will first review the detector concept which is described in the TDR then some more recent developments, with a study of different PCB layouts for signal transmission, the readout with the TOFPET2 ASIC and its performance and presenting the results of a study on the influence of the scintillator thickness on the time resolution.

The first measurements of the beam-target-helicity-asymmetries $E$ and $G$ in the photoproduction of $\omega$-mesons off protons at the CBELSA/TAPS experiment are reported. $E$ ($G$) was measured using circularly (linearly) polarised photons and a longitudinally polarised target. $E$ was measured over the photon energy range from close to threshold ($E_\gamma = 1108$~MeV) to $E_\gamma = 2300$~MeV and $G$ at a single energy interval of $1108 < E_\gamma, Comment: 6 pages, 6 figures

Data on the polarization observables T, P, and H for the reaction gamma p -> p pi(0) are reported. Compared to earlier data from other experiments, our data are more precise and extend the covered range in energy and angle substantially. The results were extracted from azimuthal asymmetries measured using a transversely polarized target and linearly polarized photons. The data were taken at the Bonn electron stretcher accelerator ELSA with the CBELSA/TAPS detector. Within the Bonn-Gatchina partial wave analysis, the new polarization data lead to a significant narrowing of the error band for the multipoles for neutral-pion photoproduction. (C) 2015 The Authors. Published by Elsevier B.V.

The electromagnetic calorimeter (EMC) of the PANDA detector at the future FAIR facility is composed of two endcaps and a barrel covering the major part of the solid angle consisting of more than 11.300 tapered PbWO4 crystals. The individual scintillator modules are readout via two large area avalanche photo diodes. The signal processing is performed with a custom made ASIC-preamplifier providing a large dynamic range, low noise and reduced power consumption since the calorimeter will be operated at a temperature of −25°C. The first major assembly stage outlined in this paper is going to be conducted beginning in mid 2016 by assembling one single barrel slice segment. The construction of this segment comprises a full length slice beam holding a total of 18 module blocks, each one being a matrix of 4×10 crystals, in place. The assembly procedure of single detector modules, 40-crystal module blocks and the overall slice segment, respectively will be discussed and important findings during the procedure mentioned. In order to lay out and optimize the assembly procedure, the results and experiences gained with an earlier 80-crystal fully functional prototype detector were accounted for, which are reviewed in this contribution. Test results of single components and fully assembled detector modules will be discussed and compared with earlier prototype in-beam and lab tests as well as with the envisaged PANDA requirements.

P ¯ ANDA is a dedicated antiproton experiment at the future FAIR facility at GSI benefiting from antiproton beams with unprecedented intensity and quality. High-precision spectroscopy in the charm quark sector is part of the core physics program. The micro-vertex-detector (MVD) is the innermost part of the tracking system. It plays a key role for the vertex reconstruction and momentum resolution of charged particles. This article contains a short description of the P ¯ ANDA experiment and the MVD design. Detector simulations for the MVD are based on a detailed model allowing a realistic description. Presented results of physics simulations refer to selected reaction channels with charged particles in the final state. Besides the reconstruction of D -mesons a study of the X (3872) is included.

A systematic study of the production of omega-mesons in proton-proton-collisions was carried out in a kinematically complete experiment at three excess energies(epsilon= 92, 128, 173MeV). Both protons were detected using the large-acceptance COSY-TOF spectrometer at an external beam line at the Cooler Synchrotron COSY at Forschungszentrum J\"ulich. The total cross section, angular distributions of both omega-mesons and protons were measured and presented in various reference frames such as the overall CMS, helicity and Jackson frame. In addition, the orientation of the omega-spin and invariant mass spectra were determined. We observe omega-production to take place dominantly in Ss and Sp final states at epsilon = 92, 128 MeV and, additionally, in Sd at epsilon= 173 MeV. No obvious indication of resonant omega-production via N^*-resonances was found, as proton angular distributions are almost isotropic and invariant mass spectra are compatible with phase space distributions. A dominant role of ^3P_1 and ^1S_0 initial partial waves for omega-production was concluded from the orientation of the decay plane of the omega-meson. Although the Jackson angle distributions in the omega-p-Jackson frame are anisotropic we argue that this is not an indication of a resonance but rather a kinematical effect reflecting the anisotropy of the omega angular distribution. The helicity angle distribution in the omega-p-helicity frame shows an anisotropy which probably reflects effects of the omega angular momenta in the final state; this observable may be, in addition to the orientation of the omega decay plane, the most sensitive one to judge the validity of theoretical descriptions of the production process.

The quasifree reaction $np\to pp\pim$ was studied in a kinematically complete experiment by bombarding a liquid hydrogen target with a deuteron beam of momentum 1.85 GeV/c and analyzing the data along the lines of the spectator model. In addition to the three charged ejectiles the spectator proton was also detected in the large-acceptance time-of-flight spectrometer COSY-TOF. It was identified by its momentum and flight direction thus yielding access to the Fermi motion of the bound neutron and to the effective neutron 4-momentum vector $\mathbb{P}_n$ which differed from event to event. A range of almost 90 MeV excess energy above threshold was covered. Energy dependent angular distributions, invariant mass spectra as well as fully covered Dalitz plots were deduced. Sizeable $pp$ FSI effects were found as were contributions of $p$ and $d$ partial waves. The behavior of the elementary cross section $\sigma_{01}$ close to threshold is discussed in view of new cross section data. In comparison with existing literature data the results provide a sensitive test of the spectator model.

The p p → p K 0 Σ + reaction was investigated with the TOF spectrometer at COSY at 3.059 GeV / c incident beam momentum. The main objective was to clarify whether or not a narrow exotic S = + 1 resonance, the Θ + pentaquark, is populated at 1.53 GeV / c 2 in the p K 0 subsystem with a data sample of much higher statistical significance compared to the previously reported data in this channel. An analysis of these data does not confirm the existence of the Θ + pentaquark. This is expressed as an upper limit for the cross section σ ( p p → Σ + Θ + ) 0.15 μb at the 95% confidence level.

The physics program of PANDA covers a wide range of topics that address central issues of QCD. The PANDA detector will make use of the antiprotons produced in the FAIR complex and stored in the high-energy synchrotron HESR for the study of strong interactions in collisions with protons and heavy targets. Central to the program and defining the guidelines for the detector development are the spectroscopy of charmonium states and open charm with unprecedented quality, the search for exotic objects such as glueballs and hybrids, investigation of the modification of meson properties in medium, and copious production of hypernuclei for high-resolution spectroscopy. Technical developments for the various detector components are ongoing. The detector properties required in order to cover the broad physics program pose challenges which need state-of-the-art technology and customized solutions.

The reaction \(dp \ensuremath \rightarrow ppp \pi^-\) has been studied in a kinematically complete experiment at a single beam momentum \(\ensuremath p_{d}=1.85\)GeV/c (T = 759MeV). All four ejectiles have been detected in the large-acceptance time-of-flight spectrometer COSY-TOF. We analyzed the data along the lines of the spectator model as a means to isolate the quasi-free \(\ensuremath np\rightarrow pp\pi^-\) reaction. The spectator proton was identified by its momentum and flight direction thus yielding access to the associated Fermi motion of the bound neutron. A comparison is carried out with Monte Carlo simulations based on two different parameterizations of the deuteron wave function. Up to a Fermi momentum of roughly 150MeV/c no significant deviations between experimental and simulated data of various observables were found from which we conclude that the deuteron can indeed be taken as a valid substitute for the neutron.

Hyperon production in the threshold region was studied in the reaction pp → K + Λ p using the time-of-flight spectrometer COSY-TOF. Exclusive data, covering the full phase-space, were taken at three different beam momenta p beam = 2.59 , 2.68 and 2.85 GeV/ c (corresponding to excess energies of ɛ = 85 , 115 and 171 MeV). Total cross-sections were deduced to be 7.4 ± 0.5 μb , 8.6 ± 0.6 μb and 16.5 ± 0.4 μb , respectively. Differential observables including Dalitz plots were obtained. From the investigation of the Dalitz plot at p beam = 2.85 GeV / c a dominant contribution of the N ∗ ( 1650 ) -resonance to the reaction mechanism was found. In addition the pΛ -final-state interaction turned out to have a significant influence on the Dalitz plot distribution even 171 MeV above threshold.

The production of vector mesons in collisions between nucleons is studied in order to address a variety of issues concerning nucleon-nucleon interaction, reaction mechanism and properties of baryons. These studies are summarized with emphasis on the most recent experiments at the Time-of-Flight spectrometer TOF and results obtained at the COoler SYnchrotron COSY in Jülich. While currently the open questions regarding the so-called OZI violation, its relation to the meson exchange picture and the relative importance of contributions to the production mechanism from various channels within this formalism are still unresolved, the present-day experiments hold the potential to clarify the situation greatly. Possible extensions of the experimental program on vector mesons using 4π detection techniques for charged as well as neutral particles, in particular π0, are discussed.

The future PANDA-Experiment at the FAIR accelerator facility in Darmstadt/Germany utilizes an antiproton beam with momenta of 1.5 – 15 GeV/c incident on a hydrogen or heavy element fixed target. It addresses open questions concerning the strong interaction with one focus on high precision charmonium spectroscopy. The spatial and timing resolution in detecting fast-decaying particles e.g. in open-charm channels is crucial and requires the application of thin solid state detectors coupled with a fast untriggered readout electronics. The contribution will focus on the silicon microstrip tracker of the innermost subdetector, the Micro Vertex Detector (MVD), which is composed of double-sided silicon strip detectors (DSSDs). These are connected to ultrathin flex modules carrying novel fast self-triggering front-end ASICs named PASTA. The construction of the DSSD modules, the carrier PCB and the architecture of the PASTA chip will be discussed as well as methods to qualify the sensors. An overview of the prototypes developed and tested up to now is given together with the future steps to be taken in order to arrive at the mass production of the full-scale modules.

New data on the polarization observables T, P, and H for the reaction γp→pπ0 are reported. The results are extracted from azimuthal asymmetries when a transversely polarized butanol target and a linearly polarized photon beam are used. The data were taken at the Bonn electron stretcher accelerator ELSA using the CBELSA/TAPS detector. These and earlier data are used to perform a truncated energy-independent partial wave analysis in sliced-energy bins. This energy-independent analysis is compared to the results from energy-dependent partial wave analyses.

New data on the polarization observables T, P, and H for the reaction γp→pπ(0) are reported. The results are extracted from azimuthal asymmetries when a transversely polarized butanol target and a linearly polarized photon beam are used. The data were taken at the Bonn electron stretcher accelerator ELSA using the CBELSA/TAPS detector. These and earlier data are used to perform a truncated energy-independent partial wave analysis in sliced-energy bins. This energy-independent analysis is compared to the results from energy-dependent partial wave analyses.

The first measurement of the helicity dependence of the photoproduction cross section of single neutral pions off protons is reported for photon energies from 600 to 2300 MeV, covering nearly the full solid angle. The data are compared to predictions from the SAID, MAID, and BnGa partial wave analyses. Strikingly large differences between data and predictions are observed, which are traced to differences in the helicity amplitudes of well-known and established resonances. Precise values for the helicity amplitudes of several resonances are reported.

The cross section for the production of $\omega$ mesons in proton-proton collisions has been measured in a previously unexplored region of incident energies. Cross sections were extracted at 92 MeV and 173 MeV excess energy, respectively. The angular distribution of the $\omega$ at $\epsilon$=173 MeV is strongly anisotropic, demonstrating the importance of partial waves beyond pure s-wave production at this energy., Comment: 12 pages, 4 figures submitted to Physics Letters B v2: figure 1 added, discussion detailing the data analysis, figure 3 (fig. 2 in v1) modified in line styles and systematic errors displayed on data

A pronounced fine structure (FS) in the form of distinct peaks was observed in neutron gated mass spectra from the decay of the 278110 composite system produced in the reaction 238U + 40Ar (243 MeV) at an initial excitation energy E * > 70 MeV. The FS peaks are located in the vicinity of mass numbers 70-80, 100, and 130, which correspond to those of magic nuclei (clusters). In the data there is also evidence for a new type of decay -- collinear cluster tripartition of an excited nucleus.

A plastic scintillator array of 3.4 m 2 total area for the detection of neutrons in medium-energy nucleon–nucleon reactions was constructed and built. Calibration procedures for the detector were developed which allow the monitoring of gain shifts by means of muons from the cosmic radiation. Experiments were performed in order to calibrate the efficiency simulations and study the performance of the detector using the d+t→α+n reaction at 14.7 MeV neutron energy and proton-induced deuteron breakup at 300 MeV .

Small liquid hydrogen/deuterium targets are routinely used in extracted-beam experiments at the proton synchrotron COSY/Julich. The dimensions of a typical target cell are in the range of a few mm, with extremely thin window foils. A fast, only locally acting heating procedure for removing condensates from the cold foils was developed. Filling and operation with different liquefied gases is possible without breaking the vacuum. Higher luminosities for hydrogen targets can be reached by using CH 4 rather than H 2 liquids as qualitatively demonstrated for the pp →ppπ 0 reaction.

At COSY pp-bremsstrahlung was measured at a beam momentum of 797 MeV/c using an external proton beam. Data were taken with a wide angle spectrometer covering a solid angle of approximately 1 sr. The complete data set is presented in a series of c.m. angular distributions as well as a single Dalitz plot. The absence of final state interaction effects is understood as being due to a general insensitivity of the pp γ reaction to the spin-singlet component of the NN interaction. Coplanar angular distributions (in the laboratory system) are well reproduced by recent model calculations; also good agreement is found with the original TRIUMF data [K. Michaelian et al., Phys. Rev. D 41 (1990) 286] when omitting the rescaling factor of 2/3.

The reaction pp → K + Λp was measured exclusively at the cooler synchrotron COSY at beam momenta of p Beam = 2.50 GeV/c and p Beam = 2.75 GeV/c using the TOF detector. Angular and momentum distributions were obtained for the full phase space of the reaction products. Total cross sections were extracted to be (2.7 ± 0.3) μ b and (12.0 ± 0.4) μ b, respectively. The polarization of the Λ -hyperon was determined as a function of its transversal momentum and was found to be negative for transverse momentum transfers of p T ≥ 0.3 GeV/c. The results together with existing data are compared with phenomenological parametrizations and model calculations on the basis of meson exchange.

The first measurement of the helicity dependence of the photoproduction cross section of single neutral pions off protons is reported for photon energies from 600 to 2300 MeV, covering nearly the full solid angle. The data are compared to predictions from the SAID, MAID, and BnGa partial wave analyses. Strikingly large differences between data and predictions are observed, which are traced to differences in the helicity amplitudes of well-known and established resonances. Precise values for the helicity amplitudes of several resonances are reported.

Measurements of the pp → pK + Λ reaction at T p = 2.28 GeV have been carried out at COSY-TOF. In addition to the Λp FSI and N * resonance excitation effects a pronounced narrow structure is observed in the Dalitz plot and in its projection on the pΛ invariant mass. The strongly asymmetric structure appears at the pp → NK + Σ threshold and is interpreted as the ΣN cusp effect. The observed width of about 20 MeV/c 2 is substantially broader than anticipated from previous measurements as well as theoretical predictions. Angular distributions of this cusp structure are shown to be dissimilar to those in the residual pK + Λ channel, but similar to those observed in the pK + Σ 0 channel.

An array consisting of scintillating fibers embedded in a lead matrix was tested for use as a calorimeter for showers induced by energetic photons (50 MeV ≤ Eγ < 1 GeV). Experimentally, its efficiency was found to equal 100% for photon energies in excess of 100 MeV, the energy resolution is (σE) ≈ 10%(EγGeV)−12 over the full energy range. Extensive Monte Carlo studies show that the efficiency drops rapidly around Eγ = 40 MeV. The suitability of cosmic radiation for calibration purposes is demonstrated. Based on these studies design criteria for future arrays can be matched to experimental requirements.

The ANDA (Antiproton Annihilation at Darmstadt) experiment foresees many detectors for tracking, particle identification and calorimetry. Among them, the innermost is the MVD (Micro Vertex Detector) responsible for a precise tracking and the reconstruction of secondary vertices. This detector will be built from both hybrid pixel (two inner barrels and six forward disks) and double-sided micro strip (two outer barrels and outer rim of the last two disks) silicon sensors. A time-based approach has been chosen for the readout ASIC of the strip sensors. The PASTA (ANDA Strip ASIC) chip aims at high resolution time-stamping and charge information through the Time over Threshold (ToT) technique. It benefits from a Time to Digital Converter (TDC) allowing a time bin width down to 50 ps. The analog front-end was designed to serve both n-type and p-type strips and the performed simulations show remarkable performances in terms of linearity and electronic noise. The TDC consists of an analog interpolator, a digital local controller, and a digital global controller as the common back-end for all of the 64 channels.

The first measurement is reported of the double-polarization observable G in photoproduction of neutral pions off protons, covering the photon energy range from 620 to 1120 MeV and the full solid angle. G describes the correlation between the photon polarization plane and the scattering plane for protons polarized along the direction of the incoming photon. The observable is highly sensitive to contributions from baryon resonances. The new results are compared to the predictions from SAID, MAID, and BnGa partial wave analyses. In spite of the long-lasting efforts to understand {\gamma}p -> p{\pi} 0 as the simplest photoproduction reaction, surprisingly large differences between the new data and the latest predictions are observed which are traced to different contributions of the N (1535) with spin-parity J^P = 1/2^- and N (1520) with J^P = 3/2^- . In the third resonance region, where N (1680) with J^P = 5/2^+ production dominates, the new data are reasonably close to the predictions., Comment: Submitted for publication in PRL

Primary and secondary cross sections were measured for different exit channels of quasielastic collisions of 8 A · MeV 116 Sn with 48 Ti near the grazing angle. Angular and nuclide distributions were extracted from these data. The secondary projectile-like fragments were unambiguously resolved by means of a magnetic spectrometer. With the aid of a specifically designed detector system for recoiling target-like fragments, a complete reconstruction of primary exit channels and thus, the determination of primary cross sections were achieved for individual nuclides up to 50 MeV of total kinetic energy loss (TKEL) without using any model assumption. The comparison of primary and secondary quantities showed that secondary quantities represent only rough measures of primary ones. A qualitative explanation for the development of the system with increasing TKEL is found in the potential energy surface which appears to dominate the neutron exchange, while proton transfer proceeds independently of the potential.

Fragment velocities, masses, and energies from neutron-induced fission of 232 Th were measured at various neutron energies in the subthreshold-resonance region around E n ≅ 1.6 MeV and above threshold with good neutron-energy resolution. These quantities were obtained by three different methods using two different types of detectors, namely parallel plate avalanche counters for time of flight, and surface-barrier detectors for time of flight and pulse height measurements. Comparison of the different results and a careful error analysis clearly exhibit the limitation in resolution due to methodical uncertainties. Within these limits, none of the measured quantities shows dependencies on neutron energy.

Excitation energy spectra of primary products from quasielastic reactions at 8 A MeV between 116Sn and 48Ti were studied. The experimental setup rendered possible the unambiguous resolution of the primary channels with respect to charge and mass number as well as the determination of the primary total excitation energies. A linear relation between the average total excitation energy and the net number of transferred nucleons is observed, which is found to reflect the binding energies of the net transferred nucleons in their acceptor when changes of the Coulomb potential are taken into account in the case of charge transfer.

The partition of excitation energy between fragments from reactions of 8 A · MeV116Sn with48Ti was studied. The experimental setup rendered possible the unambiguous identification of primary fragments up to total excitation energies of 50 MeV. Neutron mulitplicities of both projectile-like and target-like fragments were experimentally determined as a function of excitation energy. Comparison of these quantities with the results of numerical calculations of sequential decay including rotation of the fragments allowed the determination of excitation energy partition and the associated fluctuations.

A combination of a parallel plate avalanche counter (PPAC) and an ionization chamber (IC) of conventional type with large solid angle was designed for the identification of slow heavy ions with A ≈ 50 and E = 1−2 A MeV. An important feature of this arrangement is that both detectors operate in the same low pressure gas volume. Using extremely thin foils the passive energy loss could be kept very small allowing rather good charge number and energy resolution. The PPAC provides both the information about the in-plane scattering angle and a fast timing signal, which can be combined with a reference signal for time-of-flight measurement and mass determination. The out-of-plane angle is obtained from the electron drift time within the IC.

The single-pion production reactions pp $ \rightarrow$ d $ \pi^{+}_{}$ , pp $ \rightarrow$ np $ \pi^{+}_{}$ and pp $ \rightarrow$ pp $ \pi^{0}_{}$ were measured at a beam momentum of 0.95GeV/c ( T p $ \approx$ 400 MeV) using the short version of the COSY-TOF spectrometer. The central calorimeter provided particle identification, energy determination and neutron detection in addition to time-of-flight and angle measurements from other detector parts. Thus all pion production channels were recorded with 1-4 overconstraints. The main emphasis is put on the presentation and discussion of the np $ \pi^{+}_{}$ channel, since the results on the other channels have already been published previously. The total and differential cross-sections obtained are compared to theoretical calculations. In contrast to the pp $ \pi^{0}_{}$ channel we observe in the np $ \pi^{+}_{}$ channel a strong influence of the $ \Delta$ excitation. In particular, the pion angular distribution exhibits a (3 cos2 $ \Theta$ + 1) -dependence, typical for a pure s -channel $ \Delta$ excitation and identical to that observed in the d $ \pi^{+}_{}$ channel. Since the latter is understood by a s -channel resonance in the 1 D 2 pn partial wave, we discuss an analogous scenario for the pn $ \pi^{+}_{}$ channel.

The realization of FAIR (Facility for Antiproton and Ion Research [1]) will pave the road towards a variety of experiments which will further our understanding of strong QCD. The \( \overline P \) ANDA experiment will explore the annihilation of antiprotons on hydrogen and heavy targets at energies of up to 15 GeV, while the CBM experiment focusses on the study of the properties of highly compressed nuclear matter. Both experiments will exploit state-of-the-art detection techniques to achieve spectroscopy of particles in a large energy and angular range.

The two-pion production reaction pp -> pp pi(+)pi(-) was measured with a polarized proton beam at T-p approximate to 750 and 800MeV using the short version of the COSY-TOF spectrometer. The implementation of a delayed-pulse technique for Quirl and central calorimeter provided positive pi(+) identification in addition to the standard particle identification, energy determination as well as time-of-flight and angle measurements. Thus all four-momenta of the emerging particles could be determined with 1-4 overconstraints. Total and differential cross-sections as well as angular distributions of the vector analyzing power have been obtained. They are compared to previous data and theoretical calculations. In contrast to predictions we find significant analyzing-power values up to A(y) = 0.3. The data taken in the energy region of the excitation of the Roper resonance confirm that its dominant pi pi decay channel is N* -> N sigma.

Elastic and inelastic scattering of 575 MeV {sup 36}Ar on {sup 208}Pb to low-lying states of both target and projectile nucleus were studied. The measured cross sections were analyzed with coupled-channels calculations. A very satisfying description of the data was obtained by using {ital B}({ital EL}) values from the literature and proper optical potential parameters. The latter were used as basis to estimate the cross sections for the excitation of the isovector giant dipole and isoscalar giant quadrupole resonances.

One of the experimental programs at the TOF spectrometer located at the COSY-accelerator (Forschungszentrum Jülich, Germany) is the study of ω-meson production in proton proton collisions (pp → ppω). Recently, a measurement was performed with a polarized beam at an excess energy of ∊ = 129 MeV , which offers the possibility to analyze polarization observables of this reaction channel for the first time. The analyzing power (Ay) of the pp → ppω-reaction was determined to be compatible with zero.