Search

Based on the KASCADE multi-detector system with its large hadron calorimeter and using the CORSIKA simulation program with the implemented high-energy hadronic interaction models QGSJET, VENUS, DPMJET, SIBYLL, and HDPM, a method for the test of models by comparing el ent rates is described. Preliminary results show differences of the model predictions both among each other and when confronted with measurements. The rates are strongly influenced by the inelastic cross sections and the elasticity, especially by the contribution of diffractive dissociation. The discrepancy to measurements at primary energies below similar or equal to 3 (.) 10(13) eV can be reduced by increasing the non-diffractive inelastic cross section.

To investigate the impact of uncertainties in the knowledge of properties of individual hadronic interactions on the development of extensive air showers, the inelastic proton-proton cross section and the elasticity of interactions have been modified within the interaction model QGSJET. Air shower simulations are performed using the CORSIKA code. The influence of the modifications on observables like the number of electrons, muons, and hadrons registered at ground level are investigated. The predictions are compared to measurements of the KASCADE experiment.

In the presented analysis of air shower data measured with the KASCADE experiment energy spectra for five mass groups are reconstructed. The results show a change of composition towards heavier elements across the knee but also demonstrate an insufficient description of the data by the used hadronic interaction models QGSJet and SIBYLL.

Recent results from the KASCADE experiment on measurements of cosmic rays in the energy range of the knee are presented. Emphasis is placed on energy spectra of individual mass groups as obtained from an two-dimensional unfolding applied to the reconstructed electron and truncated muon numbers of each individual EAS. The data show a knee-like structure in the energy spectra of light primaries (p, He, C) and an increasing dominance of heavy ones (A > 20) towards higher energies. This basic result is robust against uncertainties of the applied interaction models QGSJET and SIBYLL which are used in the shower simulations to analyse the data. Slight differences observed between experimental data and EAS simulations provide important clues for further improvements of the interaction models. The data are complemented by new limits on global anisotropies in the arrival directions of CRs and by upper limits on point sources. Astrophysical implications for discriminating models of maximum acceleration energy vs galactic diffusion/drift models of the knee are discussed based on this data., 8 pages, 7 figures, to appear in Nuclear Physics B, Proceedings Supplements, as part of the volume for the CRIS 2004, Cosmic Ray International Seminar: GZK and Surroundings

The muon detection facilities of the Central Detector of the cosmic ray experiment KASCADE(-Grande) have been extended by a system of limited streamer tube (LST) detectors, recently brought into operation. This detector system improves the efficiency and the multiplicity resolution of the high-energy muon detection by the setup of large-area position sensitive wire proportional chambers (MWPC) of the Central Detector, currently used in extensive air showers (EAS) investigations of KASCADE. The present work describes the technical layout and operation of the LST system, the methods and procedures for studying the characteristics and performance of this detector component, and the reconstruction of basic EAS observables: the total number, the density and the spatial distributions of EAS particles registered with the LST system. Special emphasis is put on the discussion of the uncertainties. Average number of hits as well as muon number (for E μ > 2.4 GeV ) and density spectra are presented for illustrating the operation of the LST. The information about the spatial pattern is parameterized in terms of fractal moments. The information content of the EAS observables of the LST system is demonstrated using Monte Carlo simulations with the program CORSIKA.

KASCADE has been designed to measure air showers of primary cosmic-ray energies in the PeV region and to investigate the knee phenomenon in the all-particle energy spectrum. Several observations are measured simultaneously for each event by different detector systems. The experiment started to take data in 1996 and has been completed and extended since then. The individual detector systems and their performances are described. Also, the experience in long-term operation of the experiment and the interplay between different components is outlined.

Frequency distributions of local muon densities in high-energy extensive air showers (EAS) are presented as signature of the primary cosmic ray energy spectrum in the knee region. Together with the gross shower variables like shower core position, angle of incidence, and the shower sizes, the KASCADE experiment is able to measure local muon densities for two different muon energy thresholds. The spectra have been reconstructed for various core distances, as well as for particular subsamples, classified on the basis of the shower size ratio N μ / N e . The measured density spectra of the total sample exhibit clear kinks reflecting the knee of the primary energy spectrum. While relatively sharp changes of the slopes are observed in the spectrum of EAS with small values of the shower size ratio, no such feature is detected at EAS of large N μ / N e ratio in the energy range of 1–10 PeV. Comparing the spectra for various thresholds and core distances with detailed Monte Carlo simulations the validity of EAS simulations is discussed.

The experiment KASCADE observes simultaneously the electron–photon, muon, and hadron components of high-energy extensive air showers (EAS). The analysis of EAS observables for an estimate of energy and mass of the primary particle invokes extensive Monte Carlo simulations of the EAS development for preparing reference patterns. The present studies utilize the air shower simulation code corsika with the hadronic interaction models VENUS, QGSJet and Sibyll, including simulations of the detector response and efficiency. By applying non-parametric techniques the measured data have been analyzed in an event-by-event mode and the mass and energy of the EAS inducing particles are reconstructed. Special emphasis is given to methodical limitations and the dependence of the results on the hadronic interaction model used. The results obtained from KASCADE data reproduce the knee in the primary spectrum, but reveal a strong model dependence. Owing to the systematic uncertainties introduced by the hadronic interaction models no strong change of chemical composition can be claimed in the energy range around the knee.

KASCADE (KArlsruhe Shower Core and Array DEtector) is a multi-detector setup to observe the electromagnetic, muonic and hadronic air shower components simultaneously in the energy region around the “knee” of the primary spectrum. Its main aim is to determine energy spectrum and composition of hadrons in primary cosmic rays. This is attempted by registring a large number of observables for each EAS including measurements of electrons, muons and hadrons. This contribution gives a short description of the experiment and then presents some results on the lateral distributions of various particle types and on the spectrum of hadrons. The status of our analyses to determine mass composition is presented in an accompanying contribution by A. Haungs.

KASCADE (KArlsruhe Shower Core and Array DEtector) is a multi-detector setup to observe the electromagnetic, muonic and hadronic air shower components simultaneously at primary energies in the region of the “knee”. A large number of observables per single shower are registered. The main aims of the experiment are the determination of the primary energy spectrum around the “knee” and the energy variation of the chemical composition. The measurements reveal an increasing mean mass of the primary cosmic rays above the observed kink, and a sharper knee for the light primary component than for the all-particle spectrum, and the absence of a knee for the heavy component between 1 and 10 PeV.

New data on the muon/electron ratio derived from the KASCADE extensive air shower experiment are presented. This ratio is known to be the most sensitive parameter in the determination of the mass of the primary particle when using ground array data. The particle numbers are measured with the KASCADE array comprising 500 m 2 of e/γ- and 620 m 2 of μ - detectors. The primary mass is inferred on an event-by-event basis by comparing the experimental data to corresponding EAS simulations. We observe a change towards a heavier composition with increasing energy above the knee. The sensitivity of this result to the specific hadronic interaction model employed in the simulations (e.g. VENUS and QGSJET) is discussed.

Physical review / C 57(2), 602 - 611 (1998). doi:10.1103/PhysRevC.57.602, The proton decay of spin-isospin strength in 90Nb was investigated after excitation via the reaction 90Zr(6Li,6He)90Nb at 156 MeV bombarding energy. The Gamow-Teller (GT) strength distribution and corresponding B(GT) values were extracted from singles spectra measured at extreme forward angles including zero degree. Protons in coincidence with 6He ejectiles were detected using a multidetector arrangement of semiconductor strip detectors. Relative branching ratios and 6He-p angular correlations have been measured for a proton decay to well defined low lying single hole states in 89Zr. Evidence for a dominant statistical decay has been found in the whole observed region of excitation energy; a small direct decay component, however, cannot be ruled out. In the region of the Gamow-Teller giant resonance between 8.0 and 12.0 MeV excitation energy additional strength with higher mulitpolarities L>~1 was identified from a comparison with predictions in the statistical decay model. At higher excitation energies above the giant resonance region the decay characteristics confirm the presence of a flat distribution of Gamow-Teller strength., Published by Inst., Woodbury, NY

A Limited Streamer Tube (LST) detector system has been installed at the KASCADE-Grande experiment to study the Extensive Air Showers (EAS) muon component above a threshold of 2.4 GeV. The extended area of 255 m2 of the LST and the fine granularity of detection enables a detailed study of the muon spatial distribution in the very central zone of the air shower. A dedicated, fractal based analysis has been developed to take advantage of the observables of this detector setup. The sensitivity on cosmic rays mass and energy discrimination has been verified, based on 1.5 years of data collection by the KASCADE experiment.

The KASCADE-Grande experiment extends the existing extensive air shower experiment KASCADE by an array of 37 detector stations spread over an area of 0.5 km2. The new Grande array measures the charged component of the showers. To reconstruct the mass composition of the cosmic rays, additional information from the muon component of air showers is required. Using observables from the new Grande array together with the muon detectors of the original KASCADE array provides a possibility to reconstruct also the total muon number of each air shower. The quality of reconstruction based on comparison with simulated data, as well as first results of a reconstructed muon size spectrum are presented.

LOFAR is a new digital radio interferometer that is being build in The Netherlands. By sampling the radio waves with fast ADCs it can digitally store the whole waveform information and analyze transient events like air showers after they have been recorded. To demonstrate its ability to measure air showers we are building LOPES (a LOFAR PrototypeStation) at the site of an existing air shower array (KASCADE-Grande). The first phase consisting of 10 antennas is already running. It has demonstrated how digital interference suppression and beamforming can overcome the problem of radio interference and pick out air shower events.

KASCADE (KArlsruhe Shower Core and Array DEtector) is determining flux spectra for different primary mass groups to disentangle the knee feature of the primary cosmic-ray energy spectrum. The energy spectra of the light element groups result in a knee-like bending and a steepening above the knee. The topology of the individual knee positions suggests a rigidity dependence. To proof the rigidity dependence the KASCADE array is now extended by a factor 10 in area. The major goal of KASCADE-Grande is the observation of the ’iron-knee’ in the cosmic-ray spectrum at around 100 PeV which is expected following the KASCADE observations. PACS: 98.70.Sa Cosmic rays

The isoscalar giant monopole resonance in the nucleus {sup 24}Mg was investigated by inelastic {sup 6}Li scattering at {ital E}{sub Li}=156 MeV. At extreme forward angles fragmented {ital E}0 strength was observed up to {ital E}{sub {ital x}}=23 MeV. The extracted strength centered at 18.3{plus_minus}0.5 MeV excitation energy with a width of {Gamma}=4.8{plus_minus}0.5 MeV corresponds to 97.3%{plus_minus}15% of the {ital E}0 energy weighted sum rule.

The temporal structure of the extensive air shower (EAS) muon component (E-thres = 2.4 GeV) is studied at sea level by measurements of the muon arrival time distributions using the muon detection facilities of the KASCADE central detector. Data have been analysed for EAS core distances up to 110 m for primary energies around the knee region. The time structure of the EAS muon component is represented by the distributions of the mean, median, first quartile and the third quartile of the muon arrival time distributions relative to the foremost muon. The EAS time profiles (variation with the distance from the EAS center) are studied along their dependencies on the angle of incidence and the energy-indicative muon number N-mu(tr). Effects of the fluctuation of the arrival time of the first registered muon are scrutinised and corrected. The experimental results are compared with EAS Monte Carlo (CORSIKA-GEANT) simulations, fully including the detector responses and illustrating the phenomenological features. The comparisons, though generally in fair global agreement, revealed that the simulations underestimate the shower thickness and show nearly no dependence on the mass composition if the time resolution of the apparatus is realistically taken into account. (C) 2001 Elsevier Science B.V. All rights reserved.

In a recent publication Schatz [Astropart. Phys. (2003), this issue] argues that unambiguous results about energy distributions of primary cosmic-ray mass groups can only be obtained from measured air shower observables if their mutual correlations are explicitly taken into account. This statement is used to challenge preliminary results presented by the KASCADE Collaboration at the International Cosmic Ray Conference in Hamburg, 2001 [KASCADE Collaboration, 27th ICRC, Hamburg, 2001, p. 97; KASCADE Collaboration, Invited Rapporteur and Highlight Papers of ICRC 2001, p. 240]. In this comment it is argued that the criticism of Schatz does not apply to the aforementioned analysis of KASCADE data.

The main goals of the KASCADE (KArlsruhe Shower Core and Array DEtector) experiment are the determination of the energy spectrum and elemental composition of the charged cosmic rays in the energy range around the knee at ca. 5 PeV. Due to the large number of measured observables per single shower a variety of different approaches are applied to the data, preferably on an event-by-event basis. First results are presented and the influence of the high-energy interaction models underlying the analyses is discussed., 3 pages, 3 figures included, to appear in the TAUP 99 Proceedings, Nucl. Phys. B (Proc. Suppl.), ed. by M. Froissart, J. Dumarchez and D. Vignaud

First investigations of the reaction12C(6Li,6He)-12N(p)11C were used to study spin-isospin strength in the nucleus12N at ELi=156 MeV. While the6He ejectiles were detected at θHe=0° using a magnetic spectrograph, the decay protons were analysed in a wide range of backward angles (100°

The ${(}^{6}$Li${,}^{6}$He) reaction was studied on the nuclei $^{37}\mathrm{Cl}$ and $^{71}\mathrm{Ga}$ at ${\mathit{E}}_{6\mathrm{L}\mathrm{i}}$=156 MeV at extreme forward angles including zero degree. Gamow-Teller strength and the corresponding B(GT) values were extracted. It is shown that these measurements provide an alternative method to calibrate solar neutrino detectors.

Coulomb dissociation of light nuclear projectiles in the electric field of heavy target nuclei has been experimentally investigated as an alternative access to radiative capture cross sections at low relative energies of the fragments, which are of astrophysical interest. As a pilot experiment the breakup of 156 MeV {sup 6}Li projectiles at {sup 208}Pb with small emission angles of the {alpha} particle and deuteron fragments has been studied. Both fragments were coincidentally detected in the focal plane of a magnetic spectrograph at several reaction angles well below the grazing angle and with relative angles between the fragments of 0{degree}--2{degree}. The experimental cross sections have been analyzed on the basis of the Coulomb breakup theory. The results for the resonant breakup give evidence for the strong dominance of the Coulomb dissociation mechanism and the absence of nuclear distortions, while the cross section for the nonresonant breakup follows theoretical predictions of the astrophysical {ital S} factor and extrapolations of corresponding radiative capture reaction cross section to very low c.m. energies of the {alpha} particle and deuteron. Various implications of the approach are discussed.

The ({sup 6}Li,{sup 6}He) reaction was studied on the target nuclei {sup 48}Ca and {sup 90}Zr at {ital E}{sub Li}=156 MeV at extreme forward reaction angles. From the zero degree spectra Gamow-Teller strength was extracted for excitation energies 0{le}{ital E}{sub {ital x}}{approx lt}20 MeV. The results are compared with distorted-wave Born approximation calculations and ({ital p},{ital n}) data.

The ${(}^{6}$Li${,}^{6}$He) reaction was studied on targets of $^{12}\mathrm{C}$, $^{18}\mathrm{O}$, $^{26}\mathrm{Mg}$, and $^{42}\mathrm{Ca}$ at a beam energy of 156 MeV. Zero degree measurements of all systems are presented. The evaluated cross sections for Gamow-Teller transitions at \ensuremath{\theta}=0\ifmmode^\circ\else\textdegree\fi{} and the corresponding strengths of analogous beta decays are compared.

Occasionally cosmic-ray induced air showers result in single, unaccompanied hadrons at ground level. Such events are investigated with the 300 m2 hadron calorimeter of the KASCADE-Grande experiment. It is an iron sampling calorimeter with a depth of 11 hadronic interaction lengths read out by warm-liquid ionization chambers. The longitudinal shower development is discussed as function of energy up to 30 TeV and the results are compared with simulations using the GEANT/FLUKA code. In addition, results of test measurements at a secondary particle beam of the Super Proton Synchrotron at CERN up to 350 GeV are discussed.

Recent results from the multi-detector set-up KASCADE on measurements of cosmic rays in the energy range of the so called "first" knee (at ≈ 3 PeV) indicate a distinct knee in the energy spectra of light primary cosmic rays and an increasing dominance of heavy ones towards higher energies. This leads to the expectation of knee-like features of the heavy primaries at around 100 PeV. To investigate this energy region KASCADE has recently been extended by a factor 10 in area to the new experiment KASCADE-Grande. Main results of KASCADE as well as set-up, capabilities, and status of KASCADE-Grande are presented.

Radio pulses emitted in the Atmosphere during the air shower development of high-energy primary cosmic rays were measured during the late 1960ies in the frequency range from 2 MHz to 520 MHz. Mainly due to difficulties with radio interference these measurements ceased in the late 1970ies. LOFAR (Low Frequency Array) is a new digital radio interferometer under development. Using high bandwidth ADCs and fast data processing it it will be able to filter out most of the interference. By storing the whole waveform information in digital form one can analyze transient events like air showers even after they have been recorded. To test this new technology and to demonstrate its ability to measure air showers a "LOFAR Prototype Station" (LOPES) is set up to operate in conjunction with an existing air shower array (KASCADE-Grande). The first phase consisting of 10 antennas is already running. It operates in the frequency range of 40 to 80 MHz, using simple short dipole antennas and direct 2nd Nyquist sampling of the incoming wave. It has proven to be able to do simple astronomical measurements, like imaging of a solar burst. It has also demonstrated how digital interference suppression and beamforming can overcome the problem of radio interference and pick out air shower events.

KASCADE-Grande is the extension of the multi-detector setup KASCADE to cover a primary cosmic ray energy range from 100 TeV to 1 EeV. The enlarged EAS experiment provides comprehensive observations of cosmic rays in the energy region around the knee. Grande is an array of 700 x 700 sqm equipped with 37 plastic scintillator stations sensitive to measure energy deposits and arrival times of air shower particles. LOPES is a small radio antenna array to operate in conjunction with KASCADE-Grande in order to calibrate the radio emission from cosmic ray air showers. Status and capabilities of the KASCADE-Grande experiment and the LOPES project are presented., Comment: To appear in Nuclear Physics B, Proceedings Supplements, as part of the volume for the CRIS 2004, Cosmic Ray International Seminar: GZK and Surroundings

The main aim of the KASCADE extensive air shower (EAS) experiment is the determination of the chemical composition of cosmic rays in the energy range around and above the knee at Ek ≈ 3 PeV. A large number of observables are measured simultaneously for each individual event, by the combination of various detection techniques for the electromagnetic, the muonic, and the hadronic component of the extensive air showers. Detailed investigations have been performed with the data measured by the KASCADE experiment since the start of data taking at the end of 1995. The results allow to evaluate hadronic interaction models, used in simulations to interpret air shower data. The all-particle spectrum of cosmic rays and their mass composition, as well as individual spectra for groups of elements have been reconstructed in the energy range between 1015 and 1017 eV . The results suggest, the knee in the all-particle cosmic-ray energy spectrum is caused by a rigidity-dependent cut-off of individual element groups. To improve the statistics around 1017 eV, where the “iron knee” in the cosmic ray spectrum is indicated in our data, the KASCADE experiment has recently been extended to KASCADE-Grande by a large collecting area (0.5km2) electromagnetic array, contributed from the former EAS-TOP experiment. The Grande part will cover the primary energy range 1016 eV

An analysis of muon and hadron rates observed in the central detector of the KASCADE experiment has been carried out. The data are compared to CORSIKA simulations employing the high-energy hadronic interaction models QGSJET, DPMJET, HDPM, SIBYLL, and VENUS. In addition, first results with the new hadronic interaction model neXus 2 are discussed. Differences of the model predictions, both among each other and when confronted with measurements, are observed. The hadron rates mainly depend on the inelastic cross-section and on the contribution of diffraction dissociation. The discrepancy between simulations and measurements at low primary energies around 5 TeV can be reduced by increasing the non-diffractive part of the inelastic cross-section of nucleon-air interactions. Examination of hadron multiplicities points towards harder spectra of secondary pions and kaons needed in the calculations., 14 pages, 7 figures, corresponding author: M. Risse, accepted for publication in J. Phys. G: Nucl. Part. Phys

A detector system for directional and time correlation measurements of multiple cosmic muons has been set up within the extensive air shower experiment KASCADE. The system consists of two layers (129 m(2) area each) of position-sensitive multiwire proportional chambers (MWPC) triggered by a layer of segmented plastic scintillation counters placed upon an iron/concrete shielding above the MWPCs. Operation conditions and performance of the MWPCs have been studied by means of a prototype arrangement consisting of a stack of four detectors and two trigger layers. Results of the detailed prototype studies are presented and discussed. In particular, it has been found that for the present purposes an operation with a commonly used argon-methane gas mixture instead of previously used argon-isobutane leads to an excellent performance. The chambers are integrated into the KASCADE experiment as described and are in continuous operation since 1996. Some typical measurements with the full detector assembly are used to illustrate which features of extensive air showers can be studied. (C) 2001 Elsevier Science B.V. All rights reserved.

The experimental results of the KASCADE Extensive Air Shower experiment have been searched for events which might be attributed to high energy primary gamma rays. The observed data are compared with simulated gamma showers. Events with a very low muon to electron ratio, a smooth lateral electron distribution and an age characteristic of gamma induced events are selected. This contribution describes the applied methods. So far only a very small fraction of the KASCADE results has been studied and no positive identification can yet be claimed.

Differential cross sections have been measured for the elastic and inelastic scattering of 104 MeV alpha-particles from90, 92Zr. The experimental data are analyzed in terms of coupled channels on the basis of a flexible anharmonic vibrator model and using different parametrizations of the radial shape of the extended optical potential. The results favour the squared Saxon-Woods type for the real part. Additionally to a radial momentum analysis of the real potentials a semimicroscopic folding model has been applied for extracting isoscalar quadrupole and hexadecapole transition rates.

Intermediate mass fragment cross-sectionsσ(E, θ, 4≤Z≤11) have been measured in the reaction6Li+46Ti at 156 MeV incident energy. A simple sequential binary decay model describes most of theZ>8 data as evaporation from the compound nucleus. The complete fusion cross-section is also well reproduced. An intermediate velocity source model (β=2β CN, T=7 MeV) has been used in order to explain the small angle and Z≤8 data which indicate aZ −4.1 dependence.

Inclusive alpha particle and deuteron spectra from collisions of 156 MeV6Li-ions with12C and208Pb were measured at extreme forward emission angles including zero degree. The measurements were performed with the Karlsruhe magnetic spectrograph ‘Little John’ and required an efficient reduction of the background from small-angle scattering. The observed double differential cross sections and angular distributions have been analysed on the basis of Serber's spectator break-up model. When going to angles smaller than grazing, where Coulomb effects are expected to be dominating, transitional features may appear. Corresponding effects probably associated with Coulomb break-up are observed with the208Pb-target and require a slight extension of the Serber approach. In the case of the12C-target the break-up cross sections in forward direction seem to reflect the shape of the internal momentum distribution of the alpha particle and deuteron cluster in the6Li-projectile and are in agreement with a 2S-type wave function. However, at larger angles the shape appears to be distorted, possibly by final state interactions.

The triple-differential cross sections for elastic break-up of 156 MeV 6 Li projectiles by the reactions 208 Pb( 6 Li, αd) 208 Pb g.s. and 12 C( 6 Li, αd) 12 C g.s. have been measured with large asymptotic relative momenta of the outgoing fragments. The data exhibit rather unfamiliar shapes of the energy spectra, often replacing the usual bell-shape distributions by double-peaked structures and varying rapidly with the relative emission angles. The origin of these features has been explored and the cross sections have been analysed on the basis of a diffractive disintegration approach.

Inclusive charged particle spectra were measured from nuclear reactions induced by 156 MeV 6Li on 40Ca. At forward angles the spectra exhibit broad break-up distributions centered around the energy corresponding to the beam velocity. The double differential cross sections together with previous results for a 208Pb target were analyzed in the framework of the DWBA approach to projectile break-up taking into account elastic and inelastic reactions of the break-up fragments. The high energy tails of the background due to preequilibrium emission of complex charged particles were estimated on the basis of the coalescence model.

The break-up of 156 MeV6Li ions colliding with12C,60Ni,90Zr,120Sn and208Pb has been experimentally studied. It was found that the break-up cross section decreases rapidly with increasing emission angles of the fragments and increases with increasing target mass. It comprises a fairly large fraction of the total reaction cross section. The observed features suggest that the6Li fragmentation is mainly a peripheral process, and is dominated by the cluster properties of the incident projectile. A simple plane-wave break-up model gives a rather good description of the shapes of the break-up bumps. The angular distributions of the fragments emitted in the6Li+208Pb reaction reveal the transition from peripheral break-up to incomplete fusion processes by which beam-velocity fragments are captured by the target nucleus. In addition to the (α+d) dissociation the (3He+t) break-up has been observed, but the triton spectra appear to be rather complex indicating further components due to more complicated reaction paths.

The measured ion-optical properties of the Karlsruhe magnetic spectrograph “Little John” and the properties of its detector system are described. Moreover, the procedures for an efficient use of the spectrograph, in particular concerning small angle and zero degree experiments, are presented in detail. Characteristic experimental results from 6 Li-induced nuclear reactions demonstrate the performance of the whole setup.

Precisely measured differential cross sections for elastic and inelastic scattering from 104 MeV alpha-particles by48Ca,50Ti and52Cr are reported. The analyses aim primarily at the determination of strength, radial shapes and deformation of the scattering potentials, looking for isotonic differences ofN=28 isotones. The mean square radii of the (real) potentials are discussed in terms of mean square radius differences of the matter distributions. The isoscalar transition rates derived by coupled channel analyses of the measured cross sections are compared with electromagnetic rates. In addition to the analyses on the basis of a slightly generalized extended optical model a semi-microscopic deformed folding model has been applied, using a density-dependent effective alpha-bound nucleon interaction. Though an excellent description of the data over the full angular range is obtained the resulting values of the deformation parameters appear to be not consistent with results from various different methods.

Reaction products from 6 Li-induced reactions on 40 Ca at 156 MeV have been studied using the d E × E identification as well as the inclusive γ-ray method. The complete fusion cross section has been found to be σ F = 67 ± 20 mb. The Z -distribution of fusion evaporation residues is compared with statistical model predictions. The Z -spectrum of reaction products shows a maximum at 15 ≲ Z ≲ 20, probably due to transfer and to incomplete fusion. It is suggested that the small value of the fusion cross section is due to the strong competition of 6 Li break-up processes.

The (/sup 6/Li,/sup 6/Li') reaction was studied on /sup 12/C at E/sub Li/ = 156 MeV at extreme forward angles including theta = 0/sup 0/. Spectra were taken in the excitation energy region E/sub x/approx.

Single nucleon transfer reactions in collisions of 156 MeV6Li ions with6Li nuclei, leading to unstable final nuclei (5Li,5He) have been experimentally studied. The measured6Li(6Li,7Li)5Ligr and6Li(6Li,7Be)5Hegr differential cross sections have been analysed on the basis of a FR-DWBA procedure, looking to which extent the entrance channel optical potentials may account for the unknown exit channel potentials.

A magnetic spectrograph for charged-particle spectroscopy, named “Little John”, consisting of two quadrupoles, one dipole and one sextupole magnet was constructed and put into operation at the Karlsruhe isochronous cyclotron. The ion-optically rather simple system covers a particle rigidity of 2.5 Tm and was especially designed for small reaction angle experiments. A modest resolving power of p/Δp = 5200, a momentum acceptance of (pmax − pmin)pmean = 20% and an acceptance solid angle of ω > 1 msr were the design goals. The momentum dispersion and consequently the acceptance of the spectrograph can be varied by a factor of 2 without varying other imaging properties considerably. The design, construction and equipment of the spectrograph are described.

The cross sections for nonelastic break-up modes have been studied for the 6Li + 40Ca reaction at ELi = 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 σb.unon = 582 ± 110 mb has been found. Together with results of inclusive charged-particle measure- ments we infer for the total break-up cross section σb.utot = 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.

Differential cross sections for elastic scattering of 104 MeV ..cap alpha.. particles from /sup 40,42,44,48/Ca have been measured with high angular accuracy over a wide angular range. Optical model analysis based on a Fourier-Bessel description of the real potential reveals isotopic differences which, in particular for /sup 48/Ca, indicate a small neutron skin.

It is shown that emission of intermediate mass fragments in a wide range of masseanand angles can be well described by sequential binary decay of the equilibrated compound system produced in the 26 MeV/A 6 Li+Ag reaction.

We present the design and first test results of a new FADC-based data acquisition (DAQ) system for the Grande array of the KASCADE-Grande experiment. The original KASCADE experiment at the Forschungszentrum Karlsruhe, Germany, has been extended by 37 detector stations of the former EAS-TOP experiment (Grande array)to provide sensitivity to energies of primary particles from the cosmos of up to $10^{18}$ eV. The new FADC-based DAQ system will improve the quality of the data taken by the Grande array by digitizing the scintillator signals with a 250 MHz sampling rate. events per second. Two Grande stations have been equipped with the FADC-based data acquisition system and first data are shown., Comment: 7 pages, 8 figures