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For the first time the 4π γ-ray spectrometer EUROGAM II has been coupled to a 4π light charged particle detector array, DIAMANT, during a test experiment on the reaction 32 S + 58 Ni at 120 MeV beam energy. A very large improvement in the peak-to-background ratio of the γ-spectra has been found when EUROGAM II is triggered by DIAMANT to select an exit channel. A simple algebra has been developed which provides theoretical estimates in good agreement with these experimental results. It is demonstrated that, depending on both the γ-spectrometer and ancillary detector performances, much better peak-to-background can be obtained by such a coupling. For the same peak-to-background ratio, the use of an ancillary detector allows for a lower γ-ray coincidence level and therefore improves the statistics. Ways to select the most appropriate ancillary detector are given. The ability of the ancillary detector to provide a total Doppler shift correction is crucial for the improvement of the peak-to-background ratio.

Using the 4$\ensuremath{\pi}$ light charged-particle detector DIAMANT in combination with the $\ensuremath{\gamma}$-ray spectrometer EUROGAM II, the decay of the ${}^{90}$Ru compound nucleus via the $p\ensuremath{\alpha}$ channel was studied. These nuclei were produced at an excitation energy of 54.9 MeV and with a maximum angular momentum of 37$\ensuremath{\Elzxh}$ by the 120 MeV ${}^{32}$S + ${}^{58}$Ni reaction. The measurement of the energy of the two particles allowed the determination of the energy distribution of the entry states. A particular behavior of the sharing of the available energy between the two particles was found: For increasing values of the entry-state energy, the mean energy for protons remains almost constant while for alpha particles it decreases. This behavior is well reproduced by the evaporation code LILITA_N95. The physics underlying the decay is discussed in the framework of the statistical model which predicts a strong correlation between the excitation energy and the angular momentum of the evaporation residue. This result encourages the use of the $p\ensuremath{\alpha}$ channel to select the excitation energy and the angular momentum of the evaporation residue for superdeformed band studies.

A method based on the conservation of linear momentum is used to correct the position and the width of the γ-ray lines of the residual nucleus produced in heavy-ion induced fusion–evaporation reactions. This method implies the measurement of the total number of the emitted particles, their masses, energies and directions of emission in coincidence with the prompt γ-rays. It has been applied to the 120 MeV 32 S + 58 Ni reaction whose data have been collected using the high efficiency and large granularity 4π light charged particle detector DIAMANT, coupled to the 4π γ-ray spectrometer EUROGAM II.

The decay of Ru-90 compound nucleus via the p-alpha channel (about 1% of the fusion cross-section) was studied using the 4pi light charged-particle detector DIAMANT coupled to the gamma-ray spectrometer EUROGAM-II. The high selectivity of the apparatus allowed the determination of the total kinetic energy of the two particles with good statistics. Particle energy spectra and angular correlations have been analysed as a function of the excitation energy of the entry states and compared to statistical model calculations. As the excitation energy of the entry states increases, the mean energy carried out by the protons remains almost constantwhereas the one of the alpha particle decreases. This behaviour is well reproduced by the evaporation code LILITA_N85, which predicts a strong correlation between the excitation energy and the angular momentum of the evaporation residues. This findings could help to enhance the population of superdeformed bands by using the total kinetic energy of the two particles as a gating condition.

The coupling of efficient particle and gamma detection arrays is a powerful tool to study the deexcitation of both compound and residual nuclei in fusion evaporation reactions. We show first results obtained coupling the DIAMANT (4 pi light charged particle array) and EUROGAM (4 pi gamma array) detectors demonstrating the improvement in the resolving power by this combination. For gamma rays of similar or equal to 800keV improvements in the Doppler correction up to 50% have been reached for the 2 alpha exit channel following the fusion of S-32+Ni-58 at 120 MeV bombarding energy (beta similar or equal to 3%).

We describe the electronics and data acquisition system of the 4π light particle multidetector array DIAMANT. This system has been conceived to be very modular with regard to both the kind and number of detectors. The whole system is designed to run either with a few additional ancillary detectors (Ge) or linked to 4π γ arrays such as EUROGAM. Part of the electronics has been designed using SMD devices; the acquisition is based on CAMAC ADCs and VME units for data acquisition, data transfer is handled via a 32 bit ECL bus (DT32) used for EUROGAM. The data acquisition, distributed on a network, is based on the VxWorks Real Time kernel and the UNIX Operating System.

Using the 4 pi light charged-particle detector DIAMANT in combination with the gamma-ray spectrometer EUROGAM II, the decay of the Ru-90 compound nucleus via the p alpha channel was studied. These nuclei were produced at an excitation energy of 54.9 MeV and with a maximum angular momentum of 37 (h) over bar by the 120 MeV S-32 + Ni-58 reaction. The measurement of the energy of the two particles allowed the determination of the energy distribution of the entry states. A particular behavior of the sharing of the available energy between the two particles was found: For increasing values of the entry-state energy, the mean energy for protons remains almost constant while for alpha panicles it decreases. This behavior is well reproduced by the evaporation code LILITA_N95. The physics underlying the decay is discussed in the framework of the statistical model which predicts a strong correlation between the excitation energy and the angular momentum of the evaporation residue. This result encourages the use of the p alpha channel to select the excitation energy and the angular momentum of the evaporation residue for superdeformed band studies.

Energy and angular distributions of the fast outgoing electron beam induced by the interaction of a 1 J, 30 fs, 2 x 10(19) W/cm(2), 10 Hz laser with a thin foil target are characterized by electron energy spectroscopy and photonuclear reactions. We have investigated the effect of the target thickness and the intensity contrast ratio level on the electron production. Using a 6-microm polyethylene target, up to 4 x 10(8) electrons with energies between 5 and 60 MeV were produced per laser pulse and converted to gamma rays by bremsstrahlung in a Ta secondary target. The rates of photofission of U as well as photonuclear reactions in Cu, Au, and C samples have been measured. In optimal focusing conditions, about 0.06% of the laser energy has been converted to outgoing electrons with energies above 5 MeV. Such electrons leave the target in the laser direction with an opening angle of 2.5 degrees.

Reaction times for two right handed subjects who received 6000 trials of dichotic CVs were obtained under response conditions involving the left hand, right hand, and axial movements [Geschwind, Am. Sci. 63 (2), 188–195 (1975)]. The simultaneous CVs were presented in a target‐challenge paradigm (Berlin et al., IEEE Trans. Audio Electroacoust. AU‐21, 189 (1973)]. The results indicated that when the targets were presented to the right ear, the latencies were shorter (150+ msec) than when presented to the left ear. The large and stable differences in latencies remained invariant with the mode of response. Phonetic effects involving manner and place of articulation will be discussed. The relationship between the obtained measures of latency and percent correct are also included. [Supported by National Institutes of Health, USPHS Grant No. NH 11647‐02.]