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The flight model of the digital front-end electronics (DFEE) of the gamma-ray spectrometer SPI has been recently integrated on the INTEGRAL satellite spacecraft. The processing core of the DFEE is based on a dedicated application specific integrated circuit (ASIC). We report on the unified design and test methodology that was deployed to cover the entire life cycle of this subsystem, from initial design simulation to operational self-test and diagnosis operations after launch. Strong emphasis is put on the ASIC design-for-test strategies, from very-high speed integrated circuit description language IEEE 1076 (VHDL) simulation and test bench validation to full scan fabrication test coverage and inflight self-test capability.

A permanent magnet undulator has been developed at the CEA for the CLIO infrared free electron laser at Orsay. This undulator consists of two independent parts, of equal length ( l = 0.96 m) and of period λ 0 = 4 cm. The magnetic gap can be adjusted separately, and, moreover, the second can be tapered. This allows both the gain and the energy extraction to be optimized over a wide range of wavelengths. The realisation of the undulator consisted of several steps: mechanical construction, magnets sorting and magnetic field measurements with the associated computed trajectory and spontaneous emission spectrum for one electron through the field. In addition, two different beam diagnostics methods have been studied for insertion into the vacuum chamber of the undulator: a carbon wire (secondary emission) profile monitor, at each end of the undulator, and three optical transition radiation screens for the alignment of the electron and the optical beams respectively.

The purpose of CLIO (Collaboration pour un Laser Infra-rouge a Orsay) is to provide a tunable high-power infrared source in Orsay, at LURE. The permanent magnet undulator for the linear accelerator (linac) free electron laser is described here. This undulator consists of two independent parts of equal length and equal period, with independently adjustable magnetic gaps. Moreover, the second section can be tapered, to optimize both the gain and the energy extraction efficiency for a wide range of wavelengths. The realization of the undulator is described: mechanical system, the magnet sorting, measurements of the magnetic field for several cases of operation. The results of the modelling of the corresponding electron trajectory and spontaneous emission spectra are taken as tests of the quality of the undulator. Finally, the beam diagnostics associated with the undulator are presented: two secondary emission profile monitors and three optical transition radiation screens for electron and optical beam alignment.

The NA48 charged trigger is a mixed hardware and software real-time processing system intended to detect the interesting configurations of K0 charged decays. It achieves real-time event building, track reconstruction and kinematics computation on drift chamber data at an event rate of 100 kHz and within a maximum decision latency of 100 μ s. The system uses data driven, FPGA-based coordinate builders, a hardware event builder based on a crossbar switch, and a farm of up to 16 event processors for its software part. It has been installed and operated at CERN since 1995. After a description of the constraints and architecture of the various subsystems, the paper gives an account of the results and performance of the system based on the 1996/1997 runs. More specifically, the replacement of the present DSP-based implementation of the processing farm by RISC processors will be discussed.

The total cross section for the photoemission of fission fragments σ(γ, F) has been measured for 235U and 238U using tagged bremsstrahlung photons in the energy range 120–460 MeV. The fission fragments were detected in parallel plate avalanche detectors. The results are compared with other information on the photonuclear absorption cross section.

The CLIO collaboration has started in 1986 in order to build an infrared laser at LURE at Orsay. It includes the design and construction of a new FEL dedicated rf linear accelerator. The goal is to make a broadly tunable laser (at least in the range 2–20 μm), of high peak power (MW range), and “medium” average power (a few tens of watts). It will be utilized as a “user facility” as well as for FEL fundamental studies. The linac uses a gridded disperser cathode gun, a 500 MHz prebuncher, a fundamental buncher and one accelerating section powered by a 3 GHz klystron (with 12 μs long pulses). The final energy will be adjustable between 30 and 75 MeV. The desired characteristics are: peak current >50 A, total energy spread ≈1%, normalized emittance

The absolute photofission cross sections for 232 Th and 235, 238 U has been studied from 20 to 110 MeV using the photon tagging technique at the Saclay linear electron accelerator (ALS). The fission fragments were directly detected using a parallel plate avalanche detector (PPAD). The basic experimental results are a set of data giving σ ( E γ , fission). These results are compared with the few other measurements performed with monochromatic photons. From a comparison of the present fission data with the total absorption cross section, the total fission probability was deduced. The behaviour of this probability was discussed in terms of a cascade model for fission-evaporation competition. Quite good agreement is found with a calculation based on the hybrid model of pre-equilibrium reactions.

Absolute photofission cross sections of 235,238U have been measured in the energy range 40–105 MeV with “tagged” photons, using parallel plate avalanche counters for a direct detection of the fission fragments. The measured cross sections are nearly constant in the investigated energy range and amount to about 17 mb for both isotopes. The results are compared with recent photoneutron data.

The tagged photon technique has been used to measure the 6 Li photoproton cross sections over the energy range 40 E γ θ p Lab =90°. Comparison of the results with a quasi-deuteron calculation shows that photon interaction with proton-neutron pairs is dominant for high excitation energies in the residual nucleus and for E γ > 80 MeV.

A device to extract a parasitic beam from the main electron beam of the Saclay 600 MeV linac is described. Such a facility is completely transparent to the other users and preserves the original duty cycle. However the intensity of this beam is very low but sufficient to test and run some particular photonuclear experiments associated with the tagged photon facility. The main characteristics and a few applications of this parasitic beam are also given.