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The project "Dubna Electron Synchrotron" (DELSY) is aimed to construct a synchrotron radiation source of the 3d generation at the Joint Institute for Nuclear Research. The DELSY synchrotron radiation source will be constructed on the base of the accelerator facility of the Institute for Nuclear Physics and High Energy Physics (NIKHEF), Amsterdam, the Netherlands. This accelerator facility consists of a linear electron accelerator MEA (Medium Energy Accelerator) for the electron energy of 700 MeV and the electron storage ring AmPS (Amsterdam Pulse Stretcher) for the maximum electron energy of 900 MeV at the circulating beam current of 200 mA. The DELSY storage ring is supposed to be constructed with the use of the "Amsterdam Pulse Stretcher" (AmPS) [1] storage ring the focusing system of which will be essentially modified: the ring circumference will be approximately 1.5 times smaller, the electron energy will be increased up to 1.2 GeV and the focusing strength will be enhanced. These measures will allow obtaining the beam emittance at least ten times smaller which subsequently increases the synchrotron radiation brilliance by several orders of magnitude. The rigging of the DELSY ring with the insertion devices — the superconducting wiggler with the magnetic field of 10 T and the so-called "vacuum hybrid miniundulator" is the principle feature of the new synchrotron radiation source. Both devices developed by Budker INP, Novosibirsk, will allow to enrich the DELSY characteristics as the synchrotron radiation source expanding its radiation spectrum in the region of the hard X-rays and increasing its brilliance up to 3 ⋅10 18

To obtain high-duty (90%) electron beams, the present 2%-d.f., 500-MeV linac (MEA) will be modified into a low-d.f. (0.1%) injector for the pulse stretcher ring presently under construction. The accelerator peak current has to be increased from 10 mA to 80 mA to obtain an average current of 65 mu A from the pulse stretcher. The resulting increase of the energy spread from 0.3% to 1-2% requires the installation of an energy compression system (ESC) to match the 0.2% acceptance of the pulse stretcher. The ESC consists of four magnets followed by a short-filling time RF traveling wave accelerator structure. Considerations concerning required energy range, beam loading, phase errors, and current ripple which determine the longitude dispersion and the required RF power source are presented. >

To obtain electron beams with a high duty factor, a stretcher and storage ring will be added to the existing Medium Energy Accelerator (MEA) facility. The ring will operate at energies between 250 and 900 MeV and with circulating currents up to 200 mA. The storage mode will be used for internal target physics. Discussed in detail are the basic ring design; the ring hardware; linac modifications; and time schedule, manpower, and budget. >

AmPS has been built to enhance substantially the main specifications of the 1% duty factor 550 MeV electron accelerator facility MEA. The maximum energy will be raised to 0.9 GeV while the duty factor increases from 1% to approximately 100%. To this purpose the ring AmPS was added to the facility. Simultaneously the linac was upgraded both in current and energy. Two modes of operation for the ring are implemented: a Pulse Stretcher mode with 3 turn injection creating an external beam, and a Storage Mode with multi turn injection for internal target physics. The commissioning of the ring started in April 1992. Within two months 10% duty factor beams could be delivered for electron scattering experiments. Meanwhile the performance of the machine has been improved dramatically. The actual performance of the ring is presented and is compared with the initial design goals. >

The operating RF frequency of the AmPS stretcher ring is 2856 MHz. The beam pipe cross section is above cut-off for some modes of this frequency. This inhibits proper functioning of the stripline beam position monitors. The problem has been solved by applying particularly shaped high vacuum quality RF dampers. >

The AmPS (Amsterdam Pulse Stretcher) is a 900-MeV electron storage and stretcher ring. Its construction started early 1991. A fast-response, high-resolution stripline-type beam position monitor has been developed for the ring. The monitor has a quasi-elliptic cross section. Its sensing strips have a length of lambda /4; the operating frequency is 2856 MHz. The mechanical construction, the matching of the output ports, and the online calibration system are described. The results of bench measurements as well as measurements with a 500-MeV beam are also presented. >

AmPS is a 300-900 MeV electron ring. The machine was designed as a pulse stretcher to provide continuous external beams. After years of successful operation in this mode the nuclear physics program now concentrates on experiments with stored beams interacting with internal gas targets. These experiments require currents between 50 and 200 mA through 60 cm long 15 mm wide cylindrical target cells. Gas pressures in the open-ended cells correspond to target thickness of 10/sup 14/ to 10/sup 16/ atoms/cm/sup 2/. Strong stray fields from a spectrometer and from target holding fields disturb the closed orbit. Under operational conditions the linac provides a maximum energy of 700 MeV, so ramping is required to achieve 900 MeV. To further increase the luminosity at the target a reduced emittance lattice based on the existing magnet configuration has been designed. Late 1996 a polarized electron injector as well as a "Siberian Snake" to control the spin on the internal target became operational. The polarized injector delivers a few mA to the linac so stacked injection in the ring is required. With strained InGaAsP cathodes a polarization of 80% was obtained. Test results, performance and prospects are presented.

AmPS is an electron storage and pulse stretcher ring operating between 300 and 900 MeV with stored beam currents up to 200 mA. For beam diagnostics the AmPS ring has been provided with 32 stripline beam position monitors, 17 low beam impedance designed screens, a DCCT and 4 synchrotron light ports. In addition 3 scanning wires for injection control, 32 air filled ionisation chambers for beam loss control, a kicker for tune measurements and a harmonic shaker have been implemented. The purpose, design and performance of these devices will be described. The data acquisition for closed orbit correction and tune measurement will be presented as well.

The Amsterdam Pulse Stretcher AmPS is a 300-900 MeV electron storage ring with a circumference of 212 m. The ring operates either in stretcher mode to provide external continuous beams of tens of /spl mu/A or in storage mode with currents up to 200 mA for internal target experiments. Machine commissioning and simultaneous operation started for nuclear physics started mid 1992. The actual performance is presented. During 1995 a polarized electron source will be added to the linac injector. A "Siberian Snake" acting as a spin flipper will be implemented in the ring; these systems have been made by the Institute for Semiconductor Physics at the Budker Institute of Nuclear Physics both at Novosibirsk as part of a scientific collaboration agreement. Results from a feasibility study on the use of the ring as a free electron laser in the VUV region are also summarized.

We report on first measurements with polarized electrons stored in a medium-energy ring and with a polarized internal target. Polarized electrons were injected at 442 MeV (653 MeV), and a partial (full) Siberian snake was employed to preserve the polarization. Longitudinal polarization at the interaction point and polarization lifetime of the stored electrons were determined with laser backscattering. Spin observables were measured for electrodisintegration of polarized He-3, with simultaneous detection of scattered electrons, protons, neutrons, deuterons, and He-3 nuclei, over a large phase space.

We report on the results of studies of the longitudinal electron polarization in the AmPS storage ring at NIKHEF. The ring was operated using a partial Siberian snake at the first magic energy, and a full Siberian snake between 440 MeV and 720 MeV. We have investigated the effect of high beam currents in the ring, and found that some of the electron polarization is lost if the beam current becomes larger than ≈120 mA.

An electron-scattering facility is describes that received low-energy electron beams with E0 ≦ 140 MeV from the 500 MeV medium energy accelerator. It is equipped with a 180° scattering system with a relatively large solid angle (2.9 msr) and a broad momentum acceptance. Electrons scattered between 177° and 183° can be detected with a 19-channel overlapping-scintillator system placed in the focal plane of a magic-angle spectrometer. Various test results are shown to demonstrate the performance of the system.

The 85 MeV electron linac of the Institute for Nuclear Physics Research in Amsterdam (EVA) is now fully operational. At high energies and low currents, 80% of the current of the low-emittance beam falls within a 0.3% energy-base. Maximum peak currents of up to 150 mA within a 0.8% energy-band are obtainable regularly. This performance is attained using two SLAC sections (each 3 m long), and a Frascati-type injector. The inherent properties of both are matched by the performance of the peripheral equipment which includes two klystron modulators, the cooling system, the microwave driver and interface instrumentation.

In order to increase the duty factor (d.f.) of the present 500 MeV electron linac from 2.5 % to > 90 %, it is proposed to add a pulse stretcher to the facility. By replacing 4 of the 12 existing 4 MW klystrons by 25 MW types, the injection energy will be increased to E = 700 MeV. A peak current of 40 mA will be injected during three turns with 365 pps. to yield an extracted beam current of 40 ?A. The machine operates near a third order resonance. The chromaticity is non-zero. Extraction proceeds by changing the cavity frequency (2856 MHz); this will push the beam into the unstable region of the phase space. An energy compressor will reduce the momentum spread of the injected beam to ?dp/p? = 0.1 %.