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A small quadrupole mass analyser was used to measure the residual gases in a stainless steel ultra-high vacuum system (vacuum baked at 150°C for 10 days) of 7500 l volume, pumped by a NEG pump (nominal 100 l s −1 ). A series of experiments is described which shows that the indicated partial pressures of all of the residual gases, except hydrogen, are increased due to their production in the analyser. It has not been possible to accurately quantify the effect, but upper limits for the specific outgassing rates (mbar l s −1 cm −2 ) are : 2 × 10 −13 for hydrogen, ⩽1 × 10 −18 for methane, ⩽3 × 10 −17 for water, ⩽4 × 10 −16 for carbon monoxide and ⩽2 × 10 −17 for carbon dioxide.

MERIT is a proof‐of‐principle experiment of a target station suitable as source for future muon colliders or neutrino factories. When installed at the CERN (European Organization for Nuclear Research) PS (Proton Synchrotron) complex fast‐extracted high‐intensity proton beams intercepted a free mercury jet inside a normal‐conducting, pulsed 15‐T capture solenoid magnet cooled with liquid nitrogen. Up to 25 MJ of Joule heat was dissipated in the magnet during a pulse. The fully automated, remotely controlled cryogenic system of novel design permitted the transfer of nitrogen by the sole means of differential pressures inside the vessels. This fast cycling system permitted several hundred tests in less than three weeks during the 2007 data taking campaign.

A discussion is given of the advantages of thin-walled convoluted vacuum tubes for the long arms of interferometric gravitational wave detectors currently being proposed by a number of institutions around the world. Typically the tubes will be 3 km long and 1.5 m in diameter. Pressures of ⩽ 10 −7 mbar are required for hydrogen and at least an order of magnitude lower for the sum of all the other gases. The results of tests of some of the mechanical and vacuum properties of a prototype section of convoluted tube are presented. The tube is 5 m long, 1.4 m internal diameter and is constructed from 0.91 mm thick 316L stainless steel sheet. The convolutions have a semicircular form of 20 mm radius, giving the tube a strength equivalent to a plain tube of the same diameter but 13 mm wall thickness. A specific outgassing rate of ∼3x10 −13 mbar I s −1 cm −2 is achieved by a vaccum bake at 150°C. Examination of the residual mass spectra reveals that > 99% of the gas is hydrogen.

Developments in the design of the vacuum system for the proposed gravitational wave detector, GEO, are described, together with some small scale tests. The vacuum chamber will consist of two horizontal stainless steel tubes, 1.4 m diameter and 3 km long, arranged in an L, connecting a number of experimental tank stations. By heating the tubes to 200°C in air, followed by a vacuum bake at 150°C, an outgassing rate of ∼ 10 −13 mbar l s −1 cm −2 will be achieved. Turbomolecular and non-evaporable getter pumps have been chosen to minimise pressure fluctuations and provide a hydrocarbon-free vacuum of ≤10 −8 mbar.

The development of the RIST tantalum foil target for the production of radioactive nuclei by bombardment with energetic (∼1 GeV) proton beams of high intensity (100 μA) has shown that targets capable of dissipating 20–60 kW of thermal power can be constructed. Tantalum is a good material for high power dissipation because, as a metal, it has a relatively good thermal conduction and is able to stand very high temperatures. However, for a full range of unstable beams, it will be necessary to have targets made from many different materials. Developments of high power target and ion source designs are discussed with particular emphasis on non-metallic, non-refractory powder and liquid target materials. Also, the possibilities of combining targets and ion sources to reduce effusion times are considered, as well as methods to increase the surface-desorption rates of the radioactive particles.

We describe an experiment designed as a proof-of-principle test for a target system capable of converting a 4-MW proton beam into a high-intensity muon beam suitable for incorporation into either a neutrino factory complex or a muon collider. The target system is based on exposing a free mercury jet to an intense proton beam in the presence of a high-strength solenoidal magnetic field.

A rotating toroid is considered as a target for the production of pions by intense high energy proton beams for a neutrino factory. The toroid rotates in vacuum and the power is radiated to the water-cooled walls of the vacuum chamber. It is shown that steady powers of over 100 MW can be dissipated by thermal radiation at temperatures of ∼2500 K, using a suitable refractory material such as tantalum or tungsten. Under pulsed beam conditions, the thermal stresses induced in the toroid will reduce the power capabilities.

Both diffusion and effusion in radioactive ion beam foil targets can be described mathematically by Fick’s Law of diffusion. An approximate solution to the equation with the appropriate boundary conditions is presented for the RIST geometry target. This solution is expressed in terms of the physical and geometrical properties of the target and ioniser: the diffusion constant of the foil material, the conductance and the dimensions of the target and ioniser. The results of fitting the equation to measured data are shown. The equation can be used to optimize the design of targets for different radioactive ion beams.

A description is given of the radioactive ion beam facility, SIRIUS, proposed to be built at ISIS, the world leading pulsed neutron source. Up to 100 μA of 800 MeV protons from the ISIS synchrotron will be taken down a new beam line into a target station complex where radioactive nuclei will be formed as a result of the interaction with the target. The nuclei are subsequently ionised and accelerated to 200 kV. The beam passes through a broad range spectrometer to provide several beams of different ion species simultaneously. One beam passes through a high resolution spectrometer and is accelerated in an RFQ and a superconducting linear accelerator to 10 MeV/amu, for nuclear physics research. The other beams are taken to a low energy experimental area.

Since the move of ISOLDE from CERN’s synchrocyclotron (SC) to the Proton Synchrotron Booster (PSB) in 1992 extensive work has been devoted to the development of new beams, i.e. the production of new isotopes, beams of higher intensity and the ionization of further elements. Most of these developments were driven by the particular needs of the physics community proposing new experiments. The main achievements were the adaption of liquid metal targets to the pulsed proton beam to prevent shockwaves and splashing inside the target container and systematic studies on the time structure of the release of the isotopes from the target. Furthermore the work on laser ion-sources already started at ISOLDE-2 was continued, the so-called RIST target was developed, and most recently first tests on the isotope production while increasing the proton energy from 1 GeV to 1.4 GeV were done. The latter topics are discussed in this paper.

A description is given of the vacuum system for a 1×1 km long optical interferometric gravitational wave detector. The vacuum chamber consists of two tubes, 900‐mm diameter, 1 km long, joined together in the shape of an L. End tanks ∼3‐m diameter ∼3 m long contain the optical equipment. The tubes will be heated to 150 °C to reach outgassing rates of ∼10−12 Torr l/s/cm2 and pumped by turbomolecular pumps at 500‐m intervals to obtain a pressure of ∼10−8 Torr. A significant cost saving is achieved by using thin‐walled corrugated stainless‐steel tube. The sensitivity of the detector is governed, among other things, by fluctuation in the vacuum pressure. Some discussion of the possible causes of these fluctuations is given.

A description is given of a small heavy‐ion linear accelerator based on the use of a twin transmission line as first suggested by Sloan and Lawrence. Ions are accepted if their e/m values are ⅛ or greater (relative to the proton) and are accelerated to a final energy of 1.04 Mev/nucleon. The accelerator has 40 drift tubes fitted with focusing grids, and about 350 kw of pulsed rf are needed for ions of e/m=⅛. The radio frequency is 25 Mc, and the accelerator is pulsed at up to 50 pps with a pulse length of 500 μsec. Injection velocity is 0.007 c, corresponding to a dc acceleration from the ion source through 180 kv for an ion of e/m=⅛. Ions are produced in a pulsed dc arc of the Penning type operating in a magnetic field of 1000 gauss and the dc accelerating voltage is supplied by an electrostatic generator. Typical pulsed meter currents so far obtained are, for He+, input 4 ma, output 150 μa; for N2+, input 3 ma, output 75 μa. The accelerator is the first stage of three which will take the ions to a final...

A review is given of the performance and characteristics of the various types of PIG sources used for the production of multiply charged ions. They are able to produce ions with a high charge to mass ratio for the lighter elements up to about neon, but for heavier elements the ratio fallssteadily. Charge states do not exceed 8 to 10 for argon and 12 for xenon. Although the development of the multiply charged PIG source, since its original inception, has been very slight, it is still the most powerful practical design in existence atl this time. A brief description of the general characteristics and the mechanisms involved in the PIG discharge are given , including a discussion of multiply charged ion production.

A review is given of existing sources of highly charged heavy ions. The performance of the sources, predominantly of the P.I.G. type, are summarized and compared. Some mechanisms for the production of high charge states are described. There is a brief description of new developments, particularly of devices using ion trapping.

Alumina vacuum chambers are being constructed for the rapid cycling synchrotron of the Spallation Neutron Source (SNS). The ceramic sections are butt jointed with a thin layer of glass to give strong, vacuum tight assemblies. This method of construction is considerably less expensive than metalized ceramic to metal jointed assemblies. A description is given of the principal ceramic chambers.

An 800 MeV synchrotron is to be built at the Rutherford Laboratory to provide intense pulsed beams of thermal neutrons. Because of the radiation levels the vacuum system should be highly reliable and require little maintenance. Ion pumps will be used in an ultra-high vacuum system containing no organic material. Since the synchrotron is pulsed at 50 Hz ceramic chambers are to be used in the magnets to avoid excessive eddy current losses. The effect of intense proton beams on alumina is being studied and a method for bonding alumina sections together using glass is being tested.