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This paper describes the first results of a feasibility study undertaken at CERN to determine whether a laser-produced plasma can be used as a source of intense highly charged heavy ion beams. A variety of important measurements have been made, and the results are encouraging. Furthermore, a beam of highly charged light ions produced by the laser ion source has been accelerated successfully in a radio frequency quadrupole (RFQ) structure

A research program with the aim of producing pulsed currents with hitherto unequalled intensity of Pb27+, with length and repetition ratecompatible with those desired by CERN (1 mAe / 400 ms / 10 Hz in the context of future heavy ion collisions at LHC) is organised in acollaboration between CERN/GSI/CEA-Grenoble and IN2P3-ISNG.Two main experimental programs will be carried out : (i) tests with the LNS-Catania team on the SERSE superconducting source with a 28 GHzgyrotron, (ii) tests on a non-superconducting source (new source at Grenoble) with a 28 GHz gyrotron. For this purpose CEA/DRFMC hasborrowed from CEA a 28 GHz - 10 kW gyrotron transmitter.The project includes also the construction of a source body, by ISNG, with conventional coils and permanent magnets for working at the frequencyof about 28 GHz and biased up to 60 kV. This source called PHOENIX will run on a test bench at ISN. PHOENIX is an improvement of thepresent ECR4-14.5 GHz/CERN source, having a mirror ratio R=2 at 14.5 GHz, and R=1.7 at 28 GHz (possibly reaching 2.1 T on the axis of thesource), and with a plasma volume up to 2.5 larger.Experiments at 28 GHz will be performed on the SERSE source in Catania at INFN/LNS where both the axial and the hexapolar fields will bevaried so that the mirror ratio is continuously varied up to R=1.6 ; the SERSE source will be also operated at lower magnetic fields such as thosewhich can be produced by conventional magnets (less than 2 T axial field at injection - far from the 28 GHz High-B mode).

The workshop ‘Physics with a multi-Megawatt (MMW) Proton Source' was held at CERN on 25-27 May 2004. It was organized by the ECFA/BENE working groups for future neutrino facilities in Europe and by the EURISOL nuclear physics community to explore the physics opportunities offered by a new high intensity proton accelerator. It confirmed the important synergies that exist between these communities. This document summarises the main design choices for the accelerators and experiments involved, the physics possibilities and the most critical R&D that will be necessary. A preliminary baseline road map is delineated

The articles contained in this volume represent the work performed in the years 2000-2003 on the ECFA sponsored study of a 'European Neutrino Factory Complex'. Future neutrino facilities for Europe invariably encompass a high-intensity proton driver. They can develop progressively, starting from a low-energy neutrino superbeam, via beta beams, to a neutrino factory and muon colliders based on muon storage rings. The ambitious and broad physics programme ranges from cutting-edge nuclear physics and muon physics to leptonic CP violation. The accelerator complex, neutrino oscillation experiments, precision study of neutrino interactions, low-energy muon experiments, kaon physics and muon collider physics are described in tum.

The Neutrino Factory is a new concept for an accelerator that produces a high-intensity, high-energy beam of electron and muon neutrinos - the ultimate tool for neutrino oscillation studies and the only machine conceived up today that could help detect CP violation of leptons. The basic concept of the Neutrino Factory is the production of neutrinos from the decay of high-energy muons. Due to their short lifetime, these muons have to be accelerated very fast. Several new accelerator techniques, like a high-intenstiy proton linac, high-power targets, ionization cooling or recirculating muon linacs are required. This paper presents a snapshot of the accelerator design at CERN. Although some aspects of this European Neutrino Factory Scheme have been optimised for the CERN site, the basic principle is site-independent.

A Neutrino Factory based on a muon storage ring is perhaps the ultimate tool for studies of neutrino oscillations and possibly of leptonic CP violation and may open the way to muon colliders. Linear accelerators and their technologies are likely to play a dominant role in the complex of a Neutrino Factory. An overview of different scenarios worked on in the US, Japan and Europe will be presented. The basic layout of a Neutrino Factory consists of a high power proton driver, a high power target where pions are produced, which decay rapidly into muons. These muons are accelerated and fed into a storage ring producing a well-collimated neutrino beam by their decay. Emittance reduction ("cooling") of the muon beam is an important issue. A cooling experiment is therefore planned and some details will be discussed. Other ways for producing neutrino beams ("Super beams" and "Beta beams") will be briefly indicated.

Recently, a series of meetings were organised with PS and SPS participants, to discuss the possibilities of increasing the proton intensity on the SPS targets (with particular emphasis to CNGS) as well as ISOLDE and nTOF. Increasing the brilliance of the LHC beam, as required for ultimate LHC performance, was also discussed. Several schemes were proposed, as a staged approach, i.e. starting from the most simple and cheap, though difficult, to the more advanced and expensive. After comparing the advantages and disadvantages of the various methods, three basic schemes were retained as candidates for further investigations and as good / necessary starting points for further improvements. Chapter 1 is devoted to PSB and PS issues and contains essentially a description of the three selected schemes. Chapter 2 deals with limitations in the SPS. Chapter 3 is a synthesis of basic conclusions. In the Appendix, a work-plan is presented for PSB and PS theoretical and experimental studies with a time estimate for preliminary results.

There is a strong interest from the physics community for high-quality, high-intensity neutrino beams as produced by a neutrino factory. With the help of other European laboratories, CERN has started a study on some of the many technological challenges of such a facility. Present ideas concerning the proton driver, as well as the muon accelerator complex, are presented and plans for the future are described.

The paper describes the CERN approach for a proton driver for a Neutrino Factory. Two main layouts are presented: the so-called CERN Reference Scenario, based on a 2.2 GeV linac and an alternative one, based on a 30 GeV synchrotron. Both produce bunches of 1 ns (r.m.s.) and a beam power of 4 MW.

An 8 Hz proton driver for a neutrino factory of 4 MW beam power and an energy of 25-30 GeV is under study at CERN, in parallel with a similar investigation using a 2.2 GeV high-energy linac and an accumulator plus a compressor ring cycling at 75 Hz. At RAL, synchrotron drivers with final energies of 5 and 15 GeV cycling at 50 and 25 Hz, respectively, are being studied. With these four scenarios, one hopes to cope with all possible constraints emerging from the studies of the pion production target and the muon rotation and cooling system. The high beam energy of this scenario requires less proton current and could inject into the SPS above transition and upgrade LHC and fixed target physics. Its 440 kW booster would upgrade ISOLDE.The main problems of the driver synchrotron are: the requirement of about 4 MV RF voltage at 10 MHz for acceleration and adiabatic bunch compression to the required r.m.s length of 1 ns; the sensitivity of the compression to the impedance of the vacuum chamber and to non-linearities of the momentum compaction of the high-gt lattice.

The proton driver for a neutrino factory must provide megawatts of beam power at a few GeV, with nonosecond long bunches each containing more than 1x1012 protons. Such beam powers are within reach of a high-energy linac, but the required time structure cannot be provided without accumulation and compression. The option of a linac-based 2.2 GeV proton driver has been studied at CERN, taking into account the space charge and stability problems which make beam accumulation and bunch compression difficult at such a low-energy. A solution featuring two rings of approximately 1 km circumference has been worked out and is described in this paper. The subjects deserving further investigation are outlined.

A research program with the aim of producing pulsed currents with hitherto unequalled intensity of Pb27+, with length and repetition ratecompatible with those desired by CERN (1 mAe / 400 ms / 10 Hz in the context of future heavy ion collisions at LHC) is organised in acollaboration between CERN/GSI/CEA-Grenoble and IN2P3-ISNG.Two main experimental programs will be carried out : (i) tests with the LNS-Catania team on the SERSE superconducting source with a 28 GHzgyrotron, (ii) tests on a non-superconducting source (new source at Grenoble) with a 28 GHz gyrotron. For this purpose CEA/DRFMC hasborrowed from CEA a 28 GHz - 10 kW gyrotron transmitter.The project includes also the construction of a source body, by ISNG, with conventional coils and permanent magnets for working at the frequencyof about 28 GHz and biased up to 60 kV. This source called PHOENIX will run on a test bench at ISN. PHOENIX is an improvement of thepresent ECR4-14.5 GHz/CERN source, having a mirror ratio R=2 at 14.5 GHz, and R=1.7 at 28 GHz (possibly reaching 2.1 T on the axis of thesource), and with a plasma volume up to 2.5 larger.Experiments at 28 GHz will be performed on the SERSE source in Catania at INFN/LNS where both the axial and the hexapolar fields will bevaried so that the mirror ratio is continuously varied up to R=1.6 ; the SERSE source will be also operated at lower magnetic fields such as thosewhich can be produced by conventional magnets (less than 2 T axial field at injection - far from the 28 GHz High-B mode).

A proposal was made at the end of 1996 to use the large inventory of RF hardware available after the decommissioning of LEP-2 for the construction of a 2 GeV Superconducting Proton Linac (SPL) to inject directly into the PS [1.1]. The brightness of the beam in the PS at low energy would double, helping the injector complex to satisfy the requirements of the LHC and benefiting the planned proton physics programme. Additional users could also be accommodated thanks to the capability of the SPL to operate at a much larger duty factor than that required for high-energy physics. Consequently, a small study group has been set up to analyse the major technical aspects of the SPL design as well as the processes of injection and capture in the PS. This report summarises the work done so far, and provides some information about the other possible uses of the SPL beam. The feasibility of such a cascade of accelerators is confirmed, although an in-depth design study is still required before the realistic performance and detailed design of that facility can be announced.

This preliminary feasibility study is based on the availability of the CERN LEP2 superconducting RF system after LEP de-commissioning. The option that is explored is to use this system as part of a high energy H- linac injecting at 2 GeV into the CERN PS, with the aim of reliably providing at its output twice the presently foreseen transverse beam brightness at the ultimate intensity envisaged for LHC. This requires the linac to be pulsed at the PS repetition rate of 0.8 Hz with a mean beam current of 10 mA which is sufficient for filling the PS in 240 ms (i.e. about 100 turns) with the ultimate intensity foreseen for injection for the LHC. The linac is composed of two RFQs with a chopping section, a room temperature DTL, a superconducting section with reduced beta cavities up to 1 GeV, and a section of LEP2 cavities up to 2 GeV. This study deals, in particular, with the problems inherent in H- acceleration up to high energy and in the pulsed operation of SC cavities. Means for compensating microphonic vibrations in the SC cavities are considered, with the aim of reducing the final overall energy spread to the tight requirements for injection into a synchrotron. Other possible applications of such a machine are also briefly reviewed, that make use of its potential for working at a higher duty cycle than required for LHC alone.

For the CERN Lead Ion Accelerating Facility (achieved within a collaboration of several outside laboratories and with financial help of some member states) a new dedicated Linac has been built. This Linac has been installed in 1994 and served during two extended physics runs. This paper reviews the main characteristics of this machine and describes the first operational experience. Emphasis is put on new features of this accelerator, its associated equipment and on the peculiarities of heavy ions.

A Three Dimensional Bunch Shape Monitor (3D-BSM) has been developed for the CERN Proton Linac 2. A new area for beam studies at high intensities has been opened by this detector. Bunch density distributions in all three dimensions and their variations along the beam pulse can be obtained. Changing field gradients in linac quadrupoles, emittance variation along the bunch has been calculated. Measurements of beam halos become possible thanks to the large dynamic range of the device. Beam parameters at various linac settings have been measured and analysed.

The relatively low duty cycle of pulsed accelerators can give rise to problems in matching the characteristics of multi-charged ion sources to the beam intensity required by the user. Heavy ion physics interests, especially in the heavy ion colliders, demand more and more intensity whilst the accelerator designers require higher charge states to ease their machine problems. Various options for ion sources for present and future heavy ion accelerators are presented.

A new library of the computer codes for the mathematical simulation of heavy ion production in the ECR ion source is presented. These codes are based on the equations of model of ion confinement and losses in ECR ion sources. The ECR4 developed at GANIL is now used for lead ion production for the accelerator complex at CERN. An ion pulse with a current of up to 100 emA of Pb27+ has been regularly injected into the linac since May 1994. The results of numerical simulation with these computer codes and interpretation of experimental data of lead ion production in the ECR source at CERN are presented.

In fall 1994 the new heavy ion injector at CERN was brought into operation successfully and a lead beam of 2.9´107 ions per pulse was accelerated in the SPS up to an energy of 157 GeV/u. The ion source, which was supplied by GANIL (France) was in operation almost continuously over a period of about one year and proved to be very reliable. It pro-duces a current of more than 100 µA of Pb27+ (after the first spectrometer) during the afterglow of the pulsed discharge. The current stays within 5% of the maximum value for a time of about 1 ms, which is more than required by the accel-erators. Measurements of the charge state distribution, emittance and energy spread, which were made during this window, are presented together with other operating data.