Linac4, a New Injector for the CERN PS Booster

The first bottle-neck towards higher beam brightness in the LHC injector chain is due to space charge induced tune spread at injection into the CERN PS Booster (PSB). A new injector called Linac4 is proposed to remove this limitation. Using RF cavities at 352 and 704 MHz, it will replace the present 50 MeV proton Linac2, and deliver a 160 MeV, 40 mA H- beam. The higher injection energy will reduce space charge effects by a factor of 2, and charge exchange will drastically reduce the beam losses at injection. Operation will be simplified and the beam brightness required for the LHC ultimate luminosity should be obtained at PS ejection. Moreover, for the needs of non-LHC physics experiments like ISOLDE, the number of protons per pulse from the PSB will increase by a significant factor. This new linac constitutes an essential component of any of the envisaged LHC upgrade scenarios. It is also designed to become the low energy part of a future 3.5 GeV, multi-megawatt superconducting linac (SPL). The present design has benefited from the support of the French CEA and IN2P3, of the European Union and of the ISTC (Moscow). The proposed machine and its layout on the CERN site are described

160 MeV H−H^- Injection into the CERN PSB

The H- beam from the proposed LINAC4 will be injected into the four existing rings of the PS Booster at 160 MeV. A substantial upgrade of the injection region is required, including the modification of the beam distribution system and the construction of a new H- injection system. This paper discusses beam dynamics and hardware requirements and presents the results of optimisation studies of the injection process for different beam characteristics and scenarios. The resulting conceptual design of the injection region is presented, together with the main hardware modifications and performance specifications

Construction Status of Linac4

The civil engineering works of the Linac4 linear accelerator at CERN started in October 2008 and regular machine operation is foreseen for 2013. Linac4 will accelerate H−ions to an energy of 160 MeV for injection into the PS Booster (PSB). It will thus replace the ageing Linac2, which presently injects at 50 MeV into the PSB, and it will also represents the first step in the injector upgrade for the LHC aiming at increasing its luminosity. This paper reports on the status of the design and construction of the main machine elements, which will be installed in the linac tunnel from the beginning of 2012 onwards, on the progress of the civil engineering and on the ongoing activities at the Linac4 test stand

Progress in the Design of the SPL, an H−H ^{-} High-Intensity Linac at CERN

The SPL (Superconducting Proton Linac) is a 4 MW 2.2 GeV H- linac, intended to re-use most of the 352 MHz RF equipment from the decommissioned LEP machine. Injecting into the CERN PS, this linac would improve the intensity and quality of the CERN proton beams, while as a stand-alone facility could provide intense beams of radioactive ions or neutrinos (Neutrino Superbeam). Together with accumulator and compressor rings, it would be a suitable driver for a Neutrino Factory. Since the original proposal, many improvements to the design have been introduced, in order to simplify the layout and reduce costs. They include the reduction of the repetition frequency to 50 Hz, the design of a shorter superconducting (SC) linac section that goes up to the full energy with b=0.8 cavities, an improved DTL section including a new CCDTL design, a chopping line based on fast (2 ns rise time) low-voltage choppers and pulser, and a simplified front-end. Moreover, the problem of pulse mode operation of a superconducting linac with more than one cavity per klystron has been analysed in more detail, showing additional limitation but also proposing some possible compensation schemes

Summary of Simulation Results for a Muon Cooling Experiment based on the 88 MHz CERN Cooling Channel

We present a summary of simulation results on a muon cooling experiment based on 88MHz cavities. The systems studied are subsections of the cooling channel in the CERN reference scheme for a neutrino factory. We present two different set-ups using 8 and 4 cavities. For each of these channels we have carried out a beam dynamics study based on engineering designs for the cavities and solenoids. The study comprises a scan of input beam parameters, various optics with and without alternating solenoid polarity as well as a cross-check with an independent simulation code

Conceptual design of the SPL II: A high-power superconducting H−H^- linac at CERN

An analysis of the revised physics needs and recent progress in the technology of superconducting RF cavities have led to major changes in the speci cation and in the design for a Superconducting Proton Linac (SPL) at CERN. Compared with the rst conceptual design report (CERN 2000012) the beam energy is almost doubled (3.5 GeV instead of 2.2 GeV), while the length of the linac is reduced by 40% and the repetition rate is reduced to 50 Hz. The basic beam power is at a level of 45MW and the approach chosen offers enough margins for upgrades. With this high beam power, the SPL can be the proton driver for an ISOL-type radioactive ion beam facility of the next generation (`EURISOL'), and for a neutrino facility based on superbeam C beta-beam or on muon decay in a storage ring (`neutrino factory'). The SPL can also replace the Linac2 and PS Booster in the low-energy part of the CERN proton accelerator complex, improving signi cantly the beam performance in terms of brightness and intensity for the bene t of all users including the LHC and its luminosity upgrade. Decommissioned LEP klystrons and RF equipment are used to provide RF power at a frequency of 352.2 MHz in the lowenergy part of the accelerator. Beyond 90 MeV, the RF frequency is doubled to take advantage of more compact normal-conducting accelerating structures up to an energy of 180 MeV. From there, state-ofthe- art, high-gradient, bulk-niobium superconducting cavities accelerate the beam up to its nal energy of 3.5 GeV. The overall design approach is presented, together with the progress that has been achieved since the publication of the rst conceptual design report

The SPL (II) at CERN, a Superconducting 3.5 GeV H- Linac

A revision of the physics needs and recent progress in the technology of superconducting (SC) RF cavities have triggered major changes in the design of a SC H-linac at CERN. With up to 5MW beam power, the SPL can be the proton driver for a next generation ISOL-type radioactive beam facility (âEURISOLâ) and/or supply protons to a neutrino () facility (conventional superbeam + beta-beam or -factory). Furthermore the SPL can replace Linac2 and the PS booster (PSB), improving significantly the beam performance in terms of brightness, intensity, and reliability for the benefit of all proton users at CERN, including LHC and its luminosity upgrade. Compared with the first conceptual design, the beam energy is almost doubled (3.5GeV instead of 2.2 GeV) while the length is reduced by 40%. At a repetition rate of 50 Hz, the linac reuses decommissioned 352.2MHz RF equipment from LEP in the low-energy part. Beyond 90MeV the RF frequency is doubled, and from 180MeV onwards high-gradient SC bulkniobium cavities accelerate the beam to its final energy of 3.5GeV. This paper presents the overall design approach, together with the technical progress since the first conceptual design in 2000