High Intensity Proton Source Research Articles

High intensity proton source based on a hollow-cathode reflex discharge.

We describe here the electrode system, design, and parameters of an ion source based on a Penning-type hollow-cathode reflex discharge developed for generation of proton beams. Especially for proton beam generation, a modified geometry of both hollow and reflex cathodes was fabricated. The working gas is molecular hydrogen. Ion extraction and beam formation are performed using a three-electrode single-aperture optical system with a 3-mm diameter emission aperture. At an accelerating voltage of 33-35kV and a discharge current of 0.55A in continuous mode, the ion beam current was 15-17 mA, and in pulsed mode, at a discharge current of about 2A, the beam current was 55 mA. The beam consists mainly of H+, H2+, and H3+ ions, with the proton (H+) fraction up to 27% in continuous mode and 40% in pulsed mode.

Improvement of the characterization of the proton source for the European Spallation Source by means of optical emission spectroscopy

At the Istituto Nazionale di Fisica Nucleare--Laboratori Nazionali del Sud (INFN-LNS), the commissioning of the high intensity proton source for the European Spallation Source (PS-ESS) has been recently completed. Optical emission spectroscopy measurements carried out with PS-ESS permitted, in a noninvasive way, the evaluation of the electron density, temperature, and relative abundances of the neutral components of a hydrogen plasma. This approach is helpful in finding the optimal source parameters exploiting protons or ${H}_{2}^{+}$ beams production.

Experimental performance of the chopper for the ESS LINAC

At the Istituto Nazionale di Fisica Nucleare – Laboratori Nazionali del Sud (INFN-LNS) the beam commissioning of the high intensity Proton Source for the European Spallation Source (PS-ESS) was completed in November 2017. The ESS requires a high intensity proton beam (74mA pulsed at 14 Hz of repetition rate), with fast Beam pulse rise/fall time (< 20 μs). In order to meet the project requirement, an electrostatic chopping system has been used in the Low Energy Beam Transport (LEBT). The design of the control system was done also to be the main element of the fast beam abort system and taking into account the radiation issue in the accelerator tunnel. This paper describes the performances of the chopper. The experimentally-achieved rise/fall times of the beam pulses measured by using an AC Current Transformer (ACCT) at the end of the LEBT collimator, are presented. An experimental investigation of the effects of different amounts and types of gas injected into the LEBT (for the sake of space charge compensation) has been carried out with respect to the beam and chopper parameters.

Beam commission of the high intensity proton source developed at INFN-LNS for the European Spallation Source

At the Istituto Nazionale di Fisica Nucleare - Laboratori Nazionali del Sud (INFN-LNS) the beam commissioning of the high intensity Proton Source for the European Spallation Source (PS-ESS) started in November 2016. Beam stability at high current intensity is one of the most important parameter for the first steps of the ongoing commissioning. Promising results were obtained since the first source start with a 6 mm diameter extraction hole. The increase of the extraction hole to 8 mm allowed improving PS-ESS performances and obtaining the values required by the ESS accelerator. In this work, extracted beam current characteristics together with Doppler shift and emittance measurements are presented, as well as the description of the next phases before the installation at ESS in Lund.

ORKA: The Golden Kaon Experiment

ORKA is a proposed experiment to measure the K+→μ+νν¯ branching ratio with 5% precision using the Fermilab Main Injector high intensity proton source. The detector design is based on the BNL E787/E949 experiments, which detected seven K+→μ+νν¯ candidate events. Two orders of magnitude improvement in sensitivity relative to the BNL experiments comes from enhancements to the beam line and the detector acceptance. Precise measurement of the K+→μ+νν¯ branching ratio with the same level of uncertainty as the well-understood Standard Model prediction allows for sensitivity to new physics at and beyond the LHC mass scale.

The Fermilab Project-X Research Program

Fermilab has been working with the international particle physics and nuclear physics communities to explore and develop research programs possible with a new high intensity proton source known as “Project-X”. Project X will provide multi-megawatt proton beams from the Fermilab Main Injector over the energy range 60-120 GeV, simultaneous with multi-megawatt protons beams at 3 GeV with very flexible beam-timing characteristics. The Project-X research program includes world leading sensitivity in long-baseline neutrino experiments, neutrino scattering experiments, a rich program of ultra-rare muon and kaon decays, opportunities for nextgeneration electric dipole moment experiments and other nuclear/particle physics probes that reach far beyond the Standard Model of particle physics. The sensitivity and future prospects of these lines of research are discussed.

The acceleration and storage of radioactive ions for a beta-beam facility

The term beta-beam has been coined for the production of a pure beam of electron neutrinos or their antiparticles through the decay of radioactive ions circulating in a storage ring. This concept requires radioactive ions to be accelerated to as high Lorentz gamma as 150. The neutrino source itself consists of a storage ring for this energy range, with long straight sections in line with the experiment(s). Such a decay ring does not exist at CERN today, nor does a high-intensity proton source for the production of the radioactive ions. Nevertheless, the existing CERN accelerator infrastructure could be used as this would still represent an important saving for a beta-beam facility.

The acceleration and storage of radioactive ions for a neutrino factory

The term beta-beam has been coined for the production of a pure beam of electron neutrinos or their antiparticles through the decay of radioactive ions circulating in a storage ring. This concept requires radioactive ions to be accelerated to a Lorentz gamma of 150 for 6He and 60 for 18Ne. The neutrino source itself consists of a storage ring for this energy range, with long straight sections in line with the experiment(s). Such a decay ring does not exist at CERN today, nor does a high-intensity proton source for the production of the radioactive ions. Nevertheless, the existing CERN accelerator infrastructure could be used as this would still represent an important saving for a beta-beam facility. This paper outlines the first study, while some of the more speculative ideas will need further investigations.

Future plans at ISOLDE

The CERN ISOLDE facility has operated for over 30 years delivering beams of exotic ions to an ever-growing user community. The facility went through a major up-grade in the early 1990s with the move from the 600 MeV synchrocyclotron to the 1 GeV PS-Booster proton synchrotron. This was followed by a primary proton beam energy up grade to 1.4 GeV in 1999. Lately, an important step forward was taken with the start of the REX-ISOLDE experiment for charge breeding and post-acceleration of exotic ions. CERN has recently decided on a consolidation project for the facility to assure that the required number of shifts can be delivered in the future. An overview will be given of the on-going consolidation and development programme and its implications on the physics programme, in particular the REX-ISOLDE post-accelerator experiment. An important parameter for a better yield of very exotic elements is the primary proton beam intensity, beam energy and time structure. The possible short-term improvements of, in particular, beam intensity will be discussed in some detail. While the main effort at CERN today goes towards the completion of the LHC, some resources have been found for accelerator R&D. A possible project is a new high intensity proton source at CERN, the superconducting proton linac, which could open the door to the construction of a next generation radioactive beam facility. The possible primary beam characteristics and some design considerations and their implications for such a facility will be discussed. Some ideas for the facility itself, such as the use of antiprotons and muons as new probes, production of a neutrino beam from stored radioactive ions and a preliminary design for a low energy storage ring, will be presented.

Basic plasma investigations on the Frankfurt high intensity proton source with an electrostatic 127° cylinder spectrometer

For the International Fusion Materials Irradiation Facility, a new volume source has been developed and tested in 1999. The plasma generation is performed by means of a filament-driven arc discharge. Besides, a solenoid for the plasma confinement, the ion source is equipped with a filter magnet to control the electron energy in the plasma. Using a 127° cylinder spectrometer, the energy distributions of H +, H 2 +, H 3 + and electrons as a function of different discharge parameters were measured. Based on these investigations, fundamental plasma parameters are derived, such as plasma-wall potential, electron and ion temperatures. Furthermore, with the knowledge of the electron-energy distributions, it is possible to verify the mechanism of the proton generation in the hydrogen plasma. This paper summarizes the results of basic plasma investigations. The goal of these investigations was to get a better understanding of the plasma physics within the proton source. In addition, it was an aim to gain insight into the trend of experimental results and to be able to improve the ion source performance.

Improvement of beam emittance of the CEA high intensity proton source SILHI

The emittance of the intense proton beam extracted by the source SILHI at Commisariat à l’Energie Atomique (CEA)-Saclay is a key parameter for the design of the IPHI Project RFQ. This parameter has a relevant role even for the design of an intense proton source for the TRASCO project of Istituto Nazionale di Fisica Nucleare (INFN). The tests performed in the framework of CEA-INFN collaboration have been mainly devoted to a 75 mA beam emittance investigation injecting different gases in the beam line. The results show that the rms normalized emittance decreases up to a factor 3 while the beam losses induced by recombination are contained within 5%. Normalized emittance in r-r′ plane of about 0.1 π min mrad have been obtained using Ar and Kr.

High Intensity Proton Source with Low Energy Spread

A high intensity proton source with a low energy spread is described. The source produces beams of about 60% protons with an energy spread of 0.4 eV or less.