GSI, Darmstadt
The FAIR accelerator project at GSI should increase the intensity of primary proton and heavy ion beams by up to two orders of magnitude, relative to the existing GSI facility. In addition to the design of the new synchrotrons and storage rings, the intensity upgrade of the existing UNILAC linac and SIS-18 synchrotron plays a key role for the FAIR project. In order to reach the FAIR design beam parameters several challenges related to operation with high brightness, high current beams in SIS-18 and in the new SIS-100 have to mastered. Important issues are
- the minimization of beam loss caused by space charge induced resonance crossing and the identification of appropriate working points.
- The control of coherent beam instabilities in the presence of space charge, image currents and different ring impedance sources.
- Beam quality conservation during the rf cycle.
- The control of dynamic vacuum pressure during operation with medium charge state heavy ions.
Fermilab, Batavia, Illinois
Cooling of hadron beams is often the only technique by which accelerator facilities around the world achieve the necessary beam brightness necessary for their physics research. In this paper, we will give an overview of the latest developments in hadron beam cooling, for which high energy electron cooling at Fermilab’s Recycler ring and bunched beam stochastic cooling at Brookhaven National Laboratory’s RHIC facility represent two recent major accomplishments. Novel ideas in the field will also be introduced.
BNL, Upton, Long Island, New York
Operational experience on crossing RHIC transition as well as observed beam dynamics effects are described. The techniques to provide the successful transition crossing without beam losses and deterioration of the beam quality in both transverse and longitudinal plane are reviewed. Presently the ion beam intensity is limited by the transverse instability happenning at the transition region. It was observed that the threshold of the instability was significantly affected by the presence of the electron cloud. The results of recent studies of the intensity limiting instability are presented.
BNL, Upton, Long Island, New York
A strong interest in running RHIC at low energies in a range of 2.5-25 GeV/nucleon total energy of a single beam has emerged recently. Providing collisions in this energy range, which in RHIC case is termed “low-energy” operation, will help to answer one of the key questions in the field of QCD about existence and location of critical point on the QCD phase diagram. To evaluate the challenges of RHIC operation at such low energies there have been several short test runs during RHIC operations in 2006, 2007 and 2008. The beam lifetime observed during the test runs was clearly limited by machine nonlinearities. This performance can be improved provided sufficient time is given for machine development at these low energies. After the lifetime caused by nonlinearities is improved the strongest limitation comes from transverse and longitudinal Intra-beam Scattering (IBS), and ultimately by the space-charge limit. A significant luminosity improvement can be provided with electron cooling applied directly in RHIC at low energies. This report summarizes various beam dynamics limiting effects and possible improvement with electron cooling.
BNL, Upton, Long Island, New York
Intra-beam scattering (IBS) is the limiting factor of the luminosity lifetime for RHIC operation with heavy ions. Over the last few years the process of IBS was carefully studied in RHIC with dedicated IBS measurements and their comparison with the theoretical models. Recently, in order to suppress transverse IBS growth, a new lattice was designed and implemented in RHIC, which lowered the average arc dispersion by 30%. This lattice became operational during RHIC Run-8. We review the IBS suppression mechanism, IBS measurements before and after the lattice change, and comparisons with predictions.
LANL, Los Alamos, New Mexico
University of Tennessee, Knoxville, Tennessee
TRIUMF, Vancouver
ORNL, Oak Ridge, Tennessee
KEK, Ibaraki
At the 39th ICFA Advanced Beam Dynamics Workshop HB 2006 we reported on first results of a test of nanocrystalline diamond foils developed at ORNL under operational conditions at the Los Alamos Proton Storage Ring (PSR). We have continued these tests during the 2006 and 2007 run cycles and have been able to compare the diamond foils with the foils that are normally in use in PSR, which were originally developed by Sugai at KEK. We have gathered valuable information regarding foil lifetime, foil related beam loss and electron emission at the foil. Additional insight was gained under unusual beam conditions where the foils are subjected to higher temperatures. In the 2007 run cycle we also tested a Diamond-like-Carbon foil developed at TRIUMF. A Hybrid-Boron-Carbon foil, also developed by Sugai, is presently in use with the PSR production beam. We will summarize our experience with these different foil types and offer an outlook for future foil activities at PSR.
Fermilab, Batavia, Illinois
The Fermilab Project X R&D program is focused on the design of a new proton source utilizing a superconducting linac to accelerate H-minus ions to 8 GeV (K.E) for injection and accumulation into the permanent magnet Recycler ring. The initial linac runs at a 5 Hz rep-rate with a 1 ms pulse length and 9 mA average current which produce a beam power of 360 kW at 8 GeV. This beam power will provide 2.3 MW at 120 GeV from the Main Injector in addition to 200 kW at 8 GeV for an 8 GeV physics program. The challenges faced with the transport and injection of 8 GeV H- will be discussed. The topics will include uncontrolled beam losses and their mitigation in both the transport and injection processes, injection stripping options, and transverse phase space painting options. A review of the issues that have been highlighted and addressed by numerous authors will be presented. The current plans for continued R&D on H- stripping mechanisms and techniques and in collimation and absorber design will be outlined and initial concepts of the design will be discussed. Upgrade plans for Project X call for a 2 MW facility at 8 GeV. The additional challenges faced in the upgrade will be outlined.
KEK, Ibaraki
University of Tennessee, Knoxville, Tennessee
ORNL, Oak Ridge, Tennessee
At the 39th ICFA HB2004 workshop and the EPAC-2006 conference, we reported the lifetime and properties of the HBC (Hybrid type Boron-mixed Carbon) foils, a newly developed material, measured by the use of a 3.2 MeV Ne+ ion beam, which deposits significant energy in the foil due to the heavy ion. The content reported showed superior durability against high temperature damage due to foil deformation, thickness reduction and pinhole production at 1700 ± 100K compared with the cluster foils made by the CADAD method. This time, we measured the lifetime of the HBC-foils and the high quality nanocrystalline diamond foils including commercially available foils at 1800 ± 100K which induces the high temperature damage. The measurements were performed by using the KEK-650 keV high intensity H- and DC beam, which generates the same energy deposition as the RCS of J-PARC. In this workshop, we report the results obtained.
KEK, Ibaraki
The beam commissioning of J-PARC linac has been started since November 2006, and the initial commissioning has been completed in September 2007. Since then, the linac beam has been supplied to the succeeding RCS (Rapid Cycling Synchrotron) for its commissioning. The emphasis of the linac tuning has been shifted to the stabilization of the beam parameters, and better beam availability has gradually been required for the linac operation. On the other hand, the average beam power is rather limited because we are still in the initial commissioning stage for RCS and MR (Main Ring). The hourly average of the beam power from RCS is limited to 4 kW due to the available beam dump capacity. Accordingly, we still have little experience on the machine activation with a high-power and stable beam operation. In this regard, we are in a transitional stage for our linac from commissioning to operation. In this paper, we present the current linac performance and operational experiences obtained so far after briefly reviewing the commissioning history. Particular emphasis is put on the technical challenges we faced up to the present. Future plans to increase the beam power are also discussed.
BNL, Upton, Long Island, New York
MIT, Middleton, Massachusetts
The design status of the high luminosity electron-ion collider, eRHIC, is presented. The goal of eRHIC will be to provide collisions of electrons and possibly positrons) on ions and protons in the center-of-mass energy range from 25 to 140 GeV, at luminosities exceeding 1033 cm-2s-1. A considerable part of the physics program calls for a high polarization level of electrons, protons and He3 ions. The electron beam is accelerated in a recirculating energy recovery linac. Major R&D items for the electron beam include the development of a high intensity polarized source, studies of various aspects of energy recovery technology for high power beams and the development of compact magnets for recirculating passes. In a linac-ring scheme the beam-beam interaction has several very specific features which have to be thoroughly studied. In order to maximize the collider luminosity, several upgrades of the existing RHIC accelerator are required. Those upgrades may include the increase of total beam intensity as well as transverse and longitudinal cooling of ions and protons.
Jefferson Lab, Newport News, Virginia
TRIUMF, Vancouver
A conceptual design of a ring-ring electron-ion collider based on CEBAF with a center-of-mass energy up to 90 GeV at luminosity up to 1035 cm-2s-1 has been proposed at JLab to fulfil science requirements. Four interaction points on two crossing straight sections of Figure-8 shape rings are planed for collisions of both highly polarized electron and light ion beams. The Green field design of the ion complex including electron cooling and new way of organizing interacting regions are directly aimed at full exploitation of science program. Here, we summarize design progress including collider ring and interaction region optics with chromatic aberration compensation. Stacking of ion beams in an accumulator-cooler ring, beam-beam simulations and a faster kicker for the circulator electron cooler ring are also discussed.
GSI, Darmstadt
The double synchrotron complex SIS100 and SIS300 is the central part of the FAIR project. SIS100 is a fast ramped superconducting synchrotron optimized for high intensity, low-charge state heavy ion operation. However, similar to the existing heavy ion synchrotron SIS18, SIS100 will also be used to accelerate all other ion species down to protons, In order to enable such a flexible operation and to avoid transition energy crossing, a triplet structure with three independent power circuits has been chosen. For the low charge state operation, a new lattice design concept has been applied which provides an optimized separation of ionized beam particles. Low charge state operation is enabled by means of the cryopumping of the actively cooled, thin wall vacuum chambers. The stability of the residual gas pressure is an essential precondition for this operation. The project status and the status of the major device developments will be presented.
RIKEN/RARF/CC, Saitama
RIKEN Nishina Center, Wako, Saitama
ANL, Argonne, Illinois
The accelerator complex for RIBF factory in RIKEN consists of the four ring cyclotrons with an injector linac. It can boost the energy of output beams from the linac up to 440 MeV/nucleon for light ions and 350 MeV/nucleon for very heavy ions. The first beam from the accelerator complex was successfully extracted at the end of 2006. An 28GHz SC-ECR ion source will be installed at the front end of the injector linac on a 100kV HV platform to increase the beam intensity of very heavy ions such as uranium. Beam dynamics from the ion source to the exit of the injector were simulated using TRACK. How much space charge forces affect on beam qualities in the successive ring cyclotrons will be discussed.
Soreq NRC, Yavne
ACCEL, Bergisch Gladbach
The Soreq Applied Research Accelerator Facility (SARAF) is built to be used for basic research, medical research, neutron based non-destructive testing and radio-pharmaceuticals development and production. The accelerator, designed and constructed by Accel Instruments GmbH, starts with a 5 mA, 20 keV/u ECR ion source. A LEBT transports the beam and matches it to a normal-conducting 4-rod RFQ. The RFQ bunches the beam at a frequency of 176 MHz 4 mA ions and accelerate the ions to 1.5 MeV/u. A 0.65 m long MEBT transports and matches the beam into the superconducting linac. The 20 m long linac is composed of six cryostats that contain a total of 44 half-wave resonators optimized for β0=0.09 and 0.15, which are kept at a temperature of 4.5 K by liquid helium. In order to achieve the dose rate criterion for hands-on maintenance, beam loss is limited to 1 nA/m. Extensive beam dynamics simulations, including error analysis with high statistics, indicate that beam loss will indeed be below the above mentioned criterion. Currently, Phase I of the SARAF linac, including the ion source, LEBT, RFQ, MEBT and the first SC cryostat, is installed on site and is undergoing commissioning.
ORNL RAD, Oak Ridge, Tennessee
ORNL, Oak Ridge, Tennessee
Space charge effect has an impact on emittance measurement of low energy H- ion beam injected into the SNS RFQ. This paper presents numerical investigations of space charge effect of the beam on transverse emittance measurement using an Allison style scanner attached to the front-end test stand at SNS. The investigations are based on mathematical modelling the emittance measurement by the scanner taking into account space charge of the beam. We present a method of emittance data analysis that includes the modelling and allows more accurate measurements of the emittance. We also give an example of the emittance measurement with the scanner applying the developed method.
STFC/RAL, Chilton, Didcot, Oxon
STFC/RAL/ISIS, Chilton, Didcot, Oxon
STFC/RAL/ASTeC, Chilton, Didcot, Oxon
Imperial College of Science and Technology, Department of Physics, London
In order to contribute to the development of high power proton accelerators in the MW range a front end test stand (FETS) is being constructed at the Rutherford Appleton Laboratory (RAL) in the UK. The aim of the FETS is to demonstrate the production of a 60 mA, 2 ms, 50 pps chopped beam at 3 MeV with sufficient beam quality. Therefore a comprehensive set of diagnostic tools have been developed or are in the design and construction phase. To improve the beam quality delivered by the Penning H- ion source using a slit extraction, a pepper pot emittance measurement device and a 2D-transversal profile scanner has been built and used on the ion source development rig and results of the beam measurements will be presented. As destructive diagnostic devices suffer from the high beam power deposited on the device surfaces, two new diagnostic devices based on the photo detachment principle are under construction: A laser wire scanner allowing the reconstruction of the full 2D-transversal density distribution using tomographic techniques and an emittance scanner device. The design and status of construction of both devices will be presented and new ideas for the data analyses discussed.
J-PARC, KEK&JAEA, Ibaraki-ken
KEK, Ibaraki
JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken
J-PARC, KEK & JAEA, Ibaraki-ken
The beam commissioning of the J-PARC Main Ring synchrotron (MR) has been started from May of this year. A single bunch beam from 3 GeV Rapid Cycling Synchrotron (RCS) was injected to the ring through 3-50 beam transporting (3-50BT) and then was extracted to the beam dump after 1000 turns (typically) without acceleration. The beam intensity was 4·1011 ppb that is 2 orders of magnitude smaller than that of the design intensity. The beam diagnostic system was used to establish the beam operational parameters. The system includes the instrumentations as follows; 3 types of Current Transformers (CTs), DCCT, fast CT (FCT), and Wall Current Monitor (WCM); Beam Position Monitors (BPMs); proportional counter type Beam Loss Monitors (BLMs) at each quadropole magnet; horizontal and vertical tune monitors with exciter systems; and 3 types of beam profile monitors, Multi Wire Profile Monitors (MWPMs) at 3-50BT and downstream of injection septa, a horizontal Flying Wire Profile Monitor (FWPM) and a vertical residual gas Ionization Profile Monitor (IPM) in the ring. At the workshop, the present status of the system will be presented.
ANL, Argonne, Illinois
CERN, Geneva
The International Program Committee of the Workshop and its Chairman have charged us with the following three questions:
- Recent trends in high-intensity proton/ion beam facilities?
- Critical challenges and key research areas for substantial beam power increases?
- Necessary improvements in theory and simulation tools?