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| MO1002 | Commissioning and Initial Operating Experience with the SNS 1-GeV Linac | linac, SNS, emittance, beam-transport | 1 | ||
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The Spallation Neutron Source accelerator complex consists of a 2.5 MeV H- front-end injector system, a 186 MeV normal-conducting linear accelerator, a 1 GeV superconducting linear accelerator, an accumulator ring and associated beam transport lines. The SNS linac was commissioned in five discrete runs, starting in 2002 and completed in 2005. The remainder of the accelerator complex was commissioned in early 2006. With the completed commissioning of the SNS accelerator, the linac has begun initial low-power operations. In the course of beam commissioning, most beam performance parameters and beam intensity goals were achieved at low duty factor. A number of beam dynamics measurements have been performed, including emittance evolution and sensitivity to mismatch of the input beam. The beam commissioning results, achieved beam performance and initial operating experience of the SNS linac will be presented.
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| MOP003 | A Shared Superconducting Linac for Protons and Muons | linac, proton, factory, collider | 34 | ||
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A future Fermilab proton driver* based on TESLA superconducting linac modules can provide protons to produce the muons and also accelerate the muons to be used for a neutrino factory or muon collider. Recent advances in muon cooling** imply muon emittances that are compatible with the 1300 MHz accelerating structures that are the basis for the ILC design. In the example discussed here, H- ions are accelerated to 8 GeV in the superconducting linac, then stripped, stored and bunched in a ring while the linac cavities are rephased for muon acceleration. Then the protons are extracted from the ring to produce pions and muons which are cooled in about six hundred meters, accelerated to a few GeV and injected into the linac at the point for acceleration to add 7 GeV. By recirculating the muons in the constant frequency section of such a proton driver linac, even higher energies can be achieved quickly so that losses from muon decay are minimized. By adding additional refrigeration and RF power, the repetition rate of the linac can be increased to make large increases in the average flux of a neutrino factory and the average luminosity of a muon collider.
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*G. W. Foster and J. A. MacLachlan, Proceedings of LINAC 2002, Gyeongju, Korea |
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| MOP021 | Recent Operation of the ORELA Electron LINAC at ORNL for Neutron Cross-Section Research | gun, electron, klystron, vacuum | 79 | ||
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The ORNL electron LINAC, ORELA, began operation in 1969 and has been instrumental in providing improved neutron cross section data for many isotopes over the 0.002-60 MeV energy range. The ORELA utilizes a 4-30 ns <1000 Hz pulsed gridded electron gun, a 4 section RF Linac, and a water-cooled and moderated tantalum target to generate short neutron pulses. The short pulse lengths and long flight path provide high neutron energy resolution. Beam energy can range up to 180 MeV and a neutron production rate of up to 1014 n/sec can be generated with 50 kW of beam power. Recent operation is a 8 ns, 525 Hz pulse and a target power of 5-10 kW. RF power for the accelerator sections are provided by four 24 MW 1300 MHz klystrons. Recent activities have included improvements to the accelerator vacuum, klystrons, interlocks and other upgrades. The current ORELA program is focused on cross-section measurements for the Nuclear Criticality Safety Program and for nuclear astrophysics. Detection and data analysis capabilities have been developed for making highly accurate measurements of neutron capture, neutron total, (n,alpha), and (n,fission) cross sections simultaneously on different beam lines.
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| MOP028 | Creation of Peaks in the Energy Spectrum of Laser-Produced Ions by Phase Rotation | laser, proton, ion, acceleration | 97 | ||
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Efficient acceleration of ions with use of very high electromagnetic field created by a high power laser has been paid attention because of its attainable very high acceleration gradient. Its intensity, however, has exponentially decreases according to the increase of its energy, which causes essential difficulty for its real application. For the quality improvement of laser-produced ions in their energy spreads, a scheme to apply an additional RF electric field synchronous to the pulse laser, called “Phase Rotation”,* has been applied to the ions produced from the thin foil target 3 and 5 mm, in thickness by irradiation of focused Ti:Sapphire laser with the wave length of 800 nm after optimization of the ion production process with use of real time observation of ion energy by TOF measurement.** Energy peaks with the spread of 7 % have been created in the energy spectrum at the positions depending on the relative phase between the pulse laser and the RF electric field. Possible application of “Phase Rotated” laser-produced ion beam is also to be discussed.
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* A. Noda et al., Laser Physics, Vol. 16, No.4, pp.647-653(2006). |
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| MOP031 | Beam Distribution System for the MSU-RIA Driver Linac | kicker, emittance, linac, simulation | 106 | ||
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The proposed Rare Isotope Accelerator (RIA) facility will deliver up to 400 kW of any stable isotope to multi-target areas to create radioactive ion beams using either Isotope Separation On Line or Particle Fragmentation methods. Operational and programmatic efficiency will be best served by a system that can simultaneously distribute the beam current over a large dynamic range to several targets. The proposed RIA beam switchyard uses an rf kicker-magnetic septum system to distribute the beam to multi-target areas on a micro-bunch by micro-bunch basis. The micro-bunches can be differentially loaded in the RIA driver linac front end utilizing a scheme similar to that successfully used at Mainz and JLAB CEBAF facility. In these cases, consecutive electron micro-bunches are deflected by an rf kicker and their intensity separately adjusted through variable apertures with an identical second rf kicker returning the micro-bunches on-axis. The feasibility of using a similar system in RIA driver linac front end was explored. The overall concept of the RIA beam distribution system including the differential bunch loading system and the results of the beam dynamics studies will be presented.
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| MOP033 | The Operation Concept of SARAF | controls, cryogenics, instrumentation, radiation | 109 | ||
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The Soreq Applied Research Accelerator Facility (SARAF) is a 5 - 40 MeV, 0.04 -2 mA proton/deuteron RF superconducting linear accelerator, which is under construction at Soreq NRC and is planned to start generating a beam by the end of 2010. SARAF will be a multi-user facility, whose main activities will be neutron physics and applications, radio-pharmaceuticals development and production, and basic nuclear physics research. The operational concept of SARAF will be ‘one target at a time’ and during irradiation, appropriate shielding will enable preparation and maintenance at other stations. This paper presents the planned facility operation program, the planned operations group, the location and layout of the main control room and the architecture of the main control system, including its interfaces with safety and applications. Emphasis is given to the design considerations for each of the discussed subjects.
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| MOP039 | The SPL (II) at CERN, a Superconducting 3.5-GeV H- Linac | linac, proton, injection, simulation | 127 | ||
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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 4 - 5 MW beam power, the SPL can be the proton driver for a next generation ISOL-type radio-active beam facility ("EURISOL") and/or supply protons to a neutrino facility (conventional superbeam + beta-beam or neutrino factory). Furthermore the SPL can replace Linac2 and the PS booster, 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 (3.5 GeV instead of 2.2 GeV) while the length is reduced by 40%. At a repetition rate of 50 Hz, the linac re-uses decommissioned 352.2 MHz RF equipment from LEP in the low-energy part. Beyond 90 MeV the RF frequency is doubled, and from 180 MeV onwards high-gradient SC bulk-niobium cavities accelerate the beam to its final energy of 3.5 GeV. This paper presents the overall design approach, together with the technical progress since the first conceptual design in 2000.
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| MOP050 | Construction Plans for the LENS Proton Linac | proton, rfq, klystron, linac | 156 | ||
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The Low Energy Neutron Source (LENS) at Indiana University will provide moderated neutrons in the meV energy range for materials and neutron physics research as well as MeV energy range neutrons for creating a high flux neutron test environment. Neutrons will be generated by colliding 13 MeV or 21 MeV protons with a Be target. Since December 2004, we have used an existing RFQ and DTL, we have been able to deliver a 0.5% duty factor a 10 mA, 7 MeV beam to a Be target mounted next to a frozen methane moderator*. By early 2007, an additional 7 MeV to 13 MeV DTL section will be added and klystrons will be used to power the RFQ and DTL sections. This will improve the output to 3% duty factor with 20 mA at 13 MeV. A new 75 keV, 150 mA proton injector and 100 mA, high duty factor RFQ is being constructed to replace the original 3 MeV RFQ at a later date. The peak beam current available from the new injector and RFQ will increase to 50 mA with a duty factor of at least 5% or up to 100 mA with lower duty factor. In addition, a 13 MeV to 22 MeV DTL is planned to boost the maximum instantaneous flux available from the neutron source up to about 1012 n/s/cm2.
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V. P. Derenchuk, et al., "The LENS 7 MeV, 10 mA Proton Linac," PAC05, p. 3200. |
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| MOP055 | Transport of LANSCE-Linac Beam to Proposed Materials Test Station | quadrupole, diagnostics, emittance, dipole | 171 | ||
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Refurbishment of Experimental Area A and installation of a Materials Test Station is planned at the Los Alamos Neutron Science Center (LANSCE). This paper describes the beamline to transport 800-MeV protons from the accelerator to Area A. The beamline has the minimum number of quadrupoles necessary to achieve the desired instantaneous beam parameters at the target, the appropriate beam-centroid excursions at the split target for painting the two target halves, and a beam-centroid crossover upstream of the target to facilitate shielding of upstream components from backstreaming neutrons. Options in the composition of the raster-magnet section represent trade-offs between the number of magnets and the severity of the effects of magnet failures. Beam diagnostics are an integral part of the beamline design. Instantaneous and painted beam sizes at the target can be inferred by observing the beam at properly chosen upstream locations. A beamline spur to a tune-up beam dump is planned.
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| TU1003 | Modern Electron Induction Linacs | electron, induction, cathode, linac | 208 | ||
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Several high power induction linacs are in existence and a couple are being built around the world. Typically, they are capable of delivering about 100 micro-coulombs of e-beam to the target in a single burst and are built for radiographic application. DARHT 2nd Axis induction linac under construction at Los Alamos National Laboratory is the first of its kind, designed to deliver multiple e-beam pulses to the target. This incorporates the latest advances in the induction linac technology. An overview of the existing as well as the DARHT induction linac will be presented in this paper.
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| TU2002 | Laser-Based Heavy Ion Production | ion, laser, plasma, rfq | 219 | ||
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We have focused on high brightness of induced plasma in Laser Ion Source (LIS) to provide intense highly charged ions efficiently. To take the advantage of the intrinsic density of the laser plasma, Direct Plasma Injection Scheme (DPIS) has been developed. The induced laser plasma has initial expanding velocity and can be delivered directly to the RFQ. Extraction electrodes and focusing devices in LEBT are not needed. Since 2004, a newly designed RFQ has been used to verify the capability of the new ion production scheme. We succeeded to accelerate 60 m A of Carbon beam and 60 mA of Aluminium beam. We have also tried to understand plasma properties of various species by measuring charge states distributions and time structures, and are now ready to accelerate heavier species. Currently Silver 15+ beam is planned to be accelerated. In the conference, design strategies and detailed techniques for the DPIS will be described based on the measured plasma properties of various elements and new findings obtained from recent acceleration experiments. The durability and the reproducibility will be also explained.
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| TUP005 | Design of an RFQ-Based Neutron Source for Cargo Container Interrogation | rfq, ion-source, ion, quadrupole | 253 | ||
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An RFQ-based neutron generator system is described that generates pulsed neutrons for the active screening of sea-land cargo containers for the detection of shielded special nuclear materials (SNM). A microwave-driven deuteron source is coupled to an electrostatic LEBT that injects a 40 mA D+-beam into a 6 MeV, 5.1 meter-long 200 MHz RFQ. The RFQ has a unique beam dynamics design and is capable of operating at duty factors of 5 to10% accelerating a D+ time-averaged current of up to 1.5 mA at 5% duty factor, including species and transmission loss. The beam is transported through a specially-designed thin-window into a 2-atmosphere deuterium gas target. A high-frequency dipole magnet is used to scan the beam over the long dimension of the 5 by 40 cm target window. The source will be capable of delivering a neutron flux of 2·107 n/(cm2·s) to the center of a cargo container. Details of the ion source, LEBT, RFQ beam dynamics and gas target design are presented.
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| TUP010 | The Beam Halo Monitor of SARAF | proton, background, vacuum, scattering | 265 | ||
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A main requirement for the SARAF accelerator is ‘hands-on’ maintenance, which implies a maximum beam loss of 1 nA per meter. In Phase I of SARAF (4-5 MeV ions at full current), we need to map the beam halo (BH) down to below 1 nA in order to predict, using beam dynamics calculations, the beam loss in the full accelerator. Mapping the halo of a 4 MeV, 2 mA ion beam down to below 1 nA is unprecedented, so we developed a BH monitor, which incorporates a direct charge measurement and several nuclear techniques, including Rutherford scattering 197Au(p,p)197Au, 7Li(p,n)7Be leading to both neutrons and the radio-isotope 7Be (measured offline post irradiation) and 19F(p,alpha)16O leading to high energy gamma rays. The current is derived using published cross sections. In this paper, we present the SARAF Phase I BH monitor and describe the various measurement techniques. In addition, results of feasibility studies at the Pelletron accelerator of the Weizmann Institute are given. The results of the various current measurement techniques are consistent with the standard Pelletron Faraday Cup to better than 20%. This is sufficient for mapping the SARAF beam halo to the desired accuracy.
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| TUP037 | Possible Upgrade Paths for the LANSCE H- Injector | rfq, ion, ion-source, linac | 330 | ||
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The LANSCE linac presently provides both H- and H+ beams to several user facilities. The H- injector uses a cesiated, multi-cusp field, surface converter source operating at duty factors between 10 and 12%, coupled to a Cockcroft-Walton (CW) accelerator to provide peak beam currents of ~15 mA for the LANSCE linac. In an effort to raise the peak beam current available to the majority of the H- users, we are pursuing two options. The first is a low duty factor H- ion source and a 750 keV RFQ that would provide ~25 mA of peak current for use by the Lujan and pRad programs. The second is a low frequency buncher for the existing 80 keV beam transport located inside the CW dome that could provide about a factor of two increase in the peak beam current for the WNR program. This paper will present these two options.
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| TUP049 | Metal-Based Photocathodes For High-Brightness RF Photoinjectors | laser, cathode, gun, vacuum | 358 | ||
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Advanced high brightness RF gun injectors require photocathodes with fast response, high quantum efficiency and good surface uniformity. Metal films deposited by various techniques on the gun back wall could satisfy these requirements. Two new deposition techniques have been recently proposed, i.e. pulsed laser ablation and vacuum arc. Several samples of various materials have been deposited by the two techniques: The emission performance and morphological changes induced on the cathode surface by laser beam are compared and discussed.
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| TUP067 | Tune-up Scenario for Debuncher System in J-PARC L3BT | injection, simulation, monitoring, linac | 406 | ||
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We plan to start beam commissioning of J-PARC linac and the succeeding beam transport line in December 2006. The beam transport line, to which we refer as L3BT, has two key functionalities to satisfy the requirements for the succeeding ring injection. One is to reduce the momentum jitter and momentum spread, and the other is to scrape off the transverse tail. To realize the former functionality, a debuncher system is installed in L3BT which enables longitudinal gymnastics of the beam to reduce the momentum spread at the ring injection. In this presentation, the tune-up scenario for the debuncher system is presented together with simulation results on the effects of debuncher system.
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| TUP070 | Comparison of Phase Scan vs Acceptance Scan for the SNS DTL | linac, simulation, SNS, Spallation-Neutron-Source | 415 | ||
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There are two widely used techniques for setting the rf set-point of the Drift Tube Linac (DTL). The Phase Scan and the Acceptance Scan techniques were applied to the SNS DTL and were benchmarked against each other. Commissioning data indicate that both techniques produce quite consistent results and the model used is quite accurate. Both of the models are based on multiparticle tracking with space charge effects.
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| TUP091 | Choice of Ion Linac as Neutron Generator for Contraband-Detection System | proton, linac, rfq, background | 475 | ||
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8 Mev proton linac and 4 Mev deuteron linac with working frequency 433 MHz are considered as neutron generator for detection system of explosive and fission. Required beam parameters, target materials, pulsed modulation and detection methods are discussed. Possible schemes of accelerating system of contraband detection complex are proposed. One supposes using of RFQ for deuteron linac and RFQ with IH cavity as proton one. Choice is determined by some few criterions: cost, sizes, safety, hardness of manufacturing and tuning.
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| THP056 | Design of 325-MHz Single and Triple Spoke Resonators at FNAL | linac, proton, vacuum, pulsed-power | 707 | ||
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We present the design of two 325 MHz superconducting single spoke resonators at β=0.22 and β=0.4 and a 325 MHz superconducting triple spoke resonator at β=0.62 for the front end of a 2 MW proton linac. We describe the optimization of the spoke resonator electromagnetic performance and how the resonator structural integrity and shape is ensured. We describe the mechanical design of the slow tuner mechanism and, via a coupled ANSYS-MWS analysis, how the mechanism adjusts the resonator operating frequency. The RF design of the power coupler is also presented
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| THP068 | RF Characteristics of the SDTL for the J-PARC | linac, insertion, proton, synchrotron | 740 | ||
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For the J-PARC linac, a Separated type DTL (SDTL) is used to accelerate an H- ion beam from 50MeV to 191MeV. The SDTL consists of 32 tanks and the operating frequency is 324MHz. It has 4 drift tubes and 2 half tubes (5cells), 2 fix tuners, 1 movable tuner and 1 RF input coupler. The inner diameter is 520mm and the length is approximately from 1.5m (SDTL1) to 2.5m (SDTL32). The focusing magnets are set between the tanks. We have measured the RF characteristics of the SDTL tanks and adjusted the field distribution since last summer. The measured Q value was above 90% of ideal SUPERFIS value, the field distribution was adjusted within ±1% for all the tanks. In this paper, the results of RF measurements of the SDTL tanks are described.
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| THP085 | Transportation of the DTL/SDTL for the J-PARC | acceleration, alignment, linac, focusing | 782 | ||
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Three DTL tanks and 32 SDTL tanks for the Japan Proton Accelerator Research Complex (J-PARC) were assembled at KEK site. After the assembling, the aging of the DTL1 and 12 SDTL tanks and the beam acceleration test for the DTL1 was done. And then all the DTL and SDTL tanks have to be transported form KEK to JAEA. The distance is about 95km and special air suspension trailer is used. To confirm the effect to the accuracy of the drift tube alignment, we measured the displacement of the drift tube positions before and after the transportation by using a hot model tank. As a result of the test, the displacement of the drift tubes by the transportation was less than 0.02mm which meets our requirements. Based on this result, all the DTL and SDTL tanks were transported form KEK to JAEA. In this paper, the transportation results of the hot model tank and the DTL/SDTL tanks are described.
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| THP091 | Experimental Study of Positron Production from Monocrystalline Targets at the KEKB Injector Linac | positron, electron, radiation, linac | 797 | ||
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Intense positron sources are widely investigated for the next-generation of linear colliders and B-factories. A new method utilizing an axially-oriented crystal as a positron-production target is one of the bright schemes since it provides a powerful photon source through channeling and coherent bremsstrahlung processes when high-energy electrons penetrate the target. A series of positron-production experiments with tungsten crystal alone and diamond target combined with an amorphous tungsten plate have been carried out at the KEKB injector linac. The tungsten crystals with different thicknesses (2.2, 5.3, 8.9, 12.0 and 14.2 mm) and the diamonds with different thicknesses (4.57 and 7.25 mm) were tested on a goniometer by using 4 and 8-GeV electron beams, respectively. The positron-production yields were measured with a magnetic spectrometer at the positron momentum of 10 and 20 MeV/c. In this report the experimental results are summarized on the enhancements of the positron yield from these crystal targets compared to amorphous targets of the same thickness.
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*Email address: tsuyoshi.suwada@kek.jp |
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| FR2001 | Targets and Ion Sources Development at ISAC-TRIUMF | ion, ion-source, laser, proton | 823 | ||
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The ISAC facility is operational since 1998, we utilize the proton beam from the TRIUMF H- cyclotron to produce the radioactive ion beams (RIB) via the isotopic separation on line (ISOL) method. The ISAC facility is designed to accommodate 100 μA proton beam at 500 MeV. Since beginning operation irradiation currents have progressively increased from initial values of ~ 1 μA to present levels of up to 75 μA on refractory metal foil targets and recently equally on composite carbide targets. Beyond the 50 μA limit the target has to be cooled. A new target equipped with fins has been developed that can sustain proton beam up to 100 μA. The RIB intensities depend not only on the target but also on the ability to produce ion beam. The ion sources design for on-line applications are extremely important because of the close contact with the target. They must sustain high radiation field and operate in a large gas pressure range. In order to produce a larger range of beam we are looking at other types, ECR, FEBIAD, negative and the laser ion sources. Report on the recent progress accomplished during the past years will be made.
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