| Paper | Title | Page |
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| THPC049 | Progress in the Beam Preparation for the Multi-turn Extraction at the CERN Proton Synchrotron | 3089 |
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| A new type of extraction based on beam trapping inside stable islands in the horizontal phase space will become operational during 2008 at the CERN Proton Synchrotron. A series of beam experiments was carried out to prove loss-less capture with high intensity and multi-bunched beams, up to 1500·1010 protons per pulse, in preparation of the extraction commissioning. These fundamental steps for the new Multi-turn Extraction are presented and discussed in details. | ||
| THPP086 | Diamond Stripper Foil Experience at SNS and PSR | 3563 |
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| The SNS is currently operating at about 15% of the 1.4 MW design power, and the diamond stripper foils developed at ORNL continue to perform well. Several corrugated, nanocrystalline diamond stripping foils have been tested at SNS. Beyond about 300 C of injected charge, significant distortion and darkening of the foils is observed. These foils are currently limited in freestanding area to about 17x25 mm due to stress-induced tears in larger foils; this limit positions the residual silicon wafer mounting handle close enough to the circulating beam that additional losses have been observed. The PSR experience with these diamond foils has been promising, with the interesting observation that both the foil current due to secondary emission of electrons and the thermionic foil current are reduced for diamond foils relative to LANL/KEK foils. For comparable thickness foils, losses due to the Ho yield also appear to be higher for diamond. A recent development in our foil preparation has been a change to nano-seeded nucleation from the earlier microcrystal slurry ultrasonic abrasion technique. This has led to a more reproducible and uniform foil morphology with smaller crystallites. | ||
| THPP087 | 4 GeV H- Charge Exchange Injection into the PS2 | 3566 |
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| The proposed PS2 will accelerate protons from 4 to 50 GeV. The required beam intensity and brightness can only be achieved with a multi-turn H- charge exchange injection system, where the small emittance injected beam is used to paint the transverse phase space of the PS2 machine. This paper describes the constraints and conceptual design of the H- injection system and its incorporation into the present PS2 lattice. The requirements for the special injection system elements are described, in particular the injection chicane and painting magnet systems and the charge exchange foil. Some key performance aspects are investigated, including the stripping efficiency, expected emittance growth and beam loss arising from the simulated number of multiple foil traversals, together with estimates of foil heating. | ||
| THPP088 | Design Considerations for the PS2 Beam Dumps | 3569 |
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| Studies have been made to evaluate and differentiate necessary beam disposal functions for the proposed PS2 accelerator. The paper describes briefly the different beam dump functionalities required for the PS2 machine and its transfer lines, and makes some first estimates about the expected beam loads. This data has been taken as input for comparing the different technical options for the dump systems, in particular to simulate the radiological impact of different internal or external beam dump concepts. The numbers derived have been used to help in evaluating the feasibility of the technical alternatives. | ||
| THPP090 | Beam Injection and Extraction of SCENT300, A Superconducting Cyclotron for Hadrontherapy | 3575 |
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| SCENT300 is a superconducting cyclotron able to deliver proton and carbon beam at 260 and 300 AMeV respectively. The simulations of the beam injection through the central region, the beam extraction through the electrostatic deflector for Carbon beam and by stripper foil for the proton beam are here presented. | ||
| THPP091 | One Nano-second Bunch Compressor for High Intense Proton Beam | 3578 |
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About ten bunches of 2MeV proton rf-linac with an average current of 150mA at 175 MHz will be deflected by kicker on different paths into a magnetic bending system. Passing this optimized geometry they approach each other longitudinaly (βλ = 0.114m) and arrive at the same time at the focus of the dipole system. For longitudinal focussing of the merged bunches a rebuncher cavity is included in the bending system. The motivation and the layout of the whole project, "Frankfurter Neutronen Quelle am Stern-Gerlach Zentrum" (FRANZ), were presented in details in previous conferences*,**. More accurate investigation results in a revision of the preliminary concept. For a theoretical proof of principle one trajectory with the biggest path length of a new geometry is calculated by a multi particle beam dynamics program (LORASR). Preliminary investigations showed, that magnetic fringing fields and bunch-bunch interactions have to be included as detailed as posible in the beam simulations. In this paper the beam dynamics results from LORASR-simulations, the new geometry and the code development for the bunch compressor are discussed in details.
*L. P. Chau et al. Proc. of the Eur. Part. Acc. Conf., Edinburgh (2006), 1690-1692. |
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| THPP093 | Conceptual Design of the PEFP Beam Line | 3581 |
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| In the Proton Engineering Frontier Project (PEFP), 20MeV and 100MeV proton beams from a 100MeV proton liner accelerator will be supplied to users for proton beam applications. Switch magnets will share the beam to three directions, two fixed beam lines and one AC magnet. The two fixed beam lines will be used for isotope production and power semiconductor production. An AC magnet will distribute the beams to three targets simultaneously. To provide flexibilities of irradiation conditions for users from many application fields, we designed beam lines to the targets with wide or focused, external or in-vacuum, and horizontal or vertical beams. As far as possible we designed the simple beam lines to reduce the construction cost. The details of the beam line conceptual design will be reported. | ||
| THPP094 | The Development of a Fast Beam Chopper for Next Generation High Power Proton Drivers | 3584 |
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The Front End Test Stand (FETS) project at RAL will test a fast beam chopper, designed to address the requirements of high-power proton drivers for next generation pulsed spallation sources and neutrino factories. The RAL ‘Fast-Slow’ chopping scheme for the 2.5 MeV, 280 MHz, ESS Medium Energy Drift Space (MEBT)* is evolving to address the requirements of the 3.0 MeV, 324 MHz, FETS project. The recent adoption of a more efficient optical design for the FETS MEBT** will result in a useful increase in beam aperture and permit an important reduction in the amplitude of the chopper E-fields. A description is given of a 'state of the art' high voltage pulse generator designed to address the FETS 'Slow' chopper requirement. Measurements of output waveform and timing stability are presented.
*M. Clarke-Gayther, "A Fast Beam Chopper for Next Generation High Power Proton Drivers," EPAC04. |
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| THPP096 | Injection Optimisation on the ISIS Synchrotron | 3587 |
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| The ISIS Facility at the Rutherford Appleton Laboratory in the UK produces intense neutron and muon beams for condensed matter research. At its core is a 50 Hz proton synchrotron which, as the commissioning of a new dual harmonic RF system concludes, can accelerate 3.75·1013 protons per pulse from 70 to 800 MeV, delivering a mean beam power of 0.24 MW. The multi-turn charge-exchange injection process strongly affects transverse beam distributions, space charge forces and beam loss, which ultimately limits operational intensity. The evolution of longitudinal distributions and subsequent trapping efficiency is also intimately linked with injection. Optimising injection is therefore a key consideration for present and future upgrades. This paper summarises injection studies including 2D space-charge simulations of the ISIS injection process using the ORBIT code. Comparisons of simulation results with measurements for a range of beam intensities are presented and an assessment is made of a correlated painting scheme in contrast to the usual anti-correlated configuration. | ||
| THPP097 | Commissioning Results of the Kicker Magnet in J-PARC RCS | 3590 |
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| Installation of the kickers in the extraction section of the RCS in J-PARC facility was completed. And they succeeded to extract the 3GeV proton beams in the first beam test. The operation parameters of the kickers agreed well with the parameters which were estimated from the magnetic field measurement and the current test of the power supplys. In this report, we summarized the results of the excitation test and the commissioning of the kicker magnet. The results of the magnetic field measurement showed the good uniformity in the wide range of the aperture. The characteristic feature of each kicker power supply was also measured precisely. Although the rise time and jitter of the output pulse have some minor variation due to the different characteristics of the thyratrons, the degree of variation was acceptably small. Combining the results of the magnetic field measurements, the relation between the charging voltage and the magnetic field was obtained for each kicker. The accelerated beam was successfully extracted at the operation parameters which were obtained from the relationship. The measurements result which was obtained by using the beam is also reported. | ||
| THPP098 | Simulations on a Beam Transport System for the Frankfurt Funneling Experiment | 3593 |
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| The goal of the Frankfurt Funneling Experiment is to multiply beam currents by mergeing two low energy ion beams. Our setup consists of two ion sources, a two beam RFQ accelerator, a multigap deflector and a beam diagnostics. Current work is the design of a new beam transport between RFQ accelerator and deflector and first simulations will be presented. | ||
| THPP100 | Development of New Ion Sources for the Frankfurt Funneling Experiment | 3596 |
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| Funneling is a method to increase beam currents in several stages. The Frankfurt Funneling Experiment is a prototype of such a stage. The experimental setup consists of two ion sources with electrostatic lens systems, a Two-Beam RFQ accelerator, a funneling deflector and a beam diagnostic system. The two beams are bunched and accelerated in a Two-Beam RFQ and the last parts of the RFQ electrodes achieve a 3d focus at the crossing point of the two beam axis. A funneling deflector combines the bunches to a common beam axis. The newly optimized ion sources are adapted to the front end bunching section. First results and measurements will be presented. | ||
| THPP101 | Investigation of Lifetime of the Electronics and the Fiber Optics inside the Niche and the Tunnel in the Slow Extraction Area of SIS100 | 3599 |
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| The loss of ions in the slow extraction area of the SIS100 accelerator project at FAIR can be dangerous for the electronic equipment and fiber optics situated inside the tunnel and niches around. During the slow extraction lost ions irradiate the yoke of the quadrupole magnets and collimator and produce a neutrons flux, which can damage or make single event upset at the electronic devices. Also fiber optic cores fade under the action of irradiation. In the current work the investigation of the dose distribution and neutron fluxes, as well as the calculation of the lifetime of the electronics and fiber optics in different places of the tunnel have been done. By using these results the design of the niches and shielding is planned. | ||
| THPP102 | Radiation Damage Studies for the Slow Extraction from SIS100 | 3602 |
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| During the slow extraction from SIS100 synchrotron 5% of the beam will hit the wires of the electrostatic septum and will be lost. These losses produce very high radiation damage to the superconducting quadrupole doublet situated downstream of the extraction point. These beam losses were simulated with the help of Fluka code for U28+ and Ne5+ beams. Non-zero cross-section and non-zero angular divergence were assumed for the lost beam, allowing distributed modeling of the slow extraction losses. The radiation damage to different layers of the superconducting quadrupole cables was calculated. The lifetime of the s.c. cables of the quadrupoles was found to be too short. Thus, alternative quadrupole designs with higher radiation tolerances were investigated: with stainless steel shielding of the s.c. cables and with a gap in the mid-plane between the s.c. cables. | ||
| THPP103 | Design of the Beam Extraction System of the New Heavy Ion Synchrotrons SIS100 and SIS300 at FAIR | 3605 |
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| The proton and heavy ion synchrotrons SIS100 and SIS300 are the heart of the new FAIR facility which is under construction on the site of the present GSI. All ions from protons to uranium will be accelerated up to a magnetic rigidity of 100 Tm and 300 Tm, respectively. The design of the beam extraction system of both synchrotrons is completed and will be presented in this paper. The extraction devices of both synchrotrons are situated in one common straight section and deflect the beam vertically. SIS100 has been optimized for fast extraction by means of a distributed fast bipolar kicker system. However, slow extraction over a few seconds is also foreseen. SIS300 has been optimized for slow extraction and may generate spills of up to 100s. The slow extraction channel combines horizontal deflection by an electrostatic septum in the first stage with vertical deflection by a Lambertson septum magnet and subsequent magnetic extraction septa in the second stage. An emergency beam dumping system could be integrated in the extraction system of both machines. | ||
| THPP104 | The High Energy Beam Transport System for FAIR | 3608 |
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| The High Energy Beam Transport System of FAIR, with a total length of more than 2350 m, forms a complex system connecting seven accelerator- and storage-rings, the experimental caves, beam dumps, stripping stations, the antiproton target and the Super-FRS. The variety of beams to be transported is considerable, ranging from slow extracted beams with long spills of up to 100 s to short intense bunches with lengths of a few nanoseconds and a momentum spread of up to ±1%. The range of beam intensity covers more than six orders of magnitude. The SIS100/300 rings are located 13.5 m under ground while the rest of the facility is essentially on ground level necessitating a 3-dimensional layout of the beam line system. Most of the beam transport system consists of normal conducting magnets. However, the SIS300 beam line system has to be built with superconducting magnets. Due to the large variety of beam parameters, a careful planning of the beam diagnostics system is important. The paper summarizes the design fundamentals and the current status of the system design. | ||
| THPP105 | Beam Commissioning Results of the RCS Injection and Extraction at J-PARC | 3611 |
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| The beam commissioning of J-PARC (Japan Proton Accelerator Research Complex) 3 GeV RCS (Rapid Cycling Synchrotron) has been started from the end of year 2007. As injection is in the very first stage, an accurate and well controlled beam at the injection strongly related to the other part of the RCS commissioning, including extraction where, an well extracted beam directly reflects the overall commissioning result. In this paper, the beam commissioning results of the RCS injection and extraction will be reported. | ||
| THPP106 | Neutrino Beam Line at J-PARC | 3614 |
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A neutrino beam line for the long baseline neutrino oscillation experiment T2K is under construction at J-PARC in Tokai. Construction is proceeding on schedule and commissioning of the beam line will start in April of 2009. Proton beams are injected from the main ring, then bent about 80 degrees using superconducting magnets directing the beam toward the Super-Kamiokande detector. Muon neutrinos are produced from pions produced at the target. Precise beam tuning is quite important in our beam line since the beam intensity is expected to be 750 kW and failure of the tuning system may cause damage to the beam line components. For this purpose, we install four types of beam monitors in the primary beam line:
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| THPP107 | Lifetime Comparisons of Single and Double Layered HBC-Foils using 3.2MeV Ne+ Ion Beam | 3617 |
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| The Japan-Proton Accelerator Research Complex (J-PARC) requires thick carbon stripper foils of 300-500 μg/cm2 thick to strip electrons from the H-beam supplied by the linac before injection into the RCS. The energy depositions upon foil by the intense circulating proton bunched beam as well as H-beam result in the foil temperature of ~1800K. Thus, conventional carbon stripper foils will rupture in a very short time and even a high quality diamond foil will be broken at around 1800 K. Therfore, thick carbon stripper foils with high durability even at 1800K are indispensable for such accelerators. We have developed HBC (Hybrid type Boron mixed Carbon)-foil. We have measured the lifetime of a double and single-layered HBC-foils, diamond (DM) foils and commercially available carbon (CM) foils for comparisons using 3.2 MeV Ne+ ion beam, in which a significant amount of energy loss is deposited in the foils. The lifetime of the double-layered HBC- foil (180 μg/cm2 x 2) was found to be long 18 and 446 times longer than those of DM-foil (360μg/cm2 x 1) and double-layered CM foils ( 207μg/cm2 x 2), respectively. | ||
| THPP108 | Temperature Measurements of Carbon Stripper Foil by Pulsed 650keV H- Ion Beam | 3620 |
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| Thick carbon foils (>300 mg/cm2) has been used for stripping of H- ion beam at the 3 GeV Rapid Cycling Synchrotron (3GeV-RCS) of the J-PARC. The carbon stripper foils with long lifetime against high temperature >1800 °K are strongly required. We have recently developed a new irradiation system for lifetime measurement using the KEK 650keV Cockcroft-Walton accelerator with high current pulsed and dc H- beams, which can simulate the high-energy deposition upon foils in the RCS. The experimental results from the measured temperature of carbon stripper foil by the pulsed 650keV H- ion beam (-6mApeak, 0.3ms, 25Hz) and the observed time structure in the beam spot by a photo-transistor are described. | ||
| THPP111 | A 250 kHz Chopper for Low Energy High Intensity Proton Beams | 3623 |
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| A neutron pulse with 1 ns pulse length and a repetition rate of 250 kHz is needed for the experiments on nuclear astrophysics using the Frankfurter Neutron source at the Stern-Gerlach-Zentrum. The time structure of the neutron flux is given by the primary proton beam witch hits a 7Li target. The creation of the required time structure on an intense proton beam of 200 mA dc with respect to emittance growth and beam losses is demanding. The pulsing of the ion source depends on the rise time of the plasma whereas the pulsing of the extraction voltage leads into high power deposition into the multi aperture extraction system. On the other hand a chopper system downstream of the RFQ results in rf power consumption due to beam loading and the problem of beam dumping at a beam power of several kW. Therefore it is planed to install a chopper as part of a resonant circuit in the LEBT – section consisting of four solenoids. Two different methods, magnetic and electric deflection, will be discussed with respect to emittance growth, beam losses and the influence on space charge compensation processes. Numerical simulations and preliminary results of experiments will be presented and compared. | ||
| THPP112 | Leakage Field of Septum Magnets of 3 GeV RCS at J-PARC | 3626 |
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| Septum magnets are installed in RCS (Rapid cycling Synchrotron) at J-PARC for the beam injection and extraction. In order to realize MW beam in the RCS ring and reduce the beam loss during the beam injection and extraction, the septum magnets have large physical aperture and are operated in DC. Thus there are high magnetic fields in the gaps during the acceleration, but the leakage fields are nevertheless suppressed down to a few Gauss to suppress the closed orbit distortion. In order to reduce the magnetic leakage field from the septa at beam orbit in the RCS ring, the silicon steel sheets are set for magnetic shield. In addition a few ring vacuum chambers are made by the magnetic stainless steel. Up to now, the development and field measurement of the septum magnets has been finished, and the beam commissioning of the RCS are carried out. In this presentation, the field measurements of the septum magnets are summarized and the influences of the leakage field upon the beam orbit are reported. | ||
| THPP113 | Emittance Growth at LHC Injection from SPS and LHC Kicker Ripple | 3629 |
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| Fast pulsed kicker magnets are used to extract beams from the SPS and inject them into the LHC. The kickers exhibit time-varying structure in the pulse shape which translates into small offsets with respect to the closed orbit at LHC injection. The LHC damper systems will be used to damp out the resulting betatron oscillations, to keep the growth in the transverse emittance within specification. This paper describes the results of the measurements of the kicker ripple for the two systems, both in the laboratory and with beam, and presents the simulated performance of the transverse damper in terms of beam emittance growth. The implications for LHC operation are discussed. |