Fermilab, Batavia
Funding: Work supported by the U.S. Department of Energy under contract No. DE-AC02-76CH03000
Steady growth of luminosity has been demonstrated during the entire Tevatron Run II culminating in a record Tevatron performance. During last two years the major contributions came from improvements in antiproton stacking and cooling as well as from numerous improvements in the Tevatron. The talk will describe these improvements as well as other unexpected problems which were encountered and resolved on the road to this success.
Fermilab, Batavia
Funding: Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359 with the United States Department of Energy.
We present the strategy which has been used recently to optimize integrated luminosity at the Fermilab Tevatron proton-antiproton collider. We use a relatively simple model where we keep the proton intensity fixed, use parameters from fits to the luminosity decay of recent stores as a function of initial antiproton intensity (stash size), and vary the stash size to optimize the integrated luminosity per week. The model assumes a fixed rate of antiproton production, that a store is terminated as soon as the target stash size for the next store is reached, and that the only downtime is due to store turn-around time. An optimal range of stash size is predicted. Since the start of Tevatron operations based on this procedure we have seen an improvement of approximately 35% in integrated luminosity. Other recent operational improvements have been achieved by decreasing the shot setup time and by reducing beam-beam effects by making the proton and antiproton brightnesses more compatible , for example by scraping protons to smaller emittances.
GSI, Darmstadt
To feed the production targets of FAIR with very short bunches (pulse durations of not more than 50 ns are envisaged) demanding rf-systems for bunch compression are required in SIS18 and SIS100. But also the opposite process, namely debunching, is required in the collector ring CR. Bunch compression as well as debunching will be done by fast bunch rotation. Due to space restrictions both rf-systems must be able to generate a very high field gradient of 50 kV/m at very low frequencies. Such high field gradients can be realised only using magnetic alloy (MA) cavities, since their saturation field strength is about ten times higher compared to NiZn-ferrites. For SIS18 a MA bunch compressor unit, which generates the required 50 kV/m at 800- and 1200 kHz, has already been realized as a forerunner for the required FAIR-systems.
GSI, Darmstadt
Laboratoire de Physique des Gaz et des Plasmas, Universite Paris-Sud, Orsay
IPCP, Chernogolovka, Moscow region
TU Darmstadt, Darmstadt
Universidad de Castilla-La Mancha, Ciudad Real
Studies of High Energy Density (HED) states in matter is one of the recently proposed important applications of intense particle beams. GSI Darmstadt is worldwide famous due to its unique accelerator facilities. Construction of the new accelerator FAIR, will enhance these capabilities many fold. During the past years, extensive theoretical work has been carried out to propose future HED physics experiments that could be carried out at FAIR. It is expected that the new heavy ion synchrotron, SIS100, will deliver a uranium beam with 1012 uranium ions that will be delivered in a single bunch, 50 – 100 ns long. Circular, elliptic and annular focal spots can be generated that will allow one to perform different type of HED physics experiments. This work has shown that using a special technique, named HIHEX, one may access those areas of the phase diagram that have never been accessed before. Using another experimental configuration, LAPLAS , it will be possible to generate physical conditions that are expected to exist in the interiors of the giant planets. Material properties under dynamic conditions can also be studied using a third experimental set up.
Fermilab, Batavia
The multi-batch slip stacking has been used for operation since January, 2008 and effectively increased proton intensity to the NuMI target by 50% in a MI cycle. The MI accepts 11 pulses at injection energy from the Booster and sends two pulses to Anti-proton production and nine to the NuMI beam line. The total beam power on a cycle was increased to 340 KW on average. We have been doing beam studies in order to increase the beam power to 400 kW and to control the beam loss. We also discuss 12 batch slip stacking scheme which is going to be used for future Neutrino experiments.
Fermilab, Batavia
Run II has been ongoing since 2001. Peak luminosities in the Tevatron have increased from approximately 10×1030 cm-2ses-1 to 300×1030 cm-2ses-1 a factor of 30 improvement. A significant contributing factor in this remarkable progress is a greatly improved antiproton production capability. Since the beginning of Run II, the average antiproton accumulation rate has increased from 2×1010 p/hr to about 24×1010 p/hr. Peak antiproton stacking rates presently exceed 25×1010 p/hr. The antiproton stacking rate has nearly doubled in the last two years alone. A variety of improvements have contributed to the recent progress in antiproton production. The process of transferring antiprotons to the Recycler Ring for subsequent transfer to the collider has been significantly restructured and streamlined, allowing more time to be utilized for antiproton production. Improvements to the target station have greatly increased the antiproton yield from the production target. The performance of the Antiproton Source stochastic cooling systems has been enhanced by improvements to the cooling electronics, accelerator lattice optimization, and improved operating procedures.
Fermilab, Batavia
Funding: Operated by Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359 with the United States Department of Energy
Antiprotons in Fermilab’s Recycler ring are cooled by a 4.3 MeV, 0.1A DC electron beam as well as by a stochastic cooling system. In this paper we will describe electron cooling improvements recently implemented: adjustments of electron beam line quadrupoles to decrease the electron angles in the cooling section and a better stabilization and control of the electron energy.
FZJ, Jülich
CNS, Saitama
CERN, Geneva
The High Energy Storage Ring (HESR) of the future International Facility for Antiproton and Ion Research (FAIR) at the GSI in Darmstadt will be built as an anti-proton cooler ring in the momentum range from 1.5 to 15 GeV/c. An important and challenging feature of the new facility is the combination of phase space cooled beams with internal targets. In addition to electron cooling transverse and longitudinal stochastic cooling are envisaged to accomplish these goals. A detailed numerical analysis of the Fokker-Planck equation for longitudinal filter and time-of-flight cooling including an internal target and intrabeam scattering has been carried out to demonstrate the stochastic cooling capability. Model predictions have been compared to experimental cooling results with internal targets at the COSY facility. Experimental results at COSY to compensate the large mean energy loss induced by an internal Pellet target similar to that being used by the PANDA experiment at the HESR with a barrier bucket cavity (BB) will be presented. Experimental tests of stochastic filter cooling with internal target and BB operation as well as expected cooling properties for the HESR are discussed.
Fermilab, Batavia
Funding: Operated by Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359 with the United States Department of Energy.
Since 2005, the Recycler has become the sole storage ring for antiprotons used in the Tevatron Collider. The operational role of the Antiproton Source has shifted exclusively towards producing antiprotons for periodic transfers to the Recycler. The process of transferring the antiprotons from the Accumulator to the Recycler has been greatly improved, leading to a dramatic reduction in the transfer time. The reduction in time has been accomplished with a net improvement in transfer efficiency and an increase in average stacking rate. This paper will describe the software improvements that streamlined the transfer process and other changes that contributed to a significant increase in the number of antiprotons available to the Collider.
Fermilab, Batavia
Funding: Operated by Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359 with the United States Department of Energy.
The recent record-setting performance of the Fermilab Tevatron is the culmination of a long series of efforts to optimize the many parameters that go into generating integrated luminosity for the colliding beams experiments. While several complex numerical computer models exist that are used to help optimize the performance of the Tevatron collider program, here we take an analytical approach in an attempt to illustrate the most fundamental aspects of integrating luminosity in the Tevatron. The essential features, such as weekly integrated luminosity and store length optimization, can be understood in a transparent way from basic operational parameters such as antiproton stacking rate and observed beam emittance growth rates in the Tevatron. Comparisons of the analytical model with operational data are provided.
Fermilab, Batavia
Funding: Work supported by the United States Department of Energy under Contract No. DE-AC02-07CH11359
Significant difference in transverse size of the proton and antiproton bunches at collision points is known to cause deterioration of the larger (proton) beam life time at Tevatron. The reason is believed to be in the combination of large betatron tune spread induced by the high nonlinearity of the beam-beam force, and limited tune space. We consider the prospects for application of hollow electron beam for beam-beam tune spread suppression.
Fermilab, Batavia
The proposed Mu2e experiment will present a number of challenges for the Fermilab accelerator complex. The Accumulator and Debuncher rings of what is currently the antiproton complex will be required to handle proton beams with intensities several orders of magnitude larger than the antiproton beams they now carry, leading to a substantial space-charge tune shift. The protons will be then be extracted from the Debuncher using resonant extraction. We present results from simulations of 3D space charge effects for Mu2e beam parameters, with emphasis on how they affect the resonant extraction process.
GSI, Darmstadt
JINR, Dubna, Moscow Region
Electroplant, Moscow
TUG/ITP, Graz
IHEP Protvino, Protvino, Moscow Region
The first full size superconducting dipole magnets for the SIS 100 Tm synchrotron were built and tested. The achieved magnetic field has been measured with a rotating coil probe. An intensive Finite Element R&D, necessitated by the used superconducting cable as well as by the complex mechanical coil and yoke structure, allows calculating the field with high accuracy. Elliptic multipoles were used to describe the field within the whole aperture of the vacuum chamber. As the final design for the SIS 100 dipoles is curved, we developed toroidal multipoles describing the field within a curved magnet, and enabling us to interpret the measurement of a rotating coil probe within such magnets. We describe the performance of the magnetic measurement system, present the measured field properties and compare them to the calculated ones.
GSI, Darmstadt
The FAIR Storage Rings (CR, RESR and NESR) are designed for efficient cooling, accumulation, deceleration and performing nuclear physics experiments with antiproton and rare isotopes beams. Tracking studies for all these rings have been performed to estimate the dynamic aperture and other properties of beam stability depending on the low and high field multipole components, fringe fields and field interference. The multipole limits have to be determined in order to provide a reasonable estimate of the stability boundary and needed correction of the low field multipoles. We report on quantitative studies of the effects of multipoles on the dynamic aperture of the rings, and show that the systematic multipole components in the present magnet designs are unlikely to impose a severe limitation.
The University of Liverpool, Liverpool
Cockcroft Institute, Warrington, Cheshire
MPI-K, Heidelberg
Funding: Work supported by the Helmholtz Association of National Research Centers (HGF) under contract number VH-NG-328 and GSI Helmholtzzentrum für Schwerionenforschung GmbH.
The novel electrostatic Ultra-low energy Storage Ring (USR), planned to be installed at the future Facility for Low-energy Antiproton and Ion Research (FLAIR), will slow down antiprotons and possibly highly charged ions down to 20 keV/q. This multipurpose machine puts challenging demands on the necessary beam instrumentation. Ultra-short bunches (1-2 ns) on the one hand and a quasi-DC beam structure on the other, together with a variable very low beam energies (20-300 keV/q), ultra-low currents (down to 1 nA or even less for a non-circulating beam) and few particles (< 2x107), require the development of new diagnostic devices as most of the standard techniques are not suitable. Several solutions, like resonant capacitive pick-ups, beam profile monitors, Faraday cups or cryogenic current comparators, are under consideration. This contribution presents the beam instrumentation foreseen for the USR.
Fermilab, Batavia
Funding: Work supported by the United States Department of Energy under Contract No. DE-AC02-07CH11359
Over the past year Tevatron has been routinely operating at initial luminosity over 3·1032. The high luminosity regime highlighted several issues that became the focus for operational improvements. In this report we summarize the experience in such areas as mitigation of particle losses, maintaining orbit and optics stability, and identification of aperture restrictions.
GSI, Darmstadt
CERN, Geneva
The FAIR storage ring complex comprises three storage rings with a magnetic rigidity of 13 m. Each of the rings, CR, RESR, and NESR, serves specific tasks in the preparation of secondary beams, rare isotopes and antiprotons, or for experiments with heavy ion beams. The CR is optimized for fast stochastic pre-cooling of secondary beams. The RESR design includes optimization of antiproton accumulation. The design of the NESR for experiments with heavy ions, deceleration of ions or antiprotons for a subsequent low energy facility, and the accumulation of rare isotope beams is proceeding. This report summarizes various new concepts conceived in the design process of this new storage ring facility.
MPI-K, Heidelberg
Cockcroft Institute, Warrington, Cheshire
Funding: Work supported by the Helmholtz Association of National Research Centers (HGF) under contract number VH-NG-328 and GSI Helmholtzzentrum für Schwerionenforschung GmbH
In the future Facility for Low-energy Antiproton and Ion Research (FLAIR) at GSI, the Ultra-low energy electrostatic Storage Ring (USR) will provide cooled beams of antiprotons and possibly also highly charged ions down to energies of 20 keV/q. A large variety of the envisaged experiments demands a very flexible ring lattice to provide a beam with variable cross section, shape and time structure, ranging from ultra-short pulses to coasting beams. The preliminary design of the USR worked out in 2005 was not optimized in this respect and had to be reconsidered. In this contribution we present the final layout of the USR with a focus on its “split-achromat” geometry, the combined fast/slow extraction, and show the different modes of operation required for electron cooling, internal experiments, or beam extraction. We finally give a summary of the machine parameters and the layout of the optical elements.
Fermilab, Batavia
Funding: Operated by Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359 with the United States Department of Energy
Since the start of Fermilab Collider Run II in 2001, the maximum weekly antiproton accumulation rate has increased from 400·1010 Pbars/week to approximately 3,700·1010 Pbars/week. There are many factors contributing to this increase, one of which involves changes to operational procedures that have streamlined and automated antiproton source production. Automation has been added to our beam line orbit control, stochastic cooling power level management, and RF settings. In addition, daily tuning efforts have been streamlined by implementing sequencer driven aggregates.
MPI-K, Heidelberg
Cockcroft Institute, Warrington, Cheshire
Funding: Work supported by the Helmholtz Association of National Research Centers (HGF) under contract number VH-NG-328 and GSI Helmholtzzentrum für Schwerionenforschung GmbH.
One of the central goals of the Ultra-Low energy Storage Ring (USR) project within the future Facility for Low-energy Antiproton and Ion Research (FLAIR) is to provide very short bunches in the 1-2 nanosecond regime to pave the way for kinematically complete measurements of the collision dynamics of fundamental few-body quantum systems for the first time on the level of differential cross sections. The “short pulse” operation mode may be split up in two steps: First, the cooled coasting beam of low energy ions will be adiabatically captured by a high harmonic RF cavity (20 MHz) into ~50 ns buckets. Second, the beam will be compressed to very short pulses with a desired width of only 1-2 ns by an RF buncher located 2 m in front of the so-called reaction microscope. To efficiently limit the beam energy spread, RF decompression is then done at after the experiment to avoid beam losses. In this contribution, we present numerical investigations of this very particular operation mode.