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Linear lattice modeling of the recycler ring at Fermilab

Description: Substantial differences are found in tunes and beta functions between the existing linear model and the real storage ring. They result in difficulties when tuning the machine to new lattice conditions. We are trying to correct the errors by matching the model into the real machine using Orbit Response Matrix (ORM) Fit method. The challenges with ORM particularly in the Recycler ring and the results are presented in this paper.
Date: June 1, 2006
Creator: Xiao, Meiqin; Valishev, Alexander; Nagaslaev, Vladimir P.; /Fermilab; Sajaev, Vadim & /Argonne
Partner: UNT Libraries Government Documents Department

Measurements and corrections of the Recycler lattice at Fermilab

Description: Obit Response Matrix (ORM) Fit method has been successfully used to calibrate linear optics at Recycler Ring at Fermilab. The linear model of the Recycler optics ring has been significantly improved. Based on the build-up model, lattice measurement of the Recycler ring has been done several times, each after some magnets move and the tunes change. Large beta-wave({approx}20%) has been found in horizontal plane after the working point was moved from (0.424,0.434) to (0.456, 0.467) for the reason of lowering the beam instabilities. The source of the beta-wave, and the correction will be presented in this paper. In addition, we found an easy way to extend the tuning range in the recycler lattice. A new application program for adjusting the tunes operationally was introduced and the measured results will be presented.
Date: July 1, 2008
Creator: Xiao, Meiqin
Partner: UNT Libraries Government Documents Department

Superconducting travelling wave ring with high gradient accelerating section

Description: Use of a superconducting traveling wave accelerating (STWA) structure instead of a standing wave cavity has major advantages in increasing the accelerating gradient in the ILC. In contrast with standing wave cavity STWA requires feedback loop, which sends wave from the structure output to input, making a superconducting traveling wave ring (STWR). One or few input couplers need to excite STWR and compensate power dissipations due to beam loading. To control traveling wave regime in the structure two independent knobs can be used for tuning both resonant ring frequency and backward wave. We discuss two variants of the STWR with one and two feed couplers.
Date: June 1, 2007
Creator: Avrakhov, P. & Solyak, N.
Partner: UNT Libraries Government Documents Department

Test of a coaxial blade tuner at HTS FNAL

Description: A coaxial blade tuner has been selected for the 1.3GHz SRF cavities of the Fermilab SRF Accelerator Test Facility. Results from tuner cold tests in the Fermilab Horizontal Test Stand are presented. Fermilab is constructing the SRF Accelerator Test Facility, a facility for accelerator physics research and development. This facility will contain a total of six cryomodules, each containing eight 1.3 GHz nine-cell elliptical cavities. Each cavity will be equipped with a Slim Blade Tuner designed by INFN Milan. The blade tuner incorporates both a stepper motor and piezo actuators to allow for both slow and fast cavity tuning. The stepper motor allows the cavity frequency to be statically tuned over a range of 500 kHz with an accuracy of several Hz. The piezos provide up to 2 kHz of dynamic tuning for compensation of Lorentz force detuning and variations in the He bath pressure. The first eight blade tuners were built at INFN Milan, but the remainder are being manufactured commercially following the INFN design. To date, more than 40 of the commercial tuners have been delivered.
Date: March 1, 2011
Creator: Pischalnikov, Y.; Barbanotti, S.; Harms, E.; Hocker, A.; Khabiboulline, T.; Schappert, W. et al.
Partner: UNT Libraries Government Documents Department

Tests of a tuner for a 325 MHz SRF spoke resonator

Description: Fermilab is developing 325 MHz SRF spoke cavities for the proposed Project X. A compact fast/slow tuner has been developed for final tuning of the resonance frequency of the cavity after cooling down to operating temperature and to compensate microphonics and Lorentz force detuning [2]. The modified tuner design and results of 4.5K tests of the first prototype are presented. The performance of lever tuners for the SSR1 spoke resonator prototype has been measured during recent CW and pulsed tests in the Fermilab SCTF. The tuner met or exceeded all design goals and has been used to successfully: (1) Bring the cold cavity to the operating frequency; (2) Compensate for dynamic Lorentz force detuning; and (3) Compensate for frequency detuning of the cavity due to changes in the He bath pressure.
Date: March 1, 2011
Creator: Pishchalnikov, Y.; Borissov, E.; Khabiboulline, T.; Madrak, R.; Pilipenko, R.; Ristori, L. et al.
Partner: UNT Libraries Government Documents Department

Low Emittance Tuning Studies for SuperB

Description: SuperB[1] is an international project for an asymmetric 2 rings collider at the B mesons cm energy to be built in the Rome area in Italy. The two rings will have very small beam sizes at the Interaction Point and very small emittances, similar to the Linear Collider Damping Rings ones. In particular, the ultra low vertical emittances, 7 pm in the LER and 4 pm in the HER, need a careful study of the misalignment errors effects on the machine performances. Studies on the closed orbit, vertical dispersion and coupling corrections have been carried out in order to specify the maximum allowed errors and to provide a procedure for emittance tuning. A new tool which combines MADX and Matlab routines has been developed, allowing for both corrections and tuning. Results of these studies are presented.
Date: July 6, 2012
Creator: Liuzzo, Simone; /INFN, Pisa; Biagini, Maria; /INFN, Rome; Raimondi, Pantaleo; /INFN, Rome et al.
Partner: UNT Libraries Government Documents Department

Significant Lifetime and Background Improvements in PEP-II by Reducing the 3rd Order Chromaticity in LER with Orbit Bumps

Description: Orbit bumps in sextupoles are routinely used for tuning the luminosity in the PEP-II B-Factory. Anti-symmetric bumps at a pair of identical sextupoles separated by -I section generate the net dispersion, while symmetric horizontal bumps induce a tune shift and beta beat. By combining two of these symmetric bumps with opposite signs, where the second pair is 90{sup o} away, the tune shift cancels and the beta beat doubles. In the low energy ring (LER), there are four -I sextupole pairs per arc, located one after another 90{sup o} apart, where pairs 1 and 3 are at the same phase and pairs 2 and 4 are 90{sup o} away. By making two symmetric bumps with opposite sign in pairs 1 and 3, the tune shift and beta beat outside this region cancel, but there is a local change of phase and beta in the 2nd sextupole pair located in the middle. By using this bump knob, the LER lifetime improved by a factor of 3, losses by a factor of 5, and the beam-beam background in the drift chamber of the BaBar detector by 20%. Optics analysis showed that the local phase change at the 2nd sextupole pair can compensate the 3rd order chromaticity.
Date: December 18, 2007
Creator: Decker, F.J.; Nosochkov, Y.; Sullivan, M.; Yocky, G. & /SLAC
Partner: UNT Libraries Government Documents Department

Proposal of the Next Incarnation of Accelerator Test Facility at KEK for the International Linear Collider

Description: To reach design luminosity, the International Linear Collider (ILC) must be able to create and reliably maintain nanometer size beams. The ATF damping ring is the unique facility where ILC emittances are possible. In this paper we present and evaluate the proposal to create a final focus facility at the ATF which, using compact final focus optics and an ILC-like bunch train, would be capable of achieving 37 nm beam size. Such a facility would enable the development of beam diagnostics and tuning methods, as well as the training of young accelerator physicists.
Date: May 27, 2005
Creator: Araki, S.; Hayano, H.; Higashi, Y.; Honda, Y.; Kanazawa, K.; Kubo, K. et al.
Partner: UNT Libraries Government Documents Department

Control System Design for Automatic Cavity Tuning Machines

Description: A series of four automatic tuning machines for 9-cell TESLA-type cavities are being developed and fabricated in a collaborative effort among DESY, FNAL, and KEK. These machines are intended to support high-throughput cavity fabrication for construction of large SRF-based accelerator projects. Two of these machines will be delivered to cavity vendors for the tuning of XFEL cavities. The control system for these machines must support a high level of automation adequate for industrial use by non-experts operators. This paper describes the control system hardware and software design for these machines.
Date: May 1, 2009
Creator: Carcagno, R.; Khabiboulline, T.; Kotelnikov, S.; Makulski, A.; Nehring, R.; Nogiec, J. et al.
Partner: UNT Libraries Government Documents Department

Design of 325 MHz single and triple spoke resonators at FNAL

Description: The proposed 8-GeV driver at FNAL is based on approximately 400 independently phased SC resonators. In this paper the design of 325 MHz Spoke Resonators, two single spoke resonators ({beta}=0.22 and {beta}=0.4) and a triple spoke resonator ({beta}=0.62), for the High Intensity Neutrino Source (HINS) front end is presented. We describe the optimization of the spoke resonators geometry, the goal being to minimize the E{sub peak}/E{sub acc} and B{sub peak}/E{sub acc} ratios. We report on the coupled ANSYS-MWS analysis on the resonators mechanical properties and power coupler RF design. The current status of mechanical design, slow tuning mechanism and cryostat are also presented.
Date: August 1, 2006
Creator: Lanfranco, G.; Apollinari, G.; Gonin, I.; Khabiboulline, T.; McConologue, F.; Romanov, G. et al.
Partner: UNT Libraries Government Documents Department

Operational Experiences Tuning the ATF2 Final Focus Optics Towards Obtaining a 37nm Electron Beam IP Spot Size

Description: The primary aim of the ATF2 research accelerator is to test a scaled version of the final focus optics planned for use in next-generation linear lepton colliders. ATF2 consists of a 1.3 GeV linac, damping ring providing low-emittance electron beams (< 12pm in the vertical plane), extraction line and final focus optics. The design details of the final focus optics and implementation at ATF2 are presented elsewhere. The ATF2 accelerator is currently being commissioned, with a staged approach to achieving the design IP spot size. It is expected that as we implement more demanding optics and reduce the vertical beta function at the IP, the tuning becomes more difficult and takes longer. We present here a description of the implementation of the tuning procedures and describe operational experiences and performances.
Date: July 6, 2012
Creator: White, Glen; Seryi, Andrei; Woodley, Mark; Bai, Sha; Bambade, Philip; Renier, Yves et al.
Partner: UNT Libraries Government Documents Department

Linear Collider Test Facility: Twiss Parameter Analysis at the IP/Post-IP Location of the ATF2 Beam Line

Description: At the first stage of the ATF2 beam tuning, vertical beam size is usually bigger than 3 {micro}m at the IP. Beam waist measurements using wire scanners and a laser wire are usually performed to check the initial matching of the beam through to the IP. These measurements are described in this paper for the optics currently used ({beta}{sub x} = 4cm and {beta}{sub y} = 1mm). Software implemented in the control room to automate these measurements with integrated analysis is also described. Measurements showed that {beta} functions and emittances were within errors of measurements when no rematching and coupling corrections were done. However, it was observed that the waist in the horizontal (X) and vertical (Y) plane was abnormally shifted and simulations were performed to try to understand these shifts. They also showed that multiknobs are needed in the current optics to correct simultaneously {alpha}{sub x}, {alpha}{sub y} and the horizontal dispersion (D{sub x}). Such multiknobs were found and their linearity and orthogonality were successfully checked using MAD optics code. The software for these multiknobs was implemented in the control room and waist scan measurements using the {alpha}{sub y} knob were successfully performed.
Date: July 2, 2012
Creator: Bolzon, Benoit; Jeremie, Andrea; Bai, Sha; Bambade, Philip & White, Glen
Partner: UNT Libraries Government Documents Department

Production and Collections of Antiprotons

Description: The historical best antiproton yield obtained at the antiproton source is equal to 1.8 {center_dot} 10{sup -5}. That corresponds to the acceptance of about 17 mm {center_dot} mrad while the largest measured debuncher acceptance is about 25 mm {center_dot} mrad. It is expected that better debuncher tuning will increase the debuncher acceptance to about 35 mm {center_dot} mrad. Thus, improvements of optics and steering in the AP2 line and debuncher should allow an increase of antiproton yield by about 1.7 times to 3.1 {center_dot} 10{sup -5} for 35 mm {center_dot} mrad acceptance as shown in Figure 17. Although the maximum lithium lens gradient, which we can reliably achieve nowadays, is significantly below the optimum we should not expect significant increase of antiproton yield with lens upgrade. To reach the maximum antiproton yield with lens of the same length (15 cm) one would need to increase the lens gradient by 1.4 and 1.7 times correspondingly for 25 and 35 mm {center_dot} mrad acceptances. That corresponds to gradients of 105 and 127 kG/cm reaching of which is a challenging problem. And in spite of this significant increase of focusing strength that will bring only 13% and 16% antiproton yield increases corresponding to acceptances of 25 and 35 mm {center_dot} mrad. Minor improvement of about 3-4% can be achieved comparatively easy by lengthening of the lens by 20-30%.
Date: January 1, 2001
Creator: Lebedev, V.
Partner: UNT Libraries Government Documents Department

Addendum to NuMI shielding assessment

Description: The original safety assessment and the Safety Envelope for the NuMI beam line corresponds to 400 kW of beam power. The Main Injector is currently capable of and approved for producing 500 kW of beam power2. However, operation of the NuMI beam line at 400 kW of power brings up the possibility of an occasional excursion above 400 kW due to better than usual tuning in one of the machines upstream of the NuMI beam line. An excursion above the DOE approved Safety Envelope will constitute a safety violation. The purpose of this addendum is to evaluate the radiological issues and modifications required to operate the NuMI beam line at 500 kW. This upgrade will allow 400 kW operations with a reasonable safety margin. Configuration of the NuMI beam line, boundaries, safety system and the methodologies used for the calculations are as described in the original NuMI SAD. While most of the calculations presented in the original shielding assessment were based on Monte Carlo simulations, which were based on the design geometries, most of the results presented in this addendum are based on the measurements conducted by the AD ES&H radiation safety group.
Date: October 1, 2007
Creator: Vaziri, Kamran
Partner: UNT Libraries Government Documents Department

Lepton Collider Operation With Constant Currents

Description: Electron-positron colliders have been operating in a top-up-and-coast fashion with a cycle time depending on the beam life time, typically one or more hours. Each top-up involves ramping detector systems in addition to the actual filling time. The loss in accumulated luminosity may be 20-50%. During the last year, both B-Factories have commissioned a continuous-injection mode of operation in which beam is injected without ramping the detector, thus raising luminosity integration by always operating at peak luminosity. Constant beam currents also reduce thermal drift and trips caused by change in beam loading. To achieve this level of operation, special efforts were made to reduce the injection losses and also to implement gating procedures in the detectors, minimizing dead time. Beam collimation can reduce injection noise but also cause an increase in background rates. A challenge can be determining beam lifetime, important to maintain tuning of the beams.
Date: February 22, 2006
Creator: Wienands, U.
Partner: UNT Libraries Government Documents Department

Electromagnetic SCRF Cavity Tuner

Description: A novel prototype of SCRF cavity tuner is being designed and tested at Fermilab. This is a superconducting C-type iron dominated magnet having a 10 mm gap, axial symmetry, and a 1 Tesla field. Inside the gap is mounted a superconducting coil capable of moving {+-} 1 mm and producing a longitudinal force up to {+-} 1.5 kN. The static force applied to the RF cavity flanges provides a long-term cavity geometry tuning to a nominal frequency. The same coil powered by fast AC current pulse delivers mechanical perturbation for fast cavity tuning. This fast mechanical perturbation could be used to compensate a dynamic RF cavity detuning caused by cavity Lorentz forces and microphonics. A special configuration of magnet system was designed and tested.
Date: May 1, 2009
Creator: Kashikhin, V.; Borissov, E.; Foster, G.W.; Makulski, A.; Pischalnikov, Y.; Khabiboulline, T. et al.
Partner: UNT Libraries Government Documents Department

Improvement of PEP-II Linear Optics with a MIA-Derived Virtual Accelerator

Description: In several past studies, model independent analysis, in conjunction with a virtual accelerator model, has been successful in improving PEP-II linear geometric optics. In many cases, optics improvement yielded an increase in machine luminosity. In this study, an updated characterization of linear optics is presented. With the PEP-II beam position monitor (BPM) system, four independent beam centroid orbits were extracted and used to determine phase advances and linear Green's functions among BPM locations. A magnetic lattice model was then constructed with a singular value decomposition-enhanced least-square fitting of phase advances and Green's functions, which are functions of quadrupole strengths, sextupole feed-downs, as well as BPM errors, to the corresponding measured quantities. The fitting process yielded a machine model that matched the measured linear optics of the real machine and was therefore deemed the virtual accelerator. High beta beat, as well as linear coupling, was observed in both LER and HER of the virtual accelerator. Since there was higher beta beating in LER, focus was shifted to the improvement of this ring. By adjusting select quadrupoles of the virtual LER and fitting the resulting beta functions and phase advances to those of the desired lattice, the average beta beat of the virtual machine was effectively reduced. The new magnet configuration was dialed into LER on August 10, 2006, and beta beat was reduced by a factor of three. After fine tuning HER to match the improved LER for optimal collision, a record peak luminosity of 12.069 x 10{sup 33} cm{sup -2} s{sup -1} was attained on August 16, 2006.
Date: August 30, 2006
Creator: Cerio, B. & U., /Colgate
Partner: UNT Libraries Government Documents Department

Dual Power Supplies for PEP-II Injection Kickers

Description: Originally the PEP-II injection kickers were powered by one power supply. Since the kicker magnets where not perfectly matched, the stored beam got excited by about 7% of the maximum kicker amplitude. This led to luminosity losses which were especially obvious for trickle injection when the detector is on for data taking. Therefore two independent power supplies with thyratrons in the tunnel next to the kicker magnet were installed. This also reduces the necessary power by about a factor of four since there are no long cables that have to be charged. The kickers are now independently adjustable to eliminate any non-closure of the kicker system and therefore excitation of the stored beam. Setup, commissioning and fine tuning of this system are discussed.
Date: May 25, 2005
Creator: Olszewski, J; Decker, F.-J.; Iverson, R.H.; Kulikov, A.; Pappas, C. & /SLAC
Partner: UNT Libraries Government Documents Department

Development of 325 MHz single spoke resonators at Fermilab

Description: The High Intensity Neutrino Source (HINS) project represents the current effort at Fermilab to produce an 8-GeV proton linac based on 400 independently phased superconducting cavities. Eighteen ?=0.21 single spoke resonators, operating at 325 MHz, comprise the first stage of the linac cold section. In this paper we present the current status of the production and testing of the first two prototype cavities. This includes descriptions of the fabrication, frequency tuning, chemical polishing, high pressure rinse, and high-gradient cold tests.
Date: August 1, 2008
Creator: Apollinari, G.; Gonin, I.V.; Khabiboulline, T.N.; Lanfranco, G.; Mukherjee, A.; Ozelis, J. et al.
Partner: UNT Libraries Government Documents Department

Status of the ATF2 Lattices

Description: The current status for the ATF2 Nominal and Ultra-low {beta}* lattices are presented in this paper. New lattice designs have been obtained in order to minimise the impact of the last interpretation of multipole measurements that have been included into the model. However, the new ATF2 Ultra-low design is not able to recover the expected vertical beam size at the IP with the current magnet distribution. Therefore, different quadrupole sorting have been studied. A significant gain is evident for the ATF2 Ultra-low lattice when sorting the magnets according to the skew-sextupolar components. The ATF2 Nominal lattice is also expected to benefit from the new sorting. Tuning results of the new ATF2 Ultra-low lattice under realistic imperfections are also reported.
Date: December 9, 2011
Creator: Marin, E.; Tomas, R.; /CERN; Bambade, P.; /Orsay, LAL; Okugi, T. et al.
Partner: UNT Libraries Government Documents Department

Operating Procedure Changes to Improve Antiproton Production at the Fermilab Tevatron Collider

Description: Since the start of Fermilab Collider Run II in 2001, the maximum weekly antiproton accumulation rate has increased from 400 x 10{sup 10} Pbars/week to approximately 3,700 x 10{sup 10} 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 the beam line orbit control, stochastic cooling power level management, and RF settings. In addition, daily tuning efforts have been streamlined by implementing sequencer driven tuning software.
Date: April 1, 2009
Creator: Drendel, B.; Morgan, J.P.; Vander Meulen, D. & /Fermilab
Partner: UNT Libraries Government Documents Department

A technique for monitoring fast tuner piezoactuator preload forces for superconducting rf cavities

Description: The technology for mechanically compensating Lorentz Force detuning in superconducting RF cavities has already been developed at DESY. One technique is based on commercial piezoelectric actuators and was successfully demonstrated on TESLA cavities [1]. Piezo actuators for fast tuners can operate in a frequency range up to several kHz; however, it is very important to maintain a constant static force (preload) on the piezo actuator in the range of 10 to 50% of its specified blocking force. Determining the preload force during cool-down, warm-up, or re-tuning of the cavity is difficult without instrumentation, and exceeding the specified range can permanently damage the piezo stack. A technique based on strain gauge technology for superconducting magnets has been applied to fast tuners for monitoring the preload on the piezoelectric assembly. The design and testing of piezo actuator preload sensor technology is discussed. Results from measurements of preload sensors installed on the tuner of the Capture Cavity II (CCII)[2] tested at FNAL are presented. These results include measurements during cool-down, warmup, and cavity tuning along with dynamic Lorentz force compensation.
Date: June 1, 2007
Creator: Pischalnikov, Y.; Branlard, J.; Carcagno, R.; Chase, B.; Edwards, H.; Orris, D. et al.
Partner: UNT Libraries Government Documents Department

Modifications of the LCLS Photoinjector Beamline

Description: The LCLS Photoinjector beamline is now in the Design and Engineering stage. The fabrication and installation of this beamline is scheduled for the summer 2006. The Photoinjector will deliver 10 ps long electron bunches of 1nC with a normalized transverse emittance of less than 1 mm.mrad for 80% of the slices constituting the core of the bunch at 135 MeV. The calculations done to finalize the specifications of the photoinjector beamline components are described. Modifications include a new exit energy, additional focusing between the two linac modules, the insertion of a ''laser heater'', and a new geometry for the coupling cells of the RF structures. We also discuss two interesting tunings, one for the nominal charge of 1nC but using a longer laser pulse and the second one for a lower charge of 0.2nC. Sensitivity to field errors and misalignment for those two new configurations is compared to that of the nominal tuning.
Date: May 9, 2005
Creator: Dowell, D.; Gierman, S.M.; Limborg-Deprey, C. & /SLAC
Partner: UNT Libraries Government Documents Department

Trickle-Charge: a New Operational Mode for PEP-II

Description: In regular top-up-and-coast operation, PEP-II average luminosity is about 70-75% of the peak luminosity due to detector ramp-down and ramp-up times plus the time it takes to top-up both beams. We recently commissioned a new operational mode where the Low Energy Ring is injected continuously without ramping down the detector. The benefits--increased luminosity lifetime and roughly half the number of top-ups per shift--were expected to give an increase in delivered luminosity of about 15% at the same peak luminosity; this was confirmed in test runs. In routine trickle operation, however, it appears that the increase in delivered luminosity is more than twice that due to an increase in availability credited to the more stable operating conditions during trickle operation. Further gains were made when continuous injection was extended to the high energy ring as well. In this paper we will present our operational experience as well as some of the diagnostics we use to monitor and maintain tuning of the machine in order to control injection background and protect the detector.
Date: May 9, 2005
Creator: Kozanecki, W.; Colocho, W. S.; Decker, F. -J.; Ecklund, S.; Fisher, A. S.; Iverson, R. H. et al.
Partner: UNT Libraries Government Documents Department