26 Matching Results

Search Results

Advanced search parameters have been applied.

Using the transverse digital damper as a real-time tune monitor for the Booster synchrotron at Fermilab

Description: The Fermilab Booster is a fast ramping (15Hz) synchrotron which accelerates protons from 400MeV to 8GeV. During commissioning of a transverse digital damper system, it was shown that the damper could provide a measurement of the machine tune throughout the cycle by exciting just 1 of the 84 bunches with minimal impact on the machine operation. The algorithms used to make the measurement have been incorporated into the damper FPGA firmware allowing for real-time tune monitoring of all Booster cycles. A new Booster tune monitor was implemented in the digital damper which has minimal impact on the Booster operation. The tune measures the tunes in two planes over the energy ramping cycle with an accuracy of 0.01 in real time.
Date: August 1, 2011
Creator: Eddy, N. & Lysenko, O.
Partner: UNT Libraries Government Documents Department

Wire Position Monitoring with FPGA based Electronics

Description: This fall the first Tesla-style cryomodule cooldown test is being performed at Fermilab. Instrumentation department is preparing the electronics to handle the data from a set of wire position monitors (WPMs). For simulation purposes a prototype pipe with a WMP has been developed and built. The system is based on the measurement of signals induced in pickups by 320 MHz signal carried by a wire through the WPM. The wire is stretched along the pipe with a tensioning load of 9.07 kg. The WPM consists of four 50 {Omega} striplines spaced 90{sup o} apart. FPGA based digitizer scans the WPM and transmits the data to a PC via VME interface. The data acquisition is based on the PC running LabView. In order to increase the accuracy and convenience of the measurements some modifications were required. The first is implementation of an average and decimation filter algorithm in the integrator operation in the FPGA. The second is the development of alternative tool for WPM measurements in the PC. The paper describes how these modifications were performed and test results of a new design. The last cryomodule generation has a single chain of seven WPMs (placed in critical positions: at each end, at the three posts and between the posts) to monitor a cold mass displacement during cooldown. The system was developed in Italy in collaboration with DESY. Similar developments have taken place at Fermilab in the frame of cryomodules construction for SCRF research. This fall preliminary cryomodule cooldown test is being performed. In order to prepare an appropriate electronic system for the test a prototype pipe with a WMP has been developed and built, figure 1. The system is based on the measurement of signals induced in pickups by 320 MHz signal carried by a wire through the WPM. The 0.5 ...
Date: January 1, 2009
Creator: Eddy, N. & Lysenko, O.
Partner: UNT Libraries Government Documents Department

Transverse digital damper system for the Fermilab anti-proton recycler

Description: A transverse damping system is used in the Recycler at Fermilab to damp beam instabilities which arise from large beam intensities with electron cooling. Initial tests of electron cooling demonstrated beam loss due to transverse beam motion when the beam was cooled past the beam density threshold. The transverse damper system consists of two horizontal and two vertical pickups whose signals are amplified and passed into an analog hybrid to generate a difference signal from each pickup. The difference signals are input to a custom digital damper board which digitizes the analog signals at 212mhz, performs digital processing of the signals inside a large Altera Stratix II FPGA, then provides analog output at 212mhz via digital to analog converters. The digital damper output is sent to amplifiers which drive one horizontal and one vertical kicker. An initial prototype digital damper board has been successfully used in the Recycler for over six months. Currently, work is underway to replace the prototype board with an upgraded VME version.
Date: May 1, 2006
Creator: Eddy, N. & Crisp, J.
Partner: UNT Libraries Government Documents Department

GRAIN REFINEMENT OF URANIUM BY ALLOYING

Description: Binary alloys of uranium with 38 elements in the range 0.01 to 1.0 at.% were made. Three alloys havirg nominal compositions of 0.01, 0.1, and 1.0 at.% were made with most of the elements, and in addition, 12 ternary and quaternary alloys were made. The alloys were cast, rolled to 7/8-inch-diameter bars, heat treated, and examined for grain size. (auth)
Date: June 1, 1951
Creator: Saller, H.A.; Keeler, J.R. & Eddy, N.S.
Partner: UNT Libraries Government Documents Department

A Wire Position Monitor System for the 1.3 FHZ Tesla-Style Cryomodule at the Fermilab New-Muon-Lab Accelerator

Description: The first cryomodule for the beam test facility at the Fermilab New-Muon-Lab building is currently under RF commissioning. Among other diagnostics systems, the transverse position of the helium gas return pipe with the connected 1.3 GHz SRF accelerating cavities is measured along the {approx}15 m long module using a stretched-wire position monitoring system. An overview of the wire position monitor system technology is given, along with preliminary results taken at the initial module cooldown, and during further testing. As the measurement system offers a high resolution, we also discuss options for use as a vibration detector. An electron beam test facility, based on superconducting RF (SRF) TESLA-style cryomodules is currently under construction at the Fermilab New-Muon-Lab (NML) building. The first, so-called type III+, cryomodule (CM-1), equipped with eight 1.3 GHz nine-cell accelerating cavities was recently cooled down to 2 K, and is currently under RF conditioning. The transverse alignment of the cavity string within the cryomodule is crucial for minimizing transverse kick and beam break-up effects, generated by the high-order dipole modes of misaligned accelerating structures. An optimum alignment can only be guaranteed during the assembly of the cavity string, i.e. at room temperatures. The final position of the cavities after cooldown is uncontrollable, and therefore unknown. A wire position monitoring system (WPM) can help to understand the transverse motion of the cavities during cooldown, their final location and the long term position stability after cryo-temperatures are settled, as well as the position reproducibility for several cold-warm cycles. It also may serve as vibration sensor, as the wire acts as a high-Q resonant detector for mechanical vibrations in the low-audio frequency range. The WPM system consists out of a stretched-wire position detection system, provided with help of INFN-Milano and DESY Hamburg, and RF generation and read-out electronics, developed at Fermilab.
Date: August 17, 2011
Creator: Eddy, N.; Fellenz, B.; Prieto, P.; Semenov, A.; Voy, D.C.; Wendt, M. et al.
Partner: UNT Libraries Government Documents Department

Creep Strength of Uranium Alloys at 1500 and 1800 F

Description: Abstract:"The creep resistance of various uranium binary alloys was investigated at 1500 and 1800 F in vacuum. Tests were made on alloys of uranium with beryllium, columbium, molybdenum, tantalum, titanium, and zirconium and on molybdenum-UO2 composites. Of the alloys examined, those of the uranium-molybdenum system exhibited the best creep resistance. At 1500 F, creep rates of about 0.005%/hr were produced in uranium-molybdenum alloys by a stress of 2500 psi and, at 1800 F, similar creep rates were obtained in composites of 90 wt % molybdenum-10 wt % UO2 by a stress of 12,000 psi."
Date: May 28, 1953
Creator: Saller, Henry A.; Stacy, J. T.; Eddy, N. S. & Klebanow, H. L.
Partner: UNT Libraries Government Documents Department

The Ductility of Brazed Stainless Steel Joints

Description: Abstract: "The ductility of Type 310 stainless steel T-joints brazed with GE-62 brazing alloy was measured at room temperatures 1200, 1650, and 1800 F. The measure of ductility was taken as the plastic axial strain required to crack braze fillets in T-section tensile specimens. At elevated temperatures, the ductility of as-brazed joints approximated that of the stainless steel, but at room temperature the brazed joints had only one-tenth the ductility of the base metal. Annealing for 16 hr at 1800 F in air was found to triple the room-temperature ductility of the brazed joint."
Date: July 8, 1953
Creator: Saller, Henry A.; Stacy, J. T. & Eddy, N. S.
Partner: UNT Libraries Government Documents Department

Grain Refinement of Uranium by Alloying

Description: Binary alloys of uranium with 38 elements in the range 0.01 to 1.0 at.% were made. Three alloys having nominal compositions of 0.01, 0.1, and 1.0 at.% were made with most of the elements, and in addition, 12 ternary and quaternary alloys were made. The alloys were cast, rolled to 7/8-inch-diameter bars, heat treated, and examined for grain size.
Date: June 1, 1951
Creator: Saller, Henry A.; Keeler, J. R. & Eddy, N. S.
Partner: UNT Libraries Government Documents Department

Transverse Instabilities in the Fermilab Recycler

Description: Transverse instabilities of the antiproton beam have been observed in the Recycler ring soon after its commissioning. After installation of transverse dampers, the threshold for the instability limit increased significantly but the instability is still found to limit the brightness of the antiprotons extracted from the Recycler for Tevatron shots. In this paper, we describe observations of the instabilities during the extraction process as well as during dedicated studies. The measured instability threshold phase density agrees with the prediction of the rigid beam model within a factor of 2. Also, we conclude that the instability threshold can be significantly lowered for a bunch contained in a narrow and shallow potential well due to effective exclusion of the longitudinal tails from Landau damping.
Date: July 1, 2011
Creator: Prost, L.R.; Burov, A.; Shemyakin, A.; Bhat, C.M.; Crisp, J.; Eddy, N. et al.
Partner: UNT Libraries Government Documents Department

Transverse instability of the antiproton beam in the Recycler Ring

Description: The brightness of the antiproton beam in Fermilab's 8 GeV Recycler ring is limited by a transverse instability. This instability has occurred during the extraction process to the Tevatron for large stacks of antiprotons even with dampers in operation. This paper describes observed features of the instability, introduces the threshold phase density to characterize the beam stability, and finds the results to be in agreement with a resistive wall instability model. Effective exclusion of the longitudinal tails from Landau damping by decreasing the depth of the RF potential well is observed to lower the threshold density by up to a factor of two.
Date: March 1, 2011
Creator: Prost, L.R.; Bhat, C.M.; Burov, A.; Crisp, J.; Eddy, N.; Hu, M. et al.
Partner: UNT Libraries Government Documents Department

Observation of Instabilities of Coherent Transverse Ocillations in the Fermilab Booster

Description: The Fermilab Booster - built more than 40 years ago - operates well above the design proton beam intensity of 4 {center_dot} 10{sup 12} ppp. Still, the Fermilab neutrino experiments call for even higher intensity exceeding 5.5 {center_dot} 10{sup 12} ppp. A multitude of intensity related effects must be overcome in order to meet this goal including suppression of coherent dipole instabilities of transverse oscillations which manifest themselves as a sudden drop in the beam current. In this report we present the results of observation of these instabilities at different tune, coupling and chromaticity settings and discuss possible cures.
Date: May 1, 2012
Creator: Alexahin, Y.; Eddy, N.; Gianfelice-Wendt, E.; Lebedev, V.; Marsh, W.; Pellico, W. et al.
Partner: UNT Libraries Government Documents Department

High resolution BPMS with integrated gain correction system

Description: High resolution beam position monitors (BPM) are an essential tool to achieve and reproduce a low vertical beam emittance at the KEK Accelerator Test Facility (ATF) damping ring. The ATF damping ring (DR) BPMs are currently upgraded with new high resolution read-out electronics. Based on analog and digital down-conversion techniques, the upgrade includes an automatic gain calibration system to correct for slow drift effects and ensure high reproducible beam position readings. The concept and its technical realization, as well as preliminary results of beam studies are presented.
Date: August 1, 2009
Creator: Wendt, M.; Briegel, C.; Eddy, N.; Fellenz, B.; Gianfelice, E.; Prieto, P. et al.
Partner: UNT Libraries Government Documents Department

High Resolution BPM Upgrade for the ATF Damping Ring at KEK

Description: A beam position monitor (BPM) upgrade at the KEK Accelerator Test Facility (ATF) damping ring has been accomplished, carried out by a KEK/FNAL/SLAC collaboration under the umbrella of the global ILC R&D effort. The upgrade consists of a high resolution, high reproducibility read-out system, based on analog and digital down-conversion techniques, digital signal processing, and also implements a new automatic gain error correction schema. The technical concept and realization as well as results of beam studies are presented. The next generation of linear colliders require ultra-low vertical emittance of <2 pm-rad. The damping ring at the KEK Accelerator Test Facility (ATF) is designed to demonstrate this mission critical goal. A high resolution beam position monitor (BPM) system for the damping ring is one of the key tools for realizing this goal. The BPM system needs to provide two distnict measurements. First, a very high resolution ({approx}100-200nm) closed-orbit measurement which is averaged over many turns and realized with narrowband filter techniques - 'narrowband mode'. This is needed to monitor and steer the beam along an optimum orbit and to facilitate beam-based alignment to minimize non-linear field effects. Second, is the ability to make turn by turn (TBT) measurements to support optics studies and corrections necessary to achieve the design performance. As the TBT measurement necessitates a wider bandwidth, it is often referred to as 'wideband mode'. The BPM upgrade was initiated as a KEK/SLAC/FNAL collaboration in the frame of the Global Design Initiative of the International Linear Collider. The project was realized and completed using Japan-US funds with Fermilab as the core partner.
Date: August 17, 2011
Creator: Eddy, N.; Briegel, C.; Fellenz, B.; Gianfelice-Wendt, E.; Prieto, P.; Rechenmacher, R. et al.
Partner: UNT Libraries Government Documents Department

Using higher order modes in superconducting accelerating cavities for beam monitoring

Description: Dipole modes have been shown to be successful diagnostics for the beam position in superconducting accelerating cavities at the Free Electron Laser in Hamburg (FLASH) facility at DESY. By help of downmixing electronics the signals from the two higher order mode (HOM) couplers mounted on each cavity are monitored. The calibration, based on sigular value decomposition, is more complicated than in standard position monitors. Position like signals based on this calibration are currently being in the process of being included in the control system. A second setup based on digitizing the spectrum from the HOM couplers has been used for monitoring monopole modes. The beam phase with respect to the RF has been thus monitored. The position calibration measurements and phase monitoring made at the FLASH are presented.
Date: January 1, 2006
Creator: Molloy, S.; Baboi, N.; Eddy, N.; Frisch, J.; Hendrickson, L.; Hensler, O. et al.
Partner: UNT Libraries Government Documents Department

Investigations of the Wideband Spectrum of Higher Order Modes Measured on TESLA-style Cavities at the FLASH Linac

Description: Higher Order Modes (HOMs) excited by the passage of the beam through an accelerating cavity depend on the properties of both the cavity and the beam. It is possible, therefore, to draw conclusions on the inner geometry of the cavities based on observations of the properties of the HOM spectrum. A data acquisition system based on two 20 GS/s, 6 GHz scopes has been set up at the FLASH facility, DESY, in order to measure a significant fraction of the HOM spectrum predicted to be generated by the TESLA cavities used for the acceleration of its beam. The HOMs from a particular cavity at FLASH were measured under a range of known beam conditions. The dipole modes have been identified in the data. 3D simulations of different manufacturing errors have been made, and it has been shown that these simulations can predict the measured modes.
Date: June 27, 2007
Creator: Molloy, S.; Adolphsen, C.; Bane, K.; Frisch, J.; Li, Z.; May, J. et al.
Partner: UNT Libraries Government Documents Department

Status of antiproton accumulation and cooling at Fermilab's Recycler

Description: The Recycler ring is an 8 GeV permanent magnet storage ring where antiprotons are accumulated and prepared for Fermilab's Tevatron Collider program. With the goal of maximizing the integrated luminosity delivered to the experiments, storing, cooling and extracting antiprotons with high efficiency has been pursued. Over the past two years, while the average accumulation rate doubled, the Recycler continued to operate at a constant level of performance thanks to changes made to the Recycler Electron Cooler (energy stability and regulation, electron beam optics), RF manipulations and operating procedures. In particular, we discuss the current accumulation cycle in which {approx} 400 x 10{sup 10} antiprotons are accumulated and extracted to the Tevatron every {approx}15 hours.
Date: August 1, 2009
Creator: Prost, L.R.; Bhat, C.M.; Broemmelsiek, D.; Burov, A.; Carlson, K.; Crisp, J. et al.
Partner: UNT Libraries Government Documents Department

High Precision Superconducting Cavity Diagnostics With Higher Order Mode Measurements

Description: Experiments at the FLASH facility at DESY have demonstrated that the higher order modes induced in superconducting cavities can be used to provide a variety of beam and cavity diagnostics. The axes of the modes can be determined from the beam orbit that produces minimum power in the dipole HOM modes. The phase and amplitude of the dipole modes can be used to obtain high resolution beam position information, and the phase of the monopole modes to measure the beam phase relative to the accelerator rf. For most superconducting accelerators, the existing higher order mode couplers provide the necessary signals, and the downmix and digitizing electronics are straightforward, similar to those for a conventional beam position monitor.
Date: February 12, 2007
Creator: Molloy, S.; Frisch, J.; McCormick, D.; May, J.; Ross, M.; Smith, T. et al.
Partner: UNT Libraries Government Documents Department

Using Higher Order Modes in Superconducting Accelerating Cavities for Beam Monitoring

Description: Dipole modes have been shown to be successful diagnostics for the beam position in superconducting accelerating cavities at the Free Electron Laser in Hamburg (FLASH) facility at DESY. By help of downmixing electronics the signals from the two higher order mode (HOM) couplers mounted on each cavity are monitored. The calibration, based on singular value decomposition, is more complicated than in standard position monitors. Position like signals based on this calibration are currently being in the process of being included in the control system. A second setup based on digitizing the spectrum from the HOM couplers has been used for monitoring monopole modes. The beam phase with respect to the RF has been thus monitored. The position calibration measurements and phase monitoring made at the FLASH are presented.
Date: March 7, 2008
Creator: Molloy, S.; Baboi, N.; Eddy, N.; Frisch, J.; Hendrickson, L.; Hensler, O. et al.
Partner: UNT Libraries Government Documents Department

Beam Position Monitoring with Cavity Higher Order Modes in the Superconducting Linac FLASH

Description: FLASH (Free Electron Laser in Hamburg) is a user facility for a high intensity VUV-light source [1]. The radiation wavelength is tunable in the range from about 40 to 13 nm by changing the electron beam energy from 450 to 700 MeV. The accelerator is also a test facility for the European XFEL (X-ray Free Electron Laser) to be built in Hamburg [2] and the project study ILC (International Linear Collider) [3]. The superconducting TESLA technology is tested at this facility, together with other accelerator components.
Date: March 20, 2007
Creator: Baboi, N.; Molloy, S.; Eddy, N.; Frisch, J.; Hendrickson, L.; Hensler, O. et al.
Partner: UNT Libraries Government Documents Department