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Evaluation of Heat Dissipation in the BPM Buttons

Description: Growth of circulating current in the storage rings drastically increases heating of the beam position monitor (BPM) buttons due to the induced trapped modes is drastically increasing. Excessive heating can lead to the errors in the measuring of beam position or even catastrophic failures of the pick-up assembly. In this paper we present calculations of heat generated in the button for different geometries and materials. The obtained results are used for the optimization of the NSLS-II BPM buttons design.
Date: May 4, 2009
Creator: Pinayev,I. & Blednyhk, A.
Partner: UNT Libraries Government Documents Department

A General Analysis of Thin Wire Pickups for High Frequency Beam Position Monitors

Description: In many particle accelerators, a large number of high frequency beam position monitors (BPMs) are required to track and correct the orbit of the beam. Therefore, simple, sensitive, low cost pickup designs for such BPMs are of widespread interest. In this paper, a general analysis of arbitrarily terminated thin wire stripline or
Date: October 1, 1990
Creator: Barry, Walter
Partner: UNT Libraries Government Documents Department

Optimisation of NSLS-II Blade X-ray Beam Position Monitors: from Photoemission type to Diamond Detector

Description: Optimisation of blade type x-ray beam position monitors (XBPM) was performed for NSLS-II undulator IVU20. Blade material, con and #64257;guration and operation principle was analysed in order to improve XBPM performance. Optimisation is based on calculation of the XBPM signal spatial distribution. Along with standard photoemission type XBPM a Diamond Detector Blades (DDB) were analysed as blades for XBPMs. DDB XBPMs can help to overcome drawbacks of the photoemission blade XBPMs.
Date: July 10, 2012
Creator: P., ILINSKI
Partner: UNT Libraries Government Documents Department

Comparison of RF BPM Receivers for NSLS-II Project

Description: The NSLS-II Light Source being built at Brookhaven National Laboratory requires submicron stability of the electron orbit in the storage ring in order to utilize fully very small emittances and electron beam sizes. This sets high stability requirements for beam position monitors and a program has been initiated for the purpose of characterizing RF beam position monitor (BPM) receivers in use at other light sources. Present state-of-the-art performance will be contrasted with more recently available technologies.
Date: May 4, 2009
Creator: Pinayev,I. & Singh, O.
Partner: UNT Libraries Government Documents Department

Measurements of Beam Momentum at the Stacking Energy of the Accumulator

Description: The momentum and orbit length of beam on the central and extraction orbits of the Antiproton Source Accumulator are calculated from measurements of revolution frequency and transverse beam position. This report gives the results of measurements made at the stacking energy before and after the 1998-99 Accumulator lattice upgrade. Before the lattice upgrade, the Accumulator central orbit length and momentum are measured to be: L{sub c} = 474.0433 {+-} 0.0025 m, p{sub c} = 8819.5 {+-} 4.1 MeV/c. After the lattice upgrade the central orbit length and momentum are measured to be: L{sub c} = 474.0532 {+-} 0.0016 m, p{sub c} = 8803.4 {+-} 2.7 MeV/c. The extraction orbit length and momentum prior to the lattice upgrade are measured to be: L{sub e} = 474.1916 {+-} 0.0054 m, p{sub e} = 8900.8 {+-} 9.2 MeV/c. After the lattice upgrade the extraction orbit length and momentum are measured to be: L{sub e} = 474.1599 {+-} 0.0036 m, p{sub e} = 8886.3 {+-} 6.1 MeV/c.
Date: November 29, 2000
Creator: Werkema, Steve
Partner: UNT Libraries Government Documents Department

Phase and synchronous detector theory as applied to beam position and intensity measurements

Description: A popular signal processing technique for beam position measurements uses the principle of amplitude-to-phase (AM/PM) conversion and phase detection. This technique processes position-sensitive beam-image-current probe-signals into output signals that are proportional to the beam`s position. These same probe signals may be summed and processed in a different fashion to provide output signals that are proportional to the peak beam current which is typically referred to as beam intensity. This paper derives the transfer functions for the AM/PM beam position and peak beam current processors.
Date: May 1, 1995
Creator: Gilpatrick, J.D.
Partner: UNT Libraries Government Documents Department

Observation of the spread of the readings in the Linac toroids and BPMs

Description: The readback accuracy on the high-energy toroids is about 0.26 mA. This does not consider, completely, the relative offsets among the toroids, just the accuracy of one reading on one toroid. Similarly, if you remove the way in which the beam moves in the beam pipe and ignore the relative offsets of the BPMs themselves, then the absolute accuracy of the reading on a BPM is 35 microns.
Date: November 9, 2001
Creator: McCrory, Elliott S
Partner: UNT Libraries Government Documents Department

Measured longitudinal beam impedance of a Tevatron separator

Description: Twenty two separators are currently installed in the Tevatron. The longitudinal impedance of one of these devices was recently measured with a stretched wire. The stretched wire technique can only measure impedance below the cutoff frequency (500MHz). The geometry of a separator is similar to an un-terminated stripline beam position detector. The separator plates occupy a 13.5'' ID vacuum tank, are 101'' long, 7.8'' wide, and have a 2'' gap between them. The differential characteristic impedance between the plates is estimated to be 81 {Gamma} and the common mode impedance plate to ground is about 42 {Gamma}.
Date: December 9, 2002
Creator: Crisp, James L & Fellenz, Brian J
Partner: UNT Libraries Government Documents Department

RF systems for the betatron-node scheme experiment at LBNL

Description: Two-beam accelerators based upon relativistic klystrons (RK's) have been proposed as power sources for future generation electron-positron linear colliders. These drivers are known to suffer from several transverse beam-breakup (BBU) instabilities. A program to study a particular technique (the 'betatron node scheme') of ameliorating the high frequency BBU is under way at LBL. Central to this study are the pillbox RF cavities and RF beam position monitors (BPM's) employed. This paper discusses the design, fabrication, and testing of the RF components. Details of the signal processing and analysis will be presented.
Date: June 22, 2001
Creator: Lidia, Steven M.; De Santis, Stefano & Houck, Timothy
Partner: UNT Libraries Government Documents Department

Optical sensors for accelerator diagnostics. Final report for the period September 15, 1998 - September 14, 2001

Description: DARHT utilizes a long pulse electron beam having a duration in excess of 2 microseconds. An electro-optic voltage sensor technology has been developed and commissioned to address this unique diagnostic environment. Over 200 sensors have demonstrated 0.25% accuracy. Deployment is expected in 2002.
Date: April 8, 2002
Creator: Yakymyshyn, Christopher P.
Partner: UNT Libraries Government Documents Department

Evaluation and Correction of the Non-linear Distortion of CEBAF Beam Position Monitors

Description: The beam position monitors at CEBAF have four antenna style pickups that are used to measure the location of the beam. There is a strong nonlinear response when the beam is far from the electrical center of the device. In order to conduct beam experiments at large orbit excitation we need to correct for this nonlinearity. The correction algorithm is presented and compared to measurements from our stretched wire BPM test stand.
Date: September 1, 2011
Creator: M. Spata, T.L. Allison, K.E. Cole, J. Musson, J. Yan
Partner: UNT Libraries Government Documents Department

Quadrupole Beam-Based Alignment in the RHIC Interaction Regions

Description: Continued beam-based alignment (BBA) efforts have provided significant benefit to both heavy ion and polarized proton operations at RHIC. Recent studies demonstrated previously unknown systematic beam position monitor (BPM) offset errors and produced accurate measurements of individual BPM offsets in the experiment interaction regions. Here we describe the algorithm used to collect and analyze data during the 2010 and early 2011 RHIC runs and the results of these measurements.
Date: March 1, 2011
Creator: Satogata, T.
Partner: UNT Libraries Government Documents Department

Calibrating transport lines using LOCO techniques

Description: With the 12GeV upgrade underway at CEBAF, there is a need to re-characterize the beamlines after the modifications made to it to accommodate running at higher energies. We present a linear perturbation approach to calibrating the optics model of transport lines. This method is adapted from the LOCO method in use for storage rings. We consider the effect of quadrupole errors, dipole construction errors as well as beam position monitors and correctors calibrations. The ideal model is expanded to first order in Taylor series of the quadrupole errors. A set of difference orbits obtained by exciting the correctors along the beamline is taken, yielding the measured response matrix. An iterative procedure is invoked and the quadrupole errors as well as beam position monitors and corrector calibration factors are obtained. Here we present details of the method and results of first measurements at CEBAF in early 2011.
Date: September 1, 2011
Creator: Roblin, Yves
Partner: UNT Libraries Government Documents Department

Direct focusing error correction with ring-wide TBT beam position data

Description: Turn-By-Turn (TBT) betatron oscillation data is a very powerful tool in studying machine optics. Hundreds and thousands of turns of free oscillations are taken in just few tens of milliseconds. With beam covering all positions and angles at every location TBT data can be used to diagnose focusing errors almost instantly. This paper describes a new approach that observes focusing error collectively over all available TBT data to find the optimized quadrupole strength, one location at a time. Example will be shown and other issues will be discussed. The procedure presented clearly has helped to reduce overall deviations significantly, with relative ease. Sextupoles, being a permanent feature of the ring, will need to be incorporated into the model. While cumulative effect from all sextupoles around the ring may be negligible on turn-to-turn basis it is not so in this transfer line analysis. It should be noted that this procedure is not limited to looking for quadrupole errors. By modifying the target of minimization it could in principle be used to look for skew quadrupole errors and sextupole errors as well.
Date: March 1, 2011
Creator: Yang, M.J.
Partner: UNT Libraries Government Documents Department

Emittance measurements using Vernier Scans during Run 09 (pp at 250 GeV)

Description: Emittance measurements using the vernier scan technique give reliable results for 250 GeV protons even though the transverse beam profiles have non-Gaussian tails. Those non-Gaussian tails were observed for the first time this run at the 250 GeV beam energy. The vernier scan measurements are in excellent agreement with the emittances derived from collision rates and show practically no fill to fill scatter if compared to the latter. The results are consistent with a {beta}* of 0.7 m and round beams. The IPM measurements show a discrepancy of up to 80% compared with the vernier scan data and a fill to fill scatter of up to 30%. If an uncertainty in the beta-function at the location of the IPM is the root cause, this uncertainty seems to be quite large. In any case, such an uncertainty could not explain the fill to fill variations of up to 30% which indicate yet another underlying reason that could explain fill to fill variations (candidates could be beam intensity issues with the IPM, beam position at the IPM, varying background etc.).
Date: November 1, 2010
Creator: Drees, A.
Partner: UNT Libraries Government Documents Department


Description: To further improve the luminosity in polarized proton operation of the Relativistic Heavy Ion Collider, correction of the horizontal two-third resonance at store is desirable. The long-lasting coherent beam oscillations, produced by the AC dipole, are used to measure 3Q,'s resonance driving term h{sub 30000} through the analysis of turn-by-turn beam position data with the algorithm outlined by J. Bengtsson. The resonance driving term h30000 can be compensated with the 12 arc chromatic sextupole families. In this article, we will review the technique of h{sub 30000} resonance driving term's measurement and correction with AC dipole excitation in the RHIC, followed by the preliminary beam experiment results from the RHIC 2006 polarized proton run.
Date: June 25, 2007
Partner: UNT Libraries Government Documents Department

R_transport_matrices of the Fast Extraction Beam (FEB) of the AGS, and Beam Parameters at the Starting point of the AtR Line

Description: As part of the task to improve and further automate the 'AtR BPM Application' we provide the theoretically calculated R-transport-matrices for the following beam line sections, which are shown schematically in Figure 1: (a) the Fast Extraction Beam section (FEB) of the AGS synchrotron. The FEB section starts at the middle of the GlO-kicker and ends at the middle of the H1 0{_}septum. (b) the Drift Extraction Channel (DEC) section of the AGS synchrotron. The DEC section starts at the middle of the H10{_}septum, continues along the fringe field region of the H11,H12, and H13 AGS main magnets, and ends at the starting point of the AtR line. The knowledge of these R-transport-matrices are needed in order to calculate the beam parameters at the beginning of the AtR line, which in turn, are required to calculate the magnet settings of the U{_}line, that match the U{_}line into the W{_}line. Also by incorporating these R{_}matrices into the model of the AtR line, the G10 kicker and the H10 septum are included in the AtR model therefore one can investigate any 'jitter' of either the GlO{_}kicker or HlO{_}septum by looking at the trajectory of the beam in the AtR line.
Date: January 1, 2008
Creator: Tsoupas,N.; MacKay, W.W.; Satogata, T.; Glenn, W.; Ahrens, L.; Brown, K. et al.
Partner: UNT Libraries Government Documents Department

On the Optimal Number of Eigenvectors for Orbit Correction

Description: The singular value decomposition method is widely used for orbit correction in the storage rings. It is a powerful tool for inverting of the usually rectangular response matrices, which usually have rectangular form. Another advantage is flexibility to choose number of eigenvectors for calculation of required strengths of orbit correctors. In particular, by reduction in number of eigenvectors one can average over ensemble the noise in the beam position monitors. A theoretical approach as well as experimental results on the NSLS VUV ring is presented.
Date: June 23, 2008
Creator: Pinayev,I.
Partner: UNT Libraries Government Documents Department

Weighted SVD algorithm for close-orbit correction and 10 Hz feedback in RHIC

Description: Measurements of the beam position along an accelerator are typically treated equally using standard SVD-based orbit correction algorithms so distributing the residual errors, modulo the local beta function, equally at the measurement locations. However, sometimes a more stable orbit at select locations is desirable. In this paper, we introduce an algorithm for weighting the beam position measurements to achieve a more stable local orbit. The results of its application to close-orbit correction and 10 Hz orbit feedback are presented.
Date: May 20, 2012
Creator: C., Liu; Hulsart, R.; Marusic, A.; Michnoff, R.; Minty, M. & Ptitsyn, V.
Partner: UNT Libraries Government Documents Department

Development of Electronics for the ATF2 Interaction Point Region Beam Position Monitor

Description: Nanometer resolution beam position monitors have been developed to measure and control beam position stability at the interaction point region of ATF2. The position of the beam has to be measured to within a few nanometers at the interaction point. In order to achieve this performance, electronics for the low-Q IP-BPM was developed. Every component of the electronics have been simulated and checked on the bench and using the ATF2 beam. We will explain each component and define their working range. Then, we will show the performance of the electronics measured with beam signal. ATF2 is a final focus test beam line for ILC in the framework of the ATF international collaboration. The new beam line was constructed to extend the extraction line at ATF, KEK, Japan. The first goal of ATF2 is the acheiving of a 37 nm vertical beam size at focal point (IP). The second goal is to stabilize the beam at the focal point at a few nanometer level for a long period in order to ensure the high luminosity. To achieve these goals a high resolution IP-BPM is essential. In addition for feedback applications a low-Q system is desirable.
Date: August 14, 2012
Creator: Kim, Youngim; U., /Kyungpook Natl.; Heo, Ae-young; U., /Kyungpook Natl.; Kim, Eun-San; U., /Kyungpook Natl. et al.
Partner: UNT Libraries Government Documents Department