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in creator/contributor: "Ahrens, L."

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Method for determining the position, angle and other injection parameters of a short pulsed beam in the Brookhaven AGS

As part of the effort to improve the monitoring of the injection process at the Brookhaven Alternating Gradient Synchrotron (AGS), we have developed a beam diagnostics package which processes the signals from the plates of a pick-up electrode (PUE) located near the injection region of the AGS and provides measurements of the position and angle (with respect to the equilibrium orbit) of the injected beam at the stripping foil where the incident H/sup -/ beam is converted into protons. In additio… more

Date: January 1, 1985

Creator: Gardner, C. & Ahrens, L.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Polarized proton acceleration at the BNL AGS, 1988

The present status of the polarized proton acceleration at the Brookhaven AGS is described. Some details regarding the tune-up and performance during the December 1987-January 1988 physics run are given. 2 refs., 4 figs.

Date: January 1, 1988

Creator: Ahrens, L.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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RHIC polarized proton performance in run-8.

During Run-8, the Relativistic Heavy Ion Collider (RHIC) provided collisions of spin-polarized proton beams at two interaction regions. Helical spin rotators at these two interaction regions were used to control the spin orientation of both beams at the collision points. Physics data were taken with different orientations of the beam polarization. We present recent developments and improvements as well as the luminosity and polarization performance achieved during Run-8.

Date: June 23, 2008

Creator: Montag, C.; Abreu, N.; Ahrens, L.; Bai, M.; Barton, D. & al., et

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Polarization Issues in Run 2008

The RHIC proton beam polarization has a strong dependence on intensity in Run 2008, whereas the dependence is almost absent in Run 2006. Meanwhile, the RHIC beam transverse emittance also has a dependence on intensity in Run 2008, but little in Run 2006. Using the emittance measurement at the AGS IPM and the BtA multiwires, the source of this difference between 2006 and 2008 runs is traced to the Booster. It is found that at least the degree of the vertical scraping in the Booster is different … more

Date: July 1, 2008

Creator: Zhang, S. Y.; Ahrens, L.; Huang, H. & Zeno, K.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Beam Transport of 4 GeV Protons from AGS to the Proton Interrogation Target of the Neutrino Line (Z_line) and Effect of the Air on the Transported Beam

As part of the preparation for the Proton Interrogation Experiment, we have calculated the beam optics for the transport of 4 GeV protons, from the AGS extraction point, to the 'Cross-Section Target Wheel 1' and to the 'Proton Interrogation Target'. In this technical note we present three possible beam-transports each corresponding to a particular Fast Extracted Beam W B setup of the AGS. In addition we present results on the effect of the atmospheric air, (which fills the drift space of the la… more

Date: October 1, 2008

Creator: Tsoupas, N.; Ahrens, L.; Pile, P.; Thieberger, P. & Murray, M. M.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Effects of Booster Scraping in Polarized Proton Runs 2006 and 2008

Effects of the Booster vertical scraping on the RHIC beam polarization, the RHIC beam emittance, and on the Booster to AGS transfer efficiency and AGS transmission as well, are further studied. In [1], the strong dependence of the RHIC beam polarization and emittance on bunch intensity in proton run 2008 (pp08) is compared with the proton run 2006 (pp06), where the dependence is much weaker. The setting in the AGS Booster, mainly the vertical scraping, is suspected to having played a role in th… more

Date: January 2, 2009

Creator: Zhang, S. Y.; Ahrens, L.; Huang, H. & Zeno, K.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Booster-to-AGS Multiwires and an Evolution of the Application Profile Display

Follow up on BtA multiwire beam measurements taken during the 2008 polarized proton run has led to a number of better understandings (for the author) associated with the beam instrumentation involved. This history will be reviewed--some 'beam-based' results noted--and the present state of the application for these monitors described. The BtA multiwire system seems to be fundamentally an excellent diagnostic for allowing us to get the BtA line well under control in a defendable way. When beam is… more

Date: July 1, 2008

Creator: Ahrens, L.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Injection and Acceleration of Au31+ in the BNL AGS.

Injection and acceleration of ions in a lower charge state reduces space charge effects, and, if further elcctron stripping is needed, may allow elimination of a stripping stage and the associated beam losses. The former is of interest to the accelerators in the GSI FAIR complex, the latter for BNL RHIC collider operation at energies lower than the current injection energy. Lower charge state ions, however, have a higher likelihood of electron stripping which can lead to dynamic pressures rises… more

Date: June 23, 2008

Creator: Fischer, W.; Ahrens, L.; Brown, K.; Gardner, C.; Glenn, W.; Huang, H. et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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

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 t… more

Date: January 1, 2008

Creator: Tsoupas, N.; MacKay, W. W.; Satogata, T.; Glenn, W.; Ahrens, L.; Brown, K. et al.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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AGS polarized proton operation in run 8.

Dual partial snake scheme has been used for the Brookhaven AGS (Alternating Gradient Synchrotron) polarized proton operation for several years. It has provided polarized proton beams with 1.5 x 10{sup 11} intensity and 65% polarization for RHIC spin program. There is still residual polarization loss. Several schemes such as putting horizontal tune into the spin tune gap, and injection-on-the-fly were tested in the AGS to mitigate the loss. This paper presents the experiment results and analysis. more

Date: June 23, 2008

Creator: Huang, H.; Ahrens, L.; Bai, M.; Brown, K. A.; Gardner, C.; Glenn, J. W. et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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RHIC Performance with polarized protons in run-6

In this study, an array of vibration measurements at the undisturbed NSLS II site has been performed in order to establish the 'green-field' vibration environment and its spectral characteristics. The interaction of the green-field vibration environment with the NSLS II accelerator structure and the quantification of the storage ring vibration, both in terms of amplitude and spectral content have been assessed through a state-of-the-art wave propagation and scattering analysis. This paper focus… more

Date: October 2, 2006

Creator: Ptitsyn, V.; Ahrens, L.; Bai, M.; Beebe-Wang, J.; Blaskiewicz, M.; Bravar, S. et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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A fast chopper for programmed population of the longitudinal phase space of the AGS

A fast beam chopper has been built that can produce an arbitrary pulse program of the 200 MeV H/sup /minus// beam for synchronous injection into moving rf buckets in the AGS. The chopper will eliminate rf capture losses and can be used to tailor the initial distribution in longitudinal phase space by varying the pulse parameters, width and phase, on a bunch-by-bunch time scale, during multi-turn injection. The chopper also serves as a studies tool since it can provide controllable beam intensit… more

Date: January 1, 1989

Creator: Brennan, J. M.; Ahrens, L.; Alessi, J.; Brodowski, J.; Kats, J. & van Asselt, W.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Workshop on the AGS fixed-target research program

The summarized results of a two day workshop to determine experiment programs for the Brookhaven AGS during the construction period of the ISABELLE storage rings and after are presented. Topics covered include: experiments with low-energy beams; experiments with higher energy beams; neutrino physics; and polarized protons. (GHT)

Date: January 1, 1978

Creator: Ahrens, L.; Schewe, P.; Wanderer, P. & Weisberg, H.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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First results of proton injection commissioning of the AGS Booster synchrotron

Beam performance for the injection phase of proton beam commissioning of the AGS Booster synchrotron will be presented. The beam from the 200 MeV Linac is transported through a new beam line into the Booster. This Linac-to Booster (LTB) beam line includes a 126{degree} bend and brings the injected beam onto the Booster injection orbit through the backleg of a main ring dipole magnet. Transfer of beam from the Linac to the Booster, spiralling beam and closing the orbit in the Booster ring are di… more

Date: January 1, 1991

Creator: Reece, R. K.; Ahrens, L.; Alessi, J.; Bleser, E.; Brennan, J. M.; Luccio, A. et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Operational experience and techniques for controlled longitudinal phase space dilution in the AGS using a high harmonic cavity

A fixed frequency 93 MHz harmonic cavity has been installed in the AGS ring. The primary purpose of this harmonic cavity is to increase (dilute) the longitudinal phase space area occupied by the beam by as much as a factor of four (to 4.0 eV-s) in a controlled, rapid manner while maintaining a smooth local density. This then will permit essentially lossless passage through transition energy (8.0 GeV) at intensities higher than previously achieved. Although the system controls permit as many as … more

Date: January 1, 1989

Creator: Reece, R. K.; Ahrens, L.; Abola, A.; Brennan, J. M.; Cameron, P.; Ciardullo, D. et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Increased intensity performance of the Brookhaven AGS

With the advent of H/sup -/ injection into the Brookhaven AGS, circulating beams of up to 3 x 10/sup 13/ protons at 200 MeV have been obtained. Rf capture of 2.2 x 10/sup 13/ and acceleration of 1.73 x 10/sup 13/ up to the transition energy (approx. = 8 GeV) and 1.64 x 10/sup 13/ to full energy (approx. = 29 GeV) has been achieved. This represents a 50% increase over the best performance obtained with H/sup +/ injection. The increase in circulation beam current is obtained without filling the h… more

Date: May 1, 1985

Creator: Raka, E.; Ahrens, L.; Frey, W.; Gill, E.; Glenn, J.W.; Sanders, R. et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Construction and early commissioning results of the AGS Booster

The AGS Booster synchrotron has been designed to accelerate protons from 200 MeV to 1.5 GeV and heavy ions from several MeV per nucleon to several hundred MeV per nucleon for all the nuclei up to gold. The design requirements and measurements results of major accelerator components and systems are presented. The early commissioning results of the injection is also presented. 12 refs., 9 figs., 2 tabs.

Date: January 1, 1991

Creator: Weng, W. T.; Ahrens, L.; Damm, R. & McNerney, A. J.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Low-level rf system for the AGS Light Ion Program

The new low level rf system for the light ion acceleration program features direct digital control of a phase continuous rf synthesizer clocked by finite changes in the B field. The system, its operation and testing are described. The system covers the complete rf frequency range and switches over from single cavity acceleration to multiple cavity acceleration with no beam loss. It also switches from the programmed drive to the normal bootstrap system.

Date: January 1, 1987

Creator: Kovarik, V.; Ahrens, L.; Barton, D. S.; Frankel, R.; Otis, A.; Pope, D. et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Bunch-to-bucket injection of linac beam into the Brookhaven AGS

A new fast beam chopper has been used to study injection and capture in the AGS. The chopper is a fast beam switch with 10 ns rise and fall times that can be programmed on a bunch-by-bunch basis and is synchronized to the net accelerating voltage of the synchrotron, thus allowing bunch-to-bucket injection of the 200 MeV H{sup {minus}} linac beam. The studies so far have concentrated on simple injection scenarios, at reduced intensity, where longitudinal effects are well separated from transvers… more

Date: January 1, 1990

Creator: Brennan, J. M.; Ahrens, L. & Kats, J.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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A [gamma][sub t]-jump scheme for the Brookhaven AGS

AGS beam losses at transition are now tolerable ([lt]5%), but as the present improvement plans are implemented and the intensity is increased, new mechanisms will become important and the losses will increase. This Note describes studies directed towards minimizing these losses. Werner Hardt has studied these losses at the CERN PS. In particular, he found that by sharply reducing the time spent going through transition he could reduce the losses. Hardt visited Brookhaven in early June, 1986, in… more

Date: April 23, 1993

Creator: Ahrens, L.; Auerbach, E.; Hardt, W.; Raka, E.; Ratner, L. & Yamin, P.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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A {gamma}{sub t}-jump scheme for the Brookhaven AGS

AGS beam losses at transition are now tolerable ({lt}5%), but as the present improvement plans are implemented and the intensity is increased, new mechanisms will become important and the losses will increase. This Note describes studies directed towards minimizing these losses. Werner Hardt has studied these losses at the CERN PS. In particular, he found that by sharply reducing the time spent going through transition he could reduce the losses. Hardt visited Brookhaven in early June, 1986, in… more

Date: April 23, 1993

Creator: Ahrens, L.; Auerbach, E.; Hardt, W.; Raka, E.; Ratner, L. & Yamin, P.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Observation and correction of resonance stopbands in the AGS Booster

At the design intensity of 1.5 {times} 10{sup 13} ppp, the space charge tune shift in the AGS Booster at injection has been estimated to be about 0.35. Therefore, the beam is spread over may lower order resonance lines and the stopbands have to be corrected to minimize the amplitude growth by proper compensation of the driving harmonics resulting from random errors. The observation and correction of second and third order resonance stopbands in the AGS Booster, and the establishment of a favora… more

Date: June 1, 1993

Creator: Gardner, C.; Shoji, Y.; Ahrens, L.; Glenn, J. W.; Lee, Y. Y.; Roser, T. et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Experimental study of slow-rate transition crossing in AGS

The nonlinear momentum-compaction factor {alpha}{sub 1} has been obtained in the AGS by measuring transition energies at different radial orbits using a low-intensity slow-ramped Au{sup 77+} beam. The beam loss during the transition crossing is found to increase with increasing rf voltage, and to decrease with increasing ramping rate, which indicates that the effect of chromatic nonlinearity (Johnson effect) dominates the transition crossing. The experimental measurement of beam loss agrees ver… more

Date: August 1, 1994

Creator: Wei, J.; Warner, A. & Ahrens, L.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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The operational status of the Booster injector for the AGS accelerator complex at BNL

The Booster synchrotron at Brookhaven National Laboratory has been incorporated into the accelerator chain at the Alternating Gradient Synchrotron (AGS) complex. After a successful first commissioning effort in the spring of 1991, the Booster has been part of this year`s silicon, gold and proton physics runs. After a brief review of the Booster design goals, and of the early commissioning, this paper will summarize this year`s activities.

Date: September 1, 1992

Creator: Ahrens, L.; Bleser, E.; Brennan, J. M.; Gardner, C.; Gill, E.; Glenn, J. W. et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department