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AGS polarized beam facility

Description: On February 23, 1984, 2 ..mu..A of polarized H/sup -/ was accelerated through the linac to 200 MeV with a polarization of 65%. 1 ..mu..A was injected into the AGS and acceleration attempts began. Several short tests were made until June 1984 when full time effort began. By June 26, the AGS polarized beam reached 13.8 GeV/c to eclipse the previous world's high energy of 12.75 GeV/c set at the Argonne ZGS some six years earlier. The polarized beam energy was raised to 16.5 GeV/c at which energy the decision was made to commence high energy physics running. By this time the accelerated beam intensity exceeded 10/sup 10/ protons per pulse with about 40% polarization. The beam was extracted and two experiments began taking data.
Date: January 1, 1985
Creator: Ratner, L.G.
Partner: UNT Libraries Government Documents Department

Correcting the AGS depolarizing resonances

Description: For the 1986 AGS run, the technique of correcting an imperfection resonance using a beat harmonic instead of the direct harmonic was applied and found to be useful in achieving a 22 GeV/c polarized beam. Both conventional and modified techniques are explained. (LEW)
Date: January 1, 1986
Creator: Ratner, L.G.
Partner: UNT Libraries Government Documents Department

Acceleration of polarized protons at the AGS

Description: Spin physics in the past has provided an acid test of many models and theories and over the last decade has revealed new and unexpected phenomena to confront present day theories. This work received great impetus from the experiments at the ZGS, where for the first time multi-GeV polarized beams became available. This, in conjunction with polarized targets, allowed the complete specification of the initial quantum states in high energy proton-proton interactions and led to many startling new results. Although spin effects were important at the previously measured lower energies, practically all theorists felt that spin effects would become negligible at higher energies. Instead, the ZGS results showed in many cases even larger effects than those observed at lower energies. By the time the ZGS was shut down in 1979, high energy polarized proton projects were planned for KEK in Japan, SATURNE in France, and the AGS at Brookhaven. At present, serious thought is being given to high energy polarized proton beams at Fermilab, CERN, and indeed in planning for the Superconducting Super Collider. Today, I would like to describe the facility at Brookhaven and give you the present status of the project. We have been in the commissioning phase for the last three months on a part-time basis. To date we have injected 7 ..mu..A of polarized protons with 70% polarization. We have accelerated a peak of 6.4 x 10/sup 9/ polarized protons to 10.3 GeV/c and have made a first pass at correcting about a dozen imperfection resonances and two intrinsic resonances. We believe that this first tune gave us about an 80% polarization survival from injection to 10.3 GeV/c. The goal was to achieve 26 GeV/c polarized protons with about an 80% polarization survival and an intensity greater than 10/sup 10/ per pulse.
Date: May 30, 1984
Creator: Ratner, L .G.
Partner: UNT Libraries Government Documents Department

Recent experience in accelerating polarized beam at the AGS

Description: The most recent operation of the AGS for polarized protons occurred in December, 1987 and January, 1988. The primary purpose during this period was to tune up the accelerator as soon as possible and to provide a usable polarized beam for high energy physics. We succeeded in providing 1--2 /times/ 10/sup 10/ polarized protons per pulse at 18.5 GeV/c with an average polarization of 43 +- 3% and a peak of 52%. The conditions for this run differed in some respects from the previous run done in 1986. Due to problems with the main ring power supply, we were forced to use a back-up MG set which was only capable of 60% of the normal field rate of rise. This, of course enhanced the effect of the depolarizing resonances. A second difference was the fact that a complete horizontal and vertical realignment of the ring magnets was done during the 1987 summer shutdown. In addition, the fast pulsed quadrupole positions were readjusted with respect to the equilibrium orbit. It had been suspected that misalignment of these quads was responsible for large transverse emittance growth in both planes. We will look at the effects of these differences, but the bottom line is that the ''standard correction techniques'' worked as expected. 2 refs., 6 figs.
Date: January 1, 1988
Creator: Ratner, L.G.
Partner: UNT Libraries Government Documents Department

Recent developments at BNL

Description: Topics of interest to the Saturne program, including the status of the polarized beam project, and the accumulator/booster ring, are discussed. The status of the colliding beam accelerator (CBA) is covered. (GHT)
Date: January 1, 1983
Creator: Ratner, L.G.
Partner: UNT Libraries Government Documents Department

Polarization preservation in the AGS

Description: The successful operation of a high energy polarized beam at the Argonne Zero Gradient Synchrotron (ZGS) with the concommitant development of depolarizing resonance correction techniques has led to the present project of commissioning such a beam at the Brookhaven Alternating Gradient Synchrotron (AGS). A description of the project was presented at the 1981 National Accelerator Conference. I would like to now present a more detailed description of how we plan to preserve the polarization during acceleration, and to present our game plan for tuning through some 50 resonances and reaching our goal of a 26 GeV polarized proton beam with greater than 60% polarization.
Date: January 1, 1983
Creator: Ratner, L.G.
Partner: UNT Libraries Government Documents Department

A partial snake for the AGS

Description: Based on snake experiments at the Indian University Cyclotron Facility and computer simulations at Brookhaven National Laboratory, as well as the conclusions of a BNL mini-workshop, we feel that a partial Siberian snake is a practical device for the AGS. It is anticipated that such a device could reduce the polarized beam tune-up time from 2--3 weeks to 2--3 days.
Date: January 1, 1990
Creator: Ratner, L.G.
Partner: UNT Libraries Government Documents Department

Siberian Snake solenoid for the AGS

Description: Recent experiments at the Indiana University Cyclotron Facility (IUCF) have demonstrated that Siberian Snakes'' can be used to preserve the polarization of an accelerated polarized beam in a circular accelerator. Retrofitting full snakes into accelerators such as the Alternating Gradient Synchrotron (AGS) at Brookhaven is almost impossible due to space limitations, but a partial snake that can correct depolarization due to imperfection resonances with 1/20 to 1/30 of a full strength snake seems to present a viable option. We describe such a device for the AGS and give the design criteria in terms of simplicity of accelerator operation and level of achievable polarization. 2 refs., 5 figs., 1 tab.
Date: January 1, 1991
Creator: Ratner, L. G.
Partner: UNT Libraries Government Documents Department

Upgrading the AGS polarized beam facility

Description: Although present techniques for crossing depolarizing resonances in circular accelerators work, they are very time-consuming to implement and were only able to provide about a 40% polarized beam at 22 GeV in the Alternating Gradient Synchrotron (AGS). We propose to install a partial Siberian Snake'' solenoid in the AGS to eliminate the need to correct imperfection resonances and to make other modifications in our intrinsic resonance correctors. This will allow us to reach an energy of 25 GeV with 70% polarization and will enable the AGS to be an efficient injector of polarized protons into the Relativistic Heavy Ion Collider (RHIC), as well as being able to carry on a fixed-target program with minimum set-up time. 3 refs., 5 figs., 1 tab.
Date: January 1, 1991
Creator: Ratner, L.G.
Partner: UNT Libraries Government Documents Department

Summary of the working group on the construction and demonstration of a Siberian Snake

Description: It was recognized as long ago as the 1977 Ann Arbor Meeting on Higher Energy Polarized Proton Beams that a ''Siberian Snake'' should be built and tested in an operating accelerator. A program to accomplish this at Argonne National Laboratory (ANL) was part of a proposal to DOE to construct a small R and D accelerator at ANL. This was never implemented and between then and now many theory papers have been written but no Proof of Principle Experiment (POPE) has been done. The present Ann Arbor workshop again strongly recommends that a POPE be implemented as soon as possible since it has important consequences for all of the new higher energy machines. This ''Demo Snake'' working group zeroed in on the Alternating Gradient Synchrotron (AGS) as the place where such a project could now be most effectively done. The AGS has a polarized beam and knowledgeable theoretical and experimental accelerator physicists who have been working with polarized beams in accelerators for the last few years. Referring to the information contained in the introductory remarks to the working group on the characteristics of snakes, we detail the necessary design for the AGS.
Date: January 1, 1985
Creator: Ratner, L.G. & Raylman, R.R.
Partner: UNT Libraries Government Documents Department

Tune space manipulations in jumping depolarizing resonances

Description: In February 1986, the AGS polarized beam reached a momentum of 22 GeV/c with a 45% polarization and an intensity of 1 to 2 x 10/sup 10/ polarized protons per pulse at a repetition rate of 2.1 seconds. In order to achieve this, one had to overcome the effect of some 40 depolarizing resonances. In our first commissioning run in 1984, we had reached 16.5 GeV/c using, with suitable modifications, the conventional techniques first used at the Argonne ZGS. This worked well, but we found that the fast tune shifts required to cross the intrinsic depolarizing resonances were causing an increase in beam emittance which led to the need for stronger corrections later in the cycle and to diminished extraction efficiency. For the 1986 run, we were prepared to minimize this emittance growth by the application of slow quadrupole pulses to change the region in tune space in which we operated the first tune quads. In this paper we give a brief description of the conventional corrections, but our main emphasis is on the descriptions of tune space manipulations.
Date: January 1, 1987
Creator: Ratner, L.G. & Ahrens, L.A.
Partner: UNT Libraries Government Documents Department

Measurement of A and A/sub nn/ in p + p. -->. p + p at 6 GeV/c

Description: Previous measurements of the 6 GeV/c p - p elastic scattering rates have been extended with beam and target polarizations normal to the scattering plane. Improvements to the measuring technique include additional momentum resolution added to the recoil arm and increased solid angle resulting from two-element hodoscopes. Beam intensity was increased by a factor of 3 and additional shielding was installed. Along with the usual statistical uncertainty and errors in measurement of the target polarization, a term was added in quadrature due to a systematic difference between target and beam asymmetries (A/sub T/ and A/sub B/). (GHT)
Date: January 1, 1980
Creator: Crosbie, E.A.; Ratner, L.G. & Schultz, P.F.
Partner: UNT Libraries Government Documents Department

200-GeV proton-proton elastic scattering at high transverse momentum

Description: This is a proposal to study p-p elastic scattering at the highest possible P{sub {perpendicular}}{sup 2} at NAL, using a CH{sub 2} or H{sub 2} target placed directly in the extracted beam and a double arm spectrometer. We expect to be able to set an upper limit at the level d{sigma}/dt/d{sigma}/dt{sub t=0} {approx} 10{sup -14}. This would be sufficient to determine if there are exactly three regions in the p-p interaction with considerable precision.
Date: June 1, 1970
Creator: Ratner, L.G.; /Argonne; Krisch, A.D.; Roberts, J.B.; Terwilliger, K.M. & U., /Michigan
Partner: UNT Libraries Government Documents Department

Design and test results of a pulsed quadrupole magnet with a 2. mu. s rise time

Description: Major polarization losses will be encountered during acceleration of polarized protons in the Brookhaven AGS due to eight intrinsic depolarizing resonances. Pulsing a set of 12 vertical tune shift quadrupole magnets with a 2 ..mu..s rise time, 3 ms fall, and 60 ms repetition rate should reduce these losses. This requires a gradient of 1.87 T/M over the 8.89 x 12.7 cm vacuum chamber. A ferrite core quadrupole magnet has been designed, built, and magnetically measured. The pole tip has a hyperbolic shape and the coil consists of four parallel 0.318 cm by 0.453 cm turns per pole. This approximates a current sheet 0.318 cm thick and curves to lie along a flux line. Placed as close to the vacuum chamber as possible, it minimizes the inductance of the magnet and the voltage of the power supply. Proper spacing of the four turns assures a more uniform gradient over a large aperture. Two slabs of ferrite are bonded together and machined to form one pole of half length. These are bonded end-to-end, and a prewound coil on a fiberglass support is attached. Four such pole assemblies are then assembled around the vacuum chamber and electrically connected together. The design, construction, and measurements are presented.
Date: January 1, 1981
Creator: Bywater, J.A.; Lari, R.J.; Ratner, L.G.; Lee, Y.Y.; Fujisaki, M.; Krisch, A.D. et al.
Partner: UNT Libraries Government Documents Department

Commissioning the polarized beam in the AGS

Description: After the successful operation of a high energy polarized proton beam at the Argonne Laboratory Zero Gradient Synchrotron (ZGS) was terminated, plans were made to commission such a beam at the Brookhaven National Laboratory Alternating Gradient Synchrotron (AGS). On February 23, 1984, 2 ..mu..A of polarized H/sup -/ was accelerated through the Linac to 200 MeV with a polarization of about 65%. 1 ..mu..A was injected into the AGS and acceleration attempts began. Several relatively short runs were then made during the next three months. Dedicated commissioning began in early June, and on June 26 the AGS polarized beam reached 13.8 GeV/c to exceed the previous ZGS peak momentum of 12.75 GeV/c. Commissioning continued to the point where 10/sup 10/ polarized protons were accelerated to 16.5 GeV/c with 40% polarization. Then, two experiments had a short polarized proton run. We plan to continue commissioning efforts in the fall of this year to reach higher energy, higher intensity, and higher polarization levels. We present a brief description of the facility and of the methods used for preserving the polarization of the accelerating beam.
Date: January 1, 1985
Creator: Ratner, L.G.; Brown, H.; Chiang, I.H.; Courant, E.; Gardner, C.; Lazarus, D. et al.
Partner: UNT Libraries Government Documents Department

Possibility of acceleration of polarized protons in the Brookhaven AGS

Description: The unexpected importance of high energy spin effects and the success of the 12 GeV Argonne ZGS in jumping many intrinsic and imperfection depolarizing resonances suggests that polarized proton acceleration should be tried at higher energy. The 1977 Ann Arbor Workshop concluded that it might be possible to jump depolarizing resonances in strong focusing synchrotrons. During the past year we have evaluated the possibility of accelerating polarized protons in the Brookhaven AGS. We found that for about $2 million one could obtain a polarized ion source, fast resonance jumping magnets, and 3 polarimeters which should allow acceleration of 10/sup 11/ to 10/sup 12/ polarized protons to 23 GeV/c with about 70= polarization or to 26 GeV/c with about 50% polarization.
Date: January 1, 1979
Creator: Crabb, D.G.; Krisch, A.D.; Terwilliger, K.M.; Cork, B.; Courant, E.D.; Feltman, A. et al.
Partner: UNT Libraries Government Documents Department

Spin Effects in High-P(T)^2 p+p --> p+p at 800 to 900 GeV

Description: We propose to study the spin-orbit Analyzing Power, A, in p+p + p+p at large P{sub {perpendicular}}{sup 2}. We propose to run at Fermilab around Fall 1987 and scatter a high intensity unpolarized proton beam of 800 to 900 GeV from a Polarized Proton Target; we would measure the difference between the d{sigma}/dt when the target spin is up and when it is down. Our main goal is to see if the unexpected large values of A recently found at the 28 GeV AGS in proton-proton elastic scattering persist to Fermilab energies. The large A value of 24 {+-} 8% at P{sub {perpendicular}}{sup 2} = 6.5 (GeV/c){sup 2} was not only unexpected but also seems difficult to reconcile with the A = 0 prediction of conventional models of strong interactions, such as perturbative QCD. The validity of perturbative QCD is believed to improve with increasing energy and with increasing P{sub {perpendicular}}{sup 2}, and this proposed Fermilab experiment would increase the incident energy by about a factor of 30. The experiment would be done using a Polarized Proton Target (PPT) employing radiation-doped NH{sup 3} beads and a 'local' cooling power of about 130 mW at 1/2{sup o} K. Such a target could be used with a beam intensity of 3 to 6 10{sup 10} protons per second, which is 1.5 to 3.0 10{sup 12} protons per pulse with Fermilab's 50 sec rep rate. This high beam intensity would allow good measurements out to about P{sub {perpendicular}}{sup 2} = 10 (GeV/c){sup 2} where the p+p {yields} p+p cross section is quite small. We propose to run in an underground target station such as P-West, which is ideally suited for such a high-P{sub {perpendicular}}{sup 2} elastic scattering experiment. We would use a double-arm spectrometer consisting of magnets with considerable bending power and high ...
Date: March 7, 1986
Creator: Court, G. R.; Crabb, D. G.; Krisch, A. D.; Lin, A. M. T.; Raymond, R. S.; Roser, T. et al.
Partner: UNT Libraries Government Documents Department