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Efficiency of Multiple Traversal Targets

Description: The efficiency of multiple traversal targets is defined as the probability that a proton dies by making a nuclear collision in the target rather than by hitting the limit of the synchrotron aperture. The efficiencies of Be, Al, Cu, and Pb targets are shown for 15 and 30-Bev protons in the Brooknaven AGS. Beryllium was found to be the most efficient. (M.C.G.)
Date: February 1, 1962
Creator: Courant, E. D.
Partner: UNT Libraries Government Documents Department

ACCELERATION OF POLARIZED PROTONS TO RELATIVISTIC ENERGIES

Description: Maintenance of poiarization of polarized protons in a linear accelerator is known to be feasible. Circular accelerators present a different problem, and the investigation of the interaction of orbit dynamics and particle polarization in general is undertaken. The equation of motion of the spin vector of a charged particle in a magnetic field as formulated by Bargman, Michel, and Telegdi is utilized in the study of depolarization for several accelerators. High values of depoiarization are obtained, and means for avoiding such depolarization are suggested. (D.C.W.)
Date: January 22, 1962
Creator: Courant, E D
Partner: UNT Libraries Government Documents Department

ACCELERATION OF DEUTERONS OR ALPHA PARTICLES IN THE AGS. Internal Report

Description: Possible experiments that could be performed at the Brookhaven alternating gradient synchrotron using highenergy deuterons and heavier nuclei are reviewed. Particular attention is given to production of high-energy neutrons by stripping. A brief analysis of changes needed to accelerate heavier nuclei reveals such modifications would not be prohibitive. (D.C.W.)
Date: December 18, 1962
Creator: Courant, E.D.
Partner: UNT Libraries Government Documents Department

Acceleration and storage of polarized beams

Description: A review is given of the theory of polarized beams in circular accelerators or storage rings, and the effects of depolarizing resonances, both steady state and passage through resonance, are discussed. The resonance width is evaluated, and the possibilities of accelerating polarized particles is considered. (PMA)
Date: January 1, 1977
Creator: Courant, E.D.
Partner: UNT Libraries Government Documents Department

Beam-beam interactions for bunched and unbunched beams

Description: The beam-beam interaction is analyzed in terms of Chirikov's stochasticity model. Stochastic blow-up occurs when the density of resonance regions in phase space becomes large, and Arnold diffusion is assumed to depend on the density parameter below the stochastic threshold. The relation between the density parameter and the tune shift epsilon is affected by bunching of the beam and also by variations in the strengths of several interaction regions and by beam misalignment. It is seen that bunching can reduce the tolerable epsilon by as much as an order of magnitude in proton storage rings.
Date: January 1, 1980
Creator: Courant, E D
Partner: UNT Libraries Government Documents Department

Possibilities of polarized protons in Sp anti p S and other high energy hadron colliders

Description: The requirements for collisions with polarized protons in hadron colliders above 200 GeV are listed and briefly discussed. Particular attention is given to the use of the ''Siberan snake'' to eliminate depolarizing resonances, which occur when the spin precession frequency equals a frequency contained in the spectrum of the field seen by the beam. The Siberian snake is a device which makes the spin precession frequency essentially constant by using spin rotators, which precess the spin by 180/sup 0/ about either the longitudinal or transverse horizontal axis. It is concluded that operation with polarized protons should be possible at all the high energy hadron colliders. (LEW)
Date: January 1, 1984
Creator: Courant, E.D.
Partner: UNT Libraries Government Documents Department

Performance characteristics of ISABELLE with Fermilab magnets

Description: If ISABELLE were to be built with FNAL magnets instead of the BNL magnets (or some other large-aperture variant), the luminosity in Phase I would be down from the standard value by a factor of around 10 to 2.3 x 10/sup 31/, which is still a very respectable figure with which one could surely do a great deal of interesting physics. Adding a booster (Phase II) would restore the performance to the level originally planned. Intermediate performance could be obtained by alternate injection schemes requiring AGS modifications (Phase IA).
Date: January 1, 1981
Creator: Courant, E.D.
Partner: UNT Libraries Government Documents Department

Polarized proton acceleration

Description: The question of whether polarized beams of 12 GeV or, preferably, higher energy can be produced at other existing or planned accelerators is explored. Sources of polarized H/sup -/ ions suitable for injection into accelerators appear to be feasible with intensities in the milliampere range (an order of magnitude better than present performance at Argonne). This would be sufficient to produce polarized beams of intensities comparable (though somewhat weaker) to those of unpolarized beams in high energy accelerators and luminosities not more than a factor of about 10 lower than those for unpolarized beams in storage rings, such as the CERN ISR or ISABELLE, the 400 GeV storage accelerator system now under design at BNL. The major question, then, is whether it is possible to maintain polarization in these accelerators during the acceleration process and during storage in a storage ring.
Date: January 16, 1978
Creator: Courant, E.D.
Partner: UNT Libraries Government Documents Department

Helical Siberian snakes

Description: To eliminate spin resonances in circular accelerators ''Siberian Snakes'' may be inserted at one or more azimuths in such a way that the overall spin precession tune ..nu../sub s/ equals 1/2. A snake is a sequence of horizontal and vertical deflection magnets whose overall effect is to rotate the spin by ..pi.. about an axis in the plane of the orbit, either longitudinal or transverse or any angle /var phi/ in between. At the same time the magnets of the snake should be arranged so as to produce zero net deflection and displacement of the particle orbit. We investigate here how the orbit deflections can be made small by using helical deflecting magnets rather than discrete horizontal and vertical deflectors.
Date: January 1, 1988
Creator: Courant, E.D.
Partner: UNT Libraries Government Documents Department

Bunched-beam p--p/sup -/ and p--p collisions

Description: Collisions between bunched beams of protons and/or antiprotons are studied. For simplicity, it is assumed that the bunches collide head-on, and that the two beams have the same number of particles N and rms beam radii sigma/sub x/ and sigma/sub y/ at the crossing point.
Date: January 1, 1978
Creator: Courant, E.D. & Keil, E.
Partner: UNT Libraries Government Documents Department

Transverse resistive wall instability of an off-axis ribbon beam in a circular chamber

Description: High energy proton storage rings are designed to make maximal use of the available vacuum chamber aperture. This is dictated primarily by economic considerations. The accumulation of current in a typical high energy ring creates a rather unusual beam configuration: in particular, a ribbon beam in a circular chamber set well off the central axis. The result is an enhanced resistive wall instability. This could be anticipated from the strong dependence of the current threshold on the chamber radius for a centered beam. For an off-centered beam, one might expect that the relevant replacement for the radius would be the distance of closest approach. The case of a wide ribbon-type beam is treated. The current threshold is obtained as a solution to a coupled oscillator eigenvalue problem. When the beam is small as occurs near the beginning of current stack formation, the problem is reduced to a dispersion relation. Results are expressed in terms of ISABELLE parameters. Some conclusions relevant to the ISABELLE design are presented.
Date: June 1, 1978
Creator: Courant, E.D. & Month, M.
Partner: UNT Libraries Government Documents Department

Hybrid helical snakes and rotators for RHIC

Description: The spin rotators and Siberian snakes presently envisaged for RHIC utilize helical dipole magnets. The snakes and the rotators each consist of four helices, each with a full twist (360{degrees}) of the field. Here we investigate an alternate layout, namely combinations of helical and pure bending magnet, and show that this may have advantages.
Date: June 13, 1995
Creator: Courant, E.D.
Partner: UNT Libraries Government Documents Department

Possibility of Polarized Beams at the AGS

Description: A two week study was held at Brookhaven this summer to investigate polarized proton acceleration at the AGS in more detail and to produce a preliminary design and cost estimate. The Brookhaven study discovered no new problems which cannot be solved. A polarized proton ion source of the H/sup -/ type is preferred, which could yield pulses of 75% polarized H/sup -/ ions with an intensity of 10 to 100 ..mu..amp and a length of 1 to 3 msec. Upon injection this would result in an AGS intensity of 3 x 10/sup 10/ to 10/sup 12/ polarized protons per pulse which, together with the 2 sec repetition rate and the high extraction efficiency of the AGS, would yield an extracted beam intensity 5 to 150 times larger than that of the ZGS. Twelve new pulsed tune-shift quadrupoles will be necessary to jump the intrinsic resonances while the existing 96 correction dipoles can be used to tune out the imperfection harmonics. Most of the polarization monitors necessary are simply extensions of existing polarimeters; however, a fast internal polarimeter with an associated thin internal target would be useful for rapid tuning during the acceleration cycle. With these modifications it should be possible to accelerate polarized protons through the 8 intrinsic and 47 imperfection resonances in the AGS up to 23 GeV/c by late 1980. Although no decision has yet been reached with regard to the implementation of such a program, it is presently being considered together with other options for future AGS operation.
Date: 1978~
Creator: Courant, E. D. & Ruth, R. D.
Partner: UNT Libraries Government Documents Department

Acceleration of polarized protons in circular accelerators

Description: The theory of depolarization in circular accelerators is presented. The spin equation is first expressed in terms of the particle orbit and then converted to the equivalent spinor equation. The spinor equation is then solved for three different situations: (1) a beam on a flat top near a resonance, (2) uniform acceleration through an isolated resonance, and (3) a model of a fast resonance jump. Finally, the depolarization coefficient, epsilon, is calculated in terms of properties of the particle orbit and the results are applied to a calculation of depolarization in the AGS.
Date: September 12, 1980
Creator: Courant, E.D. & Ruth, R.D.
Partner: UNT Libraries Government Documents Department

The evolution of high energy accelerators

Description: Accelerators have been devised and built for two reasons: In the first place, by physicists who needed high energy particles in order to have a means to explore the interactions between particles that probe the fundamental elementary forces of nature. And conversely, sometimes accelerator builders produce new machines for higher energy than ever before just because it can be done, and then challenge potential users to make new discoveries with the new means at hand. These two approaches or motivations have gone hand in hand. This lecture traces how high energy particle accelerators have grown from tools used for esoteric small-scale experiments to the gigantic projects of today. So far all the really high-energy machines built and planned in the world--except the SLC--have been ring accelerators and storage rings using the strong-focusing method. But this method has not removed the energy limit, it has only pushed it higher. It would seem unlikely that one can go beyond the Large Hadron Collider (LHC)--but in fact a workshop was held in Sicily in November 1991, concerned with the question of extrapolating to 100 TeV. Other acceleration and beam-forming methods are now being discussed--collective fields, laser acceleration, wake-field accelerators etc., all aimed primarily at making linear colliders possible and more attractive than with present radiofrequency methods. So far it is not entirely clear which of these schemes will dominate particle physics in the future--maybe something that has not been thought of as yet.
Date: August 1, 1994
Creator: Courant, E. D.
Partner: UNT Libraries Government Documents Department