A. D. Krisch

Energy dependence of spin-spin forces in 90°cm elastic p-p scattering

Abstract We measured d σ d t(90° cm ) for ↑+ p ↑→ p + p from 1.75 to 5.5 GeV/ c , using the Argonne zero-gradient synchrotron 70% polarized proton beam and a 70% polarized proton target. We found that the spin-spin correlation parameter. A nn , equals 60% at low energy, then drops sharply to about 10% near 3.5 GeV/ c , and remains constant up to 5.5 GeV/ c .

Simultaneous Measurement of 2 and 3 Spins in Proton Proton Elastic Scattering at 6-GeV/c

Abstract The elastic cross section for proton proton scattering at 6 GeV c was measured using a 70% polarized beam and a 75% polarized target at the Argonne ZGS. In the range P ⊥ 2 = 0.5 → 2.0( GeV c ) 2 we obtained small error measurements for the ↑↑, ↓↓ and ↑↓ initial spin states perpendicular to the scattering plane. At P⊥2 = 0.5 we also measured the recoil spin and found that the 5 different cross sections were very unequal.

Unexpected enhancements and reductions of rf spin resonance strengths

1098-4402= We recently analyzed all available data on spin-flipping stored beams of polarized protons, electrons, and deuterons. Fitting the modified Froissart-Stora equation to the measured polarization data after crossing an rf-induced spin resonance, we found 10–20-fold deviations from the depolarizing resonance strength equations used for many years. The polarization was typically manipulated by linearly sweeping the frequency of an rf dipole or rf solenoid through an rf-induced spin resonance; spin-flip efficiencies of up to 99:9% were obtained. The Lorentz invariance of an rf dipole’s transverse R Bdl and the weak energy dependence of its spin resonance strength E together imply that even a small rf dipole should allow efficient spin flipping in 100 GeVor even TeV storage rings; thus, it is important to understand these large deviations. Therefore, we recently studied the resonance strength deviations experimentally by varying the size and vertical betatron tune of a 2:1 GeV=c polarized proton beam stored in COSY. We found no dependence of E on beam size, but we did find almost 100-fold enhancements when the rf spin resonance was near an intrinsic spin resonance.

Commissioning the Polarized Beam in the AGS

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.

The Possibility of Acceleration of Polarized Protons in the Brookhaven AGS

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

Analyzing power measurements in high‐P2∥ p‐p elastic scattering

2 million one could obtain a polarized ion source, fast resonance jumping magnets, and 3 polarimeters which should allow acceleration of 1011 to 1012 polarized protons to 23 GeV/c with about 70% polarization or to 26 GeV/c with about 50% polarization.

Phenomena associated with the acceleration of polarized protons in circular accelerators

The analyzing power in 28 GeV/c proton/proton elastic scattering was measured at P2∥=5.95 and 6.56 (GeV/c)2 using a polarized proton target and an unpolarized proton beam at the Brookhaven National Laboratory AGS. Results indicate that the analyzing power, A, is rising sharply with P2∥.

Violent Collisions of Spinning Protons

A series of machine studies has been done with the zero Gradient Synchrotron (ZGS) at Argonne National Laboratory in order to better understand the phenomena associated with the acceleration of polarized protons and to determine the feasibility of acceleration to energies higher than the 12 GeV/c available at the ZGS. We also investigated the question of how long polarized protons can remain in storage rings without losing excessive polarization.The three topics investigated were: 1. The adiabatic crossing of an intrinsic depolarizing resonance. 2. The depolarization due to imperfection resonances. 3. The survival time of polarization on a long flattop.This paper is a preliminary report of these three investigations.

Effects of Depoiarizing Resonances on a Circuiating Beam of Poiarized Proions during Acceleration or Storage in a Synchrotron

High energy polarized proton beams and polarized proton targets have allowed good measurements of spin effects in high energy elastic proton-proton scattering. Since I have written about this subject several times In recent years, I will only briefly review the earlier work and refer the Interested reader to some rather detailed lectures.1

Proton-proton elastic scattering at 90°and structure within the proton

We have conducted a ser ies of exper iments with the polarized proton beam of the Zero Gradient Synchrotron (ZGS) at Argonne National Laboratory in order to: 1) Study the feasibility of adiabatically crossing intrinsic depolarizing resonances as an alternative to the fast tune-shift crossing presently used, 2) determine the amount of depolarization due to imperfection resonances which may be more important in alternating-gradient machines than in the ZGS, 3) determine whether polarized protons can be stored for times long enough to allow polarized colliding beam experiments. The results of these experiments will be presented.