Effect of Synchrotron Radiation in the Proposed 4-GeV Argonne Microtron
Synchrotron radiation in the sector magnets of the 4 GeV microtron designed at the Argonne National Laboratory produces a small but noticeable distortion of the closed orbits of the system and a very significant growth of the horizontal and longitudinal phase space emittances. Because of the small apertures in the three 25 meter linacs, it is important that the expected growth of the beam be calculated as accurately as possible. The dynamical problem has been solved using a computer program which follows the motions of individual electrons in the four dimensional horizontal and longitudinal phase space as they are accelerated in the system. In this paper the authors call attention to the fact that there are 3 long 28 m linac sections separated by sector magnets from 3 dispersion sections where the orbits for different energies are separated. The interaction of the linac rf systems with the synchrotron energy loss in the sector magnets produces different orbit effects in the downstream and upstream linac sector magnets. The average synchrotron radiation energy loss per sector magnet is given.
Particle diffusion from resonance islands in ALADDIN at SRC
The dynamics of the beam in the resonance islands was studied on the electron storage ring ALADDIN at the Synchrotron Radiation Center (SRC). We especially studied the horizontal third- and fourth-integral resonances driven by sextupole fields in the first and second order. A fast kicker was fired to kick the beam into one of the outboard stable islands. The beam took on a quasi-Gaussian distribution and slowly diffused out of the island. The diffusion rate and its dependence on the strengths of the driving sextupoles and the chromaticity sextupoles were measured by tracing the resonance peak of the betatron oscillation on the spectrum analyzer. Beam positions were also recorded through the data acquisition device which was clocked by a pulse-delay circuitry. Interesting results are shown and compared with numerical calculations.<<ETX>>
Monte carlo simulation of events with Drell-Yan lepton pairs from antiproton-proton collisions
The complete knowledge of the nucleon spin structure at leading twist requires also addressing the transverse spin distribution of quarks, or transversity, which is yet unexplored because of its chiral-odd nature. Transversity can be best extracted from single-spin asymmetries in fully polarized Drell-Yan processes with antiprotons, where valence contributions are involved anyway. Alternatively, in single-polarized Drell-Yan the transversity happens convoluted with another chiral-odd function, which is likely to be responsible for the well known (and yet unexplained) violation of the Lam-Tung sum rule in the corresponding unpolarized cross section. We present Monte Carlo simulations for the unpolarized and single-polarized Drell-Yan pp{sup ({up_arrow}}{sup )}{yields}{mu}{sup +}{mu}{sup -}X at different center-of-mass energies in both configurations where the antiproton beam hits a fixed proton target or it collides on another proton beam. The goal is to estimate the minimum number of events needed to extract the above chiral-odd distributions from future measurements at the high energy storage ring (HESR) at GSI. It is important to study the feasibility of such experiments at HESR in order to demonstrate that interesting spin physics can be explored already using unpolarized antiprotons.