AGS Ring Research Articles

A Method for Determining the Position, Angle and Other Injection Parameters of a Short Pulsed Beam in the Brookhaven Ags

injection parameters, a -2.4~~ pulse of H- is injected into the AGS and the resulting bunch of protons is observed with a PUE for approximately 40 turns around the machine. A schematic diagram of the PUE and associated electronics is shown in Fig. 1. The PUE consists of four plates and is located approximately one superperiod downstream of the injection region. As the proton bunch circles around the machine it produces in each plate a train of some 40 pulses, each pulse corresponding to the passage of the bunch through the PUE on a given turn. The signals from the upper and lower plates yield the vertical displacement of the bunch with respect to the beam pipe center, while the signals from the inner and outer plates yield the horizontal (radial) displacement. Since the period of revolution for a proton in the AGS is -4.8 ps at injection (200 MeV), a 2.4 us wide bunch of protons will produce in each plate pulses which are -2.4 ps wide and are separated from each other by -2.4 us. The pulse trains from the four plates are amplified (unity voltage gain) in the AGS ring, transmitted 1700 feet on coaxial cables, voltage amplified x10 and then digitized using LeCroy (liTR8837F) digitizers which sample the signals every 250 ns. The digitized data are analyzed with appropriate software to determine the amplitude of each pulse. If we let Anand B respectively be the amplitudes of the pulses from ;he upper and lower plates or from the outer and inner plates of the PUE on the nth

A System for High Field Pulsing and Demagnetizing of Multipole Magnets in the AGS

A system is considered where an unloaded ac generator is triggered to pulse an inductive load in a decaying train of oscillations. This is suitable for pulsing AGS ring multipoles where the required magnetic energy is a few kilojoules. The decaying oscillations serve to demagnetize the load. Since the output impedance of the generator is low and the magnetic coupling coefficient between stator and rotor is close to unity the short circuit currents are high and a significant amount of reactive energy is available for the load magnet.

Improvements in the measurement of electron diffusion coefficients by the light chamber technique

IMPROVEMENTS IN THE MEASUREMENT ETC. 451 once between the two electrodes, perhaps due to absorbed ions. This work-function difference has been measured by a series d.c. voltage and turned out to vary in the range of few mV up to some hundreds of mV, depending on the number of electron-ion pairs generated in any sampling process. Tipically, a workfunction difference of about 100 mV, at a pressure of 412 mm Hg, gives an apparent reduction of v of 17%. Therefore in the measurements we report in this paper, we use alternate clearing pulses. The pulses change polari ty every two samplings, as shown in Fig. 1. Besides, Sla v a b a b a b t ~ -;--Ta~ c -~ Fig. 1. Complete duty cycle: a represents the X-rays pulse, b the sampling amplification pulse, c the clearing field. in the measurements of rcf. (3) the observations of the decay of electron number were l imited to a range of few time constants, because high amplifications, that is high values of E/p, were excluded in tha t experiment by discharges on the electrodes (because of imperfection in the Ni-Cr layer) and near the lateral wall, where electric flux lines have a path partially in glass and partially in gas (s). tn the set of measurements w e report in this paper, discharges on the electrodes have been avoided by depositing a Sn02 layer (which is very uniform and resistent) before the subsequent Ni-Cr layer (Fig: 2). Discharges on the lateral wall were avoided by having a field less intense near the edge than in the center of the chamber. This has been achieved by fitting the electrical contacts at the center of the electrodes (Fig. 2) instead of near the edges (~), and by having a convenient electrode resistance ( _~ 1 k ~ between central Ag circle of 15ram diameter and peripheral Ag ring) which gives a convenient radial voltage drop during the transient amplification pulse.

Measurement ofp+p→π++dat High Momentum Transfers

Three measurements of the differential cross section for $p+p\ensuremath{\rightarrow}{\ensuremath{\pi}}^{+}+d$ have been made at the Brookhaven AGS, at incident laboratory momenta 11.6, 15.0, and 22.9 BeV/c and corresponding deuteron angles 55.7\ifmmode^\circ\else\textdegree\fi{}, 43.4\ifmmode^\circ\else\textdegree\fi{}, and 34.7\ifmmode^\circ\else\textdegree\fi{} in the center-of-mass system. The internal proton beam was made to strike a polyethylene target, and coincidences were taken between the outgoing pion and deuteron by placing counter telescopes both inside and outside the AGS ring. Both particles were momentum analyzed and the deuteron was identified by the use of a gas-filled differential Cerenkov counter. The pion was identified by time of flight. The total number of protons incident on the target was obtained by radiochemical analysis of the ${\mathrm{Be}}^{7}$ spallation product from carbon. Differential cross sections in the region ${10}^{\ensuremath{-}35}$ to ${10}^{\ensuremath{-}34}$ ${\mathrm{cm}}^{2}$/sr in the c.m. system were obtained. Our cross sections are \ensuremath{\sim}${10}^{4}$ times smaller than other measurements at lower energies and smaller angles; we conclude that this process decreases rapidly both with increasing energy and with increasing c.m. angle.