A non-destructive internal emittance device has been built for the AGS, with separate units to measure the horizontal and vertical profiles of the circulating beam. Positive ions from collisions of the beam with background gas are collected in a 3-kV/cm electric field onto a 64-channel parallel strip detector. Because positive ions rather than electrons are collected, profile broadening due to space charge is small. Tests indicate that a quantitative, reproducible and accurate measurement of beam size throughout the acceleration cycle is provided.
The RHIC (Relativistic Heavy Ion Collider) Accelerator currently under construction at Brookhaven National Laboratory w i l l have large detectors at two of its six intersection regions. One of these detectors, known as STAR (Solenoidal Tracker At RHIC), weighs 1100 tons and is being built around a large solenoid magnet. The magnet is 7.32 m in diameter, 7.25 m long and utilizes three different sizes of room temperature aluminum coils. The magnet will operate with a field set from 0.25 T to 0.5 T and have a field uniformity of better than 1000 ppm over a portion of its interior region. This paper describes the magnet design, fabrication and assembly requirements and presents the current construction status.
Int rod 11 ctIon A beam scraper using a linear motor drive has been developed for use in the ACS at Brookhaven National Laboratory. the device is usud to measure bean size by moving a target to a predetermined locacion and measuring the intercepted beam uitli nearby loss monitors or by noting the decrease In Ch« circulating beam current. This device has excellent vacuum characteristics, ;is the motor and •cnaor colls are outside che vacuwn, coupled magnetically to the moving parts which are Inside. There are no bellows or dynamic seals required. The position-time profile is controlled by a closed-loop 8«rvo system which uses position feedback. Design Goals The old beum scrapers at the ACS, known as the "flip targets", have been used for bean size measurements and for cleaning up small amounts of beam halo. These tartful*, which are the descendants of Che Internal targets once used for the production of secondary beams, have several shortcomings. They hit a mechanical stop to determine their•position, stressing the target. This precludes the use of brittle refractory material for the target and thus limits the amount of beam that may be intercepted without melting the target. The motors that flip Che target into the beam are inside the vacuum and are expected to be a serious source of outgassing as the AGS vacuum Is improved.
Upton, New York 11973Two Lambertson-type injection magnets have &en designed, constructed and tested magnetically. One magnet is the mirror image of the other and each will serve as an injector in the rings of the Relativistic Heavy Ion Collider (RHIC) accelerators under construction at Brookhaven National Laboratory (BNL). To obtain the required field quality in the injected beam region and low stray fields in the circulating beam region of the magnet, an optimization study was performed using computer codes to provide solutions for a two and three dimensional model of the magnet. The calculations are compared to the magnetic field measurements taken in the injected and circulating beam regions mentioned above. Field inhomogeneities in the injected beam region were less than 6x104 for either measured or calculated B-fields. The magnetic-field strength in the circulating beam region was less than 0.1 Gauss (measured or calculated). A description of the mechanical design of the magnet as well as a detailed comparison of the measured magnetic fields to those calculated using the two and three dimensional computer codes is presented here.
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