[en] The MIT-Bates SHR, a 190 m long race track shaped electron storage ring with a 9.144m bending radius, is designed for nuclear physics experiments using two modes; the STORAGE mode with internal targets or the PULSE STRETCHER mode, which uses the 1/2 integer resonance and 2 ramped quadrupole magnets and 3 octupole magnets to (smoothly) extract the stored electrons of up to 1.0 GeV energy and 80 mA intensity over a period as short as 1 millisecond into the extraction line

[en] The MIT-Bates South Hall Ring (SHR) is an electron storage ring currently being commissioned. It is designed to operate at an rf frequency of 2856MHz with all the 1812 buckets filled and a circulating current of 80mA or greater. This leads to a small charge per bunch and the requirement for sensitive Beam Position Monitors (BPM). Since there will be 31 BPMs in the vacuum system, it is important to suppress trapped modes which may excite coupled bunch instabilities. The stripline BPM built for the SHR is a stainless steel structure, designed to be manufactured using standard machining techniques and commercial feedthroughs. With proper 50 Ohm matching and a geometry derived by insight from MAFIA calculations the BPM was constructed having a nearly flat rf response up through 10 GHz over the range of measurement. The stripline electronics allows the measurements within 0.1mm resolution, maintains orbital harmonics information past the 10th harmonic, and operates over a dynamic range of 1 ma to greater than 80 ma of beam current

[en] This report discusses the design and performance of 2 Ramped Quadrupoles (RQ). They are to be used to rapidly move the horizontal tune close to the half integer (7.5) for extraction of the up to 1.0 GeV electron beam stored in the SHR. The design chosen is an 8 conductor array symmetrically placed about the beam axis at ±15 degrees to the 4 axes and connected to produce a quadrupole field. The conductors are half imbedded in a ferrite shield assembly, outside a ceramic vacuum chamber, and when powered at 250 amperes produce a gradient of about 30 G/cm over the radius of 4.5 cm and along a 30 cm length. The ceramic chamber is internally conductively shielded to present a smooth bore surface for the S-band bunches, but allow the up to 20 kHz quadrupole field components to pass through the shield and influence the electron beam

[en] During the summers of 1998 and 1999, the polarized source at MIT delivered over 300 Coulombs of high quality polarized pulsed beam to the SAMPLE parity violation experiment. This success in beam delivery signified achievements of long lifetime for the Bates polarized source in both high average and high peak current regimes. The injection requirements of high polarization beams for the South Hall Ring will be discussed. They are relatively modest for the storage mode but very demanding in peak current and repetition rate for the extraction mode. Because of these requirements, a 60 keV test beam setup with a Mott polarimeter was constructed at Bates and will be described here. This setup is independent of the main accelerator and has provided a platform for R and D in photocathodes and high power lasers. New results will be presented on high peak current photoemission from strained GaAsP samples using fiber coupled diode array laser systems on this test setup. A brief report will be presented on the photoemission requirements of a future e-p Collider that is currently under discussion in the nuclear and particle physics community in the US

[en] The MIT-Bates Linear Accelerator Center is now in the commissioning stage for the New South Hall Ring (SHR). The SHR is a 1 GeV electron storage/stretcher ring with a 190 meter circumference and is designed for circulating beams of 80 mA. The SHR vacuum system was completed in January 1993 with commissioning starting in February. This paper describes the design of the vacuum system, hardware developed and operational performance during commissioning

[en] This report discusses the design, construction, testing and installation of 2 magnetic septa in the South Hall Ring Lattice for the injection and extraction of an electron beam of energies from 0.3 to 1.0 GeV. The report covers: Magnetic design and performance of the following; steel return frame, electrical coil design, power supply, vacuum vessel, supports, fiducialization, and magnetic measurements

[en] During the fall of 2001, the polarized source at MIT delivered over 140 Coulombs of high quality polarized beams to the SAMPLE-III 125 MeV parity violating experiment. Prior to the experiment, the source was reconfigured to deliver highly polarized beam using the new high power diode array laser system with large aperture beam optics, and a strained layer GaAsP photocathode from St. Petersburg. The results of these tests will be presented. The production run for SAMPLE-III was then carried out with a bulk GaAs and the Ar-Ti:Sapphire laser system. Since April of this year, the source has been delivering high polarization beams to the South Hall Ring for commissioning of the BLAST spectrometer. The stored current in the ring exceeds 100 mA. This is accomplished using the high power diode laser system and high-gradient-doped strained GaAsP photocathodes from Bandwidth Semiconductor Inc. tuned for 810 nm. The operational lifetime of the photocathode is excellent. A status report of the Bates polarized source and the operational experience of delivering high polarization beam to SHR will be presented

[en] A description of the MIT-Bates polarized electron source will be presented. Improvements to the polarized injector in recent years, including implementation of a multiple gun system, have made delivery of pulsed polarized beams for medium energy experiments routine and trouble-free. The spin orientation from the source is controlled by a Wien filter which has the added benefit of sweeping backstreaming positive ions away from the photocathode surface. The present challenge for the Bates polarized source is an unprecedented set of requirements on the stability and quality of the beam for the SAMPLE parity violation experiment now in progress, including limits on the source lifetime and helicity correlated beam position differences. The current status of the source lifetime is discussed. Recent results in laser beam position differences are presented as is a description of the diagnostics implemented on the laser transport line for fast and accurate measurements of these differences. Finally, we will discuss the plans for using a mode-locked laser system to achieve the higher laser power necessary for the South Hall Ring. copyright 1998 American Institute of Physics

[en] A proposed new high-luminosity electron–ion collider requires a polarized electron source of extremely high intensity. The MIT-Bates Laboratory, in collaboration with Brookhaven National Laboratory (BNL), has developed a new polarized electron gun that can be operated at currents in the mA range. This paper describes the design of the gun and beam line and also presents the results of the beam tests.

[en] A brief introduction to electron scattering with polarized beams as a precise tool for studying electromagnetic structure of nucleons and nuclei will be presented. The status of a parity violating experiment SAMPLE at Bates using a polarized beam to probe the strange quark content of proton will be reported. The polarized source at Bates as used for the SAMPLE experiment is described