• Proposal to AEC for 500 MeV Linac


  • Funding of 400 MeV Linac authorized (December 1966)


  • Middleton site acquired
  • Start of construction authorized by AEC-New York Operations Office (April 1967)
  • Begin: Building construction (September 1967). Beam switchyard design. Center-line waveguide design (to cope with beam
blowup problem demonstrated at SLAC)
  • Let: Contract for transmitters (Energy Systems, Inc.);Contract for accelerator RF peripherals (SLAC)
  • Make decision to limit experimental program to electron scattering


  • Let contract for accelerator waveguide (Varian)
  • Begin design details energy loss spectrometer, ELSSY
  • Begin design details and specify water, vacuum, electrical systems design
  • Pursue Litton switchtube difficulty and design change requirements


  • Building occupied. Begin utilities, vacuum, water systems installation
  • Complete injector design and initial testing - MIT campus


  • Accelerator waveguide construction completed and delivered to site; begin accelerator assembly
  • Prototype transmitter completed, delivered to site, assembled for acceptance testing
  • Let contract for energy loss spectrometer work
  • Demonstrated pre-injector pulsed beam performance (440 keV, 4000+ pps, > 50 milliamps peak, > 20 µsec)


  • Transmitter prototype accepted
  • Begin assembly balance of transmitters; begin installation of beam switchyard
  • Let spectrometer hardware and power supply contracts (Lukens, Grumman, Bath Iron Works, Alpha)
  • Demonstrate injector 7.5 MeV beam and 100 MeV accelerated beam


  • Complete assembly of full linear accelerator centerline; mechanical, electrical assembly of RF transmitters; implementation of basic control system
  • Complete basic beam transport system to straight-through 14° and Spectrometer Room beam ports
  • Spectrometer power supply delivered and assembled
  • Demonstrate 126 MeV accelerated beam (delta p/p = 0.2% for 80% of beam)
  • Formal establishment of User's Organization (first Chairman, H. Crannell)


  • Demonstrate 1% RF 48 hour endurance operation (170 MeV, 3 transmitter operation)
  • Accelerator brought to 400 MeV capability in preparation for January 1974 demonstration
  • 14° beam line implemented and installed first phase gamma-pi experiment
  • Carried through horizontal assembly of energy loss high resolution spectrometer magnet and performed magnetic measurements
  • Installation underway of spectrometer peripherals, electrical, water, vacuum systems: spectrometer carriage, focal plane array, target chamber, remaining vacuum systems, etc., under construction
  • Dual PDP 11/45 computer data analysis system acquisition initiated


  • Brief, low duty ratio run of full accelerator, 5 transmitters, 406 MeV: ~ 1 µA beam current to 14° area
  • Vertical assembly of high resolution spectrometer completed
  • 100 hours of ~ 1 µA beam at 125 to 200 MeV energy delivered to first phase gamma-pi experiment


  • High resolution spectrometer operating in the "energy loss" mode achieved an unprecedented 1.1 x 10**-4 resolution
  • First 16O(gamma, p) data obtained


  • Development of vertical drift chambers for the electron spectrometer completed. The new system represented a major advance in the instrumentation of spectrometer focal plane systems
  • Construction completed on a fixed angle magnetic spectrometer in the 14° area for the study of the (gamma, pi±) reaction


  • 180° scattering facility installed and used for physics experiments
  • Expansion of laboratory facilities authorized
  • Fixed angle 250 MeV pi° detector for experiments in the 14° area


  • Large diameter beam dumping system installed at the high resolution electron scattering facility


  • South Hall and new buildings completed
  • Authorization received to construct a beam recirculator to increase maximum beam energy from 410 MeV to 750 MeV
  • Authorization received by Yale to design and build the polarized source for Bates


  • First electron beam put into the South Hall


  • Opening angle pi° spectrometer operational and taking data


  • Successful operation of the recirculator
  • Completion of construction of the One Hundred Inch Proton Spectrometer (OHIPS) and the Medium Energy Pion Spectrometer (MEPS)
  • First electron scattering and pion production experiments in the South Hall
  • Detailed design of BigBite spectrometer started


  • Fabrication and installation of sixth RF transmitter begun. Rework of modulators 2 through 5 begun. These projects will increase maximum energy to 1060 MeV
  • Extension of utility building begun
  • First (e,e'p) experiment


  • Polarized source moved from Yale to Bates for completion
  • TIRUS, a Bates-developed very high speed readout system, installed on MEPS


  • Completion of electron scattering experiments on tritium
  • Completion of construction of the BigBite spectrometer


  • Delivery of polarized electrons for experiments
  • High intensity pure photon beams available on Beam Line C


  • Deuteron tensor polarization experiment, 2H(e,e'd), with a high power liquid deuterium target
  • Initiation of advanced accelerator R&D for a pulse stretcher ring


  • Begin construction of the South Hall Stretcher Ring (SHR) with commissioning scheduled for 1992
  • Installation of the Moeller polarimeter on Beam Line B
  • Completion of the 12C Parity Violation Experiment


  • Begin construction of first generation out-of-plane magnetic spectrometer system


  • First measurements of quasi-elastic spin response: 3He(e,e')
  • First measurement using out-of-plane spectrometer system to obtain longitudinal-transverse interference response functions
  • Record high energy for an experiment (903 MeV), record high momentum transfer (42/fm**2), record low cross-section measurement (5 x 10**-40 cm**2/sr/MeV) for deuterium electrodisintegration at threshold


  • First measurement of fifth response function (C12 + deuteron), using polarized electrons and the out-of-plane spectrometer
  • Measurement of neutron charge form factor, via spin transfer to the neutron, using the neutron polarimeter


  • Beam successfully injected into the new Injection Line and transported through the West Straight Section of the SHR


  • Beam stored in SHR on first day of storage commissioning. Operation with full-turn injection of 40 µA (design maximum) demonstrated
  • Focal-plane proton polarimeter installed in OHIPS
  • Energy compression system commissioned; factor of ten easily obtained


  • Demonstrated resonant extraction from SHR
  • Began major upgrade program for linac and recirculator


  • SAMPLE experiment takes first data


  • BLAST funding approved


  • BLAST construction begins
  • Measurement of 3He magnetic form-factor to high momentum transfer
  • Ring commissioning demonstrates 5 minute lifetime of 60 mA stored current at 750 MeV
  • High intensity and quality SAMPLE beam developed


  • Measurement of n -> Delta transition with OOPS in both pi° and pi+ channels
  • SAMPLE data taking on Hydrogen
  • First stored Beam in SHR on Internal target


  • Over 200 mA in South Hall Ring
  • SAMPLE data taking on Deuterium


  • Completion and commissioning of OOPS spectrometer
  • VCS experiment: uses high duty factor beam and full OOPS spectrometer
  • SAMPLE results published in Science
  • OOPS running with extracted unpolarized CW beam, energies from 570 to 670 MeV, currents up to 10 μA, extraction efficiency 80 to 94%
  • 60 kV test setup for preparation and certification of polarized electron guns
  • Compton Polarimeter installed in SHR; back-scattered photons detected
  • Beam energy of 1 GeV achieved, with 14 mA peak current


  • OOPS running with extracted polarized CW beam, energy 950 MeV, current 10 μA, extraction efficiency 90%, duty factor 65%
  • Stored polarized beam in the SHR using Siberian Snake; 670 MeV, 50 mA, 30 minute lifetime
  • First observation of stored polarized electron beam spin flip using a prototype RF dipole
  • Fiber-coupled diode laser installed in polarized source


  • Completion of SAMPLE running at 125 MeV on deuterium
  • Completion of OOPS running
  • BLAST assembly and magnetic field mapping
  • Strained GaAs photocathode and diode laser used to produce highly polarized electron beam (>60%), stored in SHR; 850 MeV, 100 mA, 40 minute lifetime
  • 98% efficient spin flip achieved using a second RF dipole


  • Installation of BLAST neutron detectors
  • BLAST commissioning, with beam quality monitors used to optimize beam tune
  • Compton Polarimeter commissioned for operation with beam currents above 200 mA
  • Atomic Beam Source installed; first polarized internal target in the SHR


  • BLAST deuterium and hydrogen running. High target vector polarizations (>80%) achieved with installation of a collimator upstream of the target cell
  • Low-momentum compaction lattice used in SHR to reduce bunch length to 3.6 ps


  • BLAST data taking optimized with a second-level trigger and front-end buffering
  • Wire chamber and coincidence rates used to further improve beam tune. Beam lifetimes of 25 minutes with target gas achieved routinely
  • BLAST deuterium running completed
  • Coherent synchrotron radiation in SHR detected near 100 GHz
  • MIT takes ownership of the Bates facility