CYCLOTRON FUNCTION :

        To accelerate an H-minus ion beam, from 300 KeV to a maximum of 520 MeV in order to extract simultaneous proton beams
        at various energies and currents, into numerous beamlines, for delivery to targets for the designated experiments.

The  CYCLOTRON  with lid raised           INSIDE  the  520 MeV  CYCLOTRON  

Cost : The cyclotron and its associated systems cost about $12,000,000 (1974 CDN dollars)

Beam first extracted : 15 December 1974.

Peak intensity : 400 uA peak at 50% duty cycle achieved June, 1987.

Typical Operating Currents :

• Beamline 1A  : 140 uA @ 500 MeV
• Beamline 2A  :   70 uA @ 500 MeV
• Beamline 2C1 :    6 nA @ 110 Mev
• Beamline 2C4 :  95 uA @   83 MeV
• Beamline 4A  :   10 uA @ 200 - 500 MeV (currently decomissioned)
• Beamline 4B  :   10 nA @ 200 - 500 MeV (currently decomissioned)

Beam delivered : 16,000,000 microamp-hours to March 2010.

CYCLOTRON   COMPONENTS

VACUUM TANK : Defines the volume where the beam can be accelerated in a very good vacuum (reduces air molecule collisions).

• Diameter : about 56 feet (almost round: 670 inches to 704 inches) (about 17.9m diameter, or min/max dia. 1702cm - 1788cm)
• Area (top or bottom) : ~363,350 square inches or ~2,523 square feet (~235 square meters)
• Height : 18 inches (46cm) when closed
• Volume : 6,540,300 cubic inches or 3,785 cubic feet or 107 cubic meters
• Floor and Lid : 7/8 inch (2.2cm) 316 stainless steel (non-magnetic)
• Sides : 1-3/8 inch (3.5cm) 316 SS with 4-inch (10.1cm) midplane only 1/32 inch (0.8mm) thick, periodically supported by double-wall channels about 1/16 inch (1.6mm) each wall.
• Seal : Double rubber seal at edge of lid with the space between the seals pumped out seperately from the tank.
• Pumping system : Six cryogenic pumps, two turbo-molecular pumps, two 35-ft (10.6m) cryopanels (each has both 77K & 20K lines).
• Pressure achieved : Less than 5 x 10-8 torr (0.00000000006 of 1 atmosphere)
• Atmospheric load : 2660 tons (2,400,000 kg.) pushing down on the lid and the same pushing up on the bottom. The tank is held apart by the center post, tank wall and 664 1.5-inch (3.8cm) diameter tie-rods (332 on the tank floor and 332 on the lid), resulting in about 7 tons (6350kg) of tensile force on each tie-rod. The centre post and tank wall take up the remainder of the load.

ACCELERATION SYSTEM :

• Type : Resonant RF cavity , transverse-magnetic (TM), push-pull
• Number of DEES : 2 Main (180 degrees apart). (RF Boosters are possible.) 2 accelerating gaps in RF Booster. First RF booster used for normal beam delivery Feb/92.
• Resonator segments : 80 , (10 in each of 4 upper and 4 lower quadrants)
• Beam aperture : 8 centimeters
• Tuning :
  • Coarse : mechanical adjustment of segment electrodes
  • Fine: cooling water pressure (Bourdon effect)
• Operating frequency: nominally 23.0550 MHz (23.0380 MHz - 23.0710 MHz)
• Operating voltage : Typically 93 kV (hot-arm-to-ground)
• Acclerator voltage: typically 186 kV (DEE-to-DEE) plus a contribution of 100-200kV from the RF Booster (RFB) at higher energies
• Voltage stability : ~ 1 part in 10**4
• Beam phase stability : +/- 2 degrees
• RF freq/orbit freq : 5 . (must be ODD for cyclotron to accelerate beam. (harmonic number) The RF goes through 5 full cycles for every orbit of the beam.)
• Main RF power input : typically 1 MW from 4 x 500kW Push-Pull Power Amplifiers
• RF reflected power : typically 1 to 10 KW
• Beam loading : ~85 kW when simultaneously delivering 150 microamps to BL1, 50 microamps to BL2, and 10 microamps to BL4.
• Frequency modulation : has been used experimentally to stabilize beam phase.

INJECTION SYSTEM :

Injection beam: H- ions. An "H-" beam is composed of hydrogen (1 proton (positive) & 1 electron (negative)) with 1 electron added. This results in an overall negative charge. Thus "H-" .

• Voltage: 300 kV produced by a magnetically coupled Cockroft-Walton voltage multiplier. Thus each H- ion is accelerated to an energy of 300kV.
• Beam Transport :
  • 6" high vacuum beampipe
  • electrostatic quadrupole focusing elements
  • electrostatic steering elements
• Ion Sources :
  • Source 1 : high-intensity CUSP
  • Source 2 : low intensity post-polaraized Duo-plasmatron (presently decommissioned)
  • Source 3 : high-intensity CUSP (presently not available)
  • Source 4 : med-intensity laser-pumped polarized (presently decommissioned)

BEAM EXTRACTION SYSTEM :

• Method: electron stripping. H- ions are changed into protons (H+ ions) by passing them through a thin carbon foil or wire. The ion's two electrons are stripped off, while the much heavier protons pass through and, being positively charged, curve the opposite way (CW) from the negatively charged circulating ions (CCW). Thus the protons curve out of the cyclotron into the primary beamlines.
• Multiple simultaneous beams: Foils or wires narrower than the beam diameter may be used to intercept and extract a portion of the beam below full energy. By placing these devices at suitable locations it is possible to direct proton beams of different energies and currents into up to four external beam lines simultaneously.
• Stripping foil types : carbon (pyrolytic graphite), typically 0.75" (19mm) high and of various widths from 0.015" (4mm) to 0.75" (19mm). The foils are typically 0.00044" (11 microns) thick. In addition wire "foils" of 0.001" (25 microns) diameter are also used. All foils are supported on a stainless-steel or phosphor-bronze frame.
• Extraction efficiency : 100 percent
• Energy range :
  • BL1A   : 180 to 520 MeV (220 to 312 inches)
  • BL1B   : 180 to 500 MeV (220 to 310 inches)
  • BL2A   :   near 500 MeV
  • BL2C1 :   65 to 120 MeV (147 inches to 180 inches)
  • BL2C4 :   70 to 116 MeV (150 inches to 177 inches)
  • BL4      : 180 to 520 MeV (220 to 312 inches) (currently decomissioned)
• Energy spread : extracted beam has typical energy spread of 1MeV. with resolution down to 100keV with MRS operation. (delta-E/E is 0.3 percent)
• Emittance : 3 pi-millimeter-milliradians (both axial and radial)
• Pulse width :
  • microstructure: >25 degrees of the RF cycle (typically 4 nsec)
  • macrostructure : 99% on 1% off @ 1 kilohertz pulser rate
• Number of Extraction horns : 4, in Valleys 1, 2, 4 & 5. None possible in 3 & 6 since the resonator flux guides which couple the top & bottom segments would block the path of the extracted beam.
  (Extraction horns and their corresponding beamlines are numbered after the magnet valley in which they are located).
• Number of extraction ports: Four currently in use - 1, 2A, 2C and 4. Extraction ports 2A (high energy) and 2C (low energy) are both on extraction horn 2.
• Number of extraction-probe ports in use : 3 , Extraction 1, 2A and 4. Extraction probe 5 port currently houses High-Energy beam probe "HE3".
• Typical extraction split ratio of beam currents for simultaneously extracted beams :
  • Beamline 1 to Beamline 2A - 1:1
  • Beamline 1 to Beamline 2C4 - 1:1
  • Beamline 1 to Beamline 2C1 - ~ 1:50,000
  • Beamline 1 to Beamline 4(A/B) - 1:10 ~ 1:25,000

BEAMLINES :

Vacuum pipe material : non-magnetic stainless steel

Vacuum seals : double-knife-edge steel on indium. Other forms are used for temporary setups

Magnets : Front end elements are radiation-hard and remotely handlable. The conductors are directly cooled hollow copper tubes (cooling water flows through the conductors). Noteable exceptions are the combination magnets which are mounted on the extraction horns and guide the beam out of the cyclotron into the beamlines. Combination-magnet conductors are mineral-insulated and indirectly cooled. Water cooling is via a closed-circuit, low-conductivity, copper-only system. Magnet specifications are available in the Control-Room copy of the TRIUMF MAGNET INDEX which lists all the beamline magnets on the site and gives their specifications.

Vacuum system : There is some pumping from the cyclotron tank itself, beamline vacuum is primarily achieved by turbo-molecular pumps.

Beam tunes and currents: Both Achromatic and Dispersed tunes are possible:

• Beamline 1A operates primarily at 500 MeV up to 140uA
• Beamline 2A operates primarily at 500 MeV up to 100uA
• Beamline 2C1 operates at 74-116 MeV at a few nano-amps
• Beamline 2C4 operates primarily at 100 MeV up to 100uA
• Beamline 4A (currently decommissioned) operated up to 10uA
• Beamline 4B (currently decommissioned) operated up to 500nA

CYCLOTRON LOCATION :   " THE  VAULT "

Dimensions : 100ft (30.5m) x 100ft x 39ft (11.9m) high (from floor to underside of roof beams).

• Walls: The east, west and south walls are 16ft (4.9m) thick concrete. The north wall is thinner as it is backed up by a 30' thick earth berm.
  
  
• Roof : 132 beams in 3 layers separated & air-sealed by heavy polyethylene film. Each beam has the following approximate dimensions:
  • length 93.5 - 97.5 feet (29.75m)
  • width : 2.5 feet (.76m)
  • depth : 5.3 feet (1.6m)
  • weight : ~97 tons (88,000 kg) - Total weight of roof : ~ 12,500 tons (113,500,000 kg)
  • material : concrete specially reinforced, pre- & post-tensioned for strength and minimum sag. Manufactured on site.
  These roof beams are supported only at each end on a step structure of 1ft (0.3m) wide ledges. Thus the lower roof beams are the shortest at 93.5ft, the middle ones are 95.5ft and the top layer 97.5ft. The total thickness of the roof shielding is 16ft (4.9m) which is the same as the Vault east, west and south walls.

  This shielding prevents hazardous forms of radiation (neutrons, protons, gamma and beta rays), produced when the cyclotron is operating, from escaping the Vault.
  

• Floor :
  • 8ft (2.4m) to 17ft (5.2m) thick high-strength (6000 psi) concrete with lots of extra heavy, pre-welded reinforcing steel. The magnet-sector support columns are potted in large, heavy steel containers set into the floor, thus providing 0.1g earthquake protection. The cyclotron, its supporting structure, and shielding blocks rest on a 12-sided "circular" steel reinforced concrete pad, ~ 65 feet in diameter, which varies in thickness from 8 feet at the edge to 17 feet at the centre. This pad is horizontally separated from the surrounding floor, which is 8 feet thick, by a 1 inch thick high density cork layer. This extremely rigid pad thus surrounded by the floor provides a good level of protection from possible earthquake-induced misalignment or damage.

Ventilation :

Two large (~3K cu.ft/min.) blowers (one on-line, one standby) exhaust air from the vault through HEPA filters, thus ensuring that the Vault is always kept at a negative pressure and that any active
particles are contained.

Local Cyclotron Shielding :

More than 200 moveable high-density concrete blocks surround the cyclotron to shield work areas. These blocks were constructed with metallic aggregate (iron ore from Texada Island B.C.) and are ~40% heavier than normal concrete (5,400 v.s. 4,000 lbs/cu.yd.) These blocks contain a high percentage of water to trap neutrons and heavy elements to stop gammas.

Elevating System :

Twelve jack columns each comprise a twenty-horsepower electric motor, two Highfield 60:1 gear-reduction boxes and two jack screws. These jacks elevate the "spider" support structure which thereby lifts the upper magnet halves, tank lid and internal components, a total weight of ~2000 tons. The time it takes for the elevating system to reach the 48-inch (122cm) upper limit, is 35 minutes.

Each pair of jacks has a servo which reads the amount the jack has moved. When the lid is travelling, each of the 12 servos is constantly compared to a master servo which is being driven by a small motor at a rate which is just a bit slower than the jacking system.

When a jack servo gets 0.03 inch ahead of the master servo, the elevating control system shuts off the respective motor until the master servo catches up. The entire top half of the cyclotron (~2000 tons) can be raised 48 inches with no more than + or - 0.050 inches difference between the jacks. Interlocks stop the entire system if any jack goes out of range.

SAFETY SYSTEM :

Lockup : The SAFETY SYSTEM will not allow beam to be injected until the Vault is secured. This is accomplished by a "deadman-switch" and "watchman-station" lockup search procedure. Two qualified persons are required to perform this task. All access doors must first be closed leaving these two people inside the Vault. One person holds the dead-man switch while the other goes on a pre-determined route and checks that no personnel are left in the vicinity Pushing buttons to activate numerous watchman stations along the route ensures that the entire area is searched. When all the stations have thus been activated, the two lockup personnel and anyone found in the vault must then leave the Vault by a pre-determined door. With no one left in the Vault, this door is then locked, its key removed and inserted into the Vault Area Safety Unit (ASU) where it is automatically locked in place. Subsequently this key may only be released from the ASU, only from the Main Control room, and only if the Central Safety System logic is satisfied that it would be safe to do so.

If the searach procedure was to be interrupted by someone opening a door and entering the Vault, or if the first member of the lock-up pair were to release the dead-man switch, or if the lockup were to take too long, the lockup sequence would automatically be aborted, and the entire lockup sequence must be repeated.
After a successful lockup, the "Secured" sequence begins. Pushing a button on the Area Safety Unit causes an automated announcement and warning horn to sound in the Vault for 1 minute. Anyone in the locked-up area hearing this is able to prevent the area from becoming "Secured" by pressing any one of many Emergency Trip buttons. This person must then leave the area immediately, using a breakbolt on any exit door if necessary. This would also cause the vault to go unsecured. Only after a proper lockup and Secured sequence will the Central Safety System (CSS) allow beam to be injected into the Cyclotron.

Beamspill Monitors (BSM): There are numerous beamspill monitors continuously operating in the Vault that warn the Control Room if excessive beam should strike the cyclotron or beamline elements.
Some of these monitors will shut off the cyclotron if the spill reaches a pre-determined level. These BSM's are also used to measure the residual fields so that a determination can be made as to wether entry may be permitted or denied. There are also numerous monitors measuring neutron fields and air activation. The Control Room monitors and records all radiation measurements. All monitors are calibrated and tested at least once a year and critical monitors are done once every week during beam operation periods.

Surveys : Before any workers can do installation or maintenance in the Vault, the area is surveyed by Safety personnel and signs are posted. Every worker must carry a pocket dosimeter to record any radiation dose. Thus, the dose for each job may be predicted for the next occurance.

CCTV : During shutdowns and extended maintenance periods, television cameras are installed in the vault. Due to radiation considerations, the cameras must be removed during beam operation.

MISCELLANEOUS :
Drainage : The Main Accelerator Building is more than twenty feet (>5m) below the water table. Pumps continuously drain the subsurface ground water into the storm sewer system. In case of power failure, the pumps are powered by the emergency generator system.

EMERGENCY GENERATORS:
Many systems deemed critical for both personnel and facility safety, can be powered via the five generators on site: