ARIEL 2008-09 (in 750-1000 words … Actually 1400)

Introduction

The ARIEL project has the long term aim to triple the beam delivery to ISAC experiments. To achieve this, the following items are being constructed (see figure 1) over a 10 year time scale:

  • An 50 MeV 10mA electron linac (e-linac) housed in the existing proton hall
  • New ARIEL isotope production hall housing:
  • Two targets:
  • 500kW electron target
  • Proton/electron target
  • Possible RF separator to allow simultaneous electron beams on both targets
  • Two front-end systems to deliver two RIB beams to ISAC experimental halls
  • New ARIEL tunnel to connect the main cyclotron building to the isotope production hall, housing two new beam lines to transport beams to the new ARIEL isotope production hall:
  • 50 MeV 10mA electron beam from the new e-linac
  • 450MeV 100µA proton beam from the TRIUMF cyclotron

The e-linac is designed to allow an upgrade path for a an energy recovery ring, in the existing proton hall, that would drive a free electron laser.

Overview of Progress 2008-9

The era started with the writing of the TRIUMF 5 year plan, which was completed in June 2008. This defined the project in two stages, where the initial stage (first 5 years) provided a proton and an electron beam onto a single target, along with a single front-end. And a second stage (second five years) provided an additional electron target, along with a second front-end. The project also got its name,Advanced Rare IsotopE Laboratory (ARIEL), during the preparation of the 5 year plan document.

The project then quickly moved forward into a successful request for CFI funding for an e-linac with an electron beam line to a target. The target and frontend were not requested in this CFI request and were assumed to be funded from TRIUMF’s NRC contribution. This CFI requestwas submitted in October 2008 by Prof. Dean Karlen (U. Victoria) and he obtained the notification of a positive response from CFI in July 2009. The preparations for this request required an independent cost analysis of the ARIEL buildings, including the relocation for the stores and remote handling office buildings, and a detailed costing and schedule for the e-linac to be prepared.To release the CFI funds and start work on the e-linac two further hurdles had to be crossed: TRIUMFhad to obtain building funds from the BC Province, and had to have a successful five-year plan awarded from the Canadian Federal Government. These steps could not be concluded prior the Federal budget in spring 2010.

While awaiting this Federal and Provincial government funding ARIEL moved forward in two projects:

1)A joint project to jointly develop the ion source and capture cavities with the VECC institute (India),which had begun with discussions in January 2008, and was formally started withthe signing of anMoU agreement(see *** in this report). This allowed workto start on theARIEL e-linac injector along with an injector for the VECC institute.

2)An ARIEL team was setup to make the final decisions and move forward on engineering designs so that the project could move ahead fast when the CFI funds were released. The critical path for the project was identified to be the civil construction. So AECOM were retained to develop the civil construction concepts so that the civil engineering consultants could be hired within days of the release of the CFI funds.

Detailed progress of the ARIEL Team

Management

An organisation structure was setup with one sub-team for each major component and a Project Management Office (see figure 2). The ARIEL work breakdown structure(WBS) was defined and a manpower loaded schedule produced. Milestones were established, an open questions list made, and a risk analysis undertaken for the project.A start on an initiative for an equipment naming conventionwas made. The project was reviewed by an external Accelerator Advisory Committee(AAC) whoseinsightful recommendations were useful in guiding discussions during which the ARIEL group reached a consensus to move items from the “open questions” list to the “decisions” list.

e-linac and Beam Line

The e-linac design entered the detailed conceptual design stage, resolving a number of difficult and correlated design issues. This era started by defining the parameters required for the upgrade path for a free electron laser. Beam dynamics calculations for the e-linac were undertaken comparing the single 2-cell versus two 1-cell SC capture cavity. From these studies it was decided to use the two 1-cell SC capture cavity. In March 2009 Y.C. Chao introduced a genetic algorithm for global optimization of injector from the gun exit to the ICM exit, allowing studies to proceed to narrow the choices for layout. By October this effort had concluded with a baseline layout for the injector, with adequate space for diagnostics, and was adopted as a basis for the engineering design. This design had a 650 MHz buncher; SC capture cells β=0.7, 2nd cell β=1.0; and solenoid focusing.Meanwhile design work on magnets at DPACE produced preliminary magnet designs for the LEBT solenoids and dipole, and MEBT dipole. Beam optics studies concluded with a preliminary concept for electron beamline from e-linac to the east target with electrons and protons sharing final focus optics elements. This was then followed by a study to decide on a layout of the electron and proton beam lines in the tunnel. For access reasons this resulted in the lines being moved to the east side of the tunnel with the proton beam above the electron beam. To allow room for the electron beam the tunnel floor was lowered by 1 foot. Late fall 2009 studies included a detailed review of the Personnel Radiation Safety System proposal and Machine Protection System proposal with Kelly Mahoney (JLab), as well as presentations from Toshiba and CPI on klystrons. The klystron presentations were necessary because the supplier of the klystron specified in the CFI proposal had announced they were no longer manufacturing scientific klystrons. In December the AAC visited TRIUMF and recommendeda second separate injector for light source, noting that this would give complete independence of beam properties for fission and lightsource. They also recommend NC graded-beta capture section to avoid mechanical complexity of SC single cells and to speed the schedule. These and other recommendations aided design decisions in early 2010.

Target Station and Frontend

The target design during this era was advanced to a detailed conceptual design suitable for engineering design. To aid the optimization of the target for both protons and electrons, a decision was made to have the proton beam and electron beam impinge on target at right angles.An extensive design of the target hall and hot cell complex was undertaken, with full consideration made of personnel access to the building being undertaken for the first time. In the target hall a design was adopted where the RIB beam line elements are installed and maintained from above using the overhead crane. This allows a close packed shielding design to be adopted, thus reducing the neutron fields in the RIB building (an issue that has created considerable difficultly at the existing ISAC target).

A detailed layout of the front end systems was developed and space allocated for future upgrades, power supplies and services.

ARIEL Building Complex

The goal in this era was to be ready for the design consultants that would provide final construction drawings. For this Gary Ridout of AECOM was retained to enhance our construction design capability.

Design of the main ARIEL building was sub-divided into teams for:

  • E-linac vault
  • Tunnel
  • Target Hall
  • RIB section

Extensive studies of radiation shielding requirements were made for all the above areas. Requirements for services were detailed, and initial room data sheets were prepared. Studies were undertaken to specify the shoring requirements so that adjacent buildings would not be compromised by the civil construction. Egress requirements were considered in detail and a plan of suitably located entrances and exits designed.

In addition studies were undertaken for:

  • Stores building
  • New personnel entrance through the TRIUMF radiation fence under the MOB auditorium

A revised cost estimate was undertaken in early 2010, replacing the earlier 2008 estimate for the initial CFI submission.