Accelerator Operations
1. Introduction
The government of Canada has invested significantly in TRIUMF since its inception
which has enabled TRIUMF to achieve national and international recognition as
Canada’s national laboratory for nuclear and particle physics. TRIUMF is recognized as
a world leader in exotic radioactive ion beams produced at the ISAC Facility. TRIUMF
contributes significantly to medical applications and research through the Life Sciences
PET Program (TR13 cyclotron), the Proton Therapy Program to treat choroidal
melanomas (eye tumors) and proton irradiation of rubidium to produce strontium for
medical imaging generators. To achieve such results requires an organization of multidisciplined experts working and responding as a coherent team.
2. Proton Delivery
The success of TRIUMF programs depends on the ability to reliably deliver protons from
the 500 MeV cyclotron. Typically, the cyclotron, although over thirty years old, averages
an uptime of greater than 90% (2000 - 2007), the 15 year average is just under 90%.
500 MeV Cyclotron Uptime 1992-2007
100
90
80
70
60
50
40
30
20
Cyclotron Uptime (%)
10
0
1992
1993
1994
1995
1996
1997
1998
1999
2000
2001
2002
2003
2004
2005
2006
2007
Figure 1 Cyclotron uptime as a percentage of scheduled operational hours per year
Accelerator operation will expand under the new Five-year Plan to support the new
initiatives. The cyclotron intensity upgrade will allow higher injected H- intensities into
the cyclotron to support high intensity beams for four beamlines (BL1A, BL2A, BL2C
and BL4N). Although the potential for high intensity (400 μA) operation was
demonstrated in 1988, more recent development initiates have demonstrated that
accelerating higher beam intensities is realistic. In 2006 the cyclotron ran for an
extended period with a 20% increase in the nominal operating beam current.
The total mAhr charge per year has increased, on average, since ISAC has come on-line
with no corresponding increase in downtime demonstrating the cyclotron’s capacity to
deliver increased beam currents. The total charge delivered in 2007 was reduced by
approximately 80-100 mAhr due to the upgrade and re-commissioning activities at the
BL2C4 solid target facility. The total charge to BL2A (green) for ISAC has more than
doubled in the past four years.
Annual Total Charge Delivery 1992-2007
800
700
Charge (mAhrs)
600
500
400
300
200
100
BL1A
BL2C4
BL2A
0
1992
1993
1994
1995
1996
1997
1998
1999
2000
2001
2002
2003
2004
2005
2006
2007
Year
Figure 2 Total annual proton charge (mAhrs) delivered to three beam lines
Figure 3 shows the percentage of charge delivered to charge scheduled for BL1A. The
15 year average is 95.5% although the cyclotron uptime during this period averages about
90%. Similar beam charge delivery efficiency is available the ISAC Facilities.
BL1A Charge
110
100
90
80
70
60
50
40
30
BL1A Charge
20
10
0
1992
1993
1994
1995
1996
1997
1998
1999
2000
2001
2002
2003
2004
2005
2006
2007
Year
Figure 3 BL1A charge in mAhrs delivered as a percentage of charge scheduled per year
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3. Radioactive Ion Beam Delivery
The ISAC facility has an Off-Line Ion Source (OLIS) that produces various species of
non-radioactive charged particles which can be directed to low energy experiments, or
accelerated through the Radio Frequency Quadruple (RFQ), Drift Tube Linac (DTL) and
Super Conducting Radio Frequency Linac (SCRF). Since Radioactive Ion Beams (RIB)
are of low intensities and are difficult to measure, OLIS beam is required to produce
equivalent charge to mass ratio beams for accelerator tuning purposes. The availability
of OLIS is therefore a crucial element for the delivery of RIB to experiments.
OLIS Uptime
100
90
80
70
60
50
40
30
20
OLIS Uptime
10
0
2001
2002
2003
2004
2005
2006
2007
Figure 4 Off Line Ion Source uptime; average is greater than 97%
Drift Tube Linac and Radio Frequency Quadrupole Uptime 2001 -2007
Percentage of Scheduled Operational Hours per Year
100
90
80
70
60
50
40
30
20
RFQ
DTL
10
0
2001
2002
2003
2004
2005
Figure 5 The RFQ and DTL accelerators
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2006
2007
The uptime for the ISAC DTL and RFQ accelerators is demonstrated in Figure 5 and
averages well above 95%. The Phase I SCRF linac has an availability of nearly 100%
since its completion in 2006.
The large overhead for ISAC target changes and the on line development of targets
significantly impacts the available time to RIB experiments. This has been identified as a
bottle neck in the previous (2005-2010) Five-year Plan request in the form of an
additional proton beam line (BL4N) and target stations. Figure 6 represents the lost
hours of RIB to experiments as a percent of scheduled hours. This is overhead associated
with target preparation and set up for proton beam acceptance.
Percent of Scheduled RIB Hours Lost for Target Preparation
30
25
20
15
10
5
0
1999
2000
2001
2002
2003
2004
2005
2006
2007
Figure 6 Percentage of scheduled RIB hours lost (downtime for all systems is non-coincidental)
4. Present Effort Required to Operate Delivery Systems
The Accelerator Division maintains repairs and operates (MRO) TRIUMF’s accelerators
on a `round the clock’1 basis with an operations group and technical support staff totaling
approximately 130 Full Time Equivalents (FTE)2. The technical support staff comes
from the Accelerator, Administration and Engineering Divisions (but excludes
administrative overhead) and includes the refurbishing and development effort associated
with maintaining the high percentage of beam availability. The majority of the total FTE
effort comes from the Accelerator Division and relates directly to laboratory operations
and development with the balance coming from services and infrastructure support
groups.
Accelerator physicists/researches account for approximately 10-15% of the 130 FTE, 2025% are in the engineering category and the balance being technical staff. Existing
staffing levels need to be augmented to improve RIB delivery, enhance maintenance
activities and to meet ever increasing regulatory requirements. As an example, a
significant FTE effort is necessary to meet the obligatory Canadian Nuclear Safety
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2
TR13 operates ~ 12 hours per day, five days per week
Based on salary allocation data March 31, 2007
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Commission mandated Quality Assurance program. The 2005-2010 Five-Year Plan
proposal identified the need for increased staffing levels. In particular, the need for 22
additional FTE for increased ISAC operations was identified. Unfortunately the 20052010 budget allocation did not support the proposed staffing increase. Through
succession planning, reorganization and ongoing needs analysis some manpower
reallocation has taken place. However, this effort is not sustainable and impacts other
TRIUMF activities. Additional resources are required irrespective of any new initiatives
undertaken at TRIUMF.
5. Future Effort Required to Operate Delivery Systems
The new high intensity electron machine will deliver beams to one of the new target
stations. Radioactive beam production will expand from one production target at any
given time to three targets in simultaneous production. The ISAC beams capability will
increase from one RIB and one stable beam simultaneously to up to three RIB beams
simultaneously with two of the RIBs accelerated. These new initiatives will require
additional resources to provide a comparable level of service as is now provided to
existing facilities. The actual operation of the facility would most efficiently be done by
an amalgamation of the operations groups in a single expanded control room. Ideally the
combined control area would be centrally located to provide quick access to equipment.
This concept has significant advantages; the operations group works closely with controls
and safety personnel, beam physicists and coordinators who all need to be in close
proximity. It would also allow the overall on-shift operations effort to remain at near
present levels. The technology of the cyclotron controls make a remote operation
upgrade more difficult and time consuming than an EPICS control interface move.
However, the anticipated costs and effort associated with such a move are not expected to
appreciably increase the overall cost of amalgamation in a combined control area. As an
alternative, the existing TRIUMF 500 MeV control room and adjacent area could be
expanded to support a combined centralized operation. Support groups however may not
have sufficient room to be in close proximity to operations. In either case a Human
Factors Engineering study is required by the regulatory agency (CNSC). The expansion
of operations area would require an estimated 300-500k of renovations and installations.
The electron linac will be installed with an EPICS control interface as will all of the
ISAC upgrades. Even though the beam delivery network is significantly expanded (one
new cyclotron beamline, one new driver and beamline, two new targets and RIB beams)
the number of operators will not have to expand in direct proportion since the accelerator
readiness and tuning for technical equipment across the site will not be done
simultaneously. It is envisaged that one shift supervisor and four operators per shift
would be sufficient to run the facility with an expanded beam delivery team of beam
physicists to offer expert tuning and daily interaction. Additional beam physicists at a
Post-doc or junior researcher level would be required to handle the expanded beam
delivery network. Presently TRIUMF employs 24 operators. Full staffing of five
operators per shift would require an additional operator. Additional staffing will be
needed to augment coordinating, training and overhead relief tasks for the new initiatives.
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The technical teams for maintaining and monitoring the facility will need to be expanded
particularly in the ISAC target stations, hot cell operations and target production but also
in controls, vacuum, cryogenics, RF, safety and beam lines. Three simultaneous beams
capability means three times the number of targets and target hall activities. It is intended
that the new target stations be designed to facilitate faster target turn around and reduce
the possibility of loose contamination. In general the technology that is being added in
the Five-Year Plan is not unique to TRIUMF and new hires need not be required at the
senior level but could be sourced to fill junior and intermediate ranks. New
infrastructures such as the helium recovery and liquefier plant, electrical and mechanical
services are anticipated to all require additional support.
6. Summary
The heart of TRIUMF, the 500 MeV cyclotron, has operated very reliably (uptime
averaging ~90%) for many years and is expected to continue at level as beam intensities
increase. The ISAC accelerators average better than 97% availability and highlight the
need to reduce ISAC target overhead. Although the present Five-Year Plan did not
include sufficient resources to address this and other issues, TRIUMF, through
succession planning, reorganization and ongoing needs analysis, has made some resource
reallocation to mitigate the operational impact. Additional resources are required tackle
this and other impacted areas irrespective of any new initiatives undertaken at TRIUMF.
TRIUMF has been successful in its past endeavours. TRIUMF’s highly skilled staff is
motivated and committed to excellence and anticipates a stimulating and challenging
future.
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