Target%20Status%20Report

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Target Status Report

• Lara Howlett
• University of Sheffield

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Contents

• A look at the specs
• Reminder of Prototype plans
• Meetings with ISIS engineers
• Testbeam plans
• Status of electronics, readout and radiation
  studies
• Plans / Timescale

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Updated Specs

• Frequency 1-3 Hz. Higher may be possible but we
  may be limited by heating
• Target will dip into the beam by 5-10mm
• Only the intersection of the beam in the last 1ms
  is useful
• We wish to intersect as little beam that is not
  useful as possible

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Updated Specs
2.05ms
4.4mm
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Updated Specs
2.75ms
7.4mm
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Updated specs
3.35ms
9.8mm
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Overview of Prototype

• The prototype is currently being built and is
  expected to be ready by the end of the month
• The design consists of a a magnetic shuttle to
  which the target rod is attached
• This sits inside a series of coils which are
  driven in 3 phase

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Prototype
8 cm
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Target Mechanism
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Meetings with ISIS

• Several very useful meetings have taken place
  with engineers from ISIS
• These have been very useful for beginning to look
  at
• Safety issues
• Vacuum issues
• How the target mechanism will be mounted
• A first set of engineering drawings have also
  been produced by Stephanie Yang

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Outcomes

• The diaphragm springs will most likely be
  replaced by ceramic bearings
• The target will be mounted on a replacement for
  the current A frame to reduce vibrations
  transmitted to the beam pipe by the target
• The possibility of replacing the inductive
  measurement system with an optical system is
  under investigation
• The possibility of mounting the target using
  nested bellows with a gate valve which would
  allow the target to be completely removed from
  the beam in case of failure is being investigated

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Schematic
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Status of Electronics

• The electronics consists of two separate
  integrated circuits
• Control logic
• Current controller

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Control Logic
Position Decoder/Switching Sequencer
Optical Isolators
Hex-Bridge Electronic 3 Phase Motor Switch (6
MOSFETS)
Hall Switches (Position Sensors)
ACTUATOR
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Current Controller
Active Current Control
Position Decoder/Switching Sequencer
PWM _at_ 19.5 kHz
User Set Current (8-Bit Resolution)
Current Transducer
Hex-Bridge Electronic 3 Phase Motor Switch (6
MOSFETS)
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Future Plans

• To test this prototype circuitry with the
  actuator in order to ascertain its performance
• Development of a quadrature position sensing
  system (to replace the hall switches) This will
  allow greater control of the switching due to
  improved position information.
• To develop an interface that will allow the
  electronics to be controlled via a PC

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Radiation Studies

• Simulations of radiation levels have continued
• These now include the geometry of the target
  mechanism
• Radiation levels in the magnet are extremely high

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Radiation studies
Units Grays/year/ Unit Density
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Status of Readout

• Problems with the readout board were experienced
  which caused jumps in the counts which were read
  out
• After long correspondance with the company who
  provided the board, and returning the board for
  tests twice the problem has been resolved
• The readout system will therefore be ready to be
  used with the new prototype when it arrives
• Sheffield will have a summer student who will be
  working on this in the coming months

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Test Beam Plans

• There are plans to have the prototype ready for a
  test operation by December
• This would involve intersecting a few ISIS beam
  pulses when the machine starts up in January
• Measurements from the scintillators of the
  Glasgow group will hopefully allow us to gain a
  better understanding of how far into the beam we
  need to go and how the beam profile changes with
  distance

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Backup plans

• In parallel with the work described two backup
  plans are being investigated in the background
• The use of a lever to move the actuator away from
  the target
• The use of a cam to provide the motion

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Lever

• Despite the hope that a lever would provide a
  mechanical advantage discussions with an engineer
  indicate that because of the low mass of the
  shuttle this is not possible
• However the use of a lever would give the
  advantage of moving the electronics and magnets
  away from the radiation if this is necessary
• The other advantage of this arrangement is that
  the target mechanism is isolated from the ISIS
  vacuum eliminating any possible problems of
  contamination

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Cam

• The idea of a cam has also been investigated in
  the background so that in the instance that the
  em design does not produce the accelerations
  required a backup plan is in place. This would be
  used in conjunction with a lever

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Plans

• Upcoming milestones
• Prototype should be assembled and ready for tests
  to begin mid July
• Prototype should be sufficiently tested to put in
  the beam by Christmas
• Data from beam tests should be used as input for
  final design

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Conclusions

• Work towards the prototype is progressing and we
  expect to start tests in the coming weeks
• Several successful meetings with ISIS engineers
  have taken place and these have been extremely
  useful in progressing with the design
• Exactly how far we need to go into the beam has
  significant implications for the design, so we
  should pin this number down as much as we can