# Comments on a Review of Specifications for Primary Beamline Instrumentation

**July 26, 2001**

## Beamline Designer's Perspective on Instrumentation

## Presenter: P. Lucas

1.  ([Reviewer: J. Crisp]{.underline}) I would like to see as much
    detail as possible for the following systems:

    a.  auto-tune

    b.  beam extraction permit

    c.  beam loss budget monitor

I understand these systems will be discussed Aug 17. Are there engineers
assigned to these systems? Is there sufficient engineering support to
insure success with these systems?

2.  [(Reviewer: P. Czarapata]{.underline}) The specifications for the
    instrumentation are clearly tied to one of two types of need,
    regulatory or operational. Without showing an overall system that
    was being used to address these two areas, it was impossible to
    determine the specifications.

    a.  Derive a \"system\" view of the instrumentation that addresses
        which of the two needs the system is intended to serve. Describe
        it\'s \"primary\" mission and it\'s \"secondary\" mission. For
        example: If the torroid is used to satisfy regulatory or safety
        requirements it must have an accuracy of x.x% and be
        auto-calibrating. If it is also used for monitoring the primary
        beam to the experiment it needs a second output with an accuracy
        of x.x and long term stability of xx ppm.

    b.  Develop the real specifications for the instrumentation
        including environmental.

    c.  Postpone the implementation review until the specifications are
        written and understood by the engineers and consider
        re-reviewing them with this group.

3.  ([Reviewer: R. Ford]{.underline}) A non-trivial effort will be
    required to design a BLM system which is foolproof to use for
    groundwater protection. Not only must the long BLM system have a
    heartbeat, but you must able to show that it is working all along
    the length of the monitor.

4.  ([Reviewer: R. Ford]{.underline}) The long BLMs or Total Loss
    Monitors (TLMs) as we use to call them should be used for the entire
    length of the beamline on a separate system from the standard BLMs
    in case some part of the control system goes down. One percent of
    the beam continuously lost would not be noticed by a toroid or eberm
    but could create a no-man\'s land in the beamline. This is also a
    concern for Miniboone.

5.  ([Reviewer: R. Ford]{.underline}) All of the concerns about the
    autotune program will likely be resolved well in advance of NuMI
    operation. Autotune is a non-trivial project that will be of great
    concern to Miniboone.

6.  ([Reviewer: R. Ford]{.underline}) I hope that someone actually
    calculated the wire heating and shock on the multiwires where the
    beam is small.

7.  ([Reviewer: R. Ford]{.underline}) How many pulses does it take to
    burn a hole in something? Even though NuMI claims they don\'t need
    an eberm system, they will need something similar. Lucky for them,
    Miniboone\'s design should be almost plug and play for NuMI.

8.  ([Reviewer: R. Ford]{.underline}) NuMI should investigate whether
    they need an Rf monitor like a resistive wall monitor. It may be
    used for gating events in the near detector and/or as a beam present
    detector to tell the toroids when to be active.

9.  ([Reviewer: R. Ford]{.underline}) A better understanding of the Rf
    gymnastics required for bunch rotation between NuMI and PBar
    production. Considering the dispersion requirements, this must be
    monitored and automated.

10. ([Reviewer: M. Gerardi]{.underline}) Potential loss points and
    allowable limits should be specifically identified, and the
    mechanism for monitoring and reacting defined. There is an approval
    process for systems considered interlocked which takes some time to
    approve especially for unproven schemes.

11. ([Reviewer: M. Gerardi]{.underline}) The BBM aspects of the system
    should be dedicated to avoid timing problems and inadequate data
    taking. Protons delivered whether they appear lost or not will need
    to be clearly and accurately logged.

12. ([Reviewer: M. Gerardi]{.underline}) How close to the groundwater
    limit is the requested yearly intensity ?

13. ([Reviewer: M. Gerardi]{.underline}) Do we have a commissioning plan
    ?

14. ([Reviewer: M. Gerardi]{.underline}) BPM\'s have never been proven
    to work efficiently with an auto-tune system.

15. ([Reviewer: M. Gerardi]{.underline}) The radiological an
    environmental issues associated with the monitoring systems for
    accessability and maitenance do not appear to have been addressed.

16. ([Reviewer: M. Gerardi]{.underline}) Has any of the proposed
    instrumentaion been designed ?

17. ([Reviewer: M. Gerardi]{.underline}) How do we get gas to the loss
    monitors, or maintain the distribution system ?

18. ([Reviewer: W. Kissel]{.underline}) My main concern continues to be
    \"auto tune\". It has been recommended by earlier reviews to
    establish a prototype for auto tune in a similar operational area.
    (pbar production - rapid duty cycle, hi intensity, MI era operation)
    Of examples stated, KTev auto tune worked well but all other auto
    tune efforts in the BD have had serious operational problems. Given
    the demands of NuMI operations and in the event that power supply
    stability is less than desired, auto tune must function reliably and
    accurately. We really need existence proof in the hi duty cycle, hi
    intensity, low loss environment.

19. ([Reviewer: P. Martin]{.underline}) The toroids were requested to
    have an absolute accuracy of 3%. The issues of definition need to be
    clarified. If the statement is that the absolute accuracy must be
    better than 3% of full scale, that is probably not adequate for low
    intensity tune-up. But 3% accuracy at all intensities is not
    achievable. This issue needs to be better understood. Additionally,
    since the toroids will be used for the beam budget monitor and for
    numerous other purposes, details of buffering of the outputs needs
    to be specified, so that one user cannot affect the others.
    Datalogging of the signals needs to be specified...how and where
    will this be done? Reliability should be specified.

20. ([Reviewer: P. Martin]{.underline}) The multiwires that will be used
    for beam profile measurements cannot remain in the beam 100% of the
    time due to the unacceptable beam losses that occur from the wires
    themselves. Since the frames are much thicker, even a few pulses of
    beam could be disastrous, and therefore the provisions need to be
    implemented to prevent beam from being extracted (the *beam
    extraction permit system*) if the multiwires are in an intermediate
    state, and to inhibit NuMI beam at the ion source (the *beam permit
    system*) prior to software commands to insert or retract the wires.
    The permit can only be restored once every multiwires reads fully in
    or out of the beam and will require operator intervention.

21. ([Reviewer: P. Martin]{.underline}) The BPMs are known to be
    sensitive to beam striking the plates. False signals could lead to
    auto-tune diverging. While it was stated that the low levels of loss
    that can be tolerated shouldn't be a problem, I would recommend this
    be studied further as part of the P1 line studies.

22. ([Reviewer: C. Moore]{.underline}) It was good to see redundant long
    loss monitors in the carrier region. I would like to see at least
    one long loss monitor just upstream of the carrier pipe region, in
    fact if the monitors have not been ordered one could consider just
    making these two longer.

23. ([Reviewer: C. Moore]{.underline}) I asked the question if
    Multiwires could be inserted at high intensities. The answer was yes
    based on MARS studies. I assume that runs were made for the
    insertion of each wire and the pattern of radiation was examined to
    see if the losses in the most crucial regions were too high. A
    question which I did not ask is " Were the wires studied
    individually or was there one run with all the wires inserted". The
    effect of multiple scattering with all the wires in might lead to
    more losses than would be apparent from studying the wires one by
    one.

24. ([Reviewer: C. Moore]{.underline}) Slip stacking is not on the
    agenda for NuMI at least in the beginning. If it were the question
    of momentum spread would have to be carefully studied.

25. ([Reviewer: C. Moore]{.underline}) The requirement on toroid
    accuracy for the beam-based input was not mentioned on the slide but
    5% was deemed sufficient.

26. ([Reviewer: C. Moore]{.underline}) Peter will have SY120 and
    MiniBooNE to practice on in terms of debugging Autotune.

27. ([Reviewer: R. Pasquinelli]{.underline}) The sensitivity to momentum
    spread due to vertical dispersion was presented. Due to the multi
    use of Main Injector beam in the future, it will be very important
    to understand the longitudinal dynamics planned for the Main
    Injector. Pbar production requires high momentum spread, NuMI
    requires low. Currently there is difficulty with Pbar beam lines;
    hence, bunch rotation is manipulated frequently. Operational
    conflicts could result. Consultation with Beams Division RF and
    longitudinal dynamics experts is suggested.

28. ([Reviewer: R. Pasquinelli]{.underline}) The specifications must
    include all dynamic range requirements. Beam loss tolerances of
    10^-4^ to 10^-6^ were presented. The locations of such tolerances
    must be part of the specification. What will be expected of all
    diagnostics over the dynamic range of commissioning? It is unlikely
    the experiment will be commissioned with full beam current. At what
    level of accuracy will the instrumentation be expected to perform at
    low beam current levels?

29. ([Reviewer: R. Pasquinelli]{.underline}) While \"auto tune\"
    features of the NuMI beam line are being planned, the amount of
    effort to build a real system is beyond that of one or two
    individuals currently assigned to the task. If auto tune is indeed
    necessary, a re-evaluation of system requirements, dynamics, and
    available resources is required. This is a real time beam feedback
    system with many elements over considerable distances, not a trivial
    task.

30. ([Reviewer: R. Pasquinelli]{.underline}) An understanding of
    reliability of instrumentation channels should be investigated. How
    many loss monitor, BPM, or profile channels can be lost and still
    provide adequate operational performance?

31. ([Reviewer: B. Webber]{.underline}) Unless the present embryonic
    state of instrumentation requirements and specifications
    determination and definition is consistent with the project
    schedule, this effort needs immediate attention from additional
    resources!

32. ([Reviewer: B. Webber]{.underline}) My perception is that the
    success of whole general operational scheme as described in the
    review will depend critically on the detailed interfaces and
    interactions among the various systems including beam
    instrumentation. The review was devoid of substance in this
    important area; specifically details of beam instrumentation outputs
    and interfaces have not and need to be defined.

33. ([Reviewer: B. Webber]{.underline}) Quantitative analysis of the
    requirements and failure analyses need to be completed and
    documented (what is really required to guarantee safe regular NUMI
    operation and can/how will we operate with system X broken?). Top
    down systems designs and interfaces must be defined. Only after this
    structure is in place can the feed-downs into individual
    instrumentation systems, including required reliability, need for
    automatic on-line remote calibration, required output signals, etc.,
    be understood.

34. ([Reviewer: B. Webber]{.underline}) It was mentioned at the review
    that there are plans to implement autotune features in the P1 line
    as "proof of principle" of those features identified as "integral to
    \[NUMI\] beamline operation." Apparently, these plans were
    identified over 16 months ago at a March 2000 review. There was
    little indication at this review of progress in that direction other
    than a statement that Bob Ducar is "building a box." I would urge
    this demonstration enterprise be given the highest priority below
    Run II operation and MiniBooNE preparations (isn't that where NUMI
    is in the priority of the Beams Division?). Only by attempting
    application of these ideas within the framework of an operational
    system and the present control system will the real problems be
    recognized and faced. And when it works, Run II will benefit!! If
    it's too much effort to do now and NUMI really requires this
    functionality, then the NUMI schedule will suffer later.

## Beam Instrumentation Specifications

## Presenter: S. Childress

1.  ([Reviewer: R. Ford]{.underline}) A plot showing beam size, with
    dispersion versus aperture size would be useful for determining
    locations of instrumentation and other things.

2.  ([Reviewer: P. Martin]{.underline}) Since the BLMs are critical for
    protecting the groundwater, some means of calibration and
    verification needs to be developed. One solution might be a
    combination of electrical pulsers for the ones in the carrier
    tunnel, together with radioactive sources on similar but short BLMs,
    supplied by gas that has flowed through the active ones, placed in
    an area shielded from beam losses and from the groundwater.

3.  ([Reviewer: C. Moore]{.underline}) The instrumentation will have to
    work over a dynamic range of one hundred. This will require
    attention

4.  ([Reviewer: C. Moore]{.underline}) The question of the accuracy of
    the toroids is an issue since page 25 of the TDR states that the
    toroids will be used to inhibit beam. It was previously mentioned
    that a 5% relative difference would be used to inhibit beam. Jim
    Crisp said that in fact he could calibrate the toroids to less than
    1%.

5.  ([Reviewer: C. Moore]{.underline}) The high voltage on the loss
    monitors will be monitored but this is not sufficient to ensure that
    the monitor is working.

6.  ([Reviewer: C. Moore]{.underline}) There is not redundant loss
    monitor coverage over the full longitudinal range. There is
    redundant loss monitor coverage in the carrier pipe. MARS studies
    have been used to judiciously place the short loss monitors at
    possible loss locations. Although MARS is a very useful program it
    depends on the ability of the user to model every possible loss
    scenario. I would recommend that there be long loss monitor coverage
    of the entire range of the beamline, this would provide some
    redundancy for the short loss monitors. Of course one could just
    double up the short loss monitors but then one is relying on the
    MARS studies having covered every possible loss scenario.

7.  ([Reviewer: C. Moore]{.underline}) The development of a heartbeat
    for the loss monitors is imperative.

8.  ([Reviewer: C. Moore]{.underline}) Solving the stale data problem
    for Multiwires and BPMs is an urgent problem for every project that
    intends to use Autotune and in fact it can even fool experienced
    tuners.

9.  ([Reviewer: R. Pasquinelli]{.underline}) It must be made very clear
    exactly what hardware is incorporated in system diagnostics that is
    not critical to personnel or environmental safety. The loss monitor
    system presented clearly has safety considerations, but the level of
    detail presented did not make that distinction.

10. ([Reviewer: R. Pasquinelli]{.underline}) The TESLA test facility is
    utilizing a fiber optic based beam loss monitoring system that can
    not only localize the dose rate but also provides an integrated loss
    indicator. The contact at DESY is Kay Wittenburg
    (<kay.wittenburg@desy.de>). This technique could be valuable to the
    NuMI project

11. ([Reviewer: R. Pasquinelli]{.underline}) The environment in the NuMI
    tunnels looks to be inhospitable from radiation, moisture, and
    temperature. These details must be included in the specifications.
    It may also be necessary to utilize hermetic enclosures and
    connectors, which will add considerable expense to the installation.

12. ([Reviewer: R. Pasquinelli]{.underline}) The need for auto
    calibration of torroids is not well understood. If it were
    available, it would be useful. NuMI needs to establish if it is
    indeed necessary to the success of the experiment.

13. ([Reviewer: R. Pasquinelli]{.underline}) At the next review, the
    number of channels, locations, and distances for data collection for
    all primary beam diagnostics should be listed along with the
    specifications.

14. ([Reviewer: R. Pasquinelli]{.underline}) How much of the proposed
    instrumentation is already designed (or has past proven
    performance), needs further R&D, or has no resources allocated. This
    information is critical to get priority for resources from the
    Laboratory management.

15. ([Reviewer: S. Pruss]{.underline}) I disagree with the philosophy of
    accepting whatever the instrumentation group can supply "off the
    shelf". Especially for Beam Loss Monitors, I think Scarecrows from
    the Radiation Protection Group would be much more appropriate.

16. ([Reviewer: S. Pruss]{.underline}) I just read the PAC2001 paper
    "Modeling of the Primary Proton Beamline of the Fermilab Numi
    Project" by S. Childress et.al. This states that "The nominal phase
    space considered is 15π mm-mrad 95% emittance *with a 40π cut on
    beam tails*." Italics are mine for emphasis. The Main Injector
    Department does not support the concept that the beam extracted from
    the Main Injector will not have tails extending out beyond 40π. I
    suggest the beamline should have movable scattering targets in the
    upstream end of the beamline shortly after extraction to monitor the
    beam halo. These should also be located at a large dispersion point
    since the ∂p/p limit of 10^-4^ is also not assured.

17. ([Reviewer: B. Webber]{.underline}) The review panel noted several
    important instrumentation equipment specification/design criteria as
    absent from the presentations, e.g. environmental conditions,
    reliability, and tie-ins to safety systems. These must be included
    within a complete specification since they may drive significant
    departures from existing designs.

18. ([Reviewer: B. Webber]{.underline}) It was recommended that
    instrumentation specifications be classified according to the
    priority of the function served: personnel safety, regulatory
    performance monitoring and documentation, equipment protection,
    integral real-time operational support (e.g. part of autotune), and
    non-critical beam monitoring and diagnostics.

19. ([Reviewer: B. Webber]{.underline}) The "Technical Design Handbook",
    Revised July 2001, states that there are conditions, including
    "extraction to antiproton has failed to occur or has indicated
    problems" and "internal measures of MI beam quality are off
    nominal," that can prevent beam from being extracted from Main
    Injector. No details were provided and no comprehensive answer was
    offered to the question as to what impact this application has for
    existing MI/Pbar diagnostics. It is not obvious that the data and
    interface provided by the existing MI and antiproton instrumentation
    systems satisfy the requirements for application to the NUMI
    problem.

20. ([Reviewer: J. Zagel]{.underline}) I\'m concerned about which
    instrument is used for what purpose. We have typically isolated
    machine/personnel protection from operational instruments. It looks
    like this will not be possible.